Rate of treatment demand of Omsk region population due to injuries caused by animals: dynamics and structure

Introduction

According to the World Health Organization, animal bites are a significant public health problem and contribute to morbidity and mortality worldwide. Each year, contact with animals results in tens of millions of injuries, with children being most at risk¹ [1].

Almost all animals can potentially injure humans, but the probability of this event and its consequences vary between species. This makes the analysis of the population’s demand for medical care after contact with animals an acute issue.

The obtained results are applied in the individual practice of medical specialists and public health management. They are the basis for measures aimed at improving the health awareness of the population, which is necessary to prevent dangerous contacts with animals, as well as related cases of disease and death [2].

The aim of the study was to analyze the population’s demand for medical care after contact with animals in the Omsk Region.

Materials and Methods

In this paper, the authors studied the data of applications in the Omsk Region for medical care because of injuries caused by animals in 2009–2022, including detailed data on the type of the traumatizing animal in 2009–2015, wild animals – in 2009–2012. Statistical materials were obtained from the Federal Service of Rospotrebnadzor, the Department of Rospotrebnadzor in the Omsk Region, and FBUZ “Center of Hygiene and Epidemiology in the Omsk Region”. Indicators of official demographic statistics are given according to Omskstat data². To characterize the level, structure, and dynamics of people seeking medical care, a descriptive-evaluative epidemiological method of research was used. Intensive indicators were calculated per 100 thousand population.

The peculiarities of injuries caused by domestic owned (dogs and cats with an owner), domestic neglected (stray dogs and cats), and wild (including synanthropic rodents) animals were analyzed. Injuries caused by farm animals and hand-raised rodents were included in the group of injuries from domestic owned animals due to their insignificance. Injuries from epidemically significant wild predators: foxes, raccoon dogs, representatives of the marten family, squirrels, and other wild and synanthropic rodents were analyzed separately.

The multiyear dynamics of application for medical care and age peculiarities of traumatized people are characterized in comparison with the indicators established for the Russian Federation and the Siberian Federal District (SFD).

Statistical processing and design of materials was performed using Microsoft Office 2010 software (Word, Excel).

Results

In 2009–2022, a total of 65,142 people who suffered from bites, scratches, and saliva contact by animals applied to traumatological centers of the Omsk Region, which averaged 4,653 applications per year (239.3 cases per 100 thousand population). In other regions of the SFD, the similar indicator was 210.0–412.0 per 100 thousand population [3]. In the specified period, the rate of the population’s applications for medical care for injuries from animals in the Omsk Region did not statistically differ from the indicators established for the SFD (239.0) and overall Russia (279.1) (p < 0.05). During this period, in the region, there was a moderate trend of a decrease in injuries caused to people by animals (T_cn= -1.16%) from 270.0 cases per 10 thousand population in 2009 to 219.5 – in 2022.

The Omsk Region belongs to the regions with a high (351–550 cases per 100,000 children) rate of traumatization of children aged 0–17 years old by animals [4]. In 2009–2022, this indicator was 400.6 per 100 thousand children. For the SFD and the overall territory of Russia, the similar indicators were 411.0 and 404.4, respectively. The number of applications from children under 14 years old for the Omsk Region was also high and amounted to 464.5 per 100 thousand children (20,323 people). This is higher than in the SFD (425.9) and overall in Russia (416.6). The analysis of applications revealed the absence of a downward trend in injuries inflicted on children aged 0–14 years old (T_cn= -0.5%) in contrast to the general statistical indicator for the Omsk Region.

In 2009–2022, 30.2% of children aged 0–17 years old applied for medical care for injuries caused by animals in Russia. The rate of children under 14 years of age was 26.6% of the injured. In the SFD, the figures corresponded to 34.3% and 30.6%, respectively. In the Omsk Region, 36.5% of children aged 0–17 years old applied for medical care for injuries caused by animals, and 30.2% of children aged 0–14 years old. Of the latter, children under 1 year of age accounted for 1.1%, 1–2 years – 11.8%, and 3–6 years – 32.5%. Children over 7 years of age accounted for 54.6% of all injured children. Thus, about one-third of all people traumatized by animals are children overall in Russia and in the SFD and in the Omsk Region, in particular.

