Japanese EncephalitisA Mosquito-borne Virus

What are Viruses?

• Non-living structures containing genetic material. (PBS, 2007)

• First discovered in 1898 by Loeffler and Frosch (UCMO, 1993)

• Require host cells to reproduce (PBS, 2009)

• Function by inserting their unique code into the nucleus of the host, taking over the functions and ultimately destroying the cell

Japanese Encephalitis

• Single strand RNA virus• Related to West Nile• Prevalent in Asian countries• Occurs in wet, rural areas• Transmitted mainly by mosquitoes

Transmission

• The JE virus (JEV) is mainly transmitted by the mosquito Culex tritaeniorrhynchus, which prefers to breed in irrigated rice paddies (CDC, 2009)

• Water birds may also carry the disease, and it often infects pigs

• Raising pigs is a risk factor!• Spreads through bird and human migration, and

internationally through wind-blown mosquitoes

Symptoms

First Infection Serious Infection

Mild or No Symptoms

Seizures

Fever Mental Illness

Headache Muscle Failure

Nausea and Diarrhea Inability to Speak

(NHS, 2010)

Prevalence

• Occurs in South Asia, Southeast Asia, East Asia and the Pacific

• Has been carried by mosquitoes to Australia• Carried most specifically by Culex tritaeniorrhynchus,

which breeds in rice paddies (CDC, 2009)• Annual deaths (human) 10,000-15,000 • 20%-30% mortality rates• 30%-50% of survivors suffer residual neuropsychiatric

problems (CDC, 2009)

Prevention

• Basically, • Use nets, repellent, and wear long and loose clothing• Efforts only relevant for visits to endemic areas for > 1

month during the JE season, or in areas with ongoing outbreak (CDC, 2012)

• A vaccine is obtainable and advised for those whose situation matches the one described above

Treatment

• There is NO SPECIFIC TREATMENT• STILL, there are measures taken to control symptoms and

prevent complications• Therapy may be necessary, and is supportive.• Patients may require:

• Feeding• Airway management• Anticonvulsants• Mannitol (decreases intracranial pressure) [Medscape, 2012]

• In ICU cerebral perfusion pressure (mean minus arterial) is maintained thru modulation (Medscape, 2012)

Personal/Global Effects

• For patients not covered by health insurance, vaccines for prevention can be $450-$1,100

• For those with insurance, it can be as low as $10-$40 (costhelper, 2010)

• Global impact in 2002 was 709,000 disability-adjusted life years (DALYs) [CDC, 2009]

• The disease is dynamic, because some cases may be very mild, whereas others cause irreversible neurological damage

• Affects mostly tourists and those stationed in rural areas, typically rice farmers, in many Asian countries

Documentation

• Emiliani, C. (1993). Introduction to the Viruses. UCMP. [accessed 12 March 2013]. Retrieved from http://www.ucmp.berkeley.edu/alllife/virus.html

• Costhelper. (2010). Japanese Encephalitis Vaccine Cost. [accessed 12 March 2013]. Retrieved from http://health.costhelper.com/japanese-encephalitis-vaccine.html

• Jani, A. A. (2012). Japanese Encephalitis Treatment and Management. Medscape. [accessed 12 March 2012]. Retrieved from http://emedicine.medscape.com/article/233802-treatment

• Erlanger, T.E., Weiss S., Keiser J., Utzinger J., Wiedenmayer K. (2012). Past, Present, and Future of Japanese Encephalitis. CDC. [Accessed 12 March 2012]. Retrieved from http://wwwnc.cdc.gov/eid/article/15/1/08-0311.htm

• NHS. (2012). Japanese Encephalitis. [accessed 12 March 2012]. Retrieved from http://www.nhs.uk/Conditions/Japanese-encephalitis/Pages/Introduction.aspx

• CDC. (2012). Japanese Encephalitis. [accessed 12 March 2012]. Retrieved from http://www.cdc.gov/japaneseencephalitis/prevention/index.html