A distinct British approach to disease in the tropics has been identified in the recent historiography of colonial medicine: Mansonian tropical medicine, named after Sir Patrick Manson (1844–1922), the founder of the London School of Tropical Medicine. This essay examines Manson's study of filariasis (infection with the filarial nematode worm) and argues that his conceptual tools and research framework were derived from contemporary natural history. It investigates Manson's training in natural history at the University of Aberdeen, where some of his (...) teachers were closely associated with transcendental biology. The concepts of perfect adaptation and the harmony of nature were crucial to the formulation of his research problematic. This essay demonstrates that biogeographical concepts played an important part in Manson's research methodology. It also investigates how Manson's natural historical approach contributed to the making of so‐called Mansonian tropical medicine. (shrink)

Fast and effective detection of the causative agent of malaria in humans, protozoan Plasmodium parasites, is of crucial importance for increasing the effectiveness of treatment and to control a devastating disease that affects millions of people living in endemic areas. The microscopic examination of Giemsa‐stained blood films still remains the gold‐standard in Plasmodium detection today. However, there is a high demand for alternative diagnostic methods that are simple, fast, highly sensitive, ideally do not rely on blood‐drawing and can potentially be (...) conducted by the patients themselves. Here, the history of Plasmodium detection is discussed, and advantages and disadvantages of diagnostic methods that are currently being applied are assessed. (shrink)

Recent advances in immunology have provided a foundation of knowledge to understand many of the intricacies involved in manipulating the human response to fight parasitic infections, and a great deal has been learned from malaria vaccine efforts regarding strategies for developing parasite vaccines. There has been some encouraging progress in the development of a Chagas vaccine in animal models. A prize fund for Chagas could be instrumental in ensuring that these efforts are translated into products that benefit patients.

Despite the enormous progress made in the advancement of health technologies over the last century, infectious diseases continue to cause significant morbidity and mortality in developing countries. Neglected diseases are a subset of infectious diseases that lack treatments that are effective, simple to use, or affordable. Neglected diseases primarily affect populations in poor countries that do not constitute a lucrative market sector, thus failing to provide incentives for the pharmaceutical industry to conduct R&D for these (...) class='Hi'>diseases. Of the treatments that do exist for neglected diseases, most are completely out-dated, with poor side-effect profiles, cumbersome logistics of administration, and inadequate efficacy. Historically, the impetus for a majority of neglected disease research was driven by early 20th-century colonialism, and in the post-colonial era, these diseases have been virtually ignored. Of the 1556 New Chemical Entities brought to market during the 30-year period from 1975 to 2004, only 20 — less than 0.02% — were for neglected diseases. (shrink)

In the target article, we presented the hypothesis that parasite-stress variation was a causal factor in the variation of in-group assortative sociality, cross-nationally and across the United States, which we indexed with variables that measured different aspects of the strength of family ties and religiosity. We presented evidence supportive of our hypothesis in the form of analyses that controlled for variation in freedom, wealth resources, and wealth inequality across nations and the states of the USA. Here, we respond to criticisms (...) from commentators and attempt to clarify and expand the parasite-stress theory of sociality used to fuel our research presented in the target article. (shrink)

What is the origin of individual differences in ideology and personality? According to the parasite stress hypothesis, the structure of a society and the values of individuals within it are both influenced by the prevalence of infectious disease within the society's geographical region. High levels of infection threat are associated with more ethnocentric and collectivist social structures and greater adherence to social norms, as well as with socially conservative political ideology and less open but more conscientious personalities. Here we use (...) an agent-based model to explore a specific opportunities-parasites trade-off hypothesis, according to which utility-maximizing agents place themselves at an optimal point on a trade-off between the gains that may be achieved through accessing the resources of geographically or socially distant out-group members through openness to out-group interaction, and the losses arising due to consequently increased risks of exotic infection to which immunity has not been developed. We examine the evolution of cooperation and the formation of social groups within social networks, and we show that the groups that spontaneously form exhibit greater local rather than global cooperative networks when levels of infection are high. It is suggested that the OPTO model offers a first step toward understanding the specific mechanisms through which environmental conditions may influence cognition, ideology, personality, and social organization. (shrink)

In the target article, we presented the hypothesis that parasite-stress variation was a causal factor in the variation of in-group assortative sociality, cross-nationally and across the United States, which we indexed with variables that measured different aspects of the strength of family ties and religiosity. We presented evidence supportive of our hypothesis in the form of analyses that controlled for variation in freedom, wealth resources, and wealth inequality across nations and the states of the USA. Here, we respond to criticisms (...) from commentators and attempt to clarify and expand the parasite-stress theory of sociality used to fuel our research presented in the target article. (shrink)

