The Japanese encephalitis Is considered a serious viral infection, produced by the bite of a carrier mosquito and that mainly courses with inflammation of the cerebral tissue. The first case of this type of encephalitis was documented in the year 1871 in Japan, and since then cases have not stopped appearing.
Encephalitis is a medical condition in which an inflammation of the brain occurs in response to the entry of pathogens such as viruses, parasites and bacteria. It can affect both animals and humans.
Japanese encephalitis, from the Greek ἐγκέφαλος ("brain") and suffix -itis (inflammation), receives the oriental adjective because the first case of this disease was documented in Japan.
People with immunosuppressive diseases, such as HIV, are more susceptible to encephalitis. Parasitic infections such as Cysticercus wave Toxoplasmosis , Can occur with the development of encephalitis.
There are a lot of common viruses that can produce inflammation of the brain tissue, such as: herpes simplex virus, measles, mumps, rubella, or chickenpox. However, it can also occur in response to more complex viral infections such as adenovirus or Japanese encephalitis, a disease we will focus on today.
The World Health Organization (WHO) indicates that this disease appears in severe outbreaks for periods of 2 to 15 years, sometimes even occurring in epidemics.
It is estimated that at least 68,000 cases of Japanese encephalitis occur every year, of which approximately 30% to 50% will suffer permanent psychological and neurological sequelae, and up to 20% will die during the course of the disease.
It is the leading cause of encephalitis in Asian regions such as Sri Lanka, Indonesia, Nepal or the Philippines, and it is very rare to find cases of Japanese encephalitis in tourists, visitors or countries in other regions.
Although in most cases the virus responsible for this disease only produces mild symptoms, infection caused by Japanese encephalitis can produce massive and widespread inflammation in brain , Which can lead to permanent injuries to this organ, leading in the most serious cases to cause death.
At present, there are safe and fairly effective vaccines to prevent the onset of this disease. However, there is no cure for Japanese encephalitis, so treatment is usually focused on relieving clinical symptoms and eliminating infection.
Since encephalitis may appear as a response to numerous organic causes, the diagnosis of Japanese encephalitis requires extensive analysis. Sometimes, the blood test is not enough to confirm the diagnosis of this disease so it is usually confirmed with an analysis of the cerebrospinal fluid.
Causes of Japanese Encephalitis
Japanese encephalitis is transmitted through the bite of a mosquito carrying the disease, and it is not possible to spread from person to person. The mosquito becomes a carrier of the disease by sucking the blood of an infected animal or human.
Birds and pigs are usually the most frequent hosts of this infection, so mosquitoes that transmit Japanese encephalitis are often found in agricultural regions and city suburbs. As birds and pigs are the favorite reservoir of the disease, it is extremely difficult to eradicate this infection.
The virus carried by these mosquitoes belongs to the family of Flaviviridae (So are yellow fever or dengue), and it is found in the saliva of the mosquito itself. When the bite of the carrier insect occurs, whether in animals or humans, the virus enters the bloodstream first affecting the organs and later to the central nervous system. The incubation period of the disease in the organism is from 4 to 16 days.
Mosquitoes that transmit this infection prefer warm and humid environments, so they tend to sting their victims at night. In fact, most cases of Japanese encephalitis occur in the summer months, where rainfall is more frequent and the climate is conducive to its reproduction.
symptom
Most people who are infected with the Japanese encephalitis virus will experience the disease with little or no symptoms. It is estimated that less than 1% of cases will show severe signs of the disease. Children and the elderly are the most vulnerable to this infection, accounting for 75% of all cases in children under 15 years.
In mild cases, the clinical manifestations most observed in these patients are dizziness, nausea, vomiting and headache Without neurological signs, so it is common to confuse the symptoms with those of a common cold or flu.
In the most severe cases, when inflammation of brain tissue occurs, symptoms progress rapidly. These patients present changes at neurological and psychological levels such as disorientation, muscular rigidity in the neck region, high fevers and alterations of consciousness.
If the fevers are very high they give rise to convulsions and can produce, from coma states until the death of the patient. Recent studies have shown that infection with this virus in a pregnant woman can cause permanent damage to the fetus as well.
According to the WHO, between 30% and 50% of those infected with Japanese encephalitis will suffer permanent psychological and neurological sequelae. These deficits may include problems with attention, memory, or Other basic cognitive processes ; Changes in personality, muscle tremors, and even limb paralysis. In these patients, the recovery period may be greater than one year.
As for the mortality of people suffering from Japanese encephalitis, up to 20% of those infected will die during the course of the disease.
Treatment
At present there is no cure for the Japanese encephalitis virus, so the intervention in the health of these patients focuses mainly on the control of fever, pain and neurological symptoms.
Although the majority of patients infected with the disease present no symptoms, when the diagnosis is confirmed in these patients, hospitalization is usually necessary to observe and control the course of the disease.
Prevention with vaccination
The greatest sanitary intervention we can take to control the occurrence of Japanese encephalitis is prevention, either through protection against mosquito bites or through vaccination.
