Minimal Diversity of Drug-Resistant Mycobacterium tuberculosis Strains,South Africa

Multidrug- (MDR) and extensively drug-resistant tuberculosis (XDR TB) are commonly associated with Beijing strains. However, in KwaZulu-Natal, South Africa, which has among the highest incidence and mortality for MDR and XDR TB, data suggest that non-Beijing strains are driving the epidemic. We conducted a retrospective study to characterize the strain prevalence among drug-susceptible, MDR, and XDR TB cases and determine associations between strain type and survival. Among 297 isolates from 2005–2006, 49 spoligotype patterns were found. Predominant strains were Beijing (ST1) among drug-susceptible isolates (27%), S/Quebec (ST34) in MDR TB (34%) and LAM4/KZN (ST60) in XDR TB (89%). More than 90% of patients were HIV co-infected. MDR TB and XDR TB were independently associated with mortality, but TB strain type was not. We conclude that, although Beijing strain was common among drug-susceptible TB, other strains predominated among MDR TB and XDR TB cases. Drug-resistance was a stronger predictor of survival than strain type. Key words: Mycobacterium tuberculosis, drug resistance, transmission, genotype, South Africa, HIV, bacteria, tuberculosis, tuberculosis and other mycobacteria, antimicrobial resistanceDrug-resistant tuberculosis (TB) has emerged as a substantial threat to advances in global TB control over the past several decades (1). Worldwide, an estimated 630,000 cases of multidrug-resistant (MDR) TB occurred in 2011, and extensively drug-resistant (XDR) TB has now been reported in 84 countries (2). MDR TB and XDR TB are each associated with very high mortality rates (3), and their transmission—both in community and health care settings—remains an ongoing challenge in resource-limited settings and in countries with high rates of HIV co-infection.In South Africa, the incidence of MDR TB has increased 5-fold since 2002 (2,4). MDR TB treatment is now estimated to consume more than half of the budget allocated for TB control in South Africa (5). The emergence of XDR TB, and its associated high mortality rates, have further underscored the need for clarifying the factors driving the drug-resistant TB epidemic to better focus control efforts (3,6,7).Drug-resistant TB is generally considered a human-made phenomenon that occurs when inadequate TB treatment creates selection pressure for the emergence of drug-resistant Mycobacterium tuberculosis subpopulations (acquired resistance) (1). Researchers initially believed that the mutations causing drug resistance would exert a “fitness cost,” rendering those strains too weak to be transmitted (8,9). Nonetheless, transmission of drug-resistant TB strains has now been well-documented (10–13), and laboratory studies have shown that clinical strains may have minimal fitness costs or even none (14). Emerging data suggest that most MDR TB and XDR TB cases in South Africa and worldwide are likely caused by primary transmission of drug-resistant strains (2,15–19).Although the M. tuberculosis W/Beijing strain family has been described among cases of drug-susceptible, MDR TB, and XDR TB in South Africa, numerous other strain types have also been identified (20,21). Little is known about the transmissibility and virulence of M. tuberculosis strains aside from the W/Beijing strain family (22,23). In the Eastern Cape and Western Cape Provinces of South Africa, strains from the W/Beijing family have most often been associated with transmission of drug-resistant TB (24–27). At our study site in KwaZulu-Natal Province, however, the LAM4/KZN strain type has predominated among MDR TB and XDR TB cases and has been linked to nosocomial transmission and high mortality rates (3,16,17,28,29). This strain is a member of the Euro-American strain family and was first described in this region in 1994, evolving into an increasingly resistant phenotype over time (29).The reasons for why the LAM4/KZN strain is prominent in KwaZulu-Natal Province, rather than the Beijing strain, which is seen globally and in other parts of South Africa, is unclear. Moreover, it is unknown whether the higher mortality among patients with MDR TB and XDR TB in KwaZulu-Natal can be explained, in part, by a difference in genotypic prevalence and associated differences in strain virulence (3,6,7,28). In this study, we sought to characterize the genotypic diversity of M. tuberculosis strains among isolates causing drug-susceptible TB, MDR TB, and XDR TB in KwaZulu-Natal Province, South Africa. We also examined the relationship between M. tuberculosis strain, drug resistance, and patient survival.     

Mass antibiotic treatment for group A streptococcus outbreaks in two long-term care facilities

Outbreaks of invasive infections caused by group A β-hemolytic streptococcus (GAS) may occur in long-term care settings and are associated with a high case-fatality rate in debilitated adults. Targeted antibiotic treatment only to residents and staff known to be at specific risk of GAS may be an ineffective outbreak control measure. We describe two institutional outbreaks in which mass antibiotic treatment was used as a control measure. In the first instance, mass treatment was used after targeted antibiotic treatment was not successful. In the second instance, mass treatment was used to control a rapidly evolving outbreak with a high case-fatality rate. Although no further clinical cases were seen after the introduction of mass antibiotic treatment, persistence of the outbreak strain was documented in one institution >1 year after cases had ceased. Strain persistence was associated with the presence of a chronically colonized resident and poor infection control practices.Group A β-hemolytic streptococcus (GAS) has a longstanding association with pharyngitis, skin and soft tissue infection, and pneumonia (1–3). In the past decade, reports of GAS-associated necrotizing fasciitis and streptococcal toxic shock syndrome (TSS) have increased (2,4). Increasingly, outbreaks of invasive GAS are recognized in long-term care facilities (5–10). In the Canadian province of Ontario, 4% of invasive GAS cases occur in long-term care facilities, and of these cases, one third are outbreak associated (5). In long-term care settings, a high case-fatality rate has been observed (40% to 60%) (5,11,12).Guidelines for control of GAS outbreaks in nursing homes were developed by the Ontario Ministry of Health in 1995 (13). These guidelines emphasize the identification and elimination of colonization through providing antibiotics to those known to be carriers of the bacterium. Although such an approach should minimize antibiotic exposure, carrying it out in practice could be difficult, as cultures may be falsely negative (14), and persons could become colonized or transmit colonization to others in the interval between culturing and treatment. Antibiotic treatment of all residents and staff would not be subject to such limitations. We present two outbreaks of invasive GAS infection in long-term care facilities in Hamilton, Ontario, Canada. Each was caused by transmission of a single well-characterized outbreak strain, and in both cases, mass antibiotic treatment was used to control the outbreak.     

