Nonopsonic phagocytosis of erythrocytes infected with ring-stage Plasmodium falciparum

Ring-stage parasitized erythrocytes (RPEs) were demonstrated to interact with effector cells of the innate immune system. With receptor blockade studies and CD36-null macrophages, human and murine macrophages were shown to phagocytose RPEs through the pattern recognition receptor CD36. These in vitro data implicate scavenger receptors in the clearance of RPEs.     

Distribution of Leptospira Serogroups in Cattle Herds and Dogs in France

A retrospective study was conducted to identify and describe the distribution pattern of Leptospira serogroups in domestic animals in France. The population consisted of cattle herds and dogs with clinically suspected leptospirosis that were tested at the “Laboratoire des Leptospires” between 2008 and 2011. The laboratory database was queried for records of cattle and dogs in which seroreactivity in Leptospira microagglutination tests was consistent with a recent or current infection, excluding vaccine serogroups in dogs. A total of 394 cattle herds and 232 dogs were diagnosed with clinical leptospirosis, and the results suggested infection by the Leptospira serogroup Australis in 43% and 63%, respectively; by the Leptospira serogroup Grippotyphosa in 17% and 9%, respectively; and by the Leptospira serogroup Sejroe in 33% and 6%, respectively. This inventory of infecting Leptospira serogroups revealed that current vaccines in France are not fully capable of preventing the clinical form of the disease.Leptospirosis is a zoonotic bacterial disease that infects humans and domestic and wild mammals worldwide. This disease is important globally because of its worldwide distribution and its potentially fatal effects in humans. In Western Europe, France is one of the most affected countries, with a reported incidence of 0.37/100,000 inhabitants in 2011 (230 cases).¹The pathogenic agents of leptospirosis are bacteria from the genus Leptospira, specifically Leptospira interrogans sensu lato. Approximately 250 pathogenic serovars are now recognized and gathered into 24 antigenically related serogroups.² Although Leptospira can be maintained in wet environments for weeks, the main source of the bacteria is a wide range of domestic and wild mammals carrying specific Leptospira serogroups. Rodents are the predominant maintenance hosts of the bacteria, whereas infected dogs and cattle are less prevalent as hosts but may pose an important public health risk. Indeed, infectious urine excreted by infected domestic mammals³ and its potential contact with human mucosa could lead to Leptospira transmission. In addition, leptospirosis induces significant economic losses caused by reproductive disorders in cattle herds. Vaccines against certain Leptospira serovars are available for humans, dogs, and cattle, but the range of Leptospira serogroups is much broader compared with the range that vaccination protects against. Additionally, there is no cross-immunity between Leptospira serogroups.The vaccines available before 2012 for domestic animals in France only targeted dogs and included the serovars icterohaemorrhagiae and canicola. The canine vaccine has been augmented with the serovar grippotyphosa (Versican)^®, and a bovine vaccine that includes the serovar hardjo is now available. Previous studies have questioned the reliability of these vaccines and have reported that certain uncommon serogroups are increasingly found to be the cause of clinical leptospirosis in the United States⁴ and Europe.⁵ Therefore, understanding the distribution of currently circulating serogroups is critical for prophylactic purposes and vaccine design. This study provides an overview of Leptospira serogroups in France that are currently circulating in dogs and cattle herds showing signs suggestive of leptospirosis.From January 2008 to December 2011, veterinarians from across the country obtained samples from cattle and dogs showing clinical signs consistent with leptospirosis. Leptospirosis diagnosis was performed at the Laboratoire des Leptospires (Marcy L''Etoile, France) using a microagglutination test (MAT) as the reference test. The MAT was performed using a panel of antigens representing both ubiquitous serovars and locally prevalent serovars, with log2 dilution series between 1:40 and 1:5120 in dogs and between 1:50 and 1:6400 in cattle. The following Leptospira serogroups, with related serovars in parentheses, were tested in both species: Icterohemorrhagiae (icterohemorrhagiae, copenhageni), Australis (munchen, australis, Bratislava), Autumnalis (autumnalis, bim), Bataviae (bataviae), Grippotyphosa (grippotyphosa, vanderhoedoni), and Sejroe (sejroe, saxkoebing, hardjo, wolffi). Four additional Leptospira serogroups, Canicola (canicola), Panama (manama, mangus), Pomona (pomona, mozdok), and Pyrogenes (pyrogenes), were only tested in dogs.For cattle, no consensus is reported on the titer cut-off required to define an infected individual. Previously, the MAT showed a sensitivity and a specificity of 95% and 90%, respectively, at a cut-off ≥ 1:50 compared with microbiological cultures.⁶ From this, occurrences of cattle leptospirosis at the herd level were determined by identifying signs suggestive of leptospirosis, such as reproductive disorders and the presence of at least one cow with MAT titers ≥ 1:400. The cut-off was arbitrarily defined to increase the previously mentioned specificity. The predominant serogroup was then defined based on the maximum titer directed against one serogroup.⁷ Cross-reactivity between serogroups frequently occurs in MAT⁸ and results from a lack of specificity, especially from predominant non-specific immunoglobulin M (IgM) antibodies at the onset of infection.