Infectious diseases transmitted by other mosquitoes

Japanese encephalitis

Japanese encephalitis is caused by the Japanese encephalitis virus. This disease is a major health problem in South and South-East Asia. It has also been observed in the far north-east of Australia. The virus is present in pigs and aquatic birds, and it is from these reservoirs that mosquitoes of the genus Culex (same family as the domestic mosquito) can transmit it to humans.  Humans are so-called "epidemiological dead-ends" for the virus, as they no longer contribute to the transmission of the disease. This is because the virus does not develop in these hosts, leaving insufficient quantities of the virus in the blood to infect a mosquito when bitten.  

What are the symptoms and complications?

Most infections go unnoticed or have mild symptoms. After an Incubation period Time between infection and appearance of symptoms. of 5 to 15 days, symptoms such as fever, muscle aches and headaches appear. In children, abdominal pain and vomiting may also occur. In these mild forms, recovery occurs after a few days. 

In a minority (around one in 200 to 250 people), serious symptoms develop, such as encephalitis (inflammation of the brain) or meningitis (inflammation of the meninges, i.e. the covering of the spinal cord and brain). This is more common in young children and the elderly. One in three patients suffering from a serious illness dies as a result. If the patient survives, they may suffer permanent neurological or psychiatric after-effects. Adults living in areas where Japanese encephalitis is Endemic Persistent circulation of a disease or Pathogen Micro-organism capable of causing disease. in a population or geographical area. generally develop some form of immunity.

How is Japanese encephalitis diagnosed?

If the doctor suspects Japanese encephalitis, the diagnosis can be made from a blood test or a lumbar puncture. Depending on the stage of the disease, different tests may be used, such as PCR Acronym for polymerase chain reaction, is a technique used in laboratories to amplify DNA fragments. This technique is used for rapid diagnosis of the presence of pathogens, for example. or Serology This involves measuring antibodies (produced by the body in response to the presence of a pathogen) in a blood sample.

How is the disease treated and prevented?

There is no specific treatment for Japanese encephalitis; treatment is symptomatic. 
Vaccines are available and widely used in countries where Japanese encephalitis is Endemic Persistent circulation of a disease or Pathogen Micro-organism capable of causing disease. in a population or geographical area. . Depending on the type and length of stay, vaccination is sometimes also recommended for travellers. Prevention also involves avoiding mosquito bites.