“Lumaca killer”, “Dog massacre”, “alarm in Australia” … are terms and phrases with which you have probably come across these days on the web. Let’s clarify: a recent study conducted in Australia from the University of Sydney has highlighted an increase in cases of neural angiostrongilosis in the dog caused not by a snail but by a parasitic worm Originally from Southeast Asia and in but also reported in the United States and Europe, transmitted by snails and other gastroopodes, the nematode Angiostrongylus Cantonensis.
So “Lumaca killer” is only a journalistic term – moreover used only in Italy – which is also misleading: in reality when it comes to “snail killer” (Assassin Snail) means the species Anntome Helena which is carnivorous and feeds on other snails.
A study conducted by Jan Šlapeta And Phoebe Rivory reported 93 cases on dogs from 2020 to 2024 with a peak of 32 cases in 2022, finding a correlation between cases of Canin neurally angiostrongilosis and climatic conditions. The humidity and strong rains favor the proliferation of snails by increasing the risks of contagion.
What is theAngiostrongylus Cantonensis And how to transmit: the contagion cycle
Angiostrongylus Cantonensis or “Pulmonary worm of the rat” It is a nematode (cylindrical worm) parasite that naturally lives at the costs of the rats, with adult specimens that ripen in the lung arteries. It is mainly widespread in Southeast Asia and the Pacific islands but there have also been reports in Africa, and recently, in the southern United States and in Europe.
The life of this worm is a continuous and complex cycle:
- THE’definitive guestis the rat, the only animal in which the parasite can become an adult and reproduce on a lung level.
- The Intermediate guests They are snails, snails and other animals as in which the natural cycle begins when the larvae are expelled with the stool of the rats. The circle closes when another rat, eating a snail, becomes infected in turn, allowing the parasite to complete the development in about six weeks.
- Accidental guests: dogs and human beings become “blind -bottomed” guests if they ingest an infected snail, perhaps hidden in food, or the parasite is found in other transporters such as crabs and raw shrimp or in contaminated waters.
The risks for man and dogs: symptoms and how many human cases are
This parasite causes one zoonosisthat is, a disease transmitted by animals to humans. The larvae of the nematode, expelled with the stools of the rats, in fact pass to snails and filths from which they come to the dogs and, in rare cases, to man. Unlike what happens in the rats, however, once this worm comes into contact with dogs or with the man it reaches the brain and the central nervous system causing the neural angiostrongilosisone meningitis eosinofila Which can bring symptoms such as severe headache, rigid neck, fever and important neurological consequences. Only in rare cases can lead to death. It is essential to underline that the contagion never happens from person to person, but exclusively through the accidental ingestion of larvae present in contaminated foods or water.
In dogs, theCanin neurally angiostrongilosis Instead, it can lead to symptoms such as paralysis of the rear limbs and tail, incontinence and hypertiesia (hypersensitivity to stimuli). According to the study conducted by Rivory, the mortality for dogs varies from 14% to 58%.
In Australia, where neural Angiostrongilosis has been identified for the first time over 50 years ago, dogs are considered important “Sentinel animals“, Since their cases can anticipate an increase in risk for the human population. Despite the presence of the parasite, human cases in the country remain rare: since 1971 they have been documented about it 34with at least 2 mortal outcomes. One of the best known is that of Sam Ballarddeceased 8 years ago after contracting the infection for ingesting a contaminated snail.
The spread of the parasite seems not to limit itself to Australia. An article from 2023 has documented an infection in Valencia, Spain, while in Italy, at the moment, only sporadic cases have been reported in people returning from travel to endemic areas of Asia.
The study on the increase in cases in dogs in Australia and climate change
The study conducted by Rivory highlighted an increase in cases of Angiostrongilosis on the eastern coast of Australia, with a clear connection to climatic factors. Specifically, 93 cases have been identified (on 180 suspicious cases studied) of dogs that contracted this disease caused by the nematode Angiostrongylus Cantonensis In a period of 5 years from 2020 to 2024. The peak was recorded in 2022, with 32 cases, and the areas with the greatest number of confirmed cases are mainly around Sydney and Brisbane.
For the authors of the study there is one correlation between the diffusion of the disease and climate changein fact, meteorological events intended with strong and prolonged rains create the ideal environment for the proliferation of snails and locks, the intermediate guests of the parasite. In addition, global warming brings rats, snails and the parasite itself to adapt and survive even in previously “uninhabitable” areas. The peak of 2022 was precisely in conjunction with substantial climate events and the research defined the period of time between 2 and 10 months after an event of strong rains where the risk for the transmission of the disease increases.
