Is it true that there were significantly fewer ticks in the USSR than in modern Russia?

It is widely believed that during the Soviet era there were much fewer ticks and they bit people less often. We decided to check whether this is supported by statistical data.

The almost complete absence of ticks in the Soviet Union is often written in the media: “Russian seven", "Moskovsky Komsomolets", "Arguments and facts" This topic is also popular in blogs such as posts is on "Zene" And "Peekaboo", in "VKontakte", V "Pulse Mail.ru", on YouTube and in LiveJournal.

Ticks are representatives of a subclass of arthropods from the class of arachnids. They make up the most numerous group in the class - more than 54,000 species have been described, including 144 fossils. Interestingly, ticks hardly evolved - 242 million years ago, these animals were minimally were different from his contemporaries. Some scientists even suggestthat ticks, which carried various deadly diseases, together with malarial mosquitoes, became one of the reasons for the extinction of dinosaurs.

Today, the most dangerous family of ticks for humans and animals is the Ixodidae. These arthropods are distributed throughout the entire planet, including the Arctic and Antarctica (for example, described species that parasitize penguins). Scientifically, the type of feeding of ticks is called obligate hematophagy, that is, for further development the animal every phase of its life (larva, nymph of the first stage and sometimes the second, and then the imago, that is, an adult) should feed on the blood of another creature. Larvae eat with the blood of small rodents and birds, nymphs that have molted over the winter hunt larger animals - hares, hedgehogs, chipmunks. And only after turning into an imago, the tick shows interest in human blood. The life cycle of a tick, depending on the species, ranges from several days to ten years. If external conditions are unfavorable, ticks may leave in diapause - an analogue of hibernation, during which they become almost immune to any toxic substances.

Ticks can carry a variety of pathogens. The first group are viruses, for example Flavivirus, which causes tick-borne encephalitis, a serious disease characterized by fever, intoxication and damage to the gray matter of the brain and the membranes of the brain and spinal cord (meningitis, meningoencephalitis, encephalomyelitis). This disease can lead to severe neurological and psychiatric complications, as well as death of the patient. Fatal outcome comes in 1–3% of cases when infected with the European subtype and reaches 40% with the Far Eastern subtype. At the same time, from tick-borne encephalitis exists effective vaccine. 

Also, when bitten, a tick can infect a person with protozoa, such as trypanosomes, which cause Chagas disease, which can lead to irreversible damage to internal organs, primarily the heart. Its lethality reaches up to 10%, there is no vaccine. Also, a dog can become infected with dangerous protozoa when bitten by a tick - in particular, piroplasmids cause serious blood diseases: babesiosis, theileriosis and nuttalliosis. Babesiosis (pyroplasmosis) is especially dangerous for small, elderly or weakened animals, they are usually can't cope with the disease and die from the destruction of red blood cells. There is also no vaccine, but antiparasitic drugs have some effectiveness. 

The next group of dangerous pathogens are the parasitic roundworms filaria, which amaze different organ systems: lymphatic, causing elephantiasis - pathological growth of the skin and subcutaneous tissue, gastrointestinal and cardiac. The parasite can also live under the skin, in the brain, in the testicles or inside the eyeball, causing blindness. 

Ticks also carry dangerous bacteria - spirochetes and rickettsia. The former cause Lyme disease, another name is tick-borne borreliosis, which is manifested by headache, nausea, migrating pain in bones and muscles, general weakness, fatigue and fever with a temperature rising to 40 ° C. This disease responds well to antibiotic therapy, also in 1995 appeared a vaccine against it, but in the wake of the anti-vaccination movement it turned out to be unclaimed and was discontinued. Now are underway developing a vaccine based on mRNA technology. In turn, rickettsia causes tick-borne typhus, which accompanied by fever, headache, muscle pain and characteristic rashes, the prognosis with proper treatment is usually favorable.

