A recurrent disease that has plagued the United States for several years now is the West Nile virus. It has caused a drain on the country’s health resources as well as a constant problem to effectively control its outbreaks. The disease shows many effects that vary from person to person, and as such is a hassle to treat. Mackenzie, Gubler, & Petersen, (2004) suggested that the West Nile Virus derives its name from the West Nile district of Uganda.
It is also known as Kunjin virus and is widely distributed throughout Africa, Middle East, parts of Europe and the former Soviet Union, South and central Asia , Australia, North America, Caribbean and Mexico (C. G. Hayes, 2001). The West Nile virus is a zoonotic disease. Zoonotic diseases are disease that can be transmitted to humans from animals. This virus is a close relative of St. Louis encephalitis virus and is transmitted by mosquitoes primarily of the Culex genus (Weir & Shapiro, 2004). The West Nile Virus (WNV) causes avian encephalitis (Kreil, 2004).
In humans, symptoms could occur within 3 to 15 days after bite of the infected mosquito. Symptoms include mild illness, fever, headache, maculopapular rash, conjunctivitis (irritation of the eye); gastrointestinal symptoms; and lymphadenopathy. Meningitis, West Nile encephalitis particularly the elderly and myelitis may also occur. It could be fatal. However only less than one percent of infected persons will develop severe illness (Briese & Bernard, 2005). The west nile virus has common epidemic recurrence and as such is a serious consideration to a countries health assessment.
It’s unpredictable effects make it difficult to fully control its outbreak. Thus this research project aims to find out what causes these effects so that study on their treatment and prevention can be undergone. The West Nile virus is a member of the family Flaviviridae (genus Flavivirus) that requires a blood-sucking arthropod to complete its life cycle. (Mackenzie et al. , 2004). The main course of the disease is a bird-mosquito-bird cycle, with birds as the primary amplifying hosts(“West Nile virus: what’s the buzz?,” 2000).
Vertebrate hosts like humans and horses are incidental hosts and play a minor role in the transmission of the disease. Bird migration, random bird dispersal movements or both were responsible for the westward spread of the virus (Briese & Bernard, 2005). Mosquitoes mostly of the Culex spp. transmit WNV. The main mosquito species are Cx. univittatus in Afica and the middle East; Cx. pipiens, Cx. modestus and Coquillettidia richiardii are important in Europe; Cx. tritaeniorhynchus, Cx. vishnui, and Cx.
Quinquefasciatus in Asia; Cx. pipiens, Cx. quinquefasciatus, Cx. restuans tarsalis in North America. Non-culex that are also important in some areas are Aedes albocehalus or Mimomyia spp. in Africa and the Middle East. (Mackenzie et al. , 2004). Some factors that affect the spread of the virus include weather, presence of infected vectors, and exposure to the vectors, susceptible hosts, and presence of alternate hosts (wildlife). The warm weather months favor spread of the viruses when mosquitoes are most active.
This usually occurs in the spring and lasting until the first hard frost. At high risk of getting infected are older persons 50 years of age or older (Gea-Banacloche et al. , 2004). Risk increases about 1. 5-fold for each decade of life. A person 80-90 years old has a risk 30 times greater than a child younger than 10 years old. (Mackenzie et al. , 2004) The factors that cause the emergence, resurgence and spread in new habitats and environments are complex. Some these are natural such as bird migration and most are due to human activities.
The human activities that contribute to its spread include changing land use, water impoundments and transportation. These changed the epidemiological patterns. Management of West Nile Virus is largely directed towards the surveillance and population control of the mosquito vectors, and public education campaign (Allison, Gottdenker, & Stallknecht, 2005). Surveillance which consisted of collection and testing of over wintering Culex mosquitoes were done by the New York State Department of Health in January-February 2000 to determine the transmission cycle in the spring of 2000.
(“Update: Surveillance for West Nile virus in overwintering mosquitoes–New York, 2000,” 2000). Public education is creating awareness about the risk of the disease through graded warnings as was done in Connecticut. The education campaighn also included the use of personal protective behaviors (PPBs) and peridomestic mosquito control to reduce the risk for mosquito bites. (“Knowledge, attitudes, and behaviors about West Nile virus–Connecticut, 2002,” 2003)