Sheep and goat pox (SGP) is a notifiable viral disease of small ruminants. Animals infect each other through direct contact and through manure, saliva, nasal secretions, skin injuries and dander. Wageningen Bioveterinary Research (WBVR) conducts research into this disease.
Notifiable means that suspicions of sheep pox and goat pox infection must be reported to the NVWA. SGP is a “Categorie A” disease (Animal Health Law). The disease is caused by the SGP virus (SGPV, family of Poxviridae, genus Capripox virus).
In adult animals, up to 80% of a flock can become ill and up to 50% can die. In young animals, these percentages are even higher, up to 100% sick and 95% mortality. Morbidity and mortality are the highest for young animals and lactating ewes/goats. In areas where the disease has not occurred before, such as the Netherlands, all animals will in principle become ill and death will also occur. Secondary infections can cause increased mortality. In animals with little or no resistance, the symptoms can be very serious. In addition to sheep and goats, cattle can also be infected by SGPV.
Sheep and goat pox has never been reported in the Netherlands. The Netherlands is therefore historically free of sheep pox and goat pox.
The severity of disease can vary and strongly depends on the virulence of the virus, the age of the animals and the natural resistance. The disease usually begins with fever and loss of appetite after an incubation period of 12 days to a maximum of 21 days. After the first symptoms, the animals can develop nodules or pox. Nodules start as red spots, especially in areas where there is no wool or hair. These red spots develop into nodules or lumps, pustules and finally into thick crusts, which can later peel off. The animals also often have eye and udder infections. Finally, the lungs can also be affected.
In cattle, the disease runs completely subclinical, that is without obvious clinical signs.
Sheep and goat pox is endemic to Africa, the Middle East and Asia. The disease also occasionally occurs in Europe. In 1998 and 2000, there were outbreaks in Greece that were probably caused by illegal imports of sheep. In January 2007, SGP was reported on a Greek island. There is no guarantee that the disease will not be introduced in Europe.
Animals infect each other via direct contact and via manure, saliva, nasal discharge, skin injuries and via dander. In dry skin parts, the virus can last up to six weeks. Biting insects, for example the stable fly Stomyxos calcitrans, are also known spreaders of SGPV. Contaminated materials such as vehicles, injection needle instruments can also spread SGPV. The virus is very stable outside the body and indirect contamination as a result of badly cleaned livestock trucks is therefore quite possible. Therefore, the virus can spread over short distances via direct contact and biting insects, and over longer distances via clothing or transport equipment and (unprocessed wool from) infected animals. People can therefore spread the virus, including through clothing, shoes and hands. The virus is harmless to humans.
Sheep and goat pox is a notifiable animal disease. Wageningen Bioveterinary Research (WBVR) is the national reference laboratory for sheep and goat pox and has ISO-certified tests to diagnose suspected SGP.
Antibodies to SGPV after infection from vaccination can be detected by the ELISA, the ImmunoPeroxidase Monolayer Assay (IPMA) or the serum neutralization test (SNT). The ELISA is the first choice for detecting antibodies. The IPMA is more sensitive than the ELISA and particularly suitable for serological confirmation of recent SGPV infections. The SNT can confirm positive ELISA of IPMA results, although the SNT is less sensitive. Clotted blood (serum blood) is used in these serological tests.
The virus can be detected by the PCR test for the Capripox viruses, SGPV and the lumpy skin disease virus, of which the latter has been recorded exclusively in cattle. Positive results of material from small ruminants is therefore SGPV. This can also be confirmed with the PCR test specific for SGPV. Nose - and eye discharges and skin biopsies of nodules or lymph nodes are very suitable for detecting virus. Whole blood (EDTA blood) is less suitable. Samples of blood or organs must be transported on ice (not frozen).
Live attenuated (LAV; live attenuated vaccine) SGPV is not a DIVA vaccine and is not registered in Europe. LAV for sheep pox and goat pox is not available in the Netherlands. The European Commission can authorize limited vaccinations to control an outbreak. Vaccination can have negative consequences for exports.