Burkholderia pseudomallei Isolates in 2 Pet Iguanas,California, USA

Burkholderia pseudomallei, the causative agent of melioidosis, was isolated from abscesses of 2 pet green iguanas in California, USA. The international trade in iguanas may contribute to importation of this pathogen into countries where it is not endemic and put persons exposed to these animals at risk for infection.Key words: Burkholderia pseudomallei, iguana, zoonoses, abscess, melioidosis, bacteriaBurkholderia pseudomallei, a gram-negative bacterium, is the causative agent of melioidosis. Melioidosis is endemic in countries in Southeast Asia and in northern Australia, and has been sporadically reported from Central and South America (1). In the United States, most case-patients have traveled to disease-endemic areas (2).B. pseudomallei infection occurs through direct cutaneous inoculation with soil or water containing B. pseudomallei and through ingestion or inhalation of aerosolized bacteria. In humans, the incubation period is typically 1–21 days, but some patients demonstrate clinical signs years after exposure (1). Acute melioidosis can manifest as a severe pneumonia and septicemia, with death rates >40% in countries where access to medical care is limited. In chronic melioidosis, abscesses occur in various organs, including the lungs, liver, spleen, and cutaneous sites (1,3). In animals, abscesses and acute illness are common (4).B. pseudomallei is classified by US federal agencies as a tier 1 select agent. Tier 1 agents are believed to pose the greatest threat for deliberate misuse and potential harm to public health. Multiple regulations restrict access to these agents and reduce the risk of their release from secure settings (5). Infection is generally diagnosed by culture. Commercially available bacterial identification systems may provide initial identification; however, B. pseudomallei may be misidentified by some systems (6). Other identification tests are available, including PCR and antigen detection; these are not commonly used outside disease-endemic regions (3,7,8).     

West Nile virus encephalitis and myocarditis in wolf and dog

In the third season (2002) of the West Nile virus epidemic in the United States, two canids (wolf and dog) were diagnosed with West Nile virus encephalitis and myocarditis with similarities to known affected species (humans, horses, and birds). The West Nile virus infections were confirmed by immunohistochemistry and polymerase chain reaction.Since its 1999 introduction in New York, West Nile virus (WNV) has spread to >40 states, causing seasonal mosquito-borne disease in humans, horses, and birds (1–7). We recently identified two Illinois canids (a captive wolf and a domestic dog) with severe disease associated with WNV infection.Outside the Western Hemisphere, WNV has been endemic for decades (4,8–11). Canids have not been thought to be important in the epidemiology of this virus. However, a dog with neurologic disease that died in Africa in 1977 is now thought to have been infected with WNV (9,12). In a recent study in which four dogs were experimentally infected, no clinical disease was observed, and a low viremia developed in one dog (11). Natural infections occur in dogs, as indicated by serum antibodies; seropositivity in surveys was 37% in the 1980s in South Africa, 24% in the 1990s in India, and 5% in 1999 in New York City (10,11,13). In addition, a few individuals of some mammalian species have been listed as infected (not diseased): 14 bats, four rodents, three rabbits, two cats, two raccoons, and a skunk (6).     

Multidrug-Resistant Salmonella enterica Serotype Typhi,Gulf of Guinea Region,Africa

We identified 3 lineages among multidrug-resistant (MDR) Salmonella enterica serotype Typhi isolates in the Gulf of Guinea region in Africa during the 2000s. However, the MDR H58 haplotype, which predominates in southern Asia and Kenya, was not identified. MDR quinolone-susceptible isolates contained a 190-kb incHI1 pST2 plasmid or a 50-kb incN pST3 plasmid.Typhoid fever, which is caused by Salmonella enterica serotype Typhi, is endemic to the developing world; there were an estimated 26.7 million cases in 2010 (1). The incidence of typhoid fever in sub-Saharan Africa was an estimated 725 cases/100,000 persons in 2010, despite a lack of incidence studies conducted in West and central Africa (1). Antimicrobial susceptibility data are also scarce for this part of Africa. This issue is problematic because treatment with appropriate antimicrobial drugs is essential for recovery in the context of the global emergence of multidrug resistance.In the Indian subcontinent and Southeast Asia, the multidrug-resistant (MDR) Salmonella Typhi H58 clone, which was named after its haplotype (a combination of defined chromosomal single-nucleotide polymorphisms [SNPs]) (2,3), has spread rapidly and become endemic and predominant. During the 1990s, this clone acquired a large conjugative incHI1 pST6 plasmid encoding resistance to ampicillin, chloramphenicol, and co-trimoxazole (4,5); also in the 1990s, this MDR clone became resistant to quinolones and showed decreased susceptibility to ciprofloxacin because of point mutations in the chromosomal gyrA gene (2). The H58 clone has also spread to eastern Africa, where it has been the most prevalent haplotype (87%) in Kenya since the early 2000s (6).During 1997–2011, high incidence of MDR Salmonella Typhi was reported in some countries near the Gulf of Guinea in Africa, including Nigeria (7), Ghana (8,9), Togo (10), and the Democratic Republic of the Congo (11). During 1999–2003, a British surveillance system reported a prevalence of 19% (49/421) for MDR Salmonella Typhi isolates among imported cases of typhoid fever acquired in Africa, particularly in Ghana (12). However, nothing is known about the genotypes of these isolates, including whether they belong to the spreading MDR H58 clone.We report data for the occurrence, genotypes, and characterization of the resistance mechanisms of MDR Salmonella Typhi isolates. These isolates were obtained from the French National Reference Center for Salmonella (FNRC-Salm), Institut Pasteur (Paris, France), and Centre Pasteur du Cameroun (Yaoundé, Cameroon).     

Whole-Genome Characterization of Epidemic Neisseria meningitidis Serogroup C and Resurgence of Serogroup W,Niger, 2015

