Transcriptional analysis of four family 4 P450s in a Puerto Rico strain of Aedes aegypti (Diptera: Culicidae) compared with an Orlando strain and their possible functional roles in permethrin resistance.

A field strain of Aedes aegypti (L.) was collected from Puerto Rico in October 2008. Based on LD50 values by topical application, the Puerto Rico strain was 73-fold resistant to permethrin compared with a susceptible Orlando strain. In the presence of piperonyl butoxide, the resistance of Puerto Rico strain of Ae. aegypti was reduced to 15-fold, suggesting that cytochrome P450-mediated detoxification is involved in the resistance of the Puerto Rico strain to permethrin. To determine the cytochrome P450s that might play a role in the resistance to permethrin, the transcriptional levels of 164 cytochrome P450 genes in the Puerto Rico strain were compared with that in the Orlando strain. Of the 164 cytochrome P450s, 33 were significantly (P < 0.05) up-regulated, including cytochrome P450s in families four, six, and nine. Multiple studies have investigated the functionality of family six and nine cytochrome P450s, therefore, we focused on the up-regulated family 4 cytochrome P450s. To determine whether up-regulation of the four cytochrome P450s had any functional role in permethrin resistance, transgenic Drosophila melanogaster Meigen lines overexpressing the four family 4 P450 genes were generated, and their ability to survive exposure to permethrin was evaluated. When exposed to 5 microg per vial permethrin, transgenic D. melanogaster expressing CYP4D24, CYP4H29, CYP4J15v1, and CYP4H33 had a survival rate of 60.0 +/- 6.7, 29.0 +/- 4.4, 64.4 +/- 9.7, and 11.0 +/- 4.4%, respectively. However, none of the control flies survived the permethrin exposure at the same concentration. Similarly, none of the transgenic D. melanogaster expressing CYP4J15v1 or CYP4H33 ?5 survived when they were exposed to permethrin at 10 microg per vial. However, transgenic D. melanogaster expressing CYP4D24 and CYP4H29 had a survival rate of 37.8 +/- 4.4 and 2.2 +/- 2.2%, respectively. Taken together, our results suggest that CYP4D24 might play an important role in cytochrome P450-mediated resistance to permethrin.

Changes in host-seeking behavior of Puerto Rican Aedes aegypti after colonization.

The effects of colonization on host-seeking behavior of mosquitoes was examined by comparing attraction responses of newly colonized Aedes aegypti (L.) from field-collected eggs in Puerto Rico to that of the Gainesville (Florida) strain, originally from Orlando (Florida) and in colony since 1952. Females from the Orlando and the F0 through F10 generations of the Puerto Rico strain were evaluated using attractant odors in a triple-cage dual-port olfactometer. Two attractant sources were used: odors from the hand of a volunteer and a standard blend of L-lactic acid, acetone, and dimethyl disulfide. Convergence of the percentage of attraction responses occurred around the F4-F6 generations of the Puerto Rico strain. Both the Orlando and Puerto Rico strains exhibited similar responses for tests with the remaining F7-F10 generations. A temporal effect on mosquito responses was observed for both strains regardless of the attractant blend used in tests. This study indicates that Ae. aegypti host-seeking behavior changes significantly over the first four to six generations after introduction into the laboratory, whereas the field-collected strain increases in attraction response until it stabilizes at a new level.

An outbreak of dengue fever in St. Croix (US Virgin Islands), 2005.

BACKGROUND: Periodic outbreaks of dengue fever occur in the United States Virgin Islands. In June 2005, an outbreak of dengue virus (DENV) serotype-2 with cases of dengue hemorrhagic fever (DHF) was detected in St. Croix, US Virgin Islands. The objective of this report is to describe this outbreak of DENV-2 and the findings of a case-control study examining risk factors for DHF. METHODOLOGY/PRINCIPAL FINDINGS: This is the largest dengue outbreak ever recorded in St. Croix, with 331 suspected dengue cases reported island-wide during 2005 (62.2 cases/10,000 population); 54% were hospitalized, 21% had at least one hemorrhagic manifestation, 28% had thrombocytopenia, 5% had DHF and 1 patient died. Eighty-nine laboratory-positive hospitalized patients were identified. Of these, there were 15 (17%) who met the WHO criteria for DHF (cases) and 74 (83%) who did not (controls). The only variable significantly associated with DHF on bivariate or multivariable analysis was age, with an adjusted odds ratio (95% confidence interval) of 1.033 (1.003,1.064). CONCLUSIONS/SIGNIFICANCE: During this outbreak of DENV-2, a high proportion of cases developed DHF and increasing age was significantly associated with DHF.