The explanation for such high registration of children’s injuries is their greater (in contrast to adults) propensity to contact with animals and the increased vigilance of adults regarding children’s health. These reasons explain the high rates of adults reporting their children’s injuries to medical institutions. The greater share of injured children 7 years and older is explained by the social activity of this children’s contingent and the simultaneous decrease in control over growing children by adults.

According to the WHO data, dogs cause the maximum number of injuries to people worldwide among all categories of animals. In the Omsk Region, the leading role in the structure of requests for medical care after contact with animals belonged to injuries caused by domestic owned animals – 67.1% (170.0 cases per 100 thousand population), and of these, in 75.4% of cases – by dogs (130.0 cases per 100 thousand population) [5]. Domestic owned cats injured people in 23.0% of cases (40.0 cases per 100,000 population), and in 1.6% of cases, the species was not specified. In the period of 2009–2015, a decreasing trend of attacks by domestic dogs (T_cn= -5.2%) and cats (T_cn= -2.6%) on people was revealed in the region.

The second place by the number of inflicted injuries belonged to stray animals – 30.3% (80 per 100 thousand population). In contrast to bites of people by domestic dogs, a moderate increase in this indicator was noted (T_pr=2.0%). Among all the victims of stray animals, 79.6% were traumatized by dogs (60.3 per 100 thousand population) and 15.4% – by cats (10.2 per 100 thousand population). There was an increase in the incidence of stray dog attacks (T_pr=2.1%) and an extremely pronounced increase in stray cat attacks (T_pr=20.7%).

It is known that along with dogs, cats have epidemiologic importance as a source of rabies infection. Before World War II, the specific weight of cats in human rabies infection on the territory of Russia was 2.0%. At the beginning of the 21st century (2000–2017), this indicator increased by 9 times, rising to 18.4% [6]. When people had contact with cats, in 28% of cases, they forgot that they had been bitten by these animals [7]. Consequently, health education and preventive measures regarding human contact with cats require special attention [8].

The smallest share of applications was for cases of human contact with wild animals and synanthropic rodents (2.7% – 6.7 cases per 100,000 population), which corresponded to the all-Russian indicator (2.5% – 6.5 persons per 100,000 population) and the indicator for the SFD (2.2% – 5.5 persons per 100,000 population). However, despite the insignificant specific weight of these indicators, the rate of citizens’ applications for medical care for such injuries in 2009–2015 was growing (T_pr=13.4%) and increased from 1.9% in 2009 to 5.2% in 2015.

In 2009–2012, wild and synanthropic animals attacked 434 people in the Omsk Region. In 33.6% of cases, people were bitten by squirrels, in 34.6% of cases – by other rodents (rats, house mice, muskrats, and others), and in 17.1% of cases – by foxes. Raccoon dogs (1.4%) and predators of the marten family (1.8%) caused the least number of injuries. In 2.8% of cases, residents of the region were injured by monkeys, lynxes, hedgehogs, and other animals, including unidentified animals. The long-term average injury rate per 100,000 population was 2.0 each for squirrels and other rodents, 1.3 for foxes, 0.1 each for marten and raccoon dogs, and 0.2 for other wild animals. During the study period, the number of attacks by squirrels (T_pr= 17.0%) and wild and synanthropic rodents (T_pr= 16.5%) increased significantly, while the number of attacks by foxes, raccoon dogs, and martens decreased (T_cn=-11.4%, T_cn=-33.3%, T_cn=-30.0%).

The increase in the number of Omsk residents seeking medical assistance after bites and scratches inflicted by squirrels is noteworthy. In the period from 2009 to 2015, the number of these animals fluctuated in the Omsk Region from 12.3 to 32.2 thousand individuals. They were and are often found nowadays in parks and squares of Omsk and the Krasnoyarsk-Chernoluchensk recreation area. The degree of synanthropization of these rodents is increasing, the animals are constantly fed and are not afraid of people. They are ready not only to take food from hands, but also to attack passers-by, demanding treats (they jump on their legs, try to reach hands, bags, and pockets through clothes). Such animal behavior is often accompanied by bites and scratches to both adults and children. Residents of other regions, such as the Krasnoyarsk Territory, face similar problems³.