In the last few years, annexins have been discovered in several nematodes and other parasites, and distinct differences between the parasite annexins and those of the hosts make them potentially attractive targets for anti‐parasite therapeutics. Annexins are ubiquitous proteins found in almost all organisms across all kingdoms. Here, we present an overview of novel annexins from parasitic organisms, and summarize their phylogenetic and biochemical properties, with a view to using them as drug or vaccine targets. Building on structural and (...) biological information that has been accumulated for mammalian and plant annexins, we describe a predicted additional secondary structure element found in many parasite annexins that may confer unique functional properties, and present a specific antigenic epitope for use as a vaccine. (shrink)

In the target article, we presented the hypothesis that parasite-stress variation was a causal factor in the variation of in-group assortative sociality, cross-nationally and across the United States, which we indexed with variables that measured different aspects of the strength of family ties and religiosity. We presented evidence supportive of our hypothesis in the form of analyses that controlled for variation in freedom, wealth resources, and wealth inequality across nations and the states of the USA. Here, we respond to criticisms (...) from commentators and attempt to clarify and expand the parasite-stress theory of sociality used to fuel our research presented in the target article. (shrink)

Although natural selection might be expected to reduce the incidence and severity of disease, disease persists. Natural selection leads to increases in the mean fitness of populations and so will reduce the frequency of disease-associated alleles, but other evolutionary processes, such as mutation and gene flow, may introduce or increase the frequency of these deleterious alleles. The pleiotropic actions of genes and the epistatic interactions between them complicate the relationship between genotype and phenotype, and may result in the preservation of (...) disease-associated alleles. Deleterious alleles may also be maintained because of linkage to beneficial alleles. The inability of natural selection to eliminate diseases of aging is a reminder that fitness – success in producing progeny, or in contributing genes to the population gene pool – is not equivalent to the absence of disease. Nutritional or psychosocial cues may lead to life history strategies that maximize survival to reproductive maturity at the expense of disease later in life. Natural selection acts on genes, cells, and groups, as well as on organisms; the outcome of evolution reflects selection at different levels of biological organization. Finally, the human environment is constantly changing, largely because of the evolution of our parasites and because of changes in cultural beliefs and practices; genetic evolution is comparatively slow and lags behind environmental change. An evolutionary nosology complements traditional medical nosologies and enhances our understanding of the persistence of disease and the meaning of human variation. (shrink)

Animal blood -- Fabricating noses -- The face transplant -- The Manson effect -- Robles' disease -- Chagas' error.

Many of the most virulent and problematic eukaryotic pathogens have evolved from photosynthetic ancestors, such as apicomplexans, which are responsible for a wide range of diseases including malaria and toxoplasmosis. The primary barrier to understanding the early stages of evolution of these parasites has been the difficulty in finding parasites with closely related free‐living lineages with which to make comparisons. Parasites found throughout the florideophyte red algal lineage, however, provide a unique and powerful model to investigate the genetic origins (...) of a parasitic lifestyle. This is because they share a recent common ancestor with an extant free‐living red algal species and parasitism has independently arisen over 100 times within this group. Here, we synthesize the relevant hypotheses with respect to how these parasites have proliferated. We also place red algal research in the context of recent developments in understanding the genome evolution of other eukaryotic photosynthesizers turned parasites. (shrink)

The interest of F. Macfarlane Burnet in host–parasite interactions grew through the 1920s and 1930s, culminating in his book, Biological Aspects of Infectious Disease, often regarded as the founding text of disease ecology. Our knowledge of the influences on Burnet’s ecological thinking is still incomplete. Burnet later attributed much of his conceptual development to his reading of British theoretical biology, especially the work of Julian Huxley and Charles Elton, and regretted he did not study Theobald Smith’s Parasitism and Disease until (...) after he had formulated his ideas. Scholars also have adduced Burnet’s fascination with natural history and the clinical and public health demands on his research effort, among other influences. I want to consider here additional contributions to Burnet’s ecological thinking, focusing on his intellectual milieu, placing his research in a settler society with exceptional expertise in environmental studies and pest management. In part, an ‘‘ecological turn’’ in Australian science in the 1930s, derived to a degree from British colonial scientific investments, shaped Burnet’s conceptual development. This raises the question of whether we might characterize, in postcolonial fashion, disease ecology, and other studies of parasitism, as successful settler colonial or dominion science. (shrink)