Community beliefs and practices about dengue in Puerto Rico.

OBJECTIVE: In spite of long-term endemicity and repeated government and private efforts, effective, sustained community participation for dengue prevention remains a challenge in Puerto Rico. This study explored differences found in interviews conducted in 2001 in attitudes toward dengue and its prevention by respondents' gender and whether they had a prior dengue infection. Findings may be used to develop messages to promote Aedes aegypti control practices. METHODS: From September to October 2003, 11 focus groups were conducted in San Juan, Puerto Rico. Fifty-nine persons (35 women, 24 men), >or= 18 years of age, who had been identified through the Puerto Rico dengue surveillance system participated in the focus groups. Analysis was based on grounded theory. RESULTS: Women considered dengue important because of its economic, emotional, and health impact, and they were concerned more often than men about insufficient garbage removal and water disposal. Participants with a previous dengue diagnosis were more concerned about risk of the disease, were more knowledgeable about dengue and its prevention, and recommended use of repellents more often than their counterparts without a previous dengue diagnosis. Barriers to sustained dengue prevention included misconceptions from outdated educational materials, "invisibility" of dengue compared with chronic diseases, and lack of acceptance of responsibility for dengue prevention. CONCLUSIONS: Suggested strategies to motivate residents' actions included working with government agencies to address structural problems that increase mosquito populations, improving access to information on garbage collection and water disposal through telephone hotlines, increasing publicity and information about dengue by mass media campaigns, and educating health professionals.

Community beliefs and practices about dengue in Puerto Rico / Creencias y prácticas comunitarias relacionadas con el dengue en Puerto Rico

OBJECTIVE: In spite of long-term endemicity and repeated government and private efforts, effective, sustained community participation for dengue prevention remains a challenge in Puerto Rico. This study explored differences found in interviews conducted in 2001 in attitudes toward dengue and its prevention by respondents' gender and whether they had a prior dengue infection. Findings may be used to develop messages to promote Aedes aegypti control practices. METHODS: From September to October 2003, 11 focus groups were conducted in San Juan, Puerto Rico. Fifty-nine persons (35 women, 24 men), > 18 years of age, who had been identified through the Puerto Rico dengue surveillance system participated in the focus groups. Analysis was based on grounded theory. RESULTS: Women considered dengue important because of its economic, emotional, and health impact, and they were concerned more often than men about insufficient garbage removal and water disposal. Participants with a previous dengue diagnosis were more concerned about risk of the disease, were more knowledgeable about dengue and its prevention, and recommended use of repellents more often than their counterparts without a previous dengue diagnosis. Barriers to sustained dengue prevention included misconceptions from outdated educational materials, " invisibility" of dengue compared with chronic diseases, and lack of acceptance of responsibility for dengue prevention. CONCLUSION: Suggested strategies to motivate residents' actions included working with government agencies to address structural problems that increase mosquito populations, improving access to information on garbage collection and water disposal through telephone hotlines, increasing publicity and information about dengue by mass media campaigns, and educating health professionals.

OBJETIVO: A pesar de la prolongada endemia y los reiterados esfuerzos gubernamentales y privados, la participación efectiva y sostenida de la comunidad en las tareas de prevención del dengue sigue siendo un reto en Puerto Rico. A partir de entrevistas realizadas en 2001 se analizaron las diferencias en las actitudes hacia el dengue y su prevención según el sexo de los encuestados y sus antecedentes de haber sufrido esta enfermedad. Estos resultados pueden servir para desarrollar mensajes dirigidos a promover prácticas de control de Aedes aegypti. MÉTODOS: Entre septiembre y octubre de 2003 sesionaron 11 grupos focales en San Juan, Puerto Rico. Participaron 59 personas (35 mujeres y 24 hombres) de 18 años o más, identificados a través del sistema de vigilancia de dengue de Puerto Rico. El análisis se basó en la teoría fundamentada o inductiva. RESULTADOS: Las mujeres consideraban importante el dengue por su impacto económico, emocional y sanitario y más mujeres que hombres estaban preocupadas por la insuficiente recolección de basura y disposición de aguas residuales. Los participantes con diagnóstico previo de dengue estaban más preocupados por los riesgos de la enfermedad, conocían más sobre el dengue y su prevención y con mayor frecuencia aconsejaron el uso de repelentes que sus pares sin diagnóstico previo de dengue. Entre las barreras para la prevención sostenida del dengue estaban: conceptos erróneos por materiales educativos obsoletos, la " invisibilidad" del dengue en comparación con las enfermedades crónicas y la falta de aceptación de responsabilidad por la prevención del dengue. CONCLUSIONES: Las estrategias sugeridas para motivar la acción de los residentes comprenden: trabajar con las agencias gubernamentales para resolver los problemas estructurales que incrementan las poblaciones de mosquitos, mejorar el acceso a la información sobre la recolección de basura y la disposición de las aguas residuales mediante líneas telefónicas...

