Rickettsial infections and fever, Vientiane, Laos

Rickettsial diseases have not been described previously from Laos, but in a prospective study, acute rickettsial infection was identified as the cause of fever in 115 (27%) of 427 adults with negative blood cultures admitted to Mahosot Hospital in Vientiane, Laos. The organisms identified by serologic analysis were Orientia tsutsugamushi (14.8%), Rickettsia typhi (9.6%), and spotted fever group rickettsia (2.6% [8 R. helvetica, 1 R. felis, 1 R. conorii subsp. indica, and 1 Rickettsia "AT1"]). Patients with murine typhus had a lower frequency of peripheral lymphadenopathy than those with scrub typhus (3% vs. 46%, p<0.001). Rickettsioses are an underrecognized cause of undifferentiated febrile illnesses among adults in Laos. This finding has implications for the local empiric treatment of fever.     

Flea-borne rickettsioses: ecologic considerations.

Ecologic and economic factors, as well as changes in human behavior, have resulted in the emergence of new and the reemergence of existing but forgotten infectious diseases during the past 20 years. Flea-borne disease organisms (e.g., Yersinia pestis, Rickettsia typhi, R. felis, and Bartonella henselae) are widely distributed throughout the world in endemic-disease foci, where components of the enzootic cycle are present. However, flea-borne diseases could reemerge in epidemic form because of changes in vector-host ecology due to environmental and human behavior modification. The changing ecology of murine typhus in southern California and Texas over the past 30 years is a good example of urban and suburban expansion affecting infectious disease outbreaks. In these areas, the classic rat-flea-rat cycle of R. typhi has been replaced by a peridomestic animal cycle involving, e.g., free-ranging cats, dogs, and opossums and their fleas. In addition to the vector-host components of the murine typhus cycle, we have uncovered a second typhuslike rickettsia, R. felis. This agent was identified from the blood of a hospitalized febrile patient and from opossums and their fleas. We reviewed the ecology of R. typhi and R. felis and present recent data relevant to the vector biology, immunology, and molecular characterization and phylogeny of flea-borne rickettsioses.     

Spotted fever group and typhus group rickettsioses in humans, South Korea

The presence of the nucleic acid of the spotted fever group (SPG) and typhus group (TG) rickettsiae was investigated in 200 serum specimens seropositive for SFG rickettsiae by multiplex-nested polymerase chain reaction with primers derived from the rickettsial outer membrane protein B gene. The DNA of SFG, TG, or both rickettsiae was amplified in the 24 serum specimens, and sequence analysis showed Rickettsia conorii, R. japonica, and R. felis in the specimens. R. conorii and R. typhi were found in 7 serum specimens, which indicated the possibility of dual infection in these patients. These findings suggest that several kinds of rickettsial diseases, including boutonneuse fever, rickettsialpox, R. felis infection, and Japanese spotted fever, as well as scrub typhus and murine typhus, are occurring in Korea.     

Rickettsia felis as emergent global threat for humans

Rickettsia felis is an emergent pathogen belonging to transitional group rickettsiae. First described in 1990, R. felis infections have been reported to occur worldwide in fleas, mammals, and humans. Because clinical signs of the illness are similar to those of murine typhus and other febrile illnesses such as dengue, the infection in humans is likely underestimated. R. felis has been found throughout the world in several types of ectoparasites; cat fleas appear to be the most common vectors. R. felis infection should be considered an emergent threat to human health.     

Murine Typhus in Austin,Texas, USA, 2008

In August 2008, Texas authorities and the Centers for Disease Control and Prevention investigated reports of increased numbers of febrile rash illnesses in Austin to confirm the causative agent as Rickettsia typhi, to assess the outbreak magnitude and illness severity, and to identify potential animal reservoirs and peridomestic factors that may have contributed to disease emergence. Thirty-three human cases of confirmed murine typhus were identified. Illness onset was reported from March to October. No patients died, but 23 (70%) were hospitalized. The case-patients clustered geographically in central Austin; 12 (36%) resided in a single ZIP code area. Specimens from wildlife and domestic animals near case-patient homes were assessed; 18% of cats, 44% of dogs, and 71% of opossums had antibodies reactive to R. typhi. No evidence of R. typhi was detected in the whole blood, tissue, or arthropod specimens tested. These findings suggest that an R. typhi cycle involving opossums and domestic animals may be present in Austin.     

Rickettsia felis in Xenopsylla cheopis, Java, Indonesia

Rickettsia typhi and R. felis, etiologic agents of murine typhus and fleaborne spotted fever, respectively, were detected in Oriental rat fleas (Xenopsylla cheopis) collected from rodents and shrews in Java, Indonesia. We describe the first evidence of R. felis in Indonesia and naturally occurring R. felis in Oriental rat fleas.     

