A KAP study on dengue/dengue haemorrhagic fever (DF/DHF) was carried out in three areas in the Federal Territory. The three areas were selected based on their ethnic group composition and were Jinjang North (Chinese), Kampung Bahru (Malays) and Sentul (Indians). Houses were selected by a systematic sampling method and house-to-house interviews were carried out with a pre-tested, predesigned questionnaire. 546 (87.62%) of the households responded.
A nation-wide outbreak of 260 cases of DF/DHF with 1 death occurred in Singapore from Apr-Sept 1986. The outbreak originated from 3 separate foci of transmission at the western, south-eastern and north-eastern parts of the island and then spread to other dengue receptive urban and suburban areas. The morbidity rate was highest in young male Chinese adults between 15 and 24 years of age. The outbreak was rapidly brought under control through destruction of adult Aedes mosquitoes, surveys and source reduction of larval breeding habitats, health education and to a certain extent law enforcement. The Aedes population was high in the main foci of transmission although the overall house index was only 1.1. Other factors which could have precipitated the outbreak included waning herd immunity of the human population and continuous introduction of dengue virus into the country.
Field trials were conducted in two residential areas of Petaling Jaya Municipality to test the adulticidal and larvicidal effects of malathion 96% TG and Resigen on Aedes aegypti. Malathion is the currently used insecticide in Malaysia for the control of dengue. The Leco HD ULV machine was used throught the trials. For malathion the flow rate was 90 ml/minute at a vehicle speed of 8kph and for Resigen the flow rate was 200 ml/minute at the same vechicle speed. Malathion was more effective giving higher mortality rates when compared with Resigen. The mortality rate of adult Ae. aegypti outdoor was higher than in the living room and kitchen. Both insecticides did not show promising larvicidal effects.
Dengue Fever (DF) and Dengue Haemorrhagic Fever (DHF) have been the most common urban diseases in Southeast Asia since the 1950s. More recently, the diseases have spread to Central and South America and are now considered as worldwide diseases. Both Aedes aegypti and Aedes albopictus are involved in the transmission of DF/DHF in Southeast Asian region. The paper discusses the present status and future prospects of Aedes control with reference to the Malaysian experience. Vector control approaches which include source reduction and environmental management, larviciding with the use of chemicals (synthetic insecticides and insect growth regulators and microbial insecticide), and adulticiding which include personal protection measures (household insecticide products and repellents) for long-term control and space spray (both thermal fogging and ultra low volume sprays) as short-term epidemic measures are discussed. The potential incorporation of IGRs and Bacillus thuringiensis-14 (Bti) as larvicides in addition to insecticides (temephos) is discussed. The advantages of using water-based spray over the oil-based (diesel) spray and the use of spray formulation which provide both larvicidal and adulticidal effects that would consequently have greater impact on the overall vector and disease control in DF/DHF are highlighted.
About two-thirds of the world's population live in areas infested with dengue vectors, mainly Aedes aegypti. All four dengue viruses are circulating, sometimes simultaneously, in most of these areas. It is estimated that up to 80 million persons become infected annually although marked underreporting results in the notification of much smaller figures. Currently dengue is endemic in all continents except Europe and epidemic dengue haemorrhagic fever (DHF) occurs in Asia, the Americas and some Pacific islands. The incidence of DHF is much greater in the Asian countries than in other regions. In Asian countries the disease continues to affect children predominantly although a marked increase in the number of DHF cases in people over 15 years old has been observed in the Philippines and Malaysia during recent years. In the 1990's DHF has continued to show a higher incidence in South-East Asia, particularly in Viet Nam and Thailand which together account for more than two-thirds of the DHF cases reported in Asia. However, an increase in the number of reported cases has been noted in the Philippines, Lao People's Democratic Republic, Cambodia, Myanmar, Malaysia, India, Singapore and Sri Lanka during the period 1991-1995 as compared to the preceding 5-year period. In the Americas, the emergence of epidemic DHF occurred in 1981 almost 30 years after its appearance in Asia, and its incidence is showing a marked upward trend. In 1981 Cuba reported the first major outbreak of DHF in the Americas, during which a total of 344,203 cases of dengue were notified, including 10,312 severe cases and 158 deaths. The DHF Cuban epidemic was associated with a strain of dengue-2 virus and it occurred four years after dengue-1 had been introduced in the island causing epidemics of dengue fever. Prior to this event suspected cases of DHF or fatal dengue cases had been reported by five countries but only a few of them fulfilled the WHO criteria for diagnosis of DHF. The outbreak in Cuba is the most important event in the history of dengue in the Americas. Subsequently to it, in every year except 1983, confirmed or suspected cases of DHF have been reported in the Region. The second major outbreak in the Americas occurred in Venezuela in 1989 and since then this country has suffered epidemics of DHF every year. Between 1981 and 1996 a total of 42,246 cases of DHF and 582 deaths were reported by 25 countries in the Americas, 53% of which originated from Venezuela and 24% from Cuba. Colombia, Nicaragua and Mexico have each reported over 1,000 cases during the period 1992-1996. About 74% of the Colombian cases and 97% of the Mexican cases were reported during 1995-1996. A main cause of the emergence of DHF in the Americas was the failure of the hemispheric campaign to eradicate Aedes aegypti. Following a successful period that resulted in the elimination of the mosquito from 18 countries by 1962, the programme began to decline and as a result there was a progressive dissemination of the vector so that by 1997 with the exception of Canada, Chile and Bermuda, all countries in the Americas are infested. Other factors contributing to the emergence/re-emergence of dengue/DHF include the rapid growth and urbanization of populations in Latin America and the Caribbean, and increased travel of persons which facilitates dissemination of dengue viruses. Presently, all four dengue serotypes are circulating in the Americas, thus increasing the risk for DHF in this region.