Considering the number of diseases carried by ticks, measures to reduce the population of these arthropods are very justified. In recent years, the incidence of tick-borne encephalitis and borreliosis has been particularly increasing in Russia, which is regularly reported by Rospotrebnadzor, without publicly publishing generalized statistics on tick bites for different years. For example, in 2015 the department indicatedthat the situation in May is “approximately at the level of the same period last year” (129,422 victims), in June — “the number of victims of tick bites increased by 15%” (235,281), in July — “the number of victims of tick bites increased by 21%” (361,559), in August — “the number of victims of tick bites increased by 19%” (478,291 since the beginning of the year). There are no final data and in the media. In the opening tick season press release dated April 1, 2016, it is said that “in the epidemic season of 2015 (from April 1 to October 1), more than 500,000 cases of people contacting medical organizations about tick bites were registered in the country, which is 22% more than in 2014.” Moreover, in 2016 changed and the calculation method: if in 2015 the department indicated the number of citizens who applied to medical institutions for bites, then in the 2016 reports this parameter was changed - there are figures only for the ticks examined. That is, if in 2015 a person was bitten by a tick, he got rid of it on his own, and came to the hospital to consult a doctor, then he was included in the statistics, but in 2016, without a tick on him, he was not taken into account in the statistics. The results of the season have not been summed up in principle - the latest bulletin records the situation as of August 12. By that time, there was already a number of visits to the hospital - 419,000 (an increase of 12% compared to the same period last year). This somewhat contradicts the department’s earlier comments in the media: for example, in May 2016, Rospotrebnadzor told Kommersant reported: “The number of people complaining about tick bites has quadrupled compared to the same period last year” (publication dated May 5, 2016). 

Thus, it is impossible to collect methodologically clear statistics on tick bites even over the last 10 years, let alone trace the dynamics since the times of the USSR.

However, there are several factors that could actually lead to more ticks. The first thing to note is global warming. And although ticks can live even in the harsh conditions of high latitudes, those species that live in the forests of Russia are most comfortable feel at an average daily temperature above +15 °C. For example, 2020 was the warmest on record - the average annual temperature was 3.22 °C above normal. The rate of temperature rise in Russia much higher than the global average – “from 1976 to 2019 [the increase] averaged 0.47°C per decade.” That is, the duration of the tick season itself has increased: arthropods wake up earlier, fall asleep later, and they have more time to potentially bite people.

The second important factor is the level of awareness about the dangers of tick bites. From April 1, 2023, search for “tick bite” on Google issued about 250 publications. Now the patient is more likely to go to a medical facility and be included in the statistics, rather than staying at home and unscrewing the tick himself. If the tick was uninfected, no adverse health consequences will occur and the fact of the bite will not be reflected anywhere.

Finally, the third and perhaps most important factor is what can roughly be called forest management. Firstly, to transition from stage to stage, a tick requires a special environment - a moist and warm bedding of grass, fallen leaves and dead wood. During the Soviet era, agricultural spring fires the grasses simply left the ticks significantly fewer secluded places to molt. About the importance of such prevention, for example, written in the article “Ixodid ticks” in the third edition (1974–1989) of the “Big Medical Encyclopedia”: “The fight against ticks includes forestry and agricultural activities (clearing forests of dead wood, burning herbaceous vegetation before the beginning of the growing season, improving the health of pastures and haylands, their correct replacement, etc.).” The same article also talks about the use of special acaricidal (that is, “killing ticks”) drugs: “According to epidemiological indications, focal areas are treated with acaricides (DDT preparations, hexachlorane and organophosphorus compounds). In steppe and desert areas, burrows are treated with combined aerosols to combat ticks and their hosts. Acaricidal aerosols are used to treat premises where livestock are kept. Livestock is treated with organophosphorus compounds.” 

DDT, known to chemists as dichlorodiphenyltrichloromethylmethane (C₁₄H₉Cl₅), is a strong acaricide and insecticide. In 1939, Swiss chemist Paul Müller, studying DDT, already known to scientists, discovered that it was extremely effective in killing various crop pests. In 1948, Müller was awarded the Nobel Prize in Medicine and Physiology with the wording “for the discovery of the high effectiveness of DDT as a contact poison.”