In 2015, Niger reported the largest epidemic of Neisseria meningitidis serogroup C (NmC) meningitis in sub-Saharan Africa. The NmC epidemic coincided with serogroup W (NmW) cases during the epidemic season, resulting in a total of 9,367 meningococcal cases through June 2015. To clarify the phylogenetic association, genetic evolution, and antibiotic determinants of the meningococcal strains in Niger, we sequenced the genomes of 102 isolates from this epidemic, comprising 81 NmC and 21 NmW isolates. The genomes of 82 isolates were completed, and all 102 were included in the analysis. All NmC isolates had sequence type 10217, which caused the outbreaks in Nigeria during 2013–2014 and for which a clonal complex has not yet been defined. The NmC isolates from Niger were substantially different from other NmC isolates collected globally. All NmW isolates belonged to clonal complex 11 and were closely related to the isolates causing recent outbreaks in Africa.Key words: Meningococcal meningitis, Neisseria meningitidis serogroup C, whole-genome sequencing, Niger, meningitis belt, bacteriaNeisseria meningitidis commonly causes meningitis in the African meningitis belt, where periodic meningococcal epidemics have contributed to the highest reported incidence of meningococcal meningitis in the world (1). Most meningococcal disease historically has been caused by N. meningitidis serogroup A (NmA); however, NmA disease dramatically decreased after the preventative MenAfriVac vaccination campaign was initiated in 2010 (2). Serogroup W (NmW) has been the major cause of meningococcal disease in the region since then (2).N. meningitidis serogroup C (NmC) disease has rarely been reported in the meningitis belt; it has not been detected in many molecular studies of invasive isolates (3,4) and is rarely found in carriage studies (5,6). The last large NmC epidemic in Africa occurred in Burkina Faso (then Upper Volta) in 1979 (7). During 2013 and 2014, NmC outbreaks were reported in Nigeria (8). The Nigerian outbreaks were caused by a novel NmC strain with a previously undescribed sequence type, 10217 (ST-10217), which does not belong to a defined clonal complex. In 2015, an epidemic of 9,367 meningococcal meningitis cases occurred in Niger, with NmC disease comprising most laboratory-confirmed cases (9).NmW disease has been reported in the meningitis belt since the 1980s (10,11), and NmW from clonal complex 11 (CC11) has been a major concern in the region since 2001 (12). The first large epidemic of disease caused by CC11 NmW occurred during 2002 in Burkina Faso (13). Subsequently, NmW disease outbreaks were reported in Niger during 2010 and 2011, both involving CC11 (14). These outbreaks were followed by another large epidemic caused by CC11 NmW in Burkina Faso during 2012 (15). Whole-genome sequencing (WGS) analysis of diverse NmW isolates from around the world has demonstrated that a clone within CC11, commonly associated with NmC, became globally dispersed after it switched to serogroup W (16,17). WGS analyses also provided sufficient resolution to assign isolates from the meningitis belt to a long-standing regional population and to a clone that became globally dispersed after an outbreak during the 2000 Hajj pilgrimage (16,17; A. Retchless, unpub. data).In addition to distinguishing among closely related strains, WGS provides information about allelic variation in genes that may affect antibiotic susceptibility and the coverage of protein-based vaccines. Two vaccines designed for serogroup B meningococcus have been approved for use in the United States and Europe: Trumenba and Bexsero. Trumenba targets the factor H–binding protein (FHbp), and includes components belonging to FHbp subfamilies A and B (18). Bexsero includes 4 different components: an FHbp of variant 1 (subfamily B); a Neisseria adhesion A protein (NadA); a neisserial heparin-binding antigen (NhbA); and outer membrane vesicles from a serogroup B strain containing PorA P1.4 (19). Recognizing the diversity of these genes among strains can aid in evaluating whether these vaccines may provide protection. Likewise, whole-genome sequences can be rapidly screened for indications of antibiotic resistance when the genetic determinants are well characterized, as with genes penA, gyrA, and rpoB, which are involved in reduced susceptibility to penicillin, ciprofloxacin, and rifampin, respectively. To clarify the meningococcal population in Niger during the 2015 epidemic season, we completed genomic analysis on the 102 NmC and NmW invasive isolates collected during this period.     

Cephalosporin-resistant Escherichia coli among summer camp attendees with salmonellosis

Investigation of an acute gastroenteritis outbreak involving >100 persons at a summer camp in Girona, Spain, in June 2002 led to the detection of Salmonella and extended-spectrum cephalosporin-resistant Escherichia coli (ESCREC). Stool cultures were performed for 22 symptomatic campers, three asymptomatic food handlers, and 10 healthy household members. Of the 22 campers, 19 had Salmonella enterica, 9 had an ESCREC strain carrying an extended-spectrum β-lactamase, and 2 had a second ESCREC strain carrying a plasmidic cephamycinase. Related ESCREC were detected in two (salmonella-negative) asymptomatic food handlers and in none of the healthy household members. Fecal ESCREC and its β-lactamases and plasmids were extensively characterized. Three of the five ESCREC clones were recovered from multiple hosts. The apparent dissemination of ESCREC suggests a food or water vehicle. The observed distribution of resistance plasmids and β-lactamase genes in several clones indicates a high degree of horizontal transfer. Heightened vigilance and increased efforts must be made to discover the reservoirs and vehicles for community dissemination of ESCREC.Strains of Escherichia coli that produce enzymes capable of degrading extended- spectrum cephalosporins (ESCs), i.e., extended-spectrum β-lactamases (ESBLs), or these drugs plus cephamycins, i.e., plasmidic or hyperproduction of chromosomal cephamycinases have recently emerged as important nosocomial pathogens (1,2). Some of these strains cannot be reliably detected by clinical microbiology laboratories by using conventional susceptibility tests (3), and even when recognized, treating infections caused by these strains can be challenging because therapeutic options are limited. Infections attributable to such strains are associated with prolonged hospital stays, increased healthcare costs, and an increased number of deaths if appropriate therapy is delayed (4,5).To date, almost all reports of infection or colonization with ESBL- and plasmidic cephamycinase-producing E. coli (i.e., extended-spectrum cephalosporin-resistant E. coli [ESCREC]) have involved hospitalized patients or nursing home residents (3,6). The few reported patients with community-acquired infection have been elderly and debilitated and have had hospital contact, important coexisting conditions, or both (3,6).E. coli, including resistant strains, may be transmitted within the community through the food supply. Indeed, other gram-negative enteric pathogens, notably Salmonella enterica, are a frequent cause of foodborne disease and, increasingly, are associated with antibiotic resistance, including antibiotic resistance to ESCs (7–11). Available data regarding other resistant E. coli suggest that ESCREC could also be disseminated through the food supply (12–19).The cefoperazone-containing medium routinely used in our laboratory for the isolation of Campylobacter occasionally yields other bacteria with hyperproduction of chromosomal β-lactamases or their plasmidic derivatives, as well as strains carrying extended-spectrum β-lactamases (unpub. data). By using this media, we have isolated several resistant enterobacteriaceae strains from patients with sporadic cases of gastroenteritis (unpub. data). During an investigation of a summer camp-associated salmonellosis outbreak, we observed that stool cultures from nine campers unexpectedly yielded, on cefoperazone-containing medium, colonies resembling enterobacteriaceae, with a uniform mucoid appearance. This result suggested the possibility that the same, probably ESC-resistant, enterobacterial strain was present in all these persons, findings consistent with possible foodborne spread. Consequently, all samples were reevaluated on media containing cefotaxime (see Methods) to increase sensitivity for detection of ESC-resistant organisms. To gain more knowledge of foodborne spread as a potential mechanism of dissemination of resistance genes, we undertook an extensive molecular epidemiologic analysis of these isolates.     

West Nile virus transmission in resident birds, Dominican Republic

We report West Nile virus (WNV) activity in the Dominican Republic for the first time. Specific anti-WNV antibodies were detected in 5 (15%) of 33 resident birds sampled at one location in November 2002. One seropositive bird was <4 months old, indicating a recent infection.The initial outbreak of West Nile virus (WNV; family Flaviviridae, genus Flavivirus) in the Western Hemisphere took place in New York in 1999, with deaths observed in humans, horses, and numerous species of wild birds (1). Since then, this virus has spread rapidly across North America (2,3). Migratory birds are suspected of being responsible for the rapid spread of WNV through North America (4), and transport of WNV by Neotropical migratory birds throughout the New World has been anticipated (5).Although WNV has spread rapidly through continental areas, its ability to spread across oceanic barriers is uncertain. The many islands of the West Indies represent the wintering grounds of numerous North American migratory birds (6,7) that breed in or migrate through WNV transmission foci in the United States. The Caribbean islands tend to have high human population density, and low populations of many birds and other vertebrates are restricted to certain islands. Introduction of WNV to the West Indies would present a human and equine health concern and potentially threaten numerous endangered and endemic bird species and perhaps other wild vertebrates.Given the speculation that WNV may be disseminated by migrating birds (5,8,9), we hypothesized that the virus would be introduced to the Dominican Republic. Accordingly, we sampled apparently healthy birds there for evidence of locally acquired WNV infection.     

