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Leptospirosis

Leptospirosis is a group of acute infectious diseases caused by leptospirae and characterized by similar clinical and epidemiological data. The most common forms of leptospirosis are: Vasiliev – Weil's disease (see) and water fever (see).

Etiology . Leptospirosis pathogens are different types of leptospira, morphologically similar and similar in antigenic structure. Leptospira are thin, movable spirals with mild curls. The natural habitat of leptospira is the animal organism. In reservoirs, leptospira are able to remain active for up to 30 days. When heated to t ° 50-56 ° they die for 25 minutes; quickly die under the influence of disinfectant solutions. In the USSR, the most common and best studied are leptospira: L. grippotyphosa, L. hebdomadis, L. nero, L. ussuri, and others. The epidemiological significance of certain types of leptospira is different.

Epidemiology . The source of Vasiliev-Weil disease is rats. Workers of slaughterhouses, food warehouses, fisheries, mines , as well as vacuum trucks, plumbers, etc., get sick more often. The disease is spread by the type of intestinal infections. The overwhelming majority of people become infected by drinking infected water.

The source of water fever infection is rodents-voles, as well as cattle, pigs, dogs. Sick animals secrete the pathogen with urine, which can be contaminated by water, soil , food, etc. The disease spreads mainly through the water of standing water when bathing, as well as using it for drinking and domestic purposes. Infection is possible when mowing wetlands, harvesting rice, sugar cane, processing raw materials, as well as consuming infected milk. Leptospirosis occurs in the form of outbreaks in the summer-autumn period and sporadic cases throughout the year. The postponed disease leaves a durable and long-lasting specific immunity.

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The pathogenesis of all leptospirosis is very similar: it is based on damage to the liver, kidneys, blood vessels (mainly capillaries) and the central nervous system. Leptospira enter the body through damaged skin and mucous membranes of the oral cavity, esophagus , eye conjunctiva, and there are no inflammatory phenomena at the site of penetration. 3-5 minutes Leptospira penetrate the blood, where they are found until the 5-6th day of illness, and then only in the tissues of the organs, especially in the kidneys and liver, where their rapid reproduction occurs . In the liver, leptospira cause degenerative and necrotic changes. The origin of jaundice is due to damage to the liver parenchyma and to a lesser extent - the destruction of red blood cells . From the 2nd week, leptospira are localized almost exclusively in convoluted tubules of the kidneys (disappearing from the blood and other organs) and cause impairment of urine formation. The most common cause of death is uremia .

The clinical picture (signs and symptoms). Leptospirosis is divided conditionally into severe forms with high mortality and relatively benign (anicteric). In case of Vasiliev-Weil disease (see Vasiliev-Weil’s disease) jaundice is often observed, the mortality rate reaches 4-8%; water fever (see) occurs, as a rule, without jaundice, fatal outcomes are extremely rare. However, there is no complete relationship between the severity of the disease and the serotypes of the pathogens.

The illness begins acutely. An increase in temperature (up to 30-40 °) is accompanied by chills, headache, pain in the calf and other muscle groups. Further, depending on the severity of the disease, other symptoms join: nausea , vomiting (often mixed with blood), delirium, insomnia , nosebleeds. The temperature remains high for 4–9 days. With a fall in temperature in severe cases jaundice develops, hemorrhages, often hemorrhagic herpes . The liver is enlarged, its palpation is painful. The amount of urine decreases until anuria with the development of uremia. There are recurrences of fever. The most common cause of death is uremia (see).

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The clinical picture in benign leptospirosis differs from the severe forms by a more moderate lesion of the vascular system, kidneys and liver. In particular, usually there is no uraemia, jaundice and severe hemorrhagic diathesis. Other symptoms are similar or coincide with those observed in severe forms.

Laboratory diagnosis . For the detection of leptospira in the first week of the disease, blood is sown, in the second to third week, urine and cerebrospinal fluid are cultured on special nutrient media . From the 2nd week of illness, serological reactions (agglutination and lysis) are performed.

Differential diagnosis should be carried out with the flu (see), typhoid fever (see), typhus (see), mosquito fever (see), epidemic hepatitis (see).

Treatment . Hospitalization, bed rest, milk-vegetable diet and heavy drinking are obligatory.

When headache and muscle pain prescribed amidopyrine 0.5 g 3 times a day, analgin 0.5 g 3 times a day. Cardiovascular agents are shown.

Antibiotics are effective if used early; prescribed in standard doses. In severe cases, penicillin is injected intramuscularly at 900,000-1,500,000 units per day, as well as gamma globulin .

Prevention is based on the extermination of rodents - sources of infection - and other activities, as with intestinal infections. According to epidemiological indications, vaccination of people is applied. The vaccine is injected subcutaneously in a dose of 2 ml twice, the interval between injections is 7 days.

Leptospirosis (leptospiroses) is a group of acute infectious diseases, similar in clinical manifestations, pathogenesis, pathology, epidemiology, and epizootology. Sporadic cases and epidemic outbreaks in humans and domestic animals are described in almost all countries of the world.