Reemergence of dengue in Cuba: a 1997 epidemic in Santiago de Cuba.

After 15 years of absence, dengue reemerged in the municipality of Santiago de Cuba because of increasing migration to the area by people from disease-endemic regions, a high level of vector infestation, and the breakdown of eradication measures. The 1997 epidemic was detected early through an active surveillance system. Of 2,946 laboratory-confirmed cases, 205 were dengue hemorrhagic fever, and 12 were fatal. No deaths were reported in persons under 16 years of age. Now the epidemic is fully controlled.     

Epidemiologic studies on Dengue in Santiago de Cuba, 1997

A small, isolated outbreak of dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) due to dengue virus type 2 (DEN-2) was documented in Santiago de Cuba on the island of Cuba beginning in January 1997. There were 205 DHF/DSS cases, all in persons older than age 15 years. All but three had evidence of a prior dengue infection, with the only known opportunity being the islandwide dengue virus type 1 (DEN-1) epidemic of 1977-1979. Virtually complete clinical and laboratory surveillance of overt disease was achieved. From December 1997 to January 1998, a random, age-stratified serum sample was obtained from 1,151 persons in 40 residential clusters in Santiago. Sera were tested for DEN-1 and DEN-2 neutralizing antibodies. The prevalence of DEN-2 antibodies in children age 15 years and under, born after the 1981 DEN-2 epidemic, was taken as the 1997 DEN-2 infection rate. This was adjusted slightly to accommodate observed cases, resulting in an estimated infection rate of 4.3%. Dengue fever and DHF/DSS attack rates were calculated from estimated total primary and secondary DEN-2 infections. Only 3% of 13,116 primary infections were overt. The DHF/DSS attack rate for adults of all ages was 420 per 10,000 secondary DEN-2 infections.     

Achieving sustainability of community-based dengue control in Santiago de Cuba

Achieving sustainability is one of the major current challenges in disease control programmes. In 2001-2002, a community-based dengue control intervention was developed in three health zones of Santiago de Cuba. New structures (heterogeneous community working groups and provincial/municipal coordination groups inserted in the vertical programme) were formed and constituted a key element to achieve social mobilization. In three control zones, routine programme activities were intensified. We evaluated the sustainability of the intervention strategy over a period of 2 years after the withdrawal of external support. Data on maintenance of effects, level of institutionalization and continuity of activities through capacity building were collected via documental review, direct observation, questionnaires, key informant and group interviews and routine entomological surveys. The intervention effects, evaluated through larval indices and behavioural change indicators, were maintained during the 2 years of follow-up. In the intervention area, 87.5% of the water storage containers remained well covered in 2004 and 90.5% of the families continued to correctly use a larvicide, against 21.5% and 63.5%, respectively in the control area. The house indices further declined from 0.35% in 2002 to 0.17% in 2004 in the intervention area, while in the control area they increased from 0.52% to 2.25%. Institutionalization of the intervention, assessed in terms of degrees of intensiveness (passage, routine, niche saturation), was reaching saturation by the end of the study. Key elements of the intervention had lost their separate identity and became part of the control programme's regular activities. The host organization adapted its structures and procedures accordingly. Continuous capacity building in the community led to participatory planning, implementation and evaluation of the Aedes control activities. It is concluded that, in contrast to intensified routine control activities, a community-based intervention approach promises to be sustainable.     

Economic impact of dengue and dengue hemorrhagic fever in the State of Zulia, Venezuela, 1997-2003]

OBJECTIVES: To determine the direct and indirect costs of medical care provided to cases of dengue and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) between 1997 and 2003 in Zulia State, Venezuela. METHODS: The total number of patients with dengue and DHF/DSS was obtained from records belonging to the Regional Epidemiology Office of the state of Zulia and from reports of cases that were confirmed in the Virology Section of Dr. Americo Negrette's Clinical Research Institute, Zulia University, Maracaibo, Venezuela, between 1 January 1997 and 31 December 2003. Direct costs included the cost of emergency medical care for all cases and hospital costs for cases with DHF/DSS (cost per bed-day and laboratory expenses). The costs connected to absence from work among patients over 15 years of age and mothers who accompanied their children under 15 years of age comprised the indirect costs, which were adjusted for the proportion of men and women in the labor force. Calculations were based on the minimum yearly wage, and results were given in United States dollars, converted according to each year's average exchange rate. RESULTS: During the study period, 33,857 cases of dengue and DHF/DSS were seen. Of them, 30 251 (89.35%) were cases of dengue, and 3606 (10.65%) were cases of DHF/DSS. Six cases of DHF/DSS died (lethality rate: 0.2 per 100 cases of DHF/DSS). Direct costs were 474,251.70 US dollars; of these costs, 132,042.30 US dollars were spent on emergency medical care and 342,209.40 US dollars on the hospital costs of DHF/DSS cases. Indirect costs were 873,825.84 US dollars and comprised 64.8% of overall expenditures (1 ,48,077.54 US dollars) connected to this disease during the study years. CONCLUSIONS: This is the first study on the economic impact of dengue in the state of Zulia and in Venezuela. In spite of some limitations, results show that dengue is an important public health problem that causes great expense because of temporary absenteeism from work and that undermines regional and national economic development.     