Mosquitoborne infections after Hurricane Jeanne, Haiti, 2004.

After Hurricane Jeanne in September 2004, surveillance for mosquitoborne diseases in Gonaïves, Haiti, identified 3 patients with malaria, 2 with acute dengue infections, and 2 with acute West Nile virus infections among 116 febrile patients. These are the first reported human West Nile virus infections on the island of Hispaniola.

Medical examiner samples: a source for dengue surveillance.

Post-mortem medical examiner samples may be useful for sentinel surveillance of disorders usually detected by antibody determinations on specimens from ill patients or from surveys. We found anti-dengue IgM positivity in 3% (23/780) and anti-dengue IgG positivity in 77% (597/777) of sera obtained at the Puerto Rico medical examiner (Institute of Forensic Sciences) in December 2000, April 2001, and October 2001. This approach may be a useful alternative for estimating the population prevalence of serologic markers for dengue and other infectious diseases.

Ecological factors influencing Aedes aegypti (Diptera: Culicidae) productivity in artificial containers in Salinas, Puerto Rico.

We investigated the effects of environmental factors and immature density on the productivity of Aedes aegypti (L.) and explored the hypothesis that immature populations were under nutritional stress. In total, 1,367 containers with water in 624 premises were studied in Salinas, southern Puerto Rico (May-July 2004). We counted 3,632 pupae, and most female pupae (70%) were in five of 18 types of containers. These containers were unattended and influenced by local yards' environmental conditions. Pupal productivity was significantly associated with the number of trees per premise, water volume, and lower water temperatures. Larval and pupal abundance were larger in containers with leaf litter or algae. Pupal productivity and biomass of emerging females varied in containers with litter of different tree species. We found a significant and positive association between numbers of larvae and pupae of Ae. aegypti and a negative relationship between larval density and mass of emerging females. From multivariate analyses, we interpreted that 1) food limitation or competition existed in a number of containers; and 2) to a lesser extent, there was lack of negative larval density effects in containers with a larger water volume and lower temperature, where emerging females were not under nutritional stress. Corroborating evidence for food limitation or intraspecific competition effects came from our observations that females emerging in the field had an average body mass comparable with those females produced in the laboratory with the lowest feeding regime. Ae. aegypti larvae in Salinas are most likely influenced by resource limitation or competition and by rainfall in unmanaged containers in the absence of aquatic predators. Source reduction and improved yard management targeting unattended containers would eliminate most Ae. aegypti productivity and removal or control of shaded, larger containers would eliminate the production of the largest emerging mosquito females in the study area.

Use of the pupal survey technique for measuring Aedes aegypti (Diptera: Culicidae) productivity in Puerto Rico.

The hypothesis tested was that most pupae of Aedes aegypti are produced in a few types of containers so that vector control efforts could concentrate on eliminating the most productive ones and thus prevent dengue outbreaks. Pupal surveys were conducted twice in 2004 in an urban area in southern Puerto Rico. A total 35,030 immature mosquitoes (III and IV instars, pupae) was counted in 1,367 containers found with water in 624 premises during the first survey. Only pupae were counted in the second survey in 829 premises, 257 of which had containers with water, and 124 contained Ae. aegypti pupae (15%, 22% in the first survey). We found fewer (583) containers with water than in the first survey, but 202 had pupae (35%; 18.5% in first survey). Containers yielded 3,189 Ae. aegypti pupae, which was slightly fewer than those found in the first survey (3,388 pupae). The hypothesis was supported by the data, showing that 7 of 18 types of containers contained 80% of all female pupae. The most productive containers generally were also common. We used several criteria (i.e., container use, two-step cluster analysis based on environmental variables of containers and premises) to classify the containers and premises and to evaluate pupal distribution at various spatial scales (container, premise, and residences versus public areas). Most pupae were in 4 of 10 types of container usage categories. The cluster technique showed that most pupae were in unattended, rain-filled containers in the yards, particularly in receptacles in the shade of trees that received rainfall through foliage and had lower water temperatures. Pupal counts were adjusted to a negative binomial distribution, confirming their highly aggregated dispersal pattern. Cluster analysis showed that 61.3% of female pupae were in 40 (6.4%) of 624 premises that had in common their larger yards, number of trees, and container water volume. Using number of Ae. aegypti larvae, Breteau Index, or the presence of immature forms as indicators of pupal productivity is not as efficient in identifying the most productive types of containers as direct pupal counts.

