Rat Bite Fever (Sodoku)

What is a Rat Bite Fever (Sodoku)?

The rat bite fever (rat bite disease, sodoku, streptobacillus, Gawheril fever) are two clinically similar diseases (Sodoku and streptocillis pylori, or Gawkerhill fever), characterized by recurrent bouts of fever, accompanied by isothers, and I am afflicted by me, and I will be exhausted, and I will be exhausted, and I will be exhausted, and I will be subjected to issthm, and I will be exhausted, and I will be accompanied by Iferendry, and I will be exhausted by the rash of rats. .

Causes of Rat Bite Fever (Sodoku)

The rat bite fever is caused by one of two pathogens: Streptobacillus moniliformis, a small polymorphic, gram-negative aerobic bacillus, or Spirillum minus, a short elastic spirochete with terminal flagella.

S. moniliformis is an aerobic, immovable gram-negative bacterium that, during growth, forms chains consisting of spindle-shaped microbial cells. When blood is sown, usually on the 2nd-7th day, growth appears in the form of typical colonies resembling a rain mushroom. Often, stable L-forms of the microorganism are formed spontaneously.

The nasopharynx of rats serves as a natural reservoir of S. moniliformis, which stand out in almost half of these animals. In humans, the infection usually develops after the bite of wild rats, after the bite of laboratory rats, which can be carriers of large quantities of this pathogen, and sometimes even after the bite of other rodents. Infection can also be caused by eating contaminated food. The epidemic in Haverhill (Massachusetts) in 1926, during which 86 people fell ill, was caused by the consumption of contaminated milk or ice cream. It gave rise to the term Haverhill fever if the infection is of food origin.

Spirillum minus is a short, thick, spiral-shaped gram-negative microorganism ranging in size from 2 to 5 microns with 2-5 curls and a terminal flagellum, due to which its total length reaches 6-10 microns. Microscopic examination in a dark field reveals a bacterium due to characteristic spasmodic movements and swift movements of the flagellum. A microorganism can be detected by staining blood products obtained from a sick person or animal according to Wright. On artificial nutrient media, it does not grow and it can only be excreted from patients by infecting laboratory animals.

In natural reservoirs, the pathogen carrier state among wild rats reaches 25% of the population. In rats, it causes interstitial keratitis and conjunctivitis. In humans, S. minus infections are almost always the result of a rat bite.

Pathogenesis during Fever from Rat Bite (Sodoku)

The introduction of the pathogen into the body occurs through damaged skin; further, the infection moves along the lymphatic pathways with the formation of lymphangitis and lymphadenitis. At the site of the introduction of a primary affect. Then the pathogen enters the bloodstream, is hematogenously introduced into the organs of the reticuloendothelial system, where it is fixed and causes a repeated generalization of the infectious process (repeated attacks of the disease).

Symptoms of Fever from rat bite (Sodoku)

The incubation period for a rat bite fever with an infection caused by S. moniliformis is short, less than 10 days, usually 1-3 days, but sometimes it can take up to 22 days. The disease develops suddenly and is manifested by fever, chills, headaches, and myalgia that make up the initial complex of clinical manifestations. The bite site is usually not changed, but sometimes swelling, ulceration and regional lymphadenopathy may occur in this area. Approximately 75% of cases with a disease develop a macular rash, which usually appears 1-3 days after the onset of the disease and is most pronounced on the extremities, and the feet and palms can also be affected. The rash may be generalized petechial, itchy, or pustular. During the first week of the disease, approximately 50% of patients develop arthralgia or arthritis, usually characterized by multiple asymmetric involvement of large joints in the process. If untreated, the disease can last for several weeks with persistent or recurring fever and arthritis. Complications of S. moniliformis infection include endocarditis and localized soft tissue or brain abscesses.

For infections caused by S. minus, the incubation period is longer and is usually from 1 to 4 weeks, with fluctuations from 1 to 36 days. The bite site for this infection, as a rule, after the initial healing by the time of the onset of the general disease, becomes edematous, painful and hyperemic. Often develop lymphangitis and regional lymphadenopathy. Fever is usually recurrent in nature with periods of febrile temperature of 2 to 4 days, with intermittent afebrile periods of the same duration. Periods of fever are accompanied by headaches, photophobia, nausea and vomiting. Complications of the joints are rare. The rash is observed in more than 50% of patients and is manifested by macular reddish-brown or purplish-red skin rashes with typical localization on the extremities. If untreated, this recurrent disease can be maintained for months. Occasionally bacterial endocarditis develops.

Diagnosis of Rat Bite Fever (Sodoku)

If there is a history of a rat bite, the main clinical signs that differentiate S. moniliformis infection from S. minus infection are differences in the incubation period, the condition of the bite site, the nature of the fever, and the presence or absence of symptomatology of the joints .

S. moniliformis can be isolated from blood, lymph and tissue taken at the site of the bite, when sown on appropriate nutrient medium or infected laboratory animals. Cultivation of this microorganism requires special conditions; therefore, laboratory personnel should be informed that fever after a rat bite is suspected. S. minus is not detected on artificial media. The pathogen can be detected in blood smears with dark-field microscopy or in Wright-smeared smears. S. minus can be isolated from blood, lymph nodes and local lesions by intra-abdominal infection of mice or guinea pigs.

In infections caused by S. moniliformis, the number of leukocytes is increased, neutrophilia and elevated levels of immature forms are noted. The pathogen can be isolated from blood, joint fluid or pus. A positive serological response is detected by the agglutination test from the 2nd week of the disease.

When infection is caused by S. minus, the number of leukocytes in the normal range or slightly increased. If a disease is suspected, blood should be introduced into the abdominal cavity of a mouse or guinea pig. After 5-15 days, the pathogen can be detected by examining an experimental animal in the dark field of the blood or peritoneal fluid. Approximately 50% of patients revealed biological false positive samples for syphilis.

Treatment of Rat Bite Fever (Sodoku)

When fever after a rat bite caused by any pathogen, it is necessary to inject intramuscularly procaine penicillin (20 000-50 000 U / kg per day) for 7-10 days. Patients who are sensitized to penicillin can be given tetracycline (with the exception of children under 9 years of age), chloramphenicol or streptomycin. Patients with endocarditis should receive penicillin V intravenously 150,000-250,000 U / kg per day in divided doses for at least 4 weeks. Its combination with streptomycin is useful, especially at the beginning of treatment.

Isolation of the hospitalized patient. Precautions are not recommended.

Forecast. In the absence of etiotropic therapy, mortality was from 6 to 10%. With modern therapy, the prognosis is favorable.

Preventing Rat Bite Fever (Sodoku)

For rat bites, prescribe tetracycline (0.25 g 4 times a day for 5 days).

Persons who have been in contact should be supervised. Requires the destruction of rats.