Slave Trade Carried Bilharzia-Causing Schistosome Parasites from West Africa to New World, Genomic Studies Confirm

The bilharzia-causing parasite, Schistosoma mansoni, first infected humans as they fished in lakes in East Africa and was spread, first to West Africa and then to the New World by slave traders in the 16th-19th centuries, new genomic studies have revealed. Wellcome Trust Sanger Institute, Imperial College London, and Royal Veterinary College scientists used the full DNA sequences of Schistosoma mansoni parasites from Africa and the French Caribbean to discover the fluke's origins, map its historic transmission, and identify the secrets of its success. Their findings show how the global slave trade transported the disease from Senegal and Cameroon in west Africa to Guadeloupe in the southern Caribbean. Further genomic comparison with a closely related schistosome species that infects rodents revealed how the parasite has adapted to infecting human beings. The new work was reported in an article published online on February 16, 2016 in Scientific Reports, The article is titled “Whole Genome Resequencing of the Human Parasite Schistosoma Mansoni Reveals Population History and Effects of Selection.” Schistosoma mansoni is a blood fluke (flatworm) that infects more than 250 million people worldwide and causes more than 11,000 deaths each year. Six years ago, the Sanger Institute published the parasite's first full DNA sequence (genome); this latest study used that “genetic map” to construct and compare the genomes of S. mansoni parasites gathered from across Africa and the New World, the majority of which were held at the Schistosomiasis Collection in the Natural History Museum, London. By analyzing the differences between the human-infecting S. mansoni and its close relative, the rodent-infecting S.
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