Viral Diseases
Time Table for Clinical Virology
Week
1
2 &3
4
5
Topics
Parvoviridae
Herpesviridae
Papovaviridae
First Examination
Adenoviridae
6
7&8
Orthomyxoviridae
Paramyxoviridae
9
Retroviridae (HIV)
10
Coronaviridea + Rubella virus
11&12
13
14
15
Second Examination
Picornaviridae
Hepatitis viruses
Hepatitis viruses
Reoviridae
Final Exam
Evaluation and Grading
First Midterm Exam:
10
Second Midterm Exam:
10
Practical Exam:
15 + 5 attendance
Others
20
Final Exam:
40
Human Viral Diseases
Most of the clinically important viral pathogens can be
categorized into groups according to their structural
characteristics, i.e., DNA enveloped viruses, DNA non
enveloped viruses, RNA enveloped viruses, and RNA
non enveloped viruses
Major Viral Pathogens
Structure
Viruses
Single-Stranded DNA Genomes
Parvoviridae (Parvovirus B19)
Papovaviridae (Papillomavirus, Polyomavirus)
Double-Stranded DNA Genomes
Adenoviridae, Herpesviridae, Poxviridae,
Hepadnaviridae.
Picornaviridae, Caliciviridae, Togaviridae,
Single +ve Sense RNA Genomes
Coronaviridae Flaviviridae, Retroviridae.
Orthomyxoviridae, Bunyaviridae,
Single -ve Sense RNA Genomes
Arenaviridae, Paramyxoviridae,
Rhabdoviridae, Filoviridae.
Double-Stranded RNA Genomes
Reoviridae
Classification of DNA Viruses
Virus Family
Envelope
Capsid
Size (nm)
Structure
Medically Important Viruses
Parvovirus
No
Icosahedral
22
SS, linear
B19 virus
Papovavirus
No
Icosahedral
55
DS, circular,
supercoiled
Papillomavirus
Adenovirus
No
Icosahedral
75
DS, linear
Adenovirus
42
DS,
incomplete
circular
Hepatitis B virus
Hepadnavirus
Yes
Icosahedral
Herpesvirus
Yes
Icosahedral
100
DS, linear
Herpes simplex virus, varicellazoster virus, cytomegalovirus,
Epstein-Barr virus
Poxvirus
Yes
Complex
250 x 400
DS, linear
Smallpox virus, vaccinia virus
Classification of RNA Viruses
Virus Family
Envelop
e
Capsid
Size (nm)
Picornavirus
No
Icosahedral
28
Calicivirus
No
Icosahedral
38
Reovirus
No
Icosahedral
75
Flavivirus
Yes
Icosahedral
45
Togavirus
Yes
Icosahedral
60
Retrovirus
Yes
Icosahedral
100
Structure
SS linear,
nonsegmented,
positive polarity
SS linear,
nonsegmented,
positive polarity
DS linear, 10
segments
SS linear,
nonsegmented,
positive polarity
SS linear,
nonsegmented,
positive polarity
SS linear, 2 identical
strands (diploid),
positive polarity
Medically Important
Viruses
Poliovirus, rhinovirus, hepatitis
A virus
Norwalk virus, hepatitis E virus
Rotavirus
Yellow fever virus, dengue
virus, West Nile virus, hepatitis
C virus
Rubella virus
HIV, human T-cell leukemia
virus
Virus Family
Envelope
Capsid
Size (nm)
Structure
Medically Important Viruses
Orthomyxovirus
Yes
Helical
80–120
SS linear, 8 segments,
negative polarity
Influenza virus
Paramyxovirus
Yes
Helical
150
SS linear, nonsegmented,
negative polarity
Measles virus, mumps virus,
respiratory syncytial virus
Rhabdovirus
Yes
Helical
75 x 180
SS linear, nonsegmented,
negative polarity
Rabies virus
Filovirus
Yes
Helical
803
SS linear, nonsegmented,
negative polarity
Ebola virus, Marburg virus
Coronavirus
Yes
Helical
100
SS linear, nonsegmented,
positive polarity
Coronavirus
80–130
SS circular, 2 segments
with cohesive ends,
negative polarity
Lymphocytic choriomeningitis virus
California encephalitis virus,
hantavirus
Hepatitis delta virus
Arenavirus
Yes
Helical
Bunyavirus
Yes
Helical
100
SS circular, 3 segments
with cohesive ends,
negative polarity
Deltavirus
Yes
Uncertain
37
SS circular, closed
circle, negative polarity
Parvovirus
Parvovirus
Parvovirus B19 is a small DNA virus, which belongs to the
genera erythrovirus in the family Parvoviridae; it is the only
known human parvovirus.
