Dengue Fever: Spreading the Message, Stopping the Disease

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Canada , Latin America , Mexico , Nicaragua , Peru , Southeast Asia , Topic: Intervention/Prevention , Topic: Systems Strengthening , United States

Dengue Fever Reemerges

Dengue fever is a mosquito-borne disease concentrated in the tropics. Massive insecticide-based efforts to control the dengue-transmitting mosquito, Aedes aegypti, almost completely eliminated dengue in Latin America, but not Southeast Asia, during the 1960s and 1970s. This success proved fleeting: Latin American governments soon ceased the resource-draining, military-style spraying programs.

Fed by rapid urbanization, the dengue fever epidemic emerged worse than ever in the 1980s. Dengue fever is now the most rapidly expanding insect-borne disease globally, with an estimated 50 to 100 million cases annually. Its most severe form, dengue hemorrhagic fever, leads to 25,000 – 50,000 deaths a year. There is no specific treatment for dengue, though supportive care in modern hospitals can prevent most of the mortality associated with the hemorrhagic form.

A major problem with mosquito control is that Ae. aegypti is highly adapted to urban conditions. It can lay its eggs in very small amounts of accumulated water, most notoriously in discarded plastic containers and tires. In addition, the intermittent or nonexistent public water supply in many poor neighborhoods leads residents to store water for the times when other sources are not available. These barrels and tanks become major Ae. aegypti breeding grounds if not kept covered. In many places, there are government-directed programs that use an antilarval pesticide to treat water tanks, but the pesticide raises toxicity concerns. It also frequently stops working due to the emergence of drug-resistant mosquitoes. Where Ae. aegypti remains sensitive to the pesticide, it shifts to new, safe areas to lay its eggs.

Dengue specialists in recent decades have recognized that sustainable control efforts must include community involvement. Such programs would bring the eyes and hands of the local residents to the job of eliminating breeding sites. The original community programs were still largely top-down, with community members merely following government instructions. “There is public education, messaging strategies, but nobody has attempted to engage the community. They are just telling the people what they need to do, and the result is not sustainable,” says Amy Morrison, who researches Ae. aegypti behavior and control in Peru.
One program that is trying to reverse this record of failure is the Camino Verde (Green Road) project in Nicaragua and Mexico.

Fellow Travelers on the “Green Road”

Camino Verde follows a bottom-up, community participation model. It is primarily the brainchild of Neil Andersson, executive director of CIET (Community Information and Epidemiological Technologies) and Eva Harris, Director of the Center for Global Public Health at the University of California Berkeley. The project is still in a trial phase.

CIET, founded in 1985, has a long history of conducting social mobilization projects around the world that seek to improve public health. In these projects, CIET partners with disadvantaged populations to help them identify and evaluate health concerns and the community resources available to solve them. CIET then works with community leaders and activists to develop public health strategies, based on open discussion of this evidence, which the locals themselves can put into action without relying on large grants or extensive government support.

In the process, CIET helps build local skills for research and planning beyond the issue at hand. CIET calls this process SEPA—“socializing evidence for participatory action.” CIET notably has applied this methodology to projects in Canada (indigenous youth suicide prevention), Mexico (diarrhea prevention and treatment), Pakistan (sexual abuse against women, health care delivery, diarrhea and childhood immunizations) and South Africa (sexual violence).

Mosquito poster child
A young Nicaraguan girl shows where to break the mosquito breeding cycle on the "green road" to dengue elimination. SEPA (socializing evidence for participatory action) doesn't tell communities what to do; it shows them how and why. Photo credit: Harold Suazo
Eva Harris conducts basic research on dengue biology and immunology at her Berkeley lab. She also directs a large Managua, Nicaragua, population cohort that tracks the dengue fever infection rate and, secondarily, influenza. Harris in addition is founder and president of the Sustainable Science Institute (SSI). SSI is a San Francisco, California-based NGO that trains scientists in resource-poor areas on ways to adapt high-tech diagnostic and epidemiologic methods to their limited means. Harris says about Camino Verde, “This project is a labor of love. It is very moving to see how you can use science to get into neighborhoods and change lives.”

