Balantidium coli has a worldwide, or cosmopolitan, distribution. It is reported to be more common in the
tropics, yet this observation may be confounded by others factors. For example, the keeping of pigs is an
inexpensive and common practice in tropical regions and many developing
countries in the tropical region lack proper water systems and livestock
containment structures for much of the poor, rural population. Countries that are known to have had
incidences of Balantidium coli infection include, Bolivia, the
Philippines, and Papua New Guinea.
Few studies have been
conducted to determine the prevalence of infection. Those surveys that have been done generally report prevalence
rates of less than 1%. A study was recently
conducted on Balantidiasis in Aymara schoolchildren of the northern Bolivia
Altiplano. The Aymara are indigenous
Indians who practice livestock breeding, including pigs, and agriculture. They region is impoverished and has overall
poor health. Other parasitic diseases,
such as cryptosporidiosis, are considered endemic to the northern Bolivian
Altiplano.
Researchers
collected stool samples from schoolchildren in 22 communities over a five-year
period (2,124 total children surveyed) and examined them for the presence of Balantidium
coli. Half of the communities had
some Balantidium coli infection.
Still, prevalences were low, ranging from 1% to 5.3% with an overall
prevalence of 1.2%. The children did
not show symptoms of Balantidiasis, and were apparently asymptomatic
carriers. Investigators also collected
stool samples from 50 pigs in the communities, and detected the presence of Balantidium
coli in 54% of them. Nearly all of
the families in the communities studied kept pigs. Though low, the prevalences found are among the highest to be
reported and infection with Balantidium coli must be considered as a
disease endemic to the area.
Almost
all of the children surveyed were infected with one or more parasites
(protozoan or worm/helminth species) in addition to Balantidium coli. Co-infections likely aggravate the damage
wrought by each individual parasite, and they likely share common sources of
infection (i.e. contaminated water). Public Health Interventions aimed at
Balantidium coli control can reduce the prevalence of other parasitic
diseases, too.
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