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Domestic animals and epidemiology of visceral leishmaniasis, Nepal
No full textOn the Indian subcontinent, visceral leishmaniasis (VL) is considered an anthroponosis. To determine possible reasons for its persistence during interepidemic periods, we mapped Leishmania infections among healthy persons and animals in an area of active VL transmission in Nepal. During 4 months (September 2007-February 2008), blood was collected from persons, goats, cows, and buffaloes in 1 village. Leishmania infections were determined by using PCR. We found infections among persons (6.1%), cows (5%), buffaloes (4%), and goats (16%). Data were georeferenced and entered into a geographic information system. The bivariate K-function results indicated spatial clustering of Leishmania spp.-positive persons and domestic animals. Classification tree analysis determined that among several possible risk factors for Leishmania infection among persons, proximity of Leishmania spp.-positive goats ranked first. Although our data do not necessarily mean that goats constitute a reservoir host of L. donovani, these observations indicate the need for further investigation of goats' possible role in VL transmission
Age-related infection and transmission patterns of human cysticercosis
No full textNeurocysticercosis is recognised as an important but neglected cause of epilepsy in developing countries where the parasite occurs. Data on the transmission dynamics of the parasite in endemic areas are scarce. Individuals living in these areas are likely to be highly exposed to the parasite, but relatively few of them develop active infections. The present study aimed to describe and gain insights into changes in antibody responses and infection patterns related to age and/or gender in a south Ecuadorian rural population by combining antibody and antigen serological data with demographic characteristics. In 25% of the population, antibodies to Taenia solium cysticerci were detected whilst 2.9% had circulating parasite antigens. The proportion of antibody-positive individuals increased significantly until the age of 40years to become stable in older individuals. A rule-based simulation model was developed to explain these variations and to reflect the dynamics of exposure to, and transmission of, the parasite. In contrast, the proportion of people presenting circulating parasite antigens, reflecting an active infection, was significantly higher in people older than 60years. Immunosenescence could explain such an observation since a weaker immune system in the elderly would facilitate the establishment and maintenance of viable cysticerci compared with fully immunocompetent younger individuals. This work points out the role of the immune system in the development of cysticercosis within an exposed population and highlights new essential issues in understanding the transmission dynamics of the parasite, its incidence and the resulting immunological response at a population level. Copyright 2009 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved
Evaluation of host genetic and viral factors as surrogate markers for HTLV-1-associated myelopathy/tropical spastic paraparesis in Peruvian HTLV-1-infected patients
No full textHuman T-lymphotropic virus 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a complication that affects up to 5% of HTLV-1-infected individuals. Several host genetic and viral factors have been associated with the risk of HAM/TSP. The aim of this study was to evaluate the performance of a prognostic model for HAM/TSP developed in Japan in a Peruvian population of 71 HAM/TSP patients and 94 asymptomatic carriers (ACs). This model included age, proviral load (PVL), the presence of HLA-A*02 and HLA-Cw*08 alleles, SDF-1 +801, and TNF-alpha -863 polymorphisms, and viral subgroup. We describe frequencies for the four host genetic markers and demonstrate the presence of the HTLV-1 tax B subgroup in Peru. Using cross-validation, we show that the predictive ability of the prognostic model, as characterized by the area under the receiver-operating characteristic curve (AUC), does not differ from a model containing PVL only (both AUC = 0.74). We found some suggestive evidence of a protective effect of the HLA-A*02 allele but failed to replicate the associations with the other three genetic markers and with viral subgroup. A logistic model containing PVL, age, gender, and HLA-A*02 provided the best predictive ability in the Peruvian cohort (AUC = 0.79)
