Transcript lecture7

TORCH tsets
• The five categories of organisms whose antibodies are mea
sured by theTORCH test are grouped together because they
can cause abortion for pregnant woman and/or birth
defects in newborns.
• Toxoplasmosis.
• Others e.g: Chlamydia, syphilis, hepatitis B, coxsackie virus, EpsteinBarr virus, varicella-zoster virus(chickenpox), and humanparvovirus.
• Rubella.
• Cytomegalovirus(CMV).
• Herpes(HSV)
• There are several causes for abortion, some of
them are related to viral infection from these
viruses:
1. Cytomegalovirus ( CMV).
2. Rubella.
3. Herpes.
• Other non-viral causative agents for abortion
include:
–
–
Clamydia
Toxoplasma gondii (parasite)
• Toxoplasmosis is a zoonotic disease caused by infection
with the protozoan Toxoplasma gondii
• Toxoplasmosis may cause flu-like symptoms in some
people, but most people affected never develop signs
and symptoms.
• For infants born to infected mothers and for people
with weakened immune systems, toxoplasmosis can
cause extremely serious complications.
• An obligate intracellular parasitic protozoan.
• T. gondii is capable o f infecting virtually all warmblooded animals(lack of host specificity).
• Cats are the definitive hosts in which the parasite
can undergo sexual reproduction.
• During infection two forms of parasite may form:
– Tackyzoit: Rapidly growing form (acute infection).
– Bradyzoit: Slowly growing form in cysts ( chronic
infection).
• Tissue cysts formed in any organ especially brain,
eyes and strained muscles.
• Eating undercooked, contaminated meat .
• Eating food that was contaminated by
knives, utensils, cutting boards and other
foods that have had contact with raw,
contaminated meat (cross
contamination).
• Drinking water contaminated
with Toxoplasma gondii.
• Mother-to-child (congenital)
transmission.
• Accidentally swallowing the
parasite through contact with cat
feces that contain Toxoplasma.
• Receiving an infected organ
transplant or infected blood via
transfusion, though this is rare.
• Toxoplasmosis is usually nothing to worry about
because the immune system is normally strong enough to
fight the infection and stop it from causing serious illness.
After getting the infection, most people are immune to it
for the rest of their life.
• However, it can lead to serious problems in:
– women who become infected while they're pregnant
Toxoplasmosis could cause a miscarriage or stillbirth, or the infection could
spread to the baby and cause serious complications (congenital toxoplasmosis)
– people with weak immune systems.
Such as those who've had an organ transplant, those with HIV and those having
chemotherapy this could mean the infection is able to spread to the eyes, heart,
lungs or brain
• Approximately 10-20% of pregnant women
infected with T gondii become symptomatic, The
most common signs of infection are
lymphadenopathy and fever.
• When a mother is infected with T gondii during
gestation, the parasite may be disseminated
hematogenously to the placenta. When this
occurs, infection may be transmitted to the fetus
transplacentally.
If infection was shortly before conception
(within a few weeks before):
– carries a one percent risk or below of
transmission to the baby, but there is a risk of
miscarriage if the baby does become infected.
If infection was in the first trimester (week one to 12)
– carries about 10-15 percent risk of transmission
to the baby. A baby infected at this stage has a
risk of being miscarried or stillbirth.
If infection was in the second trimester (week 13 to 28):
– about 25 percent risk of transmission. A baby infected
at this stage is less likely to be miscarried, but is still at
risk of developing severe symptoms as:
• Hydrocephaly (water on the brain)
• Calcifications of the brain
• Retinochoroiditis (inflammation of the
retina)blindness
• Microcephaly.
• Neurological disorders.
If infection was in the third trimester (week 29 to 40)
– Risk of transmitting the infection rises again if
toxoplasmosis is caught at this stage of pregnancy, and
may be as high as 70–80 percent.
– Most babies infected will be apparently healthy at birth,
but a large proportion will develop symptoms later in life,
usually eye damage and Neurological problems .
Retinochoroiditis (ocular toxoplasmosis)
• Retinochoroiditis usually results
from reactivation of congenital
infection, or a part of acute
infection.
• When the organism reaches the
eye through the bloodstream,
depending on the host's
immune status, a clinical or
subclinical focus of infection
begins in the retina.
• As the host's immune system responds, the cyst forms
which is resistant to the host's immune system, and a
chronic, latent infection ensues.
• The cyst remains in the normal-appearing retina.
• Whenever the host's immune function declines for any
reason, the cyst wall rupture, releasing organisms into the
retina, and the inflammatory process starts. If an active
clinical lesion is present, healing occurs as a
retinochoroidal scar.
serologic tests.
 Amplification of specific nucleic acid sequences
(i.e., polymerase chain reaction [PCR]).
Histologic demonstration of the parasite and/or
its antigens (i.e., immunoperoxidase stain).
Isolation of the organism.
Other rarely used methods include:

– Demonstration of antigen in serum and body
fluids.
– Atoxoplasmin skin test.
– Antigen-specific lymphocyte transformation.