Parvovirus B19 is a very small (22-nm) non-enveloped virus
with a single-stranded DNA genome.
- The genome is negative-strand DNA.
- The capsid has icosahedral symmetry.
- There is one serotype.
Transmission
1- The respiratory route
2- transplacental transmission
3-Blood donated for transfusions.
Incubation period: about 12–18 days.
Infectious period: The highest infectivity period is in the
prodromal phase, which is 2 days before the rash
appears, but patients are not infectious after the rash
appears.
Pathogenesis
B19 virus infects primarily two types of cells: (1) red blood cell
precursors (erythroblasts) in the bone marrow, which accounts
for the aplastic anemia, and (2) endothelial cells in the blood
vessels, which accounts for the rash associated with erythema
infectiosum. Immune complexes composed of virus and IgM or
IgG also contribute to the pathogenesis of the rash and to the
arthritis that is seen in some adults infected with B19 virus.
Infection provides lifelong immunity against re-infection.
Clinical Symptoms:
There are five important clinical presentations.

1- Erythema Infectiosum (Slapped Cheek Syndrome,
Fifth Disease)
This is a mild disease, primarily of childhood, characterized
by a bright red rash that is most prominent on the cheeks,
accompanied by low-grade fever, runny nose (coryza),
and sore throat. Erythematous rash appears on the body.
The symptoms resolve in about 1 week.
Fifth disease
Slapped Cheek
Syndrome
 2- Aplastic Anemia: Children with chronic anemia, such as
sickle cell anemia, thalassemia, and spherocytosis, can have
transient but severe aplastic anemia (aplastic crisis) when
infected with B19 virus.
 3- Arthritis
Parvovirus B19 infection in adults, especially women, can
cause arthritis mainly involving the small joints of the hands
and feet bilaterally. It resembles rheumatoid arthritis.
 4- Fetal Infections
If a woman is infected with B19 virus during the first or second
trimester of pregnancy, the virus may cross the placenta and
infect the fetus.
Infection during the 1st trimester is associated with fetal death,
Infection during the 2nd trimester leads to hydrops fetalis
manifests as massive edema of the fetus.
Infection during the 3rd trimester does not result in clinical
findings.
B19 virus is not a common cause of congenital abnormalities
probably because the fetus dies when infected early in
pregnancy.
 5- Chronic B19 Infection
People with
immunodeficiencies,
especially HIV-infected,
chemotherapy, or transplant
patients, can have chronic
anemia, leukopenia, or
thrombocytopenia as a result
of chronic B19 infection.
Laboratory Diagnosis.
Infection control
 Pregnant women who are in contact with a known case of
parvovirus B19 infection should be tested for parvovirus
IgG to establish immunity. Those found to be susceptible
should have a repeat test 4 weeks after contact to ensure
that they have not had a subclinical infection (50% of adults
have subclinical infection).
 Patients should be isolated, if possible, with respiratory
precautions.
 Patients with infection should also be advised to avoid
contact with pregnant women and those who are
immunocompromised or suffer from haemolytic anaemia.
 Healthcare workers who have had significant exposure to
parvovirus B19 infection should be excluded from work from
7 days to 3 weeks after exposure to cover the incubation
period.
Herpesviruses
herpein = creeping.
Herpesviruses
 The herpesviridae family contains eight important human
pathogens: herpes simplex virus types 1 and 2, varicella-zoster
virus,
cytomegalovirus,
Epstein-Barr
virus,
and
human
herpesvirus 6, 7 and 8.