CIET provides the staff and methodology for Camino Verde, and Harris and Andersson are principal investigators in Nicaragua and Mexico, respectively. SSI has a long-term agreement with the Nicaragua Ministry of Health. The director of the Ministry’s National Virology Laboratory also directs SSI’s National Virology Program and is a Camino Verde investigator.

Camino Verde’s major funder, the UBS Optimus Foundation, is an independent foundation established by the Swiss bank UBS. Its grant money comes from UBS clients, and the bank pays administrative expenses. UBS Optimus, which focuses on marginalized children, looks for ways to maximize the good it can do with its relatively small budget. Of Camino Verde, UBS Optimus program director Ann-Marie Sevcsik says, “Camino Verde seemed to offer the most bang for the buck. It is a favorite because of its mix of bottom-up and top-down. The experts work with communities to come up with their own solutions. This approach is not the cure but is cost effective and creates a sustainable response. Plus, the community organization model can be taken beyond dengue.”

Social Mobilization for Mosquito Control

Camino Verde’s forerunner was a UBS Optimus-funded pilot project that took place in Managua, Nicaragua from 2004 to 2007. The pilot project was an attempt to apply CIET’s SEPA model to dengue mosquito control. It has now grown into the full-fledged Camino Verde randomized controlled trial of community-based mosquito control.

The pilot established the basic SEPA method for dengue mosquito control, including the initial set of surveys. The surveys collect information about neighborhood demographics and social relationships and register residents’ views of community problems. Another part of the surveys ascertains neighborhood residents’ existing understanding of dengue and their mosquito-control practices. Children receive saliva-based tests for dengue antibodies (a sign of previous dengue infection). Lastly, likely mosquito breeding sites are searched out and examined.

Harris comments, “State programs around the world don’t explain anything. They just tell you to scrub your water barrels and spray them. We get people to examine what’s in the barrel and show how they can see the larvae.” Through its household-by-household surveys, Camino Verde attempts to convince neighborhoods of the magnitude of their dengue disease and mosquito infestation problems. The residents can see that interrupting the mosquito life cycle at an early stage is key to controlling the disease in their locale.

Camino Verde facilitators hold neighborhood focus groups to discuss the survey findings and develop anti-mosquito programs appropriate to the area. At the meetings, volunteers (“brigadistas”) take on the tasks of canvassing homes and implementing the measures.

Taking a step on the "green road" toward dengue elimination: Old tires filled with rainwater are a common breeding ground for mosquitoes. This community-led innovation takes those tires away from breeding mosquitoes and puts them to good use. Photo credit: Eva Harris
They share evidence from the community—samples of larvae and pupae, results from saliva tests—with the neighbors and they explain the life cycle of the mosquito. Using homemade tools, thye show houseyhold member4s how to find and do away with mosquito breeding sites. Water barrels are cleaned and covered, and trash removed. Sinks and other bodies of standing water are drained. Some of the old tires are filled with dirt and used for outdoor stairs, walls and plant containers. One Mexican community has discovered mosquito-eating fish, which it buys from local fishing folk for its water tanks.

The brigadistas regularly repeat their house visits to consult with residents about maintaining or improving their mosquito control. One problem that arose during the pilot project was that the metal covers on the water barrels became bent and let mosquitoes back in. Ae. aegypti actually prefers the partially covered barrels. In response, several community members began sowing and selling fabric covers with elastic rims. As with the mosquito-eating fish, this is a continuing neighborhood business.

The pilot project included 130 sites containing 30 houses each. Sites in ten of the neighborhoods received the CIET intervention while those in the other 20 neighborhoods served as reference sites. The intervention communities assessed the results yearly and made refinements in their social mobilization and anti-mosquito techniques.

Ramping Up

The pilot project’s results encouraged an expansion of the program. From 2004 through 2007, dengue infection in children declined by more than half in the pilot project areas; it was unchanged in the reference neighborhoods. By 2007, households in the intervention neighborhoods were 25 percent less likely than those in the reference sites to have Ae. aegypti breeding sites. In contrast, the intervention neighborhoods happened to be 30 percent more likely to have such infestations at the start of the intervention.

Three salient features of a successful program emerged from the pilot study. First is that sustaining the effort requires active local engagement. Neil Andersson says, “There are several aspects that are uniform in all the communities: There is a household component and a school component. In homes, the residents receive training and encouragement on their water tank interventions. Going to the schools and educating the students makes them real militants, invested in cleaning up around their homes.” Aside from household canvassing and classroom presentations, the Camino Verde message is kept in public consciousness through a series of local cultural and media events. These include street theater, animated cartoons, songs, and booths at community fairs.

