During 1998, a cumulative total of 6,678 cases of dengue fever were reported for an annual, sub-regional incidence rate of 101 cases per 100,000 population. These 1998 notifications represented a 1.7 fold increase over the 3,940 cases registered during the previous year. In 1998, the highest incidence rates were recorded in Barbados, Suriname, Trinidad and Tobago, the Bahamas, St. Vincent & the Grenadines and Jamaica [Table 2]. When compared with the 1997 reports, increased morbidity was observed in Trinidad and Tobago [1.5 fold]; St. Vincent & the Grenadines [6 fold]; Suriname [13 fold] and Jamaica [78 fold] during 1998.

A review of the isolate profile for 1998 indicates that all four dengue serotypes were circulating within the sub-region during the year, although Barbados was the only country from which all four virus types were recovered [Figure 2]. Dengue virus type 1 was exclusively identified in Suriname, St. Lucia, Haiti, Dominica, and Antigua/Barbuda, while virus type 2 was the sole agent isolated in Trinidad & Tobago and St. Vincent & the Grenadines. Dengue virus type 4 was the only agent confirmed in the Bahamas and the Dominican Republic. Dengue virus type 3, which had been identified for the first time in Belize during 1997, accounted for 97.0% of the isolates in Jamaica and was the only serotype isolated in Belize and St. Christopher /Nevis during 1998.

It must be noted that a significant proportion of the Caribbean population is susceptible to DEN-3, as previous to 1997, this type had last been documented in the region during 1978 [Fax Alert dated November 30, 1998].

Note

We would like to recognise receipt of detailed statistical data, for the first time, on dengue fever, dengue haemorrhagic fever/shock syndrome and yellow fever from the French Overseas Departments of Martinique, Guadeloupe and French Guyana. While these territories are not CAREC member countries, they are a strategic part of the sub-region and have therefore indicated their willingness to collaborate with us and to participate in regional communicable disease surveillance activities. These collaborative linkages are not new, but represent an expansion in those linkages that have already been forged between these French Departments and the Expanded Programme on Immunisation.

In 1998, the patterns of dengue fever in the French Overseas Departments differed markedly from one territory to another [Figures 3 and 4]. In Martinique and Guadeloupe, where physician sentinel networks facilitate the early detection of outbreaks, annual incidence rates of 312 and 170 suspected cases per 100,000 population were recorded in those respective territories. Such rates were similar to those of neighbouring countries. In contrast, however, annual incidence rates of 1880 suspected cases per 100,000 population and 405 IgM confirmed cases per 100,000 population, were recorded in French Guyana, which has an ecosystem similar to that of Northern Brazil. These rates were significantly higher than those documented for any of the CAREC member countries.

During 1998, three dengue fever serotypes were isolated in the French Overseas Departments. Both virus types 1 and 2 were isolated in Martinique and French Guyana, but DEN-2 was the sole aetiologic agent responsible for the outbreaks in Martinique between July and December and in St. Laurent du Maroni, French Guyana [bordering Suriname], between March and October. In Guadeloupe, while virus types 1, 2 and 4 were isolated during the year, 95% of all the isolates were DEN-1.

Yellow Fever

While no cases of yellow fever were notified from any CAREC member country during 1998, it is important to note the occurrence of sylvatic cases of yellow fever with deaths in three neighbouring countries of Venezuela, Brazil and French Guyana. In Venezuela and French Guyana, cases were documented among Amerindian communities, the Yanomami and Wayana, respectively [Fax Alert dated October 23, 1998; French Weekly Epidemiologic Record: 39 of 1998]. These cases resulted from an epizootic wave affecting the rain forest ecosystem of the Guyana’s highlands, which includes the interior of Guyana as well as that of Suriname. This pattern of transmission requires careful monitoring as the possibility of long distance spread within a limited period of time is real. Furthermore, high Aedes aegypti infestation along coastal and riverine settlements in these countries greatly increases the risk for urban transmission of yellow fever.