At the same time, the substance saved not only the crop - in 1944, DDT was able to prevent typhus epidemic in Naples. The main carrier of typhus is the body louse. In order to rid people of these insects, 1.3 million people were sprayed with a 5% solution of DDT; there were no serious side effects other than isolated skin reactions, and the epidemic was defeated at the very beginning. According to the American National Academy of Sciences, the use of DDT also saved 500 million people from malaria by killing its carriers - mosquitoes.

However, in 1962, the American writer Rachel Carson’s book “Silent Spring” was published, in which the author argued that DDT impairs the reproductive function of birds. Many environmental activists sided with Carson. By the end of the 1970s, most countries had phased out the use of DDT. USSR formally entered such a ban in 1969, but in practice in some regions the insecticide was used until the early 1990s. Also indicative experience South Africa: After the country banned the use of DDT in 1996, the incidence of malaria increased sixfold, leaving authorities with no choice but to allow its use again. All these years, WHO, one might say, remained neutral - it did not ban DDT, but also did not finance its purchases by developing countries, as is the case with other drugs.

At the same time, scientists have a lot of questions. Firstly, it often relies only on anecdotal evidence like “there used to be a lot of birds in our village, but now there are few.” Secondly, her data contradicts the observations of ornithologists - the number of birds in these years in the United States, on the contrary, increased. Third, she cites the work of James DeWitt, who mixed high doses of DDT into bird feed and then concluded that only 80% of the eggs in the group that regularly received the supplement hatched. This indeed sounds alarming, if you do not take into account the fact that in the control group this figure was not much higher - only 83.9%. In 2012, on the 50th anniversary of Silent Spring, in the journal Nature published a critical letter from a group of scientists stating that the abandonment of DDT was unfounded. The letter's authors argued that "unfounded fears based on poorly understood observations have resulted in between 60 and 80 million premature and unnecessary deaths, mostly among children." Popularizer of scientific thinking and factuality Hans Rosling believes public wariness towards DDT is one of the most important causes of chemophobia - fear of chemicals. Chemophobes try to avoid “chemistry” wherever possible - in cosmetics, in everyday life and in products, not realizing that the whole world consists of chemical elements and it is simply impossible to eat “non-chemical” foods.

Returning to ticks, we can assume that DDT, which was regularly sprayed over large areas, played a key role in reducing their population during Soviet times. Firstly, this insecticide was relatively cheap to produce, secondly, treatment could be carried out even from airplanes, which made it possible to influence large areas, thirdly, the drug acted for a long time - treatment in early spring was enough for the whole season. On the importance of DDT processing in a commentary to Kommersant spoke out Leading researcher at the Laboratory of Natural Focal Infections of the Central Research Institute of Rospotrebnadzor Lyudmila Karan: “In the 1970s, for example, in the Kemerovo region, where there was a very high number of cases of encephalitis, an experiment was carried out on the total treatment of all territories with DDT. Due to its long action, all three generations of ticks of the three-year development cycle were destroyed.” 

Unfortunately, humanity does not yet have a full-fledged and safer analogue of DDT, and in list it is not included in the list of approved pesticides and agrochemicals. Modern drugs against ticks, firstly, have short period of action, and treatment must be carried out several times per season. Secondly, the state no longer organizes mass cultivation of all forest zones. Instead, the current SanPin assumes, that legal entities and individual entrepreneurs must ensure acaricidal treatment of “territories of parks, squares, cemeteries, health centers and organizations, places of mass recreation and stay of the population, as well as adjacent territories at a distance of at least 50 m.” This selective treatment also promotes the further spread of these arthropods.

Thus, there is a possibility that there were indeed significantly fewer ticks in the USSR. Global warming has extended the season when the average annual air temperature has become more favorable for their appearance, and the abandonment of such an effective insecticide as DDT has led to an increase in the number of all kinds of insects and arachnids, including ticks. The systematic cultivation of large territories, which is now absent, and the peculiarities of farming also played a role. However, accurate measurements of the number of these arachnids were not carried out either then or now. Moreover, only those who sought help after being bitten are included in the statistics. Therefore, it is also impossible to obtain exact figures about those bitten.

Cover image: Serebryany Bor (Khoroshevsky forest park), a forest area in the west of Moscow. Photobank Moscow-Live

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