Viral and Prion Diseases

• Influenza
• Rabies
• EEE
• Mumps

Transmissible Spongiform Encephaopathies (TSE)

• Mad Cow Disease
• Scrapies
• Kuru
• Chronic Wastruing Disease
• Creutzfeld-Jacob Disorder

orthomyxovirus

• segmented, (-) sense ssRNA
• capsid
• envelope

• A,B,C
• are classifies by antibody response to viral glycoprotiens.

• 17 Hemagluttins (HA), attach to host cell
• 9 Neuraminidase (NA), release from host cell

• Virus binds to and enters epithelial cells via hemogluttin proteins.
• Viral replication
• Viral protein synthesis
• viral release and spread

• Attachment via HA glycoproteins spikes to host sialic acid receptors
• Virus undergoes endocytosis

• NA proteins cleave sialic acid receptors
• Virus builds envelope as it buds through hosts cell membrane.

• No cross-species transmission because of restrictions by virus subtype.
• Airborne, Droplet
• Source (animal host) transmits viruses before onset of symptoms

• Involves point mutations that result in mild changes in the characteristics of viral vurface proteins
• When sufficient Drift occurs, any previously developed host antibodies will be ineffective against the new "drifted"virus type
• Ex. seasonal Flu

• involves dramatic changes in viral characteristics due to Gene reassortment with other viral strains
• Ex. Pandemics : H1N1 2009 "swine flu", quadruple reassortment virus (contained 4 different pieces of DNA)

• typically 1-7 days
• fever
• chills
• headache
• cough
• sore throat
• extreme fatigue
• body aches

• pneumonia
• bronchitis
• sinus and ear infections

• Rest
• Hydrate
• Antiviral medications when necessary
• Supportive therapy

• Seasonal vaccines
• Flu shot (contain the killed virus)
• FluMist Nasal spray (contain live attenuates virus)

• wash hands frequently
• cough into elbow
• properly dispose of used tissue
• stay home and rest

Rhabdovirus

• non- segmented, (-) sense ssRNA
• capsid
• envelope

• requires RNA-dependent RNA polymerase for reverse transcription
• cytopathic effects: negri bodies (viral junk left over found in nervous tissue)

• has to replicate in nervous tissue in brain
• Being directly bitten by a rabid animal
• saliva is infected
• Iatrogenically (corneal transplant)

can infect humans, terrestrial and aquati,  livestock and crops

• varies 13 days to 2 years
• time if effected by the distance between the wound and the brain

• Flu-like
• numbness
• anxiety
• confusion
• agitation
• hollucinations
• insomnia
• delerium
• nearly always deadly

• wound care
• human rabies immune globulin (HRIG)
• vaccine

• vaccine
• animal vector control

• cats(us)
• dogs( worldwide)
• Bats

• Eastern Equine Encephalitis virus
• (+) ssRNA genome

• Reguires transmission from primary vertebraet host (birds) to secondary host (human, horse (accidental host)) via blood sucking arthropods (mosquitoes)
• (few mosquito species are capable of transmitting EEEv)

• US about 6 cases/yr.
• most common in and around freshwater hardwood swamps( late july through september)

• Systemic
• Encenphelitic

Abrupt onset of chills, fever malaise, joint and muscle pain (on CNS)

abrupt in infants; after few days of systemic ilness in oler children and adults

Fever, headache, iritability, restlessness, drowsiness,anorexia, vomiting, diarrhea, cyanosis, convulsions and coma

Brain dysfunction, seizures, paralysis

1/3

none

• no vaccine
• control vector
• avoid high risk areas

• people who engage in outdoor work and recreational activities
• >50 yrs and <15 yrs are at greatest risc of severe infection

Rubella paramyxovirus

• direct
• droplet
• fomites
• and extremely contagous

• low-grade fever
• headache
• muscle weakness
• stiff neck
• loss of appetite
• swelling (lymphnodes)
• tenderness

rare severe complications include encephalitis, menengitis, sterility in men( mostly during adolescence), deafness ( permanent or temp.)

• supportive therapy
• bed rest
• hydration
• pain/fever relievers

• Timely vaccination with 2 doses of MMR/MMV
• isolation
• surveillance
• awareness and education

Transmissable Spongiform Encephaopathies

• prions,
• infectious proteins(prp) induce normal proteins to fold improperly

• resistant to inactivation by heating, radiation or denaturing agents
• Host range do not appear to be species-specific

• also known as bovine spongiform encephalopathy (BSE)
• US FDA established enhanced feed ban which reduced the risk of tissue of infected cattle most likely to transmit BSE from entering into animal feed or human food

• outbreak in New Guinea
• 8x more common in wemen because they were more likely to participate in ritual mortuary cannibalism

1-15 yrs

direct contact, blood and nervous tissue

• headache
• minor loss of coordination
• inability to stand or walk
• inability to swallow

• incubate about 40 yrs
• primarily effect older idevidual due to its long incubation
• illness lasts about 4-5 mos

• progressive dementia
• impaired muscular coordination
• impaired vision
• involintary muscle spasms
• inability to move or talk
• coma

varian Creutzfeldt-Jacob Disease

• 2-4 yrs
• primarily affects younger indeviduals (29 yo)
• mean duration of illness is 14 mos

• psychiatric and behavorial issues
• unusual sensory symptoms
• progressive dimentia
• loss of movement and ability to talk
• come

•  no cure- disease is lethal
• supportive therapy

•  normal disinfection process does not render meat sterile
• surveillance
• eradication