Japanese encephalitis has a high mortality and complication rate of up to 35%. Notably, the disease is often difficult to detect early because its initial symptoms closely resemble those of other infections.
Recently, the Hanoi Department of Health reported a 12-year-old boy from Phuc Tho District as the first case of Japanese encephalitis in the city this year.
On June 16, the boy exhibited symptoms of high fever and headache. The following day, he developed neck stiffness and unsteady walking, prompting his family to take him to the Central Pediatric Hospital.
Examinations and tests, including Mac-Elisa testing of the child’s cerebrospinal fluid, confirmed a positive diagnosis for the Japanese encephalitis virus.
It is noteworthy that the boy had previously received four doses of the Japanese encephalitis vaccine, with the last dose administered on June 15, 2019.
Anyone, regardless of age, who lacks immunity to the Japanese encephalitis virus can contract the disease. The disease primarily affects children under 15 years old, accounting for over 90% of cases, with most being children aged 1 to 5 years. The disease is transmitted by mosquitoes, progresses rapidly, and has a high rate of complications and mortality. It is estimated that about 30% of hospitalized patients die; approximately one-third to one-half of those who survive suffer from severe neurological and psychiatric complications.
Children vaccinated with 3 doses of the Japanese encephalitis vaccine have a protection efficacy of 90-95%.
This virus previously caused 15-20% of cases of encephalitis in children, but the rate has now decreased to 8-10% following the implementation of vaccination in the expanded immunization program. The main symptoms of the disease include high fever accompanied by symptoms related to central nervous system damage, such as headache, nausea, and vomiting. Children may exhibit insomnia, crying, restlessness, or lethargy, convulsions, increased muscle tone, and autonomic nervous system disorders (skin may alternate between red and gray, sweating, rapid pulse).
To prevent the disease, the public should pay attention to environmental hygiene, keeping living areas clean, and ensuring that animal enclosures are maintained to prevent mosquito breeding. It is advisable to use mosquito nets and not to allow children to play near livestock pens, especially during dusk to prevent mosquito bites. Mosquitoes that transmit encephalitis typically bite at night. If there are signs of high fever along with symptoms of central nervous system damage, it is essential to take the child to a medical facility immediately for diagnosis and timely treatment.
The best preventive measure is vaccination, but children must receive the complete dosage. According to Dr. Tran Dac Phu, Director of the Department of Preventive Health, Ministry of Health, typically for other vaccines, one dose is sufficient for some level of protection (even if low); however, the Japanese encephalitis vaccine works differently. If only one dose is administered, it will not provide effective protection. Receiving two doses results in over 80% protection efficacy. Completing three doses achieves a protection efficacy of 90-95% for approximately three years.
Japanese encephalitis is extremely dangerous for children due to the high mortality and complication rates.
The peak of the epidemic occurs in June and July. After October, mosquito density decreases, and the epidemic ends. Therefore, the health sector advises parents to adhere to the vaccination schedule as follows:
For children under 5 years old: Administer 3 basic doses according to the extended vaccination program schedule.
- Dose 1: When the child turns one year old.
- Dose 2: 1 to 2 weeks after the first dose.
- Dose 3: One year after the second dose.
Then, a booster dose should be given every 3-4 years until the child is over 15 years old.
For children over 5 years old who have never been vaccinated, they should also receive the 3 basic doses, with the intervals similar to those mentioned above.
What is Japanese Encephalitis? Japanese Encephalitis is an acute infectious disease transmitted through the blood caused by the Japanese encephalitis virus. In Vietnam, Culex tritaeniorhynchus mosquitoes breed heavily during the summer (especially from March to July) and are highly active at dusk. This mosquito species is prevalent in lowland and midland areas and is the primary vector for transmitting Japanese encephalitis in the country. The disease often causes encephalitis and meningitis in children, with a high mortality and complication rate (25-35%). Japanese encephalitis is often difficult to detect early due to its initial symptoms resembling those of other infections. By the second or third day of illness, symptoms such as sudden high fever, nausea, dry vomiting, headache, sluggish reaction, and lethargy become more pronounced. The disease progresses very rapidly; within 3 days, or even within one day, patients may show signs of convulsions, coma, and may require mechanical ventilation, with death occurring within just 1-2 days. Additionally, the disease can cause long-term neurological complications, resulting in decreased communication ability, reduced or lost work capacity, and becoming a burden for families and society. |