⁹ In these cases, MAT results involve maximum titers directed against two or more serogroups, thus preventing determination of the infecting serogroup. The MAT results including maximum titers directed against two serogroups are still informative by indicating one or the other as potentially circulating. In contrast, consideration of more than two possible circulating serogroups is speculative and uninformative. Therefore, among MAT results including maximum titers directed against two or more serogroups only the ones with two serogroups (“mix” results) were considered in this study.Most dogs monitored by veterinarians are vaccinated, which results in the development of seroreactivity directed against the icterohaemorrhagiae, copenhageni, and canicola serovars (called vaccine serovars). As previously described, in the current study, occurrences of canine leptospirosis were defined by signs suggestive of leptospirosis, such as acute renal failure or liver failure and at least one MAT titer of ≥ 1:640 against non-vaccine serovars.¹⁰ The predominant serogroup was defined similar to that in cattle. However, the MAT results for which vaccine serogroup titers were equal to non-vaccine titers were analyzed separately, to minimize the impact of vaccination on the results.To assess potential variation in the serogroup spread, mainland France was divided into six areas: North, Northwest, Northeast, Central, Southwest, and Southeast. The determination of the location of the different animals tested for the serogroups was based on the owner''s address.The MAT results of 394 cattle herds (570 cattle) suspected of having leptospirosis were used to determine the distribution of serogroups circulating in France. These MAT titer results ranged from 1:400 to 1:6400, with a median of 1:800. The predominant serogroups were Australis, Sejroe, and Grippotyphosa, regardless of the titer cut-off (Figure 1), and a similar serogroup ranking was observed in the six defined regions (Figure 2). In total, 29 herds were found to contain cows with MAT results suggesting different predominant serogroups. The combinations of Australis and Sejroe (N = 16) and of Sejroe and Grippotyphosa (N = 7) within a herd were predominant.Open in a separate windowFigure 1.The distribution of Leptospira serogroups among 394 cattle herds and 232 dogs with suspected clinical leptospirosis (excluding microagglutination test (MAT) results indicating high icterohaemorrhagiae, copenhageni, and canicola titers in dogs). The bar plots show the distribution of the serogroups among 570 cows and 232 dogs, considering the maximum MAT titer. Australis (AUS), Autumnalis (AUT), Bataviae (BAT), Grippotyphosa (GRI), Icterohaemorrhagiae (IH), Panama (PAN), Pomona (POM), Pyrogenes (PYR), and Sejroe (SJ), results including maximum titers directed against two serogroups (MIX).Open in a separate windowFigure 2.The spatial distribution of the infecting serogroups in 394 cattle herds and 229 dogs in six areas in mainland France: North, Northwest, Northeast, Central, Southwest, and Southeast. Three dogs were not considered because of missing location data, and one dog from Corse was excluded.The MAT results of 232 dogs were included in the distribution. The MAT titer results ranged between 1:640 and 1:5120, with a median of 1:2580. According to the bar plots, the predominant serogroups were Australis and Grippotyphosa, regardless of the titer cut-off. In particular, Australis was predominant in all six regions, whereas Grippotyphosa was only recorded in the four regions of western France (North, Northwest, Central, and Southwest).In all, 66 dogs with equal maximum titers directed against vaccine serogroups and one non-vaccine serogroup were additionally considered. The distribution of the non-vaccine serogroups was Australis (75%), Pyrogenes (14%), Grippotyphosa (5%), Sejroe (5%), and Panama (< 2%).This study examined the distribution of infecting serogroups involved in clinical bovine and canine leptospirosis. The serogroups Australis and Grippotyphosa were consistently predominant in the two species, and the results in dogs were consistent with the findings of a previous study in Germany.⁵ Considering the sensitivity (Se) estimates related to the cut-off defined in dogs (Se = 22–67%),¹⁰ the occurrence of leptospirosis may have been underestimated in this species. Nevertheless, the specificity (Sp) estimates in cattle (Sp ≥ 90%) and dogs (Sp = 69–100%) and the high median titers associated with signs suggestive of leptospirosis supported a diagnosis of current or recent Leptospira infection. As previously reported, the MAT correctly predicted the infecting serogroup in 46–86% of cases^7,11; the presumptive serogroup data appears to provide a broad overview of the serogroups commonly present in a population. Specifically, the majority of results (> 60% in cattle and > 72% in dogs) suggesting Australis and Grippotyphosa infections and the consistency of the distribution, regardless of the cut-offs used for the two species, provided substantial evidence for Australis and Grippotyphosa predominance in bovine and canine leptospirosis. These results also suggested that dogs and cattle could be exposed to the same sources of infection and/or the same infection pressure.The spatial distribution of the predominant serogroups in cattle appeared homogeneous in all six regions, whereas in dogs, the distribution of Grippotyphosa was heterogeneous. This finding suggested that in contrast to cattle, the exposure of dogs to certain serogroups varied within mainland France.The results of this study indicated that Sejroe was responsible for 30% of cases of bovine clinical leptospirosis. This finding suggested that the available bovine vaccine targeting this serogroup is capable of preventing one-third of the clinical cases. Nevertheless, additional serogroups, such as Australis and, to a lesser extent, Grippotyphosa, should be included to eliminate most Leptospira-related diseases in cattle. For dogs, it would be important to include Australis antigens in a canine vaccine to aid in preventing infection with the serogroup responsible for most clinical cases of leptospirosis in dogs in France.This inventory of infecting Leptospira serogroups circulating in cattle and dogs should be considered when designing future vaccines to improve leptospirosis prevention. As part of a “one health” approach, this could lead to reduce human cases exposed to potentially infected domestic animals.     