Towards active community participation in dengue vector control: results from action research in Santiago de Cuba, Cuba

Community participation is advocated as essential for attaining effective dengue prevention, but knowledge of how to foster this is limited. In Santiago de Cuba, multiple small task forces were created at the neighbourhood level that included all stakeholders in the control of Aedes aegypti. The task forces assessed the perceived needs and elaborated action plans to promote specific behavioural change and to reduce environmental risks through social communication strategies and intersectoral local government activities. We monitored five dimensions of the participation process and assessed behavioural and environmental results and entomological outcomes. Participation was weak to good. At the household level, uncovered water storage containers decreased from 49.3% to 2.6% between 2000 and 2002, and removing larvicide from them dropped from 45.5% to 1%. There was a reduction of 75% in the absolute number of positive containers and a significant decrease from 1.23% to 0.35% in the house index. Local task forces, in which the interests of householders as well as vector control workers are directly represented, can lead to effective government-community partnerships that resolve problems of mutual concern.     

Quality of drinking water and diarrheal diseases in Cuba, 1996-1997]

A study was conducted in 1996 and 1997 in 31 Cuban cities having a population greater than 35,000, in order to determine if there was a relationship between drinking water quality and the frequency of acute diarrheal diseases (ADD). We used the level of disinfection (based on chlorine concentration) as well as the level of bacterial contamination (based on the presence of coliform bacteria) as water quality indicators, and the frequency of ADD was calculated on the basis of the number of visits (per 100,000 inhabitants) to individual family physicians and to physicians on call in hospitals and polyclinics that were prompted by ADD. Weekly determinations of chlorine concentrations and monthly measurements of bacterial contamination were performed by taking daily water samples at 2,045 key sites along the water distribution channels in the cities included in the study. In 1996 and 1997, the percentages of samples with good chlorination (residual chlorine > or = 0.3 mg/L) for the entire country were 72.4% and 74.8%, respectively, whereas the percentages of samples with little bacterial contamination (most probable number [MPN] of fecal coliform bacteria < or = 9.2/100 mL) were 87.0% and 76.5%, respectively. Logistic regression revealed, at the local level, an inverse correlation between each of these percentages and the number of medical consultations for ADD (per 100,000 inhabitants), although it was not statistically significant. These results allowed the authors to stratify the cities included in the study according to their different levels of risk for ADD: high risk (23 cities), moderate risk (8 cities), and low risk (0 cities).     

Stratification of a hyperendemic city in hemorrhagic dengue]

Any effort to control dengue hemorrhagic fever (DHF) faces a number of challenges. Among these are the great environmental heterogeneity of homes and neighborhoods in urban centers where the primary dengue vector, Aedes aegypti, breeds, as well as shortages of resources and of personnel trained in mosquito control. Adequate epidemiological surveillance could serve as a basis to begin to stratify urban communities and identify the areas in them where control efforts should be focused. In this study we stratified Maracay, Venezuela, a city with hyperendemic dengue hemorrhagic fever, using a geographic information system and analyzing the persistence, incidence, and prevalence of dengue, by means of clinical diagnoses reported from 1993 through 1998. Maracay has around one million inhabitants living in some 349 neighborhoods in the six communities that make up the greater Maracay metropolitan area. During that 1993-1998 period the Maracay area reported 10,576 cases of dengue, 2,593 cases of DHF, and 8 deaths. The incidence of DHF was related to the incidence of dengue, the number of inhabitants in an area, and population density. The spatial pattern of dengue incidence was stable over the years that were studied, and significant, positive relationships were found between pairs of years and the incidence of dengue by neighborhood. The persistence of dengue was related directly to monthly incidence by neighborhood. These spatial patterns helped to divide the city into three strata: 68 neighborhoods without apparent dengue, 226 neighborhoods with low persistence and prevalence, and 55 neighborhoods with high persistence and prevalence. We recommend giving the highest priority for control efforts to these 55 neighborhoods, which make up just 35% of the Maracay urban area but had 70% of all the reported dengue cases.     

Dengue and dengue hemorrhagic fever: research priorities]

Dengue is one of the most important infectious diseases in tropical and subtropical countries. At present, the only strategy available to reduce the incidence of dengue is vector control. The World Health Organization and the Pan American Health Organization have called on all nations to take the needed steps to help diminish the burden of this disease and its medical and socioeconomic impact. It is hoped that it will be possible to reverse the increase in dengue and help control its spread through a coordinated, effective international response, along with epidemiological, clinical, and virological research that brings together the most advanced methods and techniques. This piece summarizes the most up-to-date information on dengue, analyzes current epidemiologic trends in the Region of the Americas, discusses the main global and Western Hemisphere initiatives to control the disease, and presents the main areas of research that should be developed in the immediate future.     

