Tracking Mosquito Breeding Sites to Combat Zika in Honduras

Inspectors go door to door advising residents on how to prevent mosquitos from multiplying

Environmental health inspector Genzel Joel Ramos (right) tells Doña Isolina Vallecillo, a resident of the city of Danli, that the water in her wash basin, or “pila” in Spanish, contains the Aedes aegypti larvae. The inspectors apply a biological larvicide to her pila and explain how best to keep her water supply free of larvae and protect her family from Zika. / Brendan Bannon for USAID, courtesy of Photoshare

Gustavo Avila did not mince words. In speaking to a group of environmental health technicians about to be sent to four Honduran cities in search of mosquito breeding sites, he wanted to make sure they understood the gravity of their work.

“Even though you will not be performing surgery or attending to the sick, you will be out there saving the lives of your fellow citizens.

By localizing where the mosquitos lay their eggs, you will prevent people from being infected with Zika, chikungunya, and dengue. This is a major contribution to the public health of Honduras.” — Gustavo Avila

Gustavo Avila, who coordinates USAID’s efforts to combat Zika in Honduras, stands in front of an educational poster hanging in a health clinic in El Paraíso. The image shows the stages that the Aedes aegypti larvae go through in becoming an adult mosquito that could carry the Zika virus. The drawing shows the larvae developing in a “pila,” or household wash basin. / Brendan Bannon for USAID, courtesy of Photoshare

Avila, who coordinates USAID’s efforts to combat Zika in this Central American country, was referring to the eggs of Aedes aegypti, the mosquito that transmits Zika. Hondurans are no strangers to this mosquito, which also transmits chikungunya and dengue to humans.

In Honduras, the last outbreak of dengue, a flu-like illness that can sometimes develop into a lethal hemorrhagic fever, happened in 2010 with nearly 67,000 cases that resulted in 83 deaths. Although most people infected with Zika only have minor symptoms, others can experience long term consequences.

Pregnant women are especially at risk of Zika because they can pass the virus on to their fetuses, which can cause serious birth defects in newborns. This includes microcephaly, a condition in which the brain does not develop properly, thus resulting in smaller-than-normal head and impaired growth.

Zika is a relatively new threat in the region, as is chikungunya, which is why it is critical to go door to door to explain to Hondurans the risks of these diseases, how transmission happens, and what they can do to reduce or eliminate mosquito breeding sites.

Health inspectors Edwin Manfredo Aleman (left), Nelly Luatani Baldivia (center) and Genzel Joel Ramos go door to door in the city of Danli, Honduras to look for potential mosquito breeding sites and educate people about ways to prevent transmission of the Zika virus. / Brendan Bannon for USAID, courtesy of Photoshare

Edwin Manfredo Aleman is a mosquito control supervisor in the city of Danli, in the El Paraíso region of Honduras. He is one of 990 environmental health technicians who have been hired by USAID as part of a project implemented by Abt Associates to control Zika.

“At the beginning, people did not trust the health technicians coming into their homes, but slowly, and with the help of promotional campaigns through the local media, they understood our role.” — Edwin Manfredo Aleman

The health technicians that go door to door to inspect people’s homes usually work in pairs. Supervisors like Edwin oversee a total of 10 health technicians. Each technician visits 20 houses per day.

Applying larvicide to standing water kills existing mosquito larvae and is an essential step in containing the spread of the Zika virus. It is even more important that communities eliminate potential breeding sources so that the number of mosquitoes carrying the virus does not increase. Community health education is one highly effective way to address behaviors and practices that put entire families and communities at risk of contracting the virus. / Brendan Bannon for USAID, courtesy of Photoshare

At each home, the inspection teams look for open containers — such as plastic bottles, cement blocks, or even broken eggshells — that could fill with rainwater and become breeding sites for mosquitoes. They also check the open-air wash basins, pilas in Spanish, to test for mosquito larvae, and then add a biological larvicide manufactured in the United States, to the water in the basin.

“This larvicide is not toxic to humans and a small amount goes a long way,” said Richard Fisher, who manages the USAID project in Honduras. “It instantly kills the mosquito larvae in the pilas [wash basins in Spanish] but the challenges are cultural. Technicians must educate the landlords on how to avoid mosquito infestation.”

As often happens in public health, lasting solutions come from changing behaviors and practices. The larvicide is only the first step. Making sure the mosquitoes have nowhere to breed is even more important.

“Culturally, we are dealing with lack of education regarding hygiene practices,” said Blanca Martinez, epidemiologist and regional liaison officer for the USAID project.

“Poor neighborhoods do not get water regularly, sometimes only once or twice per month.

This means people keep water for household chores in buckets and open containers around the house, thus creating dangerous breeding grounds for the Aedes aegypti mosquito.” — Blanca Martinez

Blanca Martinez, epidemiologist and liaison officer for USAID’s project in the El Paraíso Health Region of Honduras. USAID’s Zika project is helping strengthen the El Paraiso’s health system response to the virus and mitigate its impact. / Brendan Bannon for USAID, courtesy of Photoshare.

One day when the inspection team visited the house of Doña Isolina Vallecillo, an elderly woman in the city of Danli, her pila tested positive for the Aedes aegypti larvae. After they applied the larvicide, the team talked to Doña Isolina and her 22-year-old niece Mara Loany about ways to keep the pila clean and avoid the creation potential of breeding sites.

In a nearby home, Ligia Carolina Arguijo’s pila was found free of larvae. Her house is well ventilated, and she regularly scrubs her wash basin, two practices that can keep houses free of mosquitos. However, her neighbor’s basin, located in the same shared inner courtyard, tested positive.

“Mosquitos travel up to 300-plus feet,” said USAID’s Avila. “Unless this becomes a community effort, people will still be at risk.”

Health inspector Genzel Joel Ramos empties a plastic container that could be a breeding site for mosquitos in a home he is visiting. Many residents have jobs far from their communities and leave their homes empty during the workweek, allowing water to accumulate around the residences, thus creating unchecked mosquito breeding sites. Inspectors must come back on weekends when the owners are more likely to be home. / Brendan Bannon for USAID, courtesy of Photoshare

The good news, according to regional health authorities, is that — as a direct result of the authorities’ outreach and control efforts — compared to last year, there is a 92 percent reduction in all mosquito-borne diseases, Zika included.

Indiana Argeñal, the regional health director for the El Paraíso region, said the USAID project is strengthening the country’s health system.

“We now have 69 technicians that go door to door, while before we only had five,” he said. “Thanks to them, we have a registry of data on mosquito infestation rates with details about each neighborhood and household. This enables us to make better decisions in our fight against Zika.”

About the Author

Beatrice M. Spadacini is a senior communications advisor for the Bureau of Global Health.