Altered Offspring Immunity in Maternal Parasitic Infections.

Maternal infection during pregnancy is known to alter the development and function of offspring's immune system, leading to inappropriate immune responses to common childhood infections and immunizations. Although this is an expanding field, maternal parasitic infections remain understudied. Millions of women of reproductive age are currently at risk for parasitic infection, whereas many pregnant, chronically infected women are excluded from mass drug administration due partially to a lack of resources, as well as fear of unknown adverse fetal developmental outcomes. In areas endemic for multiple parasitic infections, such as sub-Saharan Africa, there are increased rates of morbidity and mortality for various infections during early childhood in comparison with nonendemic areas. Despite evidence supporting similar immunomodulatory effects between various parasite species, there is no clear mechanistic understanding of how maternal infection reprograms offspring immunity. This brief review will compare the effects of selected maternal parasitic infections on offspring immunity.

Detection methods and prevalence of transmission stages of Toxoplasma gondii, Giardia duodenalis and Cryptosporidium spp. in fresh vegetables: a review.

One of the ways of human parasitic infection is the accidental ingestion of vegetables contaminated with parasites, which represents a major human health hazard. This non-exhaustive review aims to evaluate studies carried out on five types of vegetables (lettuce, parsley, coriander, carrot and radish) since 2000, particularly the methods used for recovery, concentration, detection and identification of protozoan parasites such as Toxoplasma gondii, Giardia duodenalis and Cryptosporidium spp., and the results of each work. Various studies have determined the presence of pathogenic parasites in fresh vegetables with different rates; this variation in rate depends particularly on the detection method used which is related to each parasite and each vegetable type. The variation in parasitic prevalence in food could be due to different factors such as the geographical location, the size of analysed samples and the methods used for parasite detection.

How globalization and climate change could affect foodborne parasites.

Foodborne parasites, most of which are zoonotic, represent an important human health hazard. These pathogens which include both protozoa (e.g., Cryptosporidium spp., Cyclospora cayetanensis, Toxoplasma gondii) and helminths (e.g., liver and intestinal flukes, Fasciola spp., Paragonimus spp., Echinococcus spp., Taenia spp., Angiostrongylus spp., Anisakis spp., Ascaris spp., Capillaria spp., Toxocara spp., Trichinella spp., Trichostrongylus spp.), have accompanied the human species since its origin and their spread has often increased due to their behavior. Since both domesticated and wild animals play an important role as reservoirs of these pathogens the increase/decrease of their biomasses, migration, and passive introduction by humans can change their epidemiological patterns. It follows that globalization and climate change will have a tremendous impact on these pathogens modifying their epidemiological patterns and ecosystems due to the changes of biotic and abiotic parameters. The consequences of these changes on foodborne parasites cannot be foreseen as a whole due to their complexity, but it is important that biologists, epidemiologists, physicians and veterinarians evaluate/address the problem within a one health approach. This opinion, based on the author's experience of over 40 years in the parasitology field, takes into consideration the direct and indirect effects on the transmission of foodborne parasites to humans.

Priorities in research on foodborne parasites indicated by short-term scientific missions as part of COST Action a European Network for Foodborne Parasites (Euro-FBP).

The European Cooperation in Science and Technology (COST) is a funding organization for the creation of research networks. These networks support collaboration and networking among scientists across Europe and thereby give impetus to research advancements and innovation. One of the most important mechanisms of COST actions are the short-term scientific missions (STSM), which are a funding mechanism that enables scientists, particularly those earlier in their careers, to visit an institution or laboratory in another COST Member state in order to learn techniques that will enhance their skills and improve the scientific knowledge of their institution. The European Network for Foodborne Parasites (Euro-FBP; FA1408) was a COST Action that ended in early 2019, which brought together different experts with knowledge and interest on a broad spectrum of different foodborne parasites of relevance in Europe. In the course of the Euro-FBP COST Action, 32 such STSM occurred. This article provides a short overview of the short-term scientific missions that were approved during this action, as well as the relation of these actions to several relevant socio-economic parameters. The subjects of these STSM, the majority of which were concerned with detection techniques, probably reflect the priorities for research skills on foodborne parasites in Europe.

