A case report of transfusion-transmitted Plasmodium malariae from an asymptomatic non-immune traveller

Optimal malarial screening strategy in Australian blood donors: A cost-effectiveness analysis

BACKGROUND AND OBJECTIVES

The risk of transfusion-transmitted malaria (TTM) infections is extremely low in Australia, and the cost-effectiveness of the current screening strategy has not been assessed. This study aims to conduct a cost-effectiveness analysis of different malaria screening strategies in blood donors as part of the risk-based decision-making framework.

MATERIALS AND METHODS

A decision tree model was developed to assess the cost-effectiveness of five alternative malaria screening strategies from a healthcare sector perspective. Screening strategies combining total or partial removal of malaria testing with different deferral periods were considered. The probabilities of developing severe and uncomplicated TTM were based on a literature review of cases in non-endemic areas since 2000. The health outcomes were quantified using disability-adjusted life years. The costs of non-returning donors due to deferral were also included. Deterministic and probabilistic sensitivity analyses were conducted to account for data uncertainty.

RESULTS

The residual risks for all strategies were so low that the costs, mortality and morbidity associated with TTM are almost negligible. The overall costs were predominantly influenced by the costs of non-returning blood donors. As a result, removal of malaria testing and applying a 28-day deferral for at-risk donors were the least costly and most cost-effective of all the options considered.

CONCLUSION

The current screening strategy for malaria in blood donors in Australia is not an efficient use of healthcare resources. Partial or total removal of malaria testing would bring significant cost savings without significantly compromising blood safety.

Fast detection and quantification of Plasmodium species infected erythrocytes in a non-endemic region by using the Sysmex XN-31 analyzer

Background

Due to increased travel from endemic countries, malaria occurs more frequently in non-endemic regions. It is a challenge for diagnostic laboratories in non-endemic countries to provide reliable results, as experience of staff is often limited to only a few cases per year. This study evaluated the diagnostic accuracy of the fully automated Sysmex XN-31 malaria analyzer in a routine diagnostic setting in a non-endemic region was evaluated.

Methods

Samples from 112 patients suspected for malaria were examined by the Sysmex XN-31 analyzer to determine the absolute count of malaria-infected red blood cells count (MI-RBC/µL). Microscopic examination of both Quantitative Buffy Coat capillary tubes and thick and thin blood films were used as reference methods. Limits of blank (LoB), detection (LoD) and quantification (LoQ) were investigated using an in vitro Plasmodium falciparum culture. Nine hundred twenty samples of patients with RBC abnormalities were included to determine which RBC abnormalities trigger indeterminate or false positive results.

Results

No false positive nor false negative results were obtained for the examined patient samples suspected for malaria. For 3% of samples an indeterminate result by the XN-31 was obtained. The Passing-Bablok regression line for diagnostic accuracy of the parasitaemia was y = 39.75 + 0.7892 × showing a positive bias of about 21% when comparing the MI-RBC results to microscopy. The LoB, LoD and LoQ were calculated to be 4.7, 5.9, and 19.0 infected RBC/μL, respectively. From the 920 abnormal RBC samples collected, 4.6% resulted in a false positive MI-RBC result and almost half of the samples produced indeterminate results. These results were related to increases in nucleated red blood cells, reticulocytes and other abnormal RBC morphologies such as sickle cells.

Conclusions

Based on the results, the XN-31 is a fast and reliable screening method in the detection and quantification of Plasmodium species in patients However, if an abnormal red blood cell morphology is present, the results of the XN-31 should be interpreted with caution as false positive results can be caused by interfering abnormal erythrocytes.

Robust inactivation of Plasmodium falciparum in red blood cell concentrates using amustaline and glutathione pathogen reduction

BACKGROUND

Plasmodium falciparum is the parasite responsible for most malaria cases globally. The risk of transfusion-transmitted malaria (TTM) is mitigated by donor deferrals and blood screening strategies, which adversely impact blood availability. Previous studies showed robust inactivation of P. falciparum using nucleic acid-targeting pathogen reduction technologies (PRT) for the treatment of plasma and platelet components or whole blood (WB). The efficacy of the amustaline-glutathione (GSH) PRT to inactivate P. falciparum is here evaluated in red blood cells (RBC), as well the impact of PRT on parasite loads, stages, and strains.

