A study conducted by Craig Packer, an ecologist at the University of Minnesota in St. Paul, showed that in the two years, extreme drought followed by heavy seasonal rains created ideal conditions for two diseases - Canine Distemper Virus (CDV), and infestations of a tick-borne blood parasite called Babesia to converge. Normally, the diseases do not occur simultaneously.
The infections killed one-third of the Serengeti lion population in 1994, and one-third of the Ngorongoro Crater lion population in 2001. Packer and other scientists analysed 30 years of data and found that the lion populations have easily withstood individual outbreaks of CDV and Babesia. However, when CDV-weakened lions fed on drought-weakened prey that had subsequently fallen victim to flood-induced infestations of Babesia-carrying ticks, huge losses occurred in the lion populations. According to Sonia Altizer, an expert in wildlife diseases at the University of Georgia in Athens, Packer's study “lays out mechanistically how a climate anomaly could allow a combination of pathogens to have a lethal one-two punch." Packer warns that future extreme weather anomalies caused by climate change will give rise to a growing number of deadly co-infections in both wildlife and humans.
August 2008