Risk-based surveillance for meat-borne parasites.

There is a plethora of meat-borne hazards - including parasites - for which there may be a need for surveillance. However, veterinary services worldwide need to decide how to use their scarce resources and prioritise among the perceived hazards. Moreover, to remain competitive, food business operators - irrespective of whether they are farmers or abattoir operators - are preoccupied with maintaining a profit and minimizing costs. Still, customers and trade partners expect that meat products placed on the market are safe to consume and should not bear any risks of causing disease. Risk-based surveillance systems may offer a solution to this challenge by applying risk analysis principles; first to set priorities, and secondly to allocate resources effectively and efficiently. The latter is done through a focus on the cost-effectiveness ratio in sampling and prioritisation. Risk-based surveillance was originally introduced into veterinary public health in 2006. Since then, experience has been gathered, and the methodology has been further developed. Guidelines and tools have been developed, which can be used to set up appropriate surveillance programmes. In this paper, the basic principles are described, and by use of a surveillance design tool called SURVTOOLS (https://survtools.org/), examples are given covering three meat-borne parasites for which risk-based surveillance is 1) either in place in the European Union (EU) (Trichinella spp.), 2) to be officially implemented in December 2019 (Taenia saginata) or 3) only carried out by one abattoir company in the EU as there is no official EU requirement (Toxoplasma gondii). Moreover, advantages, requirements and limitations of risk-based surveillance for meat-borne parasites are discussed.

Contamination of coins and banknotes as sources of transmission of parasitic pathogens: a pilot study from Iran.

OBJECTIVE: This study was conducted to determine the presence, type, and rate of parasitic contamination in Iranian currencies. STUDY DESIGN: This was a cross-sectional study. METHODS: Coins and banknotes of different denominations were randomly collected from sellers and markets in Tabriz, Northwest of Iran, for examining parasitic contamination. RESULTS: Entamoeba coli and Giardia intestinalis were the most identified species of parasites in this study. Other parasites detected were Cryptosporidium parvum, Ascaris lumbricoides, Entamoeba histolytica, Fasciola hepatica, and Toxocara cati. A high rate of parasitic contamination was found in banknotes compared with coins, and a statistically significant association was found between parasitic contamination and the apparent condition of the currencies. The notes of lower denominations showed the highest contamination rates. The highest parasitic contamination was found in coins and banknotes obtained from public toilet services, butchers, and beggars. CONCLUSIONS: The findings emphasize the role of circulating coins and banknotes in the risk of pathogenic parasite transmission.

A Host-Parasite System with Multiple Parasite Strains and Superinfection Revisited: The Global Dynamics.

In this paper, we revisit a host-parasite system with multiple parasite strains and superinfection proposed by Nowak and May (Proc R Soc Lond B 255(1342):81-89, 1994), and study its global dynamics when we relax the two strict conditions assumed therein. As for system with two parasite strains, we derive that the basic reproduction number [Formula: see text] is the threshold condition for parasite extinction and the invasion reproduction number [Formula: see text] is the subthreshold condition for coexistence of two parasite strains. As for system with three parasite strains, we are surprised to discover the global stability of parasite-free and coexistence equilibrium, which is distinct from the previous result. Furthermore, for system with n strains, we obtain the global asymptotical stability of the parasite-free equilibrium, conjecture a general result on the global stability of coexistence equilibrium and provide two numerical examples to testify our conjecture.

Current Status of Parasite Infections in Indonesia: A Literature Review.

