Full information about the transmission and spread of plague

The route of transmission of plague rodents

Plague is a disease of ancient and legendary, but it remains relevant today. Features of distribution and modes of transmission make it practically impossible to complete the destruction of the natural foci of infection and, therefore, the basic method still remains the containment of their control, and rapid response to the emergence of local outbreaks. And to conduct this work most effectively, it is important to understand the mechanism of development and spread of the disease.

The main route of transmission of plague

This disease belongs to zooantroponoznyh infections – it is able to infect not only humans but also rodents, predators, and even insects. The standard transmission is as follows: fleas feed on infected animals and transmit the bacteria to a healthy animal or human.

Of the animals most susceptible to disease rodents: wild (ground squirrels, marmots, voles, pikas, chipmunks, and many others), Pets (rabbits) and commensal (black and brown rats, mice). But also can be infected with other species: foxes, cats and, strangely, the camels. Most farm animals and dogs are not sensitive to this disease, but can serve as carriers of infected insects.

The affected animal after a time dies, but during this time manages to infect blood-sucking insect parasitic on it. From animal to animal plague is transmitted primarily through blood-sucking insects, fleas, and sometimes ticks and bedbugs.

Infected fleas plague a so-called block – tube of bacteria and their waste products in the esophagus. Because of this she can't swallow drinking the blood and spits up after feeding it together with a large number of bacteria. Microscopic wounds on the skin from a flea bite is enough bacteria get under the skin and begin to multiply.

flea

Infected flea dies soon enough, but because of the constant hunger actively moving, infecting new animals and people.

The speed of propagation of the disease is higher in cities with a large number of people and poor hygiene, plenty of rats, and parasite on them, fleas. It has become one of the causes of devastating epidemics in the middle Ages.

Alternative routes of transmission of plague

In addition to the classical scheme of "rodent-flea-man", there may be additional ways of distribution:

  • Directly from an infected animal. Contact with contaminated hides, carcasses, meat dangerous when the presence of the skin microscopic damage that is almost everyone. High risk of infection after bites by infected animals. It is also dangerous consumption of meat and milk, not the last heat treatment.
  • Contact with infected tissues and fluids of the sick person. In the first place, the dangers are doctors, and laboratory staff working with cultures of the plague, and tissues of sick people.
  • Airborne droplets. One of the forms of disease plague pneumonia, in which a large number of bacteria released into the environment with a cough. This is the path of transmission from person to person alleged to have caused one of the three most large-scale epidemics.

Depending on the transmission path, to develop different forms of the disease. In contact with the pathogen directly into the blood or under the skin – bubonic, in rare cases sepsis, with respiratory – pulmonary. The latter can also be a complication more common bubonic.

The epidemiology of plague

Today when there are effective treatments and control the spread of the disease, major epidemics of plague are rare. But in nature there are many epidemiological foci.

As a rule, large colonies of rodents, located in the steppe and lowland areas. These reservoirs are present in almost all continents, then clean area of Australia and Antarctica.

Natural plague foci exist in many countries, including: China, Vietnam, Kazakhstan, Mongolia, USA, Peru, Tanzania, Congo, Madagascar, and Russia. In these countries almost every year to register the cases of the disease. Just a list of countries with unfavourable epidemiological situation includes about 20 States.

The situation with the plague in Russia is quite complicated. In some regions there are natural reservoirs, but until recently, cases were not. The only exception was the incident that happened in July 2016, when the hospital in the Altai region received a child with signs of bubonic plague. As it turned out, he helped his grandfather to skin the carcass of a Groundhog, despite the strict prohibition of hunting on these animals because of the potential threat of infection. The flash managed to be localized quickly, and this case was the only one.

BesidesAltai territory, regions of high threats included, Dagestan, Astrakhan oblast, Karachaevo-Cherkasskaya and Kabardino-Balkar, the Ingush and the Chechen Republic. In the latter two regions there is no permanent control of foci, which is a major concern of epidemiologists. Only the regions with higher probability of infection is about 250 thousand square kilometers and population of about 20 thousand people.

Risk group

Even in potentially dangerous areas, not all people are exposed to similar risks. Considering the propagation mechanism, it is possible to identify the most vulnerable groups:

  • Hunters.
  • Collectors of animal raw materials.
  • Those carrying out disinfestation and deratization.
  • Agricultural worker.
  • Doctors, biologists, epidemiologists, laboratory workers.
At high risk of exposure to people belonging to risk groups should undergo routine vaccination. For the rest of the population, it is not mandatory.

Mass vaccination is not effective as prophylaxis. Existing vaccines against plague give protection only for a year, and to eliminate reservoirs of infection is not possible. Repeat the vaccination every year with a relatively low chance of being infected, is not considered appropriate. Therefore, vaccination is only recommended for risk groups.

Epidemiological events

Knowing the causes and mechanisms of occurrence of epidemics, doctors can quite successfully control them.

The biggest challenge is the isolation of all persons with confirmed diagnosis, as well as everyone with whom they came in contact with lately. This is necessary because the medium is long time to not even suspect that it is infected. The incubation period for the different methods of infection can vary from 1 to 12 days. During this time, the disease may spread widely, because the person is a carrier theoretically could even go to another country.

The difficulty is that the media may be unaware of the infection, so it is important to detect all infected people. To do this, they temporarily isolate and carry out the Express diagnostics.

Asymptomatic carrier, usually harmless, but the disease may endanger his life. High risk for pneumonic forms of plague.

So in India, when the last major outbreak we had to close the borders and set up road blocks to prevent the spread of the plague. But these actions caused panic among the population and led to mass riots.

Medical protocols clearly define the personnel actions upon detection of a sick plague. It must be isolated in the infectious box, all personnel must be disinfected and prevention. All future communication and work is carried out in antiplague suits, and observance of safety measures.

We tried to investigate in detail the ways and reasons of transmission of the plague, and find out who may be carriers of and how dangerous they. I hope that this information will be useful to you.