Q fever and udder health

Coxiella burnetii, the agent of Q fever, causes reproductive disorders in ruminants. The most serious is the ASPW syndrome (Abortion, Stillbirth, Premature delivery, Weak offspring). In cattle, other symptoms are also known, such as retained placenta, endometritis and fertility disorders (Gisbert et al., 2024).

As early as 1956, a study involving a dairy cow experimentally infected with C. burnetii showed that during the acute phase of the disease, milk production fell. This could be explained by hyperthermia. However, after clinical recovery, the animal's production did not return to its pre-infection level. (Zotov et al., 1956).

Since then, other studies have confirmed the link between Q fever and mammary infections or milk yield in cattle, goats and sheep.

Q fever and intra-mammary infections

The bacterium is shed in milk by cows, goats and, to a lesser extent, ewes. It is therefore common to get a positive PCR result from the milk of a cow infected with Q fever. One study showed a significant correlation (p=0.02) at quarter level between the presence of C. burnetii DNA and the incidence of sub-clinical mastitis (Barlow et al., 2008). Other studies showed that seropositive cows were more likely to have a mastitis, a mammary oedema (Paul et al., 2012) or a high Somatic Cell Count (Khatun et al., 2022). In the same way, in another trial, cows with a history of clinical mastitis were 2.35 times more likely to be positive for C. burnetii than healthy females (p=0.0006; Dhaka et al., 2020)

In addition to these studies establishing a correlation between clinical or sub-clinical mastitis and C. burnetii infection of the animals, massive episodes of Q fever related clinical mastitis have been described in dairy sheep flocks. The clinical picture showed hyperthermia, severe inflammation of the udder and a significant change in the appearance of the milk (odour and colour). Then, the milk production stopped. The mastitis progressed to the death of animals not treated with an antibiotic in time (Martinov, 2007).

Q fever and milk yield

Data published over the last few years has highlighted the impact of Q fever on milk production, in terms of both quantity and quality.

Firstly, in goats, a study showed that high shedder females had a 17% reduction in milk yield (p=0.02) compared to PCR negative animals (Canevari et al., 2018). On the other hand, in cattle, in an infected herd, it was shown that heifers infected at the start of lactation (seroconversion before 42 days of lactation and vaginal shedding of C. burnetii) had a significantly lower global fat content in milk over the entire lactation (305 days) than animals that remained seronegative. Although the differences were not significant, a similar trend was found for protein content and the global quantity of milk produced over 305 days of lactation (Table 1; Freick et al., 2016)

Table 1. Comparison of milk yield, milk fat and milk protein over 305 days of lactation between C. burnetii non-infected and infected heifers (adapted from Freick et al., 2016)

Key messages

Although the number of studies on the involvement of Coxiella burnetii in udder health remains low at present, the following points can be made:

• Coxiella burnetii can be an agent of clinical or sub-clinical mastitis.
• The deterioration in milk production, in terms of both quantity and quality, appears to be a consequence of Q fever in ruminants.
• Further studies in the three species would be useful to confirm these results.

References 

Barlow, J., Rauch, B., Welcome, F., Kim, S., Dubovi, E., & Schukken, Y. (2008). Association between Coxiella burnetii shedding in milk and subclinical mastitis in dairy cattle. Veterinary research, 39(3), 1.

Canevari, J. T., Firestone, S. M., Vincent, G., Campbell, A., Tan, T., Muleme, M., ... & Stevenson, M. A. (2018). The prevalence of Coxiella burnetii shedding in dairy goats at the time of parturition in an endemically infected enterprise and associated milk yield losses. BMC veterinary research, 14, 1-9.

Dhaka, P., Malik, S. V. S., Yadav, J. P., Kumar, M., Barbuddhe, S. B., & Rawool, D. B. (2020). Apparent prevalence and risk factors of coxiellosis (Q fever) among dairy herds in India. PloS one, 15(9), e0239260.

Freick, M., Enbergs, H., Walraph, J., Diller, R., Weber, J., & Konrath, A. (2017). Coxiella burnetii: Serological reactions and bacterial shedding in primiparous dairy cows in an endemically infected herd—impact on milk yield and fertility. Reproduction in Domestic Animals, 52(1), 160-169.

Gisbert, P., Garcia-Ispierto, I., Quintela, L. A., & Guatteo, R. (2024). Coxiella burnetii and reproductive disorders in cattle: a systematic review. Animals, 14(9), 1313.

Khatun, M., García, S. C., Thomson, P. C., Parker, A. M., Bruckmaier, R. M., & Bosward, K. L. (2022). Effect of Coxiella burnetii infection on milk constituents and cow behaviour. Animal Production Science.

Martinov, S. (2007). Studies on mastites in sheep, caused by Coxiella burnetii. Biotechnology & Biotechnological Equipment, 21(4), 484-490.

Paul, S., Agger, J. F., Markussen, B., Christoffersen, A. B., & Agerholm, J. S. (2012). Factors associated with Coxiella burnetii antibody positivity in Danish dairy cows. Preventive veterinary medicine, 107(1-2), 57-64.

Zotov, A. P., Chumakov, M. P., Markov, A. A., Stepanova, N. I., & Petrov, A. N. (1956). Experimental reproduction of Q fever and serological investigations. Veterinariya. 1956; 1956:44–53