Prevalence of pulmonary tuberculosis and HIV infections and risk factors associated to tuberculosis in detained persons in Antananarivo, Madagascar.

The incidence rate of tuberculosis in prisons is estimated to be 8 times greater than that in the general population in Madagascar. Our objectives were to estimate the prevalence of pulmonary tuberculosis and HIV infection among prisoners and to identify risk factors associated with tuberculosis. We conducted a cross-sectional study at the central prison of Antananarivo from March to July 2021. Individual male and female inmates aged ≥ 13 years who had lived in the prison for at least three months prior to the study period were included as participants. Acid-fast bacilli detection by microscopy and/or culture, an intradermal tuberculin test, a chest X-ray, and a rapid diagnostic orientation test for HIV were performed. Among 748 participants, 4 (0.5%) were confirmed to have pulmonary tuberculosis. Overall, 14 (1.9%) patients had "confirmed" or "probable" tuberculosis [0.90-2.84, 95% CI]. The proportion of participants with latent tuberculosis infection was 69.6% (517/743) based on a positive tuberculin test without clinical symptoms or radiography images indicating tuberculosis. Out of 745 HIV screening tests, three showed reactive results (0.4%). Age (OR = 4.4, 95% CI [1.4-14.0]) and prior tuberculosis treatment (or episodes) were found to be associated with confirmed and probable tuberculosis.

Geographical and environmental approaches to urban malaria in Antananarivo (Madagascar).

BACKGROUND: Previous studies, conducted in the urban of Antananarivo, showed low rate of confirmed malaria cases. We used a geographical and environmental approach to investigate the contribution of environmental factors to urban malaria in Antananarivo. METHODS: Remote sensing data were used to locate rice fields, which were considered to be the principal mosquito breeding sites. We carried out supervised classification by the maximum likelihood method. Entomological study allowed vector species determination from collected larval and adult mosquitoes. Mosquito infectivity was studied, to assess the risk of transmission, and the type of mosquito breeding site was determined. Epidemiological data were collected from November 2006 to December 2007, from public health centres, to determine malaria incidence. Polymerase chain reaction was carried out on dried blood spots from patients, to detect cases of malaria. Rapid diagnostic tests were used to confirm malaria cases among febrile school children in a school survey.A geographical information system was constructed for data integration. Altitude, temperature, rainfall, population density and rice field surface area were analysed and the effects of these factors on the occurrence of confirmed malaria cases were studied. RESULTS: Polymerase chain reaction confirmed malaria in 5.1% of the presumed cases. Entomological studies showed An. arabiensis as potential vector. Rice fields remained to be the principal breeding sites. Travel report was considered as related to the occurrence of P. falciparum malaria cases. CONCLUSION: Geographical and environmental factors did not show direct relationship with malaria incidence but they seem ensuring suitability of vector development. Absence of relationship may be due to a lack of statistical power. Despite the presence of An. arabiensis, scarce parasitic reservoir and rapid access to health care do not constitute optimal conditions to a threatening malaria transmission. However, imported malaria case is suggestive to sustain the pocket transmission in Antananarivo.

Bayesian mapping of pulmonary tuberculosis in Antananarivo, Madagascar.

BACKGROUND: Tuberculosis (TB), an infectious disease caused by the Mycobacterium tuberculosis is endemic in Madagascar. The capital, Antananarivo is the most seriously affected area. TB had a non-random spatial distribution in this setting, with clustering in the poorer areas. The aim of this study was to explore this pattern further by a Bayesian approach, and to measure the associations between the spatial variation of TB risk and national control program indicators for all neighbourhoods. METHODS: Combination of a Bayesian approach and a generalized linear mixed model (GLMM) was developed to produce smooth risk maps of TB and to model relationships between TB new cases and national TB control program indicators. The TB new cases were collected from records of the 16 Tuberculosis Diagnostic and Treatment Centres (DTC) of the city from 2004 to 2006. And five TB indicators were considered in the analysis: number of cases undergoing retreatment, number of patients with treatment failure and those suffering relapse after the completion of treatment, number of households with more than one case, number of patients lost to follow-up, and proximity to a DTC. RESULTS: In Antananarivo, 43.23% of the neighbourhoods had a standardized incidence ratio (SIR) above 1, of which 19.28% with a TB risk significantly higher than the average. Identified high TB risk areas were clustered and the distribution of TB was found to be associated mainly with the number of patients lost to follow-up (SIR: 1.10, CI 95%: 1.02-1.19) and the number of households with more than one case (SIR: 1.13, CI 95%: 1.03-1.24). CONCLUSION: The spatial pattern of TB in Antananarivo and the contribution of national control program indicators to this pattern highlight the importance of the data recorded in the TB registry and the use of spatial approaches for assessing the epidemiological situation for TB. Including these variables into the model increases the reproducibility, as these data are already available for individual DTCs. These findings may also be useful for guiding decisions related to disease control strategies.