STUDY DESIGN AND METHODS

RBC units resuspended in AS-1 or AS-5 additive solutions were spiked with ring stage-infected RBC and treated with the amustaline-GSH PRT. Parasite loads and viability were measured in samples at the time of contamination, and after treatment, using serial 10-fold dilutions of the samples in RBC cultures maintained for up to 4 weeks.

RESULTS

P. falciparum viability assays allow for the detection of very low levels of parasite. Initial parasite titer was >5.2 log₁₀ /ml in AS-1/5 RBC. No infectious parasites were detected in amustaline-GSH-treated samples after 4 weeks of culture. Amustaline-GSH inactivated high parasite loads regardless of parasite stages and strains. Amustaline readily penetrates the parasite, irreversibly blocks development, and leads to parasite death and expulsion from RBC.

DISCUSSION

Amustaline-GSH PRT demonstrated robust efficacy to inactivate malaria parasites in RBC concentrates. This study completes the portfolio of studies demonstrating the efficacy of nucleic acid-targeting PRTs to mitigate TTM risks as previously reported for platelet concentrates, plasma, and WB.

Transfusion-Transmitted Malaria and Mitigation Strategies in Nonendemic Regions

Background

Malaria is a mosquito-borne infectious disease caused by protozoan parasites of the genus Plasmodium. These parasites can be transmitted by blood transfusion especially through Red Cell Blood Concentrates collected from asymptomatic and parasitemic donors. As migration of populations from endemic areas to Europe and overseas recreational travel to endemic regions increase, there is growing risk of transfusion-transmitted malaria (TTM) in nonendemic regions of the world. The present work provides an overview of the mitigation strategies in nonendemic countries and their effectiveness and discusses possible approaches to evolve the strategies in order to maintain both a safe and adequate blood supply.

Summary

The historical and current situation of malaria and TTM in Europe and on the North American continent are described. The infectivity of Plasmodium in blood components and the consequences of TTM are presented, along with the regulations and guidelines for TTM mitigation in Europe, USA, and Canada. The regulations/guidelines currently in place in Europe allow a certain amount of leeway for local policies. A questionnaire was used to survey European countries regarding their current strategies and recent TTM cases. From the questionnaire and published cases, approximately 20 cases of TTM were identified in the past 20 years in the USA and Europe. The vast majority of implicated donors have been former residents of malaria-endemic areas, particularly former residents of hyperendemic areas in Africa. The most recent TTM cases are discussed in detail to provide insight into the gaps in current strategies. The utility and uncertainties of pathogen reduction and serological and molecular testing methods are discussed.

Key Messages

Overall, the risk of transfusion-associated malaria in nonendemic countries is considered to be low and very few TTM cases occurred in these regions in the last 20 years. The questionnaire-based strategy with questions about risk in relation to malaria exposure with or without selective testing based on questioning seems to be relatively effective, although rare and sometimes fatal transmissions still occur. An outstanding question is whether in the future molecular methods may further improve the safety of blood products and help constrain the loss of donors.

