Download College of Medicine Microbiology

College of Medicine
Microbiology
Mumps virus :
Dr. Jawad K. ALkhafaji
--------------------------------------------------------------------------------Important Properties:
 It belongs to paramyxoviruses.
 ssRNA genome.
 Helical nucleocapsid.
 Enveloped.
 It has spikes: three types of antigens H(for attachment), N(for release)
and F(fusion antigen for entry of virus).
 It has one serotype
Source and transmission:
 Humans are natural host.
 Mumps virus is highly contagious. It is transmitted via respiratory
droplets, salivary secretion, or urine(viruria is common).
Pathogenesis:
 The virus infects epithelial cells of URT and then spreads through
blood to salivary glands , primarily parotid glands , testes, ovaries,
pancreas, kidney, and in some cases to CNS(meninges).
 Alternatively the virus may ascend from buccal mucosa up Stensen
duct to parotid glands.
C/F:
 Ip :18-20 days; it causes mumps characterized by swelling of parotid
gland either unilateral or bilateral, that painful. Parotitis occurs in less
than 50% of infection. Fever ,malaise, anorexia are associated with
the disease.
 2 complication; orchitis(testes inflammation) in adults males , if
bilateral of testes can result in sterility. Other complication is
meningitis.
 It is common disease in school-age children. Most cases occur in
winter. 30% of children have sub-clinical infection.
 Lifelong immunity occurs in infected persons.
 Maternal Abs pass the placenta and provides protection during first 6
months of life.
Dx:
 Detection of S(soluble)-antigen(NP)by CFT indicate current infection.
 Detection of V(viral)-antigen indicates past infection. Also skin test
can be used to detect previous infection.
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Control:
 No specific antiviral therapy.
 MMR-vaccine(combined: mumps, measles and rubella) is given for
children at 15 months , it provide 10 years protection.
Measles virus:
 It belongs to paramyxoviruses.
 ssRNA genome.
 Shape of virus is spherical and helical symmetry.
 Enveloped.
 It has spikes: two types of antigens H and F.
 It has single serotype.
Source and transmission
 Humans are natural host.
 It is transmitted by inhalation of respiratory droplets during coughing.
 It is high communicable with 90% infection rate.
Path.
 The virus initially infects epithelial cells of trachea and bronchi of
respiratory tract and then spread and multiplies in LNs.
 The virus then enters blood (viremia) and disseminated to distant sites
throughout the body , including skin and mucosa.
 Maculopapular rash is due to cell-mediated immunity attack by
cytotoxic T-cells on measles-infected vascular endothelial cells in
skin.
 Antibodies may play role in vasculitis.
 General temporary suppression of cell-mediated immunity associated
with measles is consequence of infection of T and B cells, which
results in depressed IR and is major cause of secondary infections
responsible for morbidity and mortality.
 Formation of multi-nucleated giant cells, resulting from fusion of
infected cells with neighboring uninfected cells(due to F-protien), is
characterized pathogenic feature of measles infection.
 The virus evades neutralizing Abs by H-antigen or it spreads directly
cell to cell by F-protein. It also evade immune recognition by it ability
to induce temporary general immuno-suppression.
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C/F
 IP(10-14 days), It causes measles, prodromal phase of disease
characterized with fever, runny nose, cough, coryza, and
conjunctivitis(photophobia).
 After few days, 2-3 , Small white spots on inflamed buccal mucosa
membrane (koplike spots) appear inside cheek, followed by
maculopapular rash appearing first on head, and spreading to trunk.
 Most cases occur in children.
 Complication particularly in mal-nutrition children and immunocompromised patients: like otitis media, pneumonia, deafness and
encephalitis. In pregnant women may lead to stillbirth.
 One infection confers lifelong immunity.
Dx:
 Serological tests like ELISA.
 Genetic technique like PCR.
Control:
 Non-specific therapy, but sensitive to ribavirin.
 MMR vaccine is given to children at 15 months of age.
Rubella virus:
 It belongs to Togaviridae.
 ssRNA
 Icosahedral
 Enveloped.
 H-protein.
 One serotype.
Source and transmission:
 Humans are natural host.
 The virus is transmitted by respiratory droplets.
 It also transmitted from infected mother to her fetus via placenta.
Path:
 The virus infects and replicates in nasopharynx and then spreads to
local LNs, and cause lymphadenopathy.
 The virus then disseminated via blood to internal organs(spleen,
kidney, joints) and skin.
 In congenital , virus infects placenta and spread to fetus with multiple
organs involvement.
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 The rash is may result from Ab-Ag reaction that mediate vasculitis.
C/F:
 Ip(14-20 days), It causes Germany measles ,it is mild illness in
children and adults.
 The disease is characterized by maculopapular rash on face and
progresses on trunk, low fever , and lymphadenopathy.
 Complications; polyarithritis in adults with postnatal rubella that
caused by immune complex , while in pregnant (prenatal) especially
who infected during first trimester cause congenital rubella which is
characterized by malformation, cataract, deafness, cardiac
abnormalities and mental retardation.
 The infection confers lifelong immunity. Secondary infection of
rubella does not occur.
 Epidemics occur every 6-9 years.
Dx:
 Detection of specific Abs by serologic tests. Detection of IgM in
serum of pregnant or infant indicates recent infection.
Control:
 No antiviral therapy.
 MMR vaccine is given to children at 15 months of age. The vaccine
should not given for pregnant or immunocomromised individuals.
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