Q fever and vaccination: quantifying the benefits

On January 16, the Q fever committee offered a webinar on the benefits of vaccination against this disease. The results of numerous studies show that it significantly reduces the incidence of Q fever in herds, down to only 1 to 3%, and that it can generate up to €12,000 in net profit per 100 cows.

The impact of Q fever on herds no longer needs to be proven. It is the second cause of infectious abortion in cattle, according to the Q Fever committee, which brings together veterinarians, breeders and, more generally, livestock professionals. Therefore, this committee organized a webinar on January 16 to discuss vaccination and its benefits, in the fight against this little-known zoonosis.

“In addition to miscarriages, Q fever also causes stillbirths in calves, delivery of weak animals, retained placenta and reproductive disorders”adds Raphaël Guatteo, veterinarian, professor of bovine medicine at Oniris and member of the Q fever committee.
He cites a study of nearly 5,000 cows in the early 2010s, which further shows that cases of retained placenta are multiplied by 1.5 in Q fever positive cows. Fertilization increases by 10 to 20 days.

Evaluate the economic consequences

Quantifying the economic impact of Q fever requires considering the costs themselves (treatments, veterinary visits), but also the losses: stillborn calf, unproduced milk… Figures that vary according to the type of farming and the circumstances.
The cost of an abortion, for example, is estimated to be between €400 and €800 for a bovine. It depends on the type of production, when it occurs, on the genetic value of the animal. It also changes whether or not the animal initiates nursing and whether it should be killed afterwards.
Treatment of a retained placenta costs only 5 to 10 €. But it causes a loss of about 300 liters of milk, to which is added the lengthening of the calving-AI/fertilization interval.

Infertility, an invisible cost

“The losses are generally double the costs generated by the disease. The latter must therefore be multiplied by three to estimate the real economic impact”explains Raphaël Guatteo.
He points out that the most important consequences concern infertility caused by Q fever. Indeed, breeding studies show a large number of late heat returns, which are probably early abortions. In addition to an extension of the birth-birth interval, the cost of which is estimated at 5 euros per day.

An effective vaccination

“To remedy this situation, there is a vaccine against Q fever. But its implementation must still be justified by economic viability”explains Didier Raboisson, professor at the veterinary school of Toulouse.
He cites a three-year study of groups of 100 cows. In each of the groups, 20 to 40 cows are positive for Q fever. Some groups are fully vaccinated and some are not, the latter serving as controls. Vaccinated flocks receive a booster and primary vaccination of young animals each year.
The results show that vaccination strongly reduces the rate of infected animals. By the end of the third year, the rates of 20 and 40% had dropped to 1.2 and 2.3%, respectively, while they were stable in the control groups.

For farm animals, the economic benefit of vaccination is evaluated as follows: losses caused by disease in unvaccinated flocks – persistent losses in vaccinated flocks – costs of vaccination.

The results show a net profit per 100 cows of €3,214 when the initial infected rate is 20% and €11,937 when it is 40%. So there is profitability.

Limit transmission

Didier Raboisson underlines the fact that vaccination also has the advantage of reducing the excretion of the bacterium Coxiella burnetiithe cause of the disease. This greatly reduces the chances of transmission between herds, as well as to humans. The risk is therefore also reduced for the farmer. In fact, present in all ruminants and sometimes in domestic animals, Q fever is transmissible to humans. Highly contagious, it is asymptomatic in 90% of cases. 10% of infected people develop flu-like symptoms, sometimes body aches or heart disease. In pregnant women, it can cause miscarriage or premature birth. Fatal cases are rare.

Emmanuel Bordone

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Learn more about Q fever and find the webinar

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