Determining areas that require indoor insecticide spraying using Multi Criteria Evaluation, a decision-support tool for malaria vector control programmes in the Central Highlands of Madagascar.

BACKGROUND: The highlands of Madagascar present an unstable transmission pattern of malaria. The population has no immunity, and the central highlands have been the sites of epidemics with particularly high fatality. The most recent epidemic occurred in the 1980s, and caused about 30,000 deaths. The fight against malaria epidemics in the highlands has been based on indoor insecticide spraying to control malaria vectors. Any preventive programme involving generalised cover in the highlands will require very substantial logistical support. We used multicriteria evaluation, by the method of weighted linear combination, as basis for improved targeting of actions by determining priority zones for intervention. RESULTS: Image analysis and field validation showed the accuracy of mapping rice fields to be between 82.3% and 100%, and the Kappa coefficient was 0.86 to 0.99.A significant positive correlation was observed between the abundance of the vector Anopheles funestus and temperature; the correlation coefficient was 0.599 (p < 0.001). A significant negative correlation was observed between vector abundance and human population density: the correlation coefficient was -0.551 (p < 0.003). Factor weights were determined by pair-wise comparison and the consistency ratio was 0.04. Risk maps of the six study zones were obtained according to a gradient of risk. Nine of thirteen results of alert confirmed by the Epidemiological Surveillance Post were in concordance with the risk map. CONCLUSION: This study is particularly valuable for the management of vector control programmes, and particularly the reduction of the vector population with a view to preventing disease. The risk map obtained can be used to identify priority zones for the management of resources, and also help avoid systematic and generalised spraying throughout the highlands: such spraying is particularly difficult and expensive. The accuracy of the mapping, both as concerns time and space, is dependent on the availability of data. Continuous monitoring of malaria transmission factors must be undertaken to detect any changes. A regular case notification allows risk map to be verified. These actions should therefore be implemented so that risk maps can be satisfactorily assessed.

Susceptibility of Plasmodium falciparum to the drugs used to treat severe malaria (quinine) and to prevent malaria (mefloquine, cycloguanil) in Comoros Union and Madagascar.

OBJECTIVES: To monitor the sensitivity of Plasmodium falciparum to the drugs used to treat severe malaria and to prevent malaria in Comoros and Madagascar. DESIGN: We used the in vitro isotopic method to test the sensitivity of P. falciparum to quinine, mefloquine and cycloguanil. RESULTS: We tested fresh isolates of P. falciparum, collected from patients living in urban, suburban and rural areas and suffering from uncomplicated malaria in 2001, against at least one of the antimalarials cited above. In both countries all of the successfully tested isolates were sensitive to quinine (N = 243) and to cycloguanil (N = 67). The mean IC50 ranged from 85.7 to 133.7 nM for quinine. For cycloguanil, the mean IC50 ranged from 1.4 to 20.2 nM and the highest IC50 value (102.5 nM) was recorded in Comoros. Only 0.9% (1/110) of the informative isolates from Madagascar were mefloquine-resistant (0/18 in Comoros). The mefloquine mean IC50s were 8.2 nM, 14.1 nM and 11.6 nM respectively in the rural, suburban and urban areas of Madagascar, and 5.9 nM in Comoros. A positive correlation was found between quinine and mefloquine IC50s (N = 127, r = 0.48, p < 10(-6)), but in vitro mefloquine was 6-16 times more potent than quinine. No correlation was noticed between the activities of quinine and cycloguanil or between the activities of mefloquine and cycloguanil. CONCLUSION: We therefore advocate the use of a full-course regimen of quinine, as recommended by the World Health Organisation (WHO), to treat above all severe malaria in Madagascar and Comoros. Our results also demonstrate that the use of mefloquine- and cycloguanil-based antimalarials is still justified to prevent malaria in both countries, mainly in the case of travellers.