A major advance in our understanding of the natural history
of
Schistosoma haematobium
-related morbidity has come through the introduction of the portable ultrasound
machines for non-invasive examination of the kidneys and bladder. With the
use of generators or battery packs to supply power in non-clinical field
settings, and with the use of instant photography or miniaturized thermal
printers to record permanent images, it is possible to examine scores of
individuals in endemic communities every day. Broad-based ultrasound screening
has allowed better definition of age-specific disease risks in urinary schistosomiasis.
Results indicate that urinary tract abnormalities are common (18% overall
prevalence) in S. haematobium transmission areas, with a 2-4% risk of either
severe bladder abnormality or advanced ureteral obstruction. In longitudinal
surveys, ultrasound studies have shown that praziquantel and metrifonate
therapy are rapidly effective in reversing urinary tract abnormalities among
children. The benefits of treating adults are less well known, but research
in progress should help to define this issue. Similarly, the prognosis of
specific ultrasound findings needs to be clarified, and the ease of sonographic
examination will make such long-term follow-up studies feasible. In summary,
the painless, quick, and reproducible ultrasound examination has become
an essential tool in the study of urinary schistosomiasis.