CRISPR‐Cas technology accelerates development of fast, accurate, and portable diagnostic tools, typified by recent applications in COVID‐19 diagnosis. Parasitic helminths cause devastating diseases afflicting 1.5 billion people globally, representing a significant public health and economic burden, especially in developing countries. Currently available diagnostic tests for worm infection are neither sufficiently sensitive nor field‐friendly for use in low‐endemic or resource‐poor settings, leading to underestimation of true prevalence rates. Mass drug administration programs are unsustainable long‐term, and diagnostic tools – required (...) to be rapid, specific, sensitive, cost‐effective, and user‐friendly without specialized equipment and expertise – are urgently needed for rapid mapping of helminthic diseases and monitoring control programs. We describe the key features of the CRISPR‐Cas12/13 system and emphasise its potential for the development of effective tools for the diagnosis of parasitic and other neglected tropical diseases (NTDs), a key recommendation of the NTDs 2021–2030 roadmap released by the World Health Organization. (shrink)

It has recently emerged that malarial, toxoplasmodial and related parasites contain a vestigial plastid (the organelle in which photosynthesis occurs in plants and algae). The function of the plastid in these obligate intracellular parasites has not been established. It seems likely that modern apicomplexans derive from photosynthetic predecessors, which perhaps formed associations with protists and invertebrates and abandoned autotrophy in favour of parasitism. Recognition of a third genetic compartment in these parasites proffers alternative strategies for combating a host of important (...) human and animal diseases. It also poses some fascinating questions about the evolutionary biology of this important group of pathogens. (shrink)

Reorganization of cell organelle‐deprived host red blood cells by the apicomplexan malaria parasite Plasmodium falciparum enables their cytoadherence to endothelial cells that line the microvasculature. This increases the time red blood cells infected with mature developmental stages remain within selected organs such as the brain to avoid the spleen passage, which can lead to severe complications and cumulate in patient death. The Maurer's clefts are a novel secretory organelle of parasite origin established by the parasite in the cytoplasm of the (...) host red blood cell in order to facilitate the establishment of cytoadherence by conducting the trafficking of immunovariant adhesins to the host cell surface. Another important function of the organelle is the sorting of other proteins the parasite traffics into its host cell. Although the organelle is of high importance for the pathology of malaria, additional putative functions, structure, and genesis remain shrouded in mystery more than a century after its discovery. In this review, we highlight our current knowledge about the Maurer's clefts and other novel secretory organelles established within the host cell cytoplasm by human‐pathogenic malaria parasites and other parasites that reside within human red blood cells. (shrink)

Nineteenth-century medical advances were entwined with a conceptual innovation: the idea that many cases of disease which were previously thought to have diverse causes could be explained by the action of a single kind of cause, for example a certain bacterial or parasitic infestation. The focus of modern epidemiology, however, is on chronic non-communicable diseases, which frequently do not seem to be attributable to any single causal factor. This paper is an effort to resolve the resulting tension. The (...) paper criticises the monocausal model of disease, so successful in the nineteenth century. It also argues that a multifactorial model of disease can only be satisfactory if it amounts to more than a mere rejection of the monocausal model. A third alternative, the contrastive model, is proposed and defended on the grounds that it links the notions of disease and of general explanation, while avoiding the philosophical naiveties and practical difficulties of the monocausal model. (shrink)

Why does the practice of the siesta vary across human cultures? One explanation is that it is a form of energy conservation in environments with high temperatures and/or agricultural labor. Disease palliation and prevention represents another area where the siesta might be beneficial. A preliminary study used the Human Relations Area Files (HRAF) to examine the characteristics associated with siesta occurrence. Siestas were not statistically associated with high temperatures or agricultural labor (p>.05). They were, however, statistically associated with the occurrence (...) of malaria (p<.05) and marginally associated with parasitic and chronic infectious disease. Preliminary results suggest that siestas could be adaptive in environments with chronic infectious disease. (shrink)

Entamoeba histolytica is a protozoan parasite of humans, and the causitive agent of intestinal amebiasis. The disease‐causing stage of the parasite is an osmotically sensitive ameboid form, which differentiates into a thick‐walled cyst for transmission from person to person. The conditions within the human intestine that induce encystment of the amoeba are unknown, but studies using an amoebic parasite of reptiles are now yielding information about the molecules and host:parasite interactions involved in the process. An understanding of the amoeba's obligatory (...) encystment pathway should provide an approach for interrupting the transmission of this parasite, for which there is currently no vaccine. (shrink)

Schistosomes are parasitic blood flukes, responsible for significant human disease in tropical and developing nations. Here we review information on the organization of the cytoskeleton and associated motor proteins of schistosomes, with particular reference to the organization of the syncytial tegument, a unique cellular adaptation of these and other neodermatan flatworms. Extensive EST databases show that the molecular constituents of the cytoskeleton and associated molecular systems are likely to be similar to those of other eukaryotes, although there are potentially (...) some molecules unique to schistosomes and platyhelminths. The biology of some components, particular those contributing to host–parasite interactions as well as chemotherapy and immunotherapy are discussed. Unresolved questions in relation to the structure and function of the tegument relate to dynamic organization of the syncytial layer. BioEssays 26:752–765, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

The link between parasite-stress and complex psychological dispositions implies that the social, political, and economic benefits likely to flow from public health interventions that reduce rates of non-zoonotic infectious disease are far greater than have traditionally been thought. We sketch a prudential and ethical argument for increasing public health resources globally and redistributing these to focus on the alleviation of parasite-stress in human populations.

