ENCEPHALITIS MOSQUITO

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ENCEPHALITIS MOSQUITO

(Greek enkephalos a brain + - itis) — the infectious diseases caused by an arbovirus and which are characterized by high temperature, disturbances of consciousness and mental activity, spasms, paresis, paralyzes.

Viruses — activators E. to. — often cause the acute diseases which are shown fever and proceeding without wedge, symptoms of encephalitis therefore nek-ry diseases of this group are called sometimes fevers. E.g., the Venezuelan horse encephalomyelitis (see Encephalomyelitis horse) in some cases is called the Venezuelan horse fever, and the diseases caused by the Western Neil's virus irrespective of prevailing a wedge, symptoms, are often called the Western Neil's fever (see. Tropical mosquito viral fevers).

The diseases entering into group E. to., are heterogeneous; they differ on many signs therefore it is the most reasonable to classify them on etiol. to the principle, dividing (on generic names of activators) into alpha and viral, flavivi-rusny and bunyavirusny mosquito encephalitis. Carry encephalomyelitis of horses and encephalitis of Evergleyds to alpha and viral mosquito encephalitis. Alpha and viral horse encephalitis (encephalomyelitis) — east, western and Venezuelan, similar on a number of signs, usually considers as separate group of mosquito encephalitis (see Encephalomyelitis horse). Carry the Western Neil's encephalitis, Ilheus to flavivirusny mosquito encephalitis, Kunying, valleys of Murray, St. Louis and the Japanese encephalitis. Bunyavirusny encephalitis includes Californian, La Crosse and Tenso.

Among E. to. the greatest value has the Japanese encephalitis representing a serious medical problem for many countries of Asia, other forms E. to. meet less often and have smaller epidemiol. value.

The Japanese encephalitis was for the first time registered in the territory of Japan in 1871. In 1924 observed one of the largest and heavy outbreaks of this disease there (6125 cases, from them 60% ended letalno). The virus is allocated by the Japanese researchers in 1933 — 1936 from different sources, including from mosquitoes of Culex tritaeniorhynchus, to-rye are carriers of a virus.

The disease is eurysynusic in the countries East and Yugo-Vostoch-noy Asia — in Japan, China, in Vietnam, Laos, Thailand, Burma, Malaysia, Singapore, Sri Lanka, India, on the Korean peninsula, on the lake of Taiwan. The disease arises in the form of sporadic cases or flashes. So, in 1958 in South Korea 5,7 thousand cases, 1,32 thousand from are registered to-rykh ended letalno (23,2%). Same year

1,8 thousand cases, from them 519 with a lethal outcome (28,8%), were registered in Japan. In 1961 there was a large disease outbreak on the lake of Taiwan. In 1947 — 1948 the outbreak of the Japanese encephalitis was for the first time revealed on the lake of Guam (zap. part of the Pacific Ocean). According to Hammon (W. Hammon), etc., such flashes on the small isolated Pacific islands arise owing to a drift of a virus patients or mosquitoes from airplanes and sea vessels. In the USSR the natural centers of the Japanese encephalitis are found in Primorsky Krai, however cases of the person in these centers for many years are not observed.

Etiology and epidemiology. The causative agent of the Japanese encephalitis — the virus relating to this. To Togaviridae, sort Flavivirus. A source of a virus of the Japanese encephalitis consider wild and poultry and pigs. Assume that during the interepidemic period the virus remains in an organism of bats and reptiles, also transovarial transfer of a virus at mosquitoes is possible. The main carrier of a virus of the Japanese encephalitis is the mosquito of Culex tritaeniorhynchus; as additional carriers in various geographical areas serve S.'s mosquitoes of annulus (island of Taiwan), S. of gelidus fuscocepha-lus (Malaysia, Thailand), S. vishnui (India). The main line of outbreaks of the Japanese encephalitis is their confinedness by an aestivo-autumnal season.

The pathogeny and pathological anatomy of the Japanese encephalitis are connected with hematogenous distribution of the activator getting after a sting of a mosquito directly to blood. The Neyrotropnost of the activator defines preferential defeat of a nervous system. An essential role in development of a disease is played by secondary immunopathological disturbances.

