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J Parasit Dis Diagn Ther 2017 | Volume 2 Issue 4
allied
academies
International Conference on
Zoology, Microbiology & Medical Parasitology
October 30-November 01, 2017 | Chicago, USA
Schistosomiasis is a parasitic disease of major public health
importance in many countries in Africa, Asia, and South
America. The disease is caused by trematodes of the genus
Schistosoma that require specific freshwater snail species to
complete their life cycles. Prior to 1985, the openwaters of Lake
Malaŵi were free from schistosome transmission. Over the past
decades, however, the prevalence of urinary schistosomiasis
has increased dramatically in the southern part of the lake.
We found the prevalence of human schistosomiasis in school-
aged children to be negatively correlated with the density of
molluscivorous fishes. Specifically, the increase in infection rate
in southern Lake Malawi between 1978 and 1991 is coincident
with the reduction in numbers of snail-eating fishes. During
2003, we determined the relative abundance of molluscivorous
fishes and snail density at 18 sites throughout the lake, and
schistosome infection in school-aged children living in selected
lake shore communities of LakeMalaŵi. At the 18 sites sampled
in 2003, we found that snail abundance decreased with an
increase in abundance of snail-eating fishes. Furthermore,
the 2003 samples showed that the abundance of snail-eating
fishes increased and there was a reduction in schistosomiasis
in school-aged children in Chembe Village. We believe that
we will not observe a return to the 1978 infection rates until
these fishes continue to increase and inhabit shallower waters.
The transmission of the disease may be further complicated.
We postulated that a strain of S. haematobium from other
parts of Africa, which was introduced into the Cape Maclear
region of Lake Malaŵi by tourists, was compatible with Bulinus
nyassanus—which is a close relative of B. truncatus, and
interbred with the indigenous strain of S. haematobium, which
ultimately produced via introgression a strain that can use
both B. globosus and B. nyassanus as intermediate hosts. This
actively evolving situation involving intermediate snail–host
switching and decline of Trematocranus placodon, a natural
cichlid snail predator, will impact on transmission of urogenital
schistosomiasis within the local communities and on tourists
who visit Lake Malaŵi.
Speaker Biography
Jay R Stauffer is a Distinguished Professor of Ichthyology at Penn State University. His
international work has involved the transfer of research results and technology to both
the local governments and the people of Malawi. The Smithosonian (1988:144-155)
highlighted his early work on Lake Malaŵi and the British Broadcasting Corporation
(BBC) used him as a primary consultant on fishes and used his underwater videos
in several of their productions, including Blue Planet In 2006, he co-authored an
educational brochure entitled Bilharzia in Lake Malaŵi – What are the Facts , that was
published in both English and Chechewa, the most widely used language in Malaŵi
). HIs
international studies also gave him the opportunity to describe several species of fishes
from Malaŵi and Nicaragua, and to study the adverse impact of the introduction of
African tilapia on native species.
e:
Jay R Stauffer
Penn State University, USA
Controlling vectors and hosts of Schistosomes in Lake Malawi