Prevalence of antibodies to Rickettsia conorii Coxiella burnetii and Rickettsia typhi in Salamanca province (Spain). Serosurvey in the human population

The Salamanca Province of Spain is an endemic zone for Mediterranean spotted fever. In this area, only one case of Q fever has been reported and typhus group rickettsial diseases have never been diagnosed. To obtain a panoramic view of the presence of antibodies to the most ubiquitous rickettsial agents, 400 sera specimens from a statistically representative sample of the human population of Salamanca City and its surrounding province were subjected to indirect microimmunofluorescent test for antibodies against Rickettsia conorii, Coxiella burnetii, phase II, and Rickettsia typhi antigens. Titers 1:40 to R. conorii were found in 73.5% of the sera. Positivity was more common in subjects who reported closer contact with the natural environment and/or with domestic animals. Seropositivity to C. burnetii, phase II, was detected in 50.2% of sera. These positive cases were related to rural environmental factors and to prevoius contact with animals. The frequency of antibodies increased with age showing a progressive exposure to the rickettsial antigen. The prevalence of antibodies to R. conorii and C. burnetii in the human population of Salamanca Province is higher than that reported from any other geographic zone. The study of antibodies to R. typhi showed that 12.5% of the sera had titers 1:40. According to our results, seropositivity to this rickettsial antigen cannot be related to any particular group of population nor interpreted totally as cross reactivity with R. conorii. Our data show a wide distribution of R. conorii and C. burnetii antigens in Salamanca Province, and also indicate the presence of R. typhi antigens in this area.     

Emerging rickettsioses of the Thai-Myanmar border

To investigate the presence of rickettsioses in rural residents of the central Thai-Myanmar border, we tested the blood of 46 patients with fever. Four patients had murine typhus, three patients had scrub typhus, and eight patients had spotted fever group rickettsioses, including the first case of Rickettsia felis infection reported in Asia.     

Real-time multiplex PCR assay for detection and differentiation of rickettsiae and orientiae

The high incidence of rickettsial diseases in Southeast Asia necessitates rapid and accurate diagnostic tools for a broad range of rickettsial agents, including Orientia tsutsugamushi (scrub typhus) and Rickettsia typhi (murine typhus), but also spotted fever group infections, which are increasingly reported. We present an SYBR-Green-based, real-time multiplex PCR assay for rapid identification and differentiation of scrub typhus group, typhus group and spotted fever group rickettsiae using 47kDa, gltA and ompB gene targets. Detection limits for amplification of these genes in reference strains ranged from 24 copies/microl, 5 copies/microl and 1 copy/microl in multiplex and 2 copies/microl, 1 copy/microl and 1 copy/microl in single template format, respectively. Differentiation by melt-curve analysis led to distinct melt temperatures for each group-specific amplicon. The assay was subjected to 54 samples, of which all cell-culture and 75% of characterised clinical buffy coat samples were correctly identified. Real-time PCR has the advantage of reliably detecting and differentiating rickettsial and orientia cell-culture isolates in a single-template assay, compared with the more time-consuming and laborious immunofluorescence assay. However, further optimisation and validation on samples taken directly from patients to assess its clinical diagnostic utility is required.     

Flinders Island spotted fever rickettsioses caused by "marmionii" strain of Rickettsia honei, Eastern Australia

Australia has 4 rickettsial diseases: murine typhus, Queensland tick typhus, Flinders Island spotted fever, and scrub typhus. We describe 7 cases of a rickettsiosis with an acute onset and symptoms of fever (100%), headache (71%), arthralgia (43%), myalgia (43%), cough (43%), maculopapular/petechial rash (43%), nausea (29%), pharyngitis (29%), lymphadenopathy (29%), and eschar (29%). Cases were most prevalent in autumn and from eastern Australia, including Queensland, Tasmania, and South Australia. One patient had a history of tick bite (Haemaphysalis novaeguineae). An isolate shared 99.2%, 99.8%, 99.8%, 99.9%, and 100% homology with the 17 kDa, ompA, gltA, 16S rRNA, and Sca4 genes, respectively, of Rickettsia honei. This Australian rickettsiosis has similar symptoms to Flinders Island spotted fever, and the strain is genetically related to R. honei. It has been designated the "marmionii" strain of R. honei, in honor of Australian physician and scientist Barrie Marmion.     