Harris notes, too, that the Camino Verde programs have wider implications beyond eliminating mosquito larvae: “The brigadistas learn entomology and financial management. Women find empowerment and are more able to deal with domestic violence, which is a massive problem in Nicaragua.” (Camino Verde is now evaluating the exact extent of the reduction in domestic violence.) This sense of personal growth encourages the brigadistas to keep coming to the weekly meetings, where they discuss the social problems they come across during their house-to-house canvassing. Many brigadistas go on to activist or professional careers.

A third vital element is the need for rigorous statistical analysis. The pilot project took place in a few areas of a single city. According to Amy Morrison, who has served as UBS Optimus’s outside evaluator of Camino Verde, “There is a need to specifically track seasonal differences, natural variations and differences in the control [reference] neighborhoods. The community decision-making goes against the grain of the medical entomology community. Concrete data will convince entomologists to open up to the method.”

The current Camino Verde study therefore takes the form of a large comparative trial, in which the SEPA intervention is applied to certain neighborhoods and the resulting mosquito and disease rates compared with those in a like number of nearly identical control neighborhoods. Andersson says, “This is a pragmatic randomized controlled trial, so it takes place in a real life setting and will give strong data on costs. We want to provide a concrete comparison with pesticide costs as a basis for policy discussions.”

To demonstrate the method’s reproducibility, this three-year trial is taking place in two vastly different regions: Managua and Mexico’s Guerrero state (Acapulco and surrounding rural districts). The study area covers more than 100,000 people in 150 different neighborhoods. The trial has randomly assigned neighborhoods to the intervention or control groups, with each group balanced overall by location and mosquito and disease intensity. Initially, paid facilitators organize the Camino Verde working groups in the intervention neighborhoods; they gradually pull out as local volunteers take the lead in the process (this has already been accomplished in Nicaragua).

Brigadistas and facilitators from the intervention neighborhoods periodically visit other neighborhoods to evaluate those neighborhoods’ progress in mosquito control (this is known as peer-to-peer monitoring). When the trial winds down at the end of 2012, CIET staff and government workers not associated with Camino Verde will compare the intervention and control neighborhoods for mosquito infestations and childhood dengue infections. This will be a blind comparison; those doing the final analysis will not know which of the study neighborhoods underwent the SEPA process.

Two Different Political Cultures

Mexico and Nicaragua present different challenges for the Camino Verde model. Nicaragua has a recent history of revolution and social mobilization. The Nicaraguan government already sponsors community-based Citizens’ Power Councils that discuss social issues. Support from the Councils helps the Camino Verde committees take on a life of their own.

Guerrero State in Mexico has no parallel tradition, and the Camino Verde brigades are smaller and more formalized than in Nicaragua. Additional people volunteer, but less intensively. Much of this difference stems from the facilitators: CIET in Guerrero functions as a branch of the Autonomous University of Guerrero. It depends on the university to supply facilitators from among its students and graduates. They have advanced degrees in social and life sciences and most of them take a more standardized, academic approach to the SEPA model when setting up Camino Verde. In Nicaragua, the facilitators are experienced community leaders, frequently brigadistas from the pilot project, and their practice is based on personal experience to a greater extent.

Another difference is that the crime rate is very high in Acapulco. People are afraid to open their doors to strangers. Gaining their trust takes a sustained effort, which is made more complicated by the need for the facilitators to keep a low profile and avoid becoming targets of criminal attacks themselves. Managua, on the other hand, is more politically polarized. People opposed to the ruling Sandinista National Liberation Front will not cooperate with Camino Verde volunteers until they are assured that Camino Verde is independent of politics.

The Governments’ Role

Camino Verde nonetheless considers the Nicaraguan Ministry of Health a full partner in Camino Verde. The Ministry’s main anti-dengue strategy is mass insecticide spraying, but it also conducts its own educational efforts to induce people to remove mosquito breeding sites. When funding ran out for the pilot project in 2007, the Ministry used some of its pesticide funds to introduce Camino Verde methods in seven of the reference neighborhoods. The intervention neighborhoods in the pilot study mentored the Ministry-sponsored neighborhoods.