Transfusion-Transmitted Malaria of Plasmodium malariae in Palermo, Sicily

Transfusion-transmitted malaria (TTM) is a rare occurrence with serious consequences for the recipient. In non-endemic areas, the incidence of transmission of malaria by transfusion is very low. We report a clinical case of transfusion-transmitted malaria due to Plasmodium malariae, which happened in a patient with acute hemorrhagic gastropathy. Case presentation: In April 2019, a 70-year-old Italian man with recurrent spiking fever for four days was diagnosed with a P. malariae infection, as confirmed using microscopy and real-time PCR. The patient had never been abroad, but about two months before, he had received a red blood cell transfusion for anemia. Regarding the donor, we revealed that they were a missionary priest who often went to tropical regions. Plasmodium spp. PCR was also used on donor blood to confirm the causal link. Discussion and Conclusions: The donations of asymptomatic blood donors who are predominantly “semi-immune” with very low parasitic loads are an issue. The main problem is related to transfusion-transmitted malaria. Our case suggests that P. malariae infections in semi-immune asymptomatic donors are a threat to transfusion safety. Currently, microscopy is considered the gold standard for the diagnosis of malaria but has limited sensitivity to detect low levels of parasitemia. Screening using serological tests and molecular tests, combined with the donor’s questionnaire, should be used to reduce the cases of TTM.

Malaria parasite species composition of Plasmodium infections among asymptomatic and symptomatic school-age children in rural and urban areas of Kinshasa, Democratic Republic of Congo

BACKGROUND

Malaria remains a major public health concern in the Democratic Republic of Congo (DRC), and school-age children are relatively neglected in malaria prevalence surveys and may constitute a significant reservoir of transmission. This study aimed to understand the burden of malaria infections in school-age children in Kinshasa/DRC.

METHODS

A total of 634 (427 asymptomatic and 207 symptomatic) blood samples collected from school-age children aged 6 to 14 years were analysed by microscopy, RDT and Nested-PCR.

RESULTS

The overall prevalence of Plasmodium spp. by microscopy, RDT and PCR was 33%, 42% and 62% among asymptomatic children and 59%, 64% and 95% in symptomatic children, respectively. The prevalence of Plasmodium falciparum, Plasmodium malariae and Plasmodium ovale spp. by PCR was 58%, 20% and 11% among asymptomatic and 93%, 13% and 16% in symptomatic children, respectively. Among P. ovale spp., P. ovale curtisi, P. ovale wallikeri and mixed P. ovale curtisi + P. ovale wallikeri accounted for 75%, 24% and 1% of infections, respectively. All Plasmodium species infections were significantly more prevalent in the rural area compared to the urban area in asymptomatic infections (p < 0.001). Living in a rural as opposed to an urban area was associated with a five-fold greater risk of asymptomatic malaria parasite carriage (p < 0.001). Amongst asymptomatic malaria parasite carriers, 43% and 16% of children harboured mixed Plasmodium with P. falciparum infections in the rural and the urban areas, respectively, whereas in symptomatic malaria infections, it was 22% and 26%, respectively. Few children carried single infections of P. malariae (2.2%) and P. ovale spp. (1.9%).

CONCLUSION

School-age children are at significant risk from both asymptomatic and symptomatic malaria infections. Continuous systematic screening and treatment of school-age children in high-transmission settings is needed.

Plasmodium malariae, current knowledge and future research opportunities on a neglected malaria parasite species

Plasmodium malariae is often reported as a benign malaria parasite. There are limited data on its biology and disease burden in sub-Saharan Africa (sSA) possibly due to the unavailability of specific and affordable tools for routine diagnosis and large epidemiology studies. In addition, P. malariae occurs at low parasite densities and in co-infections with other species, predominately P. falciparum. The paucity of data on P. malariae infections limits the capacity to accurately determine its contribution to malaria and the effect of control interventions against P. falciparum on its prevalence. Here, we summarise the current knowledge on P. malariae epidemiology in sSA - overall prevalence ranging from 0-32%, as detected by different diagnostic methods; seroprevalence ranging from 0-56% in three countries (Mozambique, Benin and Zimbabwe), and explore the future application of next-generation sequencing technologies as a tool for enriching P. malariae genomic epidemiology. This will provide insights into important adaptive mechanisms of this neglected non-falciparum species, including antimalarial drug resistance, local and regional parasite transmission patterns and genomic signatures of selection. Improved diagnosis and genomic surveillance of non-falciparum malaria parasites in Africa would be helpful in evaluating progress towards elimination of all human Plasmodium species.

