New research from University of Sydney finds that rural residents are at increased risk of catching the highly infectious bacterial infection Q fever, including those residents who are not currently in high risk groups recommended for vaccination.
Q fever is a highly infectious bacterial disease that can cause a severe flu-like illness. It is commonly found in rural and regional areas with the bacteria spread to humans from animals, mainly cattle, sheep and goats. Most cases are asymptomatic, but in some the infection can lead to pneumonia, bone and joint infections, chronic Q fever, heart disease and debilitating chronic fatigue syndrome.
The study, published today in the Medical Journal of Australia, found that only 40 percent of people in groups recommended for vaccination knew about the Q fever vaccine, and only 10 percent of people in these high risk groups were vaccinated.
This is the first community based study in Australia designed to measure past exposure to Q fever and identify factors associated with exposure. The researchers sampled 2740 blood donors in metropolitan Sydney and Brisbane, and in non-metropolitan regions with high Q fever notification rates (Hunter New England in New South Wales, and Toowoomba in Queensland).
Lead author Associate Professor Heather Gidding from University of Sydney and the National Centre for Immunisation Research and Surveillance (NCIRS) said: “As expected, evidence of past exposure through Q fever antibodies was higher in non-metropolitan than metropolitan regions in both NSW and Queensland.
We estimate that 29 to 39 percent of people with symptomatic Q fever were not actually diagnosed with the disease.
“One in 20 rural Queensland donors showed evidence of past exposure, however one in 36 Sydney residents also had antibodies, indicating that exposure to Q fever is more common than expected.
“Adults who have regular contact with sheep, cattle or goats, abattoir workers, and those assisting with animal births had the highest levels of exposure and these groups are recommended to receive the Q fever vaccine.
“However, having lived in a rural area with no or rare contact with sheep, cattle or goats was itself associated with exposure, even after accounting for other exposures. Which means you are highly likely to be exposed to Q fever, not because you work with animals, but just because you live in a regional or rural area.
“We also estimate that 29 to 39 percent of people with symptomatic Q fever were not actually diagnosed with the disease.”
Co-author Associate Professor Nicholas Wood from University of Sydney and NCIRS said: “Awareness and access to Q fever vaccine needs to be improved – we need to increase vaccination rates for all people living in rural and regional areas.
“With only 40 percent of people in groups recommended for vaccination knowing about the Q fever vaccine, and only 10 percent vaccinated, there are a lot of people at risk of catching the disease.
We found that most rural donors were exposed to multiple risk factors.
“Raising awareness about Q fever and the vaccine in rural communities and amongst health care workers will help improve uptake of what is a highly effective vaccine.
“A new online training module for rural general practitioners has recently been developed by the Communicable Diseases Branch, Health Protection New South Wales through the Australian College of Rural and Remote Medicine and should improve awareness of the vaccine as well as improve general practitioners’ knowledge about Q fever and how to diagnose it.
“We recommend more detailed studies in rural communities to identify reasons for their increased risk. But given we found that most rural donors were exposed to multiple risk factors, it would be a good idea for people to discuss with their GP their own need for the Q fever vaccine,” he said.
Q fever is caused by the highly infectious bacterium Coxiella burnetii, which has an almost world-wide distribution. C burnetiiinfects both wild and domestic animals and their ticks, and humans are exposed via the inhalation of infected droplets or dust.
Most infections (20-80 percent) are asymptomatic but when acute illness does occur the symptoms are non-specific, ranging from a self-limiting influenza-like illness, to more severe symptoms of pneumonia, hepatitis, heart and bone conditions.
Chronic Q fever, which may occur years after infection, is most often characterised by endocarditis but may also include osteomyelitis and hepatitis. Approximately 10-15 percent of cases experience a protracted post Q fever fatigue syndrome.
In the past five years (2013-2018) there have been on average 517 cases reported annually. Studies indicate 40-50 percent of notified cases were hospitalised for a median of 4-6 days each. It is likely these figures are underestimated due to the asymptomatic and non-specific nature of acute infection.