Viral Diseases
DNA Viruses
SS, nonenveloped, 1825 nm
Parvoviridae
Human parvovirus
B19
DS nonenveloped 7090 nm
40-57 nm
Adenoviridae
Mastadenovirus
Papovaviridae
Papillomavirus (HPV16)
Warts, some sexually transmitted. HPV-16 associated
with close to 90% of cervical cancers, especially serious
in South Carolina.
DS enveloped
200-350 nm
Poxviridae
Polyomavirus
Variola major
Polyoma and simian viruses cause tumors in animals.
Smallpox (pox – vesicopustular skin eruptions)
150-200 nm
Herpesviridae
Vaccina
Simplexvirus (Herpes
simplex 1 and 2;
Human herpes virus,
HHV-1 and HHV-2)
Cowpox
HSV 1 – usually oral transmission, lesions on upper
body (cold sores); HSV 2 – usually transmitted genitally,
infections of lower body. Lesions appear as sores after
cell lysis. Virus persists in latent state and is fairly easily
reactivated (UV exposure, fever, radiation, stress).
Primary infection is chicken pox, may be accompanied
by pneumonia and encephalitis in immuno-compromised
children; more severe in adults, usually accompanied by
pneumonia. Shingles (zoster) - virus remains dormant
in dorsal root or cranial nerve ganglia, reactivated by
stress, travels down nerve fiber and causes painful
blisters in the relevant dermatome. Unexposed people
can contract chicken pox from zoster lesions but not
vice versa; primary exposure imparts immunity to
exogenous infection.
Varicella zoster (HHV3)
Lymphocryptovirus
(HHV-4; Epstein-Barr)
Cytomegalovirus
(HHV-5)
Roseolovirus (HHV-6)
HHV-7
HHV-8
42 nm
Hepadnaviridae
Hepadnavirus
(Hepatitis B virus)
Erythema infectiosum, fifth disease (from a 1905 list of
skin rash diseases: 1. measles 2. scarlet fever 3. rubella
4. Filatow-Dukes disease 5. erythema infectiosum 6.
Roseola infantum) Mild flu-like symptoms, facial rash,
maculopapular rash on trunk and limbs.
Respiratory infections in humans, some cause tumors in
animals.
Infectious mononucleosis – malaise and lethargy,
pharyngitis, lymph node enlargement, spleenomegaly,
fever. Infects B cells and is associated with Burkitt’s
lymphoma (lymphoma of head and neck) and
nasopharyngeal carcinoma.
Usually inapparent, chronic, latent. Estimated 80% of
the population carries the virus. Disease appears
usually when host is immunocompromised and severity
of disease correlates with severity of
immunosuppression. Symptoms include pneumonia,
hepatitis, mononucleosis, and arthritis. Risk of graft
rejection increases significantly with CMV infection.
Roseola infantum (sixth disease, exanthem subitum)
High fever, generalized rash, rapid and complete
recovery
Infects most infants, causes measleslike rashes
Causes Kaposi’s sarcoma (seen in
immunocompromised individuals, primarily AIDS
patients)
Serum hepatitis – hepatitis B, may cause hepatocellular
carcinoma
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RNA Viruses
Genome
SS RNA, +
strand
Nonenveloped
28-30 nm
Family
Picornaviridae
35-40 nm
Calciviridae
SS RNA,
+ strand
enveloped 6070 nm
Togaviridae
40-50 nm
Flaviviridae
Virus
Poliovirus
Coxsackie B
virus
Hepatitis A
virus
Rhinovirus
Norovirus
Hepatitis E
virus
Alphavirus
Rubivirus
(rubella)
Flavivirus (an
arbovirus;
transmitted by
mosquito bites)
Hepatitis C
virus
Coronavirus
Nidovirales
80-160 nm
Mononegavirales
SS RNA
- strand
enveloped
70-180 nm
Coronaviridae
Rhabdoviridae
Lyssavirus
(rabiesvirus)
80-14,000 nm
Filioviridae
Filovirus
(Marburg virus,
Ebola virus)
150-300 nm
Paramyxoviridae
Mumps virus
Measles virus
RNA – strand,
1 strand
32 nm
Deltaviridae
Hepatitis D
90-120 nm
Bunyaviridae
110-130 nm
Arenaviridae
Bunyavirus
Hantaviruis
Arenavirus
Disease
Polio; loss of anterior horn cells (motor neurons), flaccid
paralysis, sometimes of diaphragm  iron lung
Post-viral fatigue syndrome (PVFS), chronic fatigue syndrome
Acute hepatitis, 90% recovery, fecal-oral inoculation
Common cold
Gastroenteritis
Enterically transmitted non-A, non-B hepatitis
Transmitted by arthropods, eastern and western equine
encephalitis.
German measles; respiratory transmission, causes rash,
imparts long-lasting immunity. Especially dangerous to 1st
trimester fetuses.
Yellow Fever: a classic viral hemorrhagic fever. Hepatic
necrosis, jaundice, fever, vomiting, diarrhea, mortality rate of
80%; Yellow fever prohibited significant colonization of large
parts of South and Central America until controlled (elimination
of mosquito population); Panama canal was discontinued until
the disease was controlled. Vaccine is now available.
Blood-borne non-A non-B hepatitis
Upper respiratory infections, common cold.
Rabies: Zoonotic, transmission by contact with infected animals.
Virus spreads from wound to brain along neurons. Incubation is
1 week to 1 year depending on site of wound. Symptoms
include cerebral hyperirritability, rage, pharyngeal muscle
spasm, alternating mania and coma until death, usually by
respiratory failure (destruction of respiratory center. Vaccine
available, treatment includes injection with immune globulin and
vaccine.
Viral hemorrhagic fever, both initiate from contact with infected
monkeys or tissues, may be passed secondarily by contact with
secretions or unsterilized instruments. Human-human contact
inefficient. Acute fever, muscle pain, abdominal pain, rash,
severe gastrointestinal bleeding, generalized hemorrhage,
shock, death. Ebola has a mortality rate of close to 90%.
Mumps. Half of infections are unapparent. Invades upper
respiratory tract and lymph nodes, spreads to target organs
(most common is parotid gland). Can cause orchitis (testicular
inflammation) in post-pubescent males, may result in sterility.
Vaccine available.
Red measles. Transmission by inhalation usually, spreads to
lymph nodes, infects T-cells. Antibody titer rises, rash appears
(probably immune complex mediated hypersensitivity), fever,
cough, conjunctivitis. Recovery is usually rapid, complete, and
imparts lifelong immunity.
Depends on co-infection with Hepatitis B virus –formerly known
as the delta agent and thought to be a defective virus the
disease is actually caused by a viroid enclosed in a hepatitis B
viral coat
Hantaviruses, cause viral hemorrhagic fevers
Venezuelan hemorrhagic fever, Lassa fever
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RNA – strand,
multiple
strands
segmented
80-200 nm
DS RNA +
strands
DS RNA nonenveloped 6080 nm
Orthomyxoviridae
Influenza
viruses
Retroviridae
Oncoviruses:
HTLV I & II
Lentivirus (HIV)
Reoviridae
Reovirus
Rotavirus
Influenza: Types A, B, and C. Segmented genome allows
extensive recombination leading to antigenic changes.
Transmitted by inhalation, infects respiratory mucosa, allows
secondary bacterial infections to occur after epithelial
denudation.
Leukemia
AIDS
Respiratory infections
Gastroenteritis
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