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2001 Weeks 1-12 |
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ISSN 1020-6256 CARIBBEAN EPIDEMIOLOGY CENTRE [CAREC]COMMUNICABLE DISEASE FEEDBACK REPORTA Quarterly Review Of Selected Diseases:-
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During the first quarter of 2001, epidemiologic weeks 1-12, 653 cases of dengue fever were reported to CAREC’s Epidemiology Division from eight CAREC member countries [Appendix 1; Figure 1], resulting in an incidence rate of 10.6 cases per 100,000 population. This represents a forty-nine percent decrease in reported cases during the corresponding period in 2000 [Figure 1]. The largest contributors to the 653 cases reported in the first quarter of 2001 were Trinidad and Tobago [60%] and Barbados [33%]. Thirty-one cases of dengue haemorrhagic fever/shock syndrome were reported during the period under review, thirty cases from Trinidad and Tobago and one from Suriname. This represents a three-fold increase in reported cases from Trinidad and Tobago compared to the same period last year.
During the first quarter of 2001, CAREC’s laboratory identified dengue virus types 1, 2 and 3 from samples received from member countries [Table 1]. Dengue virus type 2 was confirmed in fifteen out of fifty-seven samples received from Guyana.
Influenza And Acute Respiratory Infection Among < 5 Year Olds The sub-region experienced a relatively mild 2000 - 2001 influenza season. During the period under review, 16,545 cases of influenza were reported to CAREC’s Epidemiology Division, resulting in a rate of 298 cases per 100,000 population, compared to the corresponding period last year when the rate was 325 cases per 100,000 population. However, six countries reported more cases of influenza during the first 12 weeks of this year compared to the corresponding period last year, in Trinidad and Tobago there was a 35% increase in morbidity due to influenza, in Antigua & Barbuda there was a 247% increase, in Bermuda a 43% increase, in the British Virgin Islands a 183% increase, in Montserrat a 269% increase and in St. Vincent and the Grenadines there was a 29% increase. In these six member countries, influenza activity peaked later in the 2000-2001 season than during the 1999 - 2000 influenza season. For example, in the 2000 - 2001 influenza season in Trinidad and Tobago, the peak activity occurred during weeks 9 - 12 compared to in the USA where activity peaked during weeks 3-6.
To date, there was no available information about the type of influenza virus circulating in the Caribbean, however influenza A (H1N1) viruses predominated in North America and Europe during the period under review.
During the period under review, there was a 55% percent reduction in the total number of reported cases of acute respiratory infection among children under five years of age compared to the corresponding period last year. This was mostly due to non-reporting from Guyana, who reported 51% of the acute respiratory infections among those under five years old in the first quarter of 2000. However, during the period under review, four member countries who reported increased numbers of cases of influenza also reported increased numbers of cases of acute respiratory infections among the under five years olds compared to the first quarter of last year, Antigua had 29% increase, Bermuda had a 133% increase, Montserrat had a 37% increase and St. Vincent and the Grenadines had a 43% increase.
The Public Health Laboratory Information System Network [PHLIS] During the period under review, eight member countries reported eight positive Salmonella samples to CAREC through the PHLIS network [Table 2]. Of these, two Salmonella group B samples reported from Jamaica were from the same household.
Three member countries reported twenty-seven samples that were positive for dengue through the PHLIS network, nineteen from Trinidad and Tobago, seven from Suriname and one from Grenada [Table 2]. These were all confirmed by IgM serology, but serotypes were not identified. Of these twenty-seven samples, nineteen were from patients who had been hospitalized, four having been diagnosed with dengue fever with haemorrhagic manifestations and three with dengue haemorrhagic fever/shock syndrome.
During the period under review, of the two member countries using the PHLIS HIV/AIDS module, one country reported two HIV positive samples from adults [Table 2].
