Viruses 3 Emerging and Bioterrorism BLH Flashcards
Enterovirus 68
- Non-polio enterovirus
- Usually causes runny nose, sneezing, cough, and body and muscle aches
- Severe symptoms may include wheezing and difficulty breathing
- Acute flaccid myelitis -115 children in 34 states have developed polio-like paralysis in an arm or a leg and there is an epidemiologic putative association with enterovirus 68 B1 strain
Viral Hemorrhagic fevers
- RNA viruses
- Arenaviridae
- Filoviridae
- Bunyaviridae
- Flaviviridae
- Rhabdoviridae
- Have animal or insect host
- Usually rodent or insect vector
- Human to human transmission with Ebola, Marburg and Lassa fevers
- Systemic infections involving CNS
Arenaviridae
South American hemorrhagic fever viruses and Lassa Fever
Filoviridae Overview and Subtypes
(Ebola Hemorrhagic Fever)
•-ssRNA viruses (Filoviridae)
1) Ebola virus (Zaire ebolavirus)
2) Sudan virus (Sudan ebolavirus)
3) TaïForest virus (TaïForest ebolavirus, formerly Côte d’Ivoire ebolavirus)
4) Bundibugyovirus (Bundibugyoebolavirus
Bunyaviridae
Rift Valley fever & Crimean-Congo hemorrhagic fever
Flaviviridae
Dengue hemorrhagic fever
Rhabdoviridae
Bas-Congo virus hemorrhagic fever
Filoviridae or Ebola Transmission
- Fruit bats or primates are the most likely reservoirs
- Person-to-person transmission via blood or body fluids (urine, saliva, sweat, feces, vomit, breast milk, and semen)
Filoviridae or Ebola Sx, DX and RX
- Sx-Fever, severe headache, muscle pain, weakness, fatigue, diarrhea, vomiting, abdominal pain, hiccups, unexplained hemorrhage
- Symptoms appear 2 to 21 days after exposure
- 25-90% mortality
- Dx-ELISA and RT-PCR for viral proteins or RNA
- Rx –supportive
Dengue Fever Overview
Flavivirus; +ssRNA with no envelope
- Caused by any of four closely related RNA viruses, or serotypes: dengue 1-4
- Dengue is transmitted between people by the mosquitoes Aedesaegyptiand Aedesalbopictus
- 2009/10 –Key West outbreak 88 cases
- 2013 outbreak Martin county Florida 28 cases
Classi Dengue Fever
“break bone fever,” -acute onset of high fever 3–14 days after the bite, frontal headache, retro-orbital pain, myalgias, arthralgias, hemorrhagic manifestations, rash, and low white blood cell count
Dengue Hemorrhagic Fever
Fever lasting 2–7 days with any hemorrhagic manifestation, thrombocytopenia, evidence of increased vascular permeability. Can have severe abdominal pain, CNS symptoms, shock.
Dengue DX and RX
- Dx-virus isolation or detection of DENV RNA in serum
- Rx-supportive, IV fluids, Dextran 40
Powassan Virus Overview
- Flavivirus(similar to deer tick virus); +ssRNA
- Reservoir varies by tick species (mostly small mammals)
- Tick (Ixodes) borne virus found mostly in Canada, northeast and Great Lakes regions, and Russia
Powassan Virus SX, DX and RX
- 1 week to 1 month incubation and infections range from asymptomatic to encephalitis and meningitis
- Fever, headache, vomiting, weakness, confusion, loss of coordination, speech difficulties, and seizures
- 50% develop permanent neurologic deficits
- 10% die
- Dx -POW virus-specific IgM antibody in serum or CSF (performed at the CDC), PCR
- RX -supportive
West Nile Virus Overview
Flavivirus-ssRNAwith no envelope
- The West Nile virus emerged in New York (1999)
- Present now throughout most of the U.S.
- Common in Africa, Asia, and the Middle East
- Carried by bird populations
- Vector -mosquito (lots of different species)
- Human to human via blood or milk
West Nile Virus SX, DX and RX
- Acute viremia
- Usually subclinical infections or viral syndrome (20%)
- Maculopapular rash in 50% with viral syndrome
- Meningoencephalitis (<1%) usually mild, 10% fatal
- Dx –WNV antibody testing, culture, PCR
- Rx-supportive
Chikungunya Virus
- Late 2013-first local transmission of chikungunyavirus in the Americas (St. Martin)
- Symptoms begin 3–7 days after being bitten by infected Aedesmosquitos
- Most common symptoms are fever and joint pain
- Self limited (1 wk. most symptoms and months for joints)
- Dx-serum or plasma to detect virus, viral nucleic acid, or virus-specific immunoglobulin (Ig) M or neutralizing antibodies
- Rx-supportive
SARS Virus
- Severe acute respiratory syndrome (fever >100, flu symptoms)
- Severe acute atypical respiratory syndrome due to a novel coronavirus
- 2002/3 –first cases in Asia spread globally (29 cases in U.S.A.)
- 8,098 people worldwide, 774 died
- Spread via respiratory droplets and can lead to ARDS
- No cases since 2003 outbreak
- Reservoir appears to be birds and small mammals (bats?)
