Micro
Measles
Enveloped, ss negative-sense
RNA virus (Paramyxovirus family)
Mumps
Enveloped, ss negativesense RNA virus
(Paramyxovirus family)
Resp droplet, saliva
Inact by dessication
Rubella
Enveloped, ss-positive
sense RNA virus
(Togavirus family)
Resp droplet
Dengue
Enveloped, ss positivesense RNA virus
(Flavivirus family)
An arbovirus with a
mosquito vector;
monkeys are the
reservoir
one
-Infects epithelial cells of
the respiratory tract,
spread to local lymph
nodes and systemic
viremia
-Congenital infection
leading to severe
teratogenic effects can
occur in non-immune
pregnant mothers
-Antibody can stop
viremic spread of virus,
but cell-mediated
immunity eliminates
virus
-Disease is usually
benign in children who
after a 14-21 day
incubation period have a
3-day maculopapular
rash with fever, malaise
and swollen glands
-Adult infection is more
severe and can lead to
arthralgia, arthritis and
post-infectious
encephalitis
-Congenital infections
characterized by
cataracts, mental
retardation, deafness
and frequently death
within one year if
infection occurs during
first twenty weeks of
pregnancy
~20% of childbearing
women escape
childhood infection and
are susceptible unless
vaccinated
four
-Virus replicates in
monocytes and vascular
endothelium
-Antibody from previous
infection can increase
efficiency of infection by
different serotype
-Enhancing antibody
effect due to Fc portion of
antibody (Figure 1)
-Sometimes a clinical
diagnosis, but ELISA for
IgM done for active
infection
-ELISA for IgG early in
pregnancy to determine
immune status of
pregnant women
Clinical
No antivirals
replacement of fluids,
Transmission
Resp droplet
Inact by dessication
Serotypes
Pathogenesis
One
-Infects epithelial cells of
respiratory tract, spreads to
lymphatic system and then by
cell-associated viremia
-Maculopapular rash due to T cell
response to viral infection of
endothelial cells in small vessels
-Cell-mediated immunity needed
to stop infection due to cell-cell
virus spread
-During clinical disease and for
several weeks after, causes
temporary immunosuppression
due to lymphocyte infection
One
-Infects epithelial cells of
respiratory tract and
spreads systemically in
lymphocytes and
monocytes and by viremia
-Infects parotid glands via
Stensen's duct or viremia
(parotitis in 30-40% of
infections)
-Cell-mediated immunity
needed to stop
progression of infection
Clinical Disease
-A childhood infection whose
prodromal period is characterized
by a high fever and the three “C’s”
– cough, coryza and conjunctivitis
with some photophobia
-Koplik's spots appear on buccal
mucosa about 12-24 hours before
a maculopapular rash first seen
below the ears
-Complications include a postinfectious encephalitis, giant-cell
pneumonia, atypical measles, and
after many years, SSPE
-Sudden onset parotitis
and fever perhaps
accompanied by orchitis,
pancreatitis and
meningoencephalitis
-CNS involved in 50% of
those infected, but
symptoms in only 10%
Epidemiology
-95% of infected individuals who
are not immune will get the
disease
-Peak seasons in winter and
spring
-Immunocompromised
individuals suffer a more serious
outcome
Dx
Clinical
-Often asymptomatic
infections
-Late winter and early
spring disease; occurs in
crowded conditions, e.g.,
schools, ships
-More serious in IC’d pt
-Not a significant cause of
male sterility
Clinical diagnosis if
symptoms present
-Virus isolation from
saliva, CSF or urine
-ELISA of mumps-specific
IgM
Tx
No Antivirals
No antivirals
-Adults — fever/rash
syndrome with headache
and severe joint and
muscle pain
-Children — in endemic
areas dengue
hemorrhagic shock
syndrome with up to 10%
mortality
Endemic areas include SE
Asia, Pacific area, India
and the Caribbean
correction of electrolyte
balance and blood
transfusion if hemorrhaging
is severe
Prevention
Live attenuated vaccine
containing Enders virus
Live attenuated
vaccine (Jeryl Lynn
Strain)
Live attenuated, coldadapted RA 27/3
vaccine strain
No vaccine since it may
enhance possibility of
serious disease
VARICELLA ZOSTER VIRUS
•
Causes chickenpox, previously discussed in “Viral Infections of the Skin,” could also be considered with this grouping of viruses
Viruses - ARBOVIRUSES
•
Various Togaviruses, Flaviviruses and Bunyaviruses cause systemic infections with fever in endemic areas
•
Infections are usually subclinical or mild, but may be serious in some people
•
Diseases include 1) encephalitis (discussed in nervous system course), 2) hemorrhagic fevers, and 3) febrile illnesses with or without rashes
•
Colorado Tick Fever, a usually mild disease with fever, headache, myalgia, and rash, needs to be distinguished from Rocky Mountain
Spotted Fever, a rickettsial disease
Dengue Virus figure:
Figure 1: The pathogenesis of dengue hemorrhagic fever
shock syndrome. There are four serotypes of dengue
virus. Types 1 and 2 are illustrated as an example.
Antibody to type 1 binds to type 2 without preventing
infection with type 2.
Practice Q answer options
A. Measles virus
B. Mumps virus
C. Rubella virus
D. Dengue virus
E. All of the above
F. None of the above
Practice Questions:
1. Which are DNA viruses?
2. Which are positive sense single stranded viruses? Negative sense?
3. Which DON’T we vaccinate for? Why?
4. What would you expect to see histologically in a patient with Koplik’s spots & maculopapular rash?
5. Patient presents with parotitis, fever, and orchitis. What virus? What other complications should you monitor for? What family
does this virus belong to?
6. What antivirals are used to treat measles, mumps, and rubella?
7. ELISA for IgG early in pregnancy is used to detect the immune status for what virus? What are the potential teratogenic effects of
this virus?
8. 3 year-old child in India presents with dengue hemorrhagic shock syndrome. What is the mechanism of disease? How is this
treated?
Answers:
1. F, they are all RNA viruses
2. Positive = C, D; negative = A, B
3. D cuz enhancing antibody effect
4. Syncitial cell formations due to measle virus inducing cell-cell fusion
5. Mumps; pancreatitis & meningoencephalitis; paramyxovirus family
6. None! So get vaccinated to prevent disease
7. Rubella; cataracts, MR, deafness, early death
8. Enhancing antibody effect (see figure 1 above) Tx fluids, electrolyte balance, bld transfusion if severe hemorrhage.