Susceptibility to intestinal infection and diarrhoea in Zambian adults in relation to HIV status and CD4 count.
BACKGROUND
The HIV epidemic in sub-Saharan Africa has had a major impact on infectious disease, and there is currently great interest in the impact of HIV on intestinal barrier function. A three year longitudinal cohort study in a shanty compound in Lusaka, Zambia, carried out before anti-retroviral therapy was widely available, was used to assess the impact of HIV on susceptibility to intestinal infectious disease. We measured the incidence and seasonality of intestinal infection and diarrhoea, aggregation of disease in susceptible individuals, clustering by co-habitation and genetic relatedness, and the disease-to-infection ratio.


METHODS
Adults living in a small section of Misisi, Lusaka, were interviewed every two weeks to ascertain the incidence of diarrhoea. Monthly stool samples were analysed for selected pathogens. HIV status and CD4 count were determined annually.


RESULTS
HIV seroprevalence was 31% and the prevalence of immunosuppression (CD4 count 200 cells/microL or less) was 10%. Diarrhoea incidence was 1.1 episodes per year and the Incidence Rate Ratio for HIV infection was 2.4 (95%CI 1.7-3.3; p < 0.001). The disease-to-infection ratio was increased at all stages of HIV infection. Aggregation of diarrhoea in susceptible individuals was observed irrespective of immunosuppression, but there was little evidence of clustering by co-habitation or genetic relatedness. There was no evidence of aggregation of asymptomatic infections.


CONCLUSIONS
HIV has an impact on intestinal infection at all stages, with an increased disease-to-infection ratio. The aggregation of disease in susceptible individuals irrespective of CD4 count suggests that this phenomenon is not a function of cell mediated immunity.
Kelly
Paul
P
Tropical Gastroenterology & Nutrition group, Department of Medicine, University of Zambia School of Medicine, Lusaka, Zambia. guts@coppernet.zm
Todd
Jim
J
Sianongo
Sandie
S
Mwansa
James
J
Sinsungwe
Henry
H
Katubulushi
Max
M
Farthing
Michael J
MJ
Feldman
Roger A
RA
D000293:Adolescent; D000328:Adult; D000368:Aged; D018791:CD4 Lymphocyte Count; D015331:Cohort Studies; D004198:Disease Susceptibility; D004403:Dysentery / Q000453:epidemiology* / Q000276:immunology / Q000821:virology; D005260:Female; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D016867:Immunocompromised Host; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012621:Seasons; D055815:Young Adult; D015024:Zambia