Mosquito virus encephalitis in children

Mosquito, or Japanese (autumn), encephalitis is an acute seasonal neuro-infection with common infectious manifestations and severe damage to brain matter.

ICD-10 code

• A83.0 Japanese encephalitis.
• A83.1 Western equine encephalitis.
• A83.2 Eastern equine encephalitis.
• A83.3 Encephalitis St. Louis.
• A83.4 Australian encephalitis (a disease caused by the virus of Quinjin).
• A83.5 California encephalitis (California meningoencephalitis, La Crosse encephalitis.)
• A83.6 Disease caused by the virus of Rocio.
• A83.8 Other mosquito virus encephalitis.
• A83.9 Mosquito virus encephalitis, unspecified.

Epidemiology

Mosquito (Japanese) encephalitis is a typical natural focal infection. The reservoir of the virus is used by many wild animals and especially birds, the carriers are Sikhs tritaeniorhynonus and other mosquitoes. Infected mosquitoes transmit the virus to a person during a bite with saliva. The disease has a strict summer-autumn seasonality with a maximum incidence in August-September. Usually the epidemic outbreak is preceded by hot weather, which contributes to the mass export of mosquitoes.

All people are susceptible to mosquito encephalitis. Farm workers, as well as older children, are more often ill. Possible group illnesses of children in recreation camps located near the natural foci of infection, near small ponds or in a marshy area.

Classification

Cases with CNS involvement are classified as typical, which, depending on the severity of cerebral and focal symptoms, can be mild, medium-heavy and severe.

To atypical forms of mosquito encephalitis include erased and subclinical forms with abortive course without CNS damage.

Causes of mosquito encephalitis

The causative agent of mosquito encephalitis, as well as the agent of tick-borne encephalitis, refers to arboviruses (the genus Flaviviruses) and represents one of the four antigenic species of this genus. Among the animals, monkeys, white mice, hamsters, rats, etc. Are most susceptible to the virus.

The pathogenesis of mosquito encephalitis

After being bitten by an infected mosquito, the virus enters the CNS in the hematogenous way and, in connection with pronounced neurotropism, multiplies rapidly in nerve cells. When the maximum concentration is reached, the virus re-enters the blood and acts in general, which corresponds to the end of the incubation period and the onset of clinical manifestations.

The greatest morphological changes are found in the central nervous system. Macroscopically the cerebral membranes are edematous, hyperemic, with pinpoint hemorrhages. The substance of the brain is swollen, flabby, with local hemorrhages and foci of softening. Expressed changes are noted in the field of visual tubercles and striatal formations.

Symptoms of mosquito encephalitis

The incubation period is 5-14 days. The disease begins sharply, with a rise in body temperature to 39-40 C, chills, headache, nausea and vomiting.The face of the patient quickly becomes hyperemic, scleritis and catarrhal conjunctivitis are expressed.For the 2-3rd day of the disease, meningeal symptoms appear, and with 3-4 days - symptoms of focal or diffuse encephalitis.The patients are stunned, indifferent, do not react to the examination and the surrounding.Several excitement with delirium, hallucinations and loss of consciousness is noted.As a result of muscular hypertension the patient lies with his head thrown back and brought to life In the defeat of the pyramidal system spasmodic mono-and hemiparesis occur.In the defeat of the spinal cord there are flaccid paralysis.With the spread of the lesion to the boulevard centers, breathing disorders, swallowing, falling of the cardiovascular tone, damage to the motor sphere are possible.This is manifested clinically by various hyperkinesia of muscles face and upper limbs.

In severe cases, tonic or clonic convulsions occur.

Symptoms of mosquito encephalitis also include increased sweating, lability in the cardiovascular system, deafness of cardiac tones, and reduced arthritic pressure.

In the blood determine leukocytosis, neutrophilia with a shift to stab and nuclear forms, lymphopenia, eosinopenia, increased ESR.

With a lumbar puncture, a clear fluid flows out under pressure. Detect a moderate (up to 100-300 cells in 1 μl) lymphocytic cytosis and a slight increase in protein content.

Diagnosis of mosquito encephalitis

The diagnosis is based on a clinical picture of encephalitis or meningoencephalitis that has arisen against the background of common infectious symptoms in a child living in the endemic foci of mosquito encephalitis in the summer or autumn. To confirm the diagnosis, PCR and ELISA are used, as well as virus isolation from blood and cerebrospinal fluid on tissue culture or by infecting newborn mice in the brain, followed by virus identification with serological reactions. The detection of the growth of specific antibodies in paired sera of patients in RN, RSK, RTGA, etc. Is of diagnostic significance.

Treatment of mosquito encephalitis

In the early stages of mosquito encephalitis it is recommended to administer a specific immunoglobulin from the calculation of 0.5-1 ml / kg per day in 2-3 doses. Pathogenetic and symptomatic therapy is the same as in tick-borne encephalitis.

Forecast

The prognosis for mosquito encephalitis is serious. Mortality reaches 25-50%. With a favorable outcome, persistent residual events are possible in the form of a decrease in intelligence, psychosis, psychasthenia. However, unlike the tick-borne encephalitis of a long progredient course with the formation of persistent hyperkinesis or epileptiform seizures with mosquito encephalitis does not happen. The recovery period, as a rule, proceeds relatively safely. With the disappearance of the symptoms of general infectious toxicosis, the consciousness of the patients clears up and the focal symptomatology gradually decreases. The recovery period is 0.5-2 months; at this time, mental abnormalities, hemiparesis, vegetative disorders, muscle weakness, unsteadiness of gait and other manifestations of the disease.

Prevention of mosquito encephalitis

The fight against mosquitoes - vectors of the pathogen and the creation of active immunity in the population living in endemic areas. Immunization is carried out with the killed vaccine. For emergency prevention, a single immunoglobulin is administered once in a dose of 0.2 ml / kg.

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