 All herpesviruses are structurally similar.
 Each has an icosahedral core surrounded by a lipoprotein
envelope. The genome is linear double-stranded DNA. They
are large (120–200 nm) in diameter.
 They replicate in the nucleus, form intranuclear inclusions.
HERPES SIMPLEX
VIRUS. Bar, 100nm
 Herpesviruses are noted for their ability to cause latent
infections. In these infections, the acute disease is followed by
an asymptomatic period during which the virus remains in a
latent state.
When the patient is exposed to an inciting agent or
immunosuppression occurs, reactivation of virus replication and
disease can occur.
The herpesvirus family can be subdivided into three categories
based on the type of cell most often infected and the site of
latency.
 1- The alpha herpesviruses, consisting of herpes simplex
viruses 1 and 2, and varicella-zoster virus infect epithelial cells
primarily and cause latent infection in neurons.
2- The beta herpesviruses, consisting of cytomegaloviruses
and human herpesvirus 6, infect and become latent in a variety
of tissues.
3- The gamma herpesviruses, consisting of Epstein-Barr virus
and human herpesvirus 8 infect and become latent primarily in
lymphoid cells.
 Three of the herpesviruses, herpes simplex virus types 1 and
2 and varicella-zoster virus, cause a vesicular rash, both in
primary infections and in reactivations.
 The other two herpesviruses, cytomegalovirus and EpsteinBarr virus, do not cause a vesicular rash.
 Certain herpesviruses are suspected of causing cancer in
humans; e.g., Epstein-Barr virus is associated with Burkitt's
lymphoma
and
nasopharyngeal
carcinoma,
and
human
herpesvirus 8 is associated with Kaposi's sarcoma.
Primary infections are usually more severe than reactivations.
Important Features of Common Herpesvirus Infections.
Primary Infection
Usual Site of
Latency
Recurrent
Infection
Route of
Transmission
Giant Cells
Produced
Fetal or
Neonatal
Disease
Important
HSV-1
Gingivostomatitis
Cranial sensory
ganglia
Herpes labialis,
encephalitis,
keratitis
Via respiratory
secretions and
saliva
Yes
NO
HSV-2
Herpes genitalis,
perinatal
disseminated
disease
Lumbar or sacral
sensory ganglia
Herpes genitalis
Sexual contact,
perinatal infection
Yes
Yes
VZV
Varicella
Cranial or thoracic
sensory ganglia
Zoster
Via respiratory
secretions
Yes
No
EBV
Infectious
mononucleosis
None
Via respiratory
secretions and
saliva
No
NO
Yes
Yes
No
NO
Virus
B lymphocytes
CMV
Congenital
infection (in
utero),
mononucleosis
Monocyte and
lymphocyte
Asymptomatic
shedding
Intrauterine
infection,
transfusions,
sexual contact, via
secretions (e.g.,
saliva and urine)
HHV-8
Uncertain
Uncertain
Kaposi's sarcoma
Sexual or organ
transplantation
Herpes Simplex Viruses (HSV)
HSV-1 and HSV-2 are distinguished by two main criteria:
antigenicity and location of lesions.
Lesions caused by HSV-1 are, in general, above the waist,
whereas those caused by HSV-2 are below the waist.
Transmission
HSV-1 is transmitted primarily in saliva
HSV-2 is transmitted by sexual contact.
Comparison of Diseases Caused by HSV-1 and HSV-2
Site
Disease Caused by HSV-1
Disease Caused by HSV-2
Skin
Vesicular lesions above
the waist
Vesicular lesions below the
waist (especially genitals)
Mouth
Gingivostomatitis
Rare
Eye
Keratoconjunctivitis
Rare
Central nervous system
Encephalitis (temporal
lobe)
Meningitis
Neonate
Rare
Skin lesions and
disseminated infection
Dissemination to viscera
in immunocompromised
patients
Yes
Rare
Pathogenesis
The virus replicates in the skin or mucous membrane at the
initial site of infection, then migrates up the neuron and
becomes latent in the sensory ganglion cells.