Plasmodium falciparum is the most deadly human malarial parasite, responsible for an estimated 207 million cases of disease and 627,000 deaths in 2012. Recent studies reveal that the parasite actively regulates a large fraction of its genes throughout its replicative cycle inside human red blood cells and that epigenetics plays an important role in this precise gene regulation. Here, we discuss recent advances in our understanding of three aspects of epigenetic regulation in P. falciparum: changes in histone modifications, nucleosome occupancy (...) and the three‐dimensional genome structure. We compare these three aspects of the P. falciparum epigenome to those of other eukaryotes, and show that large‐scale compartmentalization is particularly important in determining histone decomposition and gene regulation in P. falciparum. We conclude by presenting a gene regulation model for P. falciparum that combines the described epigenetic factors, and by discussing the implications of this model for the future of malaria research. (shrink)

Zonulin is a physiological modulator of intercellular tight junctions, which upregulation is involved in several diseases like celiac disease (CeD). The polyQ gliadin fragment binds to the CXCR3 chemokine receptor that activates zonulin upregulation, leading to increased intestinal permeability in humans. Here, we report a general hypothesis based on the structural connection between the polyQ sequence of the immunogenic CeD protein, gliadin, and enteric coccidian parasites proteins. Firstly, a novel interaction pathway between the parasites and the host is described (...) based on the structural similarities between polyQ gliadin fragments and the parasite proteins. Secondly, a potential connection between coccidial infections as a novel environmental trigger of CeD is hypothesized. Therefore, this report represents a promising breakthrough for coccidian research and points out the potential role of coccidian parasites as a novel trigger of CeD that might define a preventive strategy for gluten‐related disorders in general. Also see the video abstract here: https://youtu.be/oMaQasStcFI. (shrink)

Many studies have attempted to assess the relative effects of different vectors of a disease on animal populations. To this end, three measures have been proposed: Vectorial efficiency, Vectorial capacity and recently Vectorial effectiveness (or Vectorial impact). In this study we relate these measures to derive some of their properties emphasising in the vectorial impact for its importance in both, population performance of parasites and the proportion of the prevalence of one parasite due to a given vector. We applied the (...) quantitative expressions advanced in this study to a simple Chilean example with one parasite (Trypanosoma cruzi), two vectors (Triatoma infestans and Mepraia spinolai) and one animal population (humans: Chagas's disease). (shrink)

The Swiss-born medical researcher Karl Friedrich Meyer is best known as a ‘microbe hunter’ who pioneered investigations into diseases at the intersection of animal and human health in California in the 1920s and 1930s. In particular, historians have singled out Meyer’s 1931 Ludwig Hektoen Lecture in which he described the animal kingdom as a ‘reservoir of disease’ as a forerunner of ‘one medicine’ approaches to emerging zoonoses. In so doing, however, historians risk overlooking Meyer’s other intellectual contributions. Developed in (...) a series of papers from the mid-1930s onwards, these were ordered around the concept of latent infections and sought to link microbial behavior to broader bio-ecological, environmental, and social factors that impact hostpathogen interactions. In this respect Meyer—like the comparative pathologist Theobald Smith and the immunologist Frank Macfarlane Burnet—can be seen as a pioneer of modern ideas of disease ecology. However, while Burnet’s and Smith’s contributions to this scientific field have been widely acknowledged, Meyer’s have been largely ignored. Drawing on Meyer’s published writings and private correspondence, this paper aims to correct that lacuna while contributing to a reorientation of the historiography of bacteriological epidemiology. In particular I trace Meyer’s intellectual exchanges with Smith, Burnet and the animal ecologist Charles Elton, over brucellosis, psittacosis and plague—exchanges that not only showed how environmental and ecological conditions could ‘tip the balance’ in favor of parasites but which transformed Meyer thinking about resistance to infection and disease. (shrink)

In this article, we argue that contemporary biomedicine is shaped by two, seemingly incommensurable, organizational logics, the ‘regime of truth’ and the ‘regime of hope’. We articulate their features by drawing on debates sparked by the recent clinical trial of a new approach to the treatment of Parkinson’s Disease. We also argue that the ‘self’ is configured in the very same process whereby these two organizational logics interlock and become mutually dependent, so that the ‘self’ might be said to be (...) the effect of a ‘parasitic’ relationship between the regimes of ‘truth’ and ‘hope’. We then bring these two arguments to bear on the contrasting views of the relationship between embodiment and political subjectivity articulated by Michel Foucault and Giorgio Agamben, on the one hand, and Paul Rabinow and Nikolas Rose, on the other hand. (shrink)

