A field trial of a vaccine against koala chlamydia has started well, raising hopes for preventing the number one killer of the much loved marsupial.
Even in a continent known for its charismatic animals, koalas have a favored place, but currently they are in decline. Threats include logging, dogs, cars, and half of wild koalas are infected with chlamydia, often fatally. While disease-free islands are often overpopulated with koalas, numbers in some mainland areas have dropped by 80% in 10 years, and the species is listed as threatened in most of its range.
Koalas and humans are not the only species to be infected by members of the Chlamydiaceae family of bacteria. However, where most humans with the Chlamydia trachomatis bacterium are asymptomatic, koalas routinely suffer blindness, painful cysts and infertility, along with urinary tract infections that can turn toxic from the two species that affect them. Antibiotics are effective if administered early, but this requires several months in captivity.
However, when you are as cute as a koala, wallets have a way of opening. A consortium including two universities, private institutions and local and state governments have developed a vaccine that has shown success in the lab. The first field trial involved the capturing, radio-collaring and release of sixty koalas near Moreton Bay. Half the subjects were also vaccinated, with the others left as a control.
Professor Peter Timms of the University of the Sunshine Coast says the first news is that, in keeping with the Hippocratic Oath, the study did no harm. “This large trial has confirmed that the vaccine is safe to give to not only captive koalas, but also koalas in the wild,” says Timms.
Moreover, vaccinated animals showed a strong immune response, and the disease did not progress in those already infected, unlike three members of the control group. Vaccinated females also appear more likely to be carrying joeys. The results are yet to be published however, and Timms says a longer timeline is needed to confirm success.
“While these results are very promising, the trial will extend for at least another year. We hope to specifically show a positive effect of the vaccine on disease, not just infection, as well as female reproductive rates,” says Timms, adding, “We feel compelled to start using this vaccine more broadly, especially when we know that it is safe and has some definite positive benefit to the animals.” The University needs $2.5 million to extend the vaccination program to a larger population and is seeking donations.
The researchers add that the work could lead to vaccines against related bacteria that infect humans and many other animal species. So far the anti-vax movement has not alleged the program is producing autistic koalas, but it is probably only a matter of time.