To prevent future outbreaks of Ebolavirus from occurring, investigating which animals are hosts for this virus and most likely to contribute to disease spread is essential.
CEID’s John Paul Schmidt, Patrick Stephens and John Drake worked with a team of infectious disease scientists collecting extensive species data on Ebolavirus infection status and mortality. This research compiles the first comprehensive evaluation of reservoir status (which animals can be infected by and/or spread Ebola Virus) for mammals in Africa.
The source of infection from previous Ebolavirus outbreaks was traced back to gorillas, baboons, and chimpanzees. Though animals such as gorillas and chimpanzees can host the virus, they are likely to die from infection, and because of this high mortality rate from infection, these animals are less likely to transmit the virus to other species.
In this analysis, twenty-one African mammal species were examined, ranging from bats to macaques. This analysis included factors such as life history traits (ex: length of pregnancy, litter size, maximum lifespan), variation in diet, brain size, and geographic distance to the nearest spillover site (where Ebolavirus was transmitted across species). The species were also characterized by their ability to fly, as to differentiate between bats and other species.
Infection and mortality from Ebolavirus was found to be strongly associated with evolutionary history and life history traits. Ebolavirus infection was measured by PCR (detects presence of pathogen) and antibody tests (detects pathogen antibodies). Non-volant species (species that cannot fly) that have comparatively fewer litters each year and longer pregnancies than other species examined, were more likely to die after being exposed to the virus. Bats and other species with fast reproduction and short lifespans, such as mice, were more likely to survive after being infected. Species that were extensively sampled and species that consumed significant levels of fruit in their diets were likely to test positive for Ebolavirus.
Species were categorized into four different groups. Species with high likelihood of past Ebolavirus infections and high likelihood of death after exposure were classified as “dead-end hosts”. These species are unlikely to carry the virus for long periods and are not likely to be major sources of disease spread. Species with high probabilities of past infections and low likelihood of mortality fall into the potential “reservoirs” grouping. These species are expected to carry the virus for longer, and are more likely to infect other species. “Low exposure and susceptibility” species are rarely infected and are unlikely to die even if exposed to infection, and the “susceptible but rarely exposed” group encompasses species who have a low likelihood of Ebolavirus infection, but high mortality if exposed. Further sampling across species throughout different times of the year would be beneficial in expanding this field of research.
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By: Brenna Daly