Individuals with trypophobia have an aversion towards clusters of roughly circular shapes, such as those on a sponge or the bubbles on a cup of coffee. It is unclear why the condition exists, given the harmless nature of typical eliciting stimuli. We suggest that aversion to clusters is an evolutionarily prepared response towards a class of stimuli that resemble cues to the presence of parasites and infectious disease. Trypophobia may be an exaggerated and overgeneralised version of this normally adaptive response. (...) Consistent with this explanation, individuals with trypophobia, as well as comparison individuals, reported aversion towards disease-relevant cluster stimuli, but only the trypophobic group reported aversion towards objectively harmless cluster stimuli that had no relevance to disease. For both groups the level of aversion reported was predicted uniquely by a measure of disgust sensitivity. Scaled emotion ratings and open-ended responses revealed that the aversive response was predominantly based on the disease avoidance emotion, disgust. Many open-ended responses also described skin sensations. These findings support the proposal that individuals with trypophobia primarily perceive cluster stimuli as cues to ectoparasites and skin-transmitted pathogens. (shrink)

During the cold war, Frank Fenner and Francis Ratcliffe studied mathematically the coevolution of host resistance and parasite virulence when myxomatosis was unleashed on Australia’s rabbit population. Later, Robert May called Fenner the “real hero” of disease ecology for his mathematical modeling of the epidemic. While Ratcliffe came from a tradition of animal ecology, Fenner developed an ecological orientation in World War II through his work on malaria control —that is, through studies of tropical medicine. This makes Fenner at least (...) a partial exception to other senior disease ecologists in the region, most of whom learned their ecology from examining responses to agricultural challenges and animal husbandry problems in settler colonial society. Here I consider the local ecologies of knowledge in southeastern Australia during this period, and describe the particular cold-war intellectual niche that Fenner and Ratcliffe inhabited. (shrink)

Skeletons drawn from archaeological contexts provide a fund of data for assessing disease in general and timing of epidemics in particular in past societies. The bioarchaeological record presents an especially important perspective on timing of some of the world's most catastrophic diseases, such as leprosy, tuberculosis, plague (Black Death), and treponematosis. Application of new developments in paleogenomics and paleogenetics presents new opportunities to document ancient pathogens' DNA (for example, Black Death), track their history, and assess their beginning and end (...) points. Paleopathological documentation of disease terminus is complex, in part owing to circumstances where past communities experienced overlapping epidemics, such as leprosy and plague. For most settings, these syndemics-whereby there is an interaction between two or more epidemic diseases-both exacerbate and enhance the burden of morbidity in a community or region. Fundamental to understanding the severity and duration of epidemics is the consideration of multiple factors that simultaneously influence the severity and duration of the specific infectious diseases in a community or region, including poor oral health, under-nutrition, iron deficiency anemia, and elevated parasite load. In our view, comprehending the beginning, the middle, and the end of epidemics requires understanding the wider context of syndemics, the multiple challenging circumstances that undermine health and community stability, and how biosocial factors differentially affect the immune competence of individuals. This article provides several examples of the application of bioarchaeology and syndemics theory in achieving an understanding of how epidemics end. Pathogens continue to circulate, even after what appears to be the end. In effect, then, there is no “end,” just evolution of opportunistic pathogens and our ability (or not) to mitigate them. (shrink)

Leishmania major infection of inbred mice leads to a major dichotomous response—death or survival—that depends on the strain of mice. This finding has motivated efforts to locate genetic determinants of disease susceptibility. Genotyping studies have confirmed a complex multilocus trait, but studies directed at the biology of the response suggest identifiable components of susceptibility that may direct the genetic investigations. A confluence of parasite variables—residence in macrophages, class II-dependent immunity, and avoidance of early IL-12 induction—with host factors—a prominent helper T-cell (...) precursor frequency to a dominant parasite epitope and a bias in IL-4 gene activation—conspires to drive an aberrant immune response in animals that suffer fatal disease. These insights may lead to an understanding of factors that focus responses on dominant antigens and that mold the naive T-cell repertoire. Collectively, such factors might contribute to the pathogenesis of other infectious and autoimmune diseases. BioEssays 21:510–518, 1999. © 1999 John Wiley & Sons, Inc. (shrink)

