Q fever in goats is a bacterial infection caused by Coxiella burnetii, an extremely hardy organism that primarily targets the reproductive system. Most infected goats show no visible signs of illness, which makes the disease deceptive. It becomes apparent when pregnant does abort late in gestation, sometimes in clusters, and the real concern extends beyond the herd: Q fever is a serious zoonotic disease, meaning it readily spreads to people who handle infected animals or even breathe contaminated dust.
What Causes Q Fever
The bacterium behind Q fever, Coxiella burnetii, is classified as a category B biological threat agent because of its remarkable ability to survive outside a living host. It exists in two forms, and its smaller, dormant form has a dense, heavily cross-linked outer shell that resists heat, drying, chemicals, and mechanical stress. Viable bacteria have been recovered after several years in dust, over seven months on wool at room temperature, five months in soil, and more than a month in fresh meat. This environmental toughness means a contaminated barn or pasture can remain infectious long after the source animal has moved on.
Inside the goat, the bacterium is an obligate intracellular pathogen, meaning it can only reproduce inside living cells. It specifically targets immune cells and, critically, the trophoblasts of the placenta in pregnant does. As pregnancy progresses, the bacteria multiply at an accelerating rate in placental tissue. C. burnetii also colonizes mammary gland tissue, where low oxygen conditions during late gestation and early lactation appear to impair the immune system’s ability to clear the infection. This creates a long-term niche for the bacteria, which is why infected goats can shed the organism in milk intermittently for weeks or longer.
How Goats Spread It
Infected goats shed C. burnetii through three main routes: vaginal mucus, feces, and milk. The heaviest contamination happens during kidding. Birth products like placental tissue and amniotic fluid contain enormous bacterial loads, and when this material dries, it becomes airborne dust that can travel long distances on the wind. Even apparently healthy goats that never aborted can shed bacteria in vaginal mucus and feces, silently contaminating the environment.
Fecal and vaginal discharges have the greatest impact on environmental contamination, particularly during kidding season and through effluent management practices. After an abortion episode in a herd, the proportion of goats actively shedding bacteria remains high enough to pose a significant exposure risk to other herds and to people.
Signs of Infection in Goats
The frustrating reality of Q fever is that most infected goats look completely normal. Adult goats rarely develop any visible illness. The disease reveals itself through reproductive failure: late-term abortions, stillbirths, retained placentas, weak kids that fail to thrive, and reduced fertility. In an outbreak, anywhere from 5% to 90% of pregnant does in a herd may abort. One Texas diagnostic case documented four does on the same property aborting within 48 hours, none of which showed any other clinical signs.
Aborted fetuses typically appear normal on external examination and may be either fresh or partially decomposed. The placenta, however, often shows inflammation (placentitis) that can be identified during veterinary examination. Because the signs mimic other causes of reproductive loss in goats, including chlamydiosis and toxoplasmosis, laboratory testing is essential for a definitive diagnosis.
How Q Fever Is Diagnosed
Veterinarians use two main approaches to confirm Q fever. Blood testing through ELISA (enzyme-linked immunosorbent assay) detects antibodies against C. burnetii and is the standard screening tool for herds. Several commercial ELISA kits are available, with sensitivities around 90 to 94% and specificities between 77 and 89% when properly calibrated for goat samples. A positive antibody result tells you the goat has been exposed but doesn’t necessarily mean it’s currently shedding bacteria.
For direct confirmation, PCR testing on abortion material, vaginal swabs, milk, or fecal samples can detect the bacterium’s genetic material. This is particularly useful during an active abortion storm, when placental tissue provides the strongest diagnostic sample. Growing the organism in culture is possible but difficult, time-consuming, and typically reserved for research or confirmation in specialized laboratories.
How Common It Is
Q fever in goats is a global problem. A large-scale meta-analysis of seroprevalence studies found that roughly 23% of goats worldwide test positive for C. burnetii antibodies. Regional variation is dramatic: seroprevalence in North American goats averages about 6%, while in South America (driven largely by data from Brazil) it reaches 55%. Europe and Africa fall in between at approximately 25% each. These numbers reflect exposure history across populations, and actual shedding rates during any given period will be lower, but they underscore how widespread the bacterium is in goat herds around the world.
The Risk to People
Q fever is one of the most important zoonotic risks associated with goat farming. People become infected primarily by inhaling dust contaminated with dried birth products, feces, urine, or milk from infected animals. The infectious dose is extremely low, potentially as few as one to ten organisms. Outbreaks in goat herds have been directly linked to clusters of human Q fever cases, sometimes affecting people living downwind of farms who never had direct animal contact.
Those at highest risk include veterinarians, dairy workers, livestock farmers, and anyone assisting with kidding. In people, acute Q fever typically causes high fever, severe headache, and fatigue. A small percentage develop chronic infection that can affect the heart valves. The CDC recommends avoiding contact with animals during birthing and never consuming raw milk or raw milk products as basic precautions.
Vaccination
Coxevac, an inactivated vaccine manufactured in France, is currently the only Q fever vaccine available for goats. Licensed in Europe since 2010, it’s approved for goats from three months of age, given as two subcutaneous injections three weeks apart with a yearly booster. In experimental challenge studies, vaccinated goats had a 6% abortion rate compared to 75% in unvaccinated, infected goats. None of the vaccinated goats shed bacteria in milk, while 100% of unvaccinated infected goats did. Vaginal shedding lasted an average of just 1.5 days in vaccinated animals, and the bacterial load in placentas dropped by a factor of roughly one million compared to unvaccinated goats.
Vaccination works best as prevention rather than treatment. Goats vaccinated before exposure benefit the most. Mathematical modeling suggests that vaccination programs need to run for five to eight years to effectively control Q fever within an infected herd, but the approach is considered cost-effective when weighed against the losses from abortion storms and the public health consequences. Coxevac is not available in all countries, so access depends on local regulatory approvals.
On-Farm Prevention and Cleanup
Because C. burnetii is so environmentally persistent, biosecurity during kidding season is the most important line of defense. Kidding areas should be isolated from the rest of the herd and from public access. Placentas, aborted material, and soiled bedding need to be removed and disposed of promptly rather than left to dry and become airborne. Composting or burial is preferred over spreading contaminated manure on fields.
Disinfection is challenging. Standard bleach solutions, formalin, and Lysol have been found ineffective against C. burnetii. Effective options include 70% ethanol and Virkon S at 1 to 2% concentration, both requiring at least 30 minutes of contact time. The limited options for chemical disinfection reinforce why preventing environmental contamination in the first place, through prompt removal of birth products and good manure management, matters more than trying to decontaminate after the fact.
New animals entering a herd should ideally be tested before introduction, and herds with a history of unexplained reproductive losses should pursue diagnostic workups that include Q fever screening. In regions where Coxevac is available, vaccinating replacement does before their first breeding season offers the strongest protection for both the herd and the people who work with them.