M. A. El- Farrash In the name of Allah, Most Gracious, Most Merciful
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M. A. El-Farrash
In the name of Allah, Most Gracious, Most Merciful
Virology of Pharyngitis, Gastroenteritis
and Meningitis
Prof. Mohamed El-Farrash2015
PharyngitisPharyngitis “not tonsillitis” is the most
common cause of a sore throat.
Like many types of inflammation, pharyngitis
can be Acute “characterized by a rapid onset
and typically a relatively short course”
or Chronic (relatively long course with milder
clinical form).
M. A. El-Farrash
Most (40–80%) acute cases of pharyngitis are
caused by viral infections.
The remainder (20 – 60 %) are caused by
bacterial infections, fungal infections, or
irritants as pollutants or chemical substances.
Acute Pharyngitis
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Viral and Bacterial Pharyngitis
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Viral PharyngitisPharyngitis can be a feature of many different
types of viral infections.
Adenovirus is the most common of the viral
causes.
In Adenoviral pharyngitis the degree of
neck lymphadenitis is modest and the throat
often does not appear red, although it is very
painful. M. A. El-Farrash
Adenoviruses Morphology
M. A. El-Farrash
Icosahedral,
non-enveloped
virus containing
double stranded
linear DNA genome.
Human adenoviruses are classified into 6
subgroups (A – F) containing 56 serotypes.
Adenoviruses Pathogenesis
Infections by adenoviruses are very common.
Most infections are asymptomatic.
Virus was isolated from tonsils/adenoids
surgically removed, indicating latent infections.
It is transmitted by droplet, contact or feco-oral.
Adenovirus infections are difficult to distinguish
from Influenza, Parainfluenza or RSV. M. A. El-Farrash
Adenoviruses can cause:
1. Acute febrile pharyngitis and pneumonia
2. Conjunctivitis and keratoconjuctivitis
3. pharyngo-conjunctival fever
4. Gastroenteritis and intussusceptions in infants
5. Acute hemorrhagic cystitis
6. Sever pneumonia in AIDS patients.
M. A. El-Farrash
Adenoviruses Pathogenesis
Diagnosis and Treatment
Laboratory diagnosis is done by:
1. Virus isolation by culture on human fibroblasts
and founding the CPE (rounding, clustering and
swelling)
2. PCR for DNA detection
3. Antibody detection by CF, NT and HI tests.
Management: No specific antiviral agents and
no vaccine. M. A. El-Farrash
Herpesviruses
Eight human herpes virus species are known.
All have the ability to enter a latent state
following primary infection and to be reactivated
at a later time.
Structure:
Capsid: Icosahedral.
Genome: Double stranded, linear DNA.
Envelope: With glycoprotein spikes.
Human Herpes Viruses
M. A. El-Farrash
1- Alpha herpesvirinae:
Human herpesvirus 1, 2 (HSV-1, HSV-2)
Varicellovirus (HHV-3 or VZV).
2- Beta herpesvirinae:
Cytomegalovirus (CMV),
Roseolovirus (HHV-6, HHV-7).
3- Gamma herpesvirinae:
Epstien-Barr virus (EBV),
Kaposi sarcoma associated virus (HHV-8).
Herpes viruses Classification
M. A. El-Farrash
The Epstein-Barr virus (EBV) or Human herpes
virus 4 (HHV-4) is one of the most common
viruses in humans (more than 70%
seropositivity).
EBV has a dual cell tropism for human B-
lymphocytes and epithelial cells.
EBV often causes asymptomatic infection but
may cause infectious mononucleosis in few cases.
Epstein-Barr virus (EBV)
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Also known as glandular fever, or Mono.
Transmission occurs from exchanging saliva
(Kissing disease) and also by airborne infection.
It is associated with the appearance of unusually
large lymphocytes (atypical lymphocytes) in
blood.
Symptoms are fever, general malaise, sore throat
and generalized lymphadenitis.
Infectious Mononucleosis
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Burkitt's lymphoma is a type of Non-Hodgkin's
lymphoma most common in equatorial Africa
and co-exists with the presence of malaria.
