High Seroprevalence for Spotted Fever Group Rickettsiae,Is Associated with Higher Temperatures and Rural Environment in Mbeya Region,Southwestern Tanzania

Background

Rickettsioses are endemic in sub-Sahara Africa. Burden of disease, risk factors and transmission are hitherto sparsely described.

Methods

From the EMINI (Evaluating and Monitoring the Impact of New Interventions) population cohort, we randomly selected 1,228 persons above the age of 5 years from the nine participating communities in Mbeya region, Southwestern Tanzania, stratified by age, altitude of residence and ownership of domestic mammals, to conduct a cross-sectional seroprevalence study in. The aim was to estimate the seroprevalence of IgG antibodies against Spotted Fever Group (SFG) rickettsiae and to assess socioeconomic and environmental risk factors. Serology (indirect immunofluorescence) was performed at a dilution of 1:64.

Results

SFG-seropositivity in the cohort was found to be 67.9% (range among nine sites: 42.8–91.4%). Multivariable analysis revealed an association with age (prevalence ratio, PR per 10 years: 1.08; 95% CI 1.06–1.10), warmer temperatures (PR per °C: 1.38; 1.11–1.71), male gender (PR 1.08; 1.00–1.16), and low population density (PR per 1.000 persons/km²increase 0.96; 0.94–0.99). At higher elevations, higher cattle density was associated with higher seroprevalence.

Conclusion

SFG rickettsial infection seems to be common in the more rural population of Mbeya Region. Spread seems to be further limited by temperature and higher elevation. Examination of the contribution of SFG to febrile illnesses seems warranted in a prospective study to estimate the disease burden in the population. This will also allow determination of the causative pathogens.     

The Seroprevalence of Hepatitis C Antibodies in Immigrants and Refugees from Intermediate and High Endemic Countries: A Systematic Review and Meta-Analysis

MethodsFour electronic databases were searched from database inception until June 17, 2014 for studies reporting the prevalence of HCV antibodies among migrants. Seroprevalence estimates were pooled with a random-effect model and were stratified by age group, region of origin and migration status and a meta-regression was modeled to explore heterogeneity.ResultsData from 50 studies representing 38,635 migrants from all world regions were included. The overall anti-HCV prevalence (representing previous and current infections) was 1.9% (95% CI, 1.4–2.7%, I² 96.1). Older age and region of origin, particularly Sub-Saharan Africa, Asia, and Eastern Europe were the strongest predictors of HCV seroprevalence. The estimated HCV seroprevalence of migrants from these regions was >2% and is higher than that reported for most host populations.ConclusionAdult migrants originating from Asia, Sub-Saharan Africa and Eastern Europe are at increased risk for HCV and may benefit from targeted HCV screening.     

Seroprevalence of Toxoplasma gondii in pigs in Southwestern China

The seroprevalence of toxoplasmosis in pigs was investigated in Yunnan province, Southwestern China between March 2008 and January 2009. A total of 831 serum samples were collected from 9 counties and assayed for Toxoplasma gondii antibodies by indirect haemagglutination (IHA) test. Antibodies to T. gondii were found in 16.97% (141/831) with slaughter pigs having the highest rate (22.28%), followed by breeding sows (16.59%). The results of the present survey indicated that infection with T. gondii in pigs is widely spread in China, including the Yunnan province, and is of public health concern.     

Avian Influenza Seroprevalence and Biosecurity Risk Factors in Maryland Backyard Poultry: A Cross-Sectional Study

