It was recently revealed that in 2012 Australia experienced its largest outbreak of Q fever associated with a single farm in the country’s history, according to a report that aired earlier this month on the Australian Broadcasting Corporation program Landline. At least 24 people contracted Q fever during an outbreak – that is still ongoing, at least among the animals – on a goat dairy farm in the state of Victoria in southeastern Australia.
Victoria is the smallest of the Australian states and home to the city of Melbourne, where more than 75% of Victorians live. Victoria is also the center of dairy farming in Australia, and more than 14 million sheep and 5 million lambs graze over Victorian farms. And the region boasts one of the biggest dairy goat farms in the country. The affected farm located near Ballarat – a city borne out of the gold rush days of the 1850s and located 65 miles outside of Melbourne – is a big enterprise with three dairies and more than 100 staff. They milk thousands of sheep and about 5000 goats twice daily, according to the report.
Q fever is a zoonotic disease – that is, a disease passed from animals to humans – caused by a bacterium called Coxiella burnetti. In the environment, this bug is extremely hardy as it can morph into a spore-like form that can sit in the soil for years before it encounters its next host. While the bacterium can infected many different species of animals, livestock including cattle, sheep, and goats are the primary reservoir hosts for this bug. In them, the disease often manifest abortion, and the bacteria are excreted in the milk, urine, and feces of infected animals.
In hindsight, the outbreak began in 2011 when a few people at the farm, including the owner’s own daughter, began getting sick with flu-like symptoms. However, the identity of the disease was not known until late 2012 when one of the staff was diagnosed with Q fever. “Most, but not all, of the infected people worked directly with animals on the farm,” Dr. Simon Firestone, a senior veterinary lecturer at the University of Melbourne, said in the report. It is even believed that one of the farm employee’s spouse became infected from washing her husband’s contaminated clothes.
People usually contract Q fever by inhaling air containing airborne dust particles contaminated with dried placental fluids or excreta of infected animals, which can contain the Coxiella burnetti bacteria in high numbers. Humans are often very susceptible to the disease, with as little as 1 or 2 organisms required to cause disease. In people, symptoms of Q fever can include fever and severe head and muscle aches. In more severe cases, infection can result in heart valve damage, which can be fatal. Research has shown that in about 20 percent of people who contract Q fever end up with long-term health problems including chronic fatigue, muscle pain, and even depression.
Fortunately, there have been no new cases of Q fever in people on the farm; however, the disease among goats is ongoing with infection rates as high as 30 to 40 percent of the goats, Dr. Firestone said in the report. “[The disease] is fairly endemic on the farm now,” he went on to say.
This farm – which was not named in the report for obvious reasons – produces around 13,000 liters of sheep and goat milk a day and makes yogurt and cheese. Their milk is pasteurized and officials insist that you can’t catch Q fever from pasteurized products.
By the way, the “Q” in Q fever stands for “query,” not for Queensland, where the disease was first described in 1935.
Chris A. Whitehouse is a microbiologist and science writer who lives in Maryland. He writes extensively on emerging infectious diseases of humans and animals.