Malaria infection causes reduced immune
surveillance of EBV immortalized B cells, so
allowing their proliferation.
Burkitt's lymphoma commonly affects the jaw
bone, forming a huge tumor mass.
EBV-associated malignancies
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Burkitt's lymphoma
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It is found predominantly in Southern China
and Africa, due to genetic and environmental
factors.
It is more common in people of Chinese ancestry
(genetic), and is also linked to Chinese diet (high
amount of smoked fish, which contain
nitrosamines) a well known carcinogens.
Nasopharyngeal carcinoma
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Nasopharyngeal carcinoma
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1. Blood film: lymphocytosis and many abnormal
lymphocytes.
2. Detection of EBV in lymphocytes by PCR.
3. Paul-Bunnel test: It is non specific test in which
we add serum of the patient + sheep RBCs
agglutination of RBCs (positive).
4. Detection of specific antibodies to viral antigens.
5. Virus isolation from saliva.
EBV Laboratory Diagnosis
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Myxoviruses
Name is from the Greek 'myxo' = mucus.
The first isolated and known member of the
group was Influenza virus.
The group has 2 families:
1. Orthomyxoviridae: which contains the influenza
viruses and other non human viruses.
2. Paramyxoviridae: containing the parainfluenza,
mumps, measles and respiratory syncytium
virus.
Myxoviruses
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Orthomyxoviridae: Particle size: 80-120 nm (highly pleomorphic)
Core diameter: 9 nm.
Genome: Segmented (-) sense RNA.
Replication: Nuclear.
Paramyxoviridae: Particle size: 125-250 nm (somewhat pleomorphic)
Core diameter: 14-20 nm.
Genome: Non-segmented (-) sense RNA.
Replication: Cytoplasmic.
Myxoviruses
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Influenza VirusInfluenza virus belongs to Orthomyxoviridae
family (s/s, negative-sense RNA viruses).
The particles are mostly spherical.
The virus has a lipid envelope from which project
prominent glycoprotein spikes of two types:
1. Haemagglutinin (HA or H),
2. Neuraminidase (NA or N).
The genome is composed of 8 segments (7 in type B). M. A. El-Farrash
Influenza Virus
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Virus MutationEvery now and then (10 - 15 years) a major new
pandemic strain appears in man, with a totally
new H and sometimes a new N as well (Antigenic
Shift).
This new variant may cause a major epidemic
around the world.
Over the subsequent years this strain undergoes
minor changes (Antigenic Drift) every two to
three years. M. A. El-Farrash
Serotypes
There are 16 known (H) serotypes and 9 known
(N) types of Influenza A virus giving a large
number of subtypes due to different associations.
Fifteen subtypes of influenza A virus are known
to infect birds, thus providing a reservoir of
influenza viruses circulating in bird populations.
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Types and Host range
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Influenza is characterized by fever, myalgia, headache and pharyngitis. There is usually no coryza (runny nose) which characterizes common cold infections. Symptoms may be very mild, (even asymptomatic) moderate or very severe.Spread: rapid via aerial droplets with inhalation into the pharynx or lower respiratory tract. Incubation: short: 1-3 days. Rapid spread leads to epidemics.
Influenza
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Laboratory DiagnosisA. Viral Isolation :
Samples: Respiratory secretions: obtained by
direct aspirate, gargle or nasal washings.
Rapid examination of cells by IF then
inoculation on cell cultures (or egg embryo).
PCR and genotyping or serotyping.
B. Serology :Detection of antibodies in the serum by HAI.
M. A. El-Farrash
Amantadine and Rimantadine are active against
influenza A viruses (but not B).
Recently, they became not effective against
seasonal strains.
Tamiflu: is an inhibitor of neuraminidase taken
in pill form which causes decreased severity and
duration of symptoms.
M. A. El-Farrash
Treatment of Influenza
Vaccines are produced by re-assortment of egg-adapted strains with strains having the season HA type.
