Transfusion Transmitted Disease Flashcards
Attempts to prevent diseases in donated blood
1972 can only accept blood from volunteer (non paid) donors. DHQ and information about high risk lifestyles
Required infectious disease testing (8)
HIV, HCV, HBC, HTLV, WNV, Syphillus, Zika and Chaga’s (Bacteria is tested for as well) (Babesia test may be coming out soon)
HIV required testing
anti-HIV (IGM and IGG) or anti-HIV+O (IgM +IgG)(either ELISA or ChIA) and HIV NAT (RNA) (PCR or TMA)
HCV testing
anti-HCV (IgG) and HCV NAT (RNA)
HBV testing
HbsAg, anti-HBc (IgM and IgG) and HBV NAT (DNA)
HTLV
(both I and II) anti-HTLV I /II(IgG)
Syphillis
Trepanmeal antibody (IgG and IgM) and/or non treponemal RPR testing
WNV
WNV NAT (RNA)
Zika
Zika Virus NAT (RNA)
Chaga’s disease
anti-Trypanosoma cruzii (IgG)
DHQ
tries to screen donors for things we do test for with questions (HIV/HCV etc) Tries to screen donors for things we don’t test for (malaria, CJD, vCJD) and does not have any questions for somethings we DO test for (WNV, Zika, HTLV)
Autologous blood collection must be completed…
72 hours prior to procedure
ELISA 3 different types
enzyme linked immunosorbent assay (Direct, Indirect and Sandwich or capture assay)
Direct EIA
(or elisa) is an antigen of interest immobilized and bound to the well and a target antibody with tag is added to the solution
ELISA sensitivity and specificity
exteremely sensitive, not a lot of false negatives, however not as specific could have high number of false positives
Chia
chemilluminescent immunoassays, variation of colorimetric ELISA test, substrate causes flourescence that reacts with light of certain wavelength
What is the antibody with attached signal molecule that binds in an ELISA assay
conjugate antibody
What causes an enzymatic color change in ELIZA
substrate
Indirect EIA
antigen is immobilized and bound to well/plate, antibody of patient (if present) then binds to antigen,
sandwich EIA
Antibody (capture antibody) is bound to well, antigen in the patient binds to these antibody (if present) second conjugate antibody with tag binds to first antibody, chemical change causes colorimetric change for identification
Conjugate
conjugated to enzyme that causes indicative change with addition of substrate, antibody that binds either Fc portion of target antibody, or to target antigen
If serologic testing is positive
Donor must be deferred, however there is a large percentage of false positives, donor can potentially be eligible for re-entry later
Confirmatory Testing
FDA mandates that supplemental or confirmatory testing if available
If initial sample test is reactive:
repeat the sample in duplicate, if either of the repeated samples are positive, unit must be discarded and supplemental testing performed if available. IF both repeated samples are negative, unit can be released.
Substrate
added at the very end in order to stimulate the enzyme into a colorimetric or fluorescent change for detection
NAT
Nucleic acid test, became licensed in 2002 this is highly specific testing, detects either RNA or DNA through amplification of specific nucleotide sequence
MP
minipool (about 16 donors) pool the blood together to do NAT testing, can rule out all at once if negative, if positive need to determine which one is positive by repeating NAT individually
Advantage of NAT
reduces the ‘window period’ (HIV, HCV, HBV) can detect before antibodies are able to be made (WNV, Zika)
HIV
Human immunodeficiency virus, Single stranded RNA, two main types HIV-1 and HIV-2 has several groups (M, N, O and P-most infections worldwide are M ) HIV-2 is less infectious, typically associated west africa. Transmission is 25% infectious- paternal, sexual, blood exposure. Infects CD4 helper T cells
TMA
transcription mediated amplification
HIV deferal
permanent deferral if antibody and HIV-1 RNA is positive. If serology is negative but HIV-1 RNA is positive-indefinte referral until further testing is done
HIV supplemental testing to anti-HIV 1/2
hiv-1 rna can be used as supplemental testing (if negative can use HIV-1 western blot or HIV-1 IFA)
IFA
indirect immunoflourecence assay **
With NAT the window for HIV is approximately how many days?