云南省玉溪市红塔区鼠型斑疹伤寒病原及血清流行病学调查

目的明确玉溪市红塔区是否为鼠型斑疹伤寒疫源地。方法采用微量室温补体结合法，对红塔区人群和鼠类进行鼠型斑疹伤寒（莫氏）立克次体血清抗体检测，用鼠、鼠体外寄生节肢动物标本接种豚鼠进行病原体分离，并调查鼠密度和鼠蚤指数。结果调查的7镇14个调查点人群血清抗体均检出阳性，总阳性率28．92％（96／332），几何平均滴度（GMT）为10．83，其中发热患者和健康人群抗体阳性率分别为31．86％（72／226）和22．64％（24／106）；男女阳性率分别为26．71％（43／161）、30．99％（53／171），性别间差异无统计学意义（P〉0，05）；年龄组阳性率分别为0-6岁29．63％（8／27）、7-18岁18．06％（13／72）、19-39岁39．62％（42／106）、40-59岁27．50％（22／80）、60岁以上23．40％（11／47），各年龄组差异有统计学意义（P〈0．05）；10个调查点捕获的鼠类均检出抗体，阳性率为44．95％（89／198），GMT为30．30；从11组鼠类标本中分离到5株莫氏立克次体，从6组蚤类标本中分离到3株莫氏立克次体，病原体分离率为44．44％（8／18），其中鼠类为45．45％（5／11）、蚤类为50．00％（3／6）；1组螨类标本接种豚鼠未引起豚鼠发病；确诊1例鼠型斑疹伤寒病例；褐家鼠和黄胸鼠占捕鼠总数的99．49％（197／198）、印鼠客蚤占捡蚤总数的74．26％（303／408），鼠蚤指数为2．06，鼠密度为11．13％。结论红塔区人群和鼠类中存在鼠型斑疹伤寒，且处在较高感染水平，可认定该区为鼠型斑疹伤寒疫源地。     

Murine typhus in children, South Texas

Children from South Texas were evaluated for immunoglobulin G to Rickettsia typhi, the causative agent of murine typhus. Of 513 children, 8.6% of those 1-5 years of age, 13.3% of those 6-11 years of age, and 13.8% of those 12-17 years of age had positive results.     

Spotted fever and murine typhus in the Negev desert region of Israel, 1981

During 1981, 52 cases of rickettsiosis caused by the spotted fever group of rickettsiae were reported in a population of 250 000 living in the Negev desert region of Israel. Retrospectively, at least 5 of these cases were serologically shown to have been caused by Rickettsia typhi, the agent of murine typhus. Most cases of rickettsial disease occurred in the summer months and one half of all cases occurred in children aged 9 years or less. While the specificity of a physician''s diagnosis of the rickettsial diseases appears to be high (i.e., few cases of other diseases are misdiagnosed as either spotted fever or murine typhus), the sensitivity of the physician''s diagnosis may be lower (i.e., many cases of these diseases presenting as fevers of unknown origin are not diagnosed as rickettsial disease). These findings may also be important for other countries of the region.     

Rickettsia felis in Fleas, Southern Ethiopia, 2010

TO THE EDITOR: Fleas (order Siphonaptera) are obligate hematophagous insects. They are laterally flattened, holometabolous, and wingless ectoparasites. More than 2,500 species of flea, belonging to 16 families and 238 genera, have been described. A minority of these genera live in close association with humans (synanthropic), including fleas of these species: Pulex irritans, Ctenocephalides felis, Ctenocephalides canis, Xenopsylla cheopis, Nosopsyllus fasciatus, Echidnophaga gallinacea, and Tunga penetrans (1). Many fleas are capable of transmitting the following pathogens to their hosts: bacteria (e.g., Rickettsia typhi, R. felis, Yersinia pestis, and many Bartonella spp.); viruses (e.g., myxoma virus); protozoa (e.g., Trypanosoma spp.); or helminths (e.g., Hymenolepis spp.) (2). Ctenocephalides spp. fleas are of special interest as main reservoirs and vectors of R. felis, because this agent causes an emerging disease, fleaborne rickettsiosis. The distribution and prevalence of this disease have not been well studied. Symptoms of this disease range from mild to moderate and include fever, cutaneous rash, and sometimes an inoculation eschar (3,4). R. felis can also infect at least 10 other species of arthropods, including P. irritans fleas, trombiculid and mesostygmata mites, hard and soft ticks, and booklice (5,6).     

Rickettsia felis in Ctenocephalides spp. fleas, Brazil

In June 2000, suspected cases of Brazilian spotted fever (BSF) occurred in Coronel Fabriciano Municipality, Minas Gerais State, Brazil. Pooled fleas collected near two fatal cases contained rickettsial DNA. The nucleotide sequence alignment of the 391-bp segment of the 17-kDa protein gene showed that the products were identical to each other and to the R. felis 17-kDa gene, confirming circulation of R. felis in Brazil.     