Use of a NAT-based assay to improve the surveillance system and prevent transfusion-transmitted malaria in blood banks

Background

Malaria can be transmitted by blood transfusion through donations collected from asymptomatic donors. Transfusion-transmitted malaria (TTM) poses a great risk to blood services worldwide. A good screening tool for Plasmodium spp. detection in blood banks must have a high sensitivity for prevention of TTM. However, in Brazilian blood banks, screening for malaria still relies on microscopy.

Methods

In Brazil, screening for human immunodeficiency virus type 1 (HIV), RNA/DNA for hepatitis C (HCV) and hepatitis B (HBV) viruses is mandatory for every blood donation and uses nucleic acid amplification testing (NAT). The aim of this study was to evaluate the inclusion of an assay for malaria to identify Plasmodium sp. from total nucleic acid (TNA; DNA/RNA) by targeting the 18S rRNA gene of the parasite.

Results

Considering the limitations of microscopy and the wide availability of the Brazilian NAT platform in the screening of blood units for HIV, HCV, and HBV, a molecular diagnostic tool was validated for detection of Plasmodium sp. in blood banks; a pilot study showed that using this novel NAT assay could reduce the risk of TTM.

Conclusion

The prototype HIV/HCV/HBV/malaria NAT assay was effective in detecting infected candidate donors and has good prospects to be applied in routine screening for preventing TTM.

A case of Plasmodium malariae recurrence: recrudescence or reinfection?

BACKGROUND

Plasmodium malariae is the most neglected of the six human malaria species and it is still unknown which is the mechanism underlying the long latency of this Plasmodium.

CASE PRESENTATION

A case of PCR-confirmed P. malariae recurrence in a 52-year old Italian man was observed 5 months after a primary attack. In the interval between the two observed episodes of malaria the patient denied any further stay in endemic areas except for a visit to Libya, a country considered malaria-free. Genomic DNA of the P. malariae strain using five microsatellites (PM2, PM9, PM11, PM25, PM34) and the antigen marker of circumsporozoite (csp) was amplified and sequenced. Analysis of polymorphisms of the P. malariae csp central repeat region showed differences between the strains responsible of the first and second episode of malaria. A difference in the allele size was also observed for the sequence analysis of PM2 microsatellites.

CONCLUSIONS

Plasmodium malariae is a challenging human malaria parasite and even with the use of molecular techniques the pathogenesis of recurrent episodes cannot be precisely explained.

Asymptomatic Malaria Infection and Associated Factors among Blood Donors Attending Arba Minch Blood Bank, Southwest Ethiopia

Background

It is well known that malaria can be transmitted via blood transfusion. However, it is not documented in the national donor screening protocol. Magnitude of asymptomatic malaria among donors would be the key to decide on the need of donor screening. Despite this, there is lack of such data in Ethiopia. The aim of this study was thus to estimate the prevalence of asymptomatic malaria and associated factors among blood donors.

Methods

An institution based cross-sectional study was conducted in Arba Minch blood bank from February to June, 2015. Data was collected from donors who passed the clinical donor selection criteria and recruited by systematic random sampling technique. A structured questionnaire was used to capture data on socio-demographic characteristics. Giemsa stained blood films were examined for plasmodium parasites. Magnitude of asymptomatic malaria was calculated and association of factors with malaria was assessed by multivariable logistic regressions using SPSS version 20.0.

Results

A total of 416 donors participated in the study. The proportion of infected donors was 4.1% (17/416). Eight donors were infected with Plasmodium falciparum while 9 donors were infected with Plasmodium vivax. Most positive blood films (13/17) were with parasite loads ranging from 100 – 500 parasites/µl. Donors with blood group O were more susceptible to malaria parasitemia compared to all other ABO blood groups together (AOR=6.899, 95%CI=1.951–24.391, p=0.003).

Conclusion

Magnitude of malaria parasitemia in the present study was high as compared to the national malaria prevalence. Hence, in malaria endemic areas of Ethiopia, blood should be screened before donation.