In a basis morfol. changes at the Japanese encephalitis defeat of vessels of c lies. N of page and other bodies and fabrics. Inflammatory process has diffusion character: the brain and its covers, vegetative nodes, and also heart, lungs, kidneys, a liver and other bodies are surprised. Yellowness and pe-tekhialny rash on skin, multiple hemorrhages in mucous and serous membranes are noted (the epicardium is more often, mucous membranes went. - kish. path), sharp plethora and dystrophic changes of parenchymatous bodies. Meninx is hyperemic and edematous, in them there are hemorrhages. Vessels of a brain are sharply expanded, visible multiple punctulate and more massive hemorrhages, to-rye a thicket are located in the field of basal kernels. Besides, the centers of a necrosis sometimes come to light. The similar, but less expressed changes are observed in a spinal cord. With the help gistol. researches find circulator frustration and inflammatory changes. In bark of a great brain proliferation of an endothelium of vessels, small hemorrhages, perivascular infiltration are noted. The chromatolysis of nervous cells, their destruction is expressed, sites of loss of large cells of bark of a great brain meet. Preferential the II—III and VI layers of bark of a great brain are surprised. Changes are most expressed in frontal lobes.

Immunity. At the persons who had the Japanese encephalitis durable immunity is developed.

Clinical picture. The incubation interval usually

8 — 14 days, but can proceed

from 4 to 21 days. The prodromal stage happens seldom. The disease begins suddenly with rise in temperature to 39 ° above, the general state sharply worsens, it is frequent to extremely heavy. Gradual decrease in the ABP is noted, at nek-ry patients his increase is observed. Sharply breath becomes frequent. Emergence of an oglushennost, confusion of consciousness, excitement, hallucinations is characteristic, the loss of consciousness is quite often observed. Sometimes in several hours after an onset of the illness of the patient perishes. Only in a small number of cases the disease proceeds rather easily.

At most of patients the state happens very heavy. Signs of defeat of a nervous system come to light in the first days or hours of a disease. In addition to disorders of consciousness, the accruing headache, nausea, vomiting is noted, symptoms of defeat of a meninx — muscle tension of a nape, a Kernig's sign appear (see Meningitis). At nek-ry patients these manifestations are the only sign of defeat of a nervous system. In more mild cases indifference, passivity, an echolalia, disturbance of orientation in the place and time, sometimes nonsense is observed. The nature of mental disorders continuously changes. At an aggravation of symptoms of the patient quickly fells into a coma (see), and at improvement symptoms slowly regress. The depression or euphoria, sometimes a catatonic syndrome is quite often noted (see), the delirious syndrome is more rare (see). Myoclonic, fibrillar and fascicular twitchings of separate groups of muscles and extremities, the rough spasmodic tremor amplifying at the movement are characteristic. Signs of defeat of basal kernels — ate-toidny and choreiform hyperkinesias can be observed (see). The local or generalized epileptiform attacks sometimes passing into the epileptic status are frequent (see Epilepsy). Generalized muscular hypertensia is characteristic, increase in tendon jerks is preferential in sgibatel of hands and razgibatel of legs (oppression is more rare). Disorders of sensitivity, as a rule, are not observed, or they have tranzitorny character. In most cases the feverish period would last — 10 days, sometimes longer. There are also short feverish periods, up to 2 — 4 days. Character of a temperature curve is changeable. Most often temperature decreases gradually. Are characteristic tachycardia, bradycardia, change of tones and borders of heart, small increase in a liver is more rare, spleens are more rare, changes in urine, a hamaturia can be observed.

Development of the complications of toksiko-allergic character in connection with an endogenous infection (myocarditis, nephrite, pneumonia, etc.) considerably burdening disease and worsening the forecast is possible.

The diagnosis is made on the basis of data epidemiol. the anamnesis (a season of a disease, visit of places, endemic on the Japanese encephalitis), a clinical picture and results a lab. researches.

In cerebrospinal liquid early emergence of a lymphocytic pleocytosis is characteristic, is more often within 300 — 400 cells in 1 mkl, protein content usually does not exceed 1,2 — 1,5 g! the l, a sugar content is normal. Normalization of cellular composition of cerebrospinal liquid can drag on up to 6 — 7 months. In blood increase in hemoglobin and quantity of erythrocytes is observed. The leukocytosis reaches usually 10 000 — 16 000 in 1 mkl with shift of a formula to the left. Normalization of blood happens slowly, the leukocytosis remains is long. Quite often the quantity of monocytes increases (to 40 — 24%).

