MIC 301 EMERGING AND RE-EMERGING VIRAL DISEASESEMERGING AND RE-EMERGING VIRAL DISEASESFACTORS CONTRIBUTING TO EMERGING AND RE-EMERGING DISEASESSlide 4LECTURE OUTLINEMany of these viruses are dangerous and need containment (e.g. Biosafety level 4 [BSL4]) or BSL3 labsBIOSAFETY SUITS (use for BSL3)NIPAH VIRUSParamyxovirusCLINICAL SYMPTOMS OF NIPAH VIRUS INFECTIONDengue and West Nile VirusesFlavivirusTransmission of ArbovirusesTransmission of FlavivirusesDENGUEDengue fever, showing the rash Dengue Hemorrhagic Fever is much more seriousDengue distributionWest Nile virusA mystery illness in birds, August 1999 In the New York City AreaA mystery illness in birds, September 1999 Disease spread in one monthMystery illness in birds (crows) identified as caused by WEST NILE VIRUSHANTAVIRUSESBunyavirusSummer of 1993: a mystery illness affects the southwest USMystery illness of 1993 identifiedThe reservoir for HPS is P. maniculatis (deer mouse)CLINICAL SYMPTOMS OF HANTAVIRUS PULMONARY SYNDROME (HPS)Why HPS emerged in 1993? Snow in the Sierras led to increase in the deer mouse populationThere are major annual outbreaks in China of Hemorrhagic Fever with Renal Syndrome caused by hantaviruses (>200,000 cases) The major virus is Hantaan virusEBOLA and MARBURG VIRUSESFilovirusEbola and Marburg virusesSlide 33Outbreak of Ebola in Angola-burying dead bodiesSlide 35Chikungunya virusSlide 37Emerging viruses- 2015Emerging virusesMIC 301EMERGING AND RE-EMERGINGVIRAL DISEASESDr. John [email protected] of Microbiology and ImmunologyEMERGING AND RE-EMERGINGVIRAL DISEASESDefined as infections that have newly appeared in apopulation or have existed but are rapidly increasing inincidence or geographic range.Global resurgence in zoonotic viral diseases (transmitted by animalsto humans). About 75% of emerging agents are zoonotic. Examples of emerging and re-emerging diseases/viruses: HIV/AIDS, SARS, Ebola virus, Nipah virus, avian flu(1997-China-still around in SE Asia) and H1N1 swine flu (2009 Mexico), monkeypox virus in humans in USA in 1970 (from African monkeys and African squirrels- host for monkeypox), dengue, Ebola, Marburg, hantaviruses, chikungunya .FACTORS CONTRIBUTING TO EMERGING AND RE-EMERGING DISEASESSpecific factors precipitating disease emergence can be identified invirtually all cases, such as:Ecological and Environmental-interaction between organisms and their natural environmentExample: farm animals (pigs/chickens/ducks; avian flu (H5N1/H9N7)Demographic- populations that may be at increased risk of contact with previously unfamiliar agent or its natural host to promote disseminationExample: movement of people (air travel); SARS from Honk Kong to TorontoFACTORS CONTRIBUTING TO EMERGING AND RE-EMERGING DISEASESVIRAL AGENT FACTORSDengue virus, West Nile virus, transportation (travel),SARS (severe acute respiratory syndrome) urbanization/migration Marburg virus importation of monkeys to Marburg, Germany in 1967(no cases in USA, yet)Hantaviruses environmental changes in USA In S. Korea,(Hantaan river, S. Korea) increasing contact with rodent hosts (expansion of rice fields-rodent area)HIV/AIDS travel, sexual transmission, iv drug use, mother to childLECTURE OUTLINENipah virusDengue and West Nile viruses HantavirusesEbola and Marburg virusesChikungunya virusAlready covered:HIV/AIDSAvian influenza H1N1 2009 flu (so-called “swine flu”)Many of these viruses are dangerous and needcontainment (e.g. Biosafety level 4 [BSL4]) or BSL3 labsBIOSAFETY SUITS (use for BSL3)NIPAH VIRUSMember of the Paramyxoviridae (negative sense RNA genome)(Like measles virus)First reported in Malaysia in 1999. Outbreak of fatal febrile encephalitis and respiratory illness (mainly in adult men)Re-emerged in Bangladesh in 2001 with high mortality rate.Reservoir- fruit bat (flying fox)Transmission- 1) to humans via intermediate host, pig or pig products 2) human to humanParamyxovirusCLINICAL SYMPTOMS OF NIPAH VIRUSINFECTION1. Incubation period: 3-14 days2. Followed by drowsiness and disorientation and mental confusion. Some patients may experience respiratory illness during this stage.3. Encephalitis can progress to coma and death in 24-48 hours4. Also causes serious disease in pigsVaccine: noneAntiviral- ribavirin lessens mortalityDengue and West Nile VirusesBOTH: 1. belong to the family Flaviviridae (most of which are Arboviruses [ARthropod-BOrne])2. ss-RNA (+ sense) viruses (replication similar to poliovirus)3. transmission via various birds and animals (reservoirs), with mosquito vectors4. no vaccine 5. no anti-viral agentsFlavivirusTransmission of ArbovirusesTransmission of FlavivirusesDENGUE First observed in ~1780 in Asia, Africa and North AmericaA very common disease worldwide that is re-emerging asmosquitoes (vector) spread (300 million people infected annually)Reservoirs of dengue virus are humans and primatesClinical symptoms:- dengue fever (febrile rash) and dengue hemorrhagic fever (DHF) or shock syndrome (DSS)-DHF and DSS are serious illnesses that occur when people get infected serially with 2 different strains; high mortalityPrevention: avoid mosquitoesDengue fever, showing the rash Dengue Hemorrhagic Fever is much more seriousDengue distributionWest Nile virusA mystery illness in birds, August 1999In the New York City AreaA mystery illness in birds, September 1999Disease spread in one monthMystery illness in birds (crows) identified as caused by WEST NILE VIRUSFirst case in 1937 in West Nile district of Uganda.Since spread worldwide-Africa, Europe, Middle East andNYC in 1999.How did the virus get to NYC? - via mosquitoes and birds(reservoirs) from Middle East and or Europe?Spread to all lower 48 states in USA, as well as Canadaand Mexico in several years since 1999.2014: 2,122 cases, 85 deaths. CA, TX 300+ cases; AZ, CO, LA, NE.Clinical symptoms:Most infections are asymptomatic, but small numbercause encephalitis (can be fatal in the elderly)No human to human transmission - level of virus too lowNo FDA approved vaccineHANTAVIRUSESFamily: BunyaviridaeVirus: ss-RNA (-) sense, 3 segmentsName: First isolated (1978) in a field mouse near the Hantaan River, S. Korea, causing hemorrhagic fever with renal syndrome (HFRS), with up to 10% case/fatality; virus spread directly from small animals, through inhalation of dried fecal material and urine.Since that time, the virus has