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Combatting the Kissing Bug

Mario Grijalva combats a disease—carried by a nocturnal insect—that affects millions worldwide
Frank Stevenson | Nov 22, 2013

 

Tonight, untold numbers of people throughout South and Central America will be bitten in their beds by a blood-sucking, nocturnal insect. It carries a parasite that causes a life-threatening disease for which there is no effective cure.

Within hours, many victims will begin to see ominous signs of the attack of the infamous triatomine, or "kissing bug." Some will find an eye swollen shut; others experience severe swelling wherever the bite occurred. Fever, fatigue, and nausea commonly follow.

Usually, after a few weeks, symptoms disappear completely, never to return in many cases. Unfortunately, for many the microscopic worm-like parasite sits biding its time inside its new host, waiting as long as two decades or more before causing health problems. Left untreated, victims later may experience sudden heart failure or damaged digestive tracts.

It's estimated that between 8 and 11 million people in Mexico, South America, and Central America are infected with this parasite, which causes a disease named Chagas after the doctor who first described it, according to the Centers for Disease Control and Prevention (CDC). Although the disease claims 21,000 lives per year, experts believe that the true number of deaths is underreported. Individuals are either never diagnosed with Chagas or die from the long-term side effects.

The World Health Organization lists Chagas as one of 17 so-called "neglected tropical diseases," or NTDs, a collection of common global maladies that don't draw the attention—or the research funding—that the world's most lethal epidemics do, such as HIV/AIDS, malaria, and tuberculosis. Of all the NTDs that plague the Americas, Chagas disease now ranks among the worst. 

But more health officials and researchers are beginning to take notice of this "silent killer," says Mario Grijalva, a Chagas disease expert who is director of Ohio University's Tropical Disease Institute.

"The high burden of Chagas disease in countries where the disease is endemic has been known for several decades. However, high rates of migration and globalization have increased the awareness about Chagas disease in non-endemic countries, including countries in Europe and to some extent in the United States," says Grijalva, an Ohio University professor of biomedical sciences in the Heritage College of Osteopathic Medicine.

 Grijalva and Ocana
Mario Grijalva, right, in the lab with postdoctoral fellow Sofia Ocaña-Mayorga. Photo credit: John Sattler, Heritage College of Osteopathic Medicine.

Since 2007, Grijalva has been involved with an effort led by the World Health Organization to examine how Chagas can be controlled globally. He's also been tapped for the Chagas Disease Epidemiological Network, a European Union project that studies the molecular pathway underlying the disease's spread in 12 countries in Latin America and Europe. 

Grijalva has more than 20 years of experience working to understand and combat the disease in his native Ecuador to bring to the table. Since joining the faculty in 1999, he's helped put Ohio University on the map as a leading center for Chagas research in a country where just a few other universities, working in conjunction with the CDC, are tackling the disease.

Revealing the silent killer

Although Chagas disease had been rife in his native Ecuador for centuries, the illness remained so obscure and so little understood that Grijalva first heard about it as a molecular and cell biology graduate student at Ohio University. The disease was first identified in 1909 by Dr. Carlos Chagas, a physician searching for the source of a mysterious, debilitating illness affecting patients in a small town in Northern Brazil.  He later would be nominated for a Nobel Prize for discovering that a common, sharp-nosed insect with a tick-like habit of feeding off the blood of mammals, including humans, also carried in its gut a free-swimming protozoan that caused the disease.

It wasn't until the late 1960s that "Chagas disease" was widely recognized as a major public health problem not just in Brazil but also throughout South and Central America. Experts say that the disease eventually kills up to 40 percent of its hosts. Intensive research led to coordinated control measures (heavily weighted toward using pesticides to exterminate the pest in houses) that eventually dropped infestation rates dramatically.

Control and prevention methods are important, as the search for an effective vaccine or drug to fight the disease continues. The two drugs typically used to treat Chagas, benznidazole and nifurtimox, are effective only during the early phases of infection, particularly in children under 12.  Because both drugs are heavily toxic, causing severe skin rashes, vomiting, and other side effects, neither is FDA-approved. In the United States, the CDC grants permission to use the drugs on a case-by-case basis.

"This is a major issue," says Grijalva. "Essentially, we don't have anything in (our medical arsenal) that's very effective against this disease. Right now, we have only two drugs used for treatment.  Both are not very good and both are highly toxic."

The disease also is becoming a greater concern in the United States, due to the rise in immigration of individuals from Chagas-endemic regions of South and Central America. The CDC estimates that 300,000 people here carry the disease, often acquired in their native countries. Although the triatomine bug can be found in the United States, "only rare vectorborne cases of Chagas disease have been documented," the CDC notes. However, health officials are keeping watch for signs of Chagas disease in blood transfusions and organ donations, as well as transmission from mother to baby during pregnancy.

Success in Ecuador

While the spread of Chagas from Latin America to other parts of the globe is alarming, health officials can seek hope in one place where Ohio University's Tropical Disease Institute has made progress in understanding and combating the disease: Grijalva's home country of Ecuador.
   
