| Summary: | This study was carried out to investigate different aspects of the epidemiology of the
common intestinal protozoan infections in children in KwaZulu-Natal. The main aspects
studied were to:
i . monitor changes in the prevalence and intensity of the common intestinal
protozoons in children after receiving antihelmintic drugs,
ii. determine whether environmental and/or socio-economic factors are important in
the prevalence of the common intestinal protozoons,
iii. determine the occurrence of Cryptosporidium parvum in stool samples of
paediatric patients with gastroenteritis and in healthy school children.
Intestinal protowan species often co-occur with intestinal nematodes in infected
children and it is important to determine the effect that anti-nematode treatment has on
concomitant protozoan infections. The study included the analysis of stool samples by
the Formol-Ether Concentration Technique, exam ination of the obtained sediments for
intestinal helminths and protozoan species, and treatment of nematode-infected
individuals. Four surveys were carried out to determine the prevalence and intensity of
intestinal protozoons in school children before and after anthelmintic chemotherapy,
and the X(2) test was used to determine significant changes. Prevalences and intensities of
helminths were determined for significant changes after treatment using the Student's t-test.
Additional pre- and post-treatment prevalence data were obtained from four
schools in Health Region A of KwaZulu-Natal. The prevalence of Ascaris lumbricoides
decreased significantly from 75.2% to 9.7% after the first treatment, that of Trichuris
trichiura decreased from 77.7% to 62. 1%, and hookworm infections (presumably
Necator americanus) dropped fromI2.7% to 1.0% and remained very low for the rest of
the study. Very few individuals were infected with protozoan species and for statistical
analysis, these were combined. The prevalence of protozoan infections increased from
33.0% to 50.3% after the first treatment and from 35% to 42% after the second
treatment. The prevalence of A. lumbricoides decreased significantly again after the
second treatment while there was no significant decrease in the prevalence of T. trichiura. The intensities (number of eggs/gram of feaces) of the three nematodes also decreased
significantly after the two treatments. It is recommended that children who have been
treated for nematode infections should also be examined for protozoan infections, and
these should also be treated accordingly.
A retrospective analysis of protozoon prevalence data from different surveys in
KwaZulu-Natal was done in order to detennine the importance of environmental and/or
socio-economic factors in the distribution of intestinal protozoons. These data were
plotted on the map of KwaZulu-Natal using Geographic Information System (GIS).
Univariate analysis was carried out to determine significant correlations between the
prevalences of protozoan species and selected variables. The significant correlations
obtained were moderate and no strong correlations were obtained. Univariate stepwise
regression analysis was performed to determine the factors that combine best in
facilitating the transmission of protozoan species and significant associations were
obtained between the prevalence of protozoon species and a combination of
environmental and socio-economic factors. In most cases, the association between
prevalence and mid-summer temperature and rainfall were the most significant. This is
an indication of increased summer transmission. Altitude was significantly correlated
only with the prevalence of Endolimax nana. The fact that moderate correlations were
obtained between prevalence of intestinal protozoons and climatic and socio-economic
factors indicates that these factors are important in the distribution of the common
intestinal protozoons. However, lack of strong correlations suggests that in addition to
climatic and socio-economic factors, there are other factors that have an effect on the
distribution of intestinal protozoan species. In the multivariate analysis where the
variables were simultaneously considered, the presence of electricity was the only factor
that was significantly associated with the variation seen in the prevalence of intestinal
protozoons in the different study locations.
Cryplosporidium parvum is a parasitic protozoon that is associated with severe fatal
diarrhoea in children and immunocompromised individuals. Oocysts of this parasite
were found in 18.2% of stool samples collected from children (aged 6 to 48 months)
who were admitted in the paediatric wards at King Edward VIII Hospital, Durban. The stool samples were firstly concentrated using the Formal-ether method and the obtained
sediment was mixed with the Sheather's Sucrose solution and examined
microscopically. No oocysts were found in stool samples collected from older primary
school children. Although the diarrhoea in these children might have also been due to
other causes, the results obtained further show the importance of C. parvum as a cause
of diarrhoea in children below the age of five years. Knowledge of the epidemiology of
C. parvum is crucial in the control of this parasite as there is currently no effective
treatment. More intensive surveys are needed in detennining the epidemiology of this
pathogen in the South African population. === Thesis (M.Sc.)-University of Natal, Durban, 2001.
|
|---|
