Presse Med
-
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.
-
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.
-
In June 1981, the Centers for Disease Control (CDC) "Morbidity and Mortality Weekly Report" described the first cases of what was to be known as the Acquired Immunodeficiency Syndrome (AIDS). Two years later, the agent responsible for the disease, the human immunodeficiency virus (HIV), was identified. ⋯ Where does this virus come from, and why such an emergence in the late 20th century? These are the questions that it is now possible to answer in large part thanks to the numerous studies published over a little more than three decades. As with other emerging infectious diseases, initial cross-species transmission from an animal reservoir and subsequent favorable sociological factors associated with the evolution of human societies have led to the spread of a dramatic disease, for which no vaccine is presently available.
-
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 ?