Indonesia and South Korea have become inseparable in various respects since the 2 countries established diplomatic relation in 1973. Indonesia is a tropical region that stretches across the equator, comprised of 5 main islands (Java, Kalimantan, Sumatra, Sulawesi, and Papua) and 4 archipelagoes (Riau, Bangka Belitung, Nusa Tenggara, and Maluku). As most population of Eastern Indonesia (Sulawesi, Papua and Nusa Tenggara & Maluku) live in poor areas, it is expected that there will be many parasites. Nevertheless, little is known about the status of parasites in Indonesia. This study examines the prevalences of malaria and lymphatic filaria, which are prevalent in Indonesia, as well as those of soil-transmitted-helminths (STH). As a result, the Plasmodium falciparum and P. vivax case loads are almost equal. The current prevalence of P. vivax is uniformly low (<5%) in all age groups and annual parasite incidence (API) showed decreasing tendency as 0.84 per 1,000 population in 2016. However, more than 65 million people still live in malaria epidemic regions. Lymphatic filariasis remains an important public health problem and 236 cities were classified as endemic areas in 514 cities/districts in 2017. It is difficult to ascertain the current prevalence rate of STH in Indonesia, although West Sumba and Southwest Sumba in East Nusa Tenggara reported prevalence rate of more than 20%. The study also considers the (sero) prevalences of other parasites identified in Indonesia. This report should be useful not only to parasitologists but also to travelers and people with business in Indonesia.

Evidence for Previously Unidentified Sexual Transmission of Protozoan Parasites.

Knowing the mode of transmission of a disease can affect its control and prevention. Here, we identify 5 protozoan parasites with demonstrated presence in seminal fluid, only 1 of which has been identified as a sexually transmitted disease among humans.

Recent epidemiology of sexually transmissible enteric infections in men who have sex with men.

PURPOSE OF REVIEW: Sexual transmission of enteric pathogens in men who have sex with men (MSM) has been described since the 1970s. Recently, an increasing number of enteric infection outbreaks have been reported in MSM. This article summarizes recent outbreaks and discusses the key issues for prevention and control. RECENT FINDINGS: Sexually transmissible enteric infections (STEIs) can spread rapidly and internationally within highly connected MSM populations and are often associated with antimicrobial resistance (AMR). The infections often cluster in high-risk groups of HIV-positive MSM who are more likely to engage in diverse sexual practices and chemsex, and to have multiple other sexually transmitted infections (STIs). SUMMARY: The roles of asymptomatic and/or persistent infection and other contextual factors in STEI transmission are not well described. STEI-associated AMR is increasing and has potential to spread rapidly in MSM, warranting further public health attention. A better understanding of the factors associated with sexual transmission will enable the development of more effective control measures. A holistic approach that promotes health and wellbeing as well as infection prevention and management is needed.

Two different strategies of host manipulation allow parasites to persist in intermediate-definitive host systems.

Trophically transmitted parasites start their development in an intermediate host, before they finish the development in their definitive host when the definitive host preys on the intermediate host. In intermediate-definitive host systems, two strategies of host manipulation have been evolved: increasing the rate of transmission to the definitive host by increasing the chance that the definitive host will prey on the intermediate host, or increasing the lifespan of the parasite in the intermediate host by decreasing the predation chance when the intermediate host is not yet infectious. As the second strategy is less well studied than the first, it is unknown under what conditions each of these strategies is prevailed and evolved. We analysed the effect of both strategies on the presence of parasites in intermediate-definitive host systems with a structured population model. We show that the parasite can increase the parameter space where it can persist in the intermediate-definitive host system using one of these two strategies of host manipulation. We found that when the intermediate host or the definitive host has life-history traits that allow the definitive host to reach large population densities, that is high reproduction rate of the intermediate host or high conversion efficiency of the definitive host (efficiency at which the uninfected definitive host converts caught intermediate hosts into offspring), respectively, evolving manipulation to decrease the predation chance of the intermediate host will be more beneficial than manipulation to increase the predation chance to enhance transmission. Furthermore, manipulation to decrease the predation chance of the intermediate host results in higher population densities of infected intermediate hosts than manipulation that increases the predation chance to enhance transmission. Our study shows that host manipulation in early stages of the parasite development to decrease predation might be a more frequently evolved way of host manipulation than is currently assumed.

