Animal (monkey) smallpox: causes, symptoms, diagnosis, treatment

Animal pox is a group of zoonotic infectious diseases caused by viruses of the Poxviridae family and characterized by fever and a vesicular-pustular rash. These include monkeypox, cowpox, diseases caused by the vaccine virus and its subspecies, the buffalopox virus, as well as pseudocowpox (paravaccine) and Tanapox. The causative agent of pseudocowpox belongs to the genus Parapoxvinis, Tanapox belongs to the genus Yatapoxvirus, and the others belong to the genus Orthopoxvirus. Monkeypox clinically resembles smallpox and is the most dangerous, since it can be transmitted from person to person, and the causative agent is very close genetically to the smallpox virus. Other poxvirus infections are manifested by single vesicular-pustular elements and regional lymphadenitis.

Monkeypox (Lat. variola vimus) is an acute zoonotic natural focal viral infectious disease common in tropical forests and savannahs of the equatorial zone of Central and West Africa and characterized by intoxication, fever and vesicular-pustular rash.

ICD-10 code

B04. Infections caused by monkeypox virus.

Epidemiology of Monkeypox

The source and reservoir of the pathogen are sick primates of 12 species (cercopithecus, colobus, gibbons, gorillas, chimpanzees, orangutans, etc.) and tropical squirrels. The duration of the virus shedding period is unknown. Humans become infected from sick animals by contact (through the conjunctiva and damaged skin) and airborne or airborne dust (aerosol infection mechanism). The natural susceptibility of humans is unknown. A sick person can be a source of the infectious agent.

The first outbreaks of monkeypox were registered in 1958 at intervals of four months at the State Serum Institute in Copenhagen in Javanese macaques imported from Singapore. Subsequently, outbreaks were noted in 78 laboratories in different countries working with monkeys. At the end of August 1970, in the Equateur Province of the former Republic of Zaire (Democratic Republic of the Congo), the first case of monkeypox was recorded in a 9-month-old boy. In 1970-2003, about 950 cases of monkeypox in humans were registered in the Democratic Republic of the Congo, the Central African Republic, Gabon, Cameroon, Nigeria, Côte d'Ivoire. Liberia. Sierra Leone. In 2003, it was detected in 37 people in the USA. More than 95% of all cases of the disease were detected in the Democratic Republic of the Congo. Over 450 cases of monkeypox in humans were reported in 1996-1997 in two districts of the province of Kasai-Oriental, with 73% of cases being confirmed as human-to-human transmission. The most affected group is children aged 4-10 years. Seasonality is summer.

When monkeys with smallpox or suspected of having the disease are identified, the same anti-epidemic and preventive measures are taken as for smallpox, including vaccination with the smallpox vaccine.

In tropical areas of Central and West Africa where monkeypox is endemic, routine vaccination of the population is recommended.

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What causes monkeypox?

Monkeypox is caused by a virus of the genus Orthopoxvirus of the family Poxvuidae. In terms of morphological and antigenic properties, it is close to the smallpox virus, but differs from it in its main biological properties:

• on the chorion-allantoic membrane of chicken embryos at a temperature of 34.5-35.0 °C the virus multiplies with the formation of small pockmarks with central hemorrhage and single large white pockmarks: the maximum development temperature is 39.0 °C;
• has pronounced hemagglutinating activity;
• does not have a cytopathic effect and does not cause the phenomenon of hemadsorption in the cells of the transplanted line of pig embryo kidneys. Resistance to the effects of environmental factors is the same as that of the smallpox pathogen.

Pathogenesis of monkeypox

The phases of monkeypox pathogenesis are the same as those of smallpox, but with the development of more pronounced inflammatory changes in the lymph nodes.

Symptoms of Monkeypox

The incubation period of monkeypox lasts from 7 to 21 days.

The main feature that distinguishes monkeypox from smallpox is the development of lymphadenitis in 86% of patients. It occurs in the prodromal period simultaneously with the appearance of monkeypox symptoms: fever up to 38.0-39.5 °C, headache, myalgia and arthralgia. Lymphadenitis can be bilateral or unilateral and, depending on the entry point of infection, develops in the submandibular, cervical, axillary or inguinal lymph nodes. With the development of exanthema, generalized lymphadenopathy develops in 64% of patients. With the aerosol mechanism of infection, patients note a sore throat and cough. The periods of rash, suppuration and convalescence are practically no different in clinical manifestations from smallpox, but usually proceed more easily and quickly (in 2-4 weeks). According to Rao's classification, monkeypox in humans occurs in the usual form of the discrete variant in 58% of cases, and in the semi-confluent and confluent forms in 32 and 10% of cases, respectively. The development of smallpox purpura (one case in a child), a discrete variant of varioloid, smallpox without rash, smallpox without fever, and inapparent form is possible.

Complications of monkeypox

Monkeypox is most often complicated by bacterial infections: bronchopneumonia, keratitis, diarrhea, phlegmon, abscesses and others.

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Mortality

The mortality rate for monkeypox is on average 3.3-9.8% (depending on the age of the patients). In the age group over 10 years, no fatal outcomes have been registered.

Diagnosis of monkeypox

The diagnosis of monkeypox is the same as that of smallpox.

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Treatment of monkeypox

Bed rest (lasts until the crusts fall off). Diet - mechanically and chemically gentle (table No. 4). Treatment for monkeypox is the same as for smallpox.

Clinical examination

Not regulated.

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Monkeypox Prognosis

Monkeypox has a different prognosis, which depends on the clinical form and age.