Large amounts of virus are then grown in embryonated eggs (cheap and efficient), purified and formalin inactivated.
The vaccine is given sub-cutaneously.
For new antigenic type, 2 doses are necessary for adequate protection (which depends on age of patient).
M. A. El-Farrash
Influenza vaccines
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Diarrhea VirusesDiarrhoa is not as dramatic
illness as AIDS.
However, the viruses
causing diarrhea are of
great economic importance.
Diarrhea viruses include : Astroviruses,
Adenoviruses, Reoviruses and Caliciviruses.
ReovirusesRespiratory Enteric Orphan viruses, i.e. viruses
that infect the human respiratory and intestinal
tracts, without causing a known disease.
There are more than 150 species in the family
Reoviridae. The most important one is Rotavirus.
They are unified by their most unique feature;
the composition of their genome d/s RNA.
M. A. El-Farrash
RotavirusesRotaviruses have three shells: an outer capsid,
inner capsid and core which surrounds the 11
segments of double-stranded RNA.
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Infections cause endemic/epidemic gastroenteritis
and infantile diarrhea (a major cause of death in
the developing world).
Rotaviruses cause generally self-limited
infections rare in adults and trivial in
consequence, but may kill infants unless properly
treated (oral rehydration keeps children alive).
Rotaviruses
Rotaviruses are the most common cause of severe
diarrhea worldwide.
In developing countries, rotavirus infection may
cause up to one million deaths each year,
accounting for an estimated 20-25% of all deaths
due to diarrhea and 6% of all deaths among
children less than five years old.
Rotaviruses
M. A. El-Farrash
Infection occurs by feco-oral route.
Diagnosis is confirmed by virus detection in stool
by E/M or isolation by culture.
Treatment : oral rehydration therapy with
isotonic glucose/mineral salt solution.
Diagnosis and Management
M. A. El-Farrash
Astroviruses
M. A. El-Farrash
Astroviruses are 28–35 nm, icosahedral viruses
that have a characteristic five- or six pointed
star-like surface structure when viewed by
electron microscopy.
Astrovirus has a non-segmented, single stranded,
positive sense RNA genome within a non-
enveloped icosahedral capsid.
They have been shown to be an important cause
of gastroenteritis in young children worldwide.
Norwalk Virus
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Norovirus is a genus of single-stranded RNA,
non-enveloped viruses in the Caliciviridae family.
The known viruses in the genus are all
considered a single species called Norwalk virus.
Noroviruses are the most common cause of
viral gastroenteritis in humans, and affect people
of all ages.
Norwalk “Norovirus”
The viruses are transmitted by contaminated
food or water; by person-to-person contact; and
via aerosolization of the virus and subsequent
contamination of surfaces.
The virus causes over 200,000 deaths each year;
these deaths are usually in less developed
countries and in the very young, elderly and
immunosuppressed.
Norwalk “Norovirus”
Norovirus infection is characterized by nausea,
forceful vomiting, watery diarrhea, and
abdominal pain, and in some cases, loss of taste.
General lethargy, weakness, muscle aches,
headache, coughs, and low-grade fever may
occur.
The disease is usually self-limiting, and severe
illness is rare.
Norwalk “Norovirus”
Viral Meningitis
Viral Meningitis
Viral meningitis is sometimes referred to as
"aseptic meningitis" in contrast to meningitis
caused by bacteria.
Viral meningitis is most commonly caused
by enteroviruses, however, only a small
number of people with enterovirus infections
actually develop meningitis.
Causative organisms include:1. Enteroviruses
i. Echovirus
ii. Poliovirus (PV1, PV2, PV3)
iii. Coxsackie A virus .
Other viral infections that can lead to meningitis include
2. Herpesviruses,
3. Arboviruses
Viral Meningitis
5. LCMV (lymphocytic choriomeningitis
virus), which is spread by rodents,
6. Human Immunodeficiency Virus (HIV)
7. Measles
8. Mumps
9. St. Louis Encephalitis virus
10.West Nile virus
Viral Meningitis
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