American Trypanosomiasis, known as Chagas disease, was discovered in 1909 under peculiar circumstances: its discoverer, Carlos Chagas, was sent to a small village of Central Brazil to carry out an anti-malaria campaign when he came across a blood sucking insect—the vector for the parasite infection. He had been alerted to the coincidence of peculiar symptoms and the presence of this insect in the wood and earth dwellings of the region. He was deeply involved in theoretical controversies in international protozoology; he (...) was engaged in the consolidation of a scientific role and corresponding institutional conditions in Brazil, and equally immersed in the nationalist sanitary struggles of his days. In these contexts, Chagas assembled a remarkable discovery discourse, regarding the biology of the parasite, its life cycle and mode of transmission. Furthermore, he provided the clinical description of a new disease. Despite immediate international recognition, however, the unstable institutional arrangements surrounding his work damaged its local legitimacy for decades. His authority was widely recognized abroad, but rejected at home. (shrink)

Infectious and parasitic diseases cause enormous health problems in the developing world whereas they leave the developed one relatively unscathed. Research and development (R&D) of drugs for diseases that mainly affect people in developing countries is limited. The problem that relatively few drugs are available for diseases that cause an enormous burden of disease in the developing world is called the 'availability problem'. In recent years, the availability problem has received quite a bit of attention. A (...) number of proposals have been fielded as to how this problem might be minimized. Wild-card patent extensions, advance market commitments, cash prizes and the Health Impact Fund are prominent examples of such proposals. These proposals can be thought of as pull-mechanisms for R&D of drugs for neglected diseases. What has been coined a 'priority review voucher' is another pull-mechanism. This paper is a critical discussion of this pull-mechanism. First, the original priority review voucher scheme, as proposed by Ridley et al. (2006), is described. A number of objections to this scheme are thereafter presented. A few amendments to the original scheme are then suggested, and it is argued that with these amendments in place, the priority review voucher scheme constitutes an attractive way of stimulating R&D of drugs for neglected diseases. (shrink)

Development of a vaccine for schistosomiasis, a parasitic disease currently affecting over 200 million people worldwide, has been targeted as a priority by the World Health Organisation. Research demonstrating the ability of humans to acquire natural immunity to schistosome infection, together with the successful use of attenuated vaccines in animals both under laboratory and field conditions, suggest that development of a human vaccine is feasible. Attenuated vaccines for schistosomiasis are considered neither safe nor practicable for human use, however, and (...) therefore other approaches must be considered. This review examines progress currently being undertaken in a number of different areas towards achieving the goal of a safe and effective human vaccine for schistosomiasis. (shrink)

Infectious and parasitic diseases cause massive health problems in the developing world. Research and development of drugs for diseases that mainly affect poor people in developing countries is limited. The advance market commitment (AMC) idea is an incentivising mechanism for research and development of drugs for neglected diseases. Discussion of the AMC idea is of renewed interest given the launch in June 2009 of the first AMC. This pilot AMC is designed to, among other things, test (...) the idea for potential future applications. This paper is a critique of the AMC idea. It seeks to show that the idea has a hitherto unrecognised theoretical flaw that should make policy-makers and donors hesitant to embrace future applications of the idea. (shrink)

Malaria is a Plasmodium parasitic disease transmitted by infected female Anopheles mosquitoes. Climatic factors, such as temperature, humidity, rainfall, and wind, have significant effects on the incidence of most vector-borne diseases, including malaria. The mosquito behavior, life cycle, and overall fitness are affected by these climatic factors. This paper presents the results obtained from investigating the optimal control strategies for malaria in the presence of temperature variation using a temperature-dependent malaria model. The study further identified the temperature ranges (...) in four different geographical regions of sub-Saharan Africa, suitable for mosquitoes. The optimal control strategies in the temperature suitable ranges suggest, on average, a high usage of both larvicides and adulticides followed by a moderate usage of personal protection such as bednet. The average optimal bednet usage mimics the solution profile of the mosquitoes as the mosquitoes respond to changes in temperature. Following the results from the optimal control, this study also investigates using a temperature-dependent model with insecticide-sensitive and insecticide-resistant mosquitoes the impact of insecticide-resistant mosquitoes on disease burden when temperature varies. The results obtained indicate that optimal bednet usage on average is higher when insecticide-resistant mosquitoes are present. Besides, the average bednet usage increases as temperature increases to the optimal temperature suitable for mosquitoes, and it decreases after that, a pattern similar to earlier results involving insecticide-sensitive mosquitoes. Thus, personal protection, particularly the use of bednets, should be encouraged not only at low temperatures but particularly at high temperatures when individuals avoid the use of bednets. Furthermore, control and reduction of malaria may be possible even when mosquitoes develop resistance to insecticides. (shrink)

