Intersectoral coordination, community empowerment and dengue prevention: six years of controlled interventions in Playa Municipality, Havana, Cuba

OBJECTIVE

To document the process, outcome and effectiveness of a community-based intervention for dengue control.

METHODS

The primary intervention, focused on strengthening intersectoral coordination, was initiated by researchers in January 2000 in a pilot area in Playa municipality, Havana. In August 2002 health authorities extended the intervention to neighbouring areas, one of which was selected for evaluation. In August 2003 a complementary strategy, focused on community empowerment, was initiated in half of the pilot area. In our control area, routine dengue activities continued throughout the study period. Longitudinal process assessment was carried out using document analysis, interviews and group discussions. Random population surveys in 1999, 2002 and 2005 assessed levels of participation and behavioural changes. Entomological surveillance data from 1999 to 2005 were used to determine effectiveness.

RESULTS

Mean scores for participation in the pilot area were 1.6, 3.4 and 4.4 at baseline, and 2 years after initiating intersectoral coordination and intersectoral coordination plus community empowerment interventions, respectively. While in the control area little behavioural change was observed over time, changes were considerable in the pilot and extension areas, with 80% of households involved in the community empowerment intervention showed adequate behavioural patterns. The pilot and extension areas attained comparable entomological effectiveness with significantly lower Breteau indices (BIs) than the control area. The pilot (sub-) area with the community empowerment intervention reached BIs below 0.1 that continued to be significantly lower than the one in the control area until the end of the study.

CONCLUSION

The study showed a trend in the levels and quality of participation, behavioural change and effectiveness of Aedes control from the routine activities only over an intervention with intersectoral coordination to one that combined intersectoral coordination and community empowerment approach.

Community participation in Aedes aegypti control: a sociological perspective on five years of research in the health area ''26 de Julio'', Havana, Cuba

OBJECTIVE

Effective dengue prevention and Aedes aegypti control is a priority for the Cuban health authorities. To enhance effectiveness, strategies oriented towards a more active involvement of communities in control activities are being tested. This paper presents a sociological perspective on a pilot project conducted in the health area ''26 de Julio'' (La Havana) in 1999-2004.

METHODS

Instrumental case study based on an exhaustive content analysis of project documents and on observations of a sociologist.

RESULTS

The context and the pilot project are systematically described and an analysis of the evolution of the underlying concept of community participation is provided. The pilot experience was a dynamic process influenced by self-reflection of the research team, feedback from research partners and changes in the epidemiological context (provoked by two dengue outbreaks during the study period). Community participation evolved from being just one component in Aedes aegypti control directed by the health staff into a learning and empowering process for the people. This change in the concept of participation was reflected in different aspects of the pilot project such as the learning and evaluation processes.

CONCLUSION

Empirical evidence from 5 years of research in the particular context of Cuba showed that moves towards community-based Aedes aegypti control are feasible. However, in order to be successful, community-based dengue prevention should be a social learning process, implying a transfer of power and responsibilities to local people. Actions undertaken must be oriented towards creating local capabilities, strengthening existing structures and organizations and promoting group work for learning participation from participation itself.

Race: a risk factor for dengue hemorrhagic fever

Cuban DHF/DSS outbreaks have provided evidence of a reduced risk of people of Negroid race for DHF/DSS compared to those of Caucasoid race. These observations from Cuban dengue outbreaks have significant epidemiological interest, as the differences in susceptibility to DHF/DSS among racial groups in Cuba coincide with that reported in African and Black Caribbean populations. In this article, we review the literature on race as a risk factor for DHF/DSS and discuss recent results from ongoing studies. Taking into consideration the origins of contemporary Cuban inhabitants, we propose that the Cuban, Caribbean Black and African populations share a common gene pool that could explain, at least partially, the low incidence of dengue hemorrhagic fever in Cuba and Caribbean and African countries. The central role played by immunological mechanisms in the pathogenesis of DHF/DSS has led us to consider that the polymorphic genes associated with the immune response must be carefully considered among those human genes regulating dengue disease severity that might be distributed unequally in Blacks and Whites.

