It's time for natural focal diseases

The main characteristic of natural focal diseases is that their pathogens are transmitted to humans from birds or animals. As a rule, this happens through the bites of blood-sucking insects, such as mosquitoes, ticks. In one natural focus, several pathogens can coexist - bacteria, viruses, helminths, protozoa, etc.

In order to protect yourself from natural focal diseases, many of which pose a serious threat to people's lives, it is important to have information about the ways of transmission of infection and ways to prevent diseases. What is a "natural hearth"? The phrase "natural focus" directly indicates that the source of infection exists in nature. Pathogens of natural focal diseases tend to be transmitted from people to animals, which means that a person who finds himself in such a biogeocenosis can be infected. In this case, pathogens are transmitted in various ways: through insect bites, by inhaling dried excrement of infected animals, etc.

Infection with natural focal diseases can occur in various ways: industrial infection is associated with work carried out on the territory of forests or near them, infection can occur during construction or logging operations, during the harvesting of flax, vegetables, etc.  Often, infection occurs when working in a dacha: often rodents that are carriers of infections live in dacha houses or sheds, then infection can occur when inhaling dried excrement of mice and rats. There is a domestic infection that often occurs in houses located near forests, due to the fact that rodents enter sheds, cellars or living quarters; infection during a short stay in the forest, for example, on a walk or on a hiking trip.

Currently, a large number of natural focal diseases are known. In the Lipetsk region, the most common are: hemorrhagic fever with renal syndrome or the so-called "mouse fever", leptospirosis, pseudotuberculosis, tularemia, rabies, tick-borne borreliosis.

Hemorrhagic fever with renal syndrome (HFRS) is an acute viral natural focal infectious disease characterized by damage to the vascular system (hemorrhagic syndrome) and the development of acute renal failure, which can lead to death.

Pathogen: the virus enters the human body through the respiratory tract, gastrointestinal tract and damaged skin.

Sources: mouse-like rodents (red vole) that secrete the virus in the urine and feces, which can infect the environment, food and household items.

Transmission routes: aerogenic (air-dust), inhalation of dust infected with rodent secretions, and alimentary (infected food). (The virus enters the human body through the respiratory tract, gastrointestinal tract, and damaged skin).
Infection, as a rule, occurs when traveling to suburban areas, when visiting forests, eating unboiled well or spring water, and contact with environmental objects contaminated with rodent secretions.

Leptospirosis is an acute infectious natural-anthropurgical bacterial disease, the main clinical manifestations of which are symptoms of damage to the vascular system, liver and kidneys, with the development of acute liver or kidney failure.

Pathogens: bacteria of various types that are inherent in individual animal species - pigs, dogs, rats, etc. Leptospira enter the human body through damaged skin, intact mucous membranes and the gastrointestinal tract.

Sources of infection: in natural conditions-many types of rodents, as well as domestic animals (pigs, cattle, dogs, etc.). Sick animals and carriers secrete leptospira in the external environment with urine and infect reservoirs, food and household items (rodents).

Transmission routes – contact, water, food.
Infection with leptospirosis occurred when drinking well or spring water, contact with rodents, or bathing in the water of open reservoirs.

Pseudotuberculosis is an acute infectious bacterial disease with a polymorphic clinical picture from scarlet fever, joint damage to food toxicoinfection and septic conditions.

The sources of infection are different types of rodents.

Pathogen: a bacterium that persists and multiplies for a long time in the external environment and food products (vegetables, fruits, milk, etc.), even in cold conditions.

The transmission routes are food (through infected products) and contact.
The most significant factors of transmission of infection are food products consumed without heat treatment, which often leads to outbreaks in organized children's groups, in violation of the rules for preparing and storing dishes from raw vegetables. 

Tularemia is an acute bacterial, natural focal infection. The clinical picture is characterized by the appearance of unilateral lymphadenitis, conjunctivitis, angina. The form of the disease depends on the place of penetration of the causative agent of tularemia into the human body.

Pathogen: a bacterium.

Sources of infection: small mammals (rodents and hares, which infect the environment, food, household items with their secretions).

Carriers: blood-sucking arthropod insects (mosquitoes, horseflies).

Transmission paths: vector-borne (bites of blood-sucking insects), contact (infection of intact skin, mucous membranes of the respiratory tract, conjunctiva of the eyes, mucous membranes of the gastrointestinal tract). 

Rabies is an infectious zoonosis of viral etiology, characterized by predominantly severe damage to the central nervous system, threatening death. A person becomes infected with rabies when bitten by animals. Spreading through the nerve fibers, the rabies virus first increases their excitability, and then causes the development of paralysis. Penetrating into the tissues of the spinal cord and brain, the virus causes gross violations in the work of the central nervous system, clinically manifested by various phobias, attacks of aggressive arousal, hallucinatory syndrome. Rabies is still an incurable disease. For this reason, it is difficult to overestimate the importance of preventive anti-rabies vaccination given to the patient in the event of an animal bite.

Tick-borne borreliosis (Lyme-borreliosis, Lyme disease) is a natural focal infection with a vector-borne transmission, caused by three species of spirochetes of the genus Borrelia, which enter the human body when bitten by an ixod mite infected with borrelia. The course of the disease is chronic with repeated relapses.

Source distribution and reservoir of pathogens are domestic and wild animals, birds, rodents-sheep, cows, pigs, dogs, deer, etc.Carriers of infection – ixod mites. The risk of infection with borreliosis increases many times during the tick activity season, which lasts from April to October. These arthropods can get on open skin areas during walks in the park, visiting forests.

A patient with Lyme borreliosis is not dangerous for others. The immunity produced after recovery is short-lived: after 5-7 years, reinfection with tick-borne borreliosis is possible.

Basic measures for the prevention of natural focal infections:

• carrying out the improvement of the territories of suburban areas (clearing of weeds, construction and household garbage) to exclude the possibility of rodent life and contact with rodents
• taking measures to prevent rodents from entering the premises where food products are stored;
• control of rodents and blood-sucking insects, carrying out extermination measures (deratization, disinsection) and disinfection measures in the premises and on the territory before entering the suburban areas;
• the use of repellents against the bites of mosquitoes, horseflies, ticks-carriers;
• when bathing in reservoirs, choose reservoirs with running water, do not swallow water;
• observe preventive measures when walking in the forest (choose a clearing or a bright area of the forest, do not sit in haystacks or straw, store food and water in a closed container);
• observe the technology of preparation and terms of implementation of salads from raw vegetables;
• do not use water from unknown sources for drinking, cooking, washing dishes and washing up;
• use only boiled or bottled water for drinking;
• exclude contact with unknown dogs and cats and wild animals;
• do not pick up dead animals;
• observe personal prevention measures.

Chief Freelance Specialist in Infectious Diseases
health departments of the Lipetsk region,
Volodina Larisa Viktorovna