9 days
HBV
Douple straned DNA hepadnavirus, this virus is much more hardy than HIV and can live on surfaces for weeks . There are two serological markers for this HbsAf and antibody to hepatitis B core antigen. with three markers, result outcome can be complex
Hepatitis B surface antigen
detection using either EIA or ChIA, if positve sample repeated in duplicate, if supplemental test result is positive donor is permanently deferred, if not confirmed with supplemental test donor can be reentered in 56 days (8 weeks)
Positive HbsAg negative supplemental tests
reentry of donor after 56 days/8 weeks
Supplemental testin for HbsAG
HBV-NAT can be used as supplemental i negative or not already being used as supplemental
If anti-Hbc is positive
indefinite deferral when positive >1time, permanent deferral if HbsAg is also positive
HBV NAT positive
permanent deferral if HbsAg is also positive. Indefinite deferral with reentry option if all serological tests are nonreactive
NAT negative
if negative, only positive is confirmation for other tests, in order to be an acceptable negative results other testing needs to be performed.
ANA IFA
antinuclear antibodies and Indirect flourescence assay., performed for autoantibodies is autoimmune disorders. SLE almost always positive
HCV
hepatitis C virus, lipid enveloped single stranded RNA flavavirus, transmission rate is lower than HIV and HBV, same types of transmission. Most infected people develop chronic infection (75-85%) Currently no confirmatory assay except HCV NAT
Anti-HCV
IgG test ELISA or Chia, HCV NAT is currently the only true confirmation testing available. If HCV NAT is negative it is recommended to perform an alternate manufacturers antibody test for donor counseling
HCV NAT positive
if anti-HCV is negative, indefinite deferral. Donor may be retested for reentry after 6 months. Permanent deferral if both are positive.
HTLV
Human T cell lymphotropic virus, enveloped single stranded RNA retrovirus, both HTLV and HIV have reverse transcriptase enzyme, infects T lymphocytes, Transmission: blood, sexual, vertical (especially breast feeding)
Parenteral
administered or occuring elsewhere in the body than the mouth
HTLV associated diseases
Adult T-cell leukemia, HTLV associated myelopathy and Tropical spastic paraperesis
Myelopathy
injury to the spinal chord from trauma or disease etc.
HTLV required test
IgG antibody to HTLV
supplemental testing for HTLV
western blot, line assay, IFA or RIPA
Positive HTLV
1ST occurrence 56 day deferral, 2nd occurrence indefinite deferral
Syphilis
caused by bacterium Treponema Pallidium, transmission is parental mainly sexual. May indicate high risk behavior
Syphilis screening
terponemal specific testing: microhemagllutingation (MHA-TP)or EIA. OR non-teronemal markers (RPR, VDRL)
Syphilis postive
12 month deferral
RPR test
either solid phase red cell adherance or particle agglutination
Syphilis supplemental assay
antigen specific immunoflourescence (FTA-ABS, EIA, or MHA-TP)
Chaga’s disease
caused by parasite, trypanasoma cruzii, carried in feces of triatomine insects (kissing bugs) most often no symptoms, disease can eventually cause cardiomyopathy and/or GI motility problems, vertical transmission is prevalent. Most blood centers test each donor only once
Chaga’s positive test
indefinite deferral if supplemental test is negative, reentry option is available after 6 months
Chaga’s supplemental test
ESA (licensed) or RIPA (unlicensed)
Chaga’s required test
IgG antibody to T. Cruzii through EIA OR Chia
WNV
single stranded RNA flavivirus, natural cycle in transmission between birds and mosquitos, humans horses and other mammals can be affected
Mosquito species that infects
Culex mosquitos
Symptoms of WNV
80% of those infected do not have symptoms, can cause fever, rash, headache and fatigue (1% have severe symptoms, encephalitis/meningitis)
Incubation period for WNV
2-14 days
positive donors
presumed viremic positive donors (PVD) are deferred for 120 days
Zika Virus
single stranded RNA flavavirus
Zika virus mosquito
Aedes, also carries Dengue, Chikungunya, Yellow fever, also can be trasmitted in utero, perinatal and sexually.
