Transcript TORCH Infections

‫بسم هللا الرحمن الرحيم‬
Faculty of Allied Medical
Sciences
Clinical Immunology & Serology
Practice
(MLIS 201)
TORCH
Prof. Dr. Ezzat M Hassan
Prof. of Immunology
Med Res Inst, Alex Univ
E-mail: [email protected]
Objectives
• To Know elements of TORCH
• To know the causes of TORCH Infection
• Describe the diagnostic methods for TORCH
TORCH Infections
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T=toxoplasmosis
O=other (syphilis ,HBV,HIV ,)
R=rubella
C=cytomegalovirus (CMV)
H=herpes simplex (HSV)
Index of Suspicion
• When do you think of TORCH infections?
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Intra-Uterine Growth Retardation (IUGR) infants
Hepato-Splenomegaly (HSM)
Thrombocytopenia (Low Platelet count)
Unusual rash
Concerning maternal history
“Classic” findings of any specific infection
TORCH - panel (IgM & IgG)
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Toxoplasma
Rubella
Cytomegalo virus
Herpes
• IgM - Acute or Recent infection
• IgG - Chronic infection
Diagnosing TORCH Infection
• Good maternal/prenatal history
• Remember most TORCH infections are
mild illnesses & often unrecognized
• Thorough exam of infant
• Directed labs/studies based on most
likely diagnosis…
Syphilis
• Treponema pallidum (spirochete)
• Transmitted via sexual contact
• Placental transmission as early as 6wks
gestation
Clinical Manifestations
• Fetal:
• Stillbirth
• Neonatal death
• Hydrops fetalis
• Intrauterine death in 25%
• Perinatal mortality in 25-30% if
untreated
Diagnosing Syphilis
(Not in Newborns)
• Available serologic testing
• RPR/VDRL: nontreponemal test
• Sensitive but NOT specific
• Quantitative, so can follow to determine disease activity
and treatment response
• MHA-TP/FTA-ABS: specific treponemal test
• Used for confirmatory testing
• Qualitative, once positive always positive
• RPR/VDRL screen in ALL pregnant women
early in pregnancy and at time of birth
• This is easily treated!!
Treatment
• Penicillin G is THE drug of choice for ALL
syphilis infections
• Maternal treatment during pregnancy very
effective (overall 98% success)
Rubella
• Single-stranded RNA virus
• Vaccine-preventable disease
• No longer considered endemic in the U.S.
• Mild, self-limiting illness
• Infection earlier in pregnancy has a
higher probability of affected infant
“Blueberry muffin” spots representing
extramedullary hematopoesis
Diagnosis
• Maternal IgG may represent immunization or
past infection - Useless!
• Can isolate virus from nasal secretions
• Less frequently from throat, blood, urine, CSF
• Serologic testing
• IgM = recent postnatal or congenital infection
• Rising monthly IgG titers suggest congenital
infection
• Diagnosis after 1 year of age difficult to
establish
Treatment
• Prevention…immunize, immunize,
immunize!
• Supportive care only with parent
education
Cytomegalovirus (CMV)
• Most common congenital viral infection
• ~40,000 infants per year in the U.S.
• Mild, self limiting illness
• Transmission can occur with primary infection
or reactivation of virus
Clinical Manifestations
• 90% are asymptomatic at birth!
• Up to 15% develop symptoms later,
• Symptomatic infection
• HSM, petechiae, jaundice, neurological
deficits
• >80% develop long term complications
• Hearing loss, vision impairment, developmental
delay
Diagnosis
• Maternal IgG shows only past infection
• Infection common – this is useless
• Viral isolation from urine or saliva in 1st
3weeks of life
• Viral load and DNA copies can be assessed
by PCR
• Less useful for diagnosis, but helps in following
viral activity in patient
• Serologies not helpful given high antibody in
population
Herpes Simplex (HSV)
• HSV1 or HSV2
• Primarily transmitted through infected
maternal genital tract
Clinical Manifestations
• Most are asymptomatic at birth
• 3 patterns of symptoms between birth and
4wks:
• Skin, eyes, mouth (SEM)
• CNS disease
• Disseminated disease (present earliest)
Presentations of congenital HSV
Diagnosis
• Culture of maternal lesions if present at
delivery
• Cultures in infant:
• Skin lesions, oro/nasopharynx, eyes, urine, blood,
rectum/stool, CSF
• CSF PCR
• Serologies again not helpful given high
prevalence of HSV antibodies in population
Treatment
• High dose acyclovir 60mg/kg/day
divided q8hrs
• X21days for disseminated, CNS disease
• X14days for SEM
• Ocular involvement requires topical
therapy as well
Taxoplasmosis
(Toxoplasma gondii Infection)
Toxoplasma gondii
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Worldwide Intracellular paradite.
All parasite stages are infectious.
Domestic Cat is the Definitive Host
Infects animals (cattle, birds, rodents, pigs&
sheep)and humans as Intermediate Hosts.
Toxoplasma gondii (Cont.)
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Causes the disease Toxoplasmosis.
Toxoplasmosis is leading cause of
abortion in sheep and goats.
Risking group: Pregnant women, meat
handlers (food preparation) or anyone
who eats the raw meat
Toxoplasma gondii
Transmission
 Contaminated water or food by oocysts
Undercooked infected meat.
Mother to fetus.
Organ transplant (rare).
Blood transfusion (rare).
Oocytes do not become infectious until
they sporulate, sporulation occurs
1- 5 days after that the oocyte is excreted
in the feces.
Tissue phase (intermediate hosts).
