After the typhoon and rainstorm, beware of mosquitoes and Japanese encephalitis invasion

This is the 4492nd article of Da Yi Xiao Hu

On July 28, the super typhoon "Dusurui" landed on the southeast coast of my country. Under its influence, Fujian, Zhejiang, Beijing and other provinces and cities successively ushered in strong winds and heavy rainfall, and many places were affected. After the typhoon, public areas such as roads, communities, green spaces, and many outdoor natural containers such as depressions, tree holes, fallen leaves, artificial containers, waste bottles and tires all had serious water accumulation, becoming natural breeding grounds for mosquitoes, which easily caused the "explosive" growth of mosquitoes. Mosquitoes have a strong reproductive capacity. A female mosquito alone can lay more than a thousand eggs. Female mosquitoes lay eggs in stagnant water and can emerge in about a week. The harm of mosquitoes is not only their bites, but also the key is that they can spread a serious disease through bites - epidemic encephalitis B.

Epidemic Japanese encephalitis (JE) , also known as Japanese encephalitis, is an acute infectious disease caused by the JE virus transmitted through mosquito bites. In China, the epidemic season of JE is mainly concentrated in summer and autumn every year. In subtropical and temperate regions, JE is mostly prevalent from July to October. China has classified JE as a Class B infectious disease.

The general population is susceptible to the Japanese encephalitis virus. Since the blood-brain barrier function of children is weaker than that of adults, the incidence of Japanese encephalitis is mainly in children under 10 years old. Japanese encephalitis has an acute onset and progresses rapidly. In the early stage, the main symptoms are fever, mental depression, drowsiness, lack of appetite, headache, etc. As the disease progresses, high fever, impaired consciousness, convulsions and other manifestations may appear. In severe cases, respiratory failure and even death may occur. The mortality rate of severe Japanese encephalitis is high, and 30% to 50% of severe cases have serious sequelae, such as mental retardation, aphasia, limb paralysis, impaired consciousness, mental disorders and dementia. In recent years, due to the widespread vaccination of children and adolescents with Japanese encephalitis vaccines, the incidence rate has dropped significantly, and the trend of the disease has gradually shifted to older age groups and adults.

Japanese encephalitis is a mosquito-borne infectious disease and a natural zoonotic disease. Many livestock (pigs, sheep, cattle, horses, etc.) and poultry (chickens, ducks, geese, etc.) can become important sources of infection for Japanese encephalitis. Among them, pigs have the highest natural virus-carrying rate and are the main source of infection. In addition, the Japanese encephalitis virus will not cause human-to-human transmission. The main route of transmission is through mosquito bites carrying the virus, thus forming a transmission chain of pigs (source of infection) → mosquito bites (transmission route) → humans (susceptible population).

So far, no specific drug has been invented to treat Japanese encephalitis. The prevention of Japanese encephalitis should take comprehensive measures, mainly mosquito prevention, mosquito killing and vaccination. In addition to controlling the source of infection and cutting off the transmission route, vaccination should also be used to protect susceptible people. Vaccination is the most economical and effective preventive measure to prevent Japanese encephalitis.

At present, there are two types of Japanese encephalitis vaccines used in my country, namely live attenuated Japanese encephalitis vaccine and inactivated Japanese encephalitis vaccine:

Live attenuated Japanese encephalitis vaccine

A total of 2 doses are given, 1 dose each at 8 months and 2 years of age;

Japanese encephalitis inactivated vaccine

A total of 4 doses are given, 2 doses at 8 months of age (7-10 days apart), and 1 dose each at 2 and 6 years of age.

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Contraindications of Japanese encephalitis vaccine

People who are allergic to any ingredient (including excipients) contained in the vaccine; people with acute diseases, serious chronic diseases, acute attacks of chronic diseases or fever; patients with uncontrolled epilepsy, encephalopathy or other progressive neurological diseases; pregnant women, the above groups are prohibited from using live attenuated Japanese encephalitis vaccines and inactivated vaccines.

Live attenuated Japanese encephalitis vaccine is contraindicated in patients with immunodeficiency, immunosuppression or those receiving immunosuppressive treatment.

In addition, if suspected symptoms such as Japanese encephalitis appear, you should seek medical attention as soon as possible to avoid delaying the treatment.

Appendix: Five tips for clearing stagnant water and mosquito larvae breeding grounds

Turn over : Pour out accumulated water from small containers such as jars, cans, basins, jars, and bottles, and place them with the bottom facing up to keep them dry.

Fill : Use soil and sand to fill various pits, depressions, ditches and other holes that are prone to water accumulation.

Clean : Clear various small containers in the environment, such as beverage bottle caps, garbage bags, etc.

Dredging : dredging open ditches, sewers, ditches, rivers, etc.

Medicine : For stagnant water that cannot be cleared, such as rainwater wells, long-lasting mosquito larvae killers should be used.

Author: Director of Pediatrics, Fujian Provincial Hospital

Chen Lang, Chief Physician and Professor

Illustration: Fujian Provincial Preventive Medicine Association Science Popularization Committee

Chen Wentao, Vice Chairman