The virus can be reactivated from the latent state by a variety of
inducers, e.g., sunlight, hormonal changes, trauma, stress, and
fever, at which time it migrates down the neuron and replicates
in the skin, causing lesions.
When the vesicle ruptures, virus is liberated and can be
transmitted to other individuals.
Multinucleated giant cells are typically found at the base of
herpesvirus lesions.
Incubation period: 2–12 days (mean 4 days).
Infectious period: From the onset of symptoms until the
lesions are fully crusted or resolved.
Clinical Symptoms
I- HSV-1 causes several forms of primary and recurrent
disease:
1- Gingivostomatitis occurs primarily in children and is
characterized by fever, irritability, and vesicular lesions in the
mouth. The primary disease is more severe and lasts longer
than recurrences. The lesions heal spontaneously in 2–3
weeks.
Many children have asymptomatic primary infections.
 2- Herpes labialis (fever blisters or cold sores) is the
milder, recurrent form and is characterized by crops of
vesicles, usually at the mucocutaneous junction of the
lips or nose. Recurrences frequently.
 3- Keratoconjunctivitis is characterized by corneal
ulcers and lesions of the conjunctival epithelium.
Recurrences can lead to scarring and blindness.
Herpes labialis: (fever blisters or cold sores)
 4-
Herpetic whitlow is a pustular lesion of the skin of the
finger or hand. It can occur in medical personnel as a result of
contact with patient's lesions.
 5- Encephalitis caused by HSV-1 is characterized by a
necrotic lesion in one temporal lobe.
Fever, headache, vomiting, and altered mental status are
typical clinical features.
The onset may be acute or protracted over several days.
HSV-1 encephalitis has a high mortality rate and causes
severe neurologic sequelae in those who survive.
 6-
Disseminated infections such as esophagitis and
pneumonia, occur in immunocompromised patients with
depressed T-cell function.
II- HSV-2 causes several diseases, both primary and recurrent
including:
 1- Genital herpes is characterized by painful vesicular
lesions of the male and female genitals and anal area.
The lesions are more severe in primary disease than in
recurrences. Primary infections are associated with fever and
inguinal adenopathy.
Genital Herpes. (a) Herpes simplex virus type 2 (yellow and green) inside an
infected cell. (b) Herpes vesicles on the penis. The vesicles contain fluid that is
infectious.

2- Asymptomatic infections occur in both men (in the
prostate or urethra) and women (in the cervix) and can be a
source of infection of other individuals. Many infections are
asymptomatic; i.e., many people have antibody to HSV-2 but
have no history of disease.
 3- Aseptic meningitis is usually a mild, self-limited disease
with few sequelae.
 4- Neonatal herpes originates from contact with vesicular
lesions within the birth canal.
In some cases, although there are no visible lesions, HSV-2 is
being shed (asymptomatic shedding) and can infect the child
during birth.
Neonatal herpes varies from severe disease (e.g., encephalitis)
to milder local lesions (skin, eye, mouth) to asymptomatic
infection.
Despite their association with neonatal infections, neither HSV-1
nor HSV-2 causes congenital abnormalities to any significant
degree.
Laboratory Diagnosis
Virus culture takes 1–3 days to get a positive result.
Polymerase chain reaction (PCR) can provide a result in a few
hours.
Clotted blood/HSV antibody tests are not useful in the diagnosis
of acute HSV infection but are helpful for epidemiological
studies.
Infection control
 Healthcare staff who have HSV skin lesions on their hands
should cover them with a waterproof dressing to avoid
transmitting infection to patients.
 Cesarean section is recommended for women who are at
term and who have genital lesions or positive viral cultures.
Varicella-Zoster Virus (VZV)
Chickenpox. Lat. varicella = vesicle
Varicella-Zoster Virus (VZV)
Varicella-zoster virus is a double-stranded DNA virus and a
member of the Herpesviridae family of viruses. The same virus
causes both varicella and zoster.
