Rat lungworm
| Rat lungworm | ||||||||||||
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Rat lungworm ( Angiostrongylus cantonensis ) |
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| Angiostrongylus cantonensis | ||||||||||||
| ( Chen , 1935) |
The rat lungworm ( Angiostrongylus cantonensis ) is a parasite whose main host is rats, in whose lungs it lives. Various land snails and crabs serve as intermediate hosts . Marine fish can also be infected experimentally, but it is assumed that the larvae are not very resistant to salt water. Humans can also be infected by the parasite - for example when they eat infected snails that have not been cooked through .
distribution
Original distribution area is the Pacific region and Southeast Asia . However, the worm has since spread to the following areas: Australia, Melanesia, Micronesia and Polynesia, New Caledonia, the Philippines, Rarotonga, Saipan, Sumatra, Taiwan and Tahiti. From the 1960s there were reports from Cambodia, Guam, Hawaii, Java, Thailand, Sarawak, Vietnam and the New Hebrides (Vanuatu). The first description comes from China . The parasite was also introduced into the Caribbean . A few specimens have been found in rats from Cuba , Puerto Rico , the Dominican Republic, and Jamaica . A single case of infection through ingestion of an unknown species of snail was found in Australia. Researchers warned against eating undercooked snail dishes in Mallorca in 2019 ; In 2018, the rat lungworm was found in two hedgehogs on Mallorca.
features
The parasite has the typical nematode shape . The skin is made up of three layers of collagen , which allow the parasite to bypass the host's immune system . The males have a kind of pouch with which the male clings to the female. There is a sexual dimorphism , the females are 25 to 33 mm long, the males, however, only 15 to 19 mm. The body is crossed by an S-shaped black band that represents the intestines and the uterus .
Life cycle
Development begins in the rat in which the adult females live. These are located in the right ventricle and the pulmonary arteries . The eggs are released there. They migrate into the capillaries of the lungs, where the larvae hatch from the eggs, which in the first larval stage break out through the alveoli and are coughed up. Some are swallowed again and are now excreted in the faeces in the second larval stage.
The intermediate host then takes on the larvae through the rat droppings. These develop in it to the 3rd larval stage. A frog or fish serving as a secondary host can subsequently also ingest the larvae by eating the intermediate host. However, there is no more development here.
The main host becomes infected by eating the intermediate host or the secondary host. However, the larva in the snail also actively penetrates the outside, so that infectious larvae are present in the mucus track, which are also ingested by the rat (the main host). There they travel along the nervous system via the bloodstream to the brain. From the brain they spread throughout the body, leave the bloodstream via the capillary and enter the tissue. This is where the 5th larval stage develops. This again visits the brain and then settles mainly in the pulmonary arteries, but other areas such as the eye or the meninges or the central nervous system are also affected. The adult animal develops from the larva in about 6 weeks. After several moults and mating, eggs are released into the blood again.
Human diseases caused by the rat lungworm
Humans can become infected through contaminated food, including intermediate hosts, and the parasite can cause eosinophilic meningoencephalitis (inflammation of the brain and meninges) in those infected . Clinical symptoms of rat lungworm infection are severe headache, meningism and neurological deficits. The disease can progress to coma and death. People with immunodeficiency are particularly at risk (e.g. pregnant women, people infected with HIV, people with congenital immunodeficiencies). The cerebrospinal fluid of those affected typically contains high numbers of eosinophils .
Between 2007 and 2017, 82 people in the US state of Hawaii were infected and several died.
Sources and web links
- Fact sheet of the CDC (Engl.)
- Is rat lungworm heading for Europe? , on: n-tv.de, from October 9, 2019
Individual evidence
- ↑ dpa : Dangerous bet: Eating raw snail , in: Münchner Merkur from May 13, 2010.
- ↑ a b Danger to life: brainworm on the Spanish island of Mallorca - it lurks in the food. In: www.morgenpost.de. September 17, 2019, accessed September 18, 2019 .
- ↑ Meningitis A warning is given against eating snails on Mallorca. In: www.kleinezeitung.at. September 17, 2019, accessed September 18, 2019 .
- ↑ n-tv news: man dies after a snail test of courage . In: n-tv.de . ( n-tv.de [accessed on November 5, 2018]).