Interactions between host sex and age of exposure modify the virulence-transmission trade-off.

The patterns of immunity conferred by host sex or age represent two sources of host heterogeneity that can potentially shape the evolutionary trajectory of disease. With each host sex or age encountered, a pathogen's optimal exploitative strategy may change, leading to considerable variation in expression of pathogen transmission and virulence. To date, these host characteristics have been studied in the context of host fitness alone, overlooking the effects of host sex and age on the fundamental virulence-transmission trade-off faced by pathogens. Here, we explicitly address the interaction of these characteristics and find that host sex and age at exposure to a pathogen affect age-specific patterns of mortality and the balance between pathogen transmission and virulence. When infecting age-structured male and female Daphnia magna with different genotypes of Pasteuria ramosa, we found that infection increased mortality rates across all age classes for females, whereas mortality only increased in the earliest age class for males. Female hosts allowed a variety of trade-offs between transmission and virulence to arise with each age and pathogen genotype. In contrast, this variation was dampened in males, with pathogens exhibiting declines in both virulence and transmission with increasing host age. Our results suggest that differences in exploitation potential of males and females to a pathogen can interact with host age to allow different virulence strategies to coexist, and illustrate the potential for these widespread sources of host heterogeneity to direct the evolution of disease in natural populations.

Tolerance of infection: A role for animal behavior, potential immune mechanisms, and consequences for parasite transmission.

Infected organisms can resist or tolerate infection, with tolerance of infection defined as minimizing per-parasite reductions in fitness. Although tolerance is well studied in plants, researchers have only begun to probe the mechanisms and transmission consequences of tolerance in animals. Here we suggest that research on tolerance in animals would benefit from explicitly incorporating behavior as a component of tolerance, given the importance of behavior for host fitness and parasite transmission. We propose two distinct manifestations of tolerance in animals: tissue-specific tolerance, which minimizes fitness losses due to tissue damage during infection, and behavioral tolerance, which minimizes fitness losses by maintaining normal, fitness-enhancing behaviors during infection. Here we briefly review one set of potential immune mechanisms underlying both responses in vertebrate animals: inflammation and its associated signaling molecules. Inflammatory responses, including broadly effective resistance mechanisms like the production of reactive oxygen species, can incur severe costs in terms of damage to a host's own tissues, thereby reducing tissue-specific tolerance. In addition, signaling molecules involved in these responses facilitate stereotypical behavioral changes during infection, which include lethargy and anorexia, reducing normal behaviors and behavioral tolerance. We consider how tissue-specific and behavioral tolerance may vary independently or in conjunction and outline potential consequences of such covariation for the transmission of infectious diseases. We put forward the distinction between tissue-specific and behavioral tolerance not as a definitive framework, but to help stimulate and broaden future research by considering animal behavior as intimately linked to the mechanisms and consequences of tolerance in animals.

Parasites as drivers of key processes in aquatic ecosystems: Facts and future directions.

Despite the advances in our understanding of the ecological importance of parasites that we have made in recent years, we are still far away from having a complete picture of the ecological implications connected to parasitism. In the present paper we highlight key issues that illustrate (1) important contributions of parasites to biodiversity, (2) their integral role in ecosystems, (3) as well as their ecological effects as keystone species (4) and in biological invasion processes. By using selected examples from aquatic ecosystems we want to provide an insight and generate interest into the topic, and want to show directions for future research in the field of ecological parasitology. This may help to convince more parasitologists and ecologists contributing and advancing our understanding of the complex and fascinating interplay of parasites, hosts and ecosystems.

Competence of hosts and complex foraging behavior are two cornerstones in the dynamics of trophically transmitted parasites.