“We need to figure out an exit strategy with Ministry of Health,” says Eva Harris. “What happens when the funding runs out?” There should be some formal ongoing source of technical and financial support. She continues, “Brigadistas are getting elected to the local Citizens’ Power Councils, and this is necessary for the continuity of the program. But there are 1,000 barrios in Managua. How will Camino Verde spread to them?”

The government is also involved in Mexico’s Guerrero state, where it is more wedded to bureaucratic structures as well as pesticide spraying. Neil Andersson notes, “In Mexico, our approach is to work mostly with the high level officials and those on the ground – the vector control people. The Guerrero Secretary of Health is very much in favor of Camino Verde, and the director of vector control considers himself part of the project. So the government follows Camino Verde closely.” It helps that CIET is deeply implanted in Guerrero state, having functioned as part of the Autonomous University since 1985, where it forms the Centro de Investigación de Enfermedades Tropicales (Center for the Investigation of Tropical Diseases). The University’s current rector was one of the founders of and a past director of this CIET branch.

A major problem in both Guerrero and Managua is that many potential mosquito breeding sites are off-limits to the neighbors. Guerrero contains a large number of vacant lots waiting for their owners to return from working in the U.S. to build houses on them. The state recently passed a law allowing the Camino Verde volunteers to inspect these lots and clean up any stagnant water collections that they find. In Managua, the government has agreed to conduct “sanitary inspections” of businesses whose housekeeping practices are the most problematic from the point of view of mosquito control. It will allow Camino Verde volunteers to accompany the inspectors.

The community will always need a forceful government presence to manage water and waste management issues. Amy Morrison asks, “What happens if you can’t find the larval habitats because they are now hidden in places like sewers? It will be interesting to see Camino Verde negotiating with government to clean up sites that they can’t get to themselves.” The more successful Camino Verde becomes, the greater government cooperation it will need to go after the out-of-reach breeding sites that Ae. aegypti adopts.

Results so Far

Andersson argues that government experts’ participation in the Camino Verde final analysis will increase the chances of the governments’ long-term buy-in. He says, “In this way, they will believe the results that much more.”

One good sign already is that the first year of peer-to-peer monitoring in the Camino Verde trial intervention sites in Nicaragua found that the percentage of homes with mosquito breeding sites declined from 20 percent to 7 percent. It is evident that the Camino Verde organization can be sustainable, as many of the pilot project neighborhoods continue to have active programs, including selling the elasticized water barrel lids.

Amy Morrison commented that in her evaluation of the Nicaraguan and Mexican study sites, “Both models worked, though Mexico is further behind because it has been more difficult to gain residents’ trust. Still, they were making progress in Mexico, and I saw some of the same effects as in Nicaragua, including the personal growth aspect. Mexico is closer to Peru, so it makes me hopeful that the model can be applied in other locations. I have been trying to apply some of the features in our research since visiting the pilot project in 2006.” There is now discussion about bringing Camino Verde to Ecuador as well as expanding it to the rest of Nicaragua and Guerrero.

Integrating the Top and the Bottom

It is now more than 20 years since Duane Gubler of the U.S. Centers for Disease Control first argued for a community-based approach to dengue fever reduction, stating, “The only long-term, cost-effective approach to mosquito control is to convince the people who live in the homes where most transmission occurs to help the government control the mosquito vector.” Gubler called for an integration of “top-down” and “bottom-up” approaches.

As Gubler noted it is a long, involved process to get people to change their habits. Camino Verde promises to provide a “bottom-up” solution to this obstacle. Scaling it up will require government officials to change their habits, too, and that in itself may be an obstacle. Social mobilization can upend the established bureaucratic doling out of social services, forcing governments to provide more social services such as dependable water delivery and trash collection.

The public’s intervention need not be solely a source of new demands. Andersson says, “We are interested in whether the intervention neighborhoods show evidence of increases in social cohesion. We will measure things like decreased violence and greater uptake of vaccines. Also, will these communities now oppose pesticides?” Improved social cohesion can reinforce a broad range government programs, making politicians look more successful, but only if they are imaginative enough to support the end of business-as-usual.

(More information on CIET can be found at:

By David Gilden

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