Zoonoses
The content of the article:
- Causes and risk factors
- Forms of the disease
- Symptoms
- Diagnostics
- Treatment
- Possible complications and consequences
- Forecast
- Prevention
Zoonoses are infectious diseases transmitted from vertebrates to humans. Modern medicine knows about 200 nosological forms belonging to this category, about 30 zoonotic infections are significant for humans.
Zoonoses are a group of infectious diseases transmitted from animal to human
Zoonotic infections pose a serious social and economic problem for a number of reasons: ubiquity, wide species diversity, numerous populations of domestic and stray animals as potential carriers of parasites, etc.
In a zoonotic infection, the animal plays the role of a natural reservoir - a long-term host, in whose body the parasite that causes the disease can exist for a long time without interrupting the life cycle. An animal can either "overdo it" or be an asymptomatic carrier, a transporter of the causative agent of one or another zoonosis. A person is usually a dead-end branch for the causative agents of zoonoses, the cycle of development of the parasite is interrupted on him, nevertheless, the parasite can cause disease.
The main characteristics of zoonotic infections are:
- the absence of specific mechanisms of transmission of diseases from person to person, as is possible in animal communities;
- concentration of the bulk of cases of infection in a limited area in the focus of infection (circulation of the disease without drifting from the outside);
- minimal or complete absence of human excretion of pathogens into the environment.
Over the course of several years, the World Health Organization registered about 70 unpredictable outbreaks of infectious diseases, more than half of which fell on dangerous or especially dangerous zoonoses. Recently, the range of such diseases has expanded significantly due to active migration processes and the circulation of infectious agents uncharacteristic for a particular territory.
Causes and risk factors
The main causes of diseases are:
- microorganisms that develop up to a certain stage in the internal environment of the animal, and then enter the human body;
- arthropod insects with direct damaging effects.
Groups of pathogens provoking zoonoses:
- prions (infectious agents represented by abnormal pathogenic proteins);
- viruses;
- protozoa;
- bacteria;
- mushrooms;
- helminths;
- arthropods (ticks, fleas, arachnids, etc.).
There are several mechanisms for the transmission of the pathogen from a permanent host to an intermediate:
- fecal-oral, carried out when drinking water or food contaminated with the feces of an infected animal (brucellosis, salmonellosis, leptospirosis);
- transmissible (blood), when the pathogen is carried by a blood-sucking insect (plague, tularemia, encephalitis, hemorrhagic viral fevers, yellow fever);
- direct transmission with localization of the pathogen in the skin, mucous membranes, salivary glands of the animal (rabies, glanders, anthrax).
Zoonoses are transmitted through direct human-animal contact
Infection occurs under the following circumstances:
- bite, scratch caused by animals, insects, birds;
- drinking water or food contaminated with the pathogen;
- inhalation or accidental ingestion of microparticles of wool, skin of an infected animal or bird;
- eating meat or milk of a sick individual.
Risk factors for contracting a zoonotic infection:
- consumption of untreated drinking water, contaminated fruits, vegetables;
- direct contact of the skin with the ground (walking without shoes, being on the grass without a cover, playing with sand, etc.);
- tactile contact with animals, birds;
- neglect of personal hygiene measures;
- long-term stay in places where blood-sucking insects accumulate (in swampy and wooded areas, on edges with dense grass cover, etc.);
- stay in the focus of infection.
Forms of the disease
Depending on the type of pathogen, the following forms of zoonoses are distinguished:
- prion infections (Creutzfeldt-Jakob disease, transmissible spongiform encephalopathy);
- viroses [rabies, SARS (atypical pneumonia), foot and mouth disease];
- chlamydia and rickettsioses are diseases caused by obligate intracellular parasites, corresponding bacteria [Q fever, psittacosis];
- bacteriosis (anthrax, brucellosis, leptospirosis, salmonellosis);
- mycoses (dermatophytosis);
- protozoses (amebiasis, toxoplasmosis);
- helminthiases (ascariasis, echinococcosis);
- arachnoentomoses (myiasis).
Taking into account the types of life cycles and the nature of the transmission of pathogens, the structure of parasitic systems and other ecological and epidemiological signs, several groups of zoonotic infections are distinguished:
- directzoonoses are typical diseases characterized by direct or indirect contact transmission of the pathogen from an animal to a person (rabies, myiasis);
- cyclozoonoses, in the development of which more than one species of vertebrates (intermediate hosts) is involved (echinococcosis);
- metazoonoses - in this case, invertebrates are the carrier of the infectious agent from animal to human, the transfer is carried out transmissively (borreliosis, schistosomiasis);
- ornithozoonoses - diseases for which the main hosts are birds, human infection can be carried out both through direct contact and through blood-sucking invertebrates (psittacosis, bird flu);
- saprozoonoses - a group of diseases for which causative agents are natural habitats of inanimate objects (soil, water), as well as food (anthrax, tetanus, botulism);
- phytozoonoses - factors of the plant environment (food and opportunistic infections and mycoses, such as yersiniosis, listeriosis) serve as a reservoir for their pathogens.