Human Rickettsia felis infection, Canary Islands, Spain

We report the first cases of human infection by Rickettsia felis in the Canary Islands. Antibodies against R. felis were found in 5 adsorbed serum samples from 44 patients with clinically suspected rickettsiosis by Western blot serology. Fleas from 1 patient's dog were positive for R. felis by polymerase chain reaction.     

茂名口岸鼠形动物及其体外寄生虫种群消长调查和相关自然疫源性疾病的预测研究

目的 调查茂名口岸鼠形动物及其体外寄生虫的种群和消长情况，对相关自然疫源性疾病的流行风险进行预测。方法 采用一般的病媒生物调查方法和血清学检测方法。结 果鼠形动物有2目2科4属7种，蚤有1种，革螨有2科5属6种，恙螨有2科5属12种，硬蜱有1科1属1种。年度动物染蚤、革螨、恙螨、硬蜱感染事分别为8．8％、39．2％、31．1％、4．0％，感染率最高的动物分别为褐家鼠、黄毛鼠、海南屋顶鼠、黄毛鼠。年度动物染蚤、革螨、蒜蠕、硬蜂感染指数分别为0．2、3．5、36．3、0．1，感染指数最高的分别为褐家鼠、黄胸鼠、黄毛鼠、海南屋顶鼠、板齿鼠。血清学检测发现斑疹伤寒阳性22份，感染率10．00％；恙虫病阳性16份，感染率7．27％；肾综合征出血热(HFRS)阳性7份，感染率3．18％；钩端螺旋体阳性1份，感染率0．45％。结论 茂名口岸地区存在恙虫病、HFRS发生和流行的风险。     

Severe Murine Typhus with Pulmonary System Involvement

We encountered a case of severe murine typhus complicated by acute respiratory distress syndrome. To determine worldwide prevalence of such cases, we reviewed the literature and found that respiratory symptoms occur in ≈30% of murine typhus patients. In disease-endemic areas, murine typhus should be considered for patients with respiratory symptoms and fever.     

Serosurvey of Rickettsia spp. in dogs and humans from an endemic area for Brazilian spotted fever in the State of São Paulo, Brazil

The present study provides a rickettsial serosurvey in 25 dogs and 35 humans in an endemic area for Brazilian spotted fever in the State of S?o Paulo, where the tick Amblyomma aureolatum is the main vector. Testing canine and human sera by indirect immunofluorescence against four Rickettsia antigens (R. rickettsii, R. parkeri, R. felis and R. bellii) showed that 16 (64%) of canine sera and 1 (2.8%) of human sera reacted to at least one of these rickettsial antigens with titers >0r= 64. Seven canine sera and the single reactive human serum showed titers to R. rickettsii at least four times those of any of the other three antigens. The antibody titers in these 7 animals and 1 human were attributed to stimulation by R. rickettsii infection. No positive canine or human serum was attributed to stimulation by R. parkeri, R. felis, or R. bellii. Our serological results showed that dogs are important sentinels for the presence of R. rickettsii in areas where the tick A. aureolatum is the main vector of Brazilian spotted fever.     

Serosurvey of wild rodents for Rickettsioses (spotted fever, murine typhus and Q fever) in Java Island, Indonesia

The prevalence of antibodies against spotted fever group rickettsia (SFGR), murine typhus and Q fever were investigated in wild rats captured in Indonesia. Sera of 327 rats were collected from Jakarta and Boyolali on Java Island. The prevalences of antibodies against SFGR and murine typhus were 128 (39.1%) and 48 (14.7%), respectively. Antibodies against Q fever were not detected in these serum samples. Antibodies against SFGR were found in all species of rats (20.8–51.9%). The antibody positive rate against murine typhus in Rattus norvegicus (38.0%) was significantly higher than that in other rat species (0–4.8%, p < 0.01). The antibody positive rates against SFGR and murine typhus in rats captured in Jakarta were significantly higher than those in rats captured in Boyolali (p < 0.01). In this survey, all species of rats had antibodies against SFGR, indicating that the 4 species of tested rats (R. norvegicus, R. rattus, R. exulans, R. tiomanicus) were infected with SFGR and that SFGR may infest the whole of Java Island. Most of the rats that were antibody-positive against murine typhus were captured in Jakarta. Therefore, R. norvegicus and R. rattus are likely to be important hosts of murine typhus in Jakarta. The antibody-positive rates against SFGR and murine typhus in rats captured in the dry season were significantly higher than those in rats captured in the rainy season. This may coincide with the active periods of ticks and fleas in Indonesia.