West Nile virus activity in Latin America and the Caribbean

OBJECTIVES: West Nile Virus (Flavivirus: Flaviviridae; WNV) has spread rapidly throughout the Caribbean Basin since its initial detection there in 2001. This report summarizes our current knowledge of WNV transmission in tropical America. METHODS: We reviewed the published literature and consulted with key public health officials to obtain unpublished data. RESULTS: West Nile virus infections first appeared in human residents of the Cayman Islands and the Florida Keys in 2001, and in appparently healthy Jamaican birds sampled early in 2002. Serologic evidence of WNV infection in 2002 was detected in horses, chickens and resident free-ranging birds in Guadeloupe, the Dominican Republic, and eastern Mexico. In 2003, WNV spread in Mexico and northern Central America, and serologic evidence was detected in the Bahamas, Puerto Rico and Cuba. In 2004, the first serologic evidence of WNV activity in South American ecosystems surfaced in September-October in Colombia and Trinidad, where domestic animals circulated WNV-neutralizing antibodies. CONCLUSIONS: The sparse reports of equine, human and avain disease in Latin America and the Caribbean is puzzling. Isolates are needed to evaluate viral attenuation or other possible explanations for reduced disease burden in tropical ecosystems (AU)

West Nile virus activity in Latin America and the Caribbean / La actividad del virus del Nilo occidental en América Latina y el Caribe

OBJECTIVES. West Nile virus (Flavivirus: Flaviviridae; WNV) has spread rapidly throughout the Caribbean Basin since its initial detection there in 2001. This report summarizes our current knowledge of WNV transmission in tropical America. METHODS. We reviewed the published literature and consulted with key public health officials to obtain unpublished data. RESULTS. West Nile virus infections first appeared in human residents of the Cayman Islands and the Florida Keys in 2001, and in apparently healthy Jamaican birds sampled early in 2002. Serologic evidence of WNV infection in 2002 was detected in horses, chickens and resident free-ranging birds in Guadeloupe, the Dominican Republic, and eastern Mexico. In 2003, WNV spread in Mexico and northern Central America, and serologic evidence was detected in the Bahamas, Puerto Rico and Cuba. In 2004, the first serologic evidence of WNV activity in South American ecosystems surfaced in September-October in Colombia and Trinidad, where domestic animals circulated WNV-neutralizing antibodies. CONCLUSIONS. The sparse reports of equine, human and avian disease in Latin America and the Caribbean is puzzling. Isolates are needed to evaluate viral attenuation or other possible explanations for reduced disease burden in tropical ecosystems.

OBJETIVOS: El virus del Nilo occidental (VNO, familia Flaviviridae, género Flavivirus) se ha propagado rápidamente por toda la cuenca del Caribe desde que se detectó por primera vez en 2001. En este informe se resumen nuestros conocimientos actuales acerca de la transmisión del VNO en zonas tropicales del continente americano. MÉTODOS: Revisamos todo lo que se ha publicado sobre el tema y consultamos a autoridades de salud clave para obtener datos inéditos. RESULTADOS: Las infecciones por el virus del Nilo occidental aparecieron por primera vez en seres humanos residentes de las Islas Caimán y de los Cayos de la Florida en 2001, y en pájaros de aspecto sano de los cuales se obtuvieron muestras a principios de 2002. En 2002 se encontraron pruebas serológicas de infección por el VNO en caballos, pollos y aves de corral no estabuladas oriundas de Guadalupe, la República Dominicana y la parte oriental de México. En 2003, el VNO se diseminó dentro de México y por la parte norte de Centroamérica y se encontraron pruebas serológicas en las Bahamas, Puerto Rico y Cuba. En 2004, las primeras pruebas serológicas de actividad vírica en ecosistemas sudamericanos se detectaron en septiembre y octubre en Colombia y Trinidad, donde se observaron anticuerpos neutralizantes contra el VNO en animales domésticos. CONCLUSIONES: Estos informes esporádicos de enfermedad equina, humana y aviar en América Latina y el Caribe son desconcertantes. Es necesario aislar las cepas para determinar si la atenuación del virus u otro factor explica la carga de enfermedad reducida en ecosistemas tropicales.