A systematic review of transfusion-transmitted malaria in non-endemic areas

BACKGROUND

Transfusion-transmitted malaria (TTM) is an accidental Plasmodium infection caused by whole blood or a blood component transfusion from a malaria infected donor to a recipient. Infected blood transfusions directly release malaria parasites in the recipient's bloodstream triggering the development of high risk complications, and potentially leading to a fatal outcome especially in individuals with no previous exposure to malaria or in immuno-compromised patients. A systematic review was conducted on TTM case reports in non-endemic areas to describe the epidemiological characteristics of blood donors and recipients.

METHODS

Relevant articles were retrieved from Pubmed, EMBASE, Scopus, and LILACS. From each selected study the following data were extracted: study area, gender and age of blood donor and recipient, blood component associated with TTM, Plasmodium species, malaria diagnostic method employed, blood donor screening method, incubation period between the infected transfusion and the onset of clinical symptoms in the recipient, time elapsed between the clinical symptoms and the diagnosis of malaria, infection outcome, country of origin of the blood donor and time of the last potential malaria exposure.

RESULTS

Plasmodium species were detected in 100 TTM case reports with a different frequency: 45% Plasmodium falciparum, 30% Plasmodium malariae, 16% Plasmodium vivax, 4% Plasmodium ovale, 2% Plasmodium knowlesi, 1% mixed infection P. falciparum/P. malariae. The majority of fatal outcomes (11/45) was caused by P. falciparum whilst the other fatalities occurred in individuals infected by P. malariae (2/30) and P. ovale (1/4). However, non P. falciparum fatalities were not attributed directly to malaria. The incubation time for all Plasmodium species TTM case reports was longer than what expected in natural infections. This difference was statistically significant for P. malariae (p = 0.006). A longer incubation time in the recipient together with a chronic infection at low parasite density of the donor makes P. malariae a subtle but not negligible risk for blood safety aside from P. falciparum.

CONCLUSIONS

TTM risk needs to be taken into account in order to enhance the safety of the blood supply chain from donors to recipients by means of appropriate diagnostic tools.

Genetic diversity of three surface protein genes in Plasmodium malariae from three Asian countries

Background

Genetic diversity of the three important antigenic proteins, namely thrombospondin-related anonymous protein (TRAP), apical membrane antigen 1 (AMA1), and 6-cysteine protein (P48/45), all of which are found in various developmental stages of Plasmodium parasites is crucial for targeted vaccine development. While studies related to the genetic diversity of these proteins are available for Plasmodium falciparum and Plasmodium vivax, barely enough information exists regarding Plasmodium malariae. The present study aims to demonstrate the genetic variations existing among these three genes in P. malariae by analysing their diversity at nucleotide and protein levels.

Methods

Three surface protein genes were isolated from 45 samples collected in Thailand (N = 33), Myanmar (N = 8), and Lao PDR (N = 4), using conventional polymerase chain reaction (PCR) assay. Then, the PCR products were sequenced and analysed using BioEdit, MEGA6, and DnaSP programs.

Results

The average pairwise nucleotide diversities (π) of P. malariae trap, ama1, and p48/45 were 0.00169, 0.00413, and 0.00029, respectively. The haplotype diversities (Hd) of P. malariae trap, ama1, and p48/45 were 0.919, 0.946, and 0.130, respectively. Most of the nucleotide substitutions were non-synonymous, which indicated that the genetic variations of these genes were maintained by positive diversifying selection, thus, suggesting their role as a potential target of protective immune response. Amino acid substitutions of P. malariae TRAP, AMA1, and P48/45 could be categorized to 17, 20, and 2 unique amino-acid variants, respectively. For further vaccine development, carboxyl terminal of P48/45 would be a good candidate according to conserved amino acid at low genetic diversity (π = 0.2–0.3).

Conclusions

High mutational diversity was observed in P. malariae trap and ama1 as compared to p48/45 in P. malariae samples isolated from Thailand, Myanmar, and Lao PDR. Taken together, these results suggest that P48/45 might be a good vaccine candidate against P. malariae infection because of its sufficiently low genetic diversity and highly conserved amino acids especially on the carboxyl end.