[Emerging viral diseases]

In the last few years an increasing rise of new infectious diseases or of other diseases considered to be under control has been observed. The so called emerging and reemerging diseases are those new infections that have come up in a population or those existing diseases which incidence and geographic extension are on a rapid increase. Factors such as social and economic situations, medical assistance, food production, changes in human behaviours, environmental changes, health systems deterioration, and adaptation and changes of microorganisms are related with the emergence or reemergence of a number of entities. This paper sets forth an analysis of the emergence and reemergence of viral diseases and of those factors that have had an impact on this situation.

Comparison of rapid centrifugation assay with conventional tissue culture method for isolation of dengue 2 virus in C6/36-HT cells

A rapid centrifugation assay was compared with conventional tube cell culture for dengue virus isolation in both sera and autopsy samples from dengue and dengue hemorrhagic fever/dengue shock syndrome fatal cases. The rapid centrifugation assay allowed isolation of virus from 16.6% more samples than the conventional method, and it shortened the time for dengue virus detection. Finally, it allowed the isolation of dengue 2 virus in 42.8% of tissue samples from five fatal cases. Our results suggest that the rapid centrifugation assay may be useful for detection of dengue virus in clinical specimens.

Do escape mutants explain rapid increases in dengue case-fatality rates within epidemics?

During the Cuban dengue epidemics of 1981 and 1997, significant monthly increases were observed in the proportion of total cases that presented as dengue haemorrhagic fever or dengue shock syndrome (DHF/DSS), and in case-fatality rates for both dengue fever and DHF/DSS. We believe that theses increases can be explained by the hypothesis that some of the population of antibodies against dengue 1 virus raised after natural primary infections react with "neutralisation" determinants found on dengue 2 viruses. These heterotypic antibodies do not prevent secondary dengue 2 infections, but serve to down-regulate the disease to mild illness or symptomless infections. A population of dengue 2 viruses that replicates in dengue-1-immune hosts escape heterotypic neutralisation. When inoculated into a new dengue-1-immune host, these viruses are free to interact with the more abundant infection-enhancing antibodies to produce severe disease.

Fatal dengue hemorrhagic fever in Cuba, 1997

OBJECTIVES

After more than 15 years without dengue activity, a dengue II epidemic was reported in Cuba in 1997. Three thousand and twelve serologically confirmed cases were reported, with 205 dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) cases and 12 fatalities. This report presents the clinical, serologic, and virologic findings in the 12 fatal DHF/DSS cases.

METHODS

Serum and necropsy samples were studied by viral isolation in C636 cell line and polymerase chain reaction. Serum samples were tested by IgM capture enzyme-linked immunoassay (ELISA) and ELISA inhibition method (EIM).

RESULTS

All 12 cases were classified as DHF/DSS according to the Pan American Health Organization Guidelines for Control and Prevention of Dengue and Dengue Hemorrhagic Fever in the Americas. All patients were older than 15 years. Women were more frequently affected. The symptoms and signs presented by these patients were similar to those previously described in DHF/DSS cases. Clinical deterioration occurred on average at day 3.75. Abdominal pain and persistent vomiting were the earliest and most frequent warning signs. Dengue infection was confirmed in all cases. IgM antibodies were detected in 11 of 12 cases, all of them with a secondary infection. Dengue II virus was detected by viral isolation in 12 samples and by polymerase chain reaction in 17. Virus or RNA was detected in various tissues, including kidney, heart, lung, and brain.

CONCLUSION

The clinical, pathologic, and laboratory features of 12 cases of fatal dengue hemorrhagic fever were reviewed. The results obtained demonstrate that adults with a primary dengue infection are at risk of developing the severe disease (DHF) if they are infected with a different serotype.

