Ticks live and thrive in the Alps
There are ticks in them thar hills. It appears that ticks are everywhere, even in the Alps. In the late 1980’s, ticks did not exist or were rare in Italy’s Piedmont region, located at the base of the Alps. But, “In recent years, a marked increase in tick abundance has been observed in several Alpine valleys, together with more frequent reports of Lyme borreliosis,” writes Garcia-Vozmediano and colleagues. 
Over a 4-year period, investigators examined the distribution and prevalence of ticks and their transmitted pathogens, along with the altitudinal limit of Ixodes ricinus ticks (which are similar to Ixodes scapularis ticks in the USA) in the Piedmont region of the Alps.
A total of 6492 I. ricinus ticks were collected from the vegetation. Questing (or feeding) ticks were collected from 373 carcasses of red deer, roe deer, and chamois between 2017 and 2019. (A chamois is a species of goat-antelope.) Many of the ticks on large animals were presumed to have detached during transport since those carcasses were not placed in plastic bags.
The authors report, the number of ticks “was significantly associated with altitude, habitat type, and signs of animal presence, roe deer, in particular.” And although their numbers decreased with the increase in altitude, Ixodes ricinus ticks were still recorded at an altitude of 1884m a.s.l.
Ticks collected included those from all three life stages (larva, nymph, and adult). The Centers for Disease Control and Prevention (CDC) assumes a tick population is established once all three life stages are present.
These findings are remarkable, the authors point out, given that “such altitudes and habitats have been usually considered unsuitable for I. ricinus survival and development, due to extreme temperatures, the low content of secondary vegetation and dry soils.”Ticks present at high altitudes of the Alps and harboring multiple pathogens. Click To Tweet
In utilizing Molecular analyses, investigators were able to identify a broad range of tick-borne pathogens in the ticks including Borrelia burgdorferi sensu lato, Rickettsia Helvetica and Anaplasma phagocytophilum. And although there was a low prevalence, “we detected for the first time Borrelia miyamotoi.”
Global warming, the authors explain, may be contributing to the expansion of ticks to the mountains.
There were fewer ticks in coniferous woods and open areas, the authors write. Yet, public safety is still a concern given that open areas “are more frequented by the public, since they include sites equipped with tables and seats and walking paths, which are often visited by tourists.”
There have been only a few cases of Lyme disease in the Piedmont region. But according to the authors, human cases of Lyme disease are likely underdiagnosed and/or underreported.
- Garcia-Vozmediano A, Krawczyk AI, Sprong H, Rossi L, Ramassa E, Tomassone L. Ticks climb the mountains: Ixodid tick infestation and infection by tick-borne pathogens in the Western Alps. Ticks Tick Borne Dis. 2020;11(5):101489.