Escherichia coli O157 exposure in Wyoming and Seattle: serologic evidence of rural risk

We tested the hypothesis that rural populations have increased exposure to Escherichia coli O157:H7. We measured circulating antibodies against the O157 lipopolysaccharide in rural Wyoming residents and in blood donors from Casper, Wyoming, and Seattle, Washington, by enzyme immunoassay (EIA). EIA readings were compared by analysis of variance and the least squares difference multiple comparison procedure. Rural Wyoming residents had higher antibody levels to O157 LPS than did Casper donors, who, in turn, had higher levels than did Seattle donors (respective least squares means: 0.356, 0.328, and 0.310; p<0.05, Seattle vs. Casper, p<0.001, rural Wyoming vs. either city). Lower age was significantly correlated with EIA scores; gender; and, in rural Wyoming, history of bloody diarrhea, town, duration of residence, and use of nontreated water at home were not significantly correlated. These data suggest that rural populations are more exposed to E. coli O157:H7 than urban populations.Escherichia coli O157:H7 is an important human pathogen. This organism can affect humans in a variety of ways, ranging from asymptomatic carriage (1) to diarrhea, bloody diarrhea (the most common manifestation of illness in culture-proven cases), and the postdiarrheal thrombotic microangiopathy, hemolytic uremic syndrome (HUS) (2). Infections with E. coli O157:H7 in the Pacific Northwest of the United States have been endemic (3) and epidemic (4). Vehicles transmitting this pathogen include unpasteurized milk and juice (5,6), undercooked beef (7), drinking water (8), and contact with infected persons (9).Data from the Centers for Disease Control and Prevention (CDC) demonstrate higher incidences of E. coli O157:H7 infections in rural counties in the United States than urban (Paul Mead, unpub. data). Worldwide, rural populations have been postulated to be at greater risk for exposure to E. coli O157:H7 by virtue of increased exposure to animals or their excreta in Scotland (10,11); dairy farm visits have been implicated as a source for infection in Finland (12) and the United States (13); and animal contacts are a risk factor for the development of HUS in Switzerland (14). Serologic studies from Canada demonstrated higher frequencies of antibodies to the O157 lipopolysaccharide (LPS) side chain among residents of rural areas compared to residents of urban areas (15), and in Wisconsin children, manure and sheep contact were recently demonstrated to be risk factors for O157 seropositivity (16). Taken together, these data suggest more intense or more frequent human exposure to E. coli O157:H7 in nonurban areas.Populations in the Pacific Northwest and Rocky Mountain states provide an opportunity to assess the frequency of exposure to E. coli O157:H7 through serologic studies. Antibodies to the O157 LPS follow natural infection with E. coli O157:H7 (17) and are believed to be quite specific (18) because they are rarely found in healthy people. Thus, circulating antibodies to the O157 LPS are potential markers of population exposure to E. coli O157:H7. We therefore attempted to assess the distribution of antibodies to this antigen in three different populations, encompassing a gradient of population density.     

Small colony variants of Staphylococcus aureus and pacemaker-related infection

We describe the first known case of a device-related bloodstream infection caused by Staphylococcus aureus small colony variants. Recurrent pacemaker-related bloodstream infection within a 7-month period illustrates the poor clinical and microbiologic response to prolonged antimicrobial therapy in a patient infected with this S. aureus subpopulation.Infections caused by Staphylococcus aureus range from mild skin infections to acute life-threatening diseases such as pneumonia, osteomyelitis, and endocarditis. However, S. aureus may also cause a chronic disease with persistent and recurrent infections. Skin and soft tissue infections, chronic osteomyelitis, and persistent infections in patients with cystic fibrosis have been associated with small colony variants, a naturally occurring subpopulation of the species S. aureus (1–6). S. aureus small colony variants are characterized as electron transport deficient bacteria because of their auxotrophism to hemin or menadione or are recognized as thymidine-dependent. These variants produce very small, mostly nonpigmented and nonhemolytic colonies. In addition, they also demonstrate various other features that are atypical for S. aureus, including reduced coagulase production, failure to use mannitol, and increased resistance to aminoglycosides and cell-wall active antibiotics (3–10). Furthermore, the ability of these variants to persist intracellularly within nonprofessional phagocytes has been described (3,5,11). Because of their fastidious growth characteristics and unusual morphologic appearance, small colony variants present a challenge both to the microbiologist and the clinician, often resulting in misidentification and misinterpretation (1,2,7,8). Prerequisite for recovering and identifying these variants is the application of extended conventional culture and identification techniques (3,5,8). We report the first case of a pacemaker-related bloodstream infection caused by S. aureus small colony variants. This case illustrates the poor clinical and microbiologic response to prolonged antimicrobial therapy in patients infected with these variants.     

Experimental Infection of Squirrel Monkeys with Nipah Virus

We infected squirrel monkeys (Saimiri sciureus) with Nipah virus to determine the monkeys’ suitability for use as primate models in preclinical testing of preventive and therapeutic treatments. Infection of squirrel monkeys through intravenous injection was followed by high death rates associated with acute neurologic and respiratory illness and viral RNA and antigen production.Key words: Nipah virus, emergent infection, primates, pathogenesis, squirrel monkey, Saimiri sciureus, ELISA, immunohistology, RT-PCR, encephalitis, viruses, zoonoses, dispatchNipah virus (NiV) is a highly pathogenic zoonotic paramyxovirus that was first identified in Malaysia and Singapore in 1999 (1). Since the initial outbreak, NiV has been associated with human illness in Bangladesh and India (2) and was classified, together with the closely related Hendra virus, in the genus Henipavirus. Reported human death rates varied from 40%–92% (3), and some outbreaks were associated with human-to-human transmission (4). Most human infections led to encephalitis with vasculitis-induced thrombosis in the brain and atypical pneumonia in certain patients (5,6). Because of the lack of efficient treatment or a vaccine for Nipah virus and the high pathogenicity of the virus in humans, the manipulation of NiV requires BioSafety Level 4 (BSL-4) conditions.Several species of fruit bats of the genus Pteropus are considered natural reservoirs of henipaviruses, although the disease does not develop in them (7). Pigs were responsible for amplifying the NiV infection in Malaysia, but their death rate was only 10%–15%. Laboratory infection of piglets caused development of neurologic signs in some animals, and NiV was detected in different tissues (8). Hamsters in laboratory studies are highly susceptible to NiV, and infection develops in multiple organs, including the brain (9). Cats infected with NiV in the laboratory reproduce the disease observed in naturally infected cats, including a severe respiratory and systemic disease, 6–13 days after infection (10). However, to our knowledge, a primate model necessary for preclinical testing of preventive and therapeutic approaches has not been described. We therefore assessed the squirrel monkey (Saimiri sciureus) as an experimental model of NiV infection.     

