Transfusion-Transmitted Malaria in Sub-Saharan Africa
Transfusion-Transmitted Malaria in Sub-Saharan Africa
Malaria is a protozoan parasitic infection of humans resulting from one or more of the five species of the genus Plasmodium (Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium knowlesi). It is one of the most important parasitic diseases in the world and remains a major challenge to mankind. Malaria can be efficiently transmitted by transfusion of cellular blood components and it is undoubtedly responsible for the majority of transfusion-transmitted diseases in the world. But, mainly due to the high interest in human immunodeficiency virus blood safety, transfusion transmission of malaria has been a neglected topic until recently. As a result, there has been a paucity of information concerning the distribution and potential role of the different Plasmodium species in transfusion-related malaria cases, and the clinical impact of parasitaemic blood in recipients, particularly young children and pregnant women who are the highest consumers of blood transfusions in sub-Saharan Africa (SSA). When malaria is transmitted through blood transfusion to a non-immune recipient, it can progress rapidly and may lead to significant morbidity and mortality, specifically when diagnosis is delayed.
The incidence of transfusion-transmitted malaria (TTM) among people residing in endemic areas is unknown. As a matter of fact, a substantial proportion of the population in malaria-endemic countries has asymptomatic parasitaemia, making it difficult to be sure whether malaria occurring after blood transfusion was acquired from the transfusion or not. Nonetheless, the World Health Organization (WHO) recommends that all blood donations should be screened for malaria where "appropriate and possible", and that there should be quality assured testing for transfusion-transmitted infections (TTIs). These recommendations have significant resource implications and have not been widely implemented by transfusion services in SSA. Indeed, there are reasons for the difficulty in screening blood for malaria in SSA. Severe blood shortages are widespread and would be exacerbated by rejecting blood that contains malaria parasites. More so, there is currently no assay to screen blood with low-levels of parasites that is sensitive, practical and affordable enough for use by transfusion services in endemic countries. Hence, there is no evidence-based guidance to indicate which malaria screening methods are effective for use by transfusion services in malaria-endemic countries or what action should be undertaken if the donated blood tests positive.
Other transfusion guidelines suggest that transfusion recipients should be given systematic anti-malarial prophylaxis. For many years, presumptive anti-malarial treatment with inexpensive chloroquine was given to blood recipients to prevent TTM. However, the spread of chloroquine resistance across SSA has led to such a strategy becoming redundant and ineffective. Alternatives to chloroquine, such as artemisinin and artemisinin-based combination therapy (ACT) are considerably more expensive, weakening the applicability and usefulness of anti-malarial prophylaxis in resource-poor settings until latterly.
Fortunately, a new programme, the Affordable Medicines Facility - Malaria (AMFm), has recently been put in place with satisfactory results. This is a pilot supra-national subsidy programme that aims to increase access and affordability, therefore, reducing the price of ACT to levels similar to that of less effective anti-malarials (such as sulphadoxine-pyrimethamine and chloroquine). The evaluation of this programme shows that there is an increased availability of low-priced ACT with no significant variation in availability based on remoteness. Its implementation in SSA could thereby reinforce the use of ACT for systematic prophylaxis of blood recipients in order to efficiently prevent TTM as well as an unnecessary wastage of blood units, even in remote areas. The present review aims to highlight the burden of TTM in SSA, and discusses the strategies for the prevention of TTM in these countries.
Background
Malaria is a protozoan parasitic infection of humans resulting from one or more of the five species of the genus Plasmodium (Plasmodium falciparum, Plasmodium vivax, Plasmodium ovale, Plasmodium malariae and Plasmodium knowlesi). It is one of the most important parasitic diseases in the world and remains a major challenge to mankind. Malaria can be efficiently transmitted by transfusion of cellular blood components and it is undoubtedly responsible for the majority of transfusion-transmitted diseases in the world. But, mainly due to the high interest in human immunodeficiency virus blood safety, transfusion transmission of malaria has been a neglected topic until recently. As a result, there has been a paucity of information concerning the distribution and potential role of the different Plasmodium species in transfusion-related malaria cases, and the clinical impact of parasitaemic blood in recipients, particularly young children and pregnant women who are the highest consumers of blood transfusions in sub-Saharan Africa (SSA). When malaria is transmitted through blood transfusion to a non-immune recipient, it can progress rapidly and may lead to significant morbidity and mortality, specifically when diagnosis is delayed.
The incidence of transfusion-transmitted malaria (TTM) among people residing in endemic areas is unknown. As a matter of fact, a substantial proportion of the population in malaria-endemic countries has asymptomatic parasitaemia, making it difficult to be sure whether malaria occurring after blood transfusion was acquired from the transfusion or not. Nonetheless, the World Health Organization (WHO) recommends that all blood donations should be screened for malaria where "appropriate and possible", and that there should be quality assured testing for transfusion-transmitted infections (TTIs). These recommendations have significant resource implications and have not been widely implemented by transfusion services in SSA. Indeed, there are reasons for the difficulty in screening blood for malaria in SSA. Severe blood shortages are widespread and would be exacerbated by rejecting blood that contains malaria parasites. More so, there is currently no assay to screen blood with low-levels of parasites that is sensitive, practical and affordable enough for use by transfusion services in endemic countries. Hence, there is no evidence-based guidance to indicate which malaria screening methods are effective for use by transfusion services in malaria-endemic countries or what action should be undertaken if the donated blood tests positive.
Other transfusion guidelines suggest that transfusion recipients should be given systematic anti-malarial prophylaxis. For many years, presumptive anti-malarial treatment with inexpensive chloroquine was given to blood recipients to prevent TTM. However, the spread of chloroquine resistance across SSA has led to such a strategy becoming redundant and ineffective. Alternatives to chloroquine, such as artemisinin and artemisinin-based combination therapy (ACT) are considerably more expensive, weakening the applicability and usefulness of anti-malarial prophylaxis in resource-poor settings until latterly.
Fortunately, a new programme, the Affordable Medicines Facility - Malaria (AMFm), has recently been put in place with satisfactory results. This is a pilot supra-national subsidy programme that aims to increase access and affordability, therefore, reducing the price of ACT to levels similar to that of less effective anti-malarials (such as sulphadoxine-pyrimethamine and chloroquine). The evaluation of this programme shows that there is an increased availability of low-priced ACT with no significant variation in availability based on remoteness. Its implementation in SSA could thereby reinforce the use of ACT for systematic prophylaxis of blood recipients in order to efficiently prevent TTM as well as an unnecessary wastage of blood units, even in remote areas. The present review aims to highlight the burden of TTM in SSA, and discusses the strategies for the prevention of TTM in these countries.
