COLLECTIONS - Donor Selection Criteria Flashcards
What is the selection criteria for blood donors?
- New donors: 16 - 65 y/o Repeat donors: 16 - 70 y/o
- At least 50 kgs
- Of adequate haemoglobin levels 120 g/l for females. 130 g/l for males.
- In general good health determined by questionnaire.
- Not pregnant or breastfeeding.
What reasons would permanently defer you from donating blood?
- Anything to do with the Creutzfeldt Jakob disease -
- Lived in the UK between 1980 to 1996 for 6 months or more
- Recipient of human growth hormone
- Sufferers and immediate family of sufferers of CJD
- Undiagnosed neurological disorder
- If you are a prison inmate
- Anything to do with AIDS/HIV
- Positive with disease
- Men who have had sexual relations with a man last 10 yrs
- Women who have had sex with HIV pos man and vice versa
- If you have injected drugs not prescribed
- If you have a bleeding disorder
What reasons would temporarily defer you from giving blood?
- Diarrhoea and vomiting which may be indicative of Yersinia
- Recent tattoo incl. cosmetic tattoo and piercings
- Travel to areas where tropical diseases are endemic (malaria, WNV, Zika virus, other)
- Recent dental work
- Recent vaccination
- Acupuncture
- Pregnancy
- Recent major surgery or recent transfusion
What is used as a non infectious test performed on blood donors to estimate haemoglobin levels?
Fingerprick
Describe the NZ screening policies of ONE example from each of these organisms: parasitic protozoa, bacteria, viruses, and prions
Classification of Transfusion Transmissible Infections (TTI)
TTI:
Endemic in NZ
NZ screening policy
Parasitic Protozoa
- Plasmodium* species causing malaria
- Trypanosoma cruzi* causing Chagas disease
No
Screening tests are available and are performed on donors that have returned to NZ from areas where malaria infection is endemic
No test available
Bacteria
Endogenous (Yersinia spp and Treponema pallidum)
Exogenous skin contamination
Yes
Screen all donations for syphilis (Treponema pallidum)
Defer donors who have had recent diarrhoea/vomiting
Viruses
Hepatitis B and C
Yes
All donations screened
Herpes virus EBV and CMV
Yes
CMV is screened for immunocompromised patients, or leucodepleted components used.
Retroviruses HIV-1, HIV-2, HTLV
Yes
HIV1 and 2 all donations screened; HTLV screened only during the first donation
Parvovirus B19
Yes
Donation screened for immunocompromised patients
WNV
No
Screen donors returned to NZ from area where epidemic has occurred
Prions
vCJD: variant Creutzfeldt Jakob Disease
No
Donors who lived in the UK for 6 months or more from 1980 to 1996 are deferred
What are the five transfusion transmissible infections TTI that all donors must be tested for?
- Syphilis
- HBV
- HCV
- HIV
- HTLV
Immunocompromised patients require of donors to also be screened for what TTI?
CMV. Either leucodepleted or screened blood used.
Name 4 disease-causing viruses other than HBV and WNV that can be transmitted by transfusion?
- HCV 2. HIV1 3. HIV2 4. HTLV type 1
Name 2 disease-causing bacteria that can be transmitted by transfusion
T. pallidum, Yersinia enterocolitica
Malaria, Chagas disease and Parvovirus B19 are all tested if the donor has what?
travelled overseas
Why are donors who have had diarrhoea in the past month deferred?
Because donors may have diarrhoea caused by bacterial infection eg. by Yersinia enterocolitica
Transfusion of blood contaminated by yersinia is fatal; can cause sepsis
What viruses does New Zealand not test for and does a test for them exist?
West nile virus and zika virus. Tests are available
What bacteria causes the condition syphilis? Describe three clinical manifestations of syphilis.
1) primary syphilis shows as a lesion called a chancre in the genital area after sexual contact with an infected person
2) this can then proceed to secondary and tertiary syphilis characterized by neurological involvement
3) if the bacteria T.pallidum passes from mother to foetus it can cause birth defects
How long can T. pallidum (bacteria that causes syphillis) survive in refrigerated red cells?
It can survive in refrigerated stored red cells for up to 120 hours
State two reasons why it has been difficult to develop an assay to screen donors for variant Creutzfeldt Jakob Disease (vCJD) 2 marks
- Because prions do not have detectable nucleic acids NAT (nucleic acid testing) is therefore not possible.
- There is a lack of specificity between normal human prion (PrPC) and diseased prion (PrPSc) which the assay cannot detect.