"Our institute's primary mission is to reach underserved populations with state-of-the-art training and technology to help eliminate or minimize the effects of these diseases," Grijalva says. "When we started (in Ecuador) we had almost nothing to work with. We've come a long way since then but we still have a long way to go."
 chagas
An international team of researchers and medical students led by Mario Grijalva travels to Ecuador each summer to continue to survey communities about triatomine infestations of Chagas disease. Photo courtesy of Grijalva.

Thanks to funding from such sources as the National Institutes of Health, the World Health Organization, and the Pan American Health Organization, Grijalva turned a small operation based in Quito into a powerful, multi-faceted research and training program that has caught the attention of the Ecuadoran government. Based largely on Grijalva's studies, in 2003 Ecuador's Ministry of Health officially made Chagas research a national priority by establishing the National Chagas Disease Program.

Today, Grijalva wears two hats in an international effort that by every measure is gaining respect for both its work and its boldness in what is still a largely unheralded field of community health care. The Ohio University Tropical Disease Institute he heads also is the mother of the Quito-based Center for Infectious Disease Research, which he also directs. That operation is a partnership with Grijalva's alma mater, Pontifical Catholic University, and is headquartered on its campus.
   
Thanks to this partnership, for years now Ohio University students have been afforded rare, real-world opportunities to learn about Chagas and other tropical diseases at places where such learning is best—inside communities constantly plagued by them. Beginning in 1997 with a small contingent of students and local volunteers, the Ohio University-Catholic University partnership now reaches out to 95 communities throughout Ecuador. Today, a team of about 30 specialists works on almost every aspect of Chagas disease, from the biology of kissing bugs and the protozoan parasite itself to diagnosing and controlling the disease in rural communities, Grijalva says. (Watch videos about the team's work here.)

With its largely rural population (about 40 percent), coupled with a national poverty rate that hovers around 30 percent annually, Ecuador represents an ideal proving ground for Chagas research.   Over the years, the disease has been found almost everywhere Grijalva's team has looked. And wherever it's gone to work, the team has made a lasting, live-saving difference, he feels.

When the team tallies its success stories, foremost among them is its impact in improving Ecuador's blood supply. Since the disease is easily transmitted by blood drawn from infected blood donors, establishing a fast, efficient, and reliable system of screening supplies for local and regional blood banks was recognized early on as a major weapon in the fight to arrest the spread of the disease. Until Grijalva brought Ohio University's resources in trained microbiologists and technology to bear on the problem, Ecuador had no effective system in place to screen blood. That's all changed, thanks to a successful blood bank initiative led by Grijalva's center in Quito. Almost anywhere in Ecuador today, patients needing transfusions have dramatically improved chances of receiving safe blood than they did a decade ago.  

During the past few years, one of the center's most ambitious efforts in the field has been centered in Ecuador's southernmost province known as Loja. This sprawling, mountainous region has been the focus of the center's "Healthy Living" project, an effort aimed at the long-term control of Chagas disease in this region. Despite having lived (and died) with the disease for generations, Loja's rural communities typify poor regions throughout South America that still are beset by widespread ignorance of what Chagas is, how it's transmitted, and how it can be controlled and prevented altogether. 

Relatively simple and inexpensive measures, such as keeping houses periodically fumigated with effective, bug-killing pesticides, was a novel idea in much of Loja until 2005, when the center launched a pilot disease control program in 58 of Loja's most Chagas-ridden communities. After a single year, the population of kissing bugs dropped dramatically in most communities where homes were treated. 

However, research conducted by Grijalva's group showed that bugs living in nearby sylvatic areas, mainly feeding on squirrels and rats, readily re-infested treated houses, with levels of disease transmission being restored as soon as two years later. Thanks to solid support from both government and non-government funding, the focus to find different alternatives to control Chagas in Loja continues. One of the priorities is helping some of Loja's most vulnerable communities amass funding to build better housing, which is generally seen as the first line of defense against the invasive, dangerous insects.
 chagas
Grijalva's research team conducts serological screenings for Chagas disease in rural areas of Ecuador. Photo courtesy of Grijalva.

The next generation of Chagas fighters

Grijalva's 20-year service at the front lines in the battle against Chagas disease in his native Ecuador is being recognized and rewarded in a profound way this year. Catholic University and Ohio University's 1804 Fund have awarded funding for six new Chagas projects, such as creating models of disease distribution, population genetic studies of the insects, epidemiological studies, and the design and construction of an "anti-Chagas house" this summer.

A coalition of funding sources impressed with the Quito center's record and its promise is making a major statement with construction of a ~100,000-square-foot research and training center. Now going up near the PCU main campus, the new facility is set to open sometime in 2014.

When fully operational, the new facility will be home to as many as 22 permanent Ph.D. researchers and dozens of support staff, along with some of the finest lab equipment and tropical disease research technology found anywhere, Grijalva says. He's confident that the facility's discoveries and spin-off technologies will benefit communities far beyond Ecuador, and may even lend a much-needed hand to Chagas-fighters in the United States.

"This will be a powerful magnet for researchers from throughout Latin America, not just for studying Chagas but also for a wide variety of other infectious diseases such as hepatitis, HIV/AIDS, tuberculosis, malaria, and dengue fever," he says. "It will enable us to greatly expand on what we've already been doing down there for years. We can't wait to get started."

This article appears in the Spring/Summer 2013 issue of Perspectives magazine, which covers Ohio University research, scholarship and creative activity.