The epidemiology of human hookworm infections in the southern region of Mali

Two surveys of hookworm (Necator americanus) infections, conducted three ye ars apart (December 1994 and January 1998) in a village in the Sikasso regi on of Mall, revealed that overall prevalence of infection was 68.7% and 53% , respectively. In both years there was a highly significant difference bet ween the sexes in the prevalence and abundance of infection, with male subj ects carrying heavier infections than females. Both prevalence and abundanc e of infection increased with age, although in 1998 there was a strong inte raction between sex and age, arising from the declining egg counts among 16 -20-year-old females and the continuing increase among males, reinforced by the subsequent reduction among the older males (greater than or equal to 6 1 years) and concomitant increase among females. After controlling for the effects of age, sex and their interaction, a highly significant positive re lationship was detected between faecal egg counts of individuals who were e xamined in both 1994 and 1998 (n = 134), indicating predisposition to infec tion. This relationship remained significant in each of 4 age classes spann ing 7-79 years. The members of some family compounds were shown to carry he avier infections than expected whilst others were less infected, suggesting compound-related clustering of hookworm infections. The use of footwear in creased with age but there was no significant relationship between the exte nt of use of footwear and the abundance of hookworm infection. Eyesight det eriorated with age and impaired vision was particularly prominent among the older sectors of the community, a legacy from the time when onchocerciasis was widely prevalent in the region, Although men with partially damaged ey es carried lower infections than expected for their age, no overall signifi cant relationship was found between quality of Vision and hookworm infectio ns. These results are discussed in relation to hookworm epidemiology in gen eral and in Mali in particular.