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Brucellosis is a bacterial disease that often leads to joint pain (arthralgia), muscle pain (myalgia), fever, headache, and weakness. The bacterium can live inside animals and can be spread to people. Brucellosis is uncommon in the United States (around 100 cases per year are reported), but it can cause serious illness, especially in pregnant women, immunocompromised individuals, infants, and the elderly.

Brucellosis is reportable to the Iowa Department of Public Health by Iowa Administrative Code 641 IAC 1.


It can take anywhere from a few days to two months before an infected person starts to see symptoms of a brucella infection. When symptoms do show up, they often resemble the flu and include:

  • Fever - may be intermittent or irregular
  • Headache
  • Chills
  • Sweats
  • Weakness
  • Depression
  • Joint, muscle and back pain

In some cases, symptoms may disappear for months and then return. Even after treatment, symptoms persist in some affected individuals for months to years.


Brucellosis is caused by the bacterium brucella. It normally infects people by spreading from one of its many animal reservoirs. The most common animal reservoirs are cattle, pigs, goats, sheep, and rarely dogs. This disease has been eliminated from domestic animal populations in the United States. However, it periodically infects this population after exposure to wildlife, such as wild pigs. The bacteria can spread from animals to people in three main ways:

  • Direct contact. Transmission occurs through direct contact (breaks in the skin or mucosal surfaces) with infected animal tissue, blood, urine, vaginal excretions, aborted fetuses, or placentas.
  • Unpasteurized dairy products. Transmission can also occur from the ingestion of raw milk and dairy products (unpasteurized) that came from an infected animal,
  • Inhalation. When individuals breathe in bacteria that are in the air.

Person-to-person transmission is rare, but has been documented.

Risk Factors

Although brucellosis is rare in the United States, those most at risk for infection are people who have the potential to come into contact with infected animals. Examples include veterinarians, animal clinic employees, wildlife officers, and farm workers. Individuals who drink raw milk or eat unpasteurized dairy products are also at higher risk of infection.


Many measures can be taken to prevent brucellosis infection:

  • All people who regularly interact with animals or animal carcasses should take the appropriate precautions such as wearing gloves and maintaining a well-ventilated workspace.
  • Consumption of all dairy products that are unpasteurized should be avoided.
  • Diseased animals should be identified and controlled through vaccines or slaughter of infected herds.


Treatment for brucellosis consists of appropriate antibiotic treatment that is initiated by a health care provider.


Brucellosis infection is rare in Iowa with only one or two cases per year.  Three cases were reported in 2020 and no cases were reported in 2021.  

For more detailed information and statistics on all notifiable diseases, please see our current annual report.

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