Major implications on a country''s economy, food source, and public health. With recent concern over the highly pathogenic avian influenza outbreaks around the world, government agencies are carefully monitoring and inspecting live bird markets, commercial flocks, and migratory bird populations. However, there remains limited surveillance of non-commercial poultry. Therefore, a cross-sectional study was conducted in backyard poultry flocks using a convenience sampling method across three regions of Maryland from July 2011 to August 2011. The objective of this study was to develop a better understanding of the ecology and epidemiology of avian influenza by investigating the prevalence and seroprevalence in this potentially vulnerable population and by evaluating biosecurity risk factors associated with positive findings. Serum, tracheal, and cloacal swabs were randomly collected from 262 birds among 39 registered premises. Analysis indicated bird and flock seroprevalence as 4.2% (11/262) and 23.1% (9/39), respectively. Based on RT-qPCR analysis, none of the samples were found to be positive for AI RNA and evidence of AI hemagglutinin subtypes H5, H7, or H9 were not detected. Although no statistically significant biosecurity associations were identified (p≤0.05), AI seroprevalence was positively associated with exposure to waterfowl, pest control, and location. AI seropositive flocks exposed to waterfowl were 3.14 times as likely to be AI seropositive than those not exposed (p = 0.15). AI seropositive flocks that did not use pest control were 2.5 times as likely to be AI seropositive compared to those that did and AI seropositive flocks located in the Northern region of Maryland were 2.8 times as likely to be AI seropositive than those that were located elsewhere.     

Seroprevalence of Chikungunya virus and living conditions in Feira de Santana,Bahia-Brazil

BackgroundChikungunya is an arbovirus, transmitted by Aedes mosquitoes, which emerged in the Americas in 2013 and spread rapidly to almost every country on this continent. In Brazil, where the first cases were detected in 2014, it currently has reached all regions of this country and more than 900,000 cases were reported. The clinical spectrum of chikungunya ranges from an acute self-limiting form to disabling chronic forms. The purpose of this study was to estimate the seroprevalence of chikungunya infection in a large Brazilian city and investigate the association between viral circulation and living condition.Methodology/principal findingsWe conducted a population-based ecological study in selected Sentinel Areas (SA) through household interviews and a serologic survey in 2016/2017. The sample was of 1,981 individuals randomly selected. The CHIKV seroprevalence was 22.1% (17.1 IgG, 2.3 IgM, and 1.4 IgG and IgM) and varied between SA from 2.0% to 70.5%. The seroprevalence was significantly lower in SA with high living conditions compared to SA with low living condition. There was a positive association between CHIKV seroprevalence and population density (r = 0.2389; p = 0.02033).Conclusions/significanceThe seroprevalence in this city was 2.6 times lower than the 57% observed in a study conducted in the epicentre of the CHIKV epidemic of this same urban centre. So, the herd immunity in this general population, after four years of circulation of this agent is relatively low. It indicates that CHIKV transmission may persist in that city, either in endemic form or in the form of a new epidemic, because the vector infestation is persistent. Besides, the significantly lower seroprevalences in SA of higher Living Condition suggest that beyond the surveillance of the disease, vector control and specific actions of basic sanitation, the reduction of the incidence of this infection also depends on the improvement of the general living conditions of the population.     

Hookworm Infection and Environmental Factors in Mbeya Region,Tanzania: A Cross-Sectional,Population-Based Study

Background

Hookworm disease is one of the most common infections and cause of a high disease burden in the tropics and subtropics. Remotely sensed ecological data and model-based geostatistics have been used recently to identify areas in need for hookworm control.

Methodology

Cross-sectional interview data and stool samples from 6,375 participants from nine different sites in Mbeya region, south-western Tanzania, were collected as part of a cohort study. Hookworm infection was assessed by microscopy of duplicate Kato-Katz thick smears from one stool sample from each participant. A geographic information system was used to obtain remotely sensed environmental data such as land surface temperature (LST), vegetation cover, rainfall, and elevation, and combine them with hookworm infection data and with socio-demographic and behavioral data. Uni- and multivariable logistic regression was performed on sites separately and on the pooled dataset.

Principal Findings

Univariable analyses yielded significant associations for all ecological variables. Five ecological variables stayed significant in the final multivariable model: population density (odds ratio (OR) = 0.68; 95% confidence interval (CI) = 0.63–0.73), mean annual vegetation density (OR = 0.11; 95% CI = 0.06–0.18), mean annual LST during the day (OR = 0.81; 95% CI = 0.75–0.88), mean annual LST during the night (OR = 1.54; 95% CI = 1.44–1.64), and latrine coverage in household surroundings (OR = 1.02; 95% CI = 1.01–1.04). Interaction terms revealed substantial differences in associations of hookworm infection with population density, mean annual enhanced vegetation index, and latrine coverage between the two sites with the highest prevalence of infection.

