Transfusion Associated Malaria Dr Prakash.I
Introduction
Special consideration
Rarity
Delay in diagnosis
Treatment
Serious complications
1st reported in 1911
In non-endemic countries - incidence is low
Canada between 1994 and 1999 -3 cases , USA between1990 and 1999 -14 cases ,UK since 1996 -2 case, OtherEuropean countries-2 cases
US- <0.3 case/million transfused blood units
Uniqueness - caused by injection of asexual forms (Trophozoite)
Trophozoite-induced malaria Vs natural infection
pre- erythrocytic schizogony - absent
short incubation period
exo-erythrocytic schizogony - not seen
relapses do not occur
radical cure is possible
In donor blood
Relapsing illness : P. vivax and P. ovale
Asymptomatic parasitemia- variable anddepends on species
P. vivax and P. ovale rarely persist > 3 years
P. falciparum rarely > 1-2 years(3 mo)
P. malariae parasites for decades
Donor-exclusion criteria's aim : balance betweenrisk of malaria and excluding uninfected donors
Drawback in prevention : screening techniquesnot satisfactory
Criteria for suitable test for screening:
large-scale use design
high sensitivity and specificity
detect all 4 species of Plasmodium
Blood film microscopy
Traditional blood film microscopy –
large manpower
high technical skill
limited sensitivity
Microscopic exam (thick blood film-4 ml): Asingle parasite equivalent to ∼10,000parasites ina 450-mL unit of blood
Antibody detection test
Antibody detection: ELISA, immunofluorescenceassay (IFA)
Malaria antibody testing :95% sensitive and 99%specific
In endemic malaria: PPV for this test is high
Malaria antibody screening
do not indicate active infection
high discarding of collected blood units (as Ab may persist for several years after infection)
Residents in malaria-endemic countries: have anti-malarial Ab-serologic tests are unhelpful forscreening donors
Donors from Endemic region: immunity tomalaria→ low levels of parasites without clinicalsymptoms, undetectable levels of parasitaemia
Antigen detection test
Antigen detection by MAB (monoclonalantibody) technique :
more sensitive
practically feasible screening test
PCR and antigen detection tests - limitedavailability
Blood transfusion recipients
Nonimmune recipient - can become rapidly fatal
Young infants in malaria endemic regions-nonimmune recipients
Clinical severity different : Endemic Vs Nonendemic
Blood products
Whole-blood and RBC concentrates -mostcommon source.
Platelets, FFP, and leukocytes may infrequentlytransmit malaria.
As few as 15 parasites (one bite): can causemalaria.
Prevention
Endemic countries: specific donor questioning considering
Seasonal variation
Geographical distribution
Antigen detection by monoclonal Ab as a routine screening procedure : in endemic countries
Anti-malarials to recipients may help to prevent transmission
Prevention largely depends on careful questioning donors
FDA recommends deferring residents
Endemic areas : 3 years
Had malaria/Chemo : 3 years (after they become asymp.)
Non endemic : 1 year after return from malarious area
In EU
Endemic area : 3 yrs
Non-endemic areas donors: 4-12 months
Some countries reject these donors(NED) for 3 yearsor permanently (if resided for >6 months in theendemic area)
Evidence based
Support for Recommendations:
97% and 99% of the reported malaria cases inU.S. and foreign civilians occur within 1 and 3years, respectively, of having been in a malariousarea
AABB: Uniform donor history questions
Travelers may donate blood 6 months after returningfrom endemic areas if they have been free of symptomsand have not taken antimalarial drugs
Persons who have had malaria or who had been takingchemoprophylaxis shall be deferred from donating bloodfor 3 years after either becoming asymptomatic orstopping therapy or chemoprophylaxis
Immigrants or visitors from endemic areas may beaccepted as donors 3 years after departure if they areasymptomatic in the interim
Donations for preparing plasma, plasma components, orderivatives devoid of intact red blood cells are exemptedfrom these restrictions