Electronic supplementary material

The online version of this article (10.1186/s12936-018-2176-x) contains supplementary material, which is available to authorized users.

Non-imported malaria in non-endemic countries: a review of cases in Spain

Spain declared the elimination of malaria in 1964. In non-endemic areas, the overwhelming majority of malaria cases are acquired abroad, and locally acquired infections are rare events. In Spain, malaria is a statutorily notifiable disease. During these fifty years more than ten thousand malaria cases have been reported, and about 0.8% of them did not have a history of recent travel. In this report, it was carried out a review of the ways in which malaria can be transmitted in non-endemic areas and a short description of the Spanish cases, aggregated by their transmission mechanisms. Four cases contracted malaria by mosquito bites; there were two autochthonous cases and two of "airport malaria". The other 28 cases were: congenital malaria cases, transfusion-transmitted malaria, post-transplant cases, nosocomial transmission and cases in intravenous drug users. In addition, in 1971 there was an outbreak of 54 cases due to exposure to blood or blood products. So, while malaria usually is an imported disease in non-endemic areas, it should not be excluded in the differential diagnosis of persons who have fever of unknown origin, regardless of their travel history.

Post-exposure serological responses to malaria parasites in potential blood donors

Background

Cases of transfusion-transmitted malaria have been described around the world and highlighted in some studies. Semi-immune individuals are more likely to transmit malaria as they may be asymptomatic. Some countries allow blood donations only based on epidemiological criteria while others reinforce their criteria with serological tests. However, little is known about the longevity of anti-Plasmodium spp. antibodies and its meaning in blood donation. Therefore, this study aims to assess the longevity of different subclasses of anti-Plasmodium spp. antibodies in individuals with previous stays in endemic areas, as well as to assess how those antibodies are related to personal features and travel characteristics. Based on those results, the suitability of the Portuguese blood donors screening method was addressed, i.e. the method to search for an eventual risk of transfusion–transmitted malaria among the population studied.

Results

Statistical associations were found between the presence of total anti-Plasmodium spp. antibodies and some travel characteristics, namely to be born in endemic area versus non endemic and previous episodes of malaria. The intersection between seropositive results and the last year of stay in endemic areas showed a longer longevity of anti-Plasmodium spp. antibodies than previously reported. Those results represented a considerable portion of the individuals having returned from their last stay in endemic areas more than 10 years before enrolment in this study. Considering the study population as potential blood donors, serological results also indicated that if epidemiological criteria alone were applied to screen blood donors, an important percentage of seropositive individuals would be approved for blood donation. Because the nature and meaning of those antibodies in the blood donation context is still not understood, those approved individuals could represent a risk for blood transfusion safety.

Conclusions

The place of birth and past episodes of malaria seem to be related to the serological outcome. Epidemiological criteria to screen potential blood donors are insufficient to guarantee the safety of the blood, if applied alone.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1586-x) contains supplementary material, which is available to authorized users.

Targeting of blood safety measures to affected areas with ongoing local transmission of malaria

An outbreak of locally acquired Plasmodium vivax malaria in Greece started in 2009 and peaked in 2011. Targeting of blood safety measures to affected areas with ongoing transmission of malaria raised questions of how to define spatial boundaries of such an area and when to trigger any specific blood safety measures, including whether and which blood donation screening strategy to apply. To provide scientific advice the European Centre for Disease Prevention and Control (ECDC) organised expert meetings in 2013. The outcomes of these consultations are expert opinions covering spatial targeting of blood safety measures to affected areas with ongoing local transmission of malaria and blood donation screening strategy for evidence of malaria infection in these areas. Opinions could help EU national blood safety authorities in developing a preventive strategy during malaria outbreaks.

