A killer up close
Ebola belongs to a family of viruses known as filoviridae, which take their name from their serpentine, filamentous structure (see Figure 1). Filoviridae fall into two broad categories known as Ebola-like and Marburg-like viruses. In the original Ebola outbreak in Yambuku, situated along the Ebola River, 280 of the 318 identified cases died. Soon thereafter, an additional 284 cases and 151 deaths occurred in nearby Sudan. In Yambuku, the small local hospital was shut down, after 11 of its 17 staff members died.
The likely reservoir for the disease is bats. Primates including monkeys can become infected from eating bats or from fruit the bats may have dropped. Infected animals can then spread the disease to humans through bites, or when the primates are consumed for fooda practice prevalent in some regions of Africa.
The course of the disease is pitiless, sometimes producing hemorrhagic fever, which causes severe bleeding from mucous membranes, including the gastroinestinal tract, eyes, nose, vagina and gingiva. The very high mortality and gruesome symptoms of the disease have riveted public attention and have been the focus of numerous films and books, notably Richard Preston's The Hot Zone.
Arntzen notes that while no human vaccine against Ebola currently exists, a number of strong candidates have emerged. While some have yielded good results in animal models, in terms of protection against the virus, they have practical shortcomings. "All of these existing vaccine candidates are genetically modified live viruses," he says. Vaccines of this sort require very careful conditions of storage and have a tendency to lose potency over a period of months. "If you've got something that you're g
|Contact: Joseph Caspermeyer|
Arizona State University