Risk factors responsible for the appearance of individual clinical signs in small ruminants in northern Cameroon

Abstract

A survey was conducted in north and far-north provinces of Cameroon to determine the risk factors responsible for the appearance of clinical signs in small ruminants. Eight flocks, with a total of 141 animals, were visited weekly for 21 months by field agents who noted the appearance of individual clinical signs. The animals were weighed monthly and their faeces were collected for coproscopic examination. At the same time, their sera were tested against the following microbes: Mycoplasma mycoides subsp. mycoides LC, M. capricolum subsp. capricolum subsp. nove, M. agalactiae, M. capricolum subsp. capripneumoniae, Capripoxvirus and peste des petits ruminants (PPR) virus. The independent variables were province, season, species, sex, age class, presence of external parasites, infestation level by intestinal parasites and seroconversions. The survey emphasized the influence of species and season on nasal discharges (more frequent for sheep and in the cold dry season). The prevalence of contagious agalactia syndrome was higher for animals more than one year old and during the cold dry season; furthermore, it was strongly correlated with mycoplasma seroconversion. The seroconversion against PPR was concomitant with that against Capripoxvirus. Slow growth was associated with strongylosis infestation, the presence of external parasites and the PPR-Capripoxvirus seroconversion. Considering the high cost of vermifuges and insecticides, only a vaccination campaign appears to be suitable. Long-term control measures against parasitical diseases should focus on livestock practices. Hence, it is recommended to compare the productivity of flocks vaccinated with a mixed PPR-Capripoxvirus vaccine, and reared under different livestock conditions.