Distinct Zika Virus Lineage in Salvador,Bahia, Brazil

Sequencing of isolates from patients in Bahia, Brazil, where most Zika virus cases in Brazil have been reported, resulted in 11 whole and partial Zika virus genomes. Phylogenetic analyses revealed a well-supported Bahia-specific Zika virus lineage, which indicates sustained Zika virus circulation in Salvador, Bahia’s capital city, since mid-2014.Key words: Zika virus, ZIKV, flaviviruses, Bahia, Brazil, mosquito-borne infections, outbreak surveillance, metagenomic next-generation sequencing, viral genome assembly, capture probe enrichment, phylogenetic analysis, molecular clock, viruses, vector-borne infectionsZika virus is an arthropodborne RNA virus primarily transmitted by mosquitoes of the species Aedes (1). The virus has 2 genotypes: African, found only in the continent of Africa; and Asian, associated with outbreaks in Southeast Asia, several Pacific islands, and, recently, the Americas (2). In May 2015, Brazil reported its first autochthonous cases of Zika virus infection, which occurred in northeast Brazil (3,4). As of June 30, 2016, all 27 federal states in Brazil had confirmed Zika virus transmission (http://www.paho.org/hq/index.php?option=com_docman&task=doc_view&Itemid=270&gid=35262&lang=en).The rapid geographic expansion of Zika virus transmission and the virus’s association with microcephaly and congenital abnormalities (5) demand a rapid increase in molecular surveillance in areas that are most affected. Molecular surveillance is particularly relevant for regions where other mosquitoborne viruses, particularly dengue and chikungunya viruses, co-circulate with Zika virus (2); surveillance on the basis of clinical symptoms alone is highly inaccurate. Genetic characterization of circulating Zika virus strains can help determine the origin and potential spread of infection in travelers returning from Zika virus–endemic countries. Previous analyses have suggested that Zika virus was introduced in the Americas at least 1 year before the virus’s initial detection in Brazil (1). The state of Bahia, Brazil, reported most (93%) suspected Zika virus infections in Brazil during 2015 (2), including cases of Zika virus–associated fetal microcephaly (6); however, except for 1 complete genome, no genetic information from the region has been available (2,7). We report molecular epidemiologic findings resulting from 11 new complete and partial Zika virus genomes recovered from serum samples from patients at the Hospital Aliança in the city of Salvador in Bahia, Brazil.     

Anthelmintic baiting of foxes against urban contamination with Echinococcus multilocularis

In recent years, increases in the urban fox population have been observed in many countries of the Northern Hemisphere. As a result, Echinococcus multilocularis has entered the urban environment. Because of a possible increased risk for alveolar echinococcosis, intervention strategies need to be evaluated. In Zürich, Switzerland, 50 praziquantel-containing baits per km² were distributed monthly in six 1-km² bait areas and one 6-km² bait area from April 2000 through October 2001. The proportion of E. multilocularis coproantigen–positive fox fecal samples collected remained unchanged in six control areas but decreased significantly in the 1-km² bait areas (from 38.6% to 5.5%) and in the 6-km² bait area (from 66.7% to 1.8%). E. multilocularis prevalence in the intermediate host Arvicola terrestris also decreased significantly in baited areas. This controlled baiting study shows that a pronounced reduction of E. multilocularis egg contamination is feasible in urban areas where the organism is highly endemic.The zoonotic tapeworm Echinococcus multilocularis is typically perpetuated in a wild life cycle, which includes foxes (genera Vulpes and Alopex) as definitive hosts and various rodent species as intermediate hosts (1). In addition, eggs are accidentally ingested by humans; the metacestodes enter mainly the liver and cause alveolar echinococcosis, a severe, sometimes fatal disease if left untreated (2,3).Few studies have been performed on the epidemiology of alveolar echinococcosis. Risk factors for alveolar echinococcosis may include occupational and behavioral activities. However, hunters, trappers, and persons working with fur were not at increased risk for alveolar echinococcosis in South Dakota (4). Data from Europe have indicated that farming activities increase the risk for infection (5,6). Contamination of the rural environment with E. multilocularis connected with farming activities was indirectly demonstrated by high prevalences of alveolar echinococcosis in sows kept indoors but fed with grass (7). Areas with high water vole (Arvicola terrestris) densities yielded a 10-fold higher risk for human alveolar echinococcosis compared with areas with low densities of this important intermediate host (8). In an area where the organism is highly endemic, up to 39% of A. terrestris and up to 7% of dogs with free access to rodents were infected with E. multilocularis (9), and persons who have kept dogs around dwellings were at higher risk for alveolar echinococcosis on St. Lawrence Island, Alaska (10).Red foxes (Vulpes vulpes) are likely to be the most important final host in many regions (11). In the past 2 decades, foxes have started to colonize in cities around the world (12–14), and evidence of the parasite cycle in urban areas is increasing (13,15,16). In Zürich, Switzerland, one study found that 47% of the urban fox population was infected with E. multilocularis (17).The high number of infected foxes in cities and villages, in close contact with domestic pets and humans, could increase the risk of alveolar echinococcosis (16). The disease has an incubation period of 5 to 15 years; therefore, whether the actual incidence rate of alveolar echinococcosis reflects a continuing stable and low infection risk or whether the increased infection pressure in highly populated areas will lead to a delayed increase in the incidence of alveolar echinococcosis cases in the future is unclear (3). However, ecologic changes resulted in a very high alveolar echinococcosis prevalence of 4.0% in China, which is highly endemic for the organism (18). The high prevalence of E. multilocularis in densely populated areas and the increase of foxes living in close vicinity to humans strongly suggest that evaluating possible intervention strategies is prudent.Few field studies focus on anthelmintic treatment of definitive hosts. Rausch et al. (10) demonstrated in a village that was hyperendemic for the organism (St. Lawrence Island, Alaska) that continual treatment of dogs with praziquantel reduces infection pressure of E. multilocularis, resulting in lower prevalence in locally trapped voles. In extended rural areas of Germany and Japan, praziquantel baits lowered the prevalence of E. multilocularis in foxes (19–21). These results cannot be transferred to the condition of agglomerations and urban areas, where until now no attempt has been made to evaluate an intervention strategy for foxes.The urban cycle of E. multilocularis was studied intensively in Zürich, Switzerland (16,17,22). Analyses of fox stomachs indicated that A. terrestris was the most frequently consumed intermediate host (23), and E. multilocularis is highly prevalent (mean 9.1%, maximum 20.9%) in this vole species, which lives predominantly along the city border (22). Accordingly, the prevalence of E. multilocularis in foxes was significantly higher in the urban periphery than in more central areas (17), and the infection risk for alveolar echinococcosis might therefore be concentrated mainly in delimited areas in the urban periphery (16). Since urban inhabitants frequently use the zones of highest contamination for recreational activities and their domestic cats and dogs have access to infected voles, the urban periphery may represent a risk for alveolar echinococcosis.In this controlled experimental field study, we investigated the effect of anthelmintic baiting in defined urban areas where the organism is highly endemic and tested whether E. multilocularis egg contamination was significantly reduced. We also examined whether, as an expected consequence, its prevalence in urban intermediate hosts diminished.     