Describe and justify New Zealand policy for minimizing the risk of transmitting West Nile Virus (WNV) by blood donation
– no testing therefore deferred – testing done in US and Canada.
- keeps costs down
- no point in doing a test for a disease that is not commonly seen in the population
Briefly describe the difference between serological testing and DNA / RNA testing
-
Choose from the following infections: Hepatitis B, HIV, HCV, CMV, malaria. Describe 1 current testing method for screening for your chosen infectious agent in donated blood. You may use diagrams in your answer
-
Fully describe one current testing method for detecting Human Immunodeficiency Viruses (HIV 1 and 2) in donated blood. You may use diagrams in your answer. 15 marks
-
Fill in the table
Write a short notes on the following topics. it is worth 5 Marks -Hepatitis B
- DNA virus
– Can cause chronic hepatitis and liver cancer
– HBsAg: acute hepatitis infection. Anti-HBs + HBsAg = chronic hepatitis infection. Anti-HBs by itself = past resolved infection or immunity against Hep B.
Write a short notes on the following topics. it is worth 5 Marks Hepatitis C
- anti-HCV or HCV RNA presence in plasma is diagnostic of infection
– more difficult to treat
– 85% of patients proceed to chronic infection
– also causes liver cancer
Write a short notes on the following topics. it is worth 5 Marks HIV
Retrovirus – possesses enzyme reverse transcriptase which allows it to synthesise DNA copy from RNA genome
– Infection can be via
- Infected blood or blood products
- Artificial insemination with infected semen
- Infected shared needles
- Sexual contact with inected person 5. Infected mother to unborn baby
– presence of anti-HIV or HIV genes in plasma are diagnostic of HIV infection
– after transmission, CD4 cells become infected and over time deplete in number. Without treatment the disease progresses to symptomatic HIV and AIDS disease. This is despite humoral and cell mediated immune response. AIDS patients become susceptible to opportunistic infective agents.
Write a short notes on the following topics. it is worth 5 Marks -htlv
- HTLV = Human T Lymphotropic Virus
– Causes T cell cancers
– retrovirus
– transmitted from infected blood and blood products
– blood donors only tested for virus at first donation only (as foetus is born with the virus if the mother has the virus and passes it on).
Write a short notes on the following topics. it is worth 5 Marks -CMV
- cytomegalovirus/herpes virus
– common (60% of donors) asymptomatic and can remain latent for years
– Does not cause harm in healthy individuals
– causes birth defects if passed from mother to baby
– for immunocompromised patients, CMV-negative or leucodepleted blood products are given
- reactivation of latent CMV infection occurring in immunocompromised patients causes aggressive disease with CMV infection
Write a short notes on the following topics. it is worth 5 Marks -Malaria
- Malaria is caused by 4 parasitic protozoa species
- Plasmodium falciparum
- Plasmodium vivax
- Plasmodium malariae
- Plasmodium ovale
– Transmission is via Anopheles mosquito or via infected blood products
– Screening test is done for blood donors returned to NZ from an overseas area where the disease is endemic
Write a short notes on the following topics. it is worth 5 Marks -yersinia enterocolitica
– common bacteria prevalent in NZ farmers
– causes diarrhoea and vomiting
– also causes a transient bacteraemia (organisms in blood) and are able to multiply in 4C stored blood
– will cause bacterial septic shock in blood recipient when transfused
– therefore due to this the shelf life of blood changed from 42 to 35 days
– Leucodepletion also reduces the risk as lymphocytes engulf the bacteria during the stand-down period prior to filtration
– there is no screening test available
– Donors who have had recent diarrhoea and vomiting 12 weeks prior are deferred for a month
Write a short notes on the following topics. it is worth 5 Marks -vCJD
variant Creutzfeldt Jakob disease.
- Prion accumulates in nervous tissue
– Causes neurological dysfunction/degeneration, BSE (bovine spongiform encephalitis) and rapid death
– linked to eating beef infected with the prion (mad cow disease)
– Deferral for donors who lived in the UK 6 moths or more from 1980 to 1996
– no screening test available.
Write a short notes on the following topics. it is worth 5 Marks -West Nile virus
West Nile virus
– screening test available but there is lack of demand for it because not endemic in NZ
– RNA flavivirus – infection common in birds
– transmissible via infected mosquito that has bitten an infected bird – infection in humans is rare
– infected individuals 20% develop flu-like symptoms plus encephalitis but that is rare
– transmissible via blood transfusion
– no testing most likely due to cost of running a test which would be unnecessary because virus is not well established currently in NZ, therefore deferred
– testing done in US and Canada
