The porcine reproductive and respiratory syndrom :

The porcine reproductive and respiratory syndrom (PRRS) is due to a small ribonucleic acid virus, member of the Arteviridae family. This virus multiply in the alveolar macrophages of lungs, in tonsil macrophages or dendritic cells, in lymphatic nodes, in thymus, in spleen, in liver, in kidneys, in surrenals and in heart.

Two symptoms are mainly observed: reproduction troubles (late abortions, abnormal lengthening of the gestation period, high neonatal mortality, lower fertility) and respiratory troubles associated to loss of weight and hyperthermia.

The virus generally stays several years in a herd.

The problem of the clinical diagnosis is that no lesion or no sign is specific to PRRS. All the signs are characteristic but not able to differentiate. Only the laboratory can confirm or infirm the suspiscion.

Current methods used are viral isolation, antigenemy, serology or RT-PCR.

Only RT-PCR allows the virus detection in semen, this one being toxic for the cells.