Pulsed-Field Gel Electrophoresis Is More Efficient than Ribotyping and Random Amplified Polymorphic DNA Analysis in Discrimination of Pasteurella haemolytica Strains

One hundred thirty-three strains of Pasteurella haemolytica of both biotypes (90 and 43 strains of biotypes A and T, respectively) and almost all the serotypes were subjected to ribotyping, random amplified polymorphic DNA (RAPD) analysis, and pulsed-field gel electrophoresis (PFGE) analysis for epidemiological purposes. A total of 15 patterns recorded as ribotypes HA to HO were found for the P. haemolytica biotype A strains, with ribotypes HA, HC, and HD being encountered most often (66 strains [74%]); and 20 ribotypes, designated HA′ to HT′, that were clearly distinct from those observed for biotype A strains were observed for strains of biotype T. RAPD analysis generated a total of 44 (designated Rp1 to Rp44) and 15 (designated Rp1′ to Rp 15′) unique RAPD patterns for biogroup A and biogroup T, respectively. Analysis of the data indicated that a given combined ribotype-RAPD pattern could be observed for biotype A strains of different serotypes, whatever the zoological or geographic origin, whereas this was not the case for biotype T strains. PFGE appeared to be more efficient in strain discrimination since selected strains from various zoological or geographical origins harboring the same ribotype-RAPD group were further separated into unique entities.     