Acute Haemorrhagic Conjunctivitis [AHC]

Commencing in epidemiologic week number 36 of 1998, a significant increase in reported morbidity due to acute haemorrhagic conjunctivitis [also known as "red eye"] was observed in the sub-region. During the period under review, 4,592 cases were reported, as compared with 293 cases during the corresponding 1997 period. Trinidad and Tobago accounted for the greatest proportion of case notifications [91.3% or 4,193 cases].

During 1998, a total of 12,795 cases of AHC were recorded in the sub-region, resulting in an overall incidence rate of 207.4 cases per 100,000 population. While most of the reported cases [72.0% or 9,213 cases] were registered in Trinidad and Tobago, the highest annual incidence rate, of 3,105 cases per 100,000 population, was recorded in the British Virgin Islands. During 1998, cases of AHC were also reported from Antigua and Barbuda, the Bahamas, Grenada, Dominica, Montserrat, St. Christopher/ Nevis and the Turks and Caicos Islands.

Cholera

During 1998, 29 cases of cholera were reported from Belize, 8 of which were notified during the period under review. While Belize is the only CAREC member country in which cholera is endemic, following Hurricane Mitch, several cases and deaths due to cholera occurred in many other Central American countries, namely El Salvador, Guatemala, Nicaragua and Honduras.

Rubella and Congenital Rubella Syndrome

During the period under review, only one case of rubella was notified in the sub-region and that from Trinidad and Tobago. However, during the corresponding period in 1997, 91 cases were reported from 6 different countries, with 73% of these cases being recorded in the Cayman Islands. Forty-seven cases of rubella were reported during 1998 as compared with 603 in 1997. It should be noted however that during 1998, 99 suspected cases of measles referred through the enhanced measles surveillance system [MESS] were laboratory confirmed as rubella. Although 90.0 percent of these confirmed rubella cases were identified in Suriname, cases were also documented in the Commonwealth of the Bahamas, Belize and Guyana.

No cases of congenital rubella syndrome were reported during the period under review. Cumulatively, however, there were 7 case reports in 1998, 4 from Bahamas and 3 from Jamaica. At the recently concluded meeting of Caribbean EPI Managers, which was held in Grenada in December 1998, a decision was taken to narrow the focus of CRS surveillance to infants less than 12 months of age. Data from the regional CRS surveillance system that was established during 1996, indicates that roughly 90.0 percent of the reported cases were diagnosed within the first year of life.

While this change is expected to impact somewhat on the quantification of incident cases of CRS, the primary purpose of CRS surveillance is to document the occurrence of CRS as an indication of recent rubella virus circulation and to identify gaps in the national and regional rubella elimination strategies.

A GENERAL COMMENT CONCERNING TABLE 1

Any interpretation of the data presented in Table 1 of this report should be undertaken with the following in mind:

1. There was no unusual epidemiologic situation as regards malaria in the sub- region. Guyana had only recently recommenced its weekly reporting of communicable diseases and, hence, the 1997 database would not have contained any malaria reports from Guyana.
2. ARIs among under fives are not under surveillance in four CMCs.
3. Only five CMCs reported data on genital syndromes during 1998. Jamaica, our largest member, commenced routine reporting of genital syndromes in 1998.
4. Data on gastroenteritis from Trinidad and Tobago is not provided in an age-categorized format, and have therefore been excluded from the age-specific sub-regional totals. However, 14, 109 cases of gastroenteritis have been cumulatively reported from that country during 1998.
5. To date, no AIDS Surveillance Reports for 1998 have been received from Trinidad & Tobago, Anguilla, Belize, St. Christopher/Nevis, the Turks & Caicos Islands and Suriname.

During this reporting period, no weekly communicable disease reports have been received from Anguilla, Suriname, Aruba or the Netherlands Antilles.

Dr. MJ Lewis, Dr. E. Boisson, Dr. S. Aldighieri and Team