Epidemic typhus

Related articles:

• Typhoid
• Tick-borne typhus

What is typhus?

Typhus is anthroponoses vector-borne infectious disease caused by Rickettsia, pathogenetic basis of which is the defeat of the microcirculatory vasculature and internal organs on a background of the expressed intoxication symptoms and characteristic skin rash. Each of the terms of this definition requires separate consideration.

The term anthroponoses disease means that infectious agents, which if typhoid typhus are Rickettsia circulate only in human populations and are transmitted from person to person. The participation of animals as a reservoir for the life cycle of the causative agents of typhus is not required.

Vector-borne disease. This means that the transmission of typhus through the bites of vectors of pathogens. These are all types of lice (head, pubic, wardrobe). After the bite of a sick person in the digestive tract enters the blood lice with Rickettsia. Here is their intermediate cycle of life. Infected lice, getting to a healthy person, defecate on his skin, then carry out the sting. By brushing and rubbing infected with Rickettsia, stool, occurs the penetration of pathogens into the bloodstream with subsequent dissemination throughout the body.

The Central link of pathogenesis when typhus typhoid are disorders of microcirculation. They are based on the high affinity of the Rickettsia to the endothelium. To a greater extent marvel ultimate branches of the arterial system – capillaries and small arterioles. The primary cycle of reproduction of the pathogen occurs in the lymph nodes. This time is called the incubation period. At the end of Rickettsia increases so much that the lymph nodes are not able to keep them. As a result, a massive release of pathogens into the blood system diversity on the microcirculatory bed of all organs and tissues.

The intoxication symptoms of the disease are associated with the periodic occurrence of bacteremia. This periodcorresponds to the time of the release of rickettsiae from the lymphatic system. Thus there is a massive immune response, leading to activation of phagocytic activity of blood. Destroyed pathogens are a powerful source of toxins and cause severe intoxication.

The defeat of the internal organs and skin have the same origin – microcirculatory disorders. Their cause is the spread of Rickettsia in endothelial cells after release into the blood. Because the owners of the most extensive capillary network are the heart, brain, kidneys, intestines, lungs and skin, and they act as target organs in typhus fever. Disruption of their structure and function is caused by inflammation in the vascular wall, their pathological dilatation, thrombus formation and cessation of blood flow.

The symptoms of typhus

In the incubation period of the pathogen, generally, any manifestation occurs. In its last days, perhaps the rise in body temperature, General weakness and malaise. Expanded the clinical picture in typhus typhoid is quite diverse and is characterized by the symptoms that are listed in a table.

Hyperthermia and fever	The increase in body temperature to subfebrile figures at the end of the incubation period (up to 38.0°C); Wavy periodic increase body temperature to a hectic indicators (40°C) during the height of the disease;
Skin rash and lesions of mucous membranes	Small dotted rash rozarenova character in obolochechnykh and armpits. Appear 2-3 days after the occurrence of hyperthermia and mark the beginning of the peak of typhus; Hemorrhagic rash of small diameter (up to 1 cm) on a background of mottled rash covering the chest and abdomen. Talks about the progression of the disease; Conjunctival hyperemia with a congestive vascular pattern and petechial haemorrhages on the type of petechiae (symptom of Chiari-Avtsyn); Reinforced capillary pattern the posterior pharyngeal wall, with its hyperemia and petechial rash (a symptom of Rosenberg-Vinokurov); Short-term tourniquet on the limb cause sharp cyanosis, with the appearance of characteristic spots in the field of future eruptions (symptom DECA) orhemorrhagic rash (symptom Konchalovskogo-Tiller-LEED); If you pinch the skin of the forearms or shins, this leads to the appearance of petechial hemorrhaging (test Jurgens)
Intoxication	Pain in the muscles and bones; Severe General weakness and malaise; Chills; Sweating; Puffiness of face with feverish eyes; Nausea and vomiting.
Damage to the nervous system	Headache and dizziness; Violation of coordination of movements; Meningeal symptoms; Lethargy and dizziness different degrees; Hallucinatory syndrome; The impossibility of extension of the tongue from the mouth (symptom Govorov-Godele)
Damage the heart and lungs	Heart pain and symptoms endocarditis; Tachycardia and arrhythmia; The decrease in blood pressure;
The lesions of the abdominal organs and kidneys	Abdominal pain; Enlarged liver and spleen (hepatosplenomegaly); Signs of intestinal bleeding; Decreased urine output up to anuria.

The causative agent of typhus

Typhoid is caused by the pathogen called Rickettsia of Provasca. These pathogens represent a rod-shaped microorganisms with aerobic type of activity. For their life cycle need the tank, which is a digestive system of lice.The circulation of the pathogen occurs exclusively among the human population at the time of the outbreak. In this regard, a disease that cause the Rickettsia of Provasca called epidemic typhus. The peak of the reproduction and circulation of the pathogen occurs in war time, when progress unsanitary conditions.

The incubation period of Rickettsia after exposure lasts 1 to 3 weeks. They do the blood is contagious for several days of incubation, and after the cessation of febrile symptoms. Toxic properties of this species of Rickettsia due to their parasitism and reproduction is not on the surface of cells, and inside that leads to their destruction with the release of a young bacteria in the blood. The presence in the structure of ricketsia thermolabile, thermostable protein antigens and toxic substances with the properties of endo-and exotoxin provides toxic effects and the rapid response of the body to their excess in the blood.

Prevention of typhus

Preventive measures in epidemic typhus typhoid boil down to:

1. Isolation of sick people with their compulsory hospitalization in infectious hospital;

2. The vector control of the disease in the outbreak of the epidemic;

3. Execution of hygienic procedures in the proper amount;

4. Sanitization of all contact with sick individuals watching them for three weeks;

5. Emergency chemotherapeutic antibiotic prophylaxis with doxycycline all temperaturewhich persons who were related to patients with typhus;

6. Vaccination against typhus weakened vaccine in epidemic foci with the appearance of new cases.