Managing Q fever outbreaks this spring

As warmer weather approaches, many livestock producers across the state are set to begin preparations for birthing season for several ruminant species. This year, the Texas A&M Veterinary Medical Diagnostic Laboratory, TVMDL, encourages producers to be aware of Q fever and add an extra layer of precaution to their preparations.

“It can affect a wide range of animal species, including livestock like cattle, sheep and goats,” said Terry Hensley, DVM, TVMDL assistant agency director and Texas A&M AgriLife Extension Service veterinarian, Bryan-College Station. “When we notice a reproductive loss, Q fever rises in the list as a potential cause.”

What is Q fever?

Q fever is a highly contagious zoonotic disease caused by the bacteria Coxiella burnetii. Humans who are infected with Q fever usually have no symptoms or mild ones, but they may have flu-like symptoms. Infected animals may experience reproductive disorders.

C. burnetii is found in an infected animal’s bodily fluids and excretions, such as placental tissues, amniotic fluid, urine, feces and milk. For animals, the main signs of infection include abortion, infertility, fever, lethargy and loss of appetite.

“It can spread to humans by inhalation from contaminated dust particles in a dusty environment,” Hensley said. “Or it can be spread through exposure to birthing fluids, feces, urine or even wool from an infected animal.”

Considering these modes of transmission, maintaining sanitation and protection are recommended when handling and managing livestock, especially during the birthing process.

Face and eye protection might also be considered in some handling scenarios and environments.

Detecting C. burnetii

Identifying C. burnetii through a bacterial culture can be very difficult. TVMDL offers a polymerase chain reaction, PCR, test for detecting the pathogen.

This test is highly sensitive and uses a specific technique to amplify the DNA of the bacterium to detect small traces of the pathogen in a sample.

Recommended samples and specimens collected for assays include fetal tissue, placental tissues, vaginal swabs and milk samples.

“It’s essential to follow strict biosecurity and personal hygiene measures,” Hensley said. “At least make sure to wear gloves when collecting the samples.”

If a favorable sample for PCR cannot be provided, blood samples for serological tests can be used to detect antibodies against C. burnetii, which may indicate prior exposure or chronic infection.

Interpreting results

Typically, diagnosing Q fever involves a combination of clinical observation, laboratory testing and consultation with a veterinarian. Test results should be interpreted considering the clinical history and epidemiological context.

“We’re going to have to do diagnostic testing to get a handle on whether it truly is a C. burnetii problem or something else,” Hensley said. “In abortions, there may be other clinical things going on. There may be Q fever present in the animal, but it may not be the cause of the abortion.”

Furthermore, the limitations of PCR tests should also be considered during interpretation. A positive PCR result confirms the presence of C. burnetii nucleic acid in a sample. It does not necessarily indicate an active infection. The test may detect dead bacteria not contributing to the animal’s current clinical status.

Defense against Q fever

Above all, veterinarians and livestock producers should consider the zoonotic potential of Q fever and uphold biosecurity and personal hygiene when handling potentially infected animals and collecting samples. TVMDL contributes to effective Q fever outbreak management by offering high-quality testing options and help with a comprehensive interpretation of the lab results.

Livestock producers who suspect Q fever should consult their veterinarian to determine other possible disease differentials, sample collection and treatment options.

For more information about Q fever testing at TVMDL, visit https://tvmdl.tamu.edu or call the College Station lab at 888-646-5623.