Presse Med
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The cholera epidemic that hit Haiti from October 2010 to February 2019 was the world's deadliest of the last 25 years. Officially, the successive waves caused 9789 deaths, although numerous additional casualties could not be recorded. The origin of this epidemic has been the subject of a controversy involving two opposing theories. ⋯ Case-area targeted interventions aimed at interrupting cholera transmission were reinforced, which resulted in the extinction of the epidemic within two years. In the meantime, several phylogenetic studies on Vibrio cholerae during the seventh cholera pandemic demonstrated that local environmental and global epidemic Vibrio populations were distinct. These studies also showed that epidemics arose when the bacterium had diversified and that it had spread during transmission events associated with human travel.
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For millions of years, invertebrates and malaria parasites have coexisted and to date, malaria remains the most important human parasitic disease. This co-evolution had profound impacts on the movements of early hominids and on the genome of modern humans. ⋯ Over recent years the economic and social costs of malaria have been recognized and more funds have been mobilized than ever before, however further efforts are needed. National programs, international institutions and researchers will need to do better if the preventable deaths of hundreds of thousands of mostly African children are to be averted.
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Yellow fever is a zoonotic arbovirosis, the agent of which is transmitted by mosquitoes. In humans, this virus can cause hemorrhagic hepato-nephritis, while mild or inapparent infections are common. The catastrophic epidemics that occurred, mainly in the 18th and the 19th centuries, in Latin America and the United States as well as in the port cities of West Africa and Europe, had considerable demographic, socio-economic and political repercussions. ⋯ Risks of epidemics reappeared, in Latin America as well as Africa. In the early 21st century, epidemiologists are worried about these resurgences, especially since we still have no indisputable explanation for the absence of the disease on the Asian continent. Obviously, yellow fever is not a disease of the past.
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Smallpox is an ancient scourge known since the Antiquity. It is caused by a highly contagious airborne poxvirus. This strictly human disease exists in two forms: variola major (Asian smallpox) with mortality of 20-45%, and an attenuated form called variola minor or alatrim with mortality of 1-2%, which only recently appeared in Europe and America towards the end of the 19th century. ⋯ Using molecular approach, it has been discovered that the smallpox virus emerged 3000-4000 years ago in East Africa and is closely related to the taterapox virus from African gerbils and to the camelpox virus, which causes variola in camelids. Today, smallpox virus strains are stored in freezers at the CDC in Atlanta and at the Vector Center in Koltsovo, Siberia. That is why smallpox remains a potential threat to the highly susceptible human species, as a result of an accident or malicious use of the virus as a biological weapon.
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The "Russian flu", which raged from 1889 to 1894, is considered as the first pandemic of the industrial era for which statistics have been collected. This planetary event started in Turkestan and hit the Russian Empire, before reaching all European countries, the United States of America, and the whole world. Contemporaries were surprised by its high contagiousness as evidenced by attack rates averaging 60% in urban populations, its rapid spread in successive waves circling the globe in a few months by rail and sea, and the tendency of the disease to relapse. ⋯ All of these viruses are of animal origin. Recently, phylogenetic studies have revealed the genetic proximity between a bovine coronavirus BCoV and the human virus HCoV-OC43, indicating that the latter emerged around 1890, at the time of the Russian flu, when an epizootic was raging among cattle throughout Europe. Could the current human virus be the attenuated remnant that appeared after the Russian flu in 1894? Was there a coronavirus pandemic before Covid-19 ?