6320 research outputs found
Sort by
Suppressed cellular alloimmune responses in HIV-exposed seronegative female sex workers
No full textParticular human leucocyte antigen (HLA) polymorphisms have been associated with a reduced risk of HIV transmission. However, protective alloimmune responses expected to result from such a genetic predisposition have not been demonstrated. To this end, we analysed and compared cellular and humoral alloimmune responses in a cohort of female sex workers who remained human immunodeficiency virus (HIV)-seronegative despite more than 3 years of high-risk sexual activity (ESN FSWs) with those of low-risk HIV-seronegative female blood donors in Abidjan, Côte d'Ivoire. ESN FSWs showed significantly lower allostimulated CD69 expression and secretion of interferon-gamma, macrophage inflammatory protein (MIP)-1beta and RANTES (regulated upon activation, normal T-cell expressed and secreted) by lymphocytes than controls. In contrast, ESN FSWs showed significantly higher mitogen-stimulated CD69 expression and secretion of tumour necrosis factor-alpha and MIP-1beta than controls. Suppression of cellular alloimmune responses among ESN FSWs was associated with a higher self-reported frequency of unprotected sex. Levels of anti-HLA class I alloantibodies in plasma were not significantly different between ESN FSWs and controls. These findings indicate that frequent sexual exposure to multiple partners results in suppression rather than activation of cellular alloimmune responses. Our data support the hypothesis that suppressed cellular alloimmune responses may play a role in protection against HIV infection
Implementation of rapid colorimetric methods for drug resistance detection in M. tuberculosis: perspectives for low-resource settings
No full text
CD4 T-cell count and HIV-1 infection in adults with uncomplicated malaria
No full textNot the final published versionBACKGROUND: HIV-1-negative children with malaria have reversible lymphocyte and CD4 count decreases. We assessed the impact of malaria parasitemia on the absolute CD4 count in both HIV-1-infected and non-HIV-infected adults. METHODS: In Ndola, Zambia, at the health-center level, we treated 327 nonpregnant adults for confirmed, uncomplicated, clinical malaria. We assessed HIV-1 status, CD4 count, and HIV-1 viral load (if HIV-1-infected) at enrollment and at 28 and 45 days after treatment. RESULTS: After successful antimalarial treatment, the median CD4 count at day 28 of follow-up increased from 468 to 811 cells/microL in HIV-1-negative and from 297 to 447 cells/microL in HIV-1-positive patients (paired t test, P < 0.001 for both). CD4 count increment was inversely correlated with CD4 count at day 0 in both HIV-1-negative (P < 0.001) and HIV-1-positive patients (P = 0.03). After successful treatment, the proportion of patients with CD4 count <200/microL at day 45 decreased from 9.6% to 0% in HIV-1-negative and from 28.7% to 13.2% in HIV-1-positive malaria patients (P < 0.001 for both). In patients with detectable but mostly asymptomatic parasitemia, CD4 count and, if HIV-1-infected, viral load at day 45 of follow-up were similar to those observed at enrollment. CONCLUSION: Interpretation of absolute CD4 count might be biased during or just after a clinical malaria episode. Therefore, in malaria-endemic areas, before taking any decision on the management of HIV-1-positive individuals, their malaria status should be assessed
Estimating disease prevalence in a Bayesian framework using probabilistic constraints
No full textStudies sometimes estimate the prevalence of a disease from the results of one or more diagnostic tests that are applied to individuals of unknown disease status. This approach invariably means that, in the absence of a gold standard and without external constraints, more parameters must be estimated than the data permit. Two assumptions are regularly made in the literature, namely that the test characteristics (sensitivity and specificity) are constant over populations and the tests are conditionally independent given the true disease status. These assumptions have been criticized recently as being unrealistic. Nevertheless, to estimate the prevalence, some restrictions on the parameter estimates need to be imposed. We consider 2 types of restrictions: deterministic and probabilistic restrictions, the latter arising in a Bayesian framework when expert knowledge is available. Furthermore, we consider 2 possible parameterizations allowing incorporation of these restrictions. The first is an extension of the approach of Gardner et al and Dendukuri and Joseph to more than 2 diagnostic tests and assuming conditional dependence. We argue that this system of equations is difficult to combine with expert opinions. The second approach, based on conditional probabilities, looks more promising, and we develop this approach in a Bayesian context. To evaluate the combination of data with the (deterministic and probabilistic) constraints, we apply the recently developed Deviance Information Criterion and effective number of parameters estimated (pD) together with an appropriate Bayesian P value. We illustrate our approach using data collected in a study on the prevalence of porcine cysticercosis with verification from external data
SSCP analysis of the P2 purine transporter TcoAT1 gene of Trypanosoma congolense leads to a simple PCR-RFLP test allowing the rapid identification of diminazene resistant stocks
No full textAnalyses were made on a Trypanosoma congolense contig coding a putative P2-like nucleoside transporter (the contig was named in this study TcoAT1). The sequence includes a start and stop codon and presents a high similarity with the gene TbAT1 of T. brucei (Smallest Sum Probability 2.8e-136). To investigate a possible link between point mutations and diminazene aceturate (DA) resistance in mice, the TcoAT1 putative genes of 26 T. congolense strains, characterised for DA sensitivity in the single dose mouse test, were screened by means of the Single Strand Conformation Polymorphism technique (SSCP). Results showed that the SSCP profiles of 23 out of 26 (88.5%) T. congolense strains were confirmed by the sensitivity test in mice with the commonly accepted criterion for sensitivity to diminazene being a CD80 of 20mg/kg in the mouse test. The remaining T. congolense strains showed a resistant SSCP profile and relapsed in mice after treatment at doses lower than 20mg/kg indicating that the SSCP is more sensitive than the single dose mouse test for the detection of resistance to diminazene. However, none of the strains used in this study showed a sensitive SSCP profile while they were resistant in the single dose mouse test. The sequencing of the TcoAT1 gene of two sensitive, two intermediate and two resistant strains allowed the set up of a PCR-RFLP test for the discrimination between sensitive and resistant strains confirming the SSCP results for the 26 strains of this study
Perception of cattle farmers of the efficacy of east coast fever immunization in Southern Zambia
No full textA study using a structured questionnaire was conducted to assess the perception of cattle farmers of the efficacy of East Coast fever (ECF) immunization in southern Zambia. One hundred and seventy-nine farmers from five districts in southern Zambia were interviewed. The majority of farmers (85%) perceived ECF immunization as being very effective and about half of them (51.4%) preferred immunization to other ECF control strategies. The study showed that the number of calves immunized was strongly associated with the farmer's perception of the benefits of immunization. There was no association between the number of calves immunized and the number of veterinary assistants in a given district or their transport situation. Overall mortality in ECF-immunized calves from various causes stood at 4.2%. Based on farmers' reports, the majority of these deaths seemed to have been caused by anaplasmosis, another tick-borne disease, and might have resulted from relaxation of tick control after ECF immunization. The reasons identified by farmers for not immunizing their animals included failure by immunizing teams to reach certain areas, not having calves of immunization age, and lack of money. These findings provide valuable information on how livestock farmers perceive and adopt new animal disease control strategies and the information could be useful in their planning and implementation