Epidemiology of visceral leishmaniasis in Atbara River area, eastern Sudan: the outbreak of Barbar El Fugara village (1996-1997).
An outbreak of visceral leishmaniasis (VL) started in 1995 in the Atbara River area in eastern Sudan. This article reports on this outbreak and on the clinical and immunological studies that were carried out in a village, with the highest incidence of VL cases, from 1996 to 1997. A significant increase in VL incidence was recorded in a dozen villages in this area; one village, Barbar El Fugara accounted for half of the total number of cases recorded at the regional hospital. A total of 152 VL and 61 post kala-azar dermal lesion (PKDL) cases were diagnosed and treated in Barbar. Household (n = 671) and school (n = 276) surveys were performed using the leishmanin skin test (LST) and the direct agglutination test (DAT). LST positivity was 23.1 and 15.7%, whereas DAT positivity was 8.9 and 26.4% in both surveys, respectively. No gender differences were observed in either test. Unlike DAT, LST positivity was predominant in the higher age groups that also exhibited lower prevalence of VL. Few individuals were positive by both tests (1.3%, 5.2%) while the majority (68.8%, 64.8%) had no evidence of acquired immune response, suggesting either a role of innate immunity in preventing parasite establishment or, unexpectedly, lack of exposure to Leishmania. Subclinical parasitism was also demonstrated, as evidence of both acquired humoral and cellular immune responses was observed in individuals with no past history of the disease. The wide spectrum of L. donovani/human interactions may be explained by differential exposure to environmental risk factors, parasite strain polymorphisms or host genetic makeup.
EL-Safi
Sayda Hassan
SH
Department of Microbiology and Parasitology, Faculty of Medicine, University of Khartoum, PO Box 102, Khartoum, Sudan.
Bucheton
Bruno
B
Kheir
Musa Mohamed
MM
Musa
Hassan Abdel Aziz
HA
EL-Obaid
Moawia
M
Hammad
Awad
A
Dessein
Alain
A
D000328:Adult; D000368:Aged; D000372:Agglutination Tests / Q000379:methods / Q000706:statistics & numerical data; D000818:Animals; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D007407:Interviews as Topic; D007898:Leishmaniasis, Visceral / Q000097:blood / Q000175:diagnosis / Q000453:epidemiology*; D008297:Male; D008499:Medical Records; D008875:Middle Aged; D011159:Population Surveillance; D015995:Prevalence; D012882:Skin Tests / Q000379:methods / Q000706:statistics & numerical data; D013397:Sudan / Q000453:epidemiology