There is a vaccine specially developed to combat the Japanese encephalitis virus. This vaccine is indicated for all those people who intend to stay more than 3 or 4 weeks in one of the countries or regions where this infection is more frequent. Since children are the largest risk group in this pathology, the vaccine is indicated for application from two months of age.
The vaccination process against Japanese encephalitis consists of the administration of two injections, one at the beginning of the treatment and the other at 28 days, being necessary that the latter is received at least one week before the beginning of the trip.
Vaccination under these guidelines provides protection against infection for a whole year. In cases where the person needs more prolonged protection, a third dose of the vaccine may be given to provide up to three years of protection against the virus (although the effects of this third dose of booster in children are not known).
Cases in which vaccines are recommended
The following are all cases where the administration of the vaccine is highly recommended:
- Persons planning a stay of more than one month in areas where the infection is most present: Bangladesh, Brunei, Cambodia, China, Korea, India, Indonesia, Japan, Malaysia, Laos, Myanmar, Nepal, Papua New Guinea, Singapore, Sri Lanka, Thailand, Taiwan and Vietnam.
- People planning a stay less than a month, but in rural or agricultural areas of regions where this infection occurs.
- People traveling to regions where there is an active outbreak of the disease.
- People who do not have a correct travel plan.
- People who work in laboratories or health centers and are at risk of exposure to the virus.
Just as there are cases where vaccination is almost mandatory, there are others where vaccination is not recommended at all. For example, in people who have manifested an allergic reaction to other vaccines or in pregnant women.
Vaccination with Japanese encephalitis produces mild side effects in most cases. Thus, 40% of those vaccinated claim to have had one or more of the following side effects: muscle pain, redness and inflammation of the puncture site and headache.
In more severe cases, the side effects of this vaccine can produce hives, inflammation of the internal organs and difficulties to breathe. In any of these situations, the person vaccinated should see their doctor to control the symptoms.
Despite all of the above, the vaccine is not 100% effective, so in addition to vaccination, the use of protective measures against mosquito bites is strongly recommended.
Protection measures against mosquito bites
Mosquitoes feed on the blood of other animals, including humans, and are attracted to body-scented secretions such as sweat or carbon dioxide that is expelled by breathing.
These insects reproduce in stagnant water, so it is very common to appear in areas with rivers, ponds, pools and pools. However, mosquitoes can also be reproduced in tanks or containers for the water store.
To prevent mosquito bites, it is best to stay in conditioned rooms and use mosquito nets or anti-mosquito nets on doors and windows. It is also important to use insecticides when it is impossible to keep the room completely closed.
During outdoor stay it is even more important to prevent bites. The best way to get it is by wearing proper footwear and clothing. Shoes or boots should be closed. The garments to be possible of light colors and the shirts or vests with long sleeve.
It is important to remember that mosquito bites can pierce thin, tight clothing, including jeans. However, if areas of the skin are exposed or there are activities that produce sweating, such as cycling, hiking or other sporting activities, it is advisable to use repellents.
The most suitable repellents to prevent the sting of this type of mosquitoes are those whose active principle is DEET ( N-diethyl-toluamide ). The DEET acts by obstructing the sensors that attract the mosquito to the body odor, confusing it so that it does not pose on the skin and does not end up producing pitting.
This compound has been used in the last 40 years by millions of people around the world to combat not only mosquito bites but also spiders, fleas, flies, etc. DEET repellents are available in many formulations like creams, lotions or aerosols.
Being a very potent chemical compound, it is necessary to always follow the recommendations of our doctor and the manufacturer of the product. However, there are certain precautions that must always be considered when using these repellents.
Tips for using repellents
Below are the 10 most important tips to keep in mind when using these products.
- Read and follow label directions. Avoid overuse and multiple applications.
- Products containing 25% to 35% DEET will provide adequate protection for adults. Under the same conditions, a concentration of 10% to 15% will be sufficient for children.
- To prevent a possible allergic reaction to the product before applying it throughout the body, it is necessary to apply it on a small area of the skin and observe that no allergic reaction occurs.
- Use only enough repellent to cover exposed skin and / or clothing.
- Once out of danger of stings, wash treated skin and all clothing before reuse.
- Do not apply directly to the face. Spread the repellent product on your hands and then apply it to your face. Avoid sensitive areas such as eyes, mouth, or nasal membranes.
- Do not apply to any injuries, burns or irritated skin.
- Do not use under clothing.
- Avoid spraying on plastics, leather, glass or other fibers. DEET can permanently damage these materials.
- Never use a product with DEET in enclosed areas.
- Products with DEET are resistant and repel mosquitoes for a few hours. It is therefore important never to apply more product than necessary.
Vitamins to prevent stings
In addition to the repellents we have described, it is necessary to comment that some studies indicate the usefulness of daily Vitamin B1 (Also known as tyrosine), to repel mosquito bites. They report that ingestion must be done for at least two weeks before the trip and during the entire stay in the country.
Apparently, the secretion of this vitamin by the skin gives off an odor that is imperceptible to the human, but unpleasant to the mosquito, causing it does not produce stings.
However, there is no scientific evidence to support its use, so preventive care in the environment and the use of repellents are still the first option to prevent these stings; And consequently Japanese encephalitis.