Zika symptoms
most people are asymptomatic , typical symtoms are fever with maculopapular rash, arthralgia or conjunctivits
Zika additonal problems
birth defects, causes microcephaly and brain disorders in infants born to mothers who were infected with Zika during pregnancy, also linked to cases of guillian-Barre syndrome in patients after zika infection
WNV and ZIKV testing
pooled or individual TMA or PCR
WNV and ZIKV supplemental testin
Repat RNA test (for WNV) , IGM and IGG antibody tests (for both)
WNV or ZIKV positive
120 day deferral regardless of supplemental test results. Donor is then eligible for reinstatement
Babesia
caused most commonly by babesia microti-protozoan, tick born disease most common in northeast and north midwest.
Testing for Babesia
NAT nad antibody tests for detection were licensed in 2018, draft guidance has been issued for testing in selected states
CMV
cytomegalovirus, present in 40-70% of population, testing all donors is not a requirement, leukoreduction may reduce or prevent post-transfustion CMV infections
Other blood born diseases with no FDA licensed test
malaria, CJD, vCJD, Dengue, Chikungunya, Leishmaniasis
Bacterial Detection in Platelets
1 risk is platelets, due to room temperature storage
Bacterial risk per platelet
1 in 2300, most often it is bacteria contaminants found on the skin
Donor reentry process
Process for requalification of donors who have been deferred due to false positive results.
Donor reentry deferral period
2-6 months and most require specific testing to be performed with negative results
FDA has issued guidance for reentry for which infectious disease TESTS :
Anti-HIV 1/2, Anti-HCV, Hbsag, anti-HBc, Syphilis, HIV/HCV/HBV NAT and Chaga’s antibody
testing needed for reentry
usually involves performing on a new sample the original serologic test if available and a discriminatory NAT if applicable
anti-HCV and HCV NAT reentry
after 6months of deferral, test follow up sample with HCV NAT and two different licensed anti-HCV screenign tests
Upon reentry HCV NAT test positive
defer donor permanently regardless of what ant-HCV test result
Upon reentry HCV NAT negative, anti-HCV positive with both tests
defer donor permanently
Upon reentry HCV NAT nonreactive, one anti-HCV positive and on anti-HCV negative
Defer donor and continue follow up
Upon reentry HCV NAT negative and both anti-HCV tests negative
reenter donor, donor eligible for future donation provided donor meets eligibility criteria
Upon reentry any positive test for anti-HBc
deferred indefinitely
Upon reentry any positive test for anti-HBc
minimum of 8 weeks after initial positive test and deferral, donor may apply for reentry, if any positive test donor is deferred indefinitely
Donor reentry anti-HBc test positive process
minimum of 8 weeks after solely repeatedly reactive (RR) anti-HBc positive test, patient can be tested for reentry.. Follow up sample can be drawn and tested using FDA licensed testing HbsAG, anti-HBV and HBV NAT
HBV immunization markers
can be present from the HB vaccine for several weeks after given, you could falsely test positive if given the vaccine and be deferred
HBsAg
An antigen that indicates the presence of Hepatitis B virus. A positive test for HBsAg indicates active Hepatitis B infection
HBV NAT positive indicates:
A blood test that detects the presence of nucleic acids specific to Hepatitis B virus. A positive test indicates active Hepatitis B infection.
HBsAg and anti-HBc, which is the first marker
HBsAg rises quicker in the patient and is the first detectable marker of HBV infection
anti-Hbs
arises after Anti-Hbc and anti-Hbe
