Foot and mouth disease

Foot and mouth disease (synonym stomatitis epidemica, aphtae epizooticae, Rylko-hoof disease), acute infectious disease of viral etiology, transmitted to humans from infected animals and characterized by fever, education aft on the mucous membrane of the mouth, tongue, nose, and between the fingers and the nails.
Etiology. The causative agent of FMD small virus value 20-30 MMK, belongs to the family of picorna viruses. There are 8 serological types of FMD virus. The virus is not very sensitive to the action of alcohol, ether, chloroform; quickly perishes under the influence of formalin, caustic soda.

The causative agent of FMD - small, containing RNA virus belonging to the family of picornaviruses (type Picornavirus aphthae).
The amount of virus 20-30 MMK. The virions have a hexagonal shape, the exact number of capsomeres unknown. Selected 8 serological types of virus (a, C, S AT I S AT II'S AT III, Asia I, Asia II), each of which includes 3 to 15 antigenic variants.
The FMD virus is well preserved in the bodies of dead animals and in dried form; not sensitive to the action of alcohol, ether, chloroform and desoxycholate. Quickly destroyed by the formalin and caustic soda.
In natural conditions the virus high contagiosum for cattle, pigs; less for sheep, goats, and other ungulates. Of laboratory animals susceptible to the virus rabbits, Guinea pigs, chickens, chicken embryos, mouse, and to a lesser extent cats and dogs. People become infected by eating virus-containing foods (milk, meat) or after contact with sick animals. The greatest sensitivity to virus differ skin cells language cows, calves, tissue culture kidney calves and pigs.
The virus isolated from the aft, milk, blood, saliva, urine and feces by infecting sensitive tissue cultures, newborn mice (in the brain) or intraperitoneally) or cattle (infection in the language). To identify the virus uses the reaction of binding complement, precipitation and neutralization.
Epidemiology. Foot and mouth disease is observed in cattle, less often in pigs, goats, sheep, deer, camels, Buffalo, yaks, and others Rarely get sick horses, dogs, pigs, cats. Especially frequently and seriously ill young animals. In cattle sometimes there is a malignant form of foot and mouth disease, which leads to death through 1-1 .5 hours to 60% of the animals. The causative agent is allocated sick animals with the saliva, milk, urine, the contents of the intestines. Milk infected even before the aft and preserves this property to 10-12-th day of illness. Gain popularity saliva stops on 10-11-day and animal disease. This period is determined by the duration of the quarantine. Animals infected with the mutual contact pastures, in barns, stables. The infection is transmitted through contaminated objects (litter, fodder, manure, troughs, water and so on), clothing milkmaids, shepherds and so on Infected wool retains gain popularity up to 1 month. Clothing milkmaids, shepherds etc., may also be a factor of transmission. Carriers of infection are susceptible rodents (squirrels, rats, mice), as well as the gadfly. Birds without diseases FMD can allocate through the intestine introduced to food virus.
In animals, the disease is accompanied by a rash of bubbles (aft), which later izyaslau. Localized afty on the mucous membranes of the mouth, nose, tongue, gums and lips, megapath cracks at the base of the horns on the udder. Characterized by excessive salivation.
A person infected with foot and mouth disease at a nursing animals, in contact with infected objects, often by drinking raw milk products, especially raw milk from infected animals. Boiling and pasteurization of milk pathogen die. In skisystem milk, yogurt, acidophilus milk, yogurt, cottage cheese and butter made from raw milk of infected animals, the virus persists for a short time. These products are rarely the cause of the disease people. Most FMD susceptible children. Transmission from person to person is not observed.
Pathogenesis. Entrance gate of infection is the mucous membrane of the mouth, rarely mucous membrane of the upper respiratory tract. In place of introduction of the virus causes the formation of specific afty (see), filled with serous exudate. At the end of the incubation period are exposed to mechanical reasons AFTA is broken, and the virus enters the blood stream. There comes the first stage of the disease (generalization of the process). Hematogenous by the agent, with the strong epitheliotropic reaches of the mucous membranes of the mouth, lips, tongue, nose, throat, where do multiple secondary atty. The second (septic) stage of foot and mouth disease is accompanied febrile response, chills, the advent of the aft on the skin. From the blood flow the virus enters the excretory-secretory organs and out from the body with the saliva, bile, milk, urine and faeces.

