Thanks to friend and colleague Joan Acosta for sending the link to this report in The New Yorker: What We Don’t Know About Ebola. Excerpt:
Finding the hidden pool of the virus would go a long way toward eradicating it. At first, researchers thought that the hosts were chimpanzees, gorillas, and other primates. Now it is clear that these animals get sick and die too quickly to hold on to the virus for long.
Although Ebola may be carried without symptoms in fruit bats for extended periods, as the media has widely reported, additional candidates keep emerging—a certain strain of the virus was found to be harbored by pigs in the Philippines in 2008, for example.
To discover the source of Ebola, we should send trained field workers into the bush to test, isolate, and then kill infected animals to remove them as a food source and limit their capacity to transmit the virus.
There is precedent for this kind of strategy. In the bird flu outbreaks of 2005 through 2007, certain flocks of chickens in Asia carried deadly strains of influenza. Chinese public-health officials were able to target and slaughter them, snuffing out an epidemic that otherwise could have spread with great speed and ferocity, and significantly reducing the chance of flare-ups afterward.
Although we know that bodily fluids are contagious, we still don’t have a definitive picture of how the virus enters the body’s cells. But learning the biology of Ebola infections is necessary for designing and deploying effective drugs and vaccines. Unlike H.I.V., which can only infect a limited set of cell types in the body, Ebola is promiscuous and attacks white blood cells, the cells that line our vessels, and cells that make up our liver, adrenal glands, and airways.
Research studies have suggested at least three potential paths that the virus can take to invade our tissues. In one sequence, Ebola attaches to a protein on the surface of a cell that is meant to transport cholesterol. After Ebola has hijacked the surface protein, it sneaks into the cell and rapidly proliferates. (That transport protein is ubiquitous in the body, because all our organs require cholesterol in order to function normally.)
Other experiments have indicated that Ebola can commandeer a protein called TIM-1, which is widely distributed in conjunctiva, the insides of our eyelids, and in our cornea. Despite taking precautions with gloves and facemasks, health-care workers who have become infected may have inadvertently brushed a finger near their eye, giving the virus access to TIM-1.
