Ancient horizontal transfers of retrotransposons between birds and ancestors of human pathogenic nematodes.

Parasite host switches may trigger disease emergence, but prehistoric host ranges are often unknowable. Lymphatic filariasis and loiasis are major human diseases caused by the insect-borne filarial nematodes Brugia, Wuchereria and Loa. Here we show that the genomes of these nematodes and seven tropical bird lineages exclusively share a novel retrotransposon, AviRTE, resulting from horizontal transfer (HT). AviRTE subfamilies exhibit 83-99% nucleotide identity between genomes, and their phylogenetic distribution, paleobiogeography and invasion times suggest that HTs involved filarial nematodes. The HTs between bird and nematode genomes took place in two pantropical waves, >25-22 million years ago (Myr ago) involving the Brugia/Wuchereria lineage and >20-17 Myr ago involving the Loa lineage. Contrary to the expectation from the mammal-dominated host range of filarial nematodes, we hypothesize that these major human pathogens may have independently evolved from bird endoparasites that formerly infected the global breadth of avian biodiversity.

Discovery and clinical importance of the filariases.

Macrofilariae have been recognized for many millennia. Microfilariae were, however, not demonstrable until microscopy attained an advanced degree of perfection. Demonstration of the mode of transmission of the various filariases (Wuchereria bancrofti, Onchocerca volvulus, and Loa loa), dominated by Manson's work on lymphatic filariasis, constitutes one of the most exciting phases inhuman parasitology.

Human onchocerciasis in Brazil: an overview

The article reports on the history of the disease`s discovery, its distribution, and incrimination of vector simuliid species. The literature that has been generated on the parasite, its vectors, and control of the disease is critically analyzed as well as the organization of epidemiological surveys and the control program developed by the Brazilian government and an international agency. Suggestions for future work are made. (AU)

Natural history of parasitic disease. Patrick Manson's philosophical method.

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.

The social factors affecting the diffusion of parasitology to Puerto Rico and Hong Kong.

This study seeks to understand the role played by social factors in the diffusion of parasitology to Puerto Rico, in particular those affecting the work of Bailey K. Ashford between 1898-1934. Most studies of Ashford to date focus mainly on the intellectual framework per se, and rarely on the surrounding social environment. In order to achieve this aim, Ashford's experiences were contrasted to those of Patrick Manson in Hong Kong and China between 1866 and 1889. By undertaking this comparative approach, it became clear that social factors more significantly affected the advancement on their respective investigations than intellectual ones. Manson simply did not have the political and financial support needed to develop his work, hence greatly delaying the establishment of a research institute in Hong Kong, or China for that matter. By contrast, Ashford achieved a great deal of popular and congressional support, thereby enabling him to establish a research institution early in the century. Relevant social factors included: cultural differences, their history of colonial relations and the local economy.

Framing tropical disease in London: Patrick Manson, Filaria perstans, and the Uganda sleeping sickness epidemic, 1891-1902.

Much of the historical literature on tropical medicine represents the periphery as the chief site for the production of western knowledge about disease in the British empire. This study on the Filaria perstans-sleeping sickness hypothesis revises this perspective by showing how the imperial metropole functioned as a culture space for the construction of knowledge about the empire. Beginning in 1891, Patrick Manson used the publicity resources of London to generate a rhetorical imperative for the confirmation of his hypothesis without ever leaving Britain. Later, while he was medical adviser to the imperial state, the 1900 sleeping sickness epidemic in Uganda presented Manson with a unique opportunity to determine the validity of his hypothesis. By exaggerating the possible spread of the epidemic privately among Foreign Office personnel and publicly in the medical press, he succeeded in mobilizing the first Royal Society sleeping sickness research expedition to Africa in 1902. While this expedition ultimately disproved Manson's hypothesis, this outcome ironically created the very conditions for the identification of the actual causal agent (Trypanosoma gambiense) and its vector (tsetse fly) by Aldo Castellani and David Bruce respectively.

[Filariasis in Haiti: a century of history]. / Filarioses en Haïti: un siècle d'histoire.

Wuchereria bancrofti and Mansonella ozzardi are both endemic in Haiti. Over the last hundred years, these human parasites have been by turn investigated and disregarded. Between 1894 and 1914, Haitian physicians encouraged by Dr. Léon AUDAIN studied the clinical and biological impact of W. bancrofti in the numerous infested patients in Port-au-Prince. During the American occupation (1915-1934), the presence of M. ozzardi was recognized by a Rockefeller mission and a first investigation of filariasis distribution in the country was carried out. Between 1935 and 1971, interest in the parasites ceased. However, many studies of W. bancrofti and M. ozzardi and their vectors have been conducted from 1972 until today. Lymphatic filariasis remains a great health hazard in localized leeward foci, where climatic conditions favourise the survival of the vector Culex quinque-fasciatus. Urban foci have been remarkably stable for the last 70 years in northern Haiti and along the Gulf of the Gonâve coast. Parasitological indices are high and the impact on public health is great. Ozzardiasis is prevalent in the rural coastal areas of northern and southern Haiti, where the principal vectors Culicoides furens and C. barbosai breed in abundance. The control of lymphatic filariasis is now possible and should be a public health priority in Haiti.

Filariasis (Shlipada).

Filariasis is known to medical science over many centuries. It is a disease of tropical countries due to the presence of microfilaria. The effected areas are large and elephantoid in appearance, so it is called 'Elephantiasis'. A non-parasitic form of Elephantiasis occurs when the lymphatics are blocked. In Ayurveda this disease is termed as Shlipada.

[Historical epidemiology of bancroftian filariasis in southwest islands of the Indian Ocean]. / Epidémiologie historique de la filariose de bancroft dans les îles du sud-ouest de l'Océan Indien.

Bancroftian filariasis arose in the South-West Indian Ocean Islands with human settlements. During the XIXe century, most of the islands were infected but the prevalence and clinical features of the disease were different from an Island to an other. The vectors are Cx. quinquefasciatus, An. gambiae, An. arabiensis, An. funestus. Even if Culex are proven vectors most of the transmission is due to anophelines. The introduction of the parasite was followed by an explosion of the diseases with dramatic clinical features. But since the beginning of the century the disease retreats. Whatever this is due to malaria vector control and specifies chemoprophylaxis or is linked to the rise of life standard is still a subject of debate.

An historical review of malaria, kala-azar and filariasis in Bangladesh in relation to the Flood Action Plan.

This paper reviews the evidence of a link between flood control and vector-borne disease in Bengal/Bangladesh. Malaria is historically associated with reduced flooding and embankment construction in the flood plains of Bengal. The land west and south of the Jamuna river was highly malarious in 1916 but is not so today. The lands east of the Jamuna now have a higher, though still small, risk. The reduction in health risk can be attributed to the intensification of land use and human population density. Although there are many mosquito species, the abundance of the former malaria vector appears to have declined as environmental change removed its breeding sites. Visceral leishmaniasis (kala-azar) is a serious disease which is fatal if left untreated. It occurs in irregular, periodic epidemics and is currently increasing in Bangladesh. In the past, malaria and kala-azar were confused and the prevalence of both may have been increased by embankment programmes. Both diseases are unstable and there is insufficient historical information to predict, with certainty, the consequences of environmental change. Reduced flooding accompanied by increased pollution will probably control the malaria vector. More information is needed about the response of the kala-azar vector to flooding. Bancroftian filariasis is non-fatal but causes chronic morbidity. It has had a widespread but usually low prevalence in Bangladesh, with both rural and urban foci. There are few recent data. Increasing organic pollution and drainage obstruction are expected to favour the vector and increase transmission.