Abstract:
Infections with malaria parasites, schistosomes and soil-transmitted helminths are
widespread in sub-Saharan Africa and pose an enormous challenge on the socio-economic
development of the region. Polyparasitism involving malaria and helminth infections is
common and often associated with severe morbidities and mortalities. Co-infections of
malaria, schistosomiasis and soil-transmitted helminth exist in parts of Tanzania, however,
very little is known about their prevalence. A cross-sectional survey was conducted in the
Nyamatongo ward of northwest Tanzania near Lake Victoria and a total of 400 primary
school children from four schools were examined for Plasmodium falciparum, the malaria
parasite, Schistosoma mansoni, the bilharzia parasite and soil-transmitted helminths. Stool
specimens obtained from the children were processed on microscope glass slides using the
Kato-Katz method and were examined for helminth eggs under a compound microscope.
Giemsa-stained thick and thin blood smears were also prepared from finger prick blood
samples and examined under a microscope for malaria parasites. Hemoglobin levels were
determined from the finger prick blood samples using the Hemocue system (HemoCue AB,
Ängelholm, Sweden) and organomegaly (liver and spleen enlargement) was determined by
clinical examination of the study subjects.
Prevalence of P. falciparum was 13.5% (95%CI, 10.2-16.8) while S. mansoni was 64.3%
(95%CI, 59.6-68.9). The soil-transmitted helminths present in the study children were
hookworms with a prevalence of 38% (95%CI, 33.2-42.8). Apparently, A. lumbricoides
and T. trichiura were absent. About 26.5% (95%CI, 21.9-30.6) of the children examined
harbored two (2) parasite species with S. mansoni and hookworm co-infections being the
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most common at 69% (95%CI, 60.2-77.8) followed by S. mansoni -P. falciparum coinfections at 22.6% (95%CI, 14.7-30.5), and hookworm - P. falciparum co-infections at
5.7% (95%CI, 1.3-10.1). The prevalence of co-infection of P. falciparum, S. mansoni and
hookworm was 2.8% (95%CI, 1.15-4.4). The overall prevalence of co-infections with these
parasites was 29.3%.
Prevalence of anaemia (<11g/dL) was 20% (95%CI, 15.9-23.7) and about 61% (95%CI,
50.2-71.8) of the anaemic children were infected with one or more of the parasites in the
present study. Prevalence of hepatomegaly, splenomegaly or hepatosplenomegaly were
22% (95%CI, 17.9-26.1), 11.5% (8.4-14.6) and 7.5% (95%CI, 4.9-10.1) respectively.
About 41% (95%CI, 31.6-50.4) of the children with organomegaly were infected with one
or more parasite species in the study.
In conclusion, the findings of this study suggest that S. mansoni, hookworm and P.
falciparum are prevalent among the school children in the study area and co-infections are
common. The findings support the need for initiatives to implement a new framework for
an integrated approach in disease management. Longitudinal studies which will clearly
identify the associations between parasites and associated morbidities are required.