Varicella (chickenpox) is the primary disease; zoster (shingles)
is the recurrent form.
Transmission
The virus is transmitted by respiratory droplets and by direct
contact with the lesions.
Incubation period: 10–23 days (mean 14 days).
Infectious period: From 2 days before the onset of symptoms
until 5 days after the rash or all the skin lesions are fully crusted.
Pathogenesis
VZV infects the mucosa of the upper respiratory tract, then
spreads via the blood to the skin, where the typical vesicular
rash occurs.
Multinucleated giant cells with intranuclear inclusions are seen
in the base of the lesions.
After the host has recovered, the virus becomes latent,
probably in the dorsal root ganglia.
Later in life, frequently at times of reduced cell-mediated
immunity or local trauma, the virus is activated and causes the
vesicular skin lesions and nerve pain of zoster.
Immunity following varicella is lifelong. The frequency of zoster
increases with advancing age, perhaps as a consequence of
waning immunity.
Clinical symptoms
Varicella produces a generalized vesicular skin rash.
The lesions normally first appear on the upper part of the body
before becoming generalized.
The rash involves the whole body, but the lesions are most
dense on the central part of the body (the trunk) as
compared to the limbs.
Lesions continue to appear over the first 48 hours of onset,
and lesions at various stages of development can be seen in
clusters (cropping).
It is usually mild infection in children, but severe infection can
occur, particularly in immunocompromised children.
Adults are at much higher risk of severe or fatal chickenpox,
particularly if they develop varicella pneumonitis, which is
much more common in smokers than non-smokers.
Symptoms are more severe in immunocompromised adults,
and haemorrhagic chickenpox (almost always fatal) with
multiorgan involvement can occur in transplant recipients.
Shingles (zoster) results when VZV reactivates from a dorsal
root ganglion; the virus then travels down a sensory nerve to
the skin supplied by that nerve.
It usually produces a group of fluid-filled blisters (vesicles) on
the skin. Sometimes vesicles do not appear on the skin, but
patients experience pain in the affected dermatome (zoster sine
herpete).
Shingles is often associated with pain (post-herpetic neuralgia),
particularly in older persons, and prompt antiviral treatment
given less than 48 hours after the onset of the symptoms is
indicated in these patients.
Infection in pregnancy
Pregnant women are more likely to have severe symptoms
than other adults.
Chickenpox in the first 20 weeks of pregnancy can result in
severe infection in the fetus (congenital varicella syndrome) in
1–2% cases.
Chickenpox in the last few days of pregnancy can be
problematic for the baby. Babies born to mothers who develop
chickenpox seven days or less before delivery are at significant
risk of severe or fatal chickenpox.
Smallpox (variola_orthopox_virus) Early_Rash_vs_chickenpox
Shingles
Herpes_zoster
Herpes_zoster_shingles
Laboratory Diagnosis
Prophylaxis
There are two vaccines against VZV: one designed to prevent
varicella, called Varivax, and the other designed to prevent
zoster, called Zostavax. Both contain live, attenuated VZV.
The varicella vaccine is recommended for children between
the ages of 1 and 12 years.
 The zoster vaccine is recommended for people older than 60
years and who have had varicella.
Because these vaccines contain live virus, they should not be
given to immunocompromised people or pregnant women.
 Zoster immune globulin or oral aciclovir can be given
prophylactically to reduce the severity of infection or prevent
diseases after exposure. These should be given less than 10
days after exposure to infection.
Cytomegalovirus (CMV)
The name of the virus refers
to the size of the infected
cells, which contain large
intranuclear inclusions.
Cytomegalovirus (CMV)
Cytomegalovirus is a double-stranded DNA virus and member
of the Herpesviridae family of viruses. CMV congenital
abnormalities in neonates.
It is the most common cause of congenital abnormalities.
It
also
causes
pneumonia
immunocompromised
patients
and
and
other
diseases
in
heterophil-negative
mononucleosis in immunocompetent individuals.
Giant cells are formed, hence the name "cytomegalo."
Transmission
Early in life it is transmitted across the placenta, within the birth
canal, and quite commonly in breast milk.