Conclusion/Significance

This study supports previous findings that remotely sensed data such as vegetation indices, LST, and elevation are strongly associated with hookworm prevalence. However, the results indicate that the influence of environmental conditions can differ substantially within a relatively small geographic area. The use of large-scale associations as a predictive tool on smaller scales is therefore problematic and should be handled with care.     

Seroprevalence to the Antigens of Taenia solium Cysticercosis among Residents of Three Villages in Burkina Faso: A Cross-Sectional Study

Background

There is limited published information on the prevalence of human cysticercosis in West Africa. The aim of this pilot study was to estimate the prevalence of Taenia solium cysticercosis antigens in residents of three villages in Burkina Faso.

Methods/Principal Findings

Three villages were selected: The village of Batondo, selected to represent villages where pigs are allowed to roam freely; the village of Pabré, selected to represent villages where pigs are usually confined; and the village of Nyonyogo, selected because of a high proportion of Muslims and limited pig farming. Clustered random sampling was used to select the participants. All participants were asked to answer an interview questionnaire on socio-demographic characteristics and to provide a blood sample. The sera were analysed using an AgELISA. The prevalence of “strong” seropositive results to the presence of antigens of the larval stages of T. solium was estimated as 10.3% (95%CI: 7.1%–14.3%), 1.4% (0.4%–3.5%) and 0.0% (0.0%–2.1%) in the 763 participants who provided a blood sample in Batondo, Pabré and Nyonyogo, respectively. The prevalence of “weak” seropositive test results to the presence of antigens of the larval stages of T. solium was 1.3% (0.3%–3.2%), 0.3% (0.0%–1.9%) and 4.5% (2.0%–8.8%) in Batondo, Pabré and Nyonyogo, respectively. The multivariate logistic regression, which included only Batondo and Pabré, showed that village, gender, and pork consumption history were associated with AgELISA seroprevalence.

Conclusions/Significance

This study illustrates two major points: 1) there can be large variation in the prevalence of human seropositivity to the presence of the larval stages of T. solium cysticercosis among rural areas of the same country, and 2) the serological level of the antigen, not just whether it is positive or negative, must be considered when assessing prevalence of human cysticercosis antigens.     

Malaria and Helminth Co-Infections in School and Preschool Children: A Cross-Sectional Study in Magu District,North-Western Tanzania

Background

Malaria, schistosomiasis and soil transmitted helminth infections (STH) are important parasitic infections in Sub-Saharan Africa where a significant proportion of people are exposed to co-infections of more than one parasite. In Tanzania, these infections are a major public health problem particularly in school and pre-school children. The current study investigated malaria and helminth co-infections and anaemia in school and pre-school children in Magu district, Tanzania.

Methodology

School and pre-school children were enrolled in a cross-sectional study. Stool samples were examined for Schistosoma mansoni and STH infections using Kato Katz technique. Urine samples were examined for Schistosoma haematobium using the urine filtration method. Blood samples were examined for malaria parasites and haemoglobin concentrations using the Giemsa stain and Haemoque methods, respectively.

Principal Findings

Out of 1,546 children examined, 1,079 (69.8%) were infected with one or more parasites. Malaria-helminth co-infections were observed in 276 children (60% of all children with P. falciparum infection). Malaria parasites were significantly more prevalent in hookworm infected children than in hookworm free children (p = 0.046). However, this association was non-significant on multivariate logistic regression analysis (OR = 1.320, p = 0.064). Malaria parasite density decreased with increasing infection intensity of S. mansoni and with increasing number of co-infecting helminth species. Anaemia prevalence was 34.4% and was significantly associated with malaria infection, S. haematobium infection and with multiple parasite infections. Whereas S. mansoni infection was a significant predictor of malaria parasite density, P. falciparum and S. haematobium infections were significant predictors of anaemia.

Conclusions/Significance

These findings suggest that multiple parasite infections are common in school and pre-school children in Magu district. Concurrent P. falciparum, S. mansoni and S. haematobium infections increase the risk of lower Hb levels and anaemia, which in turn calls for integrated disease control interventions. The associations between malaria and helminth infections detected in this study need further investigation.     

