Swiss ticks carry multiple pathogens

Viruses or bacteria were found in almost every tick.

Scientists at the University of Zurich examined Swiss ticks for a study: “Almost every tick can potentially make you ill,” said virologist Cornel Fraefel from the University of Zurich (UZH), who was involved in the study. “In many ticks we found several pathogens simultaneously.”

The researchers found the novel Alongshan virus almost twice as frequently as ticks carrying TBE pathogens.

The Alongshan virus (ALSV) was detected in almost twice as many ticks (7.6 percent) as the well-known tick-borne encephalitis virus (TBE virus) (4.2 percent). However, how dangerous ALSV is remains unclear. “The discovery of ALSV is so new that it is not yet possible to say whether it is relevant to public health in Switzerland,” Fraefel emphasized. According to a study from China, the symptoms resemble those of TBE.

Together with colleagues, the virologist extracted the RNA and DNA from over 10’000 ticks from rural and urban areas in ten cantons and searched them for viruses. In addition, the ticks were tested for various bacteria using PCR tests. The results were published on Monday in the journal «Plos One».

A study suggests that the extinction of mouse-hunting predators, particularly the fox, is the cause of the rising number of tick-borne diseases.

Surprisingly large numbers of bacteria found in ticks

«We were surprised by how many ticks we found bacteria in», said Fraefel. Thus, 77.2 percent of the ticks examined tested positive for at least one non-viral pathogen. Among ticks collected in urban areas, as many as 83.9 percent contained at least one non-viral pathogen.

The most commonly found were bacteria of the Rickettsia group, which can trigger a whole range of diseases known as rickettsioses. These include anaplasmosis, which can cause fever, chills and headaches.

But Borrelia, responsible for Lyme disease, were also detected in many ticks. In urban areas in 8.2 percent of ticks, in rural areas in 1.9 percent.