An effective management strategy for the control of two lentiviruses in goat breedings

Abstract

Caprine Arthritis Encephalitis is an endemic disease in goat breedings, caused by viral strains belonging to the Small Ruminant Lentivirus group and characterized by a progressive chronic course. Its clinical signs are not immediately recognizable and can only be detected via costly serological tests. No vaccine is available. Two main strategies for fighting it are in common use. The "test-and-slaughter" approach, that selects infected goats and directly slaughters them, is expensive, time consuming and often leads to endemic low level persistence of the infection. Alternatively, newborns are removed from their mothers to be raised by healthy goats. After weaning they would rejoin their breeds, but then they could still be subject to horizontal contagion. In this study a mathematical model that considers the cocirculation of two different SRLV viral genotypes (B and E) is devised and analyzed, based on the key assumption of perfect cross-protection between the two genotypes' infections. Two strategic measures arise from its analysis, that are strongly recommended and whose implementation is encouraged: in the presence of both genotypes, the farmer should not isolate the newborns from their mothers but rather raise them with all the other animals. In the case of genotype-B-only affected farm, serological testing and mother-offspring separation should still be considered the best strategy for CAEV control. These strategies completely reverse the current removal policy and, in due conditions, would lead to disease eradication. These represent very reasonable and cheap measures for the eventual control of the epidemics.

Keywords: Caprine arthritis encephalitis; Control strategy; Mathematical model.