Knowledge and attitudes in Puerto Rico concerning dengue prevention.

OBJECTIVE: Dengue has been endemic in Puerto Rico for three decades. Multiple educational and community-based efforts have been developed to inform the population about dengue prevention. We undertook this study to understand the community members' knowledge, attitudes, and practices related to dengue prevention and to elicit their ideas for future prevention campaigns. METHODS: A qualitative study based on grounded theory analysis was conducted between February and May of 2001. The study involved a total of 34 participants in four group interviews who had been identified through the Puerto Rico dengue surveillance system. RESULTS: In general, participants had correct knowledge about dengue prevention, but they did not associate the mosquitoes inside their houses with Aedes aegypti. Participants insisted that "neighbors" needed to control larval habitats, and the participants also asked the Government to fumigate. CONCLUSIONS: The patterns of knowledge and opinion that emerged in the discussions can be arranged along an axis going from high levels of correct knowledge to low levels of correct knowledge about dengue and dengue hemorrhagic fever and related practices. There were few participants at either extreme. Three themes explained these patterns: misconceptions about dengue (based on previously delivered information), the "invisibility" of dengue (as compared to other diseases), and responsibility (individual and Government). Four strategies for preventive behaviors were recommended: developing community groups to identify community priorities on prevention, developing volunteer groups to deliver prevention messages, making house visits to demonstrate specific control measures, and conducting a complementary media campaign to support these strategies.

[How to respond to a dengue epidemic: overview and experience in Puerto Rico]. / Cómo responder a una epidemia de dengue: visión global y experiencia en Puerto Rico.

Dengue, a viral disease transmitted by mosquitoes, is endemic and frequently epidemic in many tropical countries. Because low-incidence periods vary in length, it is difficult to know in advance when an epidemic will occur. Response efforts, despite being logical, have been counter-productive at times. Furthermore, experience has demonstrated that dengue epidemics last a long time, making it important that government control efforts be sustainable while they last. This article describes priority activities requiring attention in order to minimize the impact of dengue epidemics. Such activities, which in many cases can be adapted to combat other types of epidemics as well, are as follows: (1) establishment of an inter-sectoral action committee, (2) formalization of an emergency action plan, (3) epidemiologic surveillance, (4) diagnostic laboratory testing, (5) mosquito control, (6) protection of sources of employment and special populations, (7) patient care, (8) education of medical personnel, (9) research, and (10) transparency before the mass media. The best way to reduce the ravaging effects of dengue epidemics is to anticipate their emergence so that infection can be prevented and steps can be taken to protect the ill. Relying on improvisation to solve all the problems that arise in moments of crisis is inefficient and reckless.

Cómo responder a una epidemia de dengue: visión global y experiencia en Puerto Rico / How to respond to a dengue epidemic: overview and experience in Puerto Rico

Dengue, a viral disease transmitted by mosquitoes, is endemic and frequently epidemic in many tropical countries. Because low-incidence periods vary in length, it is difficult to know in advance when an epidemic will occur. Response efforts, despite being logical, have been counter-productive at times. Furthermore, experience has demonstrated that dengue epidemics last a long time, making it important that government control efforts be sustainable while they last. This article describes priority activities requiring attention in order to minimize the impact of dengue epidemics. Such activities, which in many cases can be adapted to combat other types of epidemics as well, are as follows: (1) establishment of an inter-sectoral action committee, (2) formalization of an emergency action plan, (3) epidemiologic surveillance, (4) diagnostic laboratory testing, (5) mosquito control,(6) protection of sources of employment and special populations, (7) patient care, (8) education of medical personnel, (9) research, and (10) transparency before the mass media. The best way to reduce the ravaging effects of dengue epidemics is to anticipate their emergence so that infection can be prevented and steps can be taken to protect the ill. Relying on improvisation to solve all the problems that arise in moments of crisis is inefficient and reckless

Knowledge and attitudes in Puerto Rico concerning dengue prevention / Conocimientos y actitudes en Puerto Rico en torno a la prevención del dengue

