The clinical picture in a dairy herd infected with  Coxiella burnetti  is complex, can be confused by other factors and is often subclinical. The subclinical picture alongside variations in shedding of the bacteria can make diagnosis a challenge. 

Abortion, Premature Calving, Stillbirth or Weak Newborn Calves.

The clinical signs above can all be caused by infection with Coxiella burnetii (the bacterium that causes Q Fever)⁹. A cow that has been exposed to the bacteria (seropositive) is 2.5 times more likely to have an abortion¹⁰.Q Fever has recently been diagnosed as a cause of multiple stillbirths from heifers on a UK farm, this was reported through the SRUC surveillance reports.

Metritis, endometritis and retained foetal membranes (placenta):

A cow that has been exposed to the bacteria (seropositive) is 1.5 times more likely to have retained foetal membranes¹⁰.

Herds with evidence of bacterial circulation (positive BM PCR) were 2.5 times more likely to have a high incidence of metritis/clinical endometritis¹¹.

Infertility: Infection may cause an increased calving to conception interval as well as increased early pregnancy loss¹².

When to consider Q Fever?

Herd clinical signs:

• Increased abortion, stillbirth or weak born calves
• Increased retained foetal membranes
• Increased metritis, endometritis or pyometra
• Fertility issues;
  • Extended calving to conception intervals
  • Increased returns to service
  • Poor pregnancy rate

It is important that other (more common) possible causes of the issue are investigated and ruled in or out for example

• Nutritional issues especially transition cow management
• Other infectious diseases such as BVD, IBR or Leptospirosis