The Current Status and Potential Role of Laboratory Testing to Prevent Transfusion-Transmitted Malaria
Australian Red Cross, Melbourne, Victoria, AustraliaTransfusion Medicine Reviews (Impact Factor: 2.92). 08/2005; 19(3):229-40. DOI: 10.1016/j.tmrv.2005.02.004
Malaria remains a rare but serious complication of transfusion because of the asymptomatic persistence of parasites in some donors. In nonendemic countries, the predominant strategy of deferral or cellular component discard from "risk" donors is effective in minimizing the incidence but is wasteful. In endemic countries where recipients are commonly immune, transfusion strategies focus on chemoprophylaxis for the donor and recipient or ensure that blood collected in highly endemic regions is not transfused to patients from areas of low endemicity. Donors implicated in transfusion-transmitted malaria are predominantly "semi-immune" with very low parasite loads. Their detection by even the most sensitive antigen or polymerase chain reaction (PCR) assays cannot be guaranteed and, in a number of cases, is unlikely because the infectious dose is estimated to be 1 to 10 parasites in a unit of blood. Retrospective analysis of implicated donors has confirmed the presence of high titer antibodies in such individuals. In regions of low immunity, serological assays offer an efficient method to identify such infectious donors. The recent development of enzyme immunoassays (EIAs) with improved sensitivity to Plasmodium falciparum and Plasmodium vivax , the predominant transfusion threats, has heightened the appeal of serological testing. Although universal serological screening in nonendemic regions is not cost-effective, targeted screening of donors identified at risk by travel-based questioning can significantly reduce wastage through reinstatement. Importantly, transfusion safety does not appear to be compromised by this approach as evidenced by the lack of a documented transmission in France between 1983 and September 2002, where such a strategy has been used since 1976. The development of automated protein microarray-based technology has the potential to further enhance antibody/antigen sensitivity; however, its application to donor screening is likely to be some years off. There is also the potential that pathogen inactivation techniques currently under development to address the bacterial contamination of blood components may also be effective against malaria parasites to make malarial testing redundant or at least reduce its cost/benefit ratio. Nonetheless, there are still significant problems to be solved in respect of validating and licensing these systems. Assuming that they are successfully marketed, their high cost may also impact their cost-effectiveness in comparison with targeted malaria testing strategies already in place in some jurisdictions.
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- "The whole blood and red blood cell (RBC) units are the primary carriers of TTM, though platelets and leukocytes may contain variable numbers of RBCs and have seldom transmitted malaria (Dover and Guinee 1971; Garfield et al. 1978; Wylie 1993). Malarial parasites can survive in donated blood between 2 and 6 °C for until 3 weeks (Chattopadhyay et al. 2010; Seed et al. 2005; Grant et al. 1960). The health problems posed by TTM are immense, especially when the blood donation is obtained without proper blood management strategies (Ali et al. 2004). "
ABSTRACT: Malaria inflicts humankind over centuries, and it remains as a major threat to both clinical medicine and public health worldwide. Though hemotherapy is a life-sustaining modality, it continues to be a possible source of disease transmission. Hence, hemovigilance is a matter of grave concern in the malaria-prone third-world countries. In order to pursue an effective research on hemovigilance, a comprehensive search has been conducted by using the premier academic-scientific databases, WHO documents, and English-language search engines. One hundred two appropriate articles were chosen for data extraction, with a particular reference to emerging pathogens transmitted through blood transfusion, specifically malaria. Blood donation screening is done through microscopic examination and immunological assays to improve the safety of blood products by detection major blood-borne pathogens, viz., HIV, HBV, HCV, syphilis, and malarial parasites. Transfusion therapy significantly dwindles the preventable morbidity and mortality attributed to various illnesses and diseases, particularly AIDS, tuberculosis, and malaria. Examination of thick and thin blood smears are performed to detect positivity and to identify the Plasmodium species, respectively. However, all of these existing diagnostic tools have their own limitations in terms of sensitivity, specificity, cost-effectiveness, and lack of resources and skilled personnel. Globally, despite the mandate need of screening blood and its components according to the blood-establishment protocols, it is seldom practiced in the low-income/poverty-stricken settings. In addition, each and every single phase of transfusion chain carries sizable inherent risks from donors to recipients. Interestingly, opportunities also lie ahead to enhance the safety of blood-supply chain and patients. It can be achieved through sustainable blood-management strategies like (1) appropriate usage of precise diagnostic tools/techniques, (2) promoting hemovigilance system, and (3) adopting novel processes of inactivation technology. Furthermore, selection of the zero-risk donors could pave the way to build a transmissible malaria-free world in the near future.
