What should you know about what causes undulant fever?

Undulant fever is a description of fever that fluctuates, not the name of one germ. Brucellosis is caused by Brucella bacteria and may follow contact with infected animals, animal tissues, or unpasteurised dairy. Risk depends on the exposure, and the fever pattern cannot prove the cause.

Other illnesses can produce fever that changes over time. Respiratory conditions such as acute bronchitis, bronchiolitis, COVID-19, or croup may be relevant when cough or breathing symptoms occur. Cellulitis may be considered when fever accompanies a hot, painful, spreading area of skin.

Book a clinical assessment if fever repeatedly returns or follows a relevant food, animal, or travel exposure. Bring a clear timeline, including temperature readings, chills, sweats, pain, cough, rash, bowel changes, and medicines. The clinician may select blood tests or other investigations according to your symptoms and exposure.

Keep drinking fluids and rest while awaiting advice. Avoid unpasteurised dairy and direct contact with potentially infected animal materials until the situation is clearer. Do not use someone else's antibiotics.

Use emergency services for severe breathing difficulty, fainting, confusion, a stiff neck, severe headache, or repeated vomiting. Seek same-day advice for dehydration, a rapidly spreading skin infection, or fever in pregnancy, infancy, older age, or a person with impaired immunity.

Ask whether brucellosis fits your exposure history, which tests can distinguish causes, whether household precautions are needed, and which changes mean you should return urgently.