Lab. diagnostic methods of the Japanese encephalitis include allocation of a virus from the patient or detection of a viral antigen and identification of immunological reaction of an organism to a viral infection (see. Virologic researches, Hemagglutination). Material for virusol. researches serve the blood and cerebrospinal liquid taken at the beginning of a disease. Allocation of a virus is carried out on newborn white mice by intracerebral and intraperitoneal infection or on culture of cells — the intertwined cells of a kidney of an embryo of a pig, HeLa, VNK-21, etc. (see Cultures of cells and fabrics). Apply diagnostic type-specific immune serums to identification of the allocated virus. For detection of a viral antigen use reaction of an immunofluorescence (see) and immunoenzymatic reactions (see. Serological researches).

At a serological research a diagnostic character is increase of an antiserum capacity in the course of a disease and reconvalescence. For the purpose of detection of antibodies investigate pair serums — the earliest sample taken at height of feverish reaction and the replicate sample taken in

2 — 3 weeks from the beginning of a disease. For identification of antibodies it is possible to use neutralization tests of a virus, braking of hemagglutination, fixation of the complement, an immunofluorescence, radial hemolysis, and also immunosorbentny reactions (an enzyme immunoassay and radio immunoassay). More often than others carry out hemagglutination-inhibition reaction as the simplest and rather reliable method of a serological research. Recently immunosorbentny methods gain ground (especially immunoenzymatic) that is explained by their high sensitivity and specificity (see. Serological researches).

The Japanese encephalitis should be differentiated with a tick-borne encephalitis (see a tick-borne Encephalitis), with serous meningitis (see Meningitis) and with a hemorrhagic nephrosonephritis (see). A tick-borne encephalitis differs in spring and summer seasonality and existence of stings of mites for 1 — 3 week to a course of a disease. Seasonality, existence of stings of mosquitoes, the beginning their less acute, symptoms of encephalitis are not characteristic of acute serous meningitis of various etiology if they join, then later they and quickly disappear. Besides, others are important a wedge, displays of a disease, napr, simultaneous defeat of parotid glands at epidemic parotitis; the gradual beginning at a tubercular encephalomeningitis with accession focal nevrol. symptoms from the 2nd week of a disease. At a hemorrhagic nephrosonephritis signs of damage of kidneys dominate (pains and sharp morbidity in lumbar area, a massive proteinuria, an azotemia, an oliguria). The final diagnosis can be established only after obtaining results of virologic and serological researches.

Treatment presents considerable difficulties. Etiotropic treatment is absent therefore crucial importance is gained by methods of pathogenetic therapy. Rest and the round-the-clock observation in connection with a possibility of emergence of acute mental disorders are necessary. Carry out disintoxication and dehydrational (lasixum, furosemide, Diacarbum, a mannitol, etc.) therapy. Use of glucocorticoids (e.g., Prednisolonum is appointed orally to 1,5 mg to 1 kg of weight a day), salts of potassium, cardiovascular and other means, sposobstvushchy is shown to normalization of a homeostasis. At defeat of the vital centers of a brain trunk carry out resuscitation actions.

P r about of N about z. The Japanese encephalitis is characterized by the high lethality reaching during separate flashes 20 — 70%, and sometimes and 80%, to a thicket death is observed at elderly people and women. At survivors in connection with severe defeat of a nervous system the resistant residual phenomena — paralyzes, disturbances of the speech, amnesia, hyperkinesias, a hearing disorder, a psychoorganic syndrome are quite often noted (see) various degree of manifestation.

Prevention of the Japanese encephalitis is based on use of specific and nespetsifiches-sky means. The vaccine prepared from the virus inactivated by formalin to-ruyu belongs to specific means apply to prevention of a disease of residents of endemic areas.

Nonspecific prevention includes a package of measures of protection against attack of mosquitoes. Individual protection is provided by use of repellents (see) and special clothes — Zhukova's suit (see a tick-borne Encephalitis), protecting screens, and also mesh bed curtains, to-rymi equip berths. Destruction of mosquitoes is carried out by means of insecticides — process places of their breeding, destroyed mosquitoes on halting days in inhabited and non-residential premises by processing by insecticides of walls and a ceiling of rooms.

Other forms of mosquito encephalitis are had in the majority same epidemiol. features, as well as Japanese encephalitis. Their area is rather wide, however many of them meet only in the countries of the western hemisphere.

The Venezuelan, east and western horse encephalomyelitis is widespread in North, Central and South America (see Encephalomyelitis horse).

Encephalitis of Evergleyds in the form of isolated cases is registered in the south of the USA. The infestant is for the first time allocated by R. W. Chamberlain with sotr. (1964) from the mosquitoes of the sort Culex collected in the neighborhood of Evergleyds.