Meningococcal Infections in Trinidad and Tobago
During the first quarter of 2001, six cases of meningococcal infection were notified to CAREC’s Epidemiology Division from Trinidad and Tobago, five of which were fatal, resulting in a case fatality rate of 83%. Five of these six cases were laboratory confirmed as Neisseria meningitidis serogroup B by culture and were identified as part of the same electrophoretic type-5 complex. The sixth case was confirmed by post mortem examination and was also epidemiologically linked to a laboratory confirmed case. One case was aged less than five years old, three cases were between the ages of 5-14 years and two cases were in the age group 15-24 years. Four of the six cases were reported from the county of St. George West and two were from the county of St. Andrew/St. David.
Since 1997, there has been an increase in the number of meningococcal infections reported from Trinidad and Tobago to CAREC’s Epidemiology Division [Figure 2]. This has often been mirrored by increases in reported cases of meningitis [Figure 3].
During the period January 1998 to the end of epidemiologic week 12 of 2001, a total of forty-six cases of meningococcal infection have been reported to the Trinidad and Tobago Ministry of Health. Of these forty-six infections, forty were confirmed by laboratory culture, four were confirmed by post-mortem examination (of these three were also epidemiologically linked to a laboratory confirmed case) and two were confirmed by epidemiological linkage to a laboratory confirmed case. Forty-one of the forty-six infections were classified as cases of meningococcal meningitis and the five were asymptomatic carriers. The overall case fatality rate was 41%, but the highest case fatality rate was observed among those aged 5-14 years [Table 3]. Neisseria meningitidis was isolated from forty samples, thirty-five of these were identified as serogroup B, two were serogroup A and three were ungrouped. Thirty-two of the thirty-five serogroup B samples were identified as part of the electrophoretic type-5 complex.
Plasmodium malariae Infection In Trinidad
In 2000, twelve cases of Plasmodium malariae were reported from Trinidad. The symptomatic index case was identified as a hunter who had visited a forest in the southeast of the island. Active case detection resulted in the identification of a further eleven cases, eight adults (between the ages of 23-74 years) and three children (aged between 3 and 14 years), all of whom either worked or resided in forested areas of southeast Trinidad.
A similar outbreak of P. malariae, a parasite characterized by its long chronicity in man, was observed during 1994-95 in the same region of Trinidad, 30 years after a successful eradication program. The vector involved in this autochtonous transmission was probably Anopheles bellator, a sylvatic mosquito breeding in bromeliads, and found in high density in the forest surrounding human habitats of this part of the island.
Pertussis outbreaks in Guyana, Suriname and French Guiana During the first quarter of 2001, two outbreaks of Pertussis occurred among Amerindian communities of the interior of Guyana, Suriname and French Guiana. In Guyana, an outbreak of Pertussis was observed among the Wai wai Communities of Region 9, which borders Brazil. During week 11, five symptomatic cases were investigated by a Ministry of Health team and CAREC’s laboratory identified Bordatella pertussis from nasopharyngeal swabs from two of these cases. Retrospective analysis showed that the outbreak started early in 2001, in remote settlements located in the area bordering the Brazilian state of Roraima .The second outbreak affected the Wayana communities along the upper-Maroni river, on the border between Suriname and French Guiana. During weeks 13-17, thirty-three cases, including one death were reported from seven different Amerindian villages. Two of these cases were laboratory confirmed and the others were confirmed on the basis of epidemiologic linkage.
The Ministries of Health of these countries reported very low immunization coverage (50% or less) for Pertussis among the Amerindians Communities of the Interior. The response in both outbreaks was emergency immunization of the unvaccinated or incompletely vaccinated children under seven years of age, additionally erythromycin was given to suspected cases and contacts.
Viral Hepatitis A In The Bahamas
During epidemiologic weeks 2-9, 2001, an outbreak of Hepatitis A occurred in a pre-school in the Bahamas. Twenty-five cases were reported in total, but investigations by the Ministry of Health, Bahamas did not identify the source. However, the outbreak is over, as there have been no further cases reported from this school since week 9.
General Comments Regarding Appendix 1
The data presented in Appendix 1 of this report should be interpreted with the following in mind:
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Caribbean Epidemiology Centre
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