Multi-host trophically transmitted parasite (TTP) is a common life cycle where prey and predators are respectively intermediate and definitive hosts of the parasite. In these systems, the foraging response of the predator toward variations in prey community composition underlies the dynamic of the parasite. Therefore, modeling epidemiological dynamic of infectious diseases considering ecological predator-prey interactions is essential to understand the spreading of parasites in ecosystems. However, two important weaknesses of previous TTP models including feeding interaction can be pointed out: (i) the choice of a linear density-dependent contact rate is faintly realistic as it supposes an unlimited ingestion rate with an increase of prey density and (ii) considering only one host prey species prevents the study of host biodiversity effect due to change in the prey community composition where species have different competences to be infected and to transmit the parasite. This article attempts to address the dynamics of parasite in a context of multiple intermediate hosts differentiated by their competences and of complex foraging behavior of the predator. We present and analyze a deterministic one predator-two prey model, which is then used to explore the transmission cycle of the cestode Echinococcus multilocularis. This study examines the foraging condition for the co-existence of the prey, and then, based on the computation of the threshold measure of disease risk, R0, we show that the pattern of feeding interactions changes the relationship between disease risk and prey community composition. Finally, we disentangle the mechanism leading to the counter-intuitive observation of a decrease of disease risk while the population density of intermediate hosts increases.

Digging for answers: contributions of density- and frequency-dependent factors on ectoparasite burden in a social mammal.

Due to the density-dependent nature of parasite transmission parasites are generally assumed to constrain the evolution of sociality. However, evidence for a correlation between group size and parasite burden is equivocal, particularly for mammals. Host contact rates may be modified by mobility of the host and parasite as well as social barriers. In the current study, we used the common mole-rat (Cryptomys hottentotus hottentotus), a social subterranean rodent, as a model system to investigate the effect of host density and frequency of contact rates on ectoparasite burdens. To address these factors we used a study species that naturally varies in population densities and intergroup contact rates across its geographic range. We found that ectoparasite prevalence, abundance and species richness decreased with increasing host density at a regional scale. At the same time, measures of parasite burden increased with intergroup contact rates. Ectoparasite burdens decreased with colony size at the group level possibly as a result of increased grooming rates. Equating group size with population density might be too simplistic an approach when assessing parasite distributions in social mammals. Our data suggest that frequency-dependent mechanisms may play a much greater role at a population level than density-dependent mechanisms in determining parasite distributions in social species. We suggest that future studies should explicitly consider behavioural mechanisms that may affect parasite distribution.

Application of GIS technology in public health: successes and challenges.

The uptake and acceptance of Geographic Information Systems (GIS) technology has increased since the early 1990s and public health applications are rapidly expanding. In this paper, we summarize the common uses of GIS technology in the public health sector, emphasizing applications related to mapping and understanding of parasitic diseases. We also present some of the success stories, and discuss the challenges that still prevent a full scope application of GIS technology in the public health context. Geographical analysis has allowed researchers to interlink health, population and environmental data, thus enabling them to evaluate and quantify relationships between health-related variables and environmental risk factors at different geographical scales. The ability to access, share and utilize satellite and remote-sensing data has made possible even wider understanding of disease processes and of their links to the environment, an important consideration in the study of parasitic diseases. For example, disease prevention and control strategies resulting from investigations conducted in a GIS environment have been applied in many areas, particularly in Africa. However, there remain several challenges to a more widespread use of GIS technology, such as: limited access to GIS infrastructure, inadequate technical and analytical skills, and uneven data availability. Opportunities exist for international collaboration to address these limitations through knowledge sharing and governance.

Human and animal health surveys among pastoralists.

