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The tsunami of 1964 brought to North America a dangerous mushroom

Full tape of POLIT.RU 04.10.2019 at 09:30

Full tape POLIT.RU

Since 1999, the canadian province of British Columbia and the US States of Washington and Oregon there are cases of infections caused by the fungus Cryptococcus gattii, which were previously found in the tropical areas of South America, Asia, Africa, Australia and New Guinea. According to a new study, the fungus is able to be brought on the Pacific coast of North America to the tsunami caused by the Great Alaskan earthquake of 1964.

the Fungus Cryptococcus gattii belongs to the family kojakovic (Tremellaceae), which received its name from the gelatinous fruit bodies. But this view, like its closest relatives, the fruiting bodies it does not form at all, and reproduces the type of yeast. In nature it occurs in the soil under certain types of trees. Once in the body, human or animal, it causes infectious diseases of the lungs (pulmonary cryptococcosis), shells brain (cryptococcal meningitis) or brain (cerebral cryptococcosis). Disease is enough dangerous, pulmonary cryptococcosis can lead to respiratory failure and death, complications of infection of the nervous system are hydrocephalus, seizures and other neurological symptoms. Over the past twenty years in the United States and Australia identified more than 300 cases of the disease, 27 cases died.

Scientists tried to understand how the fungus, not previously characteristic of this region, got there. According to the proposed hypothesis, the reason for the emergence of Cryptococcus gattii in North America was the earthquake of 27 March 1964, whose epicenter was in the Gulf of Alaska. The earthquake of a magnitude of 8.4 was the strongest in the history of North America. The result of the ensuing tsunami killed 139 people of Alaska.

Genetic analysis showed that the strains of Cryptococcus gattii from the Pacific coast of the USA and Canada are closest to the Brazilian strains. In 2017, a group of researchers suggested that to get into the zone of the Pacific ocean, the fungus could in the ballast water of vessels after 1914 when it opened to traffic through the Panama canal. "Genetic clock" has confirmed this assumption, three Pacific strain was separated from the Brazilian ancestor about a hundred years ago.

But it remained unclear how the ocean spores were in the soil and the trees. Now the researchers suggest that a tsunami of 1964 is a suitable explanation. "It's the only event like no other in recent history, resulted in a strong push ocean water in the coastal forests in the North-West Pacific they write. — This event may have triggered the simultaneous infection with C. gattii forests up and down the coast of the region, including Vancouver island in British Columbia, Washington and Oregon".

To support their hypothesis, the scientists indicate that the fungus is found in forests on the coast and not in the interior of the continent. They even offered an explanation for why the tsunami before the first manifestations of the disease have passed more than thirty years. According to them, when living in seawater Cryptococcus gattii significantly loses its ability to infect humans, and it took time to in the course of evolution in North America, he has again become virulent. Besides, scientists say that the earliest case of strain C. gattii in the Pacific coast happened in Seattle in 1971, long before the outbreak of 1999, which suggests that the fungus was already present in the region.

Scientists believe that other regions affected by recent tsunamis, such as Japan and Indonesia, are also subject to the risk of future outbreaks of infection caused by this fungal species.

the Study is published in the journal mBio.