The effects of physical and chemical factors on the development of eggs of Ascaris lumbricoides and Trichuris trichiura
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Date
1991Author
Odera, Elizabeth I
Type
ThesisLanguage
enMetadata
Show full item recordAbstract
The study was done in the Parasitology Laboratory at the
Department of Medical Microbiology of the University of Nairobi.
It was an invitro experimental study. Also the development of
eggs (segmentation and embryonation) in the external soil
environment and their occurrence in a natural peridomestic urban
environment were studied. The objective was to study the effects
of various physical and chemical factors on the development of
eggs of Ascaris lumbrocides and Trichuris trichiura.
Positive stool specimens for eggs of Ascaris lumbrocides
and/or Trichuris trichiura were identified from the collected and
examined stool specimens of the patients at the Kenyatta National
Hospital. Also soil specimens were collected and examined for
similar eggs from two underprivileged areas in Nairobi. stool
specimens were re-examined and confirmed microscopically using
the formal-ether concentration (FEC) method by the Principal
investigator and a senior laboratory technologist. The positives
were pooled together and analyzed in bulk.
also included.
Control samples were
The experiments done included the incubation of the stool
samples in different physical and chemical conditions such as
temperature, humidity, acidity and alkalinity. Samples were
incubated for a duration of five weeks. They were examined
weekly for egg development. These were then counted and recorded
~developed, segmented or embryonated.
As described in the results, Ascaris lumbricoides eggs were
majority and Trichuris trichiura eggs were few. The results
how that for the temperatures (22 to 28uc) studied, development
eggs was best at 28JC, less well at 37°C and not at
The eggs developed at room temperature better than
37~ under similar conditions. The eggs developed better in
acidic conditions compared to alkaline ones.
The eggs developed in both 4% and 10% formalin solutions but
better in the former solution. The eggs developed in conditions
of adequate moisture but not in those without moisture. In
general, development of eggs was better aerobically than
anaerobically except in 10% formalin solution.
In most of the experiments, the proportion of eggs developed
was highest at week three and thereafter declined in weeks 4 and
5.This was more evident under alkaline conditions and at 37cC.
The results of egg development in the external soil
environment showed that about one sixth of the eggs developed.The
eggs seen and identified from examination of soil collected in
the urban periaomestic environment were of Ascaris lumbricoides
and few of them were segmented or embryonated.
Citation
Odera, E.I(1991). The effects of physical and chemical factors on the development of eggs of Ascaris lumbricoides and Trichuris trichiuraPublisher
College of Health Sciences, University of Nairobi
Description
Master of Medicine thesis