Still Searching for a Suitable Molecular Test to Detect Hidden Plasmodium Infection: A Proposal for Blood Donor Screening in Brazil

Background

Efforts have been made to establish sensitive diagnostic tools for malaria screening in blood banks in order to detect malaria asymptomatic carriers. Microscopy, the malaria reference test in Brazil, is time consuming and its sensitivity depends on microscopist experience. Although molecular tools are available, some aspects need to be considered for large-scale screening: accuracy and robustness for detecting low parasitemia, affordability for application to large number of samples and flexibility to perform on individual or pooled samples.

Methodology

In this retrospective study, we evaluated four molecular assays for detection of malaria parasites in a set of 56 samples previously evaluated by expert microscopy. In addition, we evaluated the effect of pooling samples on the sensitivity and specificity of the molecular assays. A well-characterized cultured sample with 1 parasite/μL was included in all the tests evaluated. DNA was extracted with QIAamp DNA Blood Mini Kit and eluted in 50 μL to concentrate the DNA. Pools were assembled with 10 samples each. Molecular protocols targeting 18S rRNA, included one qPCR genus specific (Lima-genus), one duplex qPCR genus/Pf (PET-genus, PET-Pf) and one duplex qPCR specie-specific (Rougemont: Roug-Pf/Pv and Roug-Pm/Po). Additionally a nested PCR protocol specie-specific was used (Snou-Pf, Snou-Pv, Snou-Pm and Snou-Po).

Results

The limit of detection was 3.5 p/μL and 0.35p/μl for the PET-genus and Lima-genus assays, respectively. Considering the positive (n = 13) and negative (n = 39) unpooled individual samples according to microscopy, the sensitivity of the two genus qPCR assays was 76.9% (Lima-genus) and 72.7% (PET-genus). The Lima-genus and PET-genus showed both sensitivity of 86.7% in the pooled samples. The genus protocols yielded similar results (Kappa value of 1.000) in both individual and pooled samples.

Conclusions

Efforts should be made to improve performance of molecular tests to enable the detection of low-density parasitemia if these tests are to be utilized for blood transfusion screening.

Immunoregulation in human malaria: the challenge of understanding asymptomatic infection

Asymptomatic Plasmodium infection carriers represent a major threat to malaria control worldwide as they are silent natural reservoirs and do not seek medical care. There are no standard criteria for asymptomaticPlasmodium infection; therefore, its diagnosis relies on the presence of the parasite during a specific period of symptomless infection. The antiparasitic immune response can result in reducedPlasmodium sp. load with control of disease manifestations, which leads to asymptomatic infection. Both the innate and adaptive immune responses seem to play major roles in asymptomatic Plasmodiuminfection; T regulatory cell activity (through the production of interleukin-10 and transforming growth factor-β) and B-cells (with a broad antibody response) both play prominent roles. Furthermore, molecules involved in the haem detoxification pathway (such as haptoglobin and haeme oxygenase-1) and iron metabolism (ferritin and activated c-Jun N-terminal kinase) have emerged in recent years as potential biomarkers and thus are helping to unravel the immune response underlying asymptomatic Plasmodium infection. The acquisition of large data sets and the use of robust statistical tools, including network analysis, associated with well-designed malaria studies will likely help elucidate the immune mechanisms responsible for asymptomatic infection.

Malaria and blood transfusion: major issues of blood safety in malaria-endemic countries and strategies for mitigating the risk of Plasmodium parasites

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.

The Epidemiology of Imported Malaria and Transfusion Policy in 5 Nonendemic Countries