Use of handheld computers with global positioning systems for probability sampling and data entry in household surveys

We introduce an innovative method that uses personal digital assistants (PDAs) equipped with global positioning system (GPS) units in household surveys to select a probability-based sample and perform PDA-based interviews. Our approach uses PDAs with GPS to rapidly map all households in selected areas, choose a random sample, and navigate back to the sampled households to conduct an interview. We present recent field experience in two large-scale nationally representative household surveys to assess insecticide-treated bed net coverage as part of malaria control efforts in Africa. The successful application of this method resulted in statistically valid samples; quality-controlled data entry; and rapid aggregation, analyses, and availability of preliminary results within days of completing the field work. We propose this method as an alternative to the Expanded Program on Immunization cluster sample method when a fast, statistically valid survey is required in an environment with little census information at the enumeration area level.     

The epidemiology of Neisseria meningitidis meningitis in Togo during 2003-2005

Few reports documenting the epidemiology of Neisseria meningitidis (Nm) serogroup W135 exist, and none from Togo. During 2003-2005, we conducted acute bacterial meningitis surveillance at three major reference hospitals in Togo. Of 116 Nm identified, 83 (71%) were NmA, 23 (20%) were NmW135, and 10 (9%) did not have a serogroup identified. Nine percent of NmW135 cases and 35% of NmA cases occurred among those aged 15 years or older. The two hospitals in central Togo reported 23% of all Nm cases and 78% of NmW135 cases. Twelve of the 23 NmW135 cases occurred during February-March 2003, while the remaining 11 occurred sporadically over the remaining 18 months of the study. NmW135 meningitis showed pronounced temporal and geographic clustering and occurred almost exclusively among those younger than 15 years old. By the 2004-2005 epidemic season, NmW135 had largely disappeared from Togo for unknown reasons.     

A case of Pasteurella multocida peritoneal dialysis-associated peritonitis and review of the literature.

OBJECTIVES: Two episodes of peritoneal dialysis-associated peritonitis, which occurred four months apart and were both due to Pasteurella multocida, were noted in a 73 year old woman. This report aims to describe the clinical history of these episodes and the microbiological investigations that were undertaken. The relevant literature will also be discussed. METHODS AND RESULTS: Basic microbiological tests identified the organism as Pasteurella multocida, and further work at a specialist laboratory classified it as Pasteurella multocida subsp. multocida. Pulsed field gel electrophoresis confirmed that the strains isolated from the two clinical episodes originated from the same clone. A literature search was performed, looking particularly for patients who experienced more than one episode of peritonitis caused by Pasteurella spp, whether due to recurrence or re-infection. CONCLUSIONS: It is likely that the infection resulted from a domestic cat, as there was evidence of a cat bite to the dialysis tubing in the period between the two episodes. Re-infection with two identical strains of pasteurella is more probable than relapse, for reasons discussed. Strict hygiene and avoiding contact between dialysis tubing and domestic animals must be emphasised to try to prevent pasteurella and other animal-associated infections in this already vulnerable population.     

