It happened just like that. One day Barbara Saavedra’s modest adobe home, deep in southeastern Bolivia, turned white — and miraculously, for the first time ever, bug-free.
“The vinchuca were just gone,” said Ms. Saavedra, 39, a member of Bolivia’s indigenous Guarani people.
The vinchuca are Triatomine, or “kissing” bugs — large biting insects that live in the thatched roofs and mud walls of traditional homes like hers. They transmit a parasite that causes the incurable, and often fatal, Chagas disease.
The Chaco, the dry-forest region surrounding Ms. Saavedra’s village, is the epicenter of a worldwide Chagas epidemic affecting up to 10 million people, including one million in the United States. Ms. Saavedra’s family, and most of her neighbors, often slept outside to escape the bug’s nightly blood feedings.
Deliverance came in an unlikely form: On that August day, her home was slathered with a high-tech paint that kills disease-carrying pests like the kissing bug. Over the past decade, approximately 7,000 houses in the Chaco region have been covered with the paint, known as Inesfly. By most estimates, the vinchuca vanish within a week, and no houses have suffered repeat infestations, although some, like Ms. Saavedra’s, have been repainted as a precaution. The bug-killing paint has reduced infestation rates in her area from as high as 90 percent to nearly zero.
“It’s astounding,” said Dr. João Carlos Pinto Dias, a leading expert in Chagas disease at the Oswaldo Cruz Institute in Brazil. His studies found Inesfly effective for two years in real-life conditions. Standard insecticide application lasts only six months under the most ideal conditions and can dissipate within a week in harsh environments like the Chaco.
Developed by a small Spanish company called Inesba, the paint has not yet been fully evaluated by the World Health Organization; until it is, public health officials in many countries will not incorporate it into disease-control programs. But experimental efforts against a range of pests in South America, Mexico and Africa have produced promising results.
“The paint is changing the way we understand vector-transmitted disease and its prevention,” said Javier Lucientes Curdi, a parasitologist at the University of Zaragoza in Spain, who has been evaluating the paint’s ability to reduce transmission of dengue and sleeping sickness in Africa.
Inesfly comprises “microcapsules” of pesticides within a water-based paint. The active ingredients are released slowly over time, extending the paint’s effectiveness for years. The microcapsules also hold insect growth regulators, which kill insect eggs and their young. (Insecticides do not kill bugs in their early life stages.)
The microcapsules also act as the paint’s safety mechanism. Because the pesticides and insect growth regulators are released from the paint gradually, in tiny amounts, it is much less toxic than the fumigation on which many countries rely for pest control. There have been no reports or evidence of environmental or health complications related to Inesfly.