 |
2000 Weeks 1-12 |
|
|
ISSN 1020-6256 MAY 2000
COMMUNICABLE DISEASES FEEDBACK REPORT Review Period: Epidemiologic Weeks 1-12 of 2000 A Review of Selected Diseases
Dengue Fever During the first quarter of 2000, 563 cases of dengue fever were formally reported to CAREC’s Epidemiology Division, for a sub-regional incidence rate of 10.4 cases per 100,000 population [Table 1; Figure 1]. It is recognised, however, that these data underestimate the true extent of current morbidity, as an outbreak had been occurring in Suriname, from which no formal communicable disease reports have been received at this time. From our current data, however, it was noted that morbidity reports from two countries, namely, Barbados and Grenada, were significantly higher in this quarter as compared with the data recorded during the corresponding period of 1999. For example, 291 cases of dengue fever were notified from Barbados during this quarter, representing an increase of 116% over notifications for the same period in 1999 [Figure 2]. A review of Suriname’s national Epidemiologic Bulletin [dated March 2000] indicates that between January 1st and March 17th, 2000, 553 cases of dengue fever were notified via their hospital surveillance, while 752 cases were recorded through their "telefonade" surveillance system during the first eight weeks of the current year. Hence, Suriname would represent a third CAREC member country [CMC] in which reported dengue fever morbidity for the first quarter of 2000 was significantly higher than that for the corresponding period of 1999.
During the period under review, Trinidad and Tobago was the only CMC, from which dengue haemorrhagic fever/ dengue shock syndrome [DHF/DSS] was formally notified, as 10 cases were recorded during the first quarter of 2000. A review of CAREC’s laboratory data indicates that 27.0 percent of the 515 patients referred for laboratory diagnosis of dengue fever during the first quarter of 2000 were confirmed as positive. One hundred and eight (108) patients were confirmed on the basis of IgM serology, while another 31 patients were identified through virus isolation or the polymerase chain reaction [PCR] assay. At least three dengue serotypes have been circulating in member countries during the period under review [Table 2]. Referrals to CAREC’s laboratories for confirmation of dengue virus infection originated from 15 member countries. During this quarter under review, the national health authority in the British Virgin Islands informed us of the occurrence of two positive cases of dengue fever, which were confirmed by the CDC’s Dengue Branch Laboratories in Puerto Rico. Both of these cases had onsets of illness in February 2000. One case, a 4-month old child had presented with clinical signs and symptoms that were compatible with a diagnosis of DHF, Grade 11, while the other case, a 23-year old female, had developed fever, ecchymoses and thrombocytopenia.
Influenza & Acute Respiratory Infections among Under Fives There was a roughly 28.0 percent decline in reported influenza morbidity during this quarter under review as compared with the corresponding period in 1999. Significant reductions in case reports were noted in six member countries [Figure 3a]. However, while this overall trend was observed, some countries did experience increased reports of cases of influenza. For example, increases in the order of 24.0 and 19.0 percent were recorded in the Bahamas and Trinidad and Tobago, respectively. During this review period, a 58.0 percent reduction in reports of acute respiratory infections among children under five years of age was also recorded in the sub-region. While a proportion of this decline is attributable to the non-receipt of first quarter communicable disease reports from Guyana, significantly reduced notifications were observed in six CMCs [Figure 3b]. Fifty two percent of the ARI case reports during the first quarter of 1999, had originated from Guyana. Febrile Rash Illness During the first quarter of the current year, 89 patients were referred to CAREC with febrile rash illness through the Measles Elimination Surveillance System [MESS]. The ages of these patients ranged from five months to sixty years. None of these cases were laboratory confirmed either as measles or rubella. Although one suspected case of congenital rubella syndrome was notified from Jamaica, the IgM serologic assay was negative. Eleven cases of rubella were, however, notified to the Epidemiology Division through the national communicable disease reports received from the Cayman Islands. Five of these cases were confirmed through laboratory diagnosis, while six were confirmed on the basis of epidemiologic linkage. Gastroenteritis Notifications of cases of gastroenteritis among children less than five years of age were 25 percent higher during this quarter than during the corresponding period of 1999 [Table1]. Roughly 89 percent of the current notifications were reported from Jamaica, where an outbreak had been occurring. Similarly, of 5,485 cases of gastroenteritis notified from the entire sub-region among persons aged five years and over, 73 percent were recorded in Jamaica. During this quarter, case reports among persons, aged five and over, were also higher in Belize, the British Virgin Islands and Cayman Islands as compared with their 1999 data for the same period.
