Intermittent Preventative Treatment (IPT) Against Malaria

Read the full news story by Gretchen Vogel in Science. (Science 9 December 2005: Vol. 310. no. 5754, pp. 1606 - 1607. Subscription necessary.)

"Evidence so far suggests that this simple and inexpensive treatment, called IPT for intermittent preventative treatment, may significantly slash the disease burden in young children. Nearly 1 million children die each year of the disease.....

"In an effort to weigh the costs and benefits as quickly as possible, researchers in 2003 formed the IPTi consortium. (The 'i' is for infants.) The group, which includes WHO, UNICEF, and scientists from 14 institutions in 11 countries, received $28 million in funding from the Bill and Melinda Gates Foundation......

"The first data on IPT in infants--which helped inspire the formation of the consortium--were remarkable. In 2001, Schellenberg and his colleagues reported that in a study of 700 babies in Tanzania, IPTi cut rates of clinical malaria by almost 60% compared with rates in infants who received a placebo. Another Tanzanian study in 2003 showed that IPTi reduced malarial fevers by 65% in the first year of life.

"But more recent studies suggest that such dramatic results can't be expected everywhere. In a trial of nearly 1500 infants in Ghana, described in October in the British Medical Journal, treatment cut malaria episodes by just 25% compared to a placebo. Hospital admissions for anemia, one of the most dangerous malaria complications, were 35% lower in the treatment group......

"At the site in Ghana, the disease is transmitted during the 6-month rainy season, when residents face about 10 times the rate of infective mosquito bites as faced by those in the Tanzanian study. Greenwood notes that for a subset of Ghanan babies who received their first two doses during the rainy season, results were nearly as good as those in Tanzania; it reduced clinical cases of malaria by 52% and anemia by 72%.

"But mosquito bite rates and differing seasons of infection can't explain all the differences seen in IPTi trials. Results from a trial in Mozambique, first reported last month in Yaounde, 'are not as exciting as we'd hoped for,' admits Andrea Egan of the University of Barcelona in Spain, who coordinates the IPTi consortium. A study of 1500 infants, also living in an area of moderate year-round transmission, showed a 22% reduction in clinical malaria rates compared to rates in babies who received a placebo but no difference in anemia rates."

I have always been told that the most likely strategy to be effective against malaria is a mixed strategy, combining a wide variety of measures. Even if a malaria vaccine is developed, it will probably not be a "silver bullet" which alone can erradicate the disease. A mixed strategy will probably still be required. IPT may well be an important tactic to be included in future strategies.