Geographical distribution and useful facts and stats Soil-transmitted helminth

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Geographical distribution and useful facts and stats

 

 

Geographical distribution

 

Soil-transmitted helminth (STH) infections are widely distributed in

tropical and subtropical areas, and since they are linked to a lack of

sanitation, they occur wherever there is poverty.

 

In contrast, since schistosomes need water, schistosomiasis is much

more focally located around local water bodies which contain the

appropriate snail vectors. Water-resource developments, dams and

irrigation channels aggravate the transmission of schistosomiasis as

they provide the perfect habitat for the snails. Between 1950 and

1990, the number of damns worldwide increased dramatically from about

5000 to 36 000, with a consequent rise in schistosomiasis in

sub-Saharan Africa.

 

Useful facts and stats

 

Numbers of people affected:

The number of people affected by schistosomiasis and soil-transmitted

helminth (STH) infections is staggering. Around 2 billion people

harbour these infections: in other words, worms infect more than a

third of the world's population.

 

Morbidity:

Some 300 million people are severely ill with worms and of those, at

least 50% are school-age children.

 

Burden of Disease:

In 1993, intestinal worms were ranked first in the main causes of

disease burden in children aged between 5 and14 years old.1

 

In 1999, WHO estimated that schistosomiasis and STH infections

together account for 40% of all tropical disease burden excluding

malaria, and that infectious and parasitic diseases – most of which

are preventable or treatable – are the primary causes of death

worldwide. 2

 

Mortality:

Death is in fact a rare consequence of parasitic infection, but

because of the massive number of people affected worldwide, the number

of deaths is substantial. In Africa alone, the death toll due to

schistosomiasis may be as high as 200 000 every year.

 

1 World Development report 1993.

2 World health report:Making a difference,. Geneva, World Health

Organization, 1999.

 

 

 

 

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