Wat kan het lokale beleid betekenen voor de mantelzorger? Een studie of mantelzorg voor ouderen in de Oost-Vlaamse gemeente Kruibeke
No full textMalaria rapid diagnostic tests: Plasmodium falciparum infections with high parasite densities may generate false positive Plasmodium vivax pLDH lines
No full textBACKGROUND: Most malaria rapid diagnostic tests (RDTs) detect Plasmodium falciparum and an antigen common to the four species. Plasmodium vivax-specific RDTs target P. vivax-specific parasite lactate dehydrogenase (Pv-pLDH). Previous observations of false positive Pv-pLDH test lines in P. falciparum samples incited to the present study, which assessed P. vivax-specific RDTs for the occurrence of false positive Pv-pLDH lines in P. falciparum samples. METHODS: Nine P. vivax-specific RDTs were tested with 85 P. falciparum samples of high (>/=2%) parasite density. Mixed P. falciparum/P. vivax infections were ruled out by real-time PCR. The RDTs included two-band (detecting Pv-pLDH), three-band (detecting P. falciparum-antigen and Pv-pLDH) and four-band RDTs (detecting P. falciparum, Pv-pLDH and pan-pLDH). RESULTS: False positive Pv-pLDH lines were observed in 6/9 RDTs (including two- three- and four-band RDTs). They occurred in the individual RDT brands at frequencies ranging from 8.2% to 29.1%. For 19/85 samples, at least two RDT brands generated a false positive Pv-pLDH line. Sixteen of 85 (18.8%) false positive lines were of medium or strong line intensity. There was no significant relation between false positive results and parasite density or geographic origin of the samples. CONCLUSION: False positive Pv-pLDH lines in P. falciparum samples with high parasite density occurred in 6/9 P. vivax-specific RDTs. This is of concern as P. falciparum and P. vivax are co-circulating in many regions. The diagnosis of life-threatening P. falciparum malaria may be missed (two-band Pv-pLDH RDT), or the patient may be treated incorrectly with primaquine (three- or four-band RDTs
Diagnostic accuracy of the Leishmania OligoC-TesT and NASBA-Oligochromatography for diagnosis of Leishmaniasis in Sudan
No full textBACKGROUND: The Leishmania OligoC-TesT and NASBA-Oligochromatography (OC) were recently developed for simplified and standardised molecular detection of Leishmania parasites in clinical specimens. We here present the phase II evaluation of both tests for diagnosis of visceral leishmaniasis (VL), cutaneous leishmaniasis (CL) and post kala-azar dermal leishmaniasis (PKDL) in Sudan. METHODOLOGY: The diagnostic accuracy of the tests was evaluated on 90 confirmed and 90 suspected VL cases, 7 confirmed and 8 suspected CL cases, 2 confirmed PKDL cases and 50 healthy endemic controls from Gedarif state and Khartoum state in Sudan. PRINCIPAL FINDINGS: The OligoC-TesT as well as the NASBA-OC showed a sensitivity of 96.8% (95% CI: 83.8%-99.4%) on lymph node aspirates and of 96.2% (95% CI: 89.4%-98.7%) on blood from the confirmed VL cases. The sensitivity on bone marrow was 96.9% (95% CI: 89.3%-99.1%) and 95.3% (95% CI: 87.1%-98.4%) for the OligoC-TesT and NASBA-OC, respectively. All confirmed CL and PKDL cases were positive with both tests. On the suspected VL cases, we observed a positive OligoC-TesT and NASBA-OC result in 37.1% (95% CI: 23.2%-53.7%) and 34.3% (95% CI: 20.8%-50.9%) on lymph, in 72.7% (95% CI: 55.8%-84.9%) and 63.6% (95% CI: 46.6%-77.8%) on bone marrow and in 76.9% (95% CI: 49.7%-91.8%) and 69.2% (95% CI: 42.4%-87.3%) on blood. Seven out of 8 CL suspected cases were positive with both tests. The specificity on the healthy endemic controls was 90% (95% CI: 78.6%-95.7%) for the OligoC-TesT and 100% (95% CI: 92.9%-100.0%) for the NASBA-OC test. CONCLUSIONS: Both tests showed high sensitivity on lymph, blood and tissue scrapings for diagnosis of VL, CL and PKDL in Sudan, but the specificity for clinical VL was significantly higher with NASBA-O
Family relationship, water contact and occurrence of Buruli ulcer in Benin