Matched MeSH terms: Severe Dengue/prevention & control
Cyfluthrin (Solfac ULO15) and malathion 96 TG were evaluated against sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti at high-rise flats in Malaysia by ULV spraying. The impact of both insecticides on field populations of Aedes spp. (Ae. aegypti and Ae. albopictus) larvae were monitored weekly using containers. Both cyfluthrin and malathion 96 TG showed adulticidal effects but cyfluthrin showed more significant larvicidal effect than malathion 96 TG (P < 0.05).
Dengue virus infection is now a global problem affecting tens of millions of people. The spread of the four dengue virus serotypes had led to increased incidence of dengue haemorrhagic fever (DHF) reported and with 2.5 billion people at risk, efforts towards the development of safe and effective vaccines against dengue must be accelerated. This chapter reviews some of the important lessons of pathogenesis which may be learnt from classical studies in the field and place these in the context of current knowledge about the molecular biology of the virus. The issues which have to be addressed in designing a safe vaccine against dengue are raised and the problems of designing subunit as well as whole virus vaccines are pointed out, particularly with regard to the phenomenon of antibody dependent enhancement and, more generally, the problem of immune potentiation of disease. More efforts must be made to understand the basis of pathogenesis in DHF and in finding out what nature has to teach about protection against and recovery from dengue virus infection.
Matched MeSH terms: Dengue/prevention & control*; Severe Dengue/prevention & control
Deltacide (S-bioallethrin 0.71% w/v, deltamethrin 0.5% w/v, piperonyl butoxide 8.9% w/v excipients to 100% w/v) and Solfac UL 015 (cyfluthrin 1.5% w/v) were evaluated against the sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti at 17 storey high-rise apartments in Malaysia using ULV applications. The impact of both insecticides on field populations of Ae. aegypti and Ae. albopictus larvae was monitored weekly using bottle containers. Both Deltacide and Solfac UL 015 showed adulticidal and larvicidal effects. This was the first field trial using Deltacide against dengue vectors in Malaysia and showed its potential for use in dengue vector control programs.
The purpose of this study was to identify the early indicators of hemorrhage in severe dengue infections in 114 patients; 24 patients had severe hemorrhage and 92 had no hemorrhage. The platelet counts were not predictive of bleeding. The duration of shock (OR, 2.11; 95% CI, 1.13 to 3.92; P =.019) and low-normal hematocrit at the time of shock (OR, 0.72; 95% CI, 0.55 to 0.95; P =.020) were risk factors of severe hemorrhage.
Matched MeSH terms: Severe Dengue/prevention & control*
Cynoff 25ULV (cypermethrin 25 g/l) and Solfac UL015 (cyfluthrin 1.5% w/v) were evaluated against the sentinel sugar-fed adults and 4th-instar larvae of Aedes aegypti in a housing estate endemic of dengue in Malaysia. The impact of both pyrethroids on field populations of Aedes albopictus and Aedes aegypti larvae was monitored weekly using bottle containers. Both Cynoff 25ULV and Solfac UL015 showed adulticidal effects and larvicidal effects. This field trial using Cynoff 25ULV against dengue vectors showed its potential for use in dengue vector control programs.
We compared 53 patients with Dengue shock syndrome (DSS) who received preventive transfusions with 53 who did not. Significant differences in the development of pulmonary edema and length of hospitalization (P
Matched MeSH terms: Severe Dengue/prevention & control*
A cross-sectional survey was conducted to assess the level of knowledge, attitude and practices concerning dengue and its vector Aedes mosquito among selected rural communities in the Kuala Kangsar district from 16-25th June, 2002. It was found that the knowledge of the community was good. Out of the 200 respondents, 82.0% cited that their main source of information on dengue was from television/radio. The respondents' attitude was found to be good and most of them were supportive of Aedes control measures. There is a significant association found between knowledge of dengue and attitude towards Aedes control (p = 0.047). It was also found that good knowledge does not necessarily lead to good practice. This is most likely due to certain practices like water storage for domestic use, which is deeply ingrained in the community. Mass media is an important means of conveying health messages to the public even among the rural population, thus research and development of educational strategies designed to improve behaviour and practice of effective control measures among the villagers are recommended.