According to the type of animals involved, the following zoonoses are reported:
- with the participation of domestic and synanthropic (living close to humans and related) animals and birds;
- with the participation of wild animals (natural focal zoonoses).
Symptoms
Symptoms of zoonotic infections are varied, individual in each case and can manifest themselves in almost any organ system:
- dyspeptic disorders (nausea, vomiting, pain in the umbilical or epigastric region, bloating, diarrhea, decreased or complete lack of appetite);
- deterioration of general well-being, decreased tolerance to habitual physical activity, disturbance of sleep and wakefulness, asthenia, increased body temperature, chills, torrential sweat;
- headache, episodes of dizziness, seizures, delirium, hallucinations, depression of consciousness, other neurological symptoms;
- lowering blood pressure, tachycardia;
- muscle and joint pain, swelling in the projection of the joints, stiffness;
- skin rashes of varying intensity and character, enlargement and soreness of the lymph nodes, hyperemia or yellowness of the skin, injection, icterus of the sclera;
- enlargement of the liver, dull bursting pain in the right hypochondrium or acute girdle pain; etc.
Dyspeptic disorders are common symptoms of zoonotic diseases
Diagnostics
The following methods can help diagnose zoonotic infections:
- collection of an epidemiological history;
- clinical analyzes of urine and blood;
- blood chemistry;
- sowing vomit, feces, gastric lavage, separated from the foci of inflammation (in the case of generalized infection - blood), etc. on nutrient media in order to determine the pathogen;
- bacteriological examination of food residues, washings from dishes;
- smear microscopy;
- biological diagnostic method (infection of experimental animals);
- indirect hemagglutination reaction;
- polymerase chain reaction;
- linked immunosorbent assay;
- Ultrasound examination of the abdominal organs;
- conducting specific tests with various diagnostics.
Treatment
Complex treatment of zoonotic infections, as a rule, is carried out in a hospital setting:
- etiotropic therapy (antibacterial, antimicrobial, antiviral, antiparasitic drugs, etc.);
- detoxification therapy;
- desensitizing drugs;
- immunostimulating agents;
- symptomatically (if necessary) - antipyretic, non-steroidal anti-inflammatory, glucocorticosteroid hormones, antispasmodics, etc.;
- hepatoprotectors;
- drugs that improve metabolic processes and energy supply to cells and tissues.
Treatment of zoonotic infections includes a wide range of drugs
For some diseases, surgical intervention is required in order to surgically remove the pathogen from the human body.
At the recovery stage, physiotherapeutic procedures are recommended (UHF, quartz treatment, paraffin baths, radon baths), spa treatment, diet therapy.
Possible complications and consequences
Zoonotic infections can provoke the development of a whole range of different complications:
- renal (hepatic) failure;
- inflammation of the organs of the hepatobiliary zone;
- reactive pancreatitis;
- myocarditis;
- arthritis;
- gastritis, gastroenteritis, enteritis, enterocolitis;
- peritonitis, intestinal bleeding;
- glomerulonephritis;
- meningitis, encephalitis;
- swelling of the brain;
- the formation of abscesses of various organs;
- infectious toxic shock;
- multiple organ failure;
- coma, death; and etc.
Forecast
The forecast is individual in each case. The duration and severity of the disease vary widely and depend on the type of pathogen, the method of infection, the individual state of the organism and other factors.
Prevention
In order to prevent infection with diseases from the zoonotic group, it is necessary:
- limiting tactile contact with homeless and synanthropic animals and birds;
- compliance with safety measures with constant professional contact with animals, birds;
- refusal to eat meat and dairy products that have not passed compulsory certification (purchased in spontaneous markets, "off hand", in unlicensed retail outlets);
- boiling water, pretreating fruits and vegetables before eating;
- compliance with personal hygiene measures;
- the use of repellents for the expected long stay in places where insects accumulate;
- vaccination and regular veterinary control of pets;
- carrying out disinsection and deratization in personal plots and in residential premises.
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Elena Minkina Doctor anesthesiologist-resuscitator About the author
Education: graduated from the Tashkent State Medical Institute, specializing in general medicine in 1991. Repeatedly passed refresher courses.
Work experience: anesthesiologist-resuscitator of the city maternity complex, resuscitator of the hemodialysis department.
The information is generalized and provided for informational purposes only. At the first sign of illness, see your doctor. Self-medication is hazardous to health!