No full textBACKGROUND: Mycobacterium ulcerans disease (Buruli ulcer) is the most widespread mycobacterial disease in the world after leprosy and tuberculosis. How M. ulcerans is introduced into the skin of humans remains unclear, but it appears that individuals living in the same environment may have different susceptibilities. OBJECTIVES: This study aims to determine whether frequent contacts with natural water sources, family relationship or the practice of consanguineous marriages are associated with the occurrence of Buruli ulcer (BU). DESIGN: Case control study. SETTING: Department of Atlantique, Benin. SUBJECTS: BU-confirmed cases that were diagnosed and followed up at the BU detection and treatment center (CDTUB) of Allada (Department of the Atlantique, Benin) during the period from January 1st, 2006, to June 30th, 2008, with three matched controls (persons who had no signs or symptoms of active or inactive BU) for age, gender and village of residence per case. MAIN OUTCOMES MEASURED: Contact with natural water sources, BU history in the family and the practice of consanguineous marriages. RESULTS: A total of 416 participants were included in this study, including 104 cases and 312 controls. BU history in the family (p<0.001), adjusted by daily contact with a natural water source (p = 0.007), was significantly associated with higher odds of having BU (OR; 95% CI = 5.5; 3.0-10.0). The practice of consanguineous marriage was not associated with the occurrence of BU (p = 0.40). Mendelian disorders could explain this finding, which may influence individual susceptibility by impairing immunity. CONCLUSION: This study suggests that a combination of genetic factors and behavioral risk factors may increase the susceptibility for developing B
Modelling social reality: limitations to measuring the impact of HIV/AIDS on rural households
No full textDiagnostic accuracy and feasibility of serological tests on filter paper samples for outbreak detection of T.b. gambiense Human African Trypanosomiasis
No full textControl of human African trypanosomiasis (HAT) in the Democratic Republic of Congo is based on mass population screening by mobile teams; a costly and labor-intensive approach. We hypothesized that blood samples collected on filter paper by village health workers and processed in a central laboratory might be a cost-effective alternative. We estimated sensitivity and specificity of micro-card agglutination test for trypanosomiasis (micro-CATT) and enzyme-linked immunosorbent assay (ELISA)/T.b. gambiense on filter paper samples compared with parasitology-based case classification and used the results in a Monte Carlo simulation of a lot quality assurance sampling (LQAS) approach. Micro-CATT and ELISA/T.b. gambiense showed acceptable sensitivity (92.7% [95% CI 87.4-98.0%] and 82.2% [95% CI 75.3-90.4%]) and very high specificity (99.4% [95% CI 99.0-99.9%] and 99.8% [95% CI 99.5-100%]), respectively. Conditional on high sample size per lot (>/= 60%), both tests could reliably distinguish a 2% from a zero prevalence at village level. Alternatively, these tests could be used to identify individual HAT suspects for subsequent confirmatio
Heterogeneous and decreasing HIV prevalence among women seeking antenatal care in Kinshasa, Democratic Republic of Congo
No full textBACKGROUND: We examined HIV prevalence trends over 4.5 years among women receiving antenatal care in Kinshasa, Democratic Republic of Congo, by geographic location, clinic management and urbanicity. METHODS: Quarterly proportions and 95% confidence intervals (CIs) of pregnant women with HIV positive results were determined using aggregate service provision and uptake data from 22 maternity units that provided vertical HIV prevention services from October 2004 to March 2009. Assuming linearity, proportions were assessed for trend via the Cochran-Armitage test. Multivariable binomial regression was used to describe detailed prevalence trends. RESULTS: HIV testing was offered to 220 006 pregnant women; 210 348 (95.6%) agreed to be tested and 191 216 (90.9%) received their results. A total of 3999 women were found to be HIV positive, a prevalence of 1.90% (95% CI: 1.84-1.96%). The median quarterly proportion of women testing positive for HIV was 1.94% (range: 1.44-2.44%). Prevalence was heterogeneous in terms of maternity management, urbanicity and geographic location. Modeling suggested that the overall prevalence dropped from 2.04% (95% CI: 1.92-2.16%) to 1.77% (95% CI: 1.66-1.88%) over 4.5 years, a relative decrease of 13.2% (95% CI: 3.53-22.9%). Trend testing corroborated this decline (P < 0.01). CONCLUSIONS: The decreasing HIV prevalence among Kinshasa antenatal care seekers is robust and encouraging. The relatively low prevalence and the weak existing healthcare system require prevention of mother-to-child transmission interventions that strengthen maternal and child healthcare service delivery. Complacency would be unwarranted: assuming a uniform national crude birth rate of 50/1000 and 1.8% antenatal HIV prevalence, approximately 7000 pregnant HIV infected women in Kinshasa, and 60 000 nationwide, are in need of care and prevention services yearl