• Serologic testing:
• Different serological tests often
measure different antibodies that
possess unique patterns of rise and
fall with time after infection.
• A combination of serological tests is
frequently required to establish
whether an individual has been more
likely infected in the distant past or
has been recently infected.
• IgG antibodies:
– IgG antibodies usually appear
within 1–2 weeks of acquisition
of the infection, peak within 1–
2 months, decline at various
rates, and usually persist for
life.
– The most commonly used tests
for the measurement of IgG
antibody are the Sabin-Feldman
Dye Test (DT), ELISA, IFA, and
the modified direct
agglutination test.
• IgM antibodies:
– IgM antibody titres rise from 5
days to weeks following acute
infection, reaching a maximum
within 21 days and decline
more rapidly than IgG.
– The most commonly used tests
for the measurement of IgM
antibody are ELISA kits, the IFA
test, and the immunosorbent
agglutination assay (ISAGA).
Note: Ecteric phase is the period when switching b/w IgG
and IgM production ocure results in low levels of both.
• IgA Antibodies:
– IgA antibodies may be detected in sera of
acutely infected adults and congenitally
infected infants using ELISA or ISAGA
methods.
– It appears in sera when the parasite attacks
the eye (toxoplasmic chorioretinitis).
– In a number of newborns with congenital
toxoplasmosis and negative IgM antibodies,
the serological diagnosis has been
established by the presence of IgA and IgG
antibodies.
• IgE Antibodies:
– IgE antibodies are detectable by ELISA in sera of
acutely infected adults, congenitally infected
infants.
– The duration of IgE seropositivity is less than with
IgM or IgA antibodies and hence appears useful
as an adjunctive method for identifying recently
acquired infections.
• Histologic diagnosis:
– Diagnosis also can be made by direct observation of
the parasite in stained tissue sections from biopsy.
– Immunoflorscence stain and sabin field man stain can
be used.
– These techniques are used less frequently because of
the difficulty of obtaining these specimens.
• Isolation:
– Parasites can also be isolated from blood or other body
fluids by animal inoculation or cell cultures, but this
process can be difficult and requires considerable time.
• PCR:
– Molecular techniques that can detect the parasite's
DNA in the amniotic fluid can be useful in cases of
possible mother-to-child (congenital) transmission.
– Amniocentesis:
• to identify T. gondii in the amniotic fluid by PCR (the most
sensitive and specific), done if serologic testing cannot
confirm or exclude acute infection, and if there are abnormal
ultrasound findings suggestive of toxoplasmosis infection.
– Fetal blood sampling (cordocentesis):
• was previously the gold standard for diagnosing fetal
infection but no longer, because of the associated higher
fetal risk
• Ocular disease is diagnosed
based on the appearance of
the lesions in the eye,
symptoms, course of disease,
and often serologic testing
and measuring the level of
IgA.
• There are 2 goals of drug therapy for
toxoplasmosis, depending on whether or not
fetal infection has occurred.
– If maternal infection has occurred but the fetus is
not infected, spiramycin is used for fetal
prophylaxis (to prevent spread of organisms
across the placenta from mother to fetus).
– If fetal infection has been confirmed or is highly
suspected, pyrimethamine and sulfadiazine are
used for treatment and decrease in disease
severity.
• Do not eat undercooked meat.
• Wash hands after handling raw meat.
• Keep children's play areas free from cat and
dog feces.
• Wash your hands thoroughly after
touching soil that may be contaminated with
animal feces.
Chlamydia
• Small obligate intracellular parasite.
• Confusion occurred by the discovery of Chlamydia as
it was classified as both bacteria and virus.
• It is classified as virus for it’s:
– Basophilic staining in the host cell to form the
elementary body, which are small, dense and
about 0.3u in diameter.
– Intracellular microorganism, they can’t synthesize
ATP, but use the host cell for this purpose.
• Causes for classification of chlamydia as
bacteria:
– They have both DNA and RNA.
– Have their self-metabolic system.
– They are able to grow and multiply by
binary fission.
– They are surrounded by a cell membrane.
– Response to antibiotic therapy.
Species of chlamydia
1. C. psittsci, cause psittacosis.
2. C. lymphogranulomatis, cause
lymphogranuloma venerum ( LGV).
3. C. trachomatis, cause conjuctival and
cornea disease (Trachoma)
4. C. occulogenitalis, cause conjunctivitis.
• Psittacosis:
– Is a respiratory disease of man acquired
from contact with infected birds, which
excretes the organism in their stool.
– It causes infection in the upper respiratory
system and pneumonia.
• Laboratory diagnosis:
1. Sputum and blood test.
• Smear to show elementary bodies.
• ELISA.
• PCR
2. isolation: by inoculation of the yolk sack
of an embryonated egg or intracerebral,
intranasal or intraperitonial injection into
a mice.
3. Serological tests:
– Complement fixation.
– Agglutination test.
– Neutralization test.
• Lymphogranuloma venerum:
– It is a venereal disease characterized by:
• Enlargement of lymph regional lymph nodes,
tend to form sinuses.
