Ticks in Switzerland transmit more diseases than thought

Ticks can transmit several diseases caused by different pathogens, sometimes simultaneously © Keystone / Gaetan Bally

Ticks in Switzerland do not transmit only borreliosis or encephalitis. They can also cause rickettsial infections and anaplasmosis, according to surprised scientists in Zurich.

These diseases are not investigated during consultations for tick bites, explained Patricia Schlagenhauf, a professor at the Epidemiology, Biostatistics and Prevention InstituteExternal link at the University of Zurich. “They are therefore under-diagnosed and often not treated specifically,” she said on Wednesday.

Schlagenhauf and her team analysed the blood of patients who had contracted borreliosis, or Lyme disease, which along with tick-borne meningoencephalitis is the best-known of the infections transmitted by these mites. They found that 54% of the samples also contained bacteria of the Rickettsia genus and 10% the Anaplasma phagocytophilum bacterium.

Rickettsia bacteria can cause rickettsial infections, with fever and headaches, while Anaplasma can cause human granulocytic anaplasmosis, with flu-like symptoms, fever, headaches, pain and nausea. The risk of death is high in immunocompromised individuals.

“We did not expect results of this magnitude,” Schlagenhauf said. The authors are therefore calling for these diseases to be taken into account in the event of a tick bite. Particular attention should be paid to patients with certain symptoms, such as muscle pain, headaches and persistent fatigue.

Ticks can transmit several diseases caused by different pathogens, sometimes simultaneously. While encephalitis is a viral disease, borreliosis is bacterial, as are rickettsial diseases and anaplasmosis. This work is published in the science journal New Microbes and New Infections.