The Western Neil's encephalitis (the Western Neil's fever) meets in Africa, Asia and Europe (see. Tropical mosquito viral fevers).

Encephalitis Ilheus allocated with Lemmert and Hughes (H. W. Laem-mert, T. R. of Hughes, 1947), usually proceeds as a slight feverish disease; the phenomena actually of encephalitis meet less often. The activator is the virus of the same name. The natural natural center of an infection for the first time was found close Ilheus on east Atlantic coast of Brazil. The natural centers of spread of a virus are also in Guatemala, Honduras, Panama, on the lake of Trinidad, in Colombia and Argentina.

Encephalitis Kunying was observed in cases of laboratory infection with the virus allocated to R. L. Doherty with sotr. (1963) from mosquitoes of Culex annulirostris which are brought together near the settlement of Kunying (a coastal zone of the Gulf Gulf of Carpentaria, Queensland, Australia). The virus is found also on the lake of Kalimantan (in Malaysia), however the cases connected with this virus near Malaysia are not revealed.

Encephalitis of the valley of Murray (synonym: the Australian encephalitis, the Australian H-disease) is widespread in a southeast part of Australia in the areas located in the valley of the Murray River. Further the diseases caused by a virus of the valley of Murray were registered in New Guinea. The virus is allocated by Klilend (J. Century of Cleland) with sotr. in 1917 — 1918.

Encephalitis St. Louis was originally found in the USA in 1932 — 1933 in the cities of Paris (State of Illinois) and St. Louis (State of Missouri). During the arisen flashes Makkenfass and Webster (R. Mies-kenfuss, L. T. Webster) allocated the virus which is an infestant and established a role of mosquitoes of the sort Culex in transfer to his person. Further separate cases and the outbreaks of encephalitis St. Louis were registered in many regions of the USA. Natural focuses of the disease are also in Pto anama, Brazil, on the lake of Trinidad and on the lake of Jamaica.

The Californian encephalitis (encephalomeningitis) is observed in the form of separate cases against the background of more numerous slight feverish diseases caused by the same virus allocated with Ham-monom with sotr. in 1952. Diseases are revealed in the forest regions of the USA and Canada.

Encephalitis La Crosse is registered in the USA in the areas located to the East from the Mississippi River and the southeast regions of Canada; tens of cases of a disease are annually observed. The virus is allocated by Thomson with sotr. in 1965.

Tenso's encephalitis — a rare form of mosquito viral encephalitis. The natural natural center of an infection is for the first time found in the USA near river of Tenso. The virus is allocated by Chamberlain with sotr. in 1969.

Rosio's encephalitis also, apparently, belongs to group E. to. The causative agent of this encephalitis belongs to flavivirusa. Transfer of activators mosquitoes is not proved (an estimated carrier of a virus — a mosquito of Psorophora ferox) therefore in group E. to. this disease is included conditionally. The diseases caused by Rosio's virus arise in the form of flashes, are characterized by fever, displays of encephalitis and in some cases come to an end letalno. To a crust, time the disease is revealed only in Brazil.

Viruses, defiant listed E. to., belong to extensive ecological group of an arbovirus (see), and on modern classification — to two virus families — Togaviridae (see Togaviru-sa) and Bunyaviridae (see Bunjyaviru-sa, t. 25, additional materials). In this. Togaviridae activators E. to. enter two sorts — Alpha virus (includes the viruses which are earlier described as an arbovirus of group A) and Flavi-virus (includes the viruses described earlier as an arbovirus of group B; there are reasoned recommendations to consider flavivirusa as the separate Flaviviridae family). More than 20 viruses, including causative agents of encephalomyelitis of horses (see Encephalomyelitis horse) and encephalitis of Evergleyds belong to the sort Alphavirus. 6 activators E belong to the sort Fla vivirus including more than 50 viruses. to. — viruses Ilheus, Kunying, encephalitis of the valley of Murray, the Western Neil's encephalitis, or the Western Neil's fever (see. Tropical mosquito viral fevers), encephalitis St. Louis and Japanese encephalitis. In this. Bunyaviridae activators E. to. enter the sort Bunyavirus including 16 antigenic groups. To the California group of this sort viruses of the Californian encephalitis and La Crosse, and concern to Bunyamver's group — Tenso's virus.