• Infect the urethral parts and cause urethritis
and is accompanied by systemic symptoms.
– Laboratory diagnosis:
• Smears (biopsy from the infected lymph
node), pus cells can be seen in infected
LN and stain (elementary bodies)
• Culture: is not useful as it will give
negative result and resist all antibiotics.
• C. Trachomatis:
– Causes Chlamydial infection which is a
sexually transmitted disease (STD)
– Causes Trachoma by it’s growth in
the conjunctival and cornea cells
of the eye causing keratoconjunctivitis.
– If passed to the baby during the
passage through the birth canal,
chlamydia can cause conjunctivitis
and pneumonia.
– Many women who are infected do not even
realize it because they often have no symptoms.
However, when untreated, chlamydia can cause a
scarring infection of the woman's internal
reproductive organs, increasing her risk of a
potentially fatal tubal pregnancy.
– Laboratory diagnosis:
• Smear(eye swab).
• ELISA (IgM, IgG or IgA).
Rubella
• Rubella is a rather mild disease spread
by the way of respiratory secretion, skin
contact or congenitally.
• Cause German measles, causing the
following symptoms:
– Firstly, catarrhal symptoms and mild fever.
– Irregular rash.
• Incubation period is (3-4) weeks.
• The tragic aspect of Rubella may
become evident of infection occurs
during pregnancy.
• MMR vaccine .(IgG pesist for life)
symptoms
• The virus can cross placental wall and infect the
fetus, this may lead to fetal death or congenital
defect which may be:
–
–
–
–
–
–
–
Hearing loss
Mental retardation
heart disease
retarded growth
blood disorders
vision problems
pneumonia
Laboratory Diagnosis
•
•
•
•
Complement fixation.
Neutralization test.
Heme agglutination inhibition (HAI).
ELISA IgM and IgG.
Herpes Human Viruses (HHV)
• There are eight types of herpes viruses known to
affect humans:
• HSV1 (Herpes Simplex Virus 1 commonly known as
oral herpes)
• HSV2 (Herpes Simplex Virus 2 commonly known as
genital herpes)
• HHV3 - VZV (Varicella Zoster Virus commonly known
as chickenpox or shingles)
• HHV4 - EBV (Ebstein Barr Virus commonly known as
infectious mononucleosis [mono or glandular fever])
• HHV5 - CMV (Cytomegolo Virus is the most common
virus transmitted to a pregnant woman's unborn
child)
• HHV6 - Roseolovirus more commonly known as the
6th disease or Roseola Infantum
• HHV7 - Similar to HHV6 (not yet classified)
• HHV8 - A type of rhadinovirus known as the Kaposi's
sarcoma-associated herpesvirus (KSHV)
Herpes simplex virus
• There are two forms of the herpes simplex virus:
– Herpes simplex virus 1 (HSV-1)
– Herpes simplex virus 2 (HSV-2)
.
Area of infection
Transmission
HSV-1
HSV-2
Oral cavity(mouth)
Genital area
By contact
sexually
HSV-1
• also commonly referred to as fever blisters, oral
herpes.
• It is a viral infection of the skin that may occur
once or return again and again.
• some factors that may trigger it to return:
– Stress
– Fever
– Menstruation Cycle
– Fatigue
– Certain foods
– Pregnancy
HSV-2
• Genital herpes outbreaks are contagious viral
infection that affects primarily the genitals of men
and women.
• It is characterized by recurrent clusters of lesions in
the genital areas.
• It is sexually transmitted (STD)
Varicella zoster
• Infection with the varicella virus can cause chicken
pox and shingles
• It can be spread through contact with the sneezes or
coughs of an infected person.
• becoming infected during pregnancy can cause
serious complications to newborn:
– Scarring
– malformed limbs
– damage to the eyes and brain.
Diagnosis of HSV and herpes zoster
1. Viral culture.
2. Tzanck smear.
3. Direct immunofluorescence study with monoclonal
antibodies (DFA)
4. PCR
5. Type-specific serologic tests for HSV.
Cytomegalo virus (CMV)
• CMV is also called salivary gland virus which may
infect salivary glands or parotid gland.
• An increase number of infections with the virus
have reported in adults with neoplastic disease,
leukemia or tissue transplation.
• we can isolate this virus from all body fluids.
Symptoms of congenital CMV
• 90% of congenital CMV cases are asymptomatic
at birth.
• 0.5 – –15% of these are at risk for psychomotor,
hearing, neurologic, ocular, or dental
abnormalities within first few years of life.
microcephaly, seizures, petechial rash also can
be manifeted.
• 10% of cases may have sensorineural hearing
loss.
Laboratory diagnosis
• Histopathological studies, this virus leads to the
formation of certain inclusion in the infected cells.
• Virus isolation.
• ELISA(IgM and IgG)
– Note: when we measure IgG, it rarely negative
and often positive, so we determine the titer,
suppose it is 300 IU/ml, after 2-3 weeks we make
follow up and do the CMV again:
• The titer in the same level or less it is negative.
• The titer is higher, it is positive.