Colorado State Programs & People

Fighting Disease with (Sometimes) Simple Weapons

Published Fall 2007

On a given day in Mérida, the capital and largest city of the state of Yucatán in Mexico, tourists and residents alike can visit magnificent cathedrals and Mayan ruins and enjoy the rich cultural ambiance of the city.

Founded in 1542 by a Spanish conquistador, Mérida, which is about 22 miles from the Gulf of Mexico, is ranked 13th among the most populous Mexican cities.

Mosquitoes carry disease

During a trip to Mérida in early 2007, Barry Beaty, professor of virology at CSU, continued ongoing work with colleagues at the Universidad Autónoma de Yucatán to study dengue fever and an especially severe disease manifestation called dengue hemorrhagic fever.

Beaty, a University Distinguished Professor and director of the Infectious Disease Supercluster, says that dengue hemorrhagic fever started appearing in Mérida in about 1995 and that the disease ranges throughout the tropical world.

"Dengue fever affects probably 50 million to 100 million people a year," Beaty says. "It can affect so many people in a community that it has major socio-economic impacts." He adds that there is no cure and no vaccine to treat the disease once a person has been infected.The disease can cause high fever, joint pain, and bleeding from the skin, nose, and gums.

"We’ve estimated that more than 70 percent of the people in Mérida and the Yucatán have had contact with the virus," says Dr. Jose Farfan from the Yucatán University.

Mosquitoes are right at home

The dengue virus is carried by the Aedes aegypti mosquito, which favors houses for its life cycle. "That mosquito is very well adapted to humans," Beaty says.

The research project in Mérida seeks to attack dengue in two ways. One is to work with medical clinics in the colonias, or neighborhoods, and monitor when and where infections occur; thus, early warnings can be given in case of epidemics. Another approach is a preemptive strike to keep mosquitoes from living and feeding in houses. This approach, called Casa Segura (safe house), uses insecticide-treated curtains, a simple but effective method that Beaty is anxious to see succeed.

"We’re trying for better dengue control by instituting Casa Segura – stopping the mosquito from biting people in houses by hanging insecticide-treated curtains. We think we can protect a typical house for several years for less than $5. The curtains are effective for up to five years, so it would be a very good solution to a serious threat. It’s an exciting idea to be able to use available technologies."

Researchers also are using current technology to develop systems to better track infectious diseases. "We’re putting together what we call a Dengue Information System," says Lars Eisen, assistant professor in CSU's Department of Microbiology, Immunology, and Pathology. "It's a computer-based system incorporating GIS and analytical software that will help map locations of the cases and ultimately calculate how often disease occurs within populations in certain parts of the city."

The key is to make this new tool simple, inexpensive, and easy to fit in with existing control efforts, says Saul Lozano-Fuentes, postdoctoral research associate at Colorado State.

This year, mapping showed a cluster of dengue cases in neighborhoods surrounding a large cemetery in Mérida. Local mosquito control personnel know that standing water in cemetery flower pots can become breeding grounds for Aedes aegypti mosquitoes. While honoring their dead, Mérida's residents unknowingly support a dangerous disease.

Tiny insect, planet-sized problem

Mérida is not the only place with deadly infectious diseases. Beaty notes that, once detection and prevention systems are integrated into Mérida's public health programs, health officials will want to use the approach elsewhere to control the disease.

Better yet, the methods used to fight Aedes aegypti mosquitoes also may work for other diseases. "It’s an intervention that potentially goes beyond just one disease," Beaty says.

The collaboration between CSU and the Yucatán University also is helping to create a new generation of researchers and scientists.

"These problems really do exist on a global scale, and if we're going to make a difference, it's critical to train and develop cadres and networks of scientists worldwide," says Tony Frank, CSU's senior vice president and provost. Moreover, the bottom line for CSU's researchers is to help people who need it the most.

"In some of the very poor areas," Beaty says, "people may be bitten 100, 200 times a night by mosquitoes. Just controlling that would be wonderful – but then to go to the next step and help them in their health and happiness is a very laudable goal."

By Paul Miller, originally published in Colorado State Magazine Fall 2007.