The results embodied in the following report were
obtained in the course of a general helminthological
survey of Southern Rhodesia during the year 1930. The
work was undertaken on behalf of the London School of
Hygiene and Tropical Medicine which, in conjunction with
the Government of Southern Rhodesia, has established a
Rhodesian Research Fellowship for the purpose of
facilitating the investigation of disease conditions in
the Colony. The present investigation was begun in May
1930 and continued until February 1931.
When the work commenced schistosome infestations
were known to be present both in the Europeans and the
Natives of the Colony. From the clinical standpoint,
however, the disease was regarded as relatively
unimportant as the gross manifestations of the disease,
either in its urinary or intestinal form were rarely
Precise knowledge was lacking on the intermediate
molluscan hosts of the schistosome species met with in
Rhodesia. Various fresh -water molluscs had, from time
to time, been submitted to the Public Health Laboratory,
Salisbury, but no animal experimentation had been carried
out to determine the nature of the cercariae they
chanced to harbour.
The possibility of the existence of reservoir
hosts for mammalian schistosomes capable of parasitising
man had not been investigated.
In the course of a few preliminary examinations
it soon became apparent that schistosome infestations
were much more prevalent amongst the Native population
than had been hitherto suspected and on this account it
was decided to devote as much of the available time as
possible to a study of the schistosome problem.
While determining the incidence of the
infestation amongst the Natives of the different regions
of Southern Rhodesia, every opportunity was taken to
investigate the bionomics of those fresh -water molluscs
which constituted the intermediate hosts of the
parasites. At the same time frequent autopsies were
carried out on various mammals, such as monkeys, baboons,
sheep, etc., for the purpose of detecting previously
unsuspected hosts for the human schistosomes.