Contagious Agalactia In Sheep And Goats: Current Perspectives

Abstract

Contagious agalactia (CA) is a disease caused equally by four Mycoplasma species, in single or mixed infections. Clinical signs are multiple, including mastitis, arthritis, keratoconjunctivitis, pneumonia, and septicemia, non-specific, and expressed differently depending whether sheep or goats are affected, on causative mycoplasmas as well as type of husbandry. CA has been reported worldwide and its geographic distribution maps to that of small ruminant breeding areas. However, as current diagnostic tests are expensive and difficult to implement, it is certainly underdiagnosed and prevalence data are only available for a few countries. CA control relies on vaccines, chemotherapy and good herd management practices. It requires long-term commitment but is often unsuccessful, with frequent clinical relapses. The persistence of the etiological agents, despite their overall susceptibility to antimicrobials, comes from their genetic plasticity and capacity to escape the host immune response. The existence of asymptomatic carriers and the numerous sources of infections contribute to rapid spread of the disease and complicate the control and prevention efforts. Here we review all these aspects in order to highlight recent progress made and identify gaps in knowledge or tools needed for better disease management. Discussion also underlines the detrimental effect of contagious agalactia on small ruminant welfare.

Keywords: contagious agalactia; diagnosis; disease prevention and control; epidemiology; mycoplasma; pathogenicity and infection course.

Figure 1

Distribution of contagious agalactia in 2014 and 2018 in Mediterranean countries according to OIE reporting. Notes: Reproduced with the kind authorisation of the World Organisation for Animal Health [OIE] www.oie.int. World Organisation for Animal Health (OIE).