The genus Pestivirus includes several viruses from the Flaviviridae family. These viruses are specialized for mammals. Pestiviruses infect cattle and pigs in particular, causing serious diseases in them, sometimes resulting in considerable economic damage.
What are pestiviruses?
Viruses of the genus Pestivirus, like all Flaviviridae, are single-stranded RNA viruses. Their viral envelope consists of the lipids of their host cell. The genetic material of the virus is stored in it. Viruses also replicate within the original host cell. For this purpose, the pestiviruses first attach themselves to cells of the host organism and penetrate the cell envelope. After duplication of the positive-stranded viral RNA strand, budding of the new virus occurs. Viruses of the genus Pestivirus are usually irregularly spherical and about 40 to 60 nm in diameter.
Occurrence, distribution, and characteristics
Viruses of the genus Pestivirus are common in several mammalian species. They are particularly common in pigs and in cattle. Transmission usually occurs through direct contact with diseased animals, which is why pestiviruses may be particularly prevalent in factory farms and large herds. However, infections can also break out on smaller farms, since no symptoms are usually noticeable during the incubation period and there is also a permanent reservoir of the pathogen from some of these viruses in wild forms of today’s farm animals. In addition, pestiviruses can remain infectious for several weeks outside the host body. While the pathogen causing swine fever, which belongs to the pestivirus genus, is particularly common in Europe, viruses that infect cattle are more widespread in other parts of the world. These pathogens are particularly problematic in Australia, where major economic damage is repeatedly caused by a proliferation of pestiviruses. Restricted to Africa is a pathogen of the genus Pestivirus, which preferentially infects giraffes. Animals infected with pestiviruses should not be consumed by humans under any circumstances. Not all animal pathogens can survive in the human organism, but at least some can. If people then eat this meat, they can also fall ill.
Diseases and ailments
The penetration of the viruses of the genus Pestivirus into the cells of the host organism does not necessarily destroy them. Depending on whether this is the case, symptoms vary in type and severity. While infection may pass almost unnoticed in some animals, turning them into permanent excretors, others experience fever, diarrhea, hemorrhage, changes in mucous membranes, and central nervous system disorders. In severe cases, this can take a fatal course. In these cases, death usually occurs due to circulatory failure. Secondary infections can also lead to the death of the animal. Infection with a virus of the genus Pestivirus is particularly problematic if pregnancy is present at the time. In this case, miscarriages or stillbirths may occur. In the case of live births, malformations of the young animals and premature death are possible. In addition, infection with pestiviruses can cause permanent infertility in affected animals. Visible symptoms in this case are only mild symptoms such as low fever and redness of the mucous membranes. The animals appear to recover after a short time, although in reality the disease has become chronic. In addition to the direct damage caused by infertility, these animals also pose a permanent threat to the rest of the herd through continued shedding of the pathogens. In older and robust animals, however, complete recovery may occasionally occur. The viruses of the pestivirus genus include in particular the pathogen causing swine fever and the bovine viral diarrhea virus. Border disease, which can occur in sheep and is named after the English-Scottish border region where it first appeared, is also one of the diseases caused by viruses of the genus Pestivirus. Depending on the species and the virus, different symptoms and consequences come to the fore. While swine fever is usually fatal, cattle and especially sheep mainly experience problems with pregnancy and fertility. Vaccinations are now available for some of these animal diseases.However, these are not approved in all countries because blood tests cannot distinguish between vaccinated and infected animals. As a rule, prophylaxis in livestock is therefore only carried out by strict control of the livestock, separation of new arrivals and segregation of sick animals. In stables, the use of disinfectants can prevent the spread of viruses of the pestivirus genus, as this puts them into an inactive state. In the case of infection with pestiviruses, there is as yet no known treatment for the actual disease; only secondary infections can be treated. In order not to endanger the still healthy animal population, at least all diseased animals are therefore culled, and in the case of swine fever also all healthy animals within a certain radius around the outbreak site. In order to prevent the unhindered spread of diseases caused by viruses of the pestivirus genus and to be able to take successful control measures in good time, an outbreak of one of these diseases is notifiable in many countries. The competent authorities then decide on the necessary measures, organize the culling of the affected herds if necessary, and carry out thorough investigations before animals can be kept again at the respective location. The economic losses are therefore usually very high when infections with pestiviruses occur.
