Yellow fever is a zoonosis of the tropical regions of South America and Africa, which occurs in two distinct epidemiologic cycles: jungle and urban.
In the jungle cycle, the virus spreads among monkeys and humans, who may be infected when they enter the jungle and are bitten by mosquitoes infected with the yellow fever virus. Urban yellow fever has long been eradicated from the Americas, with the last cases occurring in Brazil in 1942.
Since the 1970s, the area where jungle yellow fever (JYF) cases have occurred has been restricted to the northern region of the South American continent. From 1985 to December 2007, 3,837 cases of JYF have been reported, with 2,229 deaths.
In 2007 and the beginning of 2008, Brazil reported an intense and extensive epizootic of Jungle Yellow Fever in an area encompassing 6 states (Goi?s, the Federal District, Mato Grosso do Sul, Minas Gerais, Tocantins, and S?o Paulo). The State Health Departments have confirmed the epizootic based on laboratory and clinical epidemiological criteria. In the past two months, 26 confirmed human cases were reported in 3 Federal States (Goi?s, Mato Grosso do Sul, and the Federal District); 13 of the patients died. The affected areas have high vaccination coverage. Nevertheless, as part of ongoing control measures, health authorities have intensified vaccination for people living in or traveling to affected areas.
On 15 January 2008, the national health authorities of Paraguay reported their first confirmed cases of Jungle Yellow Fever. One of the cases was confirmed using molecular techniques; the other four, by epidemiological nexus. As of 11 February 2008, 4 other suspected cases of JYF have been reported. All the confirmed cases reported by the national health authorities come from a rural area of San Pedro department in the northern part of the country. National health authorities have intensified epidemiological surveillance for the detection and investigation of suspected cases, and yellow fever vaccination for people living in or traveling to the affected area.