Why Zika Never Exploded In Africa: New Study : Goats and Soda - NPR

The species comes in two major types: the forest-dwelling form, which predominates in Africa, and the human-loving form, which lives in Latin America and Asia.

In contrast, the human-loving form really loves to feed on human blood, Vosshall says, and spends its life near people.

Lambrechts and his team also wondered if the human-loving mosquito, the one in Latin America, is somehow more susceptible to infection with Zika than the forest-dwelling form and better at transmitting the virus.

They took mosquitoes from Africa, Asia and Latin America and fed them blood infected with varying amounts of Zika virus.

The mosquitoes from Africa — the forest-dwelling form — were more resistant to Zika infection than the human-loving mosquitoes from Latin America.

The African mosquitoes picked up the virus from the blood meal only when it contained higher concentrations of Zika.

In contrast, the human-loving mosquitoes got infected from the blood even when it contained much fewer Zika particles.

Regions with mosquitoes that are highly susceptible to Zika infection (i.e., Latin America) have had large, explosive outbreaks.

The ones in Africa are less likely to pick up the virus from infected blood and less likely to have Zika virus in their saliva after feeding on an infected animal

These new findings help explain why Zika all of a sudden became a problem in Latin America, Vosshall says, but hadn't been a problem in Africa

"Now this paper shows the human-loving form is also really good at growing Zika virus [inside its body]."