Objective. Dengue has been endemic in Puerto Rico for three decades. Multiple educational and community-based efforts have been developed to inform the population about dengue prevention. We undertook this study to understand the community members' knowledge, attitudes, and practices related to dengue prevention and to elicit their ideas for future prevention campaigns. Methods. A qualitative study based on grounded theory analysis was conducted between February and May of 2001. The study involved a total of 34 participants in four group interviews who had been identified through the Puerto Rico dengue surveillance system. Results. In general, participants had correct knowledge about dengue prevention, but they did not associate the mosquitoes inside their houses with Aedes aegypti. Participants insisted that "neighbors" needed to control larval habitats, and the participants also asked the Government to fumigate. Conclusions. The patterns of knowledge and opinion that emerged in the discussions can be arranged along an axis going from high levels of correct knowledge to low levels of correct knowledge about dengue and dengue hemorrhagic fever and related practices. There were fewparticipants at either extreme. Three themes explained these patterns: misconceptions about dengue (based on previously delivered information), the "invisibility" of dengue (as compared to other diseases), and responsibility (individual and Government). Four strategies for preventive behaviors were recommended: developing community groups to identify community priorities on prevention, developing volunteer groups to deliver prevention messages, making house visits to demonstrate specific control measures, and conducting a complementary media campaign to support these strategies

Objetivo. El dengue ha sido endémico en Puerto Rico durante tres decenios, y varias iniciativas educativas y comunitarias se han puesto en marcha con objeto de informar a la población sobre la prevención de la enfermedad. Realizamos la presente investigación con el fin de entender los conocimientos, actitudes y prácticas de la comunidad en torno a la prevención del dengue y de recoger sus ideas acerca de futuras campañas de prevención. Métodos. Entre febrero y mayo de 2001 se llevó a cabo un estudio cualitativo basado en el método inductivo conocido por "categorización mediante teoría generada" [grounded theory analysis]. El estudio se efectuó con 34 participantes de cuatro entrevistas en grupo, todos ellos identificados mediante el sistema de vigilancia del dengue de Puerto Rico. Resultados. En términos generales, los participantes tenían conocimientos adecuados acerca de la prevención del dengue, pero no asociaban los mosquitos que había dentro de las viviendas con Aedes aegypti. Repetían con insistencia que "el vecino" tenía que controlar los hábitat larvarios, y también le pidieron al Gobierno que fumigara. Conclusiones. Los conocimientos y opiniones que afloraron en las discusiones mostraron ciertos patrones. Colocados a lo largo de un eje, estos revelaron un espectro desde muchos hasta muy pocos conocimientos que fuesen acertados acerca del dengue, la fiebre hemorrágica del dengue y las prácticas que deben observarse en conexión con estas afecciones. Hubo pocos participantes en un extremo u otro del espectro. Tres temas explicaron los patrones observados: ideas equivocadas en torno al dengue (basadas en información impartida anteriormente), la "invisibilidad" del dengue (por comparación con otras enfermedades), y la responsabilidad (individual y del Gobierno). Se recomendaron cuatro estrategias encaminadas a fomentar conductas de tipo preventivo: crear grupos comunitarios que identificaran las prioridades de la comunidad en materia de prevención; formar grupos de voluntarios que impartieran mensajes con fines preventivos; hacer visitas domiciliarias para demostrar ciertas medidas de control, y llevar a cabo una campaña de publicidad complementaria orientada a reforzar estas estrategias

Dispersal of the dengue vector Aedes aegypti within and between rural communities.

Knowledge of mosquito dispersal is critical for vector-borne disease control and prevention strategies and for understanding population structure and pathogen dissemination. We determined Aedes aegypti flight range and dispersal patterns from 21 mark-release-recapture experiments conducted over 11 years (1991-2002) in Puerto Rico and Thailand. Dispersal was compared by release location, sex, age, season, and village. For all experiments, the majority of mosquitoes were collected from their release house or adjacent house. Inter-village movement was detected rarely, with a few mosquitoes moving a maximum of 512 meters from one Thai village to the next. Average dispersal distances were similar for males and females and females released indoors versus outdoors. The movement of Ae. aegypti was not influenced by season or age, but differed by village. Results demonstrate that adult Ae. aegypti disperse relatively short distances, suggesting that people rather than mosquitoes are the primary mode of dengue virus dissemination within and among communities.