Outbreak Corner
Dengue fever: Suriname In February 2000, a joint team, consisting of staff from the Bureau of Public Health in Suriname and CAREC’s Epidemiology Division, undertook an epidemiological investigation of an outbreak of dengue fever, which had began during September 1999. The investigation confirmed that the outbreak had begun in the city of Paramaribo and in the District of Para [east of the city], from where it spread westward during the succeeding months to Commewijne, Wanica, Saramacca, Coronie and Nickerie [Figure 4]. No cases of dengue fever were reported either from the Brokopondo or Sipaliwini, two districts in the Interior. Monthly dengue fever incidence as reported via their hospital surveillance system [which comprises four hospitals in Paramaribo alone] rose from 37 cases in September 1999 to 259 in December of that year. Between September 1999 and March 2000, however, 1058 cases of dengue fever were cumulatively notified to the Bureau of Public Health through this specific arm of their national surveillance system [Figure 5]. An analysis of attack rates by geographic area indicated that Paramaribo and Wanica were the worst affected districts as evidenced by rates of 216 cases per 100,000 population [Figure 6]. It was also noted that the number of suspected or queried cases of DHF/DSS referred on a monthly basis for laboratory diagnosis increased from 5 in September to 33 in December 1999. Between September and December 1999, 90 or 33.0 percent of 274 patients, who were referred to the national Central Laboratory for diagnostic confirmation of dengue fever, were found to be positive. A review of the emergency room attendance records at the Nickerie hospital on Suriname’s western coast indicated that the proportion of emergency room attendees with signs and symptoms compatible with a diagnosis of suspected dengue fever had increased over the period from November 1999 through February 2000 [Figure 7]. A review of the hospital admission records revealed that the admission rates for patients with dengue compatible diagnoses had increased from 8 per 1,000 admissions in September 1999 to 50 by December 1999. Hospital records for the year 2000 were incomplete at the time of the investigation. In January 2000, the Aedes aegypti mosquito house indices in the Nickerie district were over 80.0 percent. Additional confirmation of the occurrence of an extensive outbreak of dengue fever was gathered from the "telefonade" surveillance network, which is comprised of thirty sentinel stations located in the coastal areas of Suriname [Figure 8]. Dengue virus types 1 and 2 were confirmed in Suriname during the outbreak. A significant part of this outbreak investigation was devoted to identifying whether cases of yellow fever may have been occurring in Suriname, following the WHO notification of a confirmed case of yellow fever that was imported into the Netherlands from Suriname. Our investigations failed to uncover any evidence of yellow fever transmission in Suriname.
CAREC wishes to gratefully acknowledge the sterling contribution of Dr. W. Punwasi, the national epidemiologist of Suriname and her team in this outbreak investigation. Rotaviral Gastroenteritis: Jamaica Beginning in November 1999, an increase in the number of reported cases of gastroenteritis was noted among children under five years of age in Jamaica. While this trend continued into the first quarter of the current year, there was a shift in the age distribution with cases being observed among older persons [Figure 9]. Outbreak activity peaked during epidemiologic week number 6 of 2000, in which 1,472 cases were notified. During that week, 9.9 percent of attendees at sentinel sites [54 in total] were diagnosed with gastroenteritis [Figure 10]. Increased notifications of gastroenteritis were recorded from all parishes across the country and no particular geographic clusters were identified. Rotavirus was independently confirmed as the aetiologic agent in this outbreak by the National Public Health Laboratory of the Ministry of Health; the Cornwall Regional Hospital Laboratory and the Virology Laboratory of the University of the West Indies. Ten deaths were recorded during this outbreak, all of which occurred among children less than five years of age. Completed epidemiologic investigations on four of these deaths indicated that they were due to dehydration.
In Jamaica, increases in reported gastroenteritis morbidity are often observed during the cooler months of the year and in anticipation of these usual seasonal trends, the national health authorities had published an advisory in their Weekly Surveillance Bulletin, as early as epidemiologic week number 42 of 1999. An intensive educational campaign was mounted, being directed to the public regarding the importance of oral rehydration and the need to seek medical attention in a timely manner, and to health care professionals on appropriate clinical management, specimen collection etc. The report of this epidemiologic investigation was provided to CAREC’s Epidemiology Division by Dr. Deanna Ashley, the Principal Medical Officer, and her team, Ministry of Health, Jamaica.