Pathological anatomy. In a basis of formation of the aft with FMD are necrobiotic changes epidermal cells. First in deep layers of the epidermis arise pockets dystrophy - swelling and swelling of the cells with eosinophilic homogenization of cytoplasm, with the dissociation of cellular elements. Formed small single-chamber vials.
Pathological anatomy of the foot and mouth disease in humans has not been studied enough. Described focal necrosis of the skin and mucous membranes of the gastrointestinal tract, trachea, urethra. Characteristic of surface pitting, lymphohistiocytosis infiltration with poor mixture of polymorphonuclear leukocytes. Celebrate the enlargement of heart, flabbiness and clay view of the heart muscle. Microscopically find focal alterative changes in the form of protein and fatty degeneration of the muscle fibers, swelling and lymphohistiocytic infiltration stroma. Described cases cloudy swelling and fatty degeneration in the hepatic parenchyma, kidneys and muscles.

foot and mouth disease
Foot and mouth disease. Fig. 8. Afty on the mucous membrane of the lower lip.

The clinical picture. The incubation period of 3 to 8 days. The disease starts acutely. During the first two days worsens the General condition, the temperature rises to 40 degrees, you receive chills, asthenia, headache, tachycardia, lowering blood pressure. From the first hours occurs pain mucous membranes of the oral cavity, a burning feeling in the mouth and on the tongue, muscle aches and back pain, profuse Department frothy saliva. The mucous membrane of the oral cavity, pharynx, tongue, nose and lips bright garmirian, swollen. The rash lasts for a week. Afty located in the mucosa of the mouth, throat, tongue, cheeks and lips, less often on the mucous membrane of the vagina and conjunctiva. Afty have the elliptic form and consist of bubbles size from 1 to 3 mm (Fig. 8). Bubbles contain serous fluid, which soon becomes pussy. After 1-2 days thinned walls of bubbles burst, forming a small surface painful sores, often merging with each other. Especially many primary aft on the edge and the tip of your tongue. The patients dysphagia, speech disorder, swelling of the tongue. On the wounded attach formed yellow or black (hemorrhagic) peel, not welded with the underlying tissues. Salivation may reach 2 l per day. Submandibular lymph nodes priuchayut and become painful. In the result of viraemia are formed secondary afty with the same evolution of bubbles. They are located on conjunctiva, the skin of the upper arms, hands, legs, feet. The preponderance of skin folds between toes and nails, forced posture of the patient, fingers spread. Sometimes there is a generalized exanthema, especially in the field of distal limbs, combined with recurrent aphthous lesions. In such cases, the disease takes a protracted course. When localizing the aft the external opening of the urethra patients complain of feeling pain and burning during urination. Depending on the location of ulcers observed forms of skin and mucous membranes, gastrointestinal with symptoms of gastroenteritis, pulmonary (traheobronhity, bronchopneumonia). With rare forms of heart death comes to the appearance of lesions in the result of degenerative changes of the myocardium. The eruption of the aft there is sometimes only in the area of the entrance gate infection - local FMD" with a light within. The duration of febrile period is 4-6 days. Often the disease is delayed because of current evidence. At the end of incubation in the blood - moderate leukopenia, eosinophilia.
In milder forms of foot and mouth disease, the prognosis is good. Recovery occurs in 10 to 15-th day from the onset. In severe forms of the death results from heart failure, pneumonia, gastroenteritis. Transferred disease leaves a strong immune system. Complications are a result of stratification other infections (Whitlow, furunculosis, septicemia, pneumonia, and so on).