II.2.3. Prevalence of
gastrointestinal infections in Rwanda
A Survey done in 2008 on 8313 children from 30 districts by
TRAC PLUS on helminthes infections have identified six species of intestinal
helminthes with an overall prevalence of 65.8% for soil-transmitted helminthes
(STH) infections. The predominant parasite was Ascaris lumblicoides
which was observed in 38.6% of the children, followed by hookworms in 31.6%,
Trichuris trichiura in 27.0%, and Schistosoma mansoni in 2.7%
of the children. Overall, the prevalence per district varied from 0% to 69.5%
(TRAC PLUS, 2008). Others researches conducted by KIE students in Rwanda shown
that protozoa affecting children were Entamoeba histolytica, G.
lamblia, and T. intestinalis. The highest rate was among the 4-5
years old and the rate of infection found to be associated to quality of food,
water taken and where they were living (Umutoni, 2010; Mukagihana, 2011;
Mugaju, 2011).
II.3. INFECTIOUS AGENTS OF
GASTROINTESTINAL INFECTIONS
There are many infectious agents causing gastrointestinal
infections. But they are mainly bacteria, viruses and parasites. All may have
common clinical features of nausea, vomiting, diarrhea and anorexia (Prescott
et al., 2005).
II.3.1. Protozoa
Human intestinal protozoa infections are found worldwide, in
both developing and industrialized countries. Protozoa produce diarrhoeal
diseases by infecting the small or large intestine, or both. For example,
Entamoeba histolytica can become a highly virulent and invasive
organism that causes a potentially lethal systemic disease (Ali et al.,
2008).
Giardiasis and Cryptosporidiosis are important causes of
diarrhea in children; the latest is particularly associated with growth failure
and malnutrition. They also cause water -borne and food-borne outbreaks (Ali
et al., 2008).
II.3.1.1. Amoebiasis (Amebiasis)
Amoebiasis refers to infection of human intestinal tract
caused by protozoan parasite Entamoeba histolytica (Cedric, 2004).
Amoebiasis is a major cause of parasitic death worldwide. About 500 million
people are infected and many as 100.000 die of Amebiasis each year
(Prescott, 2005). It is estimated that 40-50 millions cases of amoebic colitis
and liver abscess occur annually with 40 000 to 110 000 deaths
(WHO/PAHO/UNESCO report, 1997).
Entamoeba histolytica has a worldwide distribution
and the infection occurs all over in Africa. It is mostly found in subtropical
and tropical countries where the prevalence may exceed 50% (Cedric, 2004).
II.3.1.2. Gardiasis
Giardia, the causal agent of gardiasis was discovered
by Van Leeuwenhoek in 1861 when he examined his own stool. Giardia is
worldwide distributed and an estimate of 200 million people is infected each
year. Giardiasis is endemic in children day care centers in the United States
with estimate of 15% to 50% of diapered children being infected. It was found
in 10% of children rising in Cairo and the highest prevalence rate have been
recorded in the studies from Guatemala in which in one cohort had infection by
3 years of age, or from the Gambia where the prevalence was 45% in children
with diarrhea (Prescott et al., 2005).
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