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Researchers first identified the Zika virus in 1947 after a fever developed in a rhesus monkey

Many scientists believe the 2007 strain of Zika has mutated from the original virus, with increased virulence

Zika Forest, Uganda CNN  — 

The turnoff into the Zika Forest is easy to miss, just a small break in the tree line along the main road between Entebbe Airport and Uganda’s capital, Kampala. A worn-out sign announcing its start only comes into view after a journey down a small dirt path.

The explosive spread of the Zika virus may have caught the world by surprise, but its namesake, the forest preserve near the edge of Lake Victoria, isn’t a place to just stumble on to. The researchers who have been coming here for more than a half-century come with a purpose: to study viruses and the mosquitoes that carry them.

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A well-worn sign is the only indication of the start of the Zika forest, Uganda's only preserve devoted entirely to science research.