Viruses Flashcards
Influenza virus (A/B/C)
Family: Orthomyxovirus (ss enveloped negative RNA)
2 Glycoprotein spikes: Hemagglutinin (H1, H2, H3) and Neuraminidase (N1, N2)
Host: humans
Incubation: 2 days
Transmission: Direct droplet spread
Entry point: Upper respiratory tract
Symptoms: abrupt onset, fever, malaise, headache, chills FACTS
Complications: Pneumonia, Bacterial superinfection, Reye’s syndrome
Diagnostic: nose and through swabs for cell culture or Rapid Flu (tests for antigen), serodiagnosis.
Prevention: Antivirals, Vaccines (killed and live attenuated)
Coronavirus
Family :Picornavirus (ss naked, + stranded RNA)/coronavirus Host: human Entry point: upper respiratory tract Transmission: respiratory droplet Incubation: 2-4 days Symptoms: Sneezing, nasal discharge, cough headache, sore throat Duration: 1 week Diagnostics: none Prevention: None
Rubella (German Measles)
Family: Togavirus (ss enveloped positive RNA)
Host: humans
Transmission: respiratory droplets, transplacental
serotype: 1
Entry Point: URT
Incubation: 14-21 days
Symptoms: low grade fever, lymphadenopathy, w/in 24 hrs macular rash and petechial rash on soft palate
Duration: 1-3 days
Complications: Arthritis, Enchepalitis, *fetal damage (heart disease, deafness, blindness)
Diagnostics: Viral culture, RT-PCR, Serology
Prevention: Live vaccine (MMR)
Flavivirus
ssRNA
enveloped capsid
Hepatitis C, west nile virus
Measles (Rubeola)
Family: Paramyxovirus (ss enveloped negative RNA)
Morbillivirus (infectious agent)
Serotype: 1
Host: humans
Transmission: person to person contact, respiratory droplet
Entry Point: Upper respiratory tract
Incubation: 7-18 days
Symptoms: fever, cough, coryza, conjunctivitis. Then Koplik spots (inside of cheek). Then rash to the head, trunk, then extremities
Complications: Pneumonia, enchephalitis, bleeding disorders, bacterial superinfection
Diagnostics: Viral culture, RT-PCR, serology
Prevention: Live vaccine, immune serum globulin
Rabies Encephalitis
Family: Rhabidovirus (ss negative enveloped RNA)
Transmission: usually a dog bite (infected secretions)
Host: all mammals
Entry Point: multiples in muscle cells, then travels to CNS then replicates to brain cells
Incubation: 10 days - 1 year
Symptoms: affects the CNS, foaming of the mouth, seizures, hallucinations. survival after being symptomatic is 4 days
Diagnostics: RT-PCR, serology
Prevention: pre exposure- inactivated vaccine, post exposure- human hyperimmune anti rabies globulin plus rabies vaccine
HIV
Family: Retrovirus (ss postive enveloped RNA)
LATENT
3 essential enzymes for replication: reverse transcriptase, Protease, integrates.
2 viral glycoproteins: gp120 and gp41
Transmission: requires intimate contact with infecting source, perinatal
Symptoms: acute (fever, malaise, maculopapular rash, highly contagious), latent (asymptomatic but contagious), AIDS (decline in CD4 cells, immunocompromised)
Diagnostics: ELISA, HIV antigen test, HIV RNA viral load assay
Prevention: appropriate screening, avoid exposure, antiretrovirals, pre and post exposure prophylaxis.
Rotavirus
Family: Reovirus (ds naked DNA) Host: humans and animals Transmission: fecal oral, cooler months Serotypes: 5 Incubation: 1-3 days, Symptoms: vomiting then hours later watery brown stools Complications: dehydration Diagnostics: ELISA, PCR, serology Prevention: live oral vaccine good hygiene
Norwalk virus
Family: Calcivirus (ss Naked, positive RNA)
Infectious agent: Norovirus
Transmission: fecal oral, consumption of contaminated food or water or uncooked shellfish
Serotypes: 4
Incubation: 10-51 hours
Symptoms: abrupt onset of vomiting and diarrhea (usually at the same time)
Complication: dehydration
Diagnostics: RT-PCR, enzyme immunoassay
Prevention: hygiene
Hepatitis E
Family: Hepevirus (ss, positive, naked RNA)
Transmission: fecal oral
Host: humans
Incubation: 40 days
Symptoms: Jaundice, anorexia, nausea, fever, hepatomegaly, vomiting
Complications: when symptomatic it can fatal (especially when pregnant)
Diagnostics: Serology
Prevention: None
Varicella Zoster-chicken pox
Herpesvirus (ds enveloped DNA)
LATENT INFECTIONS
Host: Humans
Transmission: respiratory droplet and skin contact with lesion
Serotype: 1
Entry point: Upper respiratory tract
Incubation: 14-21 days
Symptoms: Prodromes- fever, malaise, papulovesicular rash in crops on trunk then goes to head and extremities (may see 3 different stages of the rash)
