Exploring Uganda's Zika Forest, Where the Infamous Virus Was First Identified

The Zika forest in Uganda, where the Zika virus was discovered in 1947.
A signpost leading to Zika forest in Uganda, January 29. The Zika virus was first discovered in the forest in 1947, but there have been very few confirmed cases locally in recent years. ISAAC KASAMANI/AFP/Getty Images

The Zika virus currently wreaking havoc in Brazil and Latin America was first discovered more than 5,600 miles away in an overgrown tropical forest near the Ugandan city of Entebbe.

The virus has been linked to a massive Brazil outbreak of microcephaly—a condition where children are born with underdeveloped brains and small heads. Between October 2015 and January 2016, more than 4,000 cases of microcephaly were recorded in Brazil, compared to just 147 cases in 2014. The potential link between Zika and microcephaly has been declared by the World Health Organization (WHO) as a Public Health Emergency of International Concern (PHEIC)—meaning it poses a global threat and requires an international response.

But parts of the population in East Africa, including Uganda and Kenya, could already be immune to the virus, according to a medical expert and WHO official.

The virus was first identified in rhesus monkeys in Uganda's Zika forest in 1947, before being found in humans in Uganda and Tanzania in 1952. While there is a dearth of research on Zika in Africa, outbreaks of the virus on the continent have previously been recorded, according to the WHO.

Zika is transmitted by the aedes aegypti mosquito, which is widely distributed in Africa. The mosquito is also a primary vector for several other viral diseases—including dengue fever, yellow fever and chikungunya—that are common across the continent. Despite the presence of the mosquito vector in countries like Kenya and Uganda, only a handful of cases of Zika have been confirmed in recent years. Just two cases have been confirmed in Uganda in the past seven decades, the BBC reported. Researchers at the Uganda Virus Research Institute—that lies just a few kilometers away from the Zika forest—and the Kenya Medical Research Institute in Nairobi have recently announced separate studies to collect more data on Zika prevalence in the region.

Yet the presence of Zika antibodies—proteins in the blood that target and neutralize specific bacteria or viruses—have been recorded in people in Kenya, indicating immunity to the virus, according to Dr Ahmed Kalebi, chief executive of East Africa's branch of the Lancet Group, a pathology research organization. "If people haven't been immunized or vaccinated against Zika but they have antibodies to Zika, it means that the virus must have gotten into them at one time or another in their lives," says Kalebi.

There is a lack of research on microcephaly cases in Africa, though The Guardian reported that Zika has not been linked to any instances of the condition on the continent. Kalebi says that, while the link between Zika and microcephaly is still unclear, people in East Africa need not be alarmed about the current outbreak. "It might well turn out to be that Zika is just a red herring and there is something else additional to Zika that makes those babies get microcephaly and not others," says Kalebi.

The WHO has warned that the virus is likely to spread throughout North and South America, but could also move to other continents. Thirty-three countries across the Americas so far have reported the presence of the virus in their populations. Besides Brazil, the virus has infected more than 25,600 people in Colombia, with more than 3,100 of them being pregnant women.

So far in the current outbreak, the only African country to report Zika cases in any significant number is Cape Verde—a collection of islands in the Atlantic Ocean that lie hundreds of kilometers off the coast of West Africa. Between September and December 2015, more than 4,700 suspected Zika cases were reported in Cape Verde, according to the WHO. No cases have been reported on the African mainland.

Christian Lindmeier, the WHO's lead spokesman on the Zika virus, says the idea that people in East Africa could be immune to the disease is "a very interesting theory" but says that a lack of evidence means it cannot be stated definitively. One of the main reasons why Brazil and other Latin American countries are suffering with such an influx of Zika cases, according to Lindmeier, is because the populations had never previously been exposed to the disease, unlike those in East Africa. "It's very possible that parts of Africa or other parts [of the world] might already be quite immunized and therefore would not experience the same sort of outbreak," says Lindmeier.