Epidemiology of dengue/dengue hemorrhagic fever in Malaysia--a retrospective epidemiological study 1973-1987. Part I: Dengue hemorrhagic fever (DHF).

Dengue hemorrhagic fever (DHF), though endemic in the sixties, emerged as a major public health problem in Malaysia from 1973 onwards. The incidence rate of DHF which was 10.1 per 100,000 in 1973 has fallen down to 1.9 per 100,000 in 1987 with a mean case fatality rate of 6.4 per 100 persons. The Chinese appear to be more prone to DHF with the highest mean morbidity rate of 5.5 per 100,000 and case fatality rate of 6.1%. The incidence of DHF is higher in the males with a higher case fatality rate in females. Male Chinese appear to be mainly affected. The overall age-specific incidence rate is highest in two age groups, viz. 5-9 years and 10-19 years of age with a mean morbidity rate of 4.9 cases per 100,000. The mean age-specific case fatality rate was highest in the 0-4 years age group. Dengue hemorrhagic fever is predominantly an urban disease in Malaysia with a mean incidence rate of 5.3 cases per 100,000 as opposed to 1.2 cases per 100,000 being reported from rural areas. The mean overall incidence of deaths in the urban area is 0.5 compared to 0.1 per 100,000 for rural areas. There is a marked seasonal correlation between DHF cases and rainfall, with a peak in August. While all four serotypes of dengue viruses are found in Malaysia, Den 2 appears to be isolated with greater frequency during all the epidemics.     

First outbreak of dengue hemorrhagic fever,Bangladesh

During the first countrywide outbreak of dengue hemorrhagic fever in Bangladesh, we conducted surveillance for dengue at a hospital in Dhaka. Of 176 patients, primarily adults, found positive for dengue, 60.2% had dengue fever, 39.2% dengue hemorrhagic fever, and 0.6% dengue shock syndrome. The Dengue virus 3 serotype was detected in eight patients.     

Santiago, a terror-stricken city]

The general purpose of this article is to determine how citizens' fear of lack of safety affects the use of public spaces. In an evaluation such as this, it is necessary to analyze two types of relationships pertaining to violence: the one between victimization and a perception of being unsafe, and the one that exists between social attitudes and the peaceful resolution of national conflicts. To this end, an analysis was performed of different variables--victimization, feeling unsafe, use of physical spaces, attitudes toward the established political and social institutions and toward the resolution of national conflicts--and of potential associations between these variables. The data for the study came from a survey of 1,200 persons between 18 and 70 years old who were residents of Santiago. Results show that Santiago's citizens live in fear and that their perception of a lack of safety has grown more intense, despite the fact that victimization rates remained relatively stable over the years preceding the survey. Fear is associated with an abandonment of both physical and sociopolitical public spaces, as well as with seeking refuge in private spaces and private life. There is a widespread attitude in favor of resolving conflicts through non-peaceful means, and such an attitude is more often associated with feeling unsafe, having negative attitudes toward democracy, and lacking hope in the nation's future. The results of this study support the notion that, in order to overcome their fear, people tend to adapt to reality by adopting a conformist attitude, taking on standard beliefs and behaviors, and overestimating the use of force as a way of resolving their differences.     

Dengue and dengue hemorrhagic fever, Brazil, 1981-2002

In the last 5 years, Brazil has accounted for approximately 70% of reported dengue fever cases in the Americas. We analyzed trends of dengue and dengue hemorrhagic fever (DHF) from the early 1980s to 2002 by using surveillance data from the Brazilian Ministry of Health. Two distinct epidemiologic patterns for dengue were observed: localized epidemics (1986-1993), and endemic and epidemic virus circulation countrywide (1994-2002). Currently, serotypes 1, 2, and 3 cocirculate in 22 of 27 states. Dengue and DHF affected mainly adults; however, an increase in occurrence of DHF among children has been recently detected in northern Brazil, which suggests a shift in the occurrence of severe disease to younger age groups. In 2002, hospitalizations increased, which points out the change in disease severity compared to that seen in the 1990s. We describe the epidemiology of dengue in Brazil, characterizing the changing patterns of it and DHF during the last 20 years.     

Dengue virus 3 genotype 1 associated with dengue fever and dengue hemorrhagic fever, Brazil

Dengue serotype 3 viruses were isolated from patients in Brazil from 2002 through 2004. On the basis of phylogenetic analyses, these isolates were assigned genotype 1. This genotype had never been reported in South America before. Its appearance indicates a major risk factor for dengue epidemics and severe disease.