Squirrels, like any mammals, are susceptible to rabies infection. In the entire history of monitoring for this infection on the territory of both historical and modern Russia (1534–2022), only one case of human infection with hydrophobia from a squirrel, described by N.N. Marie in 1909, was recorded [9][10][11].

Testing of tens of thousands of wild and synanthropic rodents in rabies-endemic areas of Russia and around the world revealed only exceptional cases of infection in these animals⁴ [1][12]. This feature has been known to epidemiologists since the first half of the twentieth century [13]. In 1939, Pikul described the detection of Babesh-Negri bodies in two rats that had bitten people, but the people did not fall ill [14]. Rats have never been a source of human infection in the entire foreseeable history of human hydrophobia in Russia, although they regularly interact with major lyssavirus hosts, such as stray dogs [15]. Also, Selimov [14][16] described two casuistically rare cases of human deaths from rabies after gopher bites on the territory of the USSR in the period from 1941 to 1974.

These facts indicate that squirrels, as well as other rodents, are practically not epidemically significant sources of rabies, so the need for post-exposure antirabies prophylaxis should be considered on a case-by-case basis.

In the territory of Russia, publications describing cases of detection of rabies-infected squirrels, rats, and hedgehogs periodically appeared in the mass media. The authors of the article regard them as overdiagnosis [6]. Such reports may contribute to an increase in the number of people seeking antirabies treatment after contact with these rodents. In order to reduce the rate of dangerous contacts with squirrels, it is necessary to raise the population’s awareness. It is necessary to explain that in parks, squares, and recreation areas, animals should be fed only in specially designated places, placing food in special feeders, on feeding tables. One should know, especially children, that it is unacceptable to feed squirrels from hands, try to play with them, or take pictures. It is imprudent to consider these animals, which are part of the wildlife, as harmless. Squirrels can cause serious injuries to humans and become a source of infectious diseases other than rabies, such as tularemia and leptospirosis [17–20].

Conclusions

In 2009–2022, the rate of application for medical help for animal injuries in the Omsk Region (239.3 cases per 100,000 population) corresponded to the indicators established for the SFD (239.0) and the overall territory of Russia (279.1) (p < 0.05). During this period, in the region, there was a moderate tendency of a decrease in injuries inflicted to people by animals (T_cn= -1.16%).

The Omsk Region is one of the regions with a high (351–550 cases per 100,000 children) rate of traumatization of children aged 0–17 years old by animals. In 2009–2022, 36.5% of children aged 0–17 years old were traumatized by animals. Children under 14 years of age accounted for 30.2% of the injured. This peculiarity is typical for the whole territory of Russia and for the SFD.

The leading role in the structure of requests for medical care after contact with animals belonged to injuries caused by domestic owned animals (67.1%). The second place was occupied by unauthorized dogs and cats (30.3%), and the third place – by wild animals and synanthropic rodents (2.7%).

Among the owned and stray animals, dogs caused more than 70% of injuries. There was a dangerous increase in the number of attacks by stray dogs (T_pr=2.1%) and an extremely pronounced and very dangerous increase in attacks by stray cats (T_pr=20.7%).

From the population of wild animals, squirrels (33.6%) and other rodents (34.6%) most often traumatized the residents of the Omsk Region. Injury of people by other wild animals is registered episodically and is subject to monitoring and prompt epidemiological analysis.

In order to reduce the rate of dangerous contacts with wild animals, in particular, with squirrels, as well as with domestic pets, it is necessary to raise the population’s awareness of the issue. It is necessary to conduct hygienic education and training of the population, including children, on safe and responsible handling of animals and the need for 100% vaccination of domestic predators (dogs, cats, martens, etc.) against rabies.

It is necessary to consider installing warning signs in parks and recreation areas with a ban on feeding squirrels from hands and install feeding tables and feeders.