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.