[Epidemiology of dengue and hemorrhagic dengue in Santiago, Cuba 1997]

A dengue epidemic that Cuba reported in 1997 registered more than 500,000 cases of dengue fever produced by viral serotype 1. In 1981, there was an epidemic of dengue hemorrhagic fever produced by serotype 2 of the virus. This time 344,203 clinical cases were reported, 10,312 of which were severe cases of hemorrhagic fever that led to 158 fatalities (101 of them among children). The reintroduction of dengue, and specifically of dengue viral serotype 2 (Jamaica genotype), was quickly detected in January 1997 through an active surveillance system with laboratory confirmation of cases in the municipality of Santiago de Cuba, in the province of the same name. The main epidemiological features of this outbreak are reported in this paper. A total of 3,012 cases were reported and serologically confirmed. These included 205 cases classified as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), 12 of which were case fatalities (all among adults). Secondary infection with dengue virus was one of the most important risk factors for DHF/DSS. Ninety-eight percent of the DHF/DSS cases and 92% of the fatal cases had contracted a secondary infection. It was the first time dengue hemorrhagic fever was documented as a secondary infection 16 to 20 years after initial infection. Belonging to the white racial group was another important risk factor for DHF/DSS, as had been observed during the 1981 epidemic. During the most recent epidemic it was demonstrated that the so called "fever alert" is not useful for early detection of an epidemic. Measures taken by the country's public health officials prevented spread of the epidemic to other municipalities plagued by Aedes aegypti.

[The physicochemical characterization of the strains isolated during the outbreak of epidemic neuropathy in Cuba. II]

The presence of 2 agents such as a Cox A9 strain and another mild cytopathogenic effect-producing strain, both isolated from patients presenting with epidemic neuropathy is reported in this paper. A mild cutopathogenic effect which was propagated in successive dilutions was developed in the dilution 10(-4) by means of the neutralization test of a Coxsackie A9 virus with its homologous hyperimmune serum. A gradient in saccharose was performed in a mild cytopathogenic effect-producing strain and a typical cytopathogenic effect of an Enterovirus developed from one of the fractions passed in tissular cultures in the presence phosphonoacetic acid (PAA). The possible pathogenic role of these viruses are discussed.

[Cuban epidemic neuropathy. IV. The antigenic relationship of the viral isolates to the structures of the central nervous system. A possible etiopathogenic mechanism?]

Results which allow to state the existence of antigenic relationships between viruses isolated from the cerebrospinal fluid of patients presenting with epidemic neuropathy and structures of the human central nervous system are reported. These evidences were obtained by 2 different and independent ways: 1) by the double diffusion method in agarose, immunoblot analysis, and immunohistochemical analysis it was confirmed that antibodies induced by isolated viruses react with antigens of the central and peripheral nervous system, 2) serum obtained by the immunization of a rabbit with human brain extract neutralizes the same viruses as those neutralized by hyperimmune sera obtained by isolations. The possible role of viruses as mediators of an autoimmune process in the pathogenesis of the disease is discussed.

[The physicochemical characterization of the agents isolated during the outbreak of epidemic neuropathy in Cuba. I]

This paper reports on the physical and chemical characteristics of agents isolated from serum samples of patients presenting with epidemic neuropathy. The behaviour of isolated enteroviruses was as described for such viruses. Mild cytopathogenic effects-producing agents behaved in a variable form regarding sensitivity to chloroform; on the other hand they were neither sensitive to phosphonoacetic acid (PAA) nor to guanidine hydrochloride (GHC1) and grew in cells previously treated with bromodeoxyuridine (BDUR). These results suggest the presence of agents resembling enteroviruses and enveloped viruses. Further studies for the characterization of such agents need to be performed.

[Cuban epidemic neuropathy. I. Viral isolation]

From the end of 1991 to June, 1993, an epidemic neuropathy affecting 50,963 persons occurred in Cuba. Two clinical forms of the disease were observed: the optic form (with or without peripheral manifestations, 52% of the cases) and the peripheral form (48%). The epidemiological studies revealed nutritional disorders, mainly a vitamin B complex deficiency due to economic difficulties faced by the country in the "special period". Smoking habit and alcohol consumption were identified as risk factors, particularly for the most severe forms of the disease. In the virological studies of the cerebrospinal fluid (CSF) a Coxsackie 9 virus was isolated in Vero cells in 4% of the cases, as well as another agent with mild cytopathogenic effect in 80% of the samples. Sixty seven percent of the CSF samples inoculated to lactating mice caused the disease or the death of the animals. The viral persistence was confirmed in the cerebrospinal fluid during al least 21 days in a group of patients, and for a year in another group.

