Alberta Health Services research-ers have documented 39 cases of Q fever in humans over a 13 year period.
Q fever is caused by the bacteria coxiella burnettii.
In people, the symptoms are vague and non-specific, including fever, headache, pain, chills, vomiting and diarrhea. The bacteria are shed in the birth fluids, placenta, urine and feces of infected animals, which are not typically ill.
Inhalation is the most important route of infection in people. Contaminated dust can harbour the bacteria, which can survive for long periods in the environment. The disease was spread through contaminated milk before widespread pasteurization.
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Most human infections occur from contact with sheep, goats and cattle, although a wide range of animals can be infected, including bears, deer and mice and marine mammals such as seals, sea lions and porpoises.
“Q fever is one of those zoonotic diseases that hasn’t really been well-studied across North America,” said Dr. Christopher Sikora, medical officer of health with Alberta Health Services.
“Since it is a disease that Alberta had data on, we decided this was a good opportunity to look back in our cases over the past couple of decades and describe them.”
Dr. Kate Snedeker, who also works for Alberta Health Services, has an interest in zoonotic diseases, which led her to participate in the study.
“Part of my role as a surveillance epidemiologist is to see what is happening. I have access to the data, so I’m the number cruncher.”
Researchers found both surprising and expected results after examining their data on human cases.
“Our rate was more than twice what was going on in the U.S., so it was relatively high in comparison,” said Snedeker.
Most people diagnosed with Q fever had contact with farms with livestock, including cattle, sheep and goats. Cases tended to occur in areas with high livestock densities, but these areas also overlap with areas where most people live, which might lead to a misleading association. There were more cases in men than women.
Researchers found that most cases of Q fever were diagnosed in spring, which correlated with the calving, lambing and kidding season.
“That is what you would expect because the highest concentration of the bacteria is in the placenta,” said Snedeker.
Pregnant women and people with heart valve disease or immunosuppression should be especially cautious on farms and maintain high levels of hand hygiene, avoid dusty areas or eliminate contact altogether.
Farm workers should be aware of the symptoms and seek medical attention if they are concerned.
Because the symptoms are non-specific, it may be helpful to mention animal contact to the physician.
Patients suspected of Q fever can be tested to confirm the diagnosis. A positive case must be reported to Alberta Health.
Specialized public health staff conduct the investigations in Alberta. Specific questions about risk factors for Q fever would be asked and recorded.
“Within Alberta, there are diseases of interest that have to be reported to Public Health. Q fever is on that list, which is the reason why we are notified of all the lab-confirmed cases,” said Sikora.
“I’m reassured that our labs can identify Q fever and help direct appropriate treatment.”
A course of antibiotics and supportive care is standard treatment for the disease.
Prevalence among Alberta livestock is unknown and no studies are underway.
Based on the Alberta Health Services study, it is reasonable to speculate that Q fever is a risk to people with livestock contact across Western Canada.
However, it is still considered rare when compared with other infectious diseases.
The number of cases in Alberta seems high, but these are probably only the tip of the iceberg.
“There’s no major symptom that indicates you have Q fever. It’s not like chicken pox where you get a rash that’s quite obvious,” said Snedeker.
“There are probably more cases that we simply don’t know about.”
