Epidemiological study of the main infectious abortifacient diseases

In cattle,abortions deserve particularattention because oftheir heavy economicand hygienicimpact.

The aim of the present work is to carry out an epidemiological study of abortion frequencies in dairy cows during the 2022-2023 agricultural season inMorocco’s main dairy basins, namely the Loukkos, Gharb, Fès, Chaouia, Doukkala, Tadla, Souss Massaand Laâyouneregions

The epidemiologicalsurvey covered 77 farms with a total of 33,463 head ofadult female cattle. The study also included serological investigations into the main infectious abortifacient diseases, particularly brucellosis (Brucella sp.), Q fever (Coxiella burnetii), leptospirosis (Leptospirahardjo), salmonellosis (Salmonella dublin), neosporosis (Neospora caninum),and bovine Herpes virus 4 infection.

The serological survey covered a total of 535 randomly selected adult females of dairy breeds of different ages. Serological screening for brucellosis was carried out using the Rose Bengal Test, while serological screening for the other five infections was carried out using an indirect ELISAtest. For Q fever, in addition to serologicalanalysis, biomolecular PCR screeningwas carried out on bulk tank milk (BTM). This involved 72 samples of BTM from57 farms and 11 collection centers representing between 18 and 43 small farmers with a total of 1600 lactating cows. Four largefarms had two tanks.

The survey data revealed an overall abortion frequency of 14.2% for the 2022-2023 year. Abortion frequencies varied from region to region, ranging from2.1%in the Fezregion to 17.6%in the Loukkosand Gharb region. Theaverageintra-farmabortion rate was 5.4%.

Serological analyses showed that all the abortifacient agents investigated were present in the 7 regions where investigations were carried out. BoHV-4, Neosporosis, Q fever and leptospirosis infection showed seroprevalence levels of 59%, 56%, 31% and 27% respectively. Overall seroprevalence of brucellosis was 3.4%, particularly in the Loukkos, Gharb, Chaouia and Doukkala regions. The overall seroprevalence of salmonellosis at animal level was 3.6%, with the absence of infection in the Fes and Laâyoune regions. Neosporosis, BoHV-4, Q fever, leptospirosis, salmonellosisand Brucellosis werefound in 91%, 81%, 63%, 44%, 13% and 7,8% offarms respectively. At herd level, prevalences were 55%for BoHV-4, 48%for neosporosis, 24%for Q fever, 16%for leptospirosis, 7.8%for brucellosisand 3%for salmonellosis.

Among cowsaborted in the 2022-2023 campaign, seroprevalencerates were 59%for BoHV-4, 44%for neosporosis, 22%for Q fever, 15%for leptospirosis, 7% for salmonellosis and 3.7% for brucellosis. It should be noted that 22% ofcows were found to be seronegative forall infectious agents.

Biomolecular analysis of BTM revealed that 49% of samples were positive for the Q fever agent. Only one collection center out of 11 was positive. This shows that the bacteriumisactively circulating in almost one herd in two mostly inmediumand large dairy farms. Furthermore, 36% of ELISA-positivefarms were PCR-negative,and only one ELISA-negativefarmwas PCR-positive.

Based on the results ofthis study, it is recommended thata bovine abortion control programshould be implemented in Morocco, based on health surveillance,accuratelaboratory diagnosisand medical prophylaxis

Epidemiological study of the main infectious abortifacient diseases in Morocco.