Japanese Encephalitis
Disease Name:- Japanese Encephalitis
Species Affected:
Equine, Porcine and many mammal species including human are affected by the
disease.Bovine,Ovine, Caprine and Canine are less affected species. However, these
domesticated animals including pigs do not show disease symptoms and they remain carrier of
the virus of the disease.
About the Disease:
Japanese encephalitis is an acute arbovirus disease affecting mainly pigs, horses and humans. It is
a zoonotic disease having its natural cycle in wild or domesticanimals and haemotophagus
arthropods. Japanese encephalitis infection causes abortion, stillbirths or mummified foetuses in
sows, and feverand encephalitis with deaths in piglets, horses and humans.Swine acts as amplifying
host and has very important role in epidemiology of the disease. Cattle, horses and human are dead-end
hosts and disease manifested as fatal encephalitis. This disease is an OIE Reportable Disease as in
the Multiple Species Disease Category. In countries where it is endemic, this virus causes
reproductive losses in swine and encephalitis in horses.
Animals Affected:
Pigs, horse and donkeys are mostly affected. This virus can also infect other domestic animal
including cattle, goat, sheep, and dogs.Horses are the primary affected domestic animals of
Japanese encephalitis though essentially a dead-end host.Several species of bat are susceptible to
this disease.
Cause:
Japanese encephalitis is caused by a Flaviviridae virus ofgenus flavivirus, a RNA virus which is
transmitted by the bite of an infected mosquito.Amongst the most important vectors of this
disease are the mosquitoes Culextritaeniorhynchus and Culexvishnui.Japanese Encephalitis
virus infects a very wide range of animal species without causing disease.
Source of infection:
Japanese encephalitis is spread through the bite of infected mosquitoes (vector). Some animals,
especially infected pigs and birds, can have large amounts of the virus in their blood and serve as
a major source of the virus (reservoir) for mosquitoes. Domestic pigs and wild birds (herons) are also
known to be reservoirs of the virus. Men get infection through the bites of these mosquitoes.
Symptoms:
The symptoms in pigs may be:
1. Fever up to 104◦F to 105◦F
2. Loss of Appetite
3. Depression
4. Photophobia
5. Tremor
6. Ataxia
7. Hyperaesthesia
8. Difficulty in respiration
9. Abortion, stillbirths or mummified foetuses
10. Sometimes death
In horses,
1. Fever,
2. Jaundice
3. Nervous signs of depression and incoordination or hyper-excitability.
Many species of animals that become infected, such as cattle, dogs, cats, and birds show no signs of
illness.
Control and Management:
Control of Japanese encephalitis should be followed by:
1. Controlling insect vectors by using insecticide in the breeding place.
2. Preventing exposure of susceptible animals to JE virus infected mosquitoes.
3. Proper management of livestock farming including piggery farming so as to limit the
amplification of virus in these animals.
4. Piggery farming should be away from humane dwelling areas.
5. Protecting susceptible animals and humans from disease by vaccination.
Vaccines:
A live attenuated vaccine is in human are widely available, however, there has been limited
production of animal vaccine when indicated for domestic animals.
Meteorological Occurrence:
JE virus is widespread throughout temperate and tropical Asia. It is most often associated with
areas of intensive rice farming and swineproduction.Transmission of the disease is most
likelyduring the summer months in temperate areas and during the rainy and high humid in
tropical areas, when the mosquito populations are the highest.