First, there was malaria. Then dengue fever came. Zika virus also caused some panics among Filipinos. And now, there’s Japanese encephalitis. All four diseases have one thing in common: they are spread through mosquito bites.
Last year, a 52-year-old man from Bacaca in Davao City was confirmed positive for Japanese encephalitis. Although he survived and discharged from the hospital, he reportedly suffered “from neurologic diseases, including memory lapses.”
“You should not be so complacent that there is just one case,” Dr. Josephine Villafuerte, Davao City Health Officer, was quoted as saying. “We have to take into consideration that we have a lot of mosquito-borne illness…”
Endemic in the Philippines, “Japanese encephalitis is a very serious disease,” to quote the words of Dr. Sally Gatchalian, the president of the Pediatric Infectious Disease Society of the Philippines.
According to the Geneva-based World Health Organization (WHO), three out of 10 patients who exhibit severe symptoms die. Every year, around 68,000 severe cases of Japanese encephalitis are reported every year around the globe. Most of the cases are from Asia.
From January to August this year, about 57 cases have been recorded by the Department of Health (DOH). Five of these cases led to death, including the 20-year-old engineering student from San Fernando, Pampanga who died last August.
There were also reports that two children also died of Japanese encephalitis in Laguna just this month.
“We’ve been having cases of Japanese encephalitis for so long, but more cases came out because we are doing surveillance,” Health Secretary Paulyn Ubial told reporters recently.
Among those that have been monitored for the illness since 2014 are Regions I, III, VII, XI and the Cordillera Administration Region.
The viral brain infection is caused by Japanese encephalitis virus, which is related to dengue, yellow fever and West Nile viruses. It is transmitted to humans through the bite of an infected Culex species mosquitoes, particularly Culex tritaeniorhynchus.
According to an article published by Medical News Today, wild birds are the natural host of the virus while the mosquitoes are the vectors. “A vector does not cause a disease but passes it on,” it explains.
Encephalitis means “inflammation of the brain.” The first case of Japanese encephalitis viral disease was first reported in Japan in 1871. This must be the reason why it is called as such. However, the disease is endemic in 24 countries in Southeast Asia and Western Pacific regions.
“Not only humans are affected by the virus,” wrote Sy Kraft, author of the Medical News Today feature. “Mosquitoes can also infect horses and pigs, leading to encephalitis in horses and abortion in pigs.”
When mosquitoes infect an animal, the animal can become a carrier of the virus. When other mosquitoes feed on these newly infected animals, they take up the virus and can go on to infect the other animals or humans.
The virus cannot be transmitted from one person to another. As such, you cannot get the virus from touching or kissing a person who has the disease, or from a health care worker who has treated someone with the disease.
Oftentimes, the disease likely affects children. Adults in areas where it is endemic generally become immune as they get older. “But individuals of any age may be affected,” the United Nations health agency points out.
Japanese encephalitis is more common in rural areas where there are pig farms and rice fields. As such, “people in rural areas are at highest risk,” Kraft wrote. “Japanese encephalitis does not usually happen around towns and cities.”
Most people infected with Japanese encephalitis virus have either no symptoms, or mild, short-lived symptoms, which are often mistaken for flu. “Once a person has the disease, treatment can only relieve the symptoms,” Kraft wrote. “Antibiotics are not effective against viruses, and no effective anti-viral drugs have been discovered.”
The health website of the United Kingdom notes that “around one in every 250 people who become infected develop more severe symptoms, as the infection spreads to the brain.”
This usually happens five to 15 days after infection. The symptoms include: high temperature (fever), seizures (fits), stiff neck, confusion, inability to speak, uncontrollable shaking of body parts (tremor), and muscle weakness or paralysis.
The chance of survival varies, but children are most at risk. “Up to one in every three people who develop the more serious symptoms will die as a result of the infection,” the website said.
The symptoms of those who survive tend to improve slowly. “However, it can take several months to make a full recovery and up to half of those who do survive are left with permanent brain damage,” said the website. “This can lead to long-term problems such as tremors and muscle twitches, personality changes, muscle weakness, learning difficulties and paralysis in one or more limbs.”
As stated earlier, there is no antiviral treatment for patients with Japanese encephalitis. However, there is safe and effective vaccines to prevent the disease. In fact, WHO recommends having strong Japanese encephalitis prevention and control activities, including Japanese encephalitis immunization “in all regions where the disease is a recognized public health priority, along with strengthening surveillance and reporting mechanisms.”
The health department is thinking of adding the Japanese encephalitis vaccine to the list of publicly mandated and available vaccines next year. In an announcement, Dr. Ubial said she planned to include it in the country’s national immunization program in 2018.
A news report from ABS-CBN quoted Ubial saying that “vaccines for the disease are limited in the country” as they are expensive, ranging from P3,500 to P5,000 each.
The UK website said that the vaccine “gives protection against Japanese encephalitis in more than 9 out of 10 people who receive it.”
The WHO said there are four main types of Japanese encephalitis vaccines currently in use: inactivated mouse bran-derived vaccines, inactivated Vero cell-derived vaccines, live attenuated vaccines, and live recombinant vaccines.
Even if you’ve been vaccinated, you still need to take necessary precautions to reduce your risk of being bitten by an infected mosquito in areas where it is common. The UK website recommends the following:
Sleep in rooms with close-fitting gauze over the windows and doors. If you’re sleeping outside, use mosquito nets that have been impregnated with an insecticide.
Cover up with long-sleeved tops, trousers and socks.
Apply a good-quality insect repellent to exposed areas of skin.
