Re-Emergence of Dengue and Emergence of Dengue Haemorrhagic Fever in the Americas

Dengue has been known in the Americas since the 18th century. During the 1960s and 1970s dengue pandemics occurred in the Caribbean, northern South America and Central America, and, during the 1980s and 1990s, virtually every country in the Americas experienced dengue epidemics. Dengue serotypes 1, 2 and 4 circulate widely and, since 1994, DEN-3 has circulated in Central America and Mexico. The first epidemic of dengue haemorrhagic fever in the Americas occurred in Cuba in 1981 with the introduction of DEN-2 four years after an epidemic of DEN-1, resulting in 344 203 cases, of which 10 312 were severe cases with 158 deaths. Subsequently, occasional cases of DHF occurred in the Americas until 1989-1990 when an epidemic occurred in Venezuela with 3 108 DHF cases and 73 deaths. Between 1981 and 1996 a total of 42 246 cases of DHF and 582 deaths were reported by 25 countries. Countries which reported more than 1000 cases each were Venezuela, Cuba, Colombia, Nicaragua and Mexico. Aedes aegypti, the vector of dengue in the Americas, was eradicated from 21 countries in the region during 1948-1972, but due to inadequate surveillance against re-infestation, these countries got infested again and suffered dengue epidemics. As of October 1997, all countries in the Americas, except Bermuda, Canada and Chile, are infested. Aedes albopictus, a vector of dengue in Asia, was first found in the Americas in 1985 and is now present in eight countries. Until now this mosquito has not been incriminated as a vector of any virus in the Americas. In 1997 the Directing Council of the Pan American Health Organization (PAHO) called on the Member countries to follow the hemispheric plan to expand and intensify efforts to combat Aedes aegypti with a view to its eventual eradication in the Americas. Re-Emergence of Dengue and Emergence of DHF in the Americas Dengue Bulletin – Vol 21, 1997 17 Historical overview The first description of a dengue-like disease in the Americas relates to an outbreak that occurred in Philadelphia, U.S.A., in 1780. In the following century four large epidemics, which occurred during 1827-28, 1850-51, 1879-80 and 1897-99, affected Caribbean countries and the southern United States. Interestingly, small-joint arthritis, including swelling, which are commonly found in infections associated with the arboviruses Chikun-gunya and Mayaro, were among the clinical manifestations observed during the dengue outbreaks between 1827-1880 but not during the ones which occurred after this period. In the first half of this century, four epidemics were reported in the same countries, the last one occurring during 1941-1946, which affected cities in the Texas Gulf, several Caribbean islands including Cuba, Puerto Rico and Bermuda, Mexico, Panama and Venezuela. In Brazil, epidemics of dengue were recorded during 1846-1848 and 1851-1853. Since then, until 1982, only two outbreaks were reported in 1916 and 1923. Peru reported cases of dengue during the 1950s but not in the following three decades. In 1953, dengue virus, which was identified as DEN-2, was isolated for the first time in the Americas in the island of Trinidad. Several isolates of DEN-2 were obtained from persons in the same island during 1953-1954 but, interestingly, no outbreaks were reported in this period in Trinidad nor in any other Caribbean island. Re-emergence of dengue During the 1960s two extensive pandemics of dengue affected the Caribbean and Venezuela. The first one which broke out in 1963 was due to DEN3 and swept the Caribbean after almost 20 years of silence. Jamaica, Puerto Rico, islands of the Lesser Antilles and Venezuela were among the countries affected but, interestingly, Cuba, Hispañiola and Trinidad were spared in this outbreak. The second epidemic occurred in the Caribbean and Venezuela during 1968-1969, and although DEN-2 was pre-dominantly isolated, DEN-3 was also recovered from persons in some islands. During the 1970s these two serotypes caused extensive epidemics in Colombia where dengue had not been recognized since 1952. The first epidemic occurred during 1971-1972 and was due to DEN-2 whereas the 1975-1977 epidemic was associated with DEN-3. It was estimated that more than a half million persons became infected; however, both the outbreaks occurred ‘silently’ for the most part or were confused with other illnesses and did not attract much attention of the