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.

Historical note on Loa loa: a reinterpretation.

Loa loa, also known as the African eye worm, is a common parasite in the central part of West Africa. As Chrysops silacea and C. dimidiata, the only important vectors of loaiasis, are found exclusively in the tropical rain forests of West Africa, the parasite's transmission is confined to this region. References by early writers to the extraction of Loa loa from the eye of a man on the Island of Ormus (today known as Hormuz or Hormus) in the Persian Gulf apparently were based on a misinterpretation of an illustration by de Bry (1595) of the blinding of a royal relative.

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.

[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.

[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.