Superantigens and streptococcal toxic shock syndrome

Superantigens produced by Streptococcus pyogenes have been implicated with streptococcal toxic shock syndrome (STSS). We analyzed 19 acute-phase serum samples for mitogenic activity from patients with severe streptococcal disease. The serum samples from two patients in the acute phase of STSS showed strong proliferative activity. Streptococcal mitogenic exotoxin (SME) Z-1 and streptococcal pyrogenic exotoxin (SPE)-J were identified in one patient with peritonitis who recovered after 2 weeks in intensive care. SMEZ-16 was found in a second patient who died on the day of admission. Sequential serum samples taken on day 3 after admission from patient 1 showed clearance of mitogenic activity but absence of neutralizing anti-SMEZ antibodies. Serum samples taken on day 9 from this patient showed evidence of seroconversion with high levels of anti-SMEZ antibodies that neutralized SMEZ-1 and 12 other SMEZ-variants. These results imply that a high level of SMEZ production by group A streptococcus is a causative event in the onset and subsequent severity of STSS.Since the 1980s, a marked increase has occurred in highly invasive group A streptococcal (GAS) infections, in particular streptococcal toxic shock syndrome (STSS) associated with necrotizing fasciitis or myositis (1–4). The classical case definition for STSS is similar to staphylococcal toxic shock, caused by Staphylococcus aureus, but the outcome is more serious in STSS, with a reported death rate of 30% to 70% (2,5,6).The multiorgan involvement in STSS suggests that a toxin produced by GAS might be involved in pathogenesis. Prime candidates are the streptococcal superantigens (SAgs), a family of highly mitogenic proteins secreted individually or in certain combinations by many Streptococcus pyogenes strains (7–10), although other virulence factors, such as Streptolysin O and various cell wall antigens can also cause toxic shock (11). Superantigens simultaneously bind to major histocompatibility complex class II molecules and T-cell receptor molecules bearing a particular V-β region. This binding results in the activation of a large proportion of antigen-presenting cells and T cells, with subsequent release of high systemic levels of cytokines (12–15).Several lines of evidence support the hypothesis of SAg involvement in STSS. Toxic shock syndrome (TSS) toxin, produced by S. aureus, has been associated with most menstrual TSS cases (7). TSS toxin is a typical SAg that is functionally and structurally related to the staphylococcal and streptococcal SAgs (16). Moreover, animal models have shown that TSS toxin and other SAgs induce TSS-like symptoms in rabbits and rodents (17,18). The lack of neutralizing anti-SAg antibodies appears to be a key risk factor for the development of staphylococcal and streptococcal toxic shock (19,20).The major cytokines released from antigen-presenting cells and T cells after activation by SAgs are tumor necrosis factor alpha (TNF-α), tumor necrosis factor beta (TNF-β), interleukin (IL)-1, and IL-2 (11–14). TNF-α is the prime mediator of shock; anti–TNF-α has been shown to inhibit the progression of SAg-driven shock in mice and baboons (17,18,21).In contrast to TSS toxin and staphylococcal TSS, the association of individual streptococcal SAgs to STSS is much less understood. Several studies described the potential involvement of streptococcal pyrogenic exotoxin (SPE) A in invasive streptococcal disease (2,19,22,23), while others reported an association with SPE-C (24,25). In addition, some cases of STSS are not associated with SPE-A or SPE-C (26). Notably, these studies were performed without knowledge of other streptococcal SAgs that are now known to exist.Superantigen activity found in acute-phase serum samples from streptococcal disease patients has been reported. (In this article, the term “acute-phase serum” refers to serum taken on the day of admission). Sriskandan et al. published a study of seven patients with severe streptococcal infections: SPE-A was detected in serum samples from four patients (27). Recently, Norby-Teglund and Berdal reported a strong proliferative response in an acute-phase serum sample collected from a patient with STSS, indicating that the sample contained an unknown SAg (28). Mitogenic activity was also detected in serum samples from mice infected with a SAg-producing S. pyogenes strain (29).Since these reports, several novel streptococcal SAgs have been identified, including streptococcal mitogenic exotoxin Z (SMEZ; 30), SMEZ-2, SPE-G, SPE-H (31), SPE-J, and SPE-I (32), all possessing typical SAg features and highly mitogenic on human T cells. In addition, several variants of SMEZ showed significant antigenic variation (33). These findings suggest that, in addition to SPE-A and SPE-C, one or more of these novel toxins might be involved in STSS.All known streptococcal SAgs (with the exception of SMEZ, SPE-G, and SPE-J) are localized on mobile DNA elements (34). As a consequence, each GAS isolate usually carries the genes for SMEZ, SPE-G, and SPE-J, plus a certain combination of other sag genes. Not much is known about the control of sag gene expression, but a recent study indicates that an unknown host factor is involved in the control of SPE-C expression (35)We analyzed serum samples from 19 patients with severe streptococcal infections for mitogenic activity to identify bioactive SAgs and find a correlation between SAg activity and disease severity. In addition, we genotyped the matching streptococcal isolates from these patients for all known streptococcal sag genes and tested them for their ability to produce SAg protein in vitro.     

Potential Sexual Transmission of Zika Virus

In December 2013, during a Zika virus (ZIKV) outbreak in French Polynesia, a patient in Tahiti sought treatment for hematospermia, and ZIKV was isolated from his semen. ZIKV transmission by sexual intercourse has been previously suspected. This observation supports the possibility that ZIKV could be transmitted sexually.Zika virus (ZIKV) is a mosquitoborne arbovirus in the family Flaviviridae, genus Flavivirus. It was first isolated in 1947 from a rhesus monkey in the Zika forest of Uganda (1). Sporadic human cases were reported from the 1960s in Asia and Africa. The first reported large outbreak occurred in 2007 on Yap Island, Federated States of Micronesia (2). The largest known ZIKV outbreak reported started in October 2013 in French Polynesia, South Pacific (3), a territory of France comprising 67 inhabited islands; an estimated 28,000 persons (11% of the population) sought medical care for the illness (4). The most common symptoms of Zika fever are rash, fever, arthralgia, and conjunctivitis. Most of the patients had mild disease, but severe neurologic complications have been described in other patients in French Polynesia (5).     

