ISSN 1020-6256

8 December, 1998

COMMUNICABLE DISEASES FEEDBACK REPORT

Reporting Period: Epidemiologic weeks 35 - 43, 1998

A Review of Selected Communicable Diseases

Acute Haemorrhagic Conjunctivitis (AHC)

Significant morbidity due to acute haemorrhagic conjunctivitis was observed in the sub-region between epidemiologic weeks 35 through 43, when 7,046 cases were notified. Major activity was recorded in Trinidad and Tobago [63.3%]; Antigua & Barbuda [19.6%]; Grenada [7.9%]; the British Virgin Islands [5.7%] and Montserrat [2.6%]. While the weekly mean number of reported cases of AHC during the first 35 weeks of 1998 was 34, excessive morbidity began to be observed in week number 36, when 262 cases were notified [see Figure 1]. Peak reporting occurred during week number 42 when 1,331 cases were recorded.

As at week number 43, ending October 31, 1998, a total of 8,145 cases have been reported for a sub-regional incidence rate of 123.3 cases per 100,000 population. During the corresponding period of 1997, only 1,130 cases of AHC were notified [see Table 1].

Of 38 eye swabs referred to CAREC’s virology laboratory from four CAREC member countries, enteroviruses were isolated from 23 or 60.5 percent of these samples [see Table 2],. These isolates have been characterised and confirmed by the US Centers for Disease Control and Prevention as coxsackievirus A 24.

Cholera

As at epidemiologic week number 43, twenty-one cases of cholera have been notified from Belize, the only CAREC member country in which cholera became endemic subsequent to its introduction into the Americas in 1991. It must be noted, however, that following the floods resulting from Hurricane Mitch, a cluster of five confirmed cases including one fatality was recorded in one village in the Cayo district. Use of creek water is suspected to have been the source of these infections.

Dengue Fever including Haemorrhagic and Shock Syndromes

During the epidemiologic period under review, 2,073 cases of classic dengue fever and 186 cases of haemorrhagic fever/shock syndrome were notified to CAREC’s Epidemiology Division. Roughly 51.0 percent [1,048/2,073] of the reported classical cases have been recorded in Jamaica, where dengue virus type 3 has been circulating indigenously. Trinidad and Tobago accounted for 46.7 percent [968/2,073] of the notified cases, while 53 cases due to type 4 infection were reported from the Bahamas during this period.

As at October 31, 1998, a cumulative total of 5,600 cases of dengue fever have been reported by CAREC member countries for an overall sub-regional incidence rate of 91 cases per 100,000 population [see Table 1; Figure 2].

A review of the dengue isolate profile based on specimens referred to CAREC’s laboratories during 1998, to date, indicates the exclusive circulation of dengue virus type 4 in the Bahamas; type 2 in Trinidad & Tobago and St. Vincent & the Grenadines; type 1 in Suriname and Antigua & Barbuda; and virus type 3 in Belize and Jamaica [see Figure 3]. Dengue virus type 2 has been circulating all year round, while pronounced activity due to types 4 and 3 has only occurred more recently [see Figure 4].

Note

Member countries are being reminded that deaths due to dengue fever and dengue haemorrhagic fever should be reported on the weekly communicable disease reports being submitted to CAREC’s Epidemiology Division, so that case-fatality rates could be calculated for the sub-region. Additionally, it must be emphasised that all of the following criteria must be present in a patient in order to make a clinical diagnosis of DHF:

Salmonellosis and Shigellosis

Significant increases in the cumulative totals of reported cases of salmonellosis and shigellosis have been noted during the year to date, as compared with the corresponding period of 1997. As at week number 43, 292 cases of salmonellosis and 145 cases of shigellosis have been cumulatively reported. Only 180 cases of salmonellosis and 81 cases of shigellosis had been notified during the corresponding period of 1997. Trinidad and Tobago, Barbados and St. Lucia each accounted for roughly 30.0 percent of the total cases of shigellosis reported during 1998.

Syphilis

During the period under review, 112 cases of syphilis were notified to the Epidemiology Division as compared with only 67 cases during the corresponding period of 1997. These cases were reported from 8 CAREC member countries. As at epidemiologic week number 43 of 1998, a cumulative total of 1,205 cases have been recorded for an overall sub-regional incidence rate of 20 cases per 100,000 population. Although annual reported syphilis incidence rates for the sub-region have declined significantly from a high of 115 cases in 1987 to 31 cases per 100,000 in 1997 [see Figure 5], careful monitoring of this trend is required. It is suspected that an increasing proportion of the population is accessing care for sexually transmitted diseases within the private health sector, and that such cases are not necessarily being captured by existing surveillance systems.

Tetanus

Although these numbers are small, it should be noted that a total of 12 cases of non-neonatal tetanus have been notified to CAREC’s Epidemiology Division for the year, thus far. All of these cases should, however, be viewed as avoidable. Every effort should be made to ensure that in addition to the routine vaccination of infants offered as part of national immunisation programmes, other initiatives should be adopted in order to increase immunity to tetanus in the wider population. One example of such strategy is the vaccination of persons attending chronic disease clinics as is appropriate.

In addition, it may be appropriate to suggest that tetanus vaccination strategies be reviewed within the context of disaster preparedness, as increases in nail stick injuries have been noted in two CAREC member countries affected by hurricanes in 1998.

Post-disaster Surveillance

As part of the PAHO Caribbean Disaster Response Team, CAREC personnel have been involved in the conduct of post-disaster surveillance in St. Christopher/Nevis following Hurricane Georges and in a post-disaster evaluation in Belize following Hurricane Mitch.

A review of the post-disaster surveillance data for St. Kitts/Nevis indicates that injuries were the major cause of morbidity as measured by visits to hospitals and outpatient facilities. It was estimated that over the period September 20-27, 1998, immediately following Hurricane Georges, 73.0 percent of the reported injuries (273/376) were hurricane related.

As regards Belize, surveillance for a number of diseases including dengue fever, cholera, malaria and Chagas disease must be intensified in view of the potential influx of displaced persons who may be expected to migrate from neighbouring Central American countries, affected by Hurricane Mitch.

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 is no unusual epidemiologic situation as regards malaria in the subregion. Guyana has only recently recommenced its weekly reporting of communicable diseases. The 1997 database would therefore not have contained any malaria reports from Guyana.
   
2. ARIs among under fives are not under surveillance in four CMCs.
   
3. Only five CMCs are currently reporting data on genital syndromes.
   
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, 12,158 cases of gastroenteritis have been cumulatively reported from that country during the first 9 months of 1998.
   
5. To date, AIDS Surveillance Reports for 1998 have been received from Trinidad & Tobago, Anguilla, Belize, St. Christopher/Nevis, the Turks & Caicos Islands and Suriname.