Addressing risk of imported malaria is complicated by 5 human species of Plasmodium, semi-immunity in donors with long-term exposure, increasing travel and immigration, changing risk in endemic areas, and limitations of screening assays. To gain insight into policy formulation, we have compiled epidemiologic data from 5 countries with different policies involving either deferral (the United States and Canada) or selective testing (France, England, and Australia). The greatest risk is from semi-immune former residents of endemic areas, but the greatest impact on sufficiency (donor loss) is from low-risk short-term travel. France and the UK have the highest rates of travel to Africa where most malaria cases originate. The UK has substantial travel to the Indian subcontinent where Plasmodium vivax cases are more common, and Australia, to Southeast Asia and Papua New Guinea. In the United States and Canada, malaria risk travel is more often to lower risk areas such as Mexico and the Caribbean. Each country has imported cases, predominantly Plasmodium falciparum and P. vivax, although data are incomplete. Transfusion-transmitted malaria has been rare over the last 10 years, generally involving P. falciparum, but there were 2 US cases of Plasmodium malariae. Uncertainty due to limitations of epidemiologic data and reliance on donors' answers underpins much of the complexity of policy formulation. Variability in policies between countries reflects not only epidemiologic differences but also operational considerations, donor demographics, regulatory approaches, and public pressure to react to rare transfusion-transmitted malaria cases. Testing reduces the operational impact of addressing the very small risk from travelers and offers improvement over deferral by testing all former residents of endemic areas. Notwithstanding current international regulatory requirements, policies have "evolved" through a series of additions and revisions as concerns and issues arose, with resultant variability in donor selection criteria.

The duration of Plasmodium falciparum infections

Plasmodium vivax and Plasmodium ovale are often considered the malaria parasites best adapted to long-term survival in the human host because of their latent exo-erythrocytic forms. The prevailing opinion until the middle of the last century was that the maximum duration of Plasmodium falciparum infections was less than two years. Case reports and series investigating blood donors following accidental malaria infection of blood transfusion recipients and other sporadic malaria cases in non-endemic countries have shown clearly that asymptomatic P. falciparum infections may persist for up to a decade or longer (maximum confirmed 13 years). Current policies in malaria-free countries of excluding blood donors who have lived in malarious areas are justified. Vigilance for longer than three years after declaring elimination in an area may be needed.

Perioperative considerations of the patient with malaria

Purpose

Malaria is a life-threatening infectious disease caused by the Plasmodium parasite. Increased global travel has resulted in an escalation in the number of imported cases seen in developed countries. Patients with malaria may present for surgery in both endemic and non-endemic countries. This article reviews the perioperative considerations when managing patients with malaria.

Source

A literature review of anesthesia, perioperative care, and malaria-related articles was performed using the MEDLINE^®, EMBASE™, and Web of Science databases to identify relevant articles published in English during 1945-2014. Of the 303 articles matching the search criteria, 265 were excluded based on title and abstract. Eleven of the remaining 38 articles were relevant to anesthesia/perioperative care, and 27 articles were identified as having direct relevance to critical care medicine.

Principal findings

The majority of imported malaria cases are caused by the falciparum species, which is associated with the greatest degree of morbidity and mortality. Various organ systems may be impacted as a consequence of changes in the structure and function of parasitized erythrocytes. Preoperative assessment should focus on establishing the species of malaria, the severity of disease, assessing the degree of end-organ impairment, and initiating treatment of malaria prior to surgery. Intravenous artesunate is the treatment of choice for severe falciparum malaria. Quinine is a second-line agent but has a narrow therapeutic index and particularly hazardous side effects. Intraoperatively, attention should focus on fluid management, dynamics of cerebral blood flow, and avoidance of hypoglycemia. Postoperative care of severe cases should ideally take place in a critical care unit as there may be ongoing requirements for multi-organ support, including renal replacement therapy, ventilation, and/or inotropic support. The safety of neuraxial anesthesia has not been well studied in the setting of malaria.

Conclusions

Malaria remains one of the most devastating infectious diseases worldwide. Multiple organ systems can be impacted as a consequence of changes in structure and function of parasitized erythrocytes. Safe perioperative management requires a sound knowledge of all these potential system effects.

Tropical infection after a case of total hip arthroplasty

In non-endemic areas, malaria is mainly an imported disease. This article reports a case of transfusion-related Plasmodium falciparum malaria in a non-endemic area. Despite initial clinical signs consistent with malaria, the diagnosis was not elicited because of the absence of any identified epidemiological risk factors. The case indicates that transfusion-transmitted malaria still occurs in non-endemic countries. The role of laboratory testing to prevent and diagnose transfusion-transmitted malaria in non-endemic malaria countries is crucial.