Seroprevalence of Fecal-Oral Transmitted Hepatitis A and E Virus Antibodies in Burkina Faso

Hepatitis A virus (HAV) and hepatitis E virus (HEV) infections occur chiefly as a result of unhygienic conditions. The purpose of this study was to assess the seroprevalence of antibodies to both viruses in central Burkina Faso in the absence of a recorded hepatitis epidemic. Serum samples from 178 blood donors (131 males and 47 females) and from 189 pregnant women were collected from November 2010 to March 2012, at blood banks and medical centers in Burkina Faso. An immunochromatography test was used to screen for Anti-HAV IgM and IgG in a subgroup of 91 blood donors and 100 pregnant women. The seroprevalence of anti-HAV IgG was 14.3% [CI95, 7.1–21.4%] for all blood donors and 23% [CI95, 14.8–31.2%] for pregnant women. Anti-HEV IgG were detected using the ELISA kits Dia.pro and Wantai and were found in 19.1% [CI95, 13.3–24.9%] of the blood donors and 11.6% [CI95, 7.1–16.2%] of the pregnant women. The seroprevalences of anti-HAV and anti-HEV IgGs did not differ significantly between men and women blood donors. Anti-HAV IgM was detected in 3.3% of the blood donors and in 2% of the pregnant women. These findings for asymptomatic individuals indicate that the HAV and HEV circulate at low but significant levels. This is the first evaluation of the acute hepatitis virus burden in Burkina Faso and the underlying epidemiologic status of the population.     

Sero-Prevalence and Cross-Reactivity of Chikungunya Virus Specific Anti-E2EP3 Antibodies in Arbovirus-Infected Patients

Chikungunya virus (CHIKV) and clinically-related arboviruses cause large epidemics with serious economic and social impact. As clinical symptoms of CHIKV infections are similar to several flavivirus infections, good detection methods to identify CHIKV infection are desired for improved treatment and clinical management. The strength of anti-E2EP3 antibody responses was explored in a longitudinal study on 38 CHIKV-infected patients. We compared their anti-E2EP3 responses with those of patients infected with non-CHIKV alphaviruses, or flaviviruses. E2EP3 cross-reactive samples from patients infected with non-CHIKV viruses were further analyzed with an in vitro CHIKV neutralization assay. CHIKV-specific anti-E2EP3 antibody responses were detected in 72% to 100% of patients. Serum samples from patients infected with other non-CHIKV alphaviruses were cross-reactive to E2EP3. Interestingly, some of these antibodies demonstrated clearly in vitro CHIKV neutralizing activity. Contrastingly, serum samples from flaviviruses-infected patients showed a low level of cross-reactivity against E2EP3. Using CHIKV E2EP3 as a serology marker not only allows early detection of CHIKV specific antibodies, but would also allow the differentiation between CHIKV infections and flavivirus infections with 93% accuracy, thereby allowing precise acute febrile diagnosis and improving clinical management in regions newly suffering from CHIKV outbreaks including the Americas.     

Field Evaluation of the Cepheid GeneXpert Chlamydia trachomatis Assay for Detection of Infection in a Trachoma Endemic Community in Tanzania

Purpose

To determine the sensitivity, specificity, and field utility of the Cepheid GeneXpert Chlamydia trachomatis (CT) Assay (GeneXpert) for ocular chlamydia infection compared to Roche Amplicor CT assay (Amplicor).

Methods

In a trachoma-endemic community in Kongwa Tanzania, 144 children ages 0 to 9 were surveyed to assess clinical trachoma and had two ocular swabs taken. One swab was processed at Johns Hopkins University, Baltimore MD, using Amplicor, (Roche Molecular Diagnostics) and the other swab was processed at a field station in Kongwa using the GeneXpert Chlamydia trachomatis/Neisseria gonorrhoeae assay (Cepheid). The sensitivity and specificity of GeneXpert was compared to the Amplicor assay.