Valid human and livestock health surveys, including longitudinal follow-up, are feasible among mobile pastoralists and provide fundamental information to agencies for interventions that are responsive to realities and effective in addressing the needs of pastoralists. However, pastoralists are often excluded from studies, surveillance systems and health programmes. The occurrence of preventable and treatable diseases such as perinatal tetanus, measles and tuberculosis are indicative of limited access to health providers and information. It is difficult for health services to include effective outreach with their available financial and human resources. One consequence is that maternal mortality rates among pastoralists are unacceptably high. Environmental determinants such as the quality of water and the pasture ecosystems further influence the morbidity of pastoralists. In the Sahel, the nutritional status of pastoralist children is seasonally better than that of settled children; but pastoralist women tend to have higher acute malnutrition rates. Pastoralist women are more vulnerable than men to exclusion from health services for different context-specific reasons. Evidence-based control measures can be assessed in cluster surveys with simultaneous assessments of health among people and livestock, where data on costs of disease and interventions are also collected. These provide important arguments for governmental and non-governmental agencies for intervention development. New, integrated One Health surveillance systems making use of mobile technology and taking into account local concepts and the experiences and priorities of pastoralist communities, combined with sound field data, are essential to develop and provide adapted human and animal health services that are inclusive for mobile pastoralist communities and allow them to maintain their mobile way of life.

Il est possible de réaliser auprès des populations de pasteurs nomades des enquêtes sérieuses sur la santé des personnes et des troupeaux assorties d'études de suivi longitudinales, et de fournir ainsi aux organisations pertinentes des informations fondamentales pour la conception d'interventions adaptées à la situation réelle des pasteurs et répondant à leurs besoins. Or, les populations pastorales sont fréquemment exclues des études, des systèmes de surveillance et des programmes sanitaires. L'incidence de maladies évitables et traitables, par exemple le tétanos néonatal, la rougeole et la tuberculose dénote un accès limité à l'information et aux prestations de santé. Avec les ressources financières et humaines dont ils disposent, les services de santé ne parviennent pas à assurer une couverture efficace de ces populations. L'une des conséquences de cet état de fait est le taux de mortalité maternelle intolérablement élevé enregistré dans les communautés pastorales. Certains déterminants environnementaux comme la qualité de l'eau et les écosystèmes des prairies affectent également l'état de santé des pasteurs. Au Sahel, les enfants des communautés pastorales ont un meilleur statut nutritionnel saisonnier que les enfants sédentaires ; en revanche, chez les femmes de ces communautés la malnutrition aiguë est plus fréquente. En outre, les femmes sont plus en risque que les hommes d'être exclues des services de santé, pour différentes raisons déterminées par le contexte. Des évaluations factuelles des mesures de prophylaxie peuvent être réalisées au moyen d'enquêtes agrégatives comprenant l'évaluation simultanée de l'état sanitaire des personnes et des troupeaux, ce qui permet également de réunir des informations sur les coûts des maladies et des interventions sanitaires. Ces informations sont importantes pour étayer l'argumentaire des organisations tant gouvernementales que non gouvernementales en faveur d'un renforcement des interventions. Il est essentiel de faire appel aux nouveaux systèmes de surveillance intégrés « Une seule santé ¼, en utilisant les technologies mobiles, en prenant en compte les concepts locaux ainsi que l'expérience et les priorités des communautés pastorales et en les complétant par des informations solides recueillies sur le terrain, afin de concevoir et d'assurer des prestations de santé humaine et animale adaptées et inclusives, destinées aux communautés pastorales nomades et leur permettant de conserver leur mode de vie nomade.

