RNA Viruses

Influenza transmission

Respiratory droplets, infects humans and mammals, causes influenza and pneumonia with risk of bacterial superinfection

Influenza clinical signs

Fever, myalgia, sore throat, cough, primary viral pneumonia, complications like otitis media and croup in children

Antigenic drift

Minor point mutations in influenza A & B causing seasonal outbreaks every 1–3 years

Antigenic shift

Major genetic reassortment in influenza A only, causing pandemics every ~10 years

Orthomyxoviruses

Influenza A and B, diagnosed from respiratory specimens using PCR or culture

Paramyxoviruses

Measles, mumps, RSV, parainfluenza, detected from respiratory specimens by PCR or FA stain

Reoviruses

Rotavirus, detected from stool by EIA or latex agglutination

Picornaviruses

Polio, coxsackie, echo, HAV, rhinovirus—detected by culture, PCR, or serology (HAV)

Arboviruses defintion

Mosquito-borne viruses like WNV, dengue, equine encephalitis

Flaviviruses

WNV, dengue, HCV

Togaviruses

Rubella and equine encephalitis viruses

Bunyaviruses

California encephalitis, La Crosse, hantavirus

Rubella structure

ssRNA, icosahedral capsid, enveloped virion in Togaviridae

Coronavirus structure

ssRNA, enveloped virus seen by EM with crown-like appearance

Rotavirus structure

dsRNA, segmented, icosahedral, non-enveloped Reoviridae virus

Norovirus structure

ssRNA, non-enveloped Calicivirus detected by PCR or EM

Picornavirus structure

ssRNA, icosahedral, non-enveloped small RNA virus

RSV structure

ssRNA, helical, enveloped Paramyxovirus causing syncytia

Measles structure

ssRNA, enveloped Paramyxovirus with helical nucleocapsid

Influenza A structure

ssRNA, segmented, helical, enveloped Orthomyxovirus

Hantavirus structure

ssRNA, enveloped Bunyavirus transmitted by rodents

Poliovirus structure

ssRNA, icosahedral, non-enveloped enterovirus

Arbovirus transmission

Mosquito vector with vertebrate host, causing fever, meningitis, or encephalitis

Rubella transmission

Respiratory spread causing mild rash illness or congenital rubella

Rotavirus transmission

Fecal-oral spread, winter seasonality, nosocomial infection common

Enterovirus transmission

Fecal-oral spread, peaks in summer and fall

Rhinovirus transmission

Contact with respiratory secretions, 102 serotypes cause common cold

Hepatitis A transmission

Fecal-oral transmission, no chronic infection, outbreaks common

Hepatitis C transmission

Bloodborne spread via needlesticks, sharps, or IV drug use

West Nile Virus transmission

Mosquito vector, birds as reservoir hosts, causes fever or neuroinvasive disease

Rubella clinical features

Mild rash, lymphadenopathy, danger to fetus in congenital infection

Enterovirus clinical features

Polio, HFMD, herpangina, myocarditis, aseptic meningitis

RSV clinical features

Bronchiolitis and pneumonia in infants, URI in adults

Coxsackievirus A clinical features

Hand-foot-mouth disease with oral ulcers and vesicular rash

Measles clinical features

Fever, cough, coryza, conjunctivitis, Koplik spots, red rash, complications include pneumonia and SSPE

Rotavirus clinical features

Severe watery diarrhea and vomiting in infants and young children

Rubella prevention

MMR live attenuated vaccine

RSV prevention

Infant vaccine available and infection control isolation/cohorting

Influenza prevention

Annual influenza vaccine

Measles prevention

MMR vaccine prevents infection

Rotavirus prevention

Oral rotavirus vaccine in infancy

Enveloped RNA viruses

Influenza, RSV, measles, mumps, parainfluenza, coronaviruses, flaviviruses, togaviruses, bunyaviruses

Nonenveloped RNA viruses

Picornaviruses, reoviruses, noroviruses (Calicivirus)

RNA virus diagnostics

PCR, antigen detection, serology, EM, and cell culture depending on virus

Cytopathic effect

Visible cellular changes from viral infection such as rounding, lysis, syncytia, or inclusion bodies