Burden of visceral leishmaniasis in villages of eastern gedaref state, Sudan: an exhaustive cross-sectional survey.

Since December 2009, Médecins Sans Frontières has diagnosed and treated patients with visceral leishmaniasis (VL) in Tabarak Allah Hospital, eastern Gedaref State, one of the main endemic foci of VL in Sudan. A survey was conducted to estimate the VL incidence in villages around Tabarak Allah

Loss of balancing selection in the βS globin locus

<p>Abstract</p> <p>Background</p> <p>Probably the best example of the rise and maintenance of balancing selection as an evolutionary trend is the role of S-haemoglobin (HbS - rs334) in protecting from malaria. Yet, the dynamics of such a process remains poorly understood, particularly in relation to different malaria transmission rates and the genetic background of the affected populations.</p> <p>Methods</p> <p>We investigated the association of haemoglobin HbS in protection from clinical episodes of malaria in two populations/villages where malaria is endemic, but mostly presenting in mild clinical forms. Five-hundred and forty-six individuals comprising 65 and 82 families from the Hausa and Massalit villages respectively were genotyped for HbS. Allele and genotype frequencies as well as departure from Hardy-Weinberg Equilibrium were estimated from four-hundred and seventy independent genotypes across different age groups. Age-group frequencies were used to calculate the coefficient-of-fitness and to simulate the expected frequencies in future generations.</p> <p>Results</p> <p>Genotype frequencies were within Hardy-Weinberg expectations in Hausa and Massalit in the total sample set but not within the different age groups. There was a trend for a decrease of the HbS allele frequency in Hausa and an increase of frequency in Massalit. Although the HbS allele was able to confer significant protection from the clinical episodes of malaria in the two populations, as suggested by the odds ratios, the overall relative fitness of the HbS allele seems to have declined in Hausa.</p> <p>Conclusions</p> <p>Such loss of balancing selection could be due to a combined effect of preponderance of non-clinical malaria in Hausa, and the deleterious effect of the homozygous HbS under circumstances of endogamy.</p

Determinants of Visceral Leishmaniasis: A Case-Control Study in Gedaref State, Sudan

<div><p>Background</p><p>Improving knowledge on local determinants of visceral leishmaniasis (VL) is crucial to guide the development of relevant control strategies. This study aimed to identify individual and household level determinants of primary VL in 24 highly endemic villages of Tabarak Allah hospital’s catchment area, Gedaref State, Sudan.</p><p>Methods</p><p>From September 2012 to July 2013, in an unmatched case-control design, 198 patients with primary VL were compared to 801 controls free of VL symptoms and with a negative VL rapid test. Using random spatial sampling, controls were selected with a distribution of age, sex and village of residence proportionate to the distribution of the target population. Data were collected using a structured questionnaire.</p><p>Results</p><p>Children and men were at higher risk of VL. Reporting VL patient(s) in the household in the previous year was the strongest VL risk factor. In a multivariate analysis, VL risk increased with household size, sleep location (outside the yard, not in the farm), evening outdoor activities in the rainy season (playing, watching TV, radio listening), use of ground nut oil as animal repellent and of smoke of Acacia seyal as indoor repellent, presence of dogs in the yard at night, Acacia nilotica in the yard’s immediate surroundings and of a forest at eye range. VL risk appeared to decrease with the use of drinking water sources other than the village water tank, a buffer distance from the adjacent house yard, and with the presence of animals other than dogs in the yard at night. In contrast with previous studies, housing factors, mosquito-net use, black cotton soil, ethnicity, socioeconomic index, presence of Balanites aegyptica and Azadirachta indica in the yard were not independent VL determinants.</p><p>Discussion and conclusion</p><p>Although these results do not provide evidence of causality, they provide useful suggestions for guiding further intervention studies on VL preventive measures.</p></div

Study area, case-control study on determinants of visceral leishmaniasis, Gedaref State, Sudan, 2012–2013.

<p>Left map: Annual incidence of visceral leishmaniasis (VL) in Sudan (2011) from < 5 cases /100,000 inhabitants (yellow) to ≥ 15 cases /100,000 inhabitants (red) (Source: Annual Report, Federal Ministry of Health, Sudan). Right map: Annual incidence of VL in Sudan (2011) proportionate to the size and colour of the circles (from 0 to ≥ 20 cases /1,000 inhabitants). The black circle includes the 24 study villages.</p

Socio-demographic characteristics, case-control study on determinants of visceral leishmaniasis, Gedaref State, Sudan, 2012–2013.

<p>Socio-demographic characteristics, case-control study on determinants of visceral leishmaniasis, Gedaref State, Sudan, 2012–2013.</p

Individual level determinants associated (p<0.20) with VL after adjustment: crude and adjusted analysis.

<p>LR: Likelihood ratio; VL: visceral leishmaniasis; OR: Odds Ratio; 95%CI: 95% Confidence Interval;</p><p>* Adjusted for age, sex, their interaction, and village as random effect;</p><p>**Housework, too young, attending school, unemployed.</p><p>*** In the rainy season as a proxy of the whole year (trend of association being similar in both seasons though some factors less frequent in the dry season).</p><p>Gedaref State, Sudan, 2012–2013.</p