IIn the summer of 2003, a female child in a certain county of Guangdong Province was reported to suffer from high fever and hyperspasmia. Within 10 days henceforth, 27 cases with the same symptoms were successively reported to the health department of the county. The disease, according to experts’ diagnosis, was Meningococcal Meningitis (Encephalitis B). Within one month, a total of 221 cases of Meningococcal Meningitis had been reported throughout the province, among which patients 18 died.
How is Meningococcal Meningitis transmitted?
Meningococcal Meningitis is an acute central-nervous-system infectious disease which is caused by Japanese Encephalitis Virus (JEV). It is mainly prevails in East Asia and South Asia. China is also an epidemic area for Meningococcal Meningitis, where around 10 thousand Encephalitis B cases are estimated to occur every year.
JEV can infect human beings and various animals, such as pigs, horses, cows, sheep and dogs, among which, the pig is of the highest infection rate, nearly 100%.Besides, the viruses invading the blood of the pigs may stay for the longest time, and of the biggest amount, compared to those invading the other animals. Thus, the pig proves a major infection source of Encephalitis B. When mosquitoes that have bitten infected pigs bite the human beings, it may result in an epidemic situation of human Meningococcal Meningitis. The period between July and September is the peak season of Meningococcal Meningitis in China.
The mosquito is the primary criminal responsible for the communication of JEV. JEV does not communicate through the contact between healthy and infected people. Many types of mosquitoes, including Culex, Aedes and Anopheles, can spread JEV. Human being does not have innate immunity against JEV. However, only a very small proportion of people (less than 0.1%) may exhibit typical symptoms after being infected. Most people can be immunized through light or latent infection, and the immunity of one recovered from the infection is usually very strong and enduring. Hence, infants and children under the age of 10 are more easily infected, representing the most susceptible population, accounting for more than 80% of the infected incidence. When one is bit by virus-carrying mosquitoes, the virus will invade the blood. However, whether or not the person will get Meningococcal Meningitis still depends on 2 factors: a) the amount and virulence of the virus b) the immunity of the invaded body. When the person’s immunity is stronger than the virulence of the virus, JEV will be killed. Otherwise, the person will get Meningococcal Meningitis.
Symptoms and Harms
The incubation period of Meningococcal Meningitis is usually between 10 to 14 days. The whole course of the disease in typical cases can be segmented into 4 phases.
1. Preliminary Stage
Meningococcal Meningitis develops rapidly, and temperature of the infected body can reach above 38℃. Accompanied symptoms include headache, nausea, vomiting, sleepiness, and so on. Respiratory tract symptoms and diarrhea can also be found in the cases of infant patients.
2. Fastigium Stage
Symptoms in this stage include continuous high fever, disorder of consciousness, convulsions or hyperspasmia，and respiratory failure, etc. Patient that cannot recover from this period may not survive. The mortality of meningococcal disease is around 10%.
3. Convalescent Stage
It usually takes 2 weeks for the patient to recover from the disease. For some patients, this period may be longer, about 1 to 3 months. In the worst case, it will take 6 months for the recovery of serious patients.
4. Sequela Stage
Most patients will recover from Meningococcal Meningitis. A few serious patients may suffer from some nervous system or mental sequelae though, such as aphasia, paralysis and mental disorder.
What should be the reaction in face of the above mentioned symptoms?
The symptoms of Meningococcal Meningitis at a preliminary stage are quite similar to influenza. As a result, Meningococcal Meningitis at its preliminary-stage is often misread as heavy flu, thus ignored, which result in a delay of the diagnosis and the treatment. Therefore, once preliminary-stage symptoms, such as fever or headache, arise in the epidemic season of Meningococcal Meningitis, the appropriate person should timely seek treatments from the hospital. Only timely discovery of the disease will ensure a proper treatment and a satisfactory recovery, and thereby lower the mortality, and minimize the incidence of sequelae. In addition, family members should actively cooperate with the doctor in the treatments of Meningococcal Meningitis, which is another very important factor.
How to conduct self-protection?
Presently, there is no outstanding treatment method yet for Meningococcal Meningitis. A ready prevention process is critical for the control of this disease, which consists of two key points.
1. Vaccination
Vaccination is the most effective method for preventing and controlling Meningococcal Meningitis. The period between July and September each year is the peak season of Encephalitis B in China. Encephalitis B vaccination in the country is usually carried out between April to June, 3 months right before the peak season. And Encephalitis B vaccination has already been incorporated into Children Vaccination Scheme. However, some children in rural and impoverished areas fail to get immunized for various reasons. In the summer of 2003, Meningococcal Meningitis broke out in some regions of the Guangdong Province due to the absence of vaccination of the Child in such regions..
2. Mosquito Eradication and Prevention
To carry out patriotic cleaning-up activities and eradiate mosquitoes, can cut off the approaches for the communication of Encephalitis B; Ward against mosquito bites will reduce the chance of infection and confine the epidemic situation.