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- "have implemented malaria antibody screening such that only individuals who are known to have been exposed to organisms causing malaria are subject to deferral of donations rather than all donors who have traveled to or lived in regions where malaria is endemic. Commercial antibody enzyme-linked immunosorbent assays (ELISAs) are currently in use in some countries like the United Kingdom, France, and Australia, and reinstatement of questionnairedeferred donors was discussed in Canada and the United States   . In these cases, blood donors are tested for antibodies directed against Plasmodium-derived antigens within several months of deferral; when the tested individuals show negative antibody results, donation is allowed. "
ABSTRACT: Background: Rapid diagnostic tests for malaria are now a commonly used procedure for malaria diagnosis. Despite some problems related to sensitivity and applicability, malaria rapid diagnostic tests (RDTs), are currently considered the best option to overcome well trained experts in blood banks and fast releas of blood units. Objectives: To detect malarial parasites using OptiMAL IT rapid test and to compare this method with the peripheral blood smear (PBS) and polymerase chain reaction (PCR) methods. Methods: Blood samples were collected from 100 patients clinically confirmed of having malaria and from 6698 random healthy blood donor volunteers. These samples were used to perform PBS examination, the OptiMAL test and PCR by standard protocols. Results: PBS examination found malarial parasites in 100 (100%) patients samples with a parasite load more than 0.01% and negative for all samples of blood donor volunteers. Positive samples obtained in PBS were also positive by OptiMAL test without differentiating between mixed infection. PCR could detect P. falciparum in 100 (100%) patients samples and two (2%) were positive for P. vivax in addition to P. falciparum. Conclusions: OptiMAL IT rapid diagnostic test can replace the peripheral blood smear method in blood banks with taking into consideration the limit of kit parasite load detectability. PCR is the most sensitive method that can detect low parasitaemia and mixed infection.
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- "Immunofluorescence detection of malaria antibodies was until recently the gold standard , but is unsuitable for high-throughput screening. ELISA-based seroprevalence screening is a potentially useful epidemiological tool . An immuno-enzymatic assay combining the crude P. falciparum antigen and recombinant P. vivax proteins was already developed, exhibiting high specificity and analytical sensitivity (96.7 and 93.1%, respectively) in the detection of Plasmodium antibodies . "
ABSTRACT: Background Malaria Is A Life-Threatening Pathology In Africa. Plasmodium Falciparum And Plasmodium Vivax Attract The Most Focus Because Of Their High Prevalence And Mortality. Knowledge About The Prevalence Of The Cryptic Pathogens Plasmodium Ovale And Plasmodium Malariae Is Limited. Thanks To Recombinant Tools, Their Seroprevalence Was Measured For The First Time, As Well As The Prevalence Of Mixed Infections In A Malaria-Asymptomatic Population In Benin, A Malaria-Endemic Country. Methods A Panel Of 1,235 Blood Donations Collected Over Ten Months In Benin Was Used For Validation Of The Recombinant Tools. Recombinant P. Falciparum, P. Malariae, P. Ovale MSP1, And P. Falciparum AMA1 Were Engineered And Validated On A Biobank With Malaria-Infected Patients (N = 144) Using A Species-Speific ELISA Test (Recelisa). Results Were Compared To An ELISA Using A Native P. Falciparum Antigen (NatELISA). Results Among Microscopically Negative African Blood Donors, 85% (1,050/1,235) Present Antibodies Directed To Native P. Falciparum, 94.4% (1,166/1,235) To rPfMSP1 And rPfAMA1, 56.8% (702/1,235) To rPoMSP1, 67.5% (834/1235) To rPmMSP1 And 45.3% Of The Malaria Seropositive Population Had Antibodies Recognizing The Three Species. Conclusion A High Rate Of Antibodies Against P. Ovale And P. Malariae Was Found In Asymptomatic Blood Donors. The Proportion Of Mixed Infections Involving Three Species Was Also Unexpected. These Data Suggest That Determining Seroprevalence For These Cryptic Species Is An Appropriate Tool To Estimate Their Incidence, At The Eve Of Upcoming Anti-P. Falciparum Vaccination Campaigns.
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