Historical Facts About Dengue Fever

Dr. Carlos Jiménez
Medical Director, Presby Primary Healthcare
El Presby

Dengue fever is a disease caused by viruses transmitted through mosquitoes and it has four known serotypes. It is usually found in tropical and subtropical regions throughout the world, mainly in urban or suburban areas. It is regarded as the leading human arboviral disease (a viral disease transmitted by insects), affecting some 50 to 100 million people each year. Classical dengue fever is characterized by the acute onset of high fever, headache, generalized muscle and joint pain, nausea, vomiting, reduction in white blood cell and platelets count, and, frequently, skin rash. The more severe forms of the disease produce hemorrhaging or intravascular fluid leakage and are known, respectively, as Dengue Hemorrhaging Fever (DHF) and Dengue Shock Syndrome (DSS). Both of them can be fatal.

The four dengue fever serotypes are different from one another so if an infection by one type does occur, it will not create immunity to the other types. This means that people can become infected more than once. There is evidence that second-time infections have a greater probability of turning into the more severe forms (DHF or DSS) of the disease.

The precise origin or dengue fever is unknown, but clinical episodes resembling those of dengue fever have been reported in Chinese encyclopedias since the year 265 A.D. Ancient Chinese physicians were already aware that the disease was related to flying insects associated with water. The term "dengue fever" originated in America around 1827 due to a Caribbean epidemic that presented with fever, generalized body aches and a skin rash. African slaves called the condition "dinga" or "dyenga", which derives from the Swahili phrase "Ki denga pepo" and meant a sudden strong cramp provoked by "bad spirits."

The first documented description of the disease was that made by Dr. Benjamin Rush in Philadelphia in 1780. Epidemics were reported almost simultaneously in 1779 and 1780 in Asia and Africa. The creation of the term "bone-breaking fever is attributed to Dr. Rush. In 1906 scientist Thomas Brancoft first identified the Aedes aegypti mosquito as the vector for dengue fever. In 1907, military physicians Percy Ashburn and Charles Craig proved that the agent that caused dengue fever was a virus transmitted by the Aedes aegypti mosquito.

The Aedes aegypti is a semi-domestic mosquito that lives in tropical regions and reproduces almost exclusively in artificial containers found in and around homes. The female feeds on human or animal blood and is seldom further than 100 meters away from the home. It deposits its eggs inside the containers; the eggs can endure dry conditions for a few months and then quickly hatch when the container again fills up with water.

Huge epidemics attributed to dengue fever took place in America, South Europe, North Africa, Asia and Australia during the early 20th century. In the 1950s and 60s the Pan-American Health Organization (OPS by its Spanish acronym) launched a campaign to eradicate the Aedes aegypti mosquito in order to prevent urban yellow fever, a disease that is also transmitted by this mosquito. As a result, dengue fever was almost eliminated, and in those decades only sporadic cases were reported in some Caribbean islands. The eradication program was gradually abandoned (it officially ended in 1970) and the Aedes aegypti once again infected the region. Today the mosquito has widespread distribution.

In the last 20 years, dengue fever epidemics have increased progressively in terms of frequency and size in most of the tropical countries in the South Pacific, Asia, Africa, Latin America and the Caribbean. The most dramatic increase in dengue fever as a huge public health issue has taken place in America. A large-scale epidemic occurred in Cuba in 1981 and a hemorrhagic dengue fever epidemic took place in Venezuela in 1989-1990. Since then, outbreaks have been reported in almost all tropical and subtropical countries in the Americas. Today Puerto Rico is undergoing an epidemic where up to 8,000 cases and five deaths have been reported this year.

The greatest challenge to conquer this disease centers on eradicating the mosquito through a combination of government, community and individual efforts. In addition, there is a big initiative to seek effective immunization in order to protect people against dengue fever. Last August one of the most promising vaccines began being tested in Puerto Rico and if successful it could be available in the market in the next few years.