[Direct sequencing of an amplified product from a serum sample]

It is reported the nucleotide and amino acidic sequence of a great variability region in the dengue 2 virus genome, starting from the RNA of the original virus with no passage in the isolation systems. It is compared with the first strain of dengue 2 isolated during the 1981 epidemic with 4 passages in lactating mouse. Results show that the nucleotide sequence of serum and of strain A15 are the same.

[Genetic relatedness of the dengue 3 virus isolated in the outbreak of dengue hemorrhagic fever in Nicaragua, 1994]

It is reported the isolation of 2 dengue strains, 3 in samples from Nicaraguan patients suffering from dengue with hemorrhagic manifestations, which showed the reintroduction of this serotype in the region after being 17 years out of circulation. It is also reported the genetic characterization of the isolated strain, which, according to its classification, belongs to the group of dengue 2 strains isolated in Southeast Asi and which have been associated to hemorrhagic dengue. These results suggest the origin of this strain.

[Dengue in Panama, 1993]

Up to 1993, Panama was the only country in Central America where the autochthonous transmission of dengue virus had been detected without experimenting an explosive epidemic despite being reinfected with the Aedes aegypti mosquito since 1985. The characteristics of this first outbreak reported on November 19, 1993, are described in this paper. It is shown that even when there is a Program for the Surveillance and Control of Dengue, which considers low levels of Aedes aegypti infection and a system for the early detection of the virus, the epidemics appear if the community does not take an active part as it happened in 1994, 1995, and 1996. The 14 cases reported were located in an area under the responsibility of the Health Center in San Isidro, Belisario Porras, Special District of San Miguelito, in Panama City (13 cases in 4 blocks of the sector of Santa Librada and 1 case in San Isidro Valley). 3 patients were under 15 and 8 over 36, the other 3 were between 15 and 24.9 were females. The dengue type 2 virus was isolated in 3 patients. The presence of IgM and IgG antibodies to dengue was demonstrated in 11 patients, whereas in 8 over 20 it was observed a secondary type answer. According to the clinical picture, the epidemic was classified as dengue fever. The seroepidemiological survey carried out in the sector of Santa Librada and its surroundings 5 months after the appearance of the symptoms in the first case showed a prevalence of antibodies to dengue of 5.7% (46/802), mainly among individuals over 44. These results confirmed that the outbreak was geographically limited.

[Mechanism of Enterovirus participation in epidemic neuropathy. Physiopathological hypothesis]

During the epidemic neuropathy occurred in Cuba from 1992 to 1993, viral isolations antigenically connected with Coxsackie viruses were obtained from the cerebrospinal fluid of patients. Virological, epidemiological, toxicologic, nutritional, immunological and histopathological investigations were made. Though the disease was related to toxic and nutritional factors, it has been impossible to identify the cause of the epidemic. Taking into consideration the results of the different investigations, we have formulated a comprehensive and multifactorial hypothesis to explain the physiopathological mechanism of the participation of the isolated viruses as mediators in a process of autoimmunity of the pathogeny of the disease.

[Detection of IgM against the dengue++ virus in whole blood absorbed on filter paper]

This paper presents a standardized procedure for the detection of IgM antibodies to dengue virus in blood samples taken from filter paper. The samples were obtained from 118 patients, of whom 91 had been clinically diagnosed with dengue and 27 with a viral infection unrelated to that disease. The first group of patients came from Costa Rica and Nicaragua and the second group from Cuba. All the samples were tested for IgM antibody against dengue virus by means of a capture enzyme immunoassay (EIA). Analysis of the results for patients from all three countries together yielded a sensitivity of 98.1% and a specificity of 98.5% for the test done on whole blood on filter paper stored at 4 degrees C; agreement between the results of that test and those of the EIA using serum samples was 96%. In a comparison of the results obtained with three samples from the same patient--whole blood on filter paper stored at room temperature, the same type of sample stored at 4 degrees C, and serum--the agreement was 86%. This study demonstrates the high diagnostic sensitivity and specificity achieved when whole blood absorbed on filter paper is processed in the manner described in detail in the article. The authors recommend the use of this method in the dengue surveillance programs in the Region.

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.

Viral isolation from cases of epidemic neuropathy in Cuba

OBJECTIVE

To investigate the possibility of a viral agent in the central nervous system of patients with epidemic neuropathy.

