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Hepatitis A viruses found in seals
Hepatitis A is a highly contagious infectious disease that causes acute liver inflammation. So far it has been assumed that in addition to humans only primates are susceptible to the hepatitis A virus. But US scientists made now an interesting discovery: they discovered by chance a precursor of the pathogen also in seals. This indicates that the virus has jumped from the animal to humans at some point, the report in the journal "mBio".
Every year about 1.4 million infections
Hepatitis A is an inflammation of the liver tissue caused by the hepatitis A virus. It is primarily transmitted through contaminated food (such as mussels), contaminated drinking water or direct contact with an infected person ("contact infection"). Worldwide, about 1.4 million people are infected with the virus every year, with the disease occurring particularly frequently in warm, tropical regions as well as in countries with a low standard of hygiene
Researchers have detected hepatitis A viruses in seals. (Image: Christian Colista / fotolia.com) Hepatitis first manifests itself by nonspecific symptoms
Hepatitis A never progresses chronically and usually heals spontaneously without serious complications; in childhood it often even goes unnoticed. In adults, about two to seven weeks after infection, nonspecific symptoms such as diarrhea, fatigue, headache, nausea, and vomiting usually occur. In addition, in some cases, there are typical signs of jaundice such as yellow eyes and skin, light bowel movements, and dark urine.
So far, experts have assumed that in addition to humans only marmosets, chimpanzees and other primates could be attacked by the pathogen. But now researchers at the Mailman School of Public Health at Columbia University in New York have been able to prove the virus in seals. As the scientists around Simon Anthony report in the journal "mBio", this is actually the next related pathogen of human hepatitis A virus (HAV).
Researchers find hepatoviruses by accident while studying an avian influenza strain
"So far, we did not know that hepatitis A has close relatives, and we thought that only humans and other primates could become infected with hepatovirus," Anthony said, according to a Columbia University press release. "Our results show that hepatoviruses are not restricted to primates and suggest that many more can occur in other wildlife species."
According to the find, it points out that a predecessor of HAV comes from the animal kingdom: "At some point in the past, it must have jumped over. This raises the question of whether hepatitis A originated in animals, like many other viruses that have since adapted to humans. "As the scientists report, they had accidentally become aware of the pathogen when they examined a bird flu strain , which caused the death of 150 seals in New England in 2011 (Phoca vitulina vitulina).
Pathogens detected in several seal species
The researchers gave their find the name "Phopivirus", as they first found it in dead animals of the family of dog seals (Phocidae). But in further investigations, they discovered the pathogen in eleven seals and a harp seal, the report continues. That occurrence in different species show that it has apparently been circulating among aquatic predators for some time: "Our data suggest that hepatitis A and the new virus share a common ancestor," says Anthony.
The next step will be to investigate in which other species of the Phopivirus still occur, write the scientists. For example, coyotes may be an option, as they "regularly devour dead seals along the coast," says co-author Katie Pugliares of the New England Aquarium in Boston. "Therefore, it would be interesting to investigate if they carry similar viruses." (No)