Introduction/Causative Agent:
Recent reports have referred to the presence of Q fever on some sheep and goat farms in the United States. In most instances, this disease is found in only certain states and is associated with specific flocks and herds. This disease can also cause illness in people handling these sheep and goats. This would include sheep and goat dairy farmers, slaughterhouse operators, laboratory workers, and veterinarians. Q fever is caused by bacteria called Coxiella burnetii.Clinical Signs in Animals: In sheep and goats, Q fever is often seen in outbreaks rather than as individual cases. When sheep and goats become infected, Q fever causes them to abort (in late pregnancy) or have stillbirths. Situations of extreme stress (such as mixing of animals from different backgrounds and exposing animals to new surroundings) can cause the bacteria to be shed and make animals more vulnerable to infection. Other livestock (cattle, pigs, and horses) can also be infected, but rarely show any clinical signs.
Clinical Signs in Humans: Q fever in humans results in "flu-like" symptoms that include fever, headache, chills, sore muscles, loss of appetite, dry cough, chest pains, and sweating. These signs will vary depending upon whether the bacteria was inhaled or swallowed.
Disease Transmission in Animals: Animals that are infected with the bacteria shed the organism in placentas, birth fluids, colostrum, and milk. Other animals become infected when they inhale or ingest the bacteria. In areas where there are a lot of ticks, these arthropods can spread the disease. Grazing animals may also pick up the bacteria from contaminated pasture.
Disease Transmission in Humans: Humans usually get the disease by breathing in the bacteria. This most commonly occurs when contact is made with the birthing fluids of infected goats or sheep. This also happens when contaminated air is inhaled in a building where dusty bedding is disturbed.
In addition, people can become infected by swallowing the bacteria. This can happen by drinking contaminated raw milk or by not properly washing hands after handling contaminated material (placenta, aborted fetus, and afterbirth).
Diagnosis: Q fever can be diagnosed at a laboratory by identifying the Coxiella organism in placental tissues and fluids. This means that if abortions occur that are thought to be associated with Q fever, the fetus and placenta should be sent to an appropriate laboratory equipped to diagnose this disease. Animals that have the infection can also be identified by taking blood samples and performing various serologic tests (enzyme-linked immunosorbent assays and titers).
Treatment: If an outbreak of Q fever is diagnosed, each aborting animal and animals that are still pregnant should be treated with tetracycline. All aborted fetuses and placentas should be burned, and any affected animal should be isolated from the rest of the flock/herd.
Prevention: If possible, it is best to require that testing be done on all new animals before they are purchased to minimize the chances that the animals carry Q fever. Testing should also be done for many other diseases as well before purchasing new animals. Once purchased, the animals can be kept in isolation upon arrival to see whether they show signs of any illness that might affect other animals in the flock/herd. Many producers keep closed herds to help minimize the entry of disease. See page B240 for additional details on flock/herd management.
Humans that are in close association with sheep and goats during and after the birthing process should use filter masks and gloves. This is particularly important if there are any unidentified abortion problems in the flock or herd. Regular washing of clothes, boots, and hands also decreases the risk of disease. Many livestock operations keep their premises closed off to the general public. This reduces the chances of having any diseases brought onto the farm from boots, clothing, and even vehicles. This is what is referred to as biosecurity and is promoted broadly throughout the livestock industry. See page B76 for additional information on biosecurity.
The normal precautions that are taken for the handling of food products from animal sources (i.e. meat and milk) would also apply. These include cooking or pasteurizing the raw product, proper cleaning of surfaces that come into contact with raw product, and regular washing of hands.