Human, cattle,
birds, rodents,
pigs, and sheep.
Intermediate host gets
infected by ingesting
sporulated oocysts.
Intermediate host
CLINICAL MANIFESTATIONS
• Acute toxoplasmosis is usually asymptomatic
and self-limited.
• In some case of acute toxoplasmosis cervical
lymphadenopathy, headache, malaise, fatigue,
and fever may appear
• It causes sever complications in
eyes and brains of infected new born
babies
• Toxoplasmosis causes repeated
abortion in pregnant females
Lab Diagnosis
1) Microscopic demonstration of the T. gondii
organism in blood, body fluids, or tissue.
2) Detection of T. gondii antigen in blood or body
fluids by ELISA technique.
3) Serological diagnosis for antibodies by
 Sabin-Feldman dye test
 IHA
 ELISA
 IFAT
 Latex agglutination Test
All measure circulating antibodies to Toxoplasma.
Lab Diagnosis (Cont.)
6) Polymerase Chain Reaction (PCR) on body
fluids, including CSF, amniotic fluid, and blood.
7) Skin test results showing delayed skin
hypersensitivity to Toxoplasma gondii antigens.
8) Antibody levels in aqueous humor or CSF may
reflect local antibody production and infection.
9) Animal inoculation: inoculation of suspected
infected tissues into experimental animals.
10) Culture: inoculation of suspected infected
tissues into tissue culture.
Sabin-Feldman dye test
• Live virulent tachyzoites of T gondii are used as antigen
• The parasites are mixed with dilutions of the test serum +
complement obtained from Toxoplasma-antibody freehuman serum + Methylene blue dye.
• After one hour incubation at 37o C the parasites are
examined microscopically for dye staining
• organisms are lysed if the patient has T gondii-specific IgG
antibody and they do not stained with the dye
• Parasites stained with dye
Negative
• This test is sensitive and specific for toxoplasmosis.
• It is available mainly in reference laboratories
• A negative test result practically rules out prior T
gondii exposure
• Its main disadvantages are
 high cost
 human hazard of using live organisms.
SABIN –FELDMAN DYE TEST
Live tachyzoites +Complement+Test serum
Methylene Blue Dye
Incubation at 370 C for one hr.
+ve
If Abs are present
<50% of tachyzoites
do not stain .
-ve
If Abs are absent
90-100 %
tachyzoites Stain
indirect fluorescent antibody
test (IFAT)
• Overcomes some of the disadvantages of the dye
test.
• In IFAT, killed tachyzoites of Toxoplasma, which
are available commercially, are used as antigen.
• Titers obtained by IFAT are similar to those from
the dye test.
• Disadvantages of the IFAT are
 Fluorescent microscope is needed, fluorescent
 false-positive titers may occur in hosts with antinuclear antibodies.
indirect fluorescent antibody
test (IFAT)
• Other serologic tests including the
hemagglutination test, the latex
agglutination test and ELISA offer some
advantages.
• For example, agglutination tests are easy
to perform and cheap.
Agglutination IgG test
• This test uses formalin-preserved whole
tachyzoites to detect IgG antibody.
• It is sensitive to IgM antibodies, which can
cause a nonspecific agglutination in sera
• This problem is avoided by pretreatment of
samples with 2-mercaptoethanol .
• This method is simple, relatively inexpensive,
and excellent for screening pregnant patients,
• It should not be used to measure IgM
antibodies specific for T gondii.
Toxoplasmosis IHA Test
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APPLICATION: To detect Toxoplasma IgM
antibodies by indirect haemagglutination test.
The reagent for this test consisted of stabilized
human red cells coated with a Toxoplasma gondii
heat-stable alkaline-solubilized extract
react predominantly with IgM antibodies found in
serum samples from patients with a recent infection
INTERPRETATION OF RESULTS:
Results will be reported as:
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Positive
Doubtful
Negative
Doubtful results should be retested within 2 weeks.
In ocular Toxoplasmosis, titres of antibodies may
be very low.
Toxoplasma IgM Elisa
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APPLICATION: For measurement of the
IgM antibodies to toxoplasma gondii in
human serum and plasma to aid in the
diagnosis of primary infection.
INTERPRETATION OF RESULTS:
A. Negative :
B. Equivocal :
C. Positive
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< 0.500 (arbitrary units)
0.500 - 0.599
≥ 0.600.
This applies to the diagnosis of Acute T. gondii infection
acquired during pregnancy
COMMENTS
• Diagnosis of acute infection with T. gondii can be
established by detection of the presence of IgG and IgM
antibody to Toxoplasma in serum.
• The presence of circulating IgA favors the diagnosis of
an acute infection.
• Maternal IgG testing indicates past
infection (but when…?)
• The parasite can be isolated in culture
from placenta, umbilical cord, infant
serum
• PCR testing on WBC, CSF, placenta
• Not standardized
Comments
• Persisting IgM levels may be
detected long after the onset of
acquired infection
• Thu,s the use of a single serological
test result must be used with caution
in those cases when it is critical to
establish the time of infection.
• This applies to the diagnosis of
Acute T. gondii infection acquired
during pregnancy
Treatment
• Treatment of cases with acute toxo
• Spiramycin aantibiotic daily
Study Questions:
• Write a short note on:
Diagnostic methods for CMV.
‫‪Assignment‬‬
‫‪• Diagnostic methods for Toxoplasmosis‬‬
‫روان رزق – ريوان ابراهيم – فاطمة الزهراء – منى يحيى – نجاتو عثمان‬
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