The city is full of ticks - a new study in Warsaw

Ticks are not just a problem in forests and meadows. As confirmed by a new study by scientists from the University of Warsaw, these parasites are also very common in cities: in parks, botanical gardens, private properties, and even kindergartens. What's more, they are active earlier than is commonly believed.

"The idea to investigate the presence of ticks in Warsaw was born from observations and reports from residents who increasingly reported cases of bites by these animals in urban locations. So we selected several urban and suburban areas, and it turned out that ticks are present in them, and in really large numbers," the lead author of the study, Dagmara Wężyk, a PhD student at the Department of Eco-Epidemiology of Parasitic Diseases, Faculty of Biology, University of Warsaw, told PAP.

For three months—from mid-March to mid-June 2021—she and her colleagues conducted systematic tick collections at 15 different locations. They used a flagging method, which involves dragging a white woolen cloth across the substrate and counting how many arachnids remained.

"Some of the collections surprised us, because for example in the Botanical Garden of the University of Warsaw, at a distance of only 20-30 meters, we collected as many as 30 ticks. We noted equally high numbers in Łazienkowski Park and in the Forest Kindergarten in the Kabacki Forest," explained the author of the publication, which appeared in the magazine "Parasites & Vectors."

Further analysis showed that two species were most common in Warsaw and its surroundings: Ixodes ricinus (the common tick) and Dermacentor reticulatus (the meadow tick). As the biologist explained, each of them carries different threats.

The common tick is responsible for transmitting the Lyme disease spirochete ( Borrelia burgdorferi ) and other dangerous human pathogens, such as tick-borne encephalitis virus or - although sporadically - protozoa of the genus Babesia.

In turn, the meadow tick rarely feeds on humans, but poses a serious threat to dogs because it is the main carrier of the previously mentioned protozoa that cause babesiosis – a potentially fatal disease.

Detailed molecular studies revealed that 14.3% of the Ixodes ricinus ticks tested contained DNA of bacteria from the genus Borrelia , and as many as 64% of Dermacentor reticulatus ticks were carriers of Rickettsia bacteria, which cause diseases with symptoms including fever, headaches and rash, and in some cases serious organ complications.

One of the most important conclusions of the study was the confirmation that the tick season starts earlier than is commonly believed. The meadow tick appears as early as March, just after temperatures exceed zero degrees Celsius, and is also active in winter, especially when it is mild. "That is why we need to take care of protecting our pets against these parasites all year round," noted Dagmara Wężyk.

The common tick, on the other hand, starts attacking a few weeks later, reaching its peak activity in May.

"Many people believe that ticks pose the greatest threat between June and September. Meanwhile, our data shows that we are exposed from March onwards, and mild winters additionally extend this season," the author emphasised.

In her opinion, the collected results clearly show that cities are not much safer in this respect than villages. She recalled that some Warsaw locations actually had a higher density of ticks than suburban areas. The type of habitat is crucial.

"Ticks love lush vegetation, tall grass, bushes and damp places. That is why there will be many more of them in botanical gardens, parks that are not often mowed, allotment gardens and around water reservoirs. In turn, in closely trimmed and very well-kept gardens, pastures, fields or chicken pens, they almost do not appear. Mainly due to the small vegetation cover, the lack of a large number of mammals, which are their main hosts and the presence of hens that can eat them," she added.

Interestingly, the study did not reveal any strong correlations between tick density and temperature or humidity. The impact of these factors turned out to be much smaller than habitat type and season.

The PAP interviewee also stressed that despite the increasing presence of ticks in our environment, one should not panic, but simply be careful. Prevention should be used early enough, and not only in late spring and summer. You can also check your home gardens from time to time - especially if they are overgrown and often watered, by "flagging" them yourself - all you need is a piece of light material and a few minutes of walking on the grass.

However, if a bite does occur, it is crucial to remove the tick quickly. "First of all, remember that it is not true that the moment you bite it, it will immediately transmit dangerous bacteria to you. Only a certain percentage of ticks are carriers of them. In addition, time is important - in the case of Lyme disease spirochetes, the minimum feeding period necessary to infect a human is 24 hours. So if we remove the tick from our body within 24 hours, there is basically no risk of getting sick," said Dagmara Wężyk.

The biologist remains skeptical about the sometimes recommended spraying of properties against ticks. She points out that although they are indeed effective in eliminating these parasites, they also kill other insects and arachnids whose role in the environment cannot be overestimated.

Katarzyna Czechowicz (PAP)

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