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A Zika-related virus can overwinter in pigs
The news about the Zika virus, which is blamed for neonatal cranial malformations, is frightening people worldwide. Swiss researchers have now discovered that a virus related to Zika can apparently overwinter in herds of pigs.
Zika-related virus overwinters in pigs
The Zika virus, which has spread for months in Latin America, has been causing great anxiety among the population for months. The pathogen is suspected of causing malformations in the unborn child when pregnant women are infected. In this so-called "microcephaly", the children come with a too small skull on the world. Scientists from Switzerland have now found that a virus related to Zika in the mosquito-free winter time apparently circulating in pig herds and can survive so.
Viruses related to the Zika virus can overwinter in pigs. (Image: Kadmy / fotolia.com) Severe brain inflammation in humans
The Japanese Encephalitis (JE) virus is the leading cause of severe brain inflammation in humans in Asia. Especially in children, infection can lead to severe brain inflammation with lifelong damage or even death. The virus is found in large parts of Southeast Asia and is now common in India. The pathogen circulates between birds and mosquitoes and between pigs and mosquitoes. So far only one infection was known about mosquitoes. Researchers at the University of Bern have now found that it also transmits to direct contact between pigs, which means that it could circulate in swine populations even in mosquito-free winter time.
So far, only transmission path known by mosquitoes
As the University of Bern stated in a press release, the JE virus is closely related to the West Nile, Zika and Dengue viruses. They are all transmitted by mosquitoes and belong to the so-called flaviviruses, which can cause serious illnesses in humans and animals. So far, JE viruses were only known to transmit mosquitoes. The research group headed by Dr. med. Meret Ricklin and Prof. Artur Summerfield, however, found that they can also transmit between pigs. The scientists published their findings in the journal "Nature Communications".
Pathogen can outlast in colder regions
It was previously unknown how the JE virus could overwinter in colder regions such as northern Japan and lead to new outbreaks next year. These outbreaks occurred in part in the same farm as last year, although no infected mosquitoes were found in the environment. The scientists have now found that the animals secrete the pathogen over several days over the saliva and are susceptible to infections of the mouth and nose even at low doses of virus.
Virus multiplies in the brain
As in humans, the virus multiplied in the pigs in the brain and caused inflammation there. However, it increased most in the tonsils of pigs, where it remains detectable for weeks to months. The study authors assume that JE viruses may circulate in the pig and even survive for months. If the animal eliminates the virus again, a new infection cycle could begin. However, further studies are needed to prove these relationships.
Propagation possible in temperate climates
The results showed that direct transmission through contact can not be ruled out even with viruses transmitted by insect bites. "It means that the JE virus could circulate in the pig population even without mosquitoes and thus spread to regions with temperate climates," explained Artur Summerfield. Theoretically, it could also threaten humans more. For humans and animals but there is a vaccine. In Europe, the virus has so far only occurred in Asian returnees, with no further infections. However, in recent years there have been increasing warnings about the spread of the Asian bush mosquito in Europe. This is considered the transmitter of Japanese encephalitis. (Ad)