La realización de estudios válidos de salud humana y animal, con seguimiento longitudinal de cohortes, no solo es un procedimiento factible entre los pastores nómadas, sino que además proporciona información básica a los organismos encargados de realizar intervenciones que se ajusten a la realidad sobre el terreno y respondan eficazmente a las necesidades de las sociedades pastorales. Estas, sin embargo, quedan con frecuencia excluidas de estudios, sistemas de vigilancia y programas sanitarios. La aparición de enfermedades que se pueden prevenir y tratar, como el tétanos perinatal, el sarampión o la tuberculosis, es indicativa de un acceso deficiente a los proveedores de asistencia sanitaria y a la información sobre cuestiones de salud. Con los recursos humanos y económicos de que disponen, a los servicios de salud les resulta difícil instaurar mecanismos para llegar eficazmente a esas poblaciones, lo que, entre otras consecuencias, se traduce en tasas de mortalidad materna inaceptablemente altas en las sociedades pastorales. En la morbilidad de esas poblaciones también influyen determinantes ambientales como la calidad del agua o los ecosistemas de pradera. En el Sahel, el estado de nutrición de los niños de las comunidades de pastores es mejor, según las estaciones, que el de los niños sedentarizados. Las mujeres de las sociedades pastorales, sin embargo, tienden a presentar índices más elevados de malnutrición aguda, y por diferentes razones ligadas al contexto, están más expuestas que los hombres a verse privadas de servicios de salud. Las medidas de control basadas en datos empíricos pueden ser evaluadas mediante estudios por conglomerados con valoración simultánea del estado de salud de las personas y el ganado, en los que también se obtienen datos sobre el costo de las enfermedades y las intervenciones sanitarias, datos que ofrecen a los organismos oficiales o no gubernamentales poderosos argumentos a la hora de definir intervenciones. Para concebir y dispensar servicios adaptados de salud humana y animal, que sin dejar de lado a las comunidades de pastores nómadas a la vez les permitan mantener su modo de vida itinerante, es esencial poner en solfa nuevos sistemas integrados de vigilancia, que se ajusten a los principios de «Una sola salud¼, aprovechen las tecnologías móviles y tengan en cuenta los conceptos y experiencias locales y las prioridades de las comunidades de pastores, combinándolos con la obtención de datos sólidos sobre el terreno.

Host sexual dimorphism and parasite adaptation.

In species with separate sexes, parasite prevalence and disease expression is often different between males and females. This effect has mainly been attributed to sex differences in host traits, such as immune response. Here, we make the case for how properties of the parasites themselves can also matter. Specifically, we suggest that differences between host sexes in many different traits, such as morphology and hormone levels, can impose selection on parasites. This selection can eventually lead to parasite adaptations specific to the host sex more commonly encountered, or to differential expression of parasite traits depending on which host sex they find themselves in. Parasites adapted to the sex of the host in this way can contribute to differences between males and females in disease prevalence and expression. Considering those possibilities can help shed light on host-parasite interactions, and impact epidemiological and medical science.

Safety of the blood supply.

BACKGROUND: The transfusion of blood components plays a significant role as supportive therapy in the treatment of patients with cancer. Although blood transfusions help manage complications arising from either the patient's primary condition or associated with therapeutic intervention, their use introduces a new set of risks; therefore, health care professionals must be aware of the potential morbidity introduced by using blood components and endeavor to optimize outcomes by ordering transfusions only when the benefits outweigh the inherent risks. METHODS: This article sought to review the published literature, including the epidemiology of diseases transmissible via transfusion, performance characteristics for assays used for blood donor screening, surveillance activities to detect newly emergent pathogens, and biovigilance activities reported by public health authorities. RESULTS: Effective measures have been implemented to significantly decrease the risk of transmissible diseases associated with transfusion. Reports of viral disease transmitted via transfusion have been nearly eliminated, particularly since the introduction of molecular-based detection technology. The transmission of bacteria and parasites still represents a threat to the use of cellular blood components. Transfusion-associated human prion disease has not been reported in the United States. Immune-mediated reactions due to donor-recipient incompatibility remain a challenge. CONCLUSIONS: Transmissible agents most commonly associated with risks due to transfusion are no longer a major threat; however, a significant challenge remains with regard to addressing the need for quick response mechanisms to manage emerging pathogens with the potential for rapid spread, either unintentionally (eg, globalization) or intentionally (eg, bioterrorism). The use of technology to reduce pathogens holds promise for further increasing the safety profile of blood transfusion.