This study is based on the 1983 Rural Health Survey of Ethiopia. Patterns and levels of child morbidity by age, sex, geographic region, and sanitary facilities are examined. Morbidity levels peak in the second year of life. Diarrhoeal diseases are of major importance, especially among infants and toddlers. Parasitic diseases, and respiratory diseases other than pneumonia, become increasingly important with age.There are no significant sex differentials in morbidity except for higher rates of diarrhoeal diseases among (...) female children. Geographic differentials are quite marked with particularly high morbidity levels from all disease types in the western mountainous regions of Ethiopia. Access to high quality drinking water, a latrine, and garbage disposal, are strongly related to reduced overall morbidity levels, though not necessarily to reduced diarrhoeal disease levels. (shrink)

This paper examines mortality by cause of death in a rural area of Machakos district in Kenya. The cause-of-death data collected between 1975 and 1978 were likely to be of fairly good quality. The number of deaths was higher among infants and children. Infectious diseases and diseases of the respiratory system were the leading causes of death among children below 5 years of age. Next in prominence were the causes ascribed to congenital anomalies and perinatal conditions.Among adolescents and (...) young adults, injury and poisoning, together with tuberculosis and other infectious and parasitic diseases, were the leading causes of death. Degenerative diseases, especially diseases of the circulatory system and neoplasms and respiratory illness, were responsible for the majority of deaths among the older population. (shrink)

Similar to parasites, malignant cells exploit the host for energy, resources and protection, thereby impairing host health and fitness. Although cancer is widespread in the animal kingdom, its impact on life history traits and strategies have rarely been documented. Devil facial tumour disease, a transmissible cancer, afflicting Tasmanian devils, provides an ideal model system to monitor the impact of cancer on host life-history, and to elucidate the evolutionary arms-race between malignant cells and their hosts. Here we provide an overview of (...) parasite-induced host life history adaptations, then both phenotypic plasticity of LH responses and changes in allele frequencies that affect LH traits of Tasmanian devils in response to DFTD are discussed. We conclude that akin to parasites, cancer can directly and indirectly affect devil LH traits and trigger host evolutionary responses. Consequently, it is important to consider oncogenic processes as a selective force in wildlife. Exposure to transmissible cancer cells, i.e., Tasmanian devil facial tumour cells, can cause changes to life history traits either as the result of phenotypic plasticity in response to exposure during the lifetime of the individual or as the result of evolutionary change in LH traits due to selection over generations.Photo credits: Frédéric Thomas, Sarah Peck, Geordie Jennings. (shrink)

Definitive diagnosis of malaria requires the demonstration through laboratory tests of the presence within the patient of malaria parasites or their components. Since malaria parasites can be present even in the absence of malaria manifestations, and since symptoms of malaria can be manifested even in the absence of malaria parasites, malaria diagnosis raises important issues for the adequate understanding of disease, etiology and diagnosis. One approach to the resolution of these issues adopts a realist view, according to which the needed (...) clarifications will be derived from a careful representation of the entities on the side of the patient which form the ultimate truthmakers for clinical statements. We here address a challenge to this realist approach relating to the diagnosis of malaria, and show how this challenge can be resolved by appeal to Basic Formal Ontology (BFO) and to the Ontology for General Medical Science (OGMS) constructed in its terms. (shrink)

Self-medication behaviour is the use of natural materials or chemical substances to manipulate behaviour or alter the body’s response to parasites or pathogens. Self-medication can be preventive, performed before an individual becomes infected or diseased, and/or therapeutic, performed after an individual becomes infected or diseased. We summarized all available reports of self-medication in mammals and reconstructed its evolution. We found that reports of self-medication were restricted to eutherian mammals and evolved at least four times independently. Self-medication was most commonly reported (...) in primates. Detailed analyses of primates suggest that self-medication is a life-history trait associated with body size, absolute brain size and longevity, but we found no support for the hypothesis that self-medication evolved to reduce the costs of social living. Large, longer-lived species might thus benefit uniquely from self-medication. (shrink)

Application of evolutionary principles to epidemiological problems indicates that cultural characteristics influence the evolution of parasite virulence by influencing the success of disease transmission from immobilized, infected hosts. This hypothesis is supported by positive correlations between virulence and transmission by biological vectors, water, and institutional attendants. The general evolutionary argument is then applied to the causes and consequences of increased virulence for three diseases: cholera, influenza and AIDS.