Hantavirus Infections among Overnight Visitors to Yosemite National Park,California, USA, 2012

In summer 2012, an outbreak of hantavirus infections occurred among overnight visitors to Yosemite National Park in California, USA. An investigation encompassing clinical, epidemiologic, laboratory, and environmental factors identified 10 cases among residents of 3 states. Eight case-patients experienced hantavirus pulmonary syndrome, of whom 5 required intensive care with ventilatory support and 3 died. Staying overnight in a signature tent cabin (9 case-patients) was significantly associated with becoming infected with hantavirus (p<0.001). Rodent nests and tunnels were observed in the foam insulation of the cabin walls. Rodent trapping in the implicated area resulted in high trap success rate (51%), and antibodies reactive to Sin Nombre virus were detected in 10 (14%) of 73 captured deer mice. All signature tent cabins were closed and subsequently dismantled. Continuous public awareness and rodent control and exclusion are key measures in minimizing the risk for hantavirus infection in areas inhabited by deer mice.Key words: hantavirus, hantavirus pulmonary syndrome, Sin Nombre virus, Peromyscus spp., respiratory infections, virusesHantavirus pulmonary syndrome (HPS) is an acute viral disease, characterized by a nonspecific febrile illness followed by severe noncardiogenic pulmonary edema and cardiogenic shock. It is also referred to as hantavirus cardiopulmonary syndrome. Approximately 36% of reported HPS cases in the United States are fatal (1). HPS was first recognized in 1993 when an outbreak of unexplained respiratory deaths occurred among otherwise healthy adults in the southwestern United States (2–5). A previously unknown hantavirus, Sin Nombre virus (SNV), was identified as the etiologic agent (6,7). Deer mice (Peromyscus maniculatus) are the reservoir for SNV (8), which infected mice shed in their urine, saliva, and feces. Humans are exposed chiefly by inhaling aerosolized excreta. Activities associated with increased risk for HPS include occupying or cleaning rodent-infested buildings, sweeping or disturbing rodent excreta or nests, sleeping on the ground, and handling mice without gloves (9–11). Person-to-person transmission of SNV has not been documented (12).During 1993–2011, a total of 587 cases of HPS were confirmed in the United States, primarily in western states (Centers for Disease Control and Prevention [CDC]/Viral Special Pathogens Branch, unpub. data). Although household clusters of HPS have been reported (13,14), most HPS cases occur as single, sporadic disease incidents. In August 2012, the California Department of Public Health (CDPH) confirmed HPS in 2 California residents, both of whom had visited Yosemite National Park (Yosemite) in June 2012 and had lodged in so-called signature tent cabins (which differ from regular tent cabins by having an interior wall and roof consisting of drywall with a layer of foam insulation between the drywall and exterior canvas) in the Curry Village area of Yosemite Valley. Because of the common travel history of these otherwise nonepidemiologically unrelated patients, CDPH, in collaboration with CDC, the National Park Service (NPS) Office of Public Health, and others, initiated an investigation of a possible HPS outbreak associated with Yosemite. This report summarizes the clinical, epidemiologic, laboratory, and environmental findings of the investigation.     

Chlamydia trachomatis infections in female soldiers, Israel

We examined the prevalence of Chlamydia trachomatis infection in Israeli female soldiers. The prevalence was 3.2% among soldiers seeking medical care; rural residence was identified as a significant risk factor. Nevertheless, given the study design, recommending broad-scale screening of Israeli female soldiers may be premature.²Recent studies from the United States and Europe report that the prevalence of Chlamydia trachomatis ranges from 5% to 20% in sexually active persons (1,2). Among women, the consequences of the disease include pelvic inflammatory disease, ectopic pregnancy, and infertility, sequelae often accompanied by a substantial economic impact (3). Most importantly, for up to 80% of infected women, infection is asymptomatic, resulting in failure to seek timely medical care and the exacerbation of such sequelae (4). Consequently, screening programs have been recommended to reduce infection, transmission, and disease consequences (4,5). However, before such programs are universally advocated, since the cost-effectiveness of such control programs is at least partially contingent upon disease prevalence (5), more data are required to assess the extent to which such prevalence rates may indeed be generalizable to other countries and populations.Epidemiologic research indicates that prevalence rates of C. trachomatis vary, with a number of risk factors accounting for a substantial portion of this variance (4). For example, in the landmark study by Gaydos et al., significant risk factors for the prevalence of this infection among American female military recruits included age (women <25 years of age were at higher risk), vaginal intercourse, lack of condom use, and multiple sexual partners (4). Given that sexual practices such as condom use and multiple sex partners are likely to vary from country to country, we designed a study to assess the prevalence of C. trachomatis in a population of Israeli women, namely female soldiers, who, according to previous research, had a heightened risk of having the disease because of their age and sexual activity (4–6).     

Mayaro virus in wild mammals, French Guiana

A serologic survey for Mayaro virus (Alphavirus, Togaviridae) in 28 wild nonflying forest mammal species in French Guiana showed a prevalence ranging from 0% to 52% and increasing with age. Species active during the day and those who spent time in trees were significantly more infected, results consistent with transmission implicating diurnal mosquitoes and continuous infectious pressure.The Mayaro virus is a zoonotic Alphavirus (family Togaviridae) responsible for epidemics of febrile exanthematous illness in Latin America and Amazonia (1). Although the death rate is low, Mayaro fever is a major arboviral infection relevant to public health in rural populations, with an increasing incidence of human cases in the Amazonian basin following ecosystem disturbances (2). The activity of the Mayaro virus can be described as a constantly moving wave, transmitted among susceptible vertebrates by sylvatic Culicidae mosquitoes (3). Haemagogus mosquitoes are the main vectors; they are diurnal canopy dwellers common in high pristine rainforests (4). Several vertebrate hosts, mainly primates, rodents, and birds, are considered to be reservoirs, although their exact role in maintaining the virus is insufficiently understood (2). Previous serologic surveys have shown high prevalence rates in primates, but the virus has been isolated only from lizards and one marmoset (5,6); experimental inoculation of marmosets resulted in a short period of viremia, although the titer was nevertheless probably high enough to infect vectors (4). Human disease outbreaks could occur when birds or vectors introduce the virus into rural areas with high densities of both Haemagogus and potential reservoirs.This emerging disease has recently been reported in French Guiana, a French administrative unit on the northern coast of South America (6). To investigate the diversity of the reservoir species, a serologic survey for Mayaro virus was conducted on 28 nonflying mammalian rainforest species, in a total of 579 animals; no previous surveys in wild vertebrate species has included so many samples. Investigations on antibody responses in potential hosts are important first steps for understanding viral dynamics (7). Since the infectious process plays a major role in wildlife ecology (8), we used Mayaro infection as a case study to investigate the correlation between ecologic and biologic patterns of potential hosts and their susceptibility to infection.     

