Pregnant women in lambing season: advice

Listeriosis

Listeriosis is a disease caused by the bacterium Listeria monocytogenes. This disease can cause serious disease in the unborn or newborn child. The disease may be transmitted by contact with infected animals or ingestion of contaminated food.

Effect on human pregnancy

Infection may cause abortion or premature birth. Infection of the baby in the womb or during delivery may lead to septicaemia and meningitis with a 50 to 100% mortality.

Infection in the newborn may take the form of disseminated granulomatous disease, involving many organs including respiratory tract, eyes and nervous system.

Symptoms

Infection in pregnancy generally presents as a mild flu-like illness. 

How the infection is acquired

Infection is acquired by ingestion and most cases are probably the result of consumption of contaminated food. If contact with animals that are or have recently given birth is unavoidable, careful personal hygiene precautions and thorough washing of the hands after handling animals should prevent any possibility of infection.

How common is listeriosis

There are up to 25 cases of listeriosis in pregnancy reported annually in the UK, but it is not known how many of these, if any, are associated with direct contact with animals.

Diagnosis and treatment

The diagnosis may be made by culturing the organism from the mother's blood or faeces.

Listeria monocytogenes is susceptible to a number of antibiotics. 

Risk in subsequent pregnancies

Chronic or recurrent infection in expectant mothers is not associated with foetal infection. 

Effect on sheep

Abortion from 12 weeks of pregnancy onwards. There may be occasional deaths in ewes. Encephalitis due to listeria infection may also be seen, but is not generally associated with abortions.