 In young children, saliva is most common mode of
transmission.
 Later in life it is transmitted sexually; it is present in both
semen and cervical secretions.
 It can also be transmitted during blood transfusions and organ
transplants.
Incubation period: 3–6 weeks.
Infectious period: This varies for different groups of people.
a- In immunocompetent people the virus is present for a few
weeks in saliva, blood and some other body fluids after primary
infection.
b- In immunocompromised people the infectious period may be
prolonged after primary infection. Also, when they experience
reactivation of CMV, the infection may last for weeks or months.
Pathogenesis
 Infection of the fetus can cause cytomegalic inclusion
disease, characterized by multinucleated giant cells with
prominent intranuclear inclusions. Many organs are affected,
and widespread congenital abnormalities result.
 Infection of the fetus occurs mainly when a primary infection
occurs in the pregnant woman. The fetus usually will not be
infected if the pregnant woman has antibodies against the
virus.
Congenital abnormalities are more common when a fetus is
infected during the first trimester than later in gestation.
Infections of children and adults are usually asymptomatic,
except in immunocompromised individuals.
CMV enters a latent state in leukocytes and can be
reactivated when cell-mediated immunity is decreased.
CMV can also persist in kidneys for years.
Reactivation from the latent state in cervical cells can result in
infection of the newborn during passage through the birth canal.
Clinical symptoms
Cytomegalovirus infection is usually mild or asymptomatic in
immunocompetent
pregnancy
can
persons.
lead
to
However,
congenital
infection
infection,
in
and
immunocompromised patients (HIV positive, transplant
recipients) often experience severe or fatal infection.
In newborn babies
Symptoms include chorioretinitis, deafness, brain damage,
hepatosplenomegaly, petechial rash, and inter-uterine and
neonatal death.
Laboratory Diagnosis
Infection control
- Cytomegalovirus does not transmit easily between humans in
the absence of sexual or intimate contact.
- It is very rarely transmitted between humans in hospitals.
- Special precautions are not recommended, normal handwashing and universal precautions are sufficient to prevent
transmission of infection in the hospital setting.
Epstein-Barr Virus
(EBV)
Infectious
mononucleosis
(IM); glandular fever; kissing
disease.
Epstein-Barr Virus (EBV)
Epstein–Barr virus is a double-stranded DNA virus and belongs
to the family Herpesviridae.
EBV causes infectious mononucleosis. It is associated with
Burkitt's
lymphoma,
other
B-cell
lymphomas,
and
nasopharyngeal carcinoma.
EBV is also associated with hairy leukoplakia, a whitish,
nonmalignant lesion on the tongue seen especially in AIDS
patients.
EBV is structurally and morphologically identical to other
herpesviruses. The most important antigen is the viral capsid
antigen (VCA), because it is used most often in diagnostic tests.
The early antigens (EA), which are produced prior to viral DNA
synthesis, and nuclear antigen (EBNA), which is located in the
nucleus bound to chromosomes, are sometimes diagnostically
helpful as well.
Transmission
Humans are the natural hosts. EBV infects mainly lymphoid
cells, primarily B lymphocytes.
1- EBV is spread by contact with viral-infected saliva
through coughing, sneezing, kissing, or the sharing of items
2- Some evidence indicates that in teens and young adults
IM is primarily transmitted by sexual intercourse.
Incubation period: 7–14 days in children and teens and 30–60
days in adults.
Infectious period: An infected person can transmit EBV during
clinical period and for as long as five months after symptoms
disappear.
Clinical symptoms
Mononucleosis
Infectious mononucleosis (IM) is teenagers and young adults
may result in acute symptoms that last for several weeks. It
is also called herpes virus 4. It is, also called mono or
glandular fever
Symptoms of IM are particularly common in teenagers. By age
35–40, approximately 95% of the population has been
infected with the Epstein-Barr virus (EBV) that causes IM.
Although anyone can develop mononucleosis, primary
(first) infections commonly occur in young adults between
the ages of 15 and 35.
