COPENHAGEN, Denmark, Aug. 25 (UPI) — The incidence of malaria in many African countries south of the Sahara is falling rapidly but Danish and Tanzanian researchers say they don’t know why.
The mosquito carrying the malaria parasite has practically disappeared from many villages without organized mosquito control, but it is not known whether malaria is truly being eradicated or just in a lull before returning with renewed vigor, a University of Copenhagen release said Thursday.
“Many of our fellow malaria researchers think that the fall in countries such as Tanzania, Eritrea, Rwanda, Kenya and Zambia shows that all the control programs are working, particularly the use of mosquito nets,” Copenhagen professor Dan Meyrowitsch said.
“That just isn’t the whole story,” Meyrowitsch, of the university’s department of health services research, said. “For more than 10 years we have been collecting and counting the number of mosquitoes in Tanzanian villages. The number in our traps fell from 5,300 in 2004 to just 14 in 2009, and these were from villages without mosquito nets.”
The decrease in the malaria mosquito count seems to be connected to a fall in precipitation, he said, possibly due to global climate change.
“From 2003 to 2009 the volume of precipitation was more stable, but the rain was more chaotic and fell outside the rainy season. And this may have disturbed the natural cycle of mosquito development,” he said. “Of course it is great that the number of malaria-related fatalities among children has fallen drastically in the last five or six years, but we need to know why!
“Unless we find the answer we will not be able to predict when the malaria mosquitoes will come back, and that could rapidly prove critical,” Meyrowitsch said, noting that many children and adults have not been exposed to malaria in the last five or six years and have lost or failed to develop immunity to the parasite.