Molecular Model of Prion Transmission to Humans

To assess interspecies barriers to transmission of transmissible spongiform encephalopathies, we investigated the ability of disease-associated prion proteins (PrP^d) to initiate conversion of the human normal cellular form of prion protein of the 3 major PRNP polymorphic variants in vitro. Protein misfolding cyclic amplification showed that conformation of PrP^d partly determines host susceptibility.Key words: Transmissible spongiform encephalopathy, disease transmission, model system, prions, amino acid sequence, conformation, molecular characteristics, protein misfolding cyclic amplification, dispatchThe agents responsible for the transmissible spongiform encephalopathies (TSEs) are called prions. Although their precise biochemical composition is a matter of debate, they are known to occur in a series of strains, each with a characteristic disease phenotype and host range (1). A central event in neuropathogenesis of TSEs is conversion of the normal cellular form of the prion protein (PrP^C) to the pathognomonic disease-associated isoform (PrP^d) (2). In the absence of a known nucleic acid genome, it has been proposed that the strain-like properties of different TSE agents are encoded by distinct self-propagating conformational variants (conformers) of PrP^d (3). The best developed method available for typing these PrP^d isoforms uses limited proteolysis and classification of the protease-resistant prion protein (PrP^res) in terms of the sizes of the nonglycosylated fragment(s) produced and the ratio of the 3 possible glycoforms (3). If distinct conformers and glycotypes of PrP^d are responsible for diversity of prion strains, then they would be expected to be able to impose these molecular characteristics onto PrP^C of the same amino acid sequence (when transmitted or replicating within a species) and onto PrP^C of a different primary sequence (when transmitted between species). In support of this theory, the agent responsible for the TSE of cattle, called bovine spongiform encephalopathy (BSE), the accepted cause of variant Creutzfeldt-Jakob disease (vCJD) in humans (4), has been shown to be transmissible to at least 7 species (1), resulting in propagation of PrP^d that retains the characteristic molecular signature of the original BSE prion strain (5–7).Current thinking favors a seeded polymerization model for the conversion of PrP^C into PrP^d, which has led to the development of several cell-free in vitro conversion model systems (8). One such system is protein misfolding cyclic amplification (PMCA) (9), in which small amounts of PrP^d introduced (seeded) into substrate containing excess PrP^C and other essential conversion cofactors can be amplified to readily detectable levels by sequential cycles of sonication and incubation. We have previously reported that the molecular characteristics, electrophoretic mobility, and glycoform ratio of the PrP^res associated with the vCJD PrP^d conformer were faithfully reproduced by PMCA (10). However, the efficiency of amplification achieved depended on the substrate’s prion protein gene codon 129 (PRNP-129) genotype. The most efficient amplification was achieved in a methionine homozygous (PRNP-129MM) substrate; the least efficient, in a valine homozygous (PRNP-129VV) substrate. To estimate the molecular component of transmission barriers for particular TSE agents between species, we used PMCA reactions to amplify PrP^d associated with vCJD (10), bovine BSE (11), ovine scrapie (12), and experimental ovine BSE (13) and substrates prepared from humanized transgenic mouse brain tissue expressing each of the 3 main PRNP polymorphic variants found in Caucasian human populations (PRNP-129MM, MV, and VV) (14).     

Cat or dog ownership and seroprevalence of ehrlichiosis, Q fever, and cat-scratch disease

Concerns have been raised about the role of domestic cats or dogs in the acquisition of zoonoses, in particular in pregnant women or immune-suppressed persons. We report that cat or dog ownership is not associated with an increased seroprevalence of antibodies to Anaplasma phagozytophilum, Coxiella burnetii, and Bartonella henselae in symptom-free persons in Styria, Austria.Keeping pet cats and dogs is very popular in Austria. However, these animals can serve as reservoirs for the agents of important bacterial infectious diseases and as a potential source of infection for humans, even though the infectious animals may be asymptomatic. Infections are potentially transmitted from domestic animals to humans by scratches, bites, or close contact. Examples for such infections include human granulocytic ehrlichiosis (Anaplasma phagocytophilum), cat-scratch disease (CSD, Bartonella henselae), and Q fever (Coxiella burnetii).Cats are known to be the most important source of infections for B. henselae (aeroprevalence in Austrian cats is 33%) (1). However, dogs may also transmit B. henselae (2). Animals are contagious through their blood, which may contaminate saliva in cases of gum bleeding. Fleas from infected animals may contain the infectious agent, and bites from these fleas can transmit CSD. Typically, CSD is a benign and self-limiting disease in humans, occurring with lymphadenopathy, low-grade fever, primary cutaneous inoculation lesion, and weight loss, lasting 6–12 weeks. Rarely observed atypical signs and symptoms include erythema nodosum, figurate erythemas, thrombocytopenic purpura, Perinaud’s oculoglandular syndrome, encephalopathy, hepatic granulomas, osteomyelitis, pulmonary disease, and optic neuritis (3). These severe manifestations occur in immunocompetent patients, whereas bacillary angiomatosis or peliosis hepatitis are more likely to develop in immunosuppressed patients.C. burnetii infection has been associated with a chronic fatigue–like syndrome (4). Both cats and dogs are well-described reservoirs for C. burnetii (5). In humans, C. burnetii infection usually is asymptomatic (60%) or manifests as a mild disease with fever, headache, myalgias, and spontaneous recovery (5). However, this infection may lead to serious complications and even death in patients with acute disease, especially those with meningoencephalitis and myocarditis and, more frequently, in chronically infected patients with endocarditis. Q fever in pregnancy has been associated with abortion, premature birth, and low weight in newborns (6,7).Within the past several decades, the number of Ehrlichia and Anaplasma spp. recognized to infect cats, dogs, and humans has expanded substantially (8). The agent of human granulocytic ehrlichiosis (HGE) has recently been classified as A. phagozytophilum (9). The disease has influenzalike symptoms with variable degrees of anemia, thrombocytopenia, leukopenia, and elevated liver enzymes. Dogs are thought to be sentinels for assessing risk for HGE in humans (10). Cases of HGE in the United States are increasing in incidence (11). Reports of acute cases in Europe have been rare, although serosurveys of the prevalence of antibodies to A. phagocytophilum have been conducted. A survey in Slovenia showed that 15.4% of the examined population had detectable antibodies to the pathogen and several cases of HGE had been confirmed (12). No similar serosurvey has been conducted in Austria, although Ixodes ricinus, thought to be the principal vector in Europe, is present in Austria (13). We report that the rate of seropositivity of A. phagocytophilum (immunoglobulin [Ig] G antibodies 25/376 [7%], IgM antibodies 6/376 [2%]), B. henselae (88/376 [23%]), and C. burnetii (23/376 [6%]) in Styria, Austria, is not affected by cat or dog ownership.