WEST NILE VIRUS

Information about WEST NILE VIRUS

Published on January 13, 2012

Author: nishikaa

Source: authorstream.com

Content

West Nile Virus: West Nile Virus Presentation By: NISHIKA BHAN M.Sc. M.T. 1 st Semester PowerPoint Presentation: West Nile virus (WNV) is an important arthropod borne flavivirus ; usually causes a mild infection called West Nile fever (WNF) in humans and horses. West Nile Encephalitis is an infection of the brain that is caused by the West Nile virus . " Encephalitis " means inflammation of the brain. Virus classification: Virus classification Group: Group IV ((+)ssRNA) Family: Flaviviridae Genus: Flavivirus species: west nile virus MICROSCOPIC STRUCTURE OF West Nile Virus : MICROSCOPIC STRUCTURE OF West Nile Virus STRUCTURE OF WEST NILE VIRUS: STRUCTURE OF WEST NILE VIRUS are spherical particles are 50 nm in diameter consist of a membrane envelope and a dense core. virus contains a positive, single-stranded RNA genome that is packaged within the core protein C. The viral envelope protein is composed of envelope E and membrane M proteins that are embedded in a lipid bilayer. The RNA strand is held within a nucleocapsid formed from 12 kDa protein blocks. GENOMIC STRUCTURE: GENOMIC STRUCTURE Genetic material – ss RNA (11,000 - 12,000 nucleotides long) Genes encode 3 structural proteins and 7 non-structural proteins. 3 structural proteins : C, M, E. 7 non-structural proteins : 1, 2A, 2B, 3, 4A, 4B and 5. History of West Nile virus: History of West Nile virus WNV was first isolated from a feverish 37 year old woman at Omogo in the West Nile District of Uganda in 1937 , the virus is commonly found in Africa, West Asia, and the Middle East. West Nile virus had not been previously reported in the U.S. prior to an outbreak in New York in September 1999. According to the U.S. Center for Disease Control and Prevention (CDC), 28,961 confirmed and probable cases of West Nile virus disease were reported from 1999 to 2008. In 41% of the cases, patients developed neuroinvasive disease, the most severe form of West Nile virus infection. Neuroinvasive disease was most prevalent in the west north central and mountain states, with 63% of cases being reported from 10 states: Arizona, California, Colorado, Illinois, Louisiana, Michigan, Mississippi, Nebraska, South Dakota, and Texas. Habit & Habitat: Habit & Habitat Found in both tropical and temperate regions. Infects birds . Is also known to infect humans , horses , dogs , cats , bats , chipmunks , skunks , squirrels , and domestic rabbits . Symptoms : Symptoms Produces 3 different outcomes in humans: an asymptomatic infection; a mild febrile syndrome ; and a neuroinvasive disease termed meningitis or encephalitis. PowerPoint Presentation: Asymptomatic infection : infection with no symptoms. Febrile stage : incubation period of (2 – 8) days followed by fever, headache, chills, diaphoresis (excessive sweating), weakness, lymphadenopathy (swollen lymph nodes), drowsiness, pain in the joints and symptoms like those of influenza or the flu. Some patients experience gastrointestinal symptoms including nausea, vomiting, loss of appetite, or diarrhea. Symptoms are generally resolved within (7 – 10) days, although fatigue can persist for some weeks & lymphadenopathy up to 2 months. PowerPoint Presentation: Neuroinvasive disease : infection and invasion of nerve cells. The spinal cord is infected. Also leads to hepatitis, myocarditis, nephritis, pancreatitis, and splenomegaly. Transmission : Transmission VECTOR : 2 Mosquito species - Aedes albopictus and Culex spp. ( Cx. pipiens (Eastern US), Cx. tarsalis (Midwest and West), Cx. quinquefasciatus (SE) & Cx. vishnui (India & Pakistan). HOSTS : Birds (the American robin and the American crow ) TRANSMISSION: TRANSMISSION Susceptibility : Susceptibility Direct human-to-human transmission: by occupational exposure , conjunctival exposure to infected blood. Novel transmission methods : through blood transfusion, organ transplant, intrauterine exposure, and breast feeding. Recent outbreaks : Recent outbreaks United States : 1999 – 2001 : CDC confirmed 149 WNV infections, including 18 deaths. 2002 : Total 4,156 cases reported, including 284 fatalities. 13 cases were contracted through blood transfusion. 2007 : 1,227 cases of wnv neuroinvasion disease and 117 deaths occurred. Canada : 2004 : 26 cases reported including 2 deaths. 2005 : 239 cases including 12 deaths. Israel : 2000 : CDC confirmed 417 cases, out of which 57.9% were encephalitis, 24.4% febrile disease and 15.9% meningitis. 33 deaths were noticed. Control : Control Mosquito control : By elimination of mosquito breeding sites, Larviciding active breeding areas, and Encouraging personal use of mosquito repellents. Defensive measures : Public is encouraged to spend less time outdoors, Wear long covering clothing. Apply insect repellant that contains DEET (N,N-diethyl-meta-toluamide), Ensure that mosquitoes donot enter buildings. Spray clothing with repellents containing DEET since mosquitoes may bite through thin clothing. Take preventive measures in and around the house by repairing door and window screens, use air conditioning, and reduce breeding sites (eliminate standing water). If you find a dead bird, the CDC recommends that you not handle the carcass with bare hands. Contact the local health department for disposing of the carcass. Laboratory Diagnosis : Laboratory Diagnosis (MAC-ELISA) : stands for IgM antibody capture enzyme-linked immunosorbent assay. Using this assay, virus-specific IgM can be detected in CSF and serum specimens received from WNV-infected patients. Because IgM antibody does not readily cross the blood-brain barrier, IgM antibody in CSF strongly suggests acute CNS infection. RT-PCR : stands for reverse transcription polymerase chain reaction. Directly amplifies and shows the presence of virus in the infected samples . Treatment : Treatment The drug discovered is called the AMD3100 . It works by targeting the blood-brain barrier, which keeps infection-fighting inflammatory cells out of the brain. Morpholino is a molecule used to modify gene expression. It acts by "steric blocking", binding to a target sequence within an RNA and simply getting in the way of molecules which might otherwise interact with the RNA. Ribavirin is an antiviral drug which interferes with RNA metabolism required for viral replication. REFERENCES: REFERENCES en.wikipedia.org/wiki/ West _ Nile _ virus www.cdc.gov/ westnile / www.medicinenet.com › ... › west nile encephalitis index icmr.nic.in/ijmr/2003/0901.pdf Dunham, Will. "U.S. West Nile Virus Cases, Deaths Rose in 2006." <http://www.reuters.com/article/domesticNews/idUSN0718979120070607>. Kennedy, Kristy. "Calming West Nile Fears." American Academy of Paediatrics. Sept. 2002. <http://www.aap.org/family/wnv-sept02.htm>. THANK-YOU: THANK-YOU

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