In November 1999, Suriname began to experience an increase in morbidity due to dengue fever and dengue haemorrhagic fever (DHF), above what was expected for that time of year. This epidemic is still continuing in 2000, though based on reports from the Bureau of Public Health in Suriname, the rate of new infections appears to be decreasing. In November 1999, CAREC's lab confirmed the virus type in samples from 8 patients to be DEN-2. In 1999 there were 666 hospital admissions for dengue, compared to 460 admissions for dengue in 1998, representing a 50% increase in admission in 1999. Also, there have been 7 reported deaths due to dengue in the 1999/2000 epidemic to date, compared only 1 reported death due to dengue in 1998. While cases were not classified as dengue fever or DHF, the increase in hospital admissions and deaths would suggest an increase in the number of severe cases for the 1999/2000 epidemic compared to that in 1998. This is not surprising since DEN-1 was identified as the main virus type circulating in 1998, DEN-2 is circulating in 1999/2000 and sequential infections with different serotypes is a known risk factor for severe disease.

Venezuela is still under a nationwide alert, which was declared by health authorities on December 27, 1999. The Epidemiology Director has said that this alert will remain in place for several months, given the current situation. The epidemic is concentrated in the western states of Zulia and Falcon. In 2000, there were 545 cases of dengue fever reported from Zulia and 292 cases reported from Falcon.

On January 14, 2000, the French National Institute for Public Health Surveillance (CIRE/InVS) confirmed the isolation of DEN-3 in French Guyane for the first time. Four (4) cases of DEN-3 of autochtonous transmission were confirmed in December 1999 by the Institute Pasteur de Guyane. During 1999, DEN-1 and DEN-2 were also circulating in French Guyane.

Transmission of the dengue virus can only be reduced by effective control of the vector, namely the Aedes aegypti mosquito. Communities must be involved in mosquito habitat search and destroy activities. It is also important that laboratory-based surveillance is enhanced to facilitate the identification of circulating serotypes.

In the absence of an effective vaccine, travellers to infected areas are advised to take the following measures, particularly during the day, to prevent mosquito bites:

Yellow Fever – Brazil

On January 24, 2000, the WHO reported 61 suspected cases of yellow fever from Brazil for the year to date. Of these, five (5) were laboratory confirmed, 8 discarded and 48 are pending laboratory results. Of the confirmed cases, one (1) was reported from the State of Rio de Janeiro (Rio de Janeiro County) and two (2) were reported from the State of Sao Paulo (Sao Paulo City and Campinas counties). These three (3) cases were all infected in the State of Goiás (Alto Paraíso County), as were two (2) confirmed cases from Brazil reported in late December 1999. The other two (2) confirmed cases for 2000 were reported from the State of Goiás (Doverlândia and Goiás Velho Counties). Both these cases died. All five (5) confirmed cases reported in 2000 are due to sylvatic (acquired in a jungle location) transmission of the yellow fever virus and there is no evidence of urban transmission.

Active surveillance and vaccination campaigns are currently underway throughout the country. The goal is to extend vaccination coverage in endemic areas to 95 % of the population.

As stated in the previous Fax Alert of November, 1999, please be reminded of the vital importance for all travellers to be vaccinated against yellow fever at least 10 days before visiting endemic areas. While vaccination is the preferred method for the prevention and control of yellow fever, the strengthening of Aedes aegypti control programmes by source (habitat) reduction activities is also a key factor in the prevention of urban yellow fever outbreaks.

Physicians in CAREC member countries should also maintain a high index of suspicion for unidentified fevers and record patients travel history.

Influenza testing in the Caribbean

The influenza crisis in Europe and North America has been caused by a particularly virulent strain, A[H3N2], more commonly known as Australian Flu or Sydney H3N2. While this is one of the strains used in the flu vaccine for the 1999/2000 season, immunisation campaigns have not achieved their targets in many countries, as most countries did not cover their target groups very well.

With high levels of travel between the Caribbean, Europe and North America, this is also the flu season for CAREC member countries and some countries have been reporting levels of influenza morbidity above that expected for this time of year.

Influenza testing can now be done at CAREC’s virology laboratory. Samples sent for testing should be either nasal aspirates or nasal swabs of less than 72 hours, from uncomplicated patients >5 years, with symptoms fitting the case definition for influenza. CAREC’s laboratory can be contacted at 868-628-1032, should you have any queries.