Results

Of the 144 swabs taken the prevalence of follicular trachoma by clinical exam was 43.7%, and by evidence of infection according to Amplicor was 28.5%. A total of 17 specimens (11.8%) could not be processed by GeneXpert in the field due to lack of sample volume, other specimen issues or electricity failure. The sensitivity of GeneXpert when compared to Amplicor was 100% and the specificity was 95%. The GeneXpert test identified more positives in individuals with clinical trachoma than Amplicor, 55% versus 52%.

Conclusion

The GeneXpert test for C. trachomatis performed with high sensitivity and specificity and demonstrated excellent promise as a field test for trachoma control.     

Unique Epitopes Recognized by Antibodies Induced in Chikungunya Virus-Infected Non-Human Primates: Implications for the Study of Immunopathology and Vaccine Development

Chikungunya virus (CHIKV) is an Alphavirus that causes chronic and incapacitating arthralgia in humans. Although patient cohort studies have shown the production of CHIKV specific antibodies, the fine specificity of the antibody response against CHIKV is not completely defined. The macaque model of CHIKV infection was established due to limitations of clinical specimens. More importantly, its close relation to humans will allow the study of chronic infection and further identify important CHIKV targets. In this study, serum samples from CHIKV-infected macaques collected at different time-points post infection were used to characterize the antibody production pattern and kinetics. Results revealed that anti-CHIKV antibodies were neutralizing and the E2 glycoprotein, Capsid, nsP1, nsP3 and nsP4 proteins were targets of the anti-CHIKV antibody response in macaques. Furthermore, linear B-cell epitopes recognized by these anti-CHIKV antibodies were identified, and mapped to their structural localization. This characterizes the specificity of anti-CHIKV antibody response in macaques and further demonstrates the importance of the different regions in CHIKV-encoded proteins in the adaptive immune response. Information from this study provides critical knowledge that will aid in the understanding of CHIKV infection and immunity, vaccine design, and pre-clinical efficacy studies.     

Canine Antibodies against Salivary Recombinant Proteins of Phlebotomus perniciosus: A Longitudinal Study in an Endemic Focus of Canine Leishmaniasis

BackgroundPhlebotomine sand flies are vectors of Leishmania parasites. During blood feeding, sand flies deposit into the host skin immunogenic salivary proteins which elicit specific antibody responses. These anti-saliva antibodies enable an estimate of the host exposure to sand flies and, in leishmaniasis endemic areas, also the risk for Leishmania infections. However, the use of whole salivary gland homogenates as antigen has several limitations, and therefore, recombinant salivary proteins have been tested to replace them in antibody detection assays. In this study, we have used for the first time sand fly salivary recombinant proteins in a longitudinal field study on dogs.ConclusionsThese results suggest that P. perniciosus rSP03B protein is a valid alternative to whole saliva and could be used in large-scale serological studies. This novel method could be a practical and economically-sound tool to detect the host exposure to sand fly bites in CanL endemic areas.     

Soil-Transmitted Helminths in Southwestern China: A Cross-Sectional Study of Links to Cognitive Ability,Nutrition, and School Performance among Children

BackgroundEmpirical evidence suggests that the prevalence of soil-transmitted helminth (STH) infections in remote and poor rural areas is still high among children, the most vulnerable to infection. There is concern that STH infections may detrimentally affect children’s healthy development, including their cognitive ability, nutritional status, and school performance. Medical studies have not yet identified the exact nature of the impact STH infections have on children. The objective of this study is to examine the relationship between STH infections and developmental outcomes among a primary school-aged population in rural China.Conclusions/SignificanceWe find that STH infection still poses a significant health challenge among children living in poor, rural, ethnic areas of southwest China. Given the important linkages we find between STH infection and a number of important child health and educational outcomes, we believe that our results will contribute positively to the debate surrounding the recent Cochrane report.     

