Liposomal amphotericin B for complicated visceral leishmaniasis (kala-azar) in eastern Sudan: how effective is treatment for this neglected disease?

OBJECTIVES: The aim of this study was to report the patient profile and treatment outcomes, including relapses, of patients with visceral leishmaniasis (VL) treated with liposomal amphotericin B (AmBisome) in Gedaref, Sudan. METHODS: AmBisome was offered to two groups of patients: primary VL patients with specific criteria (age ≤2 or ≥45 years, advanced clinical disease, pregnancy, HIV co-infection and contraindications for antimonials) and VL relapses. AmBisome was given at a total dose of 30 mg/kg, over 10 days. Slow responders received up to 50 mg/kg. Treatment failure was confirmed parasitologically. Standardised treatment outcomes were assessed. RESULTS: Between March 2010 and June 2012, a total of 281 (74%) patients with primary VL and 98 (26%) patients with VL relapses received AmBisome (54% male, median age = 11 years, interquartile range 2-30). End-of-treatment outcomes for primary VL were 260 (92%) initial cure including three (1%) slow responders, three (1%) treatment failures, 14 (5%) deaths and four (1%) unknown outcomes. Outcomes for VL relapses were 92 (94%) initial cure with five (5%) slow responders, four (4%) treatment failures, one (1%) death and one (1%) unknown outcome. At 6 months, there were 19 (7%) relapses amongst primary VL and 10 (10%) VL relapses had a new relapse. Loss to follow-up in both groups was 38%. None of the deaths that occurred during the study period was attributed to AmBisome. CONCLUSION: AmBisome appears to be effective for initial cure of VL and the drug seems safe, but is expensive (400 USD/treatment). Sustained mechanisms to allow improved access of this expensive drug particularly in East Africa are urgently needed. Relapses and losses to follow-up require specific investigation.

Loss of balancing selection in the betaS globin locus.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Co-introgression of Y-chromosome haplogroups and the sickle cell gene across Africa's Sahel.

The Sahel that extends from the Atlantic Ocean to the Ethiopian highland is a historical reservoir of Africa's cultures and grandest populations and a known arena of ancient and recent migrations. We are interested in the issue whether such migrations were also carriers of genetic traits and whether this introgression could be associated with population genetic markers. Based on analysis of Y-chromosome haplogroups, we present evidence that the sickle gene, one of the major protective polymorphisms known in malaria, has in fact found its way only recently to the gene pool of the populations in eastern Sahel. We discuss the possible dynamics of the process and give estimates of the age of the introduction of the S allele into eastern Sahel.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. DISCUSSION AND CONCLUSION: Although these results do not provide evidence of causality, they provide useful suggestions for guiding further intervention studies on VL preventive measures.

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

BACKGROUND: 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. METHODS: Between the 5(th) of May and the 17(th) of June 2011, we conducted an exhaustive door-to-door survey in 45 villages of Al-Gureisha locality. Deaths were investigated by verbal autopsies. All individuals with (i) fever of at least two weeks, (ii) VL diagnosed and treated in the previous year, and (iii) clinical suspicion of post-kala-azar dermal leishmaniasis (PKDL) were referred to medical teams for case ascertainment. A new case of VL was a clinical suspect with a positive rk39 rapid test or direct agglutination test (DAT). RESULTS: In the 45 villages screened, 17,702 households were interviewed, for a population of 94,369 inhabitants. The crude mortality rate over the mean recall period of 409 days was 0.13/10'000 people per day. VL was a possible or probable cause for 19% of all deaths. The VL-specific mortality rate was estimated at 0.9/1000 per year. The medical teams examined 551 individuals referred for a history of fever of at least two weeks. Out of these, 16 were diagnosed with primary VL. The overall incidence of VL over the past year was 7.0/1000 persons per year, or 7.9/1000 per year when deaths possibly or probably due to VL were included. Overall, 12.5% (11,943/95,609) of the population reported a past VL treatment episode. DISCUSSION AND CONCLUSION: VL represents a significant health burden in eastern Gedaref State. Active VL case detection had a very low yield in this specific setting with adequate access to care and may not be the priority intervention to enhance control in similar contexts.