1997 Weeks 25-44

Communicable Diseases Feedback Report

Reporting Period: Epidemiologic Weeks 25-44, 1997

A Review of Selected Communicable Diseases

Dengue Fever and Dengue Haemorrhagic Fever

Although the overall reported dengue fever morbidity for the region in 1997 is significantly reduced when compared with the situation in 1996 (Figure 1), notable activity has been documented in Belize, Barbados and Trinidad and Tobago, including the occurrence of haemorrhagic cases in the latter two member countries.

During the first forty-four weeks of 1997, one thousand one hundred and one (1,101)( cases of classical dengue fever have been formally notified to CAREC’s Epidemiology Division as compared with 4562 cases which had been reported during the corresponding period of 1996 (Table 1). While in 1997, the greatest proportion of classical cases (71.2%) has been notified from Trinidad and Tobago, classical dengue fever has been recorded in seven other CAREC member countries, including 183 cases from Belize. In addition, discussions with the Ministry of Health in Barbados indicate the occurrence of a significant outbreak of dengue fever in that country with haemorrhagic cases and four deaths. As at November 22, 1997 (epidemiologic week number 47), 872 suspected cases of dengue fever had been documented there.

During the same period, 48 (suspected cases of haemorrhagic dengue fever have been formally notified as compared with no case reports for the previous year. To date, all of the reported cases of haemorrhagic dengue have been recorded in Trinidad and Tobago, where one fatality has also been documented.

Both in Trinidad and Tobago and Barbados, dengue virus type 2 has been the predominant aetiologic agent circulating during 1997. It is important to note, however, that significant outbreaks of dengue fever due to the type 1 virus had been recorded during 1995 and 1996, in Barbados and Trinidad and Tobago, respectively. Additionally, dengue virus type 3 has been identified in Belize in 1997.

The occurrence of documented cases of haemorrhagic dengue fever with deaths is therefore not an unexpected phenomenon either in Trinidad and Tobago or Barbados since these two populations have been sequentially exposed to dengue virus types 1 and 2, within a very short period of time.

Given that dengue virus type 2 appears to be hyperendemic in some of our member countries and that the possibility of introduction of the type 3 virus is real, CAREC wishes to strongly advise its member countries of the following:

Effective and active surveillance of human cases presenting with febrile illness and other signs and symptoms compatible with a diagnosis of dengue fever must be intensified at both the district, regional and national levels.

Ministries of Health should have in place contingency plans to handle the increased demand for hospital beds, including those for intensive care, which would arise if large numbers of cases of Dengue Haemorrhagic Fever (DHF) and Dengue Shock Syndrome (DSS) began to occur.

Physicians and other health care providers must be sensitised to the diagnosis and effective management of DHF/DSS in order to prevent avoidable deaths and the required infrastructure to ensure appropriate clinical monitoring must be provided.

Aggressive control and surveillance of the Aedes aegypti vector are essential if dengue fever is to be controlled and prevented. While routine mosquito containment measures may be adequate during non-epidemic periods, during periods of increased dengue activity, intensive vector control efforts linked to the occurrence of cases are necessary. An integrated and cohesive strategy is therefore imperative.

Education of the entire community as regards its very important role in the control and elimination of the vector, as well as the development of meaningful health promotional and preventive perspectives for sustained disease prevention need to be intensified.

The public should also be advised of those personal protective measures which could be taken in order to reduce transmission from infected persons. These would include the use of appropriate insect repellants; the wearing of long-sleeved clothing and long pants during peak mosquito biting times; the spraying of bedrooms with insecticide before going to bed; and the use of mosquito netting over beds, where bedrooms are not air-conditioned or screened.

In order to ensure the long-term sustainability of dengue prevention and control measures from a population perspective, Ministries of Health are being encouraged to actively forge partnerships with all sectors of the media, community groups, environmental agencies and other relevant groups.

Measles

During the period under review, 310 suspected cases of measles were reported from 13 countries to CAREC through the enhanced Measles Elimination Surveillance System (MESS) of the Expanded Programme on Immunisation. Roughly one third of all reported cases were recorded in the Bahamas. Seventy-nine percent of all cases were collectively notified from the Bahamas, Guyana, Jamaica and Trinidad and Tobago. No suspected case has been laboratory confirmed as measles during this period. Cumulatively, therefore, 908 suspected cases have been reported to CAREC during 1997, a figure that is significantly higher than the 385 recorded during the corresponding period of 1996 (Table 1 & Figure 2).

Rubella and Congenital Rubella Syndrome

One hundred and nine cases of rubella were reported to CAREC’s Epidemiology Division during the period, week numbers 25 through 44 of 1997. As at the end of epidemiologic week number 44, a total of 491 cases of rubella have been recorded in 1997, as compared with 472 cases during the corresponding period in 1996 (Figure 3). The increased rubella activity of 1996 continued to be observed during the first two months of 1997, waning thereafter. Trinidad and Tobago accounted for the greatest proportion, 49.8 percent, of cases recorded to date in 1997, while Guyana contributed 19.3 percent of total cases.

A review of the MESS database indicates that 275 of the 908 suspected cases of measles referred for laboratory diagnosis from 16 CAREC member countries were confirmed as rubella (Table 2).