- Dx-antibodies to SARS-CoV, culture or PCR
MERS Coronavirus Overview
- Middle East Respiratory Syndrome Coronavirus
- 2012 –first cases in Jordon and Saudi Arabia (2 imported cases from Arabian Peninsula to U.S.A. in 2014)
- Spread via saliva, respiratory droplets
- 58% mortality
- May have originated in bats and transmitted to camels
MERS Coronavirus SX, DX and RX
- Asymptomatic to severe acute respiratory syndrome (fever and pneumonia) in person coming from Arabian peninsula or in close contact with MERS patient
- Dx-antibodies to MERS-CoV, culture or MERS-COVRRT-PCR
- Rx-supportive
Bunyaviridae Overview
- Enveloped -ssRNA
- Virus alternates between vertebrates and arthropod vectors
- California encephalitis
- La Crosse encephalitis
- Crimean-Congo hemorrhagic fever
- Rift Valley fever
- Hantavirus
California Encephalitis
Bunyaviridae
California encephalitis virus via mosquitos in Kern and Marin counties, CA
La Crosse Encephalitis
Bunyaviridae
La Crosse virus via mosquitos in Eastern U.S.
Crimean Congo Hemorrhagic Fever
Bunyaviridae
Crimean-Congo hemorrhagic fever virus via ticks or human body fluids; reported in Africa, Asia, Europe and Middle East
Rift Valley Fever
Bunyaviridae
Rift valley fever virus via mosquitos, originally in Kenya now in Africa and Middle East
Hantavirus
Bunyaviridae
worldwide
- Hemorrhagic fever with renal failure –Asia and Europe
- Pulmonary syndrome -spread via aerosolized rodent excrement causing pulmonary edema with 40% mortality; in U.S. around “four corners” region (Arizona, Colorado, New Mexico and Utah)
- Deer mice is carrier in Four Corners region
- Dx –serology to “Sin Nombre” virus; p.k.a”Four Corners virus”
- Rx -supportive
Bioterrorism CDC Category A
•Category A -can be easily disseminated or transmitted from person to person; result in high mortality rates and have the potential for major public health impact; might cause public panic and social disruption; and require special action for public health preparedness.
- Anthrax (bacillus anthracis)
- Botulism (clostridium botulinumtoxin)
- Plague (yersiniapestis)
•Smallpox (variolamajor)
- Tularemia (francisellatularensis)
- Viral hemorrhagic fevers (filoviruses[e.G., Ebola, marburg] and arenaviruses [e.G., Lassa, machupo])
Bioterrorism Category B
•Category B -moderately easy to disseminate; result in moderate morbidity rates and low mortality rates; and require specific enhancements of cdc’sdiagnostic capacity and enhanced disease surveillance.
•Brucellosis (brucellaspecies)
- Epsilon toxin of clostridium perfringens
- Food safety threats (e.G., Salmonellaspecies, escherichiacoliO157:H7, shigella)
- Glanders (burkholderiamallei)
- Melioidosis (burkholderiapseudomallei)
- Psittacosis (chlamydia psittaci)
- Q fever (coxiellaburnetii)
•Ricin toxin from ricinuscommunis(castor beans)
- Staphylococcal enterotoxin B
- Typhus fever (rickettsia prowazekii)
- Viral encephalitis (alphaviruses [e.G., Venezuelan equine encephalitis, eastern equine encephalitis, western equine encephalitis])
- Water safety threats (e.G., Vibrio cholerae, cryptosporidium parvum)
Bioterorrism Category C
•Category C -emerging pathogens that could be engineered for mass dissemination in the future because of availability; ease of production and dissemination; and potential for high morbidity and mortality rates and major health impact.
•Emerging infectious diseases such as Nipahvirus and hantavirus
Anthrax Overview
- Bacillus anthracis
- Large gram + bacillus in chains
- Infection via dormant endospores
- Spores usually found in soil
- Cutaneous anthrax (skin cuts/abrasions)
- Gastrointestinal anthrax (ingestion)
- Pulmonary anthrax (inhalation)
- Dx-gram stain, PCR, immunofluorescence
Anthrax RX and Prevention
- Rx-antibiotics
- Rx-3 concurrent antimicrobials
•Anthrasil(anthrax immune globulin intravenous [human]) for inhalational anthrax
- Prevention –vaccine
- Pasteur’s second vaccine (1881)
•Ava/BioThrax(used for combatants)-antigenic portions from culture filtrates of toxigenic (avirulent) nonencapsulated mutant B. anthracis
Poxviruses (Orthopoxviruses) Overview
Smallpox
•Variolavirus-dsDNA with envelope; large and brick shaped
- DNA-dependent RNA polymerase required since it replicates in the host cytoplasm
- Smallpox officially declared eradicated by the WHO in 1980
- The lack of an animal reservoir made eradication of human disease possible
•Respiratory transmission (mouth and throat lesions) then transient viremia to internal sites, then 2ndviremia to skin (synchronous rash macular→papular→ vesicular→pustular→crusts)
Forms of Smallpox
- Variolamajor (Asia and India) -most common with 50% mortality rate
- Variolaminor (South America) -less common with < 1% deathrate
- Hemorrhagic black pox-fatal with smooth skin with petichiae (occasionally develop vesicles), sub-conjunctival and internal bleeding
Smallpox DX, RX, and Prevention
- Dx –Characteristic deep skin lesions with centrifugal pattern (mostly face and extremities) and synchronous development on individual areas of the body
- B-type intracytoplasmic inclusions (Guarnieribodies)
- Rx-Smallpox vaccination within three days of exposure
- Prevention –Edward Jenner, 1796, inoculated material from cowpox lesion
•Smallpox vaccine –live vaccinia virus preparation