High Seroprevalence for Rickettsia rickettsii in Equines Suggests Risk of Human Infection in Silent Areas for the Brazilian Spotted Fever

Equines play a role in the epidemiology of Brazilian spotted fever (BSF) since they are a primary host for the tick Amblyomma sculptum. We studied the seroprevalence for three species of Rickettsia in equines in four endemic (with human cases) and in four non-endemic areas (no human cases) in the Piracicaba River Basin, São Paulo, Brazil. A serological survey of 504 equines was performed: around 63 animals were sampled in each area and tested through indirect immunofluorescence assay for R. rickettsii, R. parkeri, and R. bellii in 2012–2013. Blood samples were seropositive for 183 equines (36.3%) in which 73 (39.9%) were from non-endemic areas. In the studied sites equines were highly exposed to Rickettsia infection ranging from 6.1% to 54.7%, with Geometric Mean Titers greater in endemic area (p = 0.012). Results suggest that Rickettsia may be more widespread than the surveillance of BSF has detected. These results highlight the need to include data on the seroprevalence of sentinel animals to improve human diagnoses and surveillance in areas with no reported human cases.     

Seroprevalence of Antibodies Against Paracoccidioides Spp. in Captive Dolphins from Three Aquaria in Japan

Mycopathologia - The skin disease paracoccidioidomycosis ceti occurs in several dolphin species globally. Infection by the unculturable fungi Paracoccidioides brasilensis or other Paracoccidioides...     

Longitudinal Monitoring of the Development of Antifilarial Antibodies and Acquisition of Wuchereria bancrofti in a Highly Endemic Area of Haiti

Antifilarial antibody testing has been established as a sensitive and specific method of diagnosing lymphatic filariasis. However, the development of serological responses to specific filarial antigens and their relationship to acquisition of infection is poorly understood. In order to evaluate whether the development of antigen specific antifilarial antibodies precedes microfilaremia and antigenemia, we compared the antibody responses of serum samples collected between 1990 and 1999 from a cohort of 142 Haitian children followed longitudinally. Antigen status was determined using the Og4C3 ELISA and the presence of microfilaremia was detected using microscopy. Antibody responses to Wb123, a Wuchereria bancrofti L3 antigen, were measured using a Luciferase Immunoprecipitation System (LIPS) assay. Antibody responses to Bm14 and Bm33, Brugia malayi antigens and to a major surface protein (WSP) from Wolbachia were analyzed using a multiplex bead assay. Over follow-up, 80 (56%) of the children became antigen-positive and 30 (21%) developed microfilaremia. Detectable antibody responses to Bm14, Bm33, Wb123, and WSP developed in 95%, 100%, 92%, and 29% of children, respectively. With the exception of WSP, the development of antibody responses generally preceded detection of filarial antigen. Our results show that antifilarial antibody responses can serve as an important epidemiological indicator in a sentinel population of young children and thus, may be valuable as tool for surveillance in the context of lymphatic filariasis elimination programs.     

Dried-Blood Spots: A Cost-Effective Field Method for the Detection of Chikungunya Virus Circulation in Remote Areas

Background

In 2005, there were outbreaks of febrile polyarthritis due to Chikungunya virus (CHIKV) in the Comoros Islands. CHIKV then spread to other islands in the Indian Ocean: La Réunion, Mauritius, Seychelles and Madagascar. These outbreaks revealed the lack of surveillance and preparedness of Madagascar and other countries. Thus, it was decided in 2007 to establish a syndrome-based surveillance network to monitor dengue-like illness.

Objective

This study aims to evaluate the use of capillary blood samples blotted on filter papers for molecular diagnosis of CHIKV infection. Venous blood samples can be difficult to obtain and the shipment of serum in appropriate temperature conditions is too costly for most developing countries.

Methodology and principal findings

Venous blood and dried-blood blotted on filter paper (DBFP) were collected during the last CHIKV outbreak in Madagascar (2010) and as part of our routine surveillance of dengue-like illness. All samples were tested by real-time RT-PCR and results with serum and DBFP samples were compared for each patient. The sensitivity and specificity of tests performed with DBFP, relative to those with venous samples (defined as 100%) were 93.1% (95% CI:[84.7–97.7]) and 94.4% (95% CI:[88.3–97.7]), respectively. The Kappa coefficient 0.87 (95% CI:[0.80–0.94]) was excellent.

Conclusion

This study shows that DBFP specimens can be used as a cost-effective alternative sampling method for the surveillance and monitoring of CHIKV circulation and emergence in developing countries, and probably also for other arboviruses. The loss of sensitivity is insignificant and involved a very small number of patients, all with low viral loads. Whether viruses can be isolated from dried blood spots remains to be determined.