Giardia lamblia, a protozoan parasite that causes widespread diarrheal disease, expresses a surface membrane associated lectin, taglin, which is specifically activated by limited proteolysis with trypsin, a protease that is present in abundance at the site of infection. When activated, taglin agglutinates enterocytes which are the cells to which the parasite adheres in vivo, and in addition, binds to isolated brush border membranes of these cells. These findings suggest that this lectin may be involved in the host‐parasite interaction. Taglin is (...) most specific for terminal phosphomannosyl residues and its binding to red cells is mediated by cell surface phosphate residues. Hemagglutinating activity induced by taglin is most active at pH6.5 and is dependent on divalent cations. A monoclonal antibody to taglin reacts with the surface membrane of live trophozoites and recognizes a protein of 28/30 kDa in lysates of Giardia trophozoites, by immunoblotting. This finding is confirmed by direct demonstration of lectin activity by erythrocyte binding to proteins electroblotted to nitrocellulose, which revealed specific red cell binding to giardial protein bands in the same molecular weight range as those recognized by the monoclonal antibody. (shrink)

Transmissible cancers are elusive and understudied parasitic life forms caused by malignant clonal cells (nine lineages are known so far). They emerge by completing sequential steps that include breaking cell cooperation, evade anti‐cancer defences and shedding cells to infect new hosts. Transmissible cancers impair host fitness, and their importance as selective force is likely largely underestimated. It is, therefore, crucial to determine how common they might be in the wild. Here, we draw a parallel between the steps required for (...) a transmissible cancer to emerge and the steps required for an intelligent civilisation to emerge in the Milky Way using a modified Drake equation. Using numerical analyses, we estimate the potential number of extant marine and bivalve species in which transmissible cancers might exist. Our results suggest that transmissible cancers are more common than expected, and that new lineages can be found by screening a large number of species. (shrink)

Frederick Griffith was an English bacteriologist at the Pathological Laboratory of the Ministry of Health in London who believed that progress in the epidemiology and control of infectious diseases would come only with more precise knowledge of the identity of the causative microorganisms. Over the years, Griffith developed and expanded a serological technique for identifying pathogenic microorganisms, which allowed the tracing of the sources of infectious disease outbreaks: slide agglutination. Yet Griffith is not remembered for his contributions to the (...) biology and epidemiology of infectious diseases so much as for discovering the phenomenon known as ‘transformation’. Griffith’s discovery, for many, was a pure case of serendipity whose biological relevance had also largely escaped him. In this paper, I argue that the key to understanding the significance of bacterial transformation – and the scientific legacy of Fred Griffith – rests not only on it initiating a cascade of events leading to molecular genetics but also on its implications for epidemiology based on the biology of host–parasite interactions. Looking at Griffith’s entire career, instead of focusing only on the transformation study, we can better appreciate the place of the latter within Griffith’s overall contributions. Presented in this way, Griffith’s experiment on bacterial transformation also ceases to appear as an anomaly, which in turn leads us to rethink some of the most prevalent historical conceptions about his work. (shrink)

Each year, over 200 million people are infected with the malaria parasite, nearly half a million of whom succumb to the disease. Emerging genetic technologies could, in theory, eliminate the burden of malaria throughout the world by intentionally eradicating the mosquitoes that transmit the disease. In this paper, we offer an ethical examination of the intentional eradication of Anopheles gambiae, the main malaria vector of sub-Saharan Africa. In our evaluation, we focus on two main considerations: the benefit of alleviating the (...) malaria burden, and the loss of value that would accompany the eradication of the species. We outline a typology of the different ways in which species are valued or could be valuable, then use that typology to appraise the value of the species in question. We argue that Anopheles gambiae has minor (and redundant) instrumental value, little final subjective value and no objective final value. (shrink)

"The total amount of suffering per year in the natural world is beyond all decent contemplation. During the minute that it takes me to compose this sentence, thousands of animals are being eaten alive, others are running for their lives, whimpering with fear, others are being slowly devoured from within by rasping parasites, thousands of all k inds are dying of starvation, thirst and disease. It must be so." -/- —Richard Dawkins, River Out of Eden (1995).

This book is an attempt to write about Kierkegaard's philosophy in the style of Kierkegaard's philosophy: energetic, playful, free spirited, surprising, and joyous. It is a deliberately crumby book in the sense that it seeks out the fragments, scraps, and crumbs of philosophical arguments that are generally ignored or swept away, like so much rubbish, but that are actually the most interesting parts of the meal. The Anti-Assistant-Professor Method that this book follows adopts Kierkegaard's many excellent jokes about assistant professors (...) as a guide to how not to write about Kierkegaard's philosophy; specifically: - Don't cease to be human. - Don't be a parasite, merely feeding off other people's creations and never creating anything new. - Don't reduce or simplify or systematize Kierkegaard's ideas in order to make life easier for everyone (because that was never the point). - Don't kill Kierkegaard's philosophy by lecturing on it, thereby turning it into a collection of dead ideas for nonhumans rather than subjective truths that need to be lived. Following these guidelines, the book attempts to extend and amplify some of Kierkegaard's most important ideas in a way that combats the persistent problem of nihilism--a disease that even Kierkegaard succumbed to at the end of his life. (shrink)