The role of small mammals in the ecology of Coxiella burnetii in Spain

    IREC and CNM-ISCIII scientists discover that wild small mammals are relevant in the transmission of Coxiella burnetii, the bacterium that causes Q fever in humans and coccyellosis in animals.


    Animals are a reservoir for the bacteria that cause Q fever, known to science as Coxiella burnetii, but many also suffer the consequences of the infection. In addition, this disease can trigger severe cases of acute hepatitis and pneumonia In person. In some patients, Q fever can become chronic and cause chronic valve disease, endocarditis, hepatitis, or pneumonia, known as post-Q fever fatigue syndrome.

    Spain has been reporting 30% of all cases of Q fever in the European Economic Area since the disease became notifiable in 2015. On the other hand, in domestic animals, it is estimated that approximately 10% of abortions in sheep and goats in Spain may be caused by the bacteria that cause Q fever.

    Previous investigations of Research Group in Health and Biotechnology (SaBio) of the Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM) have already shown that wild animals, such as the deer (Cervus elaphus) or the wild rabbit (Oryctogalus cuniculus), can maintain genotypes of C. burnetii different from those that circulate in cattle and that these are relevant in the transmission of this bacterium at the wildlife-livestock-human interface..

    However, C. burnetii is capable of infecting a tremendously wide range of animals, but the knowledge of wild animals that may have a relevant role in the ecology of this bacterium is far from being desirable for prevent and control diseases caused by.

    En este sentido, the challenge is to access appropriate samples of different wild animals to identify what role they play in maintaining C. burnetii and what risks they pose to the occurrence of Q fever cases in humans and coccyellosis in cattle, as well as whether they carry new variants of the bacterium capable of causing more severe cases of disease than those caused by the more common variants in cattle and people.

    For this reason, the scientists of the SaBio Group and the Research Group in Game Resources and Wildlife Management of IREC, in this case in collaboration with researchers from the National Center for Microbiology of the Carlos III Health Institute (CNM-ISCIII), set out the objective of to analyze the degree of exposure of different species of small mammals to infection by C. burnetii ..

     

    Capture in a specimen of field mouse (Apodemus sylvaticus) for the analysis of infection by Coxiella burnetii.

    The results of this scientific study, which have been recently published in the journal Animals, show that almost 10% of the small mammals analyzed were infected by C. burnetii. The infection could be determined in peasant vole, field mouse, gray shrew and black rat.

    The peasant vole, a pest species in the northern sub-plateau and linked in other scientific studies to the direct and indirect transmission of tularemia to animals and people, showed the highest prevalence of infection with 11%. The study has also revealed that the peasant vole is capable of eliminating the bacteria and thereby transmitting it to other animals and people, since it can remain infective even under adverse environmental conditions in the form of spores. The bacterium could be genetically characterized in one of the infected peasant voles, turning out to be of the genotype of C. burnetii most widely distributed in Europe, Genotype II+, which is common in sheep and people.

     

    Map of the spatial distribution and prevalence of infection by Coxiella burnetii of different species of wild small mammals in Spain. The numbers of each point represent the number of positive animals compared to the total number of animals analyzed.

    One of the scientists behind this work was diagnosed with clinical Q fever after presenting symptoms of weakness and persistent fever one week after doing field work, specifically collecting samples of peasant vole. The researcher had no exposure to domestic animals for several weeks prior to developing symptoms, suggesting that the infection likely originated in the small mammals he was sampling.

    This suggests that the use of basic protection equipment in the capture of these small mammals, basically rubber or latex gloves, may not be enough to prevent transmission and it would be advisable to wear a mask and extreme hygiene protocols when handling these animals.

    The scientific publication of this research is available at: