Progress, puzzles in halting malaria | Harvard GazettePosted: April 1, 2013
Jessica Cohen, assistant professor of global health at the Harvard School of Public Health (HSPH), was part of a team brought to Zanzibar to help the government determine a path to control malaria in the future, either by maintaining the present low level or by pushing forward with eradication efforts.
The nature of malaria makes eradication extremely difficult, Cohen said. The disease can lie dormant in the liver for years, breaking out after control efforts have eased. The ability of the mosquitoes that carry the parasite to bite a number of people means that one case can lead to many others — and that means efforts that fall short of eradication, even if they come very close, may be reversed in short order.
Cohen’s analysis of Zanzibar said that the disease would be eliminated in five years if everyone on the island, which is home to more than a million people, slept under bed nets. If just 65 percent used the nets — a high compliance rate — eradication would take 22 years.
But if the use of bed nets fell to 50 percent, prevalence of the disease would start rising again, to 5 percent from 2 percent in just three months. If the use of bed nets fell to 35 percent, it would skyrocket to 18 percent in just three months.
“These gains can be erased in months,” Cohen cautioned.