The main characteristic of natural focal diseases is that their pathogens are transmitted to humans from birds or animals. Typically, transmission occurs through the bites of blood-sucking insects such as mosquitoes. 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 human life, it is important to have information about the ways of transmission of infection and methods of prevention diseases.
What is a "natural hearth"?
The phrase "natural focus" directly indicates that the source of infection exists in nature. Transmissible and natural focal diseases are associated with certain biogeocenoses. The causative agents 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. At the same time, pathogens are transmitted in various ways: through insect bites, by inhalation of dried excrement of infected animals, etc.
Teachings of Academician E. N. Pavlovsky
The doctrine of natural focal diseases of Academician Pavlovsky is one of the most outstanding achievements of biological science.
Pavlovsky's teaching says that on the territory of some landscapes there are foci of diseases that can be transmitted to humans. These centers were formed during the long evolutionary development of biogeocenosis.
A natural focal disease occurs when three links occur simultaneously:
- population of pathogens;
- population of animals that are hosts (reservoirs) of pathogens;
- population of carriers of pathogens.
For example, Pendin's ulcer, common in some parts of Central Asia, belongs to natural focal diseases. The causative agent of the disease is Leishmania. The reservoir of Leishmania is gerbils - small rodents that live in deserts. Leishmania is transmitted through mosquito bites.
Focuses of several diseases can be present in the same area at the same time, which is important to consider when developing preventive measures.
Varieties of natural foci
Natural focal disease can be of two types:
- monovector - only one carrier can take part in the transmission of pathogens from one organism to another;
- multi-vector - transmission can be carried out by several types of carriers.
E. N. Pavlovsky singled out another type of natural foci -anthropourgical. The appearance of these foci is due to human activity and the ability of some carriers to move to a synanthropic existence. Such vectors, such as mosquitoes or ticks, are predominantly found in urban or rural environments, that is, close to human habitation.
Carriers of natural focal diseases
Natural focal infectious diseases can be spread by two types of vectors: specific and non-specific. In the organisms of specific vectors, the causative agent of the disease goes through some of the stages of its life cycle: it reproduces, accumulates, or even turns from an egg into a larva. The pathogen can maintain its vital activity only in the body of a certain carrier, having adapted to it in the process of evolutionary development.
Non-specific carriers move pathogens mechanically. In this case, the pathogen remains for some time either on the proboscis or in the intestines of the distributor.
How can infection occur?
Infection with natural focal diseases can occur in various ways:
- industrial infection is associated with work carried out in or near forest areas, infection can occur during construction or logging work, during the harvesting of flax, vegetables, etc.;
- infection while working at their summer cottage:often rodents that are carriers of infections live in country houses or sheds, infection can occur by inhalation of dried excrement of mice and rats;
- domestic infestation, which often occurs in homes located near forests, is due to the fact that rodents enter barns, cellars or living quarters;
- infection during a short stay in the forest, for example, on a walk or on a hike.
The most common diseases
Tick-borne encephalitis is a natural focal disease characterized by severe intoxication and damage to the brain and spinal cord. Patients develop persistent irreversible neurological disorders, possibly fatal.
Japanese encephalitis - an acute disease that occurs with damage to the brain and its membranes. Japanese encephalitis is carried by mosquitoes. The main symptoms are lethargy, fatigue, speech and vision disorders, fever, chills and vomiting. Lethal outcome is observed in 40-70% of cases.
Rabies is one of the most dangerous natural focal diseases. Signs are anxiety, hypersensitivity to bright light, insomnia, convulsions, rabies. The patient sees hallucinations, becomes aggressive.
FMD is a natural focal disease that affects the mucous membranes, the periungual bed and the folds between the fingers. The pathogen enters the body through food. The onset of foot and mouth disease is quite acute, proceeding with a sharprise in temperature. The prognosis is often favorable, although serious complications may occur in children.
Anthrax is a disease that has two forms: skin and septic. The cutaneous form is characterized by the appearance of numerous ulcers. This form develops rather slowly and responds well to treatment. The septic form is more dangerous, and death can occur in just a few days.
Prevention of natural focal diseases
Pavlovsky's doctrine of natural focal diseases had a huge impact on the approach to prevention. Whereas initially the main measure to prevent epidemics was to treat infected people and destroy vectors such as mosquitoes or ticks, today the main goal is the elimination of animal reservoirs.
In order to protect yourself from natural focal diseases, it is important to follow a number of preventive measures: get vaccinated in a timely manner, do not visit the habitats of animals that are carriers of pathogens, and also protect yourself from insect vector bites with closed clothing or by using special repellents.
