Is there a query over Q fever in your herd?

Primarily affecting reproductive performance in cattle, Q fever is thought to be endemic in GB dairy farms, with studies showing positive bulk milk samples ranging from 70 per cent polymerase chain reaction (PCR) positive in south-west England to 80 per cent enzyme-linked immunosorbent assay (ELISA) positive results across 255 UK herds.

Renzo Di Florio, veterinary advisor at Ceva Animal Health, says farmers should ask their vet to investigate Q fever if cows in their herd are experiencing high levels of metritis and endometritis, unexplained abortions or stillbirths or if there is unexplained poor fertility performance such as repeat breeding, higher calving to conception rate and embryo loss.

He estimates that for a 100-cow herd, the disease could cost more than £7,000 a year, yet it is frequently overlooked as other infertility causes are often investigated first.

Cause

The disease, which is caused by the bacterium Coxiella burnettii, is also zoonotic, which makes it a health risk to those in contact with infected animals, including farmers, farming families, vets and abattoir workers.

Mr Di Florio says: “Diagnosing Q fever can be challenging as infected dairy cattle generally do not display symptoms, however they include severe hyperthermia and rapid pneumonia in the acute phase with spontaneous recovery over seven days.

“In the chronic phase, Q fever affects reproductive performance in cattle and presents a serious threat to productivity. Symptoms include infertility, metritis, retained placenta, abortion, stillbirth and weak newborns.

“Infection may cause an increased calving to conception interval, as well as increased early pregnancy loss.”

He says that infection is generally through inhalation of aerosols and dust particles contaminated with the bacterium.

“The highest excretion level is observed in birth products such as foetal membranes, amniotic fluids and placenta, at parturition or abortion. However, other frequent routes of excretion are vaginal mucus, milk and faeces.

“Coxiella burnetti is highly resistant in the environment and can be transported by the wind for up to 11 miles, so slurry spreading on windy days should be avoided. The bacterium can also live for five months in soil and up to two years at -20degC and it thrives in dry environments. Rain and wet conditions can stop it spreading so easily.”

But Mr Di Florio says climate change means that Q fever may become more of a risk in the future and it has the potential to have a significant impact on both livestock health and production and human health.

He says diagnostic tests may include PCR in the bulk milk tank and ELISA blood tests.

“If there is a series of abortions in a herd, PCR on vaginal samples on at least two aborted dams should be taken. It is essential that the sampling is done within seven days following the abortion and is sent without delay to a veterinary diagnostic centre. The placenta and stomach content of aborted calves can also be sent as sample materials for investigation.”

There is also a vaccine available that significantly decreases the excretion of Coxiella burnetti. It can be safely used in pregnant animals and can help to minimise shedding from infected cows and protect naive animals.

Underestimated

Mr Di Florio says: “Q fever has been historically underestimated in UK dairy herds, however it is highly prevalent in the UK. It can survive for a long time in the environment, making the disease a significant problem and a threat to human health.

“It is advisable that farmers speak to their vets for advice about Q fever if they have any fertility issues or unexplained foetal losses at any stage of pregnancy in their herds to help protect both their health and the health and productivity of their cattle.”

Q fever control

Q FEVER is controlled by combining biosecurity and vaccination.

Biosecurity measures can help to reduce or prevent exposure to contaminated aerosols and minimise environmental contamination and can include:

■ A strict hygiene required during calving

■ Avoid spreading manure, especially in certain weather conditions (strong winds)

■ Remove and destroy the placenta and aborted foetus and clean the calving area

■ Avoid disinfecting with high-pressure sprays (aerosols) and check to make sure that the disinfectant being used is effective on the bacterium