Seventeen cases of congenital rubella syndrome (CRS) have been recorded during the first 44 weeks of 1997 as compared with 8 for the corresponding period of 1996. These cases have been documented in Jamaica (6), Trinidad and Tobago (4), Belize (3), Barbados (2), Guyana (1) and Suriname (1). The maternal ages of these cases of CRS ranged from 18 to 37 years with a mean and median of 25.0 and 24.0 years, respectively.

The maternal age distribution of these CRS cases support the hypothesis that we have not as yet increased our rubella vaccination coverage among women of child bearing age to prevent the occurrence of CRS and our use of the measles-mumps-rubella vaccine has been too recent to derive any significant benefit against CRS from infant vaccination strategies. It should also be noted that the occurrence of many of these cases of CRS have resulted from missed opportunities immediately post-partum as well as post-natally as many of these mothers are multiparous. Efforts should be made to identify and vaccinate any age specific susceptible population cohorts.

Outbreak Corner

Acute Haemorrhagic Conjunctivitis: Belize Belize has notified us of the occurrence of an outbreak of acute haemorrhagic conjunctivitis (AHC) which began in October 1997 and peaked in November, when 565 cases were recorded. The greatest proportion of cases (40.6% or 473/1164) was in the age group, 15 –34 years, and males and females were equally affected. The cause of this outbreak is unknown at this time.

During the first forty-four weeks of 1997, CAREC had been requested to provide technical assistance to a number of its member countries in the area of outbreak investigation, control and management. The following is a brief outline of these epidemiologic situations and the important lessons to be learned:

Gastroenteritis: Antigua and Barbuda An outbreak of gastroenteritis due to rotavirus was recorded in Antigua and Barbuda during the first two months of 1997. From the investigative findings, it was estimated that about 4,000 cases might have actually occurred, half of them having been detected and reported via the Ministry of Health, with another half having been seen by private medical practitioners and pharmacists.

The Lesson: Surveillance systems must of necessity include physicians, laboratories and other health care providers in the private health sector, if a Ministry of Health is to have accurate morbidity and mortality data to effectively and efficiently guide its public health response.

Malaria: The Cayman Islands A small outbreak of malaria occurred in the Cayman Islands involving three cases, whose locally acquired infections were linked to an imported case.

The Lesson: All countries, especially those from which malaria has been eradicated, need to ensure that effective surveillance mechanisms and procedures are established and are well known to all physicians so that imported cases of malaria can be diagnosed and treated early; nursed under appropriate conditions; and investigated thoroughly, including a search for additional local infections that may result from the imported case. Such systems, inclusive of components for anopheline vector surveillance, are of particular importance in those countries which have a high influx of immigrants from malaria endemic areas.

Viral Hepatitis A: The Bahamas An increase in the numbers of laboratory confirmed cases of viral hepatitis A being notified from the Bahamas was observed in June, 1997. However, from the epidemiologic investigation, it was noted the majority of cases were young children. Review of hospital admission registers and other data however indicated that cases had onsets of illness in as early as January 1997, and that there had been significantly more admissions to the paediatric service of the Princess Margaret Hospital presenting with jaundice during the first six months of 1997 when compared with the 1996 situation.

The Lesson: Control measures for hepatitis A infection must, of necessity, be community-wide, and cannot be limited to those individual households in which known cases have been documented, as many infections, especially among children, are asymptomatic. Additionally, Ministries of Health must engage other ministries and sectors in improving public health amenities (safe water supplies; sanitary disposal of sewage) in under-served areas.

Tuberculosis: St. Christopher and Nevis Between January and June 1997, eleven cases of tuberculosis were notified to the Ministry of Health in St. Christopher/Nevis, a situation in marked contrast to the preceding three years when 1, 5 and 3 cases had been reported annually in 1994, 1995 and 1996, respectively. The Lesson: The management of all national tuberculosis control programs needs to be strengthened as tuberculosis re-emerges as a public health problem in the subregion, this situation being exacerbated by the HIV epidemic. Diagnostic and treatment guidelines following the WHO and CAREC recommendations ( CAREC’s Tuberculosis Manual of Prevention and Control Procedures, 1977) must be widely disseminated to all health care providers in order to ensure standardised practice. Appropriate management must also include the close monitoring of patients on therapy. The continuing education of all members of the health team is imperative, including an orientation to the prevention of nosocomially spread tuberculosis.

A General Lesson While we recognise the difficulties that many of our member countries, for whom tourism is a major foreign exchange earner, face when there is an outbreak of a communicable disease, especially one that is spread via the faecal-oral route, we must still strongly advise the immediate implementation of appropriate control and preventive measures, even if such measures must include the use of the public media for education of the population, etc.

A General Comment

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

Chlamydia infection was reported from seven CMCs in 1997 as compared with four in 1996. Malaria data from Guyana for 1996 and 1997 have not been included in the subregional database, as weekly totals could not be ascertained. However, 34, 075 cases of malaria were notified from Guyana in 1996. ARIs among under fives are not under surveillance in four CMCs. Only five CMCs are currently reporting data on genital syndromes. Data on gastroenteritis from Trinidad and Tobago is not age-categorised, and has therefore been excluded from the subregional totals.