JEDDAH, 28 February 2003 — Seven cases of dengue hemorrhagic fever (DHF) have been detected in Jeddah, according to a source at the Jeddah Regional Laboratory.
“Seven Saudis — five males and two females — have come down with dengue fever. The disease is in its early stage. All the cases are under control and have been treated.”
The source said the mosquito-borne infection was not a byproduct of this year’s Haj as the victims were Saudis who did not perform the pilgrimage.
“The number of detected cases was small and therefore the situation is not considered dangerous,” he added.
Several DHF cases were detected in the Saudi town of Alkhorma, and as a result the virus has been named the Alkhorma virus. It was a severe form of DHF which has killed two people, the source said.
DHF was first recognized in the 1950s during the dengue epidemics in the Philippines and Thailand, but today DHF affects most Asian countries and has become a leading cause of hospitalization and death among children in several of them.
There are four distinct, but closely related, viruses that cause dengue. Recovery from infection by one provides lifelong immunity against that serotype but confers only partial and transient protection against subsequent infection by the other three. There is good evidence that sequential infection increases the risk of more serious disease resulting in DHF.
The global prevalence of dengue has grown dramatically in recent decades. The disease is now endemic in more than 100 countries in Africa, the Americas, the Eastern Mediterranean, Southeast Asia and the Western Pacific. Southeast Asia and the Western Pacific are most seriously affected.
Some 2.5 billion people are now at risk from dengue. WHO estimates there may currently be 50 million cases of dengue infection worldwide every year.
The spread of dengue is attributed to expanding geographic distribution of the four dengue viruses and of their mosquito vectors, the most important of which is the predominantly urban species Aedes aegypti.
A rapid rise in urban populations is bringing ever greater numbers of people into contact with this vector, especially in areas that are favorable for mosquito breeding, for example where household water storage is common and where solid waste disposal services are inadequate.
Dengue viruses are transmitted to humans through the bites of infective female Aedes mosquitoes. Mosquitoes generally acquire the virus while feeding on the blood of an infected person.