Editor’s Note The occurrence of this outbreak highlights the need for us to refocus on a number of important issues, a few of which are briefly discussed hereunder: Ministries of Health and their national health care systems must be in a constant state of preparedness, if they are to effectively manage large population outbreaks of gastroenteritis of sudden onset and to ensure that avoidable mortality does not occur. The same would also apply to cholera, even though, to-date, no cases have occurred in any of the Caribbean islands. The maternal and child health programmes of the 1980s and early 1990s achieved unparalleled success in reducing mortality due to gastroenteritis in the Caribbean and promoting the acceptance of oral rehydration therapy as a highly cost effective treatment regimen. However, a fundamental contributor to this success was the intense education of the public concerning the importance of oral rehydration in children with gastroenteritis and the need for seeking urgent medical attention for such ill children. However, there is clear indication of the need to revisit or reactivate some of those educational programmes as women of prime child-bearing age at this time, would represent a new cohort of mothers, who may not be as knowledgeable about their role in preventing dehydration of their babies.
An Outbreak of Meningococcal Infections Among Pilgrims Returning from the Hajj. An outbreak of meningococcal infections has occurred in Saudi Arabia and elsewhere among international travellers returning from the Hajj in Mecca. One hundred and ninety nine cases, including 55 fatalities, were reported from Saudi Arabia since the Hajj ended on March 18th, 2000. Neisseria meningitidis, serogroup A, was confirmed in 55 cases, while serogroup W-135 was identified in 30 cases [Eurosurveillance Weekly 2000; 4]. Cases were also recorded in Oman, where seven of twelve isolates were identified as serogroup W-135. Twenty-seven cases and 3 carriers were notified from England and Wales, with W-135 infections being diagnosed in all but one of the cases and two of the carriers. Similarly, one case of W-135 N. meningitidis was identified in Scotland. An outbreak, involving 16 cases of W-135 N. meningitidis infection, with a case fatality rate of 25%, was confirmed in France. All of the isolates belonged to the same subtype [2A:P1-2,5] [National Reference Centre for Neisseria, Institut Pasteur, Paris]. Four cases of W-135 [2A:P1-2,5] meningococcal infection were diagnosed in Holland, while, at least 3 cases linked to the Hajj were reported in the United States of America.
Following a large outbreak of group A meningococcal infections associated with the Hajj in 1987, the Saudi Arabian health authorities have required that visitors on pilgrimage must produce proof of vaccination against group A meningococcal infection. However, the vaccine formulation varies by country and the more commonly available bivalent A and C polysaccharide vaccines would not protect against W-135 serogroup infection. A quadrivalent polysaccharide vaccine containing serogroups A, C, Y and W-135, is the only meningococcal vaccine that is distributed in the United States of America [Morbidity and Mortality Weekly Report: 49(16);344-6 of April 28, 2000]. It is important to note, however, that polysaccharide vaccines do not prevent or eliminate carriage of meningococcal organisms and, hence, close contacts of returning pilgrims may be at risk of infection.
The Public Health Laboratory Information System Network [PHLIS] The enteric module of the Public Health Laboratory Information System was implemented at the Public Health Laboratory, Trinidad and Tobago in January 1999; at the Holberton Hospital Laboratory in Antigua in October 1999; and at the Victoria Hospital Laboratory, St. Lucia in February 2000. PHLIS: 1999 In 1999, laboratory results on 784 specimens were reported to CAREC through the PHLIS network. Twenty of these specimens originated from Antigua and Barbuda, while the remainder, 764, were from Trinidad and Tobago. Of the 20 stool specimens that were analysed for enteric pathogens from Antigua and Barbuda, only two were found to be positive, one for the parasite, Entamoeba histolytica and the other for Salmonella mississipi. Of the 764 specimens reported from Trinidad and Tobago, 554 or 72.5% were rectal swabs. The remaining specimens consisted of 200 stool samples; 8 blood samples; 1 gall bladder aspirate and one other sample for which no information on type was provided. Salmonella, Shigella and Campylobacter species were the only pathogens recovered by the Trinidad and Tobago Laboratory, though at very low yield rates. For example, Salmonellae were identified in 7 of the 756 samples tested; Shigellae in 18 of 751 samples and Campylobacter in 3 of 72 samples. PHLIS: First Quarter 2000 During the first quarter of 2000, laboratory results on 116 specimens were notified to CAREC through the PHLIS network [Table 3]. Salmonella organisms were cultured from 8 of the 116 screened specimens and Shigellae from 4 of 105 screened samples. Five of the Salmonellae were S. typhi, one of which was reported from Trinidad and Tobago, and two each from St. Lucia and Antigua/Barbuda, respectively. The 3 Salmonella group B organisms reported from Trinidad and Tobago came from one geographic area in Trinidad, while the two cases of Salmonella typhi in St. Lucia were documented in the Vieux Fort region. All of the Shigella positive specimens were from male patients in Trinidad and Tobago, with two being from children less than 5 years of age.
Dr. MJ Lewis, Dr. E. Boisson, Dr. S. Aldighieri and Team May, 2000
|
|
Caribbean Epidemiology Centre
|
