Patterns of Schistosoma haematobium infection, impact of praziquantel treatment and re-infection after treatment in a cohort of schoolchildren from rural KwaZulu-Natal/South Africa.
BACKGROUND
Schistosomiasis is one of the major health problems in tropical and sub-tropical countries, with school age children usually being the most affected group. In 1998 the Department of Health of the province of KwaZulu-Natal established a pilot programme for helminth control that aimed at regularly treating primary school children for schistosome and intestinal helminth infections. This article describes the baseline situation and the impact of treatment on S. haematobium infection in a cohort of schoolchildren attending grade 3 in a rural part of the province.


METHODS
Primary schoolchildren from Maputaland in northern KwaZulu-Natal were examined for Schistosoma haematobium infection, treated with praziquantel and re-examined four times over one year after treatment in order to assess the impact of treatment and patterns of infection and re-infection.


RESULTS
Praziquantel treatment was highly efficacious at three weeks after treatment when judged by egg reduction rate (95.3%) and cure rate of heavy infections (94.1%). The apparent overall cure rate three weeks after treatment (57.9%) was much lower but improved to 80.7% at 41 weeks after treatment. Re-infection with S. haematobium was low and appeared to be limited to the hot and rainy summer. Analysis of only one urine specimen per child considerably underestimated prevalence when compared to the analysis of two specimens, but both approaches provided similar estimates of the proportion of heavy infections and of average infection intensity in the population.


CONCLUSIONS
According to WHO guidelines the high prevalence and intensity of S. haematobium infection necessitate regular treatment of schoolchildren in the area. The seasonal transmission pattern together with the slow pace of re-infection suggest that one treatment per year, applied after the end of summer, is sufficient to keep S. haematobium infection in the area at low levels.
Saathoff
Elmar
E
Harvard School of Public Health, Department of Nutrition, 665 Huntington Avenue, Boston, MA 02115, USA. elmarsaathoff@compuserve.de
Olsen
Annette
A
Magnussen
Pascal
P
Kvalsvig
Jane D
JD
Becker
Wilhelm
W
Appleton
Chris C
CC
D000293:Adolescent; D017677:Age Distribution; D000871:Anthelmintics / Q000627:therapeutic use*; D002648:Child; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D010270:Parasite Egg Count / Q000379:methods; D010865:Pilot Projects; D011223:Praziquantel / Q000627:therapeutic use*; D015995:Prevalence; D012008:Recurrence; D012424:Rural Population; D012553:Schistosomiasis haematobia / Q000188:drug therapy* / Q000453:epidemiology*; D017678:Sex Distribution; D013019:South Africa / Q000453:epidemiology; D014556:Urine / Q000469:parasitology
D000871:Anthelmintics; D011223:Praziquantel