Epidemiology and Molecular Characterization of Giardia Lamblia and Cryptosporidium Sp. Infections among Children In Accra, Ghana
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Date
2013-07
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University of Ghana
Abstract
Giardiasis and cryptosporidiosis remain as part of the commonest gastroenteritis in Ghana.
The diseases are caused by the protozoan parasites, Giardia lamblia and Cryptosporidium sp.
respectively. Inadequate supply of treated water and poor sanitation are some of the key
factors leading to the spread of these infections. Being zoonotic diseases, it is suspected that,
a large proportion of human infections could come from infected domestic and farm animals.
Though, use of molecular tools has helped to understand how the diseases spread in humans,
animals, and the environment, very little information is available on the epidemiology and
transmission routes of G. lamblia and Cryptosporidium sp. in Ghana, and a genetic
characterization of the parasite has also not been thoroughly investigated. Information on
clinical manifestations of Giardia infections and co-infections with other diarrhoeal causing
agents particularly rotavirus remain scanty. In the present study, the epidemiology and
molecular characterization of the two parasitic infections were investigated. The study, a
prospective cross-sectional hospital and community-based, was conducted in Accra, Ghana.
A total of 485 patients comprising of 365 diarrhoeic and 120 non-diarrhoeic children of age ≤
5 years, were studied. Stool samples were tested microscopically, and by enzyme
immunoassay kits. Positive samples were tested by the semi- nested polymerase chain
reaction (PCR) and subsequently characterized into genotypes by PCR-RFLP, and nucleotide
sequence analysis. Demographic and clinical data were obtained by a structured
questionnaire.
In the hospital-based study, prevalence rates of 5.8% and 22.0% were
observed for G. lamblia and Cryptosporidium sp. infections respectively, and prevalence in
diarrhoeic children was significantly higher than non-diarrhoeic children (P< 0.0001).
Infection in day care centres was 10.1% for G. lamblia and 4.2% for Cryptosporidium.
Neither gender nor breastfeeding habits, education level of mother, presence of domestic
animals, source of children’s food, seasons (dry or rainy) was a risk factor for infections of
the two parasites. However, age and source of drinking water were identified as associated
risk factors for infection. G. lamblia genotype B and Cryptosporidium parvum were
identified in the genotyping study. Although severity of rotaviral diarrhoea was reduced by
Giardia co-infection, the results cannot be conclusive. Although both parasites were present
in the studied population, cryptosporidial diarrhoea appears to be more common than giardial
diarrhoea. The presence of infections among non-diarrhoeal children is of much concern, as
they can spread infections unknowingly. The presence of genotype B as the only prevailing
genotype of G. lamblia indicates that infections from animals will be uncommon, but
Cryptosporidium parvum transmission could be either anthroponotic or zoonotic. The co-
infection study had a limitatio n, and therefore demands further investigation. Several
Cryptosporidium isolates that were successfully sequenced but whose identity were not clear,
need further investigation as they could be new species emerging.
Description
Thesis (PhD) - University of Ghana, 2013