October 31, 2014

Hopes for the survival of Australia’s wild koalas have been boosted by test results for a new vaccine against chlamydia, a disease that is ravaging populations of the beloved marsupial. One of vaccine’s developers told news media that the sexually transmitted disease, which causes blindness and infertility, is one of the “tipping points” contributing to the decline of the species. Estimates of the current size of the koala population vary from several hundred thousand to as few as 43,000. Conservationists estimate that the animal’s numbers in New South Wales and Queensland have fallen by as much as 40 percent since 1990. In 2012, the government of Australia, for the first time, listed koalas as a vulnerable species in the states of New South Wales and Queensland and in the Australia Capital Territory. Other threats facing koalas include habitat loss, wild and domestic dogs, urban development, mining, and climate change.

For the trial, researchers captured  60 wild koalas and fitted them with radio collars so the animals’ movements could be tracked. They then vaccinated 30 of the koalas. Some of these koalas were healthy; some were infected by chlamydia; some had already developed symptoms of the disease. The researchers found that none of the vaccinated koalas developed the disease. In addition, those animals already infected did not go on to develop chlamydia. And nearly all of those that had symptoms improved. Among the nonvaccinated group, more of the koalas became infected and the condition of animals with chlamydia worsened.

A female koala carries her joey (young) on her back. Wild koala populations have fallen because of the bacterial infection chlamydia. Scientists are working on a vaccine to prevent and treat the infection in koalas.  (Dave Watts, Tom Stack & Associates)

The researchers plan to continue their tests for another year. If results remain positive, wild koalas could be vaccinated for their protection. “We hope to specifically show a positive effect of the vaccination disease, not just infection, as well as female reproduction rates,” one of the researchers said.

Additional World Book articles:

• Endangered species