- Typically IM runs its course in 10–30 days. However people
with weakened or suppressed immune systems, such as AIDS
or organ-transplant patients, are especially vulnerable to
potentially serious complications from mononucleosis.
- Less than 10% of children under age 10 develop symptoms
with EBV infection.
- The first symptoms of IM are usually general weakness and
extreme fatigue. An infected person may require 12–16 hours of
sleep daily prior the development of other symptoms.
- IM symptoms are similar to cold or flu symptoms:
- Fever and chills occurs in about 90% of IM cases. EBV is
most contagious during this stage of the illness.
-
An enlarged spleen, causing pain in the upper left of the
abdomen, occurs in about 50–60% of infections.
- Sore throat and/or swollen tonsils occurs in less than
50% of mononucleosis infections.
- Swollen lymph glands (nodes) in the neck, armpits, and/or
groin develop in less than 50% of infections.
- Jaundice (yellowing of the skin and eyes) develops in more
than 20% of patients, depending on age, and indicates an
inflamed or enlarged liver.
- A red skin rash, particularly on the chest, occurs in about
5% of infections.
- Loss of appetite
- Stomach pain and/or nausea
- Muscle soreness and/or joint pain
- Chest pain
- Headache
- Coughing
- Rapid or irregular heartbeat
These acute symptoms usually last one to two weeks.
- Splenic enlargement generally peaks during the fourth week
after symptoms appear and then subsides. However an
enlarged spleen may rupture in 0.1–0.2% of cases, causing
sharp pain on the left side of the abdomen.
-
Additional symptoms of a ruptured spleen include light-
headedness, a fast heart rate, and difficulty breathing.
- Splenic rupture most often occurs within the first three weeks
and is the most common cause of death from mononucleosis.
Complications of mononucleosis:
Most people with IM return to their normal daily routines within
two to three weeks, although it may take up to six months for
normal energy levels to return.
There
are
other
rare—but
potentially
life-threatening—
complications of mononucleosis:
Neurological complications affecting the central nervous
system may develop in 1–2% of infections.
Bell's palsy is a temporary condition caused by weakened or
paralyzed facial muscles on one side of the face.
The heart muscle may become inflamed.
A significant number of the body's red blood cells or platelets
may be destroyed and there may be reduced number of
circulating red and white blood cells.
EBV infection increases the risk for cancer of the lymphatic
system. The development of two other rare types of cancer—
Burkitt's lymphoma and nasopharyngeal carcinoma—
appears to be associated with EBV.
Diagnosis
A variety of conditions can produce symptoms similar to those
of IM; however if cold or flu-like symptoms persist for longer
than two weeks, mononucleosis may be suspected.
Mononucleosis usually is diagnosed by a blood test—called a
mono spot test—that measures anti-bodies to EBV.
Laboratory diagnosis
Human Herpesvirus 8
(Kaposi's Sarcoma–
Associated
Herpesvirus)
Roseola infantum =
exanthem subitum = sixth
disease.
Human Herpesvirus 8 (Kaposi's Sarcoma–Associated
Herpesvirus)
In 1994, it was reported that a new herpesvirus, now known as
HHV-8, or Kaposi's sarcoma–associated herpesvirus (KSHV),
may be the cause of Kaposi's sarcoma (KS), the most common
cancer in patients with AIDS.
Transmission
Transmission of HHV-8 is primarily sexually, but it is also
transmitted in transplanted organs such as kidneys and appears
to be the cause of transplantation-associated KS.
Clinical Symptoms
dark purple, flat to nodular, and often appear at multiple sites
such as the skin, oral cavity, and soles (but not the palms).
Internally, lesions occur commonly in the gastrointestinal
tract and the lungs. The extravasated red cells give the lesions
their purplish color.
HHV-8 also infects B cells, inducing them to proliferate and
produce a type of lymphoma called primary effusion
lymphoma.
Laboratory diagnosis of KS is often made by biopsy of the
skin lesions. HHV-8 DNA and RNA are present in most spindle
cells, but that analysis is not usually done.
Kaposi's sarcoma