On 23/09/1414H, the Ministry of Health was alerted to two confirmed cases of dengue acquired in Jeddah. One was in an adult Saudi male with grade 2 dengue hemorrhagic fever (DHF) and the other in an adult Saudi male with dengue shock syndrome (DSS). Dengue 2 virus isolated from one patient was similar to strains of dengue 2 from East Africa.
During week 10 of 1994 (24'09/1414H) all hospitals and clinics in Jeddah were alerted and asked to report suspect cases of dengue hemorrhagic fever (DHF). Six weeks later they were reminded about reporting and sent a case definition for DHF: fever with thrombocytopenia or leukopenia plus the following: bleeding, skin rash, eye pain, joint pain and headache. Dengue symposia for Jeddah clinicians were presented on weeks 16, 23 and 27. During week 21 (16/12/1414H), surveillance was expanded to include simple dengue fever (DF) in addition to DHF and DSS. The suspect DF case definition was as follows: fever and two or more of the following symptoms: frontal headache, myalgias or arthralgias, retro-orbital pain, skin rash or bleeding.
For each suspect DF case, the Dengue Control Team interviewed the patient about possible exposures and dengue symptoms in household contacts. Blood specimens were collected for isolation of dengue virus and for detection of anti-dengue IgM and IgG. Virus isolation and serology were done at the Virology Department of Dr. Suleiman Fakeeh Hospital, Jeddah. A confirmed case was defined as a suspect case of DF or DHF or DSS with either isolation of dengue virus from blood or anti-dengue IgM detected from the serum.
This surveillance system detected suspect DF every week from week 13 to week 36, and half of these were confirmed (Figure 1). There have been no deaths from DF. One additional DHF case was detected in week 13. Increases in confirmed DF occurred in week 16 and week 22, following improvement in the case definition and reminders about reporting. Thirty-nine percent of both confirmed and suspect DF was in construction workers. Confirmed DF in other persons was more common in new districts of north Jeddah and southeast Jeddah, where new house construction is more common. Currently, the Dengue Control Team is evaluating the role of new house construction in the propagation of dengue vectors and dengue virus.
Entomologic survey: The Malaria Department carried out a survey for dengue vectors beginning on 24/09/1414H. Aedes aegypti was found in Ruwais, Bawadi, Sulaimania, and Kilo 7 districts. Aedes albopictus was also found in these districts plus Biutat, Rawda and Nuzha districts.
Editorial note:
Prior to the identification of dengue 2 from Jeddah, dengue 2 transmission had been confirmed from Somalia, Port Sudan, Djibouti and Yemen. The similarity of the dengue 2 virus isolated from the index case to the East African strains of dengue 2 suggests that dengue was introduced from one of these areas.
The control of dengue in western Saudi Arabia will rest on continued and improved surveillance. The dengue surveillance system has successfully identified high-risk groups (construction workers) and high-risk areas to be targeted for control. It has shown the rarity of severe disease and is keeping clinicians informed of the continuing probability of dengue in febrile patients.
Continuing surveillance will be needed to monitor the effectiveness of control.
Physicians should identify and report suspect dengue. In older children and adults, DF presents with fever (38C), prominent myalgias, arthralgias and retro-orbital headache with pain on eye movement. The fever tends to be biphasic. A transient rash sometimes appears during the first two days of fever and a generalized morbilliform rash often appears during the second fever elevation. Other characteristic symptoms include taste aberrations, other sensory phenomena and a conjunctival suffusion. In young children, dengue usually presents only as an undifferentiated fever. DI-IF and DSS occur both in children and in adults. DHF cases will have a positive tourniquet test, thrombocytopenia and hemoconcentration. DSS cases will have hypotension, a narrow pulse pressure, thrombocytopenia and hemoconcentration with or without signs of bleeding. DF, DHF or DSS are confirmed by isolating dengue virus from the patient's blood or detection of anti-dengue IgM in serum taken within 3 weeks of the onset of fever. Physicians should identify and report suspect den cases; assistance will be provided for confirmation.
