Community-Based Dengue Control Study

In Nicaragua, as in most countries, top-down and pesticide-dependent approaches have failed to curb the spread of dengue. The Nicaraguan government strategy for control of the Ae. aegypti vector mosquito rests on periodic insertion of a packet of an organophosphate, temephos, in drinking water containers of all households, as well as spraying insecticides in urban areas. Although temephos has been used for decades, the multiple serotypes of dengue virus persist and continue to move northwards. Temephos is not licensed for human consumption in the USA, where it is produced (1, 2). Studies not sponsored by the industry have documented sub-lethal animal toxicity (3-5) and genotoxicity (6). Resistance of the mosquito to this pesticide is already well documented (7, 9-11) and, given the variable coverage and consistency of temephos use for dengue control, is a growing concern. However, in general, interventions focusing on education for dengue prevention have not produced the expected improvements in entomological indices or disease transmission. One exception was the pilot project we recently conducted in Nicaragua for 5 years. Our pilot project in Managua, which ended in 2008, included 10 intervention and 20 control clusters (neighborhoods) where we measured the impact of evidence-based community-led dengue control using entomological surveys and serological evidence of dengue virus infection in children 3-9 years old. We found significant improvements in entomological and serological indices, as well as protective attitudes and actions in the intervention clusters. This coincided with an increase in home inspections and household vector control activities by the residents themselves in intervention areas (12-15).

In partnership with CIET International and its Managua-based Office, SSI is part of a community-based study to dengue control: “Camino Verde: A randomized controlled cluster trial to reduce dengue risk in Nicaragua though evidence-based community mobilization,” which is a three year study aimed at developing a sustainable practice to motivate community members to participate in dengue control measures in a manner that is supported by local infrastructures. It uses an evidence-based approach that involves the community from the planning stages forward.

Sixty neighborhoods in Nicaragua are participating, with 30 as reference and 30 for the two interventions: 1) socializing evidence for participatory action in relation to dengue (Dengue-SePA) and 2) evidence-based planning (EBP).

The Dengue SePA will illustrate progress in behavioral, entomological and serological status, allowing people in intervention sites to see the impact of their efforts. In the third year, a measurement will estimate changes in the two main outcomes (serological status and presence of larvae/pupae). The second intervention arm (EBP) will allow for inference about the specific effects of the dengue information, rather than as a general effect of community mobilization based on any evidence.

References

1- Devine, G.J., and Furlong, M.J. (2007) Insecticide Use: Contexts and Ecological Consequences, Agriculture and Human Values, 24: 281-306.

2- WHO (2009) Temephos in Drinking Water: Use for Vector Control in Drinking Water Sources and Containers, Draft background document of WHO Guidelines for Drinking Water Quality (www.who.int/entity/water_sanitation_health/dwq/.../temephos.pdf)

3-USEPA (2008a) Temephos RED (Reregistration Eligibility Decision). Washington, DC, US Environmental Protection Agency (http://www.epa.gov/oppsrrd1/REDs/temephos_red.htm).

4- Anadu, D.I., Anaso, H.U., and Onyeko, O.N.D., (1996), Acute toxicity of the insect larvicide abate (temephos) on

the fish tilapia melanopleura and the dragonfly larvae neurocordelia virginiensis, Journal of Environmental Science and Health, Part B, 31: 1363-1375.

5- Sparling, D.W., Lowe, T.P., and Pinkney, A.E. (1997) Toxicity of Abate to Green Frog Tadpoles, Bulletin of Environmental Contamination and Toxicology, 58: 475-481.

6- Aiub CAF, Coelho ECA, Sodre E, Pinto LFR and Felzenszwalb I. (2002) Genotoxic evaluation of the organophosphorous pesticide temephos, Genetics and Molecular Research, 1: 159-166.

7- Braga, I.A., Lima, J.B.P., da Silva Soares, S., and Valle, D., (2004), Aedes aegypti Resistance to Temephos during 2001 in Several Municipalities in the States of Rio de Janeiro, Sergipe, and Alagoas, Brazil, Memorias do Instituto Oswaldo Cruz, 99: 199-203.

8- Chen, C.D., Nazni, W.A., Lee, H.L., and Sofian-Azirun, M. (2005) Susceptibility of Aedes aegypti and Aedes albopictus to temephos in four study sites in Kuala Lumpur City Center and Selangor State, Malaysia, Tropical Biomedicine, 22: 207-216.

9- Jirakanjanakit, B., Saengtharatip, S., Rongnoparut, P., Duchon, S., Bellec, C., and Yoksan, S. (2007) Trend of Temephos Resistance in Aedes aegypti Mosquitoes in Thailand during 2003-2005, Environmental Entomology, 36: 506-511.

10- Lima, J. B.P, da Cunha, M.P., da Silva Junior, R.C., Galardo, A.K.R., da Silva Soares, S., Braga, I.A., Ramos, R.P., and Valle, D. (2003) Resistance of Aedes aegypti to organophosphates in several municipalities in the state of Rio de Janeiro and Espõ´rito Santo, Brazil. American Journal of Tropical Medicine and Hygiene, 68: 329-333.

11- Rodriguez, M. M., Bisset, J., de Fernandez, D.M., Lauzan, L., and Soca, A., (2001), Detection of insecticide resistance in Aedes aegypti (Diptera: Culicidae) from Cuba and Venezuela. Journal of Medical Entomology, 38: 623-628.

12- Arostegui, J., Carcamo, C., Hammond, S.N., Coloma, J., Balmaseda, A., Andersson, N., Harris, E., and the CIET Dengue Group-Nicaragua. Evidence-based community-derived interventions for the control of the dengue virus vector Aedes aegypti in Managua Nicaragua. 54th Annual Meeting of the American Society of Tropical Medicine and Hygiene, Washington, DC, December 11-15, 2005.

13- Arostegui, J., Hammond, S.N., Carcamo, C., Suazo, H., Coloma, J., Balmaseda, A., Andersson, N., Harris, E., and the CIET Dengue Group-Nicaragua. Impact of evidence-based community-derived interventions for the control of the dengue virus vector Aedes aegypti in Managua, Nicaragua. 55th Annual Meeting of the American Society of Tropical Medicine and Hygiene, Atlanta, GA, November 12-16, 2006.

14- Arostegui, J., Suazo, H., Carcamo, C., Hernandez, C., Coloma, J., Balmaseda, A., Andersson, N., Harris, E., and the CIET Dengue Group-Nicaragua. Sustained impact of evidence-based community-derived communication strategies for the control of the dengue virus vector Aedes aegypti in Managua, Nicaragua. 56th Annual Meeting of the American Society of Tropical Medicine and Hygiene, Philadelphia, PA, November 4-8, 2007.

15-Arostegui, J., Suazo, H., Coloma, J., Carcamo, C., Hernandez, C., Balmaseda, A., Andersson, N., Harris, E., and the CIET Dengue Group-Nicaragua. Impact on serological, entomological, and behavioral indices of an evidence based community-derived communication program for the control of Aedes aegypti and dengue in Managua, Nicaragua. 57th Annual Meeting of the American Society of Tropical Medicine and Hygiene, New Orleans, LA, December 7-11, 2008.