DESIGN

Virus isolation attempts, in cell cultures and suckling mice, from cerebrospinal fluid (CSF) of neuropathy patients and controls undergoing lumbar puncture for unrelated reasons. Serologic studies in patients, contacts, and controls.

SETTING

An epidemic of optic and peripheral neuropathy affected more than 50,000 people in Cuba in 1991 through 1993. Illness was associated with dietary limitations and increased physical demands accompanying the shortages of food and fuel experienced in Cuba since 1989. Most patients responded to parenteral vitamin therapy, and the epidemic began to subside when oral vitamin supplementation was begun for the entire Cuban population.

RESULTS

Coxsackievirus A9 (five isolates) and a similar, less cytopathic virus (100 isolates) were recovered from 105 (84%) of 125 CSF specimens from neuropathy patients. The strains with light cytopathic effect were antigenically related to Coxsackieviruses A9 and B4 by cross-neutralization and immunoblotting assays. Virus persisted in CSF of some patients for 1 to 12 months. Cerebrospinal fluid from patients and both types of virus from cell culture produced illness, including complete posterior flaccid paralysis, in newborn mice, and virus was reisolated from the mice. Mouse tissues and sural nerve biopsy specimens from patients were stained by immunoperoxidase and colloidal gold techniques using hyperimmune rabbit antisera against the virus with light cytopathic effect.

CONCLUSIONS

Coxsackievirus A9 or an antigenically related agent with a light cytopathic effect was present in CSF of 84% of 125 patients with epidemic neuropathy. The role of these agents, probably in combination with nutritional factors, in the pathophysiology of the disease requires further investigation.

[Dengue in Nicaragua, 1994: reintroduction of serotype 3 in the Americas]

The principal aim of this work was to report the reintroduction of dengue virus serotype 3 in the Americas after an absence of 17 years. In addition, it describes the most common symptoms associated with classical dengue and hemorrhagic dengue and presents data on the distribution of the epidemic in the various comprehensive local health care systems of Nicaragua. The study group consisted of 39 patients hospitalized in Managua and León for dengue with hemorrhagic manifestations and hemorrhagic dengue. Of these patients, 34 were classified as probable or confirmed cases of dengue. The most frequent symptoms were fever, headache, vomiting, and muscle and joint pains. The tourniquet test was positive and thrombocytopenia was confirmed in 56% and 44% of the patients, respectively. Epistaxis (67%) was the most common hemorrhagic sign. Of the 356 serum samples received through the dengue surveillance systems in October 1994, IgM antibodies were detected in 43%. The virus was isolated from 5 of 24 samples tested (serotype 3 from 3 and serotype 1 from 2). The reintroduction of serotype 3 of dengue into the Region was demonstrated, along with its ability to produce epidemics of hemorrhagic dengue. The countries are warned that if they do not quickly take the measures described in the guidelines for the prevention and control of dengue and dengue hemorrhagic fever, new epidemics may occur in the Americas, given the large number of persons susceptible to this serotype and the high density of the mosquito vector in most of the countries of the Region.

[The use of ELISA and indirect immunofluorescence technics for the rapid detection of eastern equine encephalomyelitis]

We present the results attained in the identification of Eastern equine encephalomyelitis virus isolations in Vero and XL-2 cell systems, using a double-antibody ELISA technique and the indirect immunofluorescence method. The results attained through these two techniques coincided by 100% with identification through neutralization. With the former, the virus was detected within 6-8 hours after inoculation. Better results were attained with XL-2 cells.

[The estimation of the economic damages caused as a consequence of the epidemic of hemorrhagic dengue in Cuba in 1981]

In order to warn the health authorities in our region about the economic damages that a hemorrhagic dengue epidemic may cause, it was decided to study and publish the estimated cost of the Cuban epidemic in 1981, during which 344,203 diseased were reported, 10312 severe cases and 158 deceased. Economic costs include hospitalization expenses, assistance in emergency units, social security, expenses in out-patient treatment, goods not produced and expenses in the anti-vector campaign. Probably, this epidemic which could be controlled in about 4 months, has been the one causing most economic damages to date.