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Ebola outbreaks may worsen with global warming

Ebola outbreaks may worsen with global warming

Ebola outbreaks may worsen with global warming
mongabay.com
November 14, 2006

Ebola outbreaks are linked to wildlife and climate according to new research published in the journal Transactions of the Royal Society of Tropical Medicine and Hygiene.



Ebola, a deadly hemorrhagic fever made famous in Richard Preston’s book The Hot Zone, periodically emerges to affect human populations in Central Africa. Until now, scientists had little understanding of the pattern behind Ebola outbreaks.



“Some researchers have hypothesized that outbreaks of Ebola are randomly-spaced periodic outbursts, while others have suggested that Ebola has spread like a wave surging over the Central African landscape,” said Sally Lahm, a visiting professor at the University of California at San Diego (UCSD) and the primary investigator of the study. “Our results are intermediate between these two views. There is a perceived pattern to the way the virus spreads, but it is not simply a wave affecting everything in its path, since apparently healthy mammal communities thrived in close proximity to Ebola epidemic sites.”

Lahm’s results are based on her decade spent examining wildlife deaths from the disease in Gabon and Republic of the Congo. She found that Ebola is considerably more common than initially thought.

“The transmission of Ebola within animal populations is much more widespread than previously believed,” explained Lahm. “Ebola appears to spread both within species and between different species of animals.”



Silverback gorilla in Gabon. Ebola outbreaks in gorillas are relatively common in Central Africa.

Lahm then worked with Maryvonne Kombila, the director of the Department of Tropical Medicine and Parasitology at the University of Health Sciences in Libreville, Gabon and with Robert Swanepoel, the director of the Special Pathogens Branch of the National Institute of Communicable Diseases in Sandringham, South Africa, to determine “the extent of human exposure to Ebola within Gabon.” The researchers found that some people exposed to the virus lived where it had not been recognized but found relationships between human exposures and the outbreaks recorded in wildlife.

“Based on their findings, the researchers were able to identify relationships among previously documented Ebola outbreaks in humans and wildlife in Gabon and RoC that initially seemed disparate and unrelated. They proposed that the virus first spread southwest across Gabon. It then looped back toward the northeast from sites in western or central Gabon and caused the most recent outbreaks in RoC,” exaplined a news release from UCSD.

The researchers also found a link between Ebola outbreaks and climate: “Illness and deaths among animals were most prevalent during periods of prolonged drought-like conditions in the rainforest, which indicates that severe environmental stress may facilitate disease transmission.” With some climate models projecting drier conditions in Central African rainforests due to climate change, it’s possible that incidences of Ebola could increase in the future.



The researchers say that public education is the best way to reduce the transmission of the disease from wildlife to human populations and that wildlife monitoring “in collaboration with rural African residents could provide information essential for protecting public health as well as comprehending the ecology of the disease.”

The researchers note that still much remains to be learned about the disease, espcially how the virus spreads between species.

“Our study provides more pieces of the puzzle, but at the same time it is enlarging the puzzle,” said Lahm.






This article is based on a news release from UCSD.

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