In 1999, the New York State Department of Health asked me to test brain samples from people in Queens experiencing encephalitis, or brain inflammation. Surprisingly, we found they were infected with West Nile virus, a mosquito-borne virus that had never been reported before in North America. How did a virus endemic in Africa and the Middle East end up in Queens?
At the time, scientists posited that there were stowaway mosquitoes on a flight from Tel Aviv. It seemed plausible that these stowaways fed on infected geese in Israel before infecting birds in New York. Local mosquitoes that fed on the New York birds then fed on people, and now we had an outbreak.
Like today with the origins of Covid-19, there were other, often polarizing, theories. Back in 1999 there were claims that the virus had been bioengineered by Saddam Hussein.
Although the global community never officially pinned down the provenance of the West Nile virus, the outbreak was brought under control by reducing the mosquito population in Queens — West Nile nonetheless remains the leading cause of mosquito-borne disease in the continental United States. Since 1999 it has infected at least seven million people, resulting in more than 51,000 cases of encephalitis and more than 2,300 deaths.
Similarly, in 2008 my team investigated a hemorrhagic fever outbreak with an 80 percent case fatality rate in Zambia and South Africa. Viral sequencing led to identification of a new virus named Lujo (for the location of the first case in Lusaka, Zambia, and the subsequent outbreak in Johannesburg, South Africa). We predicted it would be sensitive to an existing antiviral drug, and thankfully it was. Although four people died, we saved the last person infected and interrupted further transmission. But 15 years later we still don’t know how the first person became infected, although we suspect that the reservoir was a wild rodent.
Finding the origin of a viral outbreak can be incredibly difficult, even with full government cooperation and the best available technologies. It’s important to try, because the insights into how a virus emerged may be useful in reducing the risk of future outbreaks. But these efforts and debates over uncertainties cannot come at the expense of action. We cannot wait for answers that may never come before doing what must be done to prevent the next pandemic. [Continue reading…]