ITN research in Africa
Below is some news from Christian Lengeler and his co-workers on ma-
laria control by use of insecticide-treated nets.
In our February 2001 paper in the British Medical Journal and our
April 2001 paper in the Lancet, our collaborative teams of scientists
at the Ifakara Health Research and Development Center and the Swiss
Tropical Institute have been able to show that insecticide-treated
nets (ITN) distributed through a large-scale social marketing program
had a substantial impact on malaria in small children in a highly en-
demic area (around Ifakara, Southern Tanzania).
The introduction of ITNs sold through health services and commercial
outlets led to an overall increase in coverage of small children with
ITNs from 10 to 61%. As a result, there was a substantial increase of
9g/l Hb in this population and the risk of having parasitemia was re-
duced by 62% and the risk of having severe anemia was reduced by 63%.
There was much evidence that a healthy commercial market for nets was
created during this time - to the extent that other net brands com-
peted successfully against the socially marketed brand.
This is the first good proof that ITNs seem to work in the "real
world" and it is a good basis to plan large-scale programs from. The
process of national up-scaling is in full swing in Tanzania and it is
a very exciting process. According to the authors, ITNs are without
any doubt a great tool to make a major dent into the malaria burden.
The British Medical Journal paper:
Volume 322:270-273 - February 2001
Impact on malaria morbidity of a program supplying insecticide
treated nets in children aged under 2 years in Tanzania: community
cross sectional study
Mosquito nets treated with insecticide and distributed as part of a
large scale social marketing program can substantially reduce the
prevalence of malaria and anemia in very young children in Tanzania,
finds a study in this week's BMJ. This strategy has high potential in
the control of malaria in sub-Saharan Africa, say the authors.
Abdulla and colleagues investigated a random sample of 748 children,
aged under 2 years, living in 18 villages in southwest Tanzania. The
first survey was done at the time of launching the social marketing
campaign (June 1997), and two other surveys were carried out at the
same period (June to August) in the subsequent two years. They found
that ownership of treated nets rose rapidly, from 10% to 61%. The
prevalence of severe anemia decreased from 49% to 26% in the two
years studied, and the mean Hemoglobin level in the children rose
from 80g/l to 89 g/l. Treated nets had a protective efficacy of 63%
against both malaria and anemia.
Treated mosquito nets might therefore be able to deliver feasible and
effective malaria prevention on a large scale in areas where malaria
is highly endemic, conclude the authors.
The Lancet paper:
Volume 357, Number 9264- 21 April 2001
The research team established a test system based on the "social mar-
keting" of mosquito nets, mixing the advertising, packaging and sell-
ing techniques used to market items for profit with government subsi-
dies to remove the costs associated with the goal of reaping a
In two districts of southern Tanzania--home to approximately 480,000
people in 144 scattered villages--Schellenberg and her colleagues set
up a 3-year program based on this distribution approach. Beginning in
1996, the researchers held meetings with religious, commercial,
health and local government leaders to assess the general perceptions
concerning malaria held among this regions' households.
Based on their findings, Schellenberg's team then developed packag-
ing, educational material and a selling network designed to get local
people to buy and use the nets. Although the nets were not free, par-
tial government subsidies were given to wholesalers to keep prices
By the end of the trial, there was a 16% drop overall in mortality
among children under the age of 5 and a 27% drop in the risk of death
shortly after birth. The authors attribute this reduction to the fact
that by May 2000, almost 55% of all the surveyed households were us-
ing insecticide-treated nets for their infants--up from just 10%
three years earlier.
The researchers further note that the use of nets was higher in those
areas where the socially marketed nets had been available the long-
est. The nets seemed to be equally effective at preventing malaria
infection regardless of an individual's age or the time of year or
"In the small area we covered, 100 deaths were prevented as a result
of this program every year," said Schellenberg. "And that's in just
two districts in Tanzania. And Tanzania has over 100 districts, so if
you start multiplying things up it can get very dramatic at a na-
Schellenberg and her colleagues conclude that both the net and the
manner in which it was distributed can be effective weapons against
malaria. They estimate in Tanzania alone, a nationwide program could
save the lives of up to 10,000 children if only 30% of all households
were to use the nets.
And while acknowledging that the program fell short of being a per-
fect solution, the researchers express hope that newly developed
technologies, such as permanently treated netting, could help to ad-
dress some remaining issues, such as insufficient use of home net
Andrea Egan, PhD
Multilateral Initiative on Malaria
Fogarty International Center
National Institutes of Health
31 Center Drive MSC 2220
Building 31, Room B2C39
Bethesda, MD 20892, USA
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