Raccoons may look cute and harmless with their “robber mask” and fluffy fur, but they harbor all sorts of dangers. Researchers have discovered that five parasites that are dangerous to humans circulate in raccoon populations in Germany, including the raccoon roundworm. Raccoons can also transmit dangerous viruses, but they are apparently not yet circulating in these animals in this country.
The raccoon originally comes from North America, but is now also widespread in Germany. The feed of the invasive omnivores consists of around 40 percent plants and around 60 percent animal components such as meat and eggs. The raccoons find all of these in abundance in the vicinity of humans. In urban areas, for example, garbage cans, compost heaps and gardens are a rich source of food. But the increasing proximity to humans is dangerous for us, because raccoons are known to be potential vectors of viruses and parasites.
Virus check on over 200 raccoons
In order to find out which pathogens and parasites that are dangerous to humans are actually circulating in the German raccoon population, researchers have carried out two extensive studies. In the first study, a team led by Norbert Peter from the Goethe University in Frankfurt am Main examined a total of 234 wild raccoons for the various parasites they carry in and on themselves. The second study looked at whether viruses dangerous to humans are circulating in populations. The focus of Markus Keller from the Friedrich Loeffler Institute and his colleagues was primarily on the corona virus SARS-CoV-2, the West Nile virus and the Usutu virus. They examined 229 raccoons to see whether they could become infected with the various viruses and whether they had ever come into contact with them.
As far as the viruses are concerned, the researchers can at least give the all-clear for the time being. All examined blood and tissue samples were molecular-biologically negative. So there is currently no concrete evidence that the various viruses are or were in circulation in German raccoon populations. The evaluation of the blood tests also showed that raccoons apparently cannot become infected with SARS-CoV-2. “However, the serological findings show that raccoons can be infected with both the West Nile virus and the Usutu virus,” explains Sven Klimpel from Goethe University, who was involved in both studies. He recommends continuing to monitor populations in the future.
Raccoon roundworm on the rise
However, the results of the parasite study are less “rosy”. The researchers were able to identify a total of 23 different types of parasites in the raccoons they examined. A large proportion of these were not previously known to occur at all in European raccoons. The scientists’ findings mean bad news for us humans, because five of the 23 discovered parasite species can also infect us. An example of this is the raccoon roundworm Baylisascaris procyonis, which was found in 95 percent of the animals examined. In raccoons, the worms live in the small intestine and usually do not cause any significant symptoms, but in humans, in the worst case, a worm infestation can lead to organ damage, blindness and even death.
As more and more raccoons live near humans, the probability of transmission will increase in the future, the scientists suspect. “The ongoing spread of raccoons and the associated spread and transmission of their parasites increases the potential health risk for wildlife and livestock, as well as for us humans. An increase in parasitic diseases in humans, such as those caused by raccoon roundworms, is to be expected, particularly in urban areas,” says Klimpel.
Source: Senckenberg Research Institute and Natural History Museums; Specialist article: Viruses, doi: 10.3390/v14112559; International Journal for Parasitology: Parasites and Wildlife, doi: 10.1016/j.ijppaw.2023.01.003