Viruses — activators E. to. exist in the natural centers that, apparently, is caused by constant consecutive transfer by its mosquitoes a vertebrate animal, to-rye, in turn, in the period of a virusemia are a source of infection with a virus of mosquitoes. In maintenance of existence of viruses E. to. birds and rodents probably take part in the natural centers. Carriers of viruses of these forms E. to. mosquitoes are; assume transovarial transfer of viruses mosquitoes, however so far it is found only in mosquitoes of Aedes triseriatus — carriers of a virus La Crosse. Mosquitoes carriers of viruses of these forms E. to. belong to the sorts Aedes, Anopheles, Culex and a nek-eye to others. The transmissible nature of diseases causes their certain seasonality matching the period of a krovososaniye of mosquitoes. In wet tropical districts cases E. to. can arise almost all the year round.

At encephalitis of the valley of Murray carriers of a virus are mosquitoes of Culex annulirostris, S. of pipiens and S. of nigripalpus; at encephalitis St. Louis — S.'s mosquitoes of tarsalis (at approach of the centers to the cities S. by pipiens and S. quinquefasciatus are involved in transfer of a virus). The virus of encephalitis La Crosse is carried by mosquitoes of Aedes triseriatus. S.'s mosquitoes of nigripalpus, Aedes tae-niorhynchus and Anopheles cruciatus take part in transfer of a virus of Evergleyds. At the Californian encephalitis mosquitoes of Aedes vexans, A. nigromacu-lus, A. dorsalis Psorophora signi-pennis, Culiseta inornata and nek-ry other species of mosquitoes can be carriers of a virus, at to-rykh natural infectiousness is established by a virus. Tenso's virus is allocated from mosquitoes of Anopheles crucians, Psorophora confinnis and nek-ry other types of the sorts Anopheles, Mansonia, Aedes u Culex.

The listed forms E. to. have the common pathogenetic features with the Japanese encephalitis, but differ in smaller expressiveness of pathomorphologic disturbances: much less often necrotic changes of brain fabric come to light and there are no sites of perivascular infiltration, damage of backs -

a leg of a brain are noted only at extreme weight of process.

Immunity at E. to. various etiology rather resistant, however recurrent diseases can be observed.

An incubation interval at the listed forms E. to. has approximately the same duration, as well as at the Japanese encephalitis. In most cases not so sharp beginning, as is peculiar to them at the Japanese encephalitis, the smaller frequency and expressiveness nevrol. disturbances.

Diagnosis is same, as at the Japanese encephalitis.

There are no etiotropic methods of treatment, pathogenetic therapy makes a basis of treatment and does not differ from that at the Japanese encephalitis. A lethality at E. to. is much lower than various etiology, than at the Japanese encephalitis.

For prevention E. to. use specific and nonspecific means. The virus vaccines applied at horse encephalomyelitis belong to specific means (see Encephalomyelitis horse). Unlike the Japanese encephalitis against others E. to. specific virus vaccines are not developed. When fact of infection of the person with a virus E. to. it is known or is supposed, recommend as means of passive prevention administration of immune gamma-globulin — hetero logical (horse, goat) either homologous (human) or administration of the corresponding immune serum. Nonspecific means same, as at the Japanese encephalitis (see above). Bibliography: r and shch e N to about in N. I. Mosquito (Japanese) encephalitis, M., 1947, bibliogr.; D zhavets E., Melnik D. JI. and E y d e l e r E. A. The guide to medical microbiology, the lane with English, t. 3, page 125, M., 1982; The Multivolume guide to neurology, under the editorship of S. N. Davidenkov, t. 3, book 1, page 266, M., 1962; The General and private virology, under the editorship of V. M. Zhdanov and S. Ya. Guy-damovich, t. 2, page 49, M., 1982; Tropical diseases, under the editorship of E. P. Shuvalova, page 60, etc., D., 1979; Diagnostic procedures for viral., rickettsial and chlamydial infections, ed. by E. H. Lenette a. N. J. Schmidt, Washington, 1979; International catalog of arboviruses including certain other viruses of vertebrates, suppl., ed. by N. Karabatsos, Lawrence, 1978; To a n e k o R. u. A o k i Y. Ueber die Encephalitis epidemica in Japan, Ergebn. inn. Med. Kinderheilk., Bd 34, S. 342, 1928; Principles and practice of infections diseases, ed. by G. L. Mandell a. o., v. 2, N. Y., 1979.

K. G. Umansky; S.G. Drozdov, B. F. Semenov (etiol., epid., laboratory diagnosis, prevention).

Яндекс.Метрика