Intestinal Absorption and Permeability in Human Immunodeficiency Virus-Infected Patients

Background: Impaired intestinal function could account for diarrhoea and weight loss, which are common features of advanced human immunodeficiency virus (HIV) infection. Methods: We assessed intestinal permeability to lactulose and mannitol and absorption of D-xylose in 96 HIV-infected patients (group I: asymptomatic subjects (CDC-A); group II: symptomatic subjects (CDC-B or C) without body weight loss and/or diarrhoea; group III: 25 acquired immunodeficiency syndrome (AIDS) patients (CDC-C) with severe body weight loss and/or diarrhoea) and 10 healthy subjects as controls. Results: An incremental decrease in urinary D-xylose recoveries was observed, with all groups statistically different from each other. Impaired intestinal permeability was only found in patients of group III (statistically different from all other groups). Conclusions: These findings suggest a loss of intestinal functional absorptive surface as HIV disease progresses. This process may be present at the early stage of infection. Impaired intestinal permeability is observed later in AIDS patients when digestive signs are present, particularly diarrhoea.     

Hyperhomocysteinemia among ischemic stroke victims in the teaching hospital of Lomé

Hyperhomocysteinemia is an independent vascular risk factor involved in ischaemic stroke. Aim of this study was to evaluate the prevalence of hyperhomocysteinemia and the role of the metabolic determinants in ischaemic stroke. The study concerned 183?patients in the Department of neurology of the teaching hospital of Lome. The diagnosis of stroke was made on clinical and brain CT scan arguments. The dosage of homocysteinemia was carried out by the immunoenzymatic method (Abbott Diagnostic). Among 183?patients, 111 (61%) had a hyperhomocysteinemia. The total average homocysteinemia was of 22.0 μmol/L. The average homocysteinemia among men was of 22.4 μmol/L (5.2-198.0) and 18.80 μmol/L (4.2-50) among women with a positive correlation (P = 0.049 and 0.01) between homocysteinemia and the age among the men and women. The average homocysteinemia was of 17.2 μmol/L in the large ischaemic stroke; 23.0?μmol/L when associated with lacunes and 32.8 μmol/L when associated with lacunes and leucoaraiosis (p = 0.001). In conclusion, the hospital prevalence of the hyperhomocysteinemia was of 61%. Hyperhomocysteinemia was the second vascular risk factor after arterial hypertension in term of prevalence, probably from nutritional cause.     

Epidemiology and antibiotic resistance of bacterial meningitis in Dapaong,northern Togo

ObjectiveTo assess the seasonality of the bacterial meningitis and the antibiotic resistance of incriminated bacteria over the last three years in the northern Togo.MethodsFrom January 2007 to January 2010, 533 cerebrospinal fluids (CSF) samples were collected from patients suspected of meningitis in the Regional Hospital of Dapaong (northern Togo). After microscopic examination, samples were cultured for bacterial identification and antibiotic susceptibility.ResultsThe study included 533 patients (306 male and 227 female) aged from 1 day to 55 years [average age (13.00±2.07) years]. Bacterial isolation and identification were attempted for 254/533 (47.65%) samples. The bacterial species identified were: Neisseria meningitidis A (N. meningitidis A) (58.27%), Neisseria meningitidis W135 (N. meningitidis W135) (7.09%), Streptococcus pneumoniae (S. pneumoniae) (26.77%), Haemophilus influenza B (H. influenza B) (6.30%) and Enterobacteriaceae (1.57%). The results indicated that bacterial meningitis occur from November to May with a peak in February for H. influenzae and S. pneumoniae and March for Neisseriaceae. The distribution of positive CSF with regards to the age showed that subjects between 6 and 12 years followed by subjects of 0 to 5 years were most affected with respective frequencies of 67.82% and 56.52% (P<0.001). Susceptibility tests revealed that bacteria have developed resistance to several antibiotics including aminosides (resistance rate >20% for both bacterial strains), macrolides (resistance rate > 30% for H. influenzae) quinolones (resistance rate >15% for H. influenzae and N. meningitidis W135). Over three years, the prevalence of S. pneumoniae significantly increased from 8.48% to 73.33% (P<0.001), while the changes in the prevalence of H. influenzae B were not statistically significant: 4.24%, vs. 8.89%, (P = 0.233).ConclusionsOur results indicate that data in African countries differ depending on geographical location in relation to the African meningitis belt. This underlines the importance of epidemiological surveillance of bacterial meningitis.