Complications: Varicella Pneumonia, enchephilits, Reye’s syndrome
Diagnostics: Tzanck smear, Viral culture, PCR, serology, direct fluorescent antibody
Prevention: Antivirals (Acyclovir), Live Vaccines, Varicella zoster immune globulin
Poxvirus
dsDNA
Enveloped capsid
Smallpox, Molluscum contagiosum
Adenovirus
dsDNA
Naked
Respiratory diseases, Gastroenteritis
Fifth Disease
Family: Parvovirus B19 (ss DNA naked)
Host: humans
Transmission: respiratory, blood products, direct contact or fomites, vertical
Incubation 4-12 days
Symptoms: Fever, malaise, pruritus, “slap cheek rash”, 1-2 days later rash on arms and legs
Duration: 1-2 weeks
Complications: high risk to fetus, nephritis, encephalitis, hepatitis, thrombocytopenia
Diagnostics: NAAT, serology
Prevention: immunoglobin, NO VACCINE
Viral Pharyngitis
Family: Multiple (enveloped and naked)
Host: Humans
Entry point: upper respiratory
Transmission: droplet, direct contact, fomites
Symptoms: Sore throat, headache, malaise, hoarseness, ear pain, cough
Diagnostics: RADT, throat culture
Prevention: hand washing/ good hygiene
MAIN THING IS RULE OUT BACTERIAL INFECTION
Varicella Zoster-Shingles
Herpesvirus (ds enveloped DNA)
LATENT INFECTION
Transmission: respiratory droplet and skin contact with lesion
Entry point: Upper respiratory tract
Symptoms: Painful vesicles along the course of a sensory nerve of the head or drunk (follows dermatome)
Diagnostics: Tzanck smear, Viral culture, PCR, serology, direct fluorescent antibody
Prevention: Antivirals, Live Vaccines, Varicella zoster immune globulin
Complications: posteherpetic neuralgia, pneumonia
Roseola (Exanthem Subitum)
Family: Herpesvirus (ds enveloped DNA) Human herpesvirus 6 or 7 Transmission: saliva Symptoms: fever x 3 days, then faint maculopapular rash Diagnostics: serology and PCR Prevention:
Mumps Virus
Family: Paramyxovirus (ss enveloped negative RNA)
Host: human
Transmission: respiratory droplet or direct contact or fomites
Serotype: 1
Entry Point: upper respiratory tract
Incubation: 18-21 days
Symptoms: fever, malaise, anorexia, tender salivary gland
Duration: 1 week
Complications: orchitis is post pubertal males, meningitis
Diagnostics: viral culture, RT-PCR, serology
Prevention: Live vaccine (MMR)
Hepatitis A
Family: Picornavirus (ss positive naked RNA)
Transmission: fecal oral, contaminated food and water
Serotypes: 1
Host: humans and primates
Incubation: 15-45 days
Symptoms: RUQ pain, fever, anorexia, clay colored stools, hepatomegaly
Duration- days- weeks
Diagnostics: serology
Prevention: avoidance of exposure, active immunization, passive immunity
Hepatitis B
Family: Hepadenovirus (ds enveloped DNA
Transmission: Vertical, sexual contact, parentally
Serotypes: 4
Host: humans
Incubation: 10 weeks
Symptoms:RUQ pain, jaundice, grey colored stools, rash
Duration: several months
Complications: liver failure, fulminant hepatitis, chronic hepatitis, HCC
Diagnostics: serology
Prevention: recombinant vaccine, Hep B immune globulin, reverse transcriptase inhibitors
Hepatitis D (HDV)
Family: Deltavirus (ss Enveloped RNA)
Transmission: needs Hep B surface antigens. high risk for injunction drug users
Symptoms: looks like HBV or HAV
Complications: chronic cirrosis, progressive liver disease
Diagnostics: serology
Prevention: recombinant vaccine, Hep B immune globulin, reverse transcriptase inhibitors
Hepatitis C
Family: Flavivirus (ss positive enveloped RNA)
Transmission: parenterally, sexually transmitted
Host: humans
Incubations: 6-12 weeks
Symptoms: usually asymptomatic
Complications: cirrhosis, increased HCC risk
Diagnostics: ELISA, RIBA, RT-PCR
Prevention: no active and passive immunity, Antiviral medications
Enterovirus
Family: Picornavirus (naked ss positive RNA)
Transmission: fecal oral, infects GI and upper respiratory tract
Incubation: 2-10 days
Groups: Poliovirus (paralytic) , Coxsackievirus (Group A- hand foot mouth disease, Group B- myocarditis, pleurodynia), Echovirus (ascetic meningitis, URI)
Diagnostics: RT-PCR
Prevention: inactivated poliovirus vaccine
Arboviruses
Family: 1. Togavirus (ss positive enveloped RNA). 2. Flavivirus (ss positive enveloped RNA), 3. Bunyavirus (ss negative enveloped RNA)
Transmission: infected blood sucking insects
Symptoms: acute febrile illness, encephalitis, meningitis
Prevention: immunization for yellow fever, tick borne, japanese b enchapalitis.
