Q Fever: Risks in Lambing Season and at Other Birthing Times

Background

Q (standing for “Query”) fever, was so called originally because for many years its cause was unknown. It is now known to be an infection with the organism Coxiella burnetii. It is usually, but not always, caught by direct contact with farm animals, especially sheep, cattle and goats. Most cases are sporadic; outbreaks are unpredictable but do occur and are more likely to affect urban (i.e. non-immune) populations.

Amongst livestock animals, sheep, cattle and goats are most commonly infected although Q fever can also occur in domestic mammals and birds. Exposure to parturient cats is a recognised mode of transmission.

Q fever in sheep and other livestock

Infection in farm animals is usually asymptomatic, although there may be inflammation of the placenta, or an abortion. It is however uncommon as a diagnosis of abortion in sheep and cattle.

Human infections: Q fever in pregnancy

Q fever acquired during pregnancy is usually asymptomatic in the mother, however chronic infections may subsequently become apparent. Occasionally, acute Q fever in pregnancy, regardless of whether this is symptomatic or not, may result in an adverse effect on the foetus including prematurity, low birth weight, or abortion. Subsequent pregnancies may also be at risk due to the possibility of a chronic infection in the mother.

Q fever is an uncommon disease in the UK. No recent cases are known to have occured in a pregnant woman.

Transmission

Transmission of Q fever occurs primarily through inhalation of contaminated aerosols. The organism is robust and can survive in dust and animal litter for many weeks, and in dried blood for at least 6 months at room temperature. The most infectious animal materials are the fluids of birth and afterbirth, followed by blood, milk, urine and faeces. Such infectious materials can be either livestock or domestic animal related, including parturient sheep, goats, cattle and cats.

The infectious dose can be as low as a single organism. Humans can acquire Q fever by:

• Inhalation of aerosols from placental tissue or amniotic fluids, or from urine, faeces or the carcass of infected animals
• Contaminated bedding or litter (hay or straw) from infected animals
• Inhaling airborne particles from the environment (dust, soil, straw and wool)
• Contact with infected material through cuts or abrasions in the skin, or through the conjunctiva

Prevention

This is based upon restriction of access to potentially infected animals, and appropriate disposal of animal birth products.

Pregnant women should avoid close contact with sheep and lambs during the lambing season. As other livestock and domestic animals may also pose a hazard for Q fever, pregnant women should avoid exposure to cattle, goats, or cats, which are in the process of giving birth, or in the post-partum period

Last reviewed: 6 August 2009