NEW YORK – The Chagas virus is a potentially lethal disease that international health authorities virtually universally agree has been brought to the United States in the flood of “unaccompanied minors” this year.
The United Nations World Health Organization describes Chagas disease as a “potentially life-threatening illness caused by the protozoan parasite, Trypanosoma cruzi (T. cruzi).”
“It is found mainly in endemic areas of 21 Latin American countries,” WHO says, “where it is mostly vector-borne transmitted to humans by contact with faeces of triatomine bugs, known as ‘kissing bugs,’ among other names, depending on the geographical area.”
A 2007 report titled “Chagas Disease: A Latin American Nemesis,” prepared by the Institute for One World Health under a grant donated by the Bill and Melinda Gates Foundation, documented that Chagas disease “is an insidious, potentially fatal parasitic disease that is widespread in Latin America affection 10-14 million or more.”
The 2007 reports noted Chagas “is transmitted primarily by a few species of a blood-feeding triatomine insect known as Vinchuca, the ‘kissing’ or ‘assassin’ bug.”
The report further documented that in Latin America, more DALYs (Disability Adjusted Life Years) are lost to Chagas disease than to meningitis, sexually transmitted diseases, hepatitis B and C, and malaria, with only HIV, diarrheal diseases and tuberculosis higher.
The 2007 report argued that in Latin America, the estimate of between 10 to 14 million infected with Chagas disease is low, with 16 to 18 million infected often reported. About 30 percent of infected individuals are expected to have or develop cardiac, peripheral nervous system or digestive system complications within 10 to 30 years after infection, with some expected to suffer sudden cardiac death.
Symptoms and conditions
The Centers for Disease Control and Prevention’s website explains that Chagas disease has an acute and a chronic phase that, if untreated, lasts a lifetime.
The CDC describes the effect of the disease in graphic terms:
Acute Chagas disease occurs immediately after infection, may last up to a few weeks or months, and parasites may be found in the circulating blood. Infection may be mild or asymptomatic. There may be fever or swelling around the site of inoculation (where the parasite entered into the skin or mucous membrane). Rarely, acute infection may result in severe inflammation of the heart muscle or the brain and lining around the brain.
Following the acute phase, most infected people enter into a prolonged asymptomatic form of disease (called “chronic indeterminate”) during which few or no parasites are found in the blood. During this time, most people are unaware of their infection. Many people may remain asymptomatic for life and never develop Chagas-related symptoms. However, an estimated 20-30% of infected people will develop debilitating and sometimes life-threatening medical problems over the course of their lives.
The CDC includes the following conditions among the complications of chronic Chagas disease:
- heart rhythm abnormalities that can cause sudden death;
- a dilated heart that doesn’t pump blood well;
- and a dilated esophagus or colon, leading to difficulties with eating or passing stool.
Now a threat in U.S.
Dr. Elizabeth Lee Vliet, a physician who has worked on medical projects in Central and South America since 2009, warned in an article titled “Deadly Diseases Crossing Border with Illegal Immigrants,” published June 25, that illegal immigrants from Latin America are bringing diseases the U.S. had controlled or virtually eradicated, including TB, dengue fever, hepatitis, malaria, measles and Chagas disease.
She warned, “A public health crisis, the likes of which I have not seen in my lifetime, is looming.”
She pointed out that most American physicians don’t think to check for Chagas disease, because it’s so uncommon in the U.S.
An article in the Scientific American published June 4, 2012, noted that Chagas is endemic in wetter, poorer areas of the world, closer to the equator. It breeds in impoverished areas where housing quality is poorer, garbage pickup intermittent and the water impure.
The article noted, “Since undocumented immigrants are difficult to track, officials have a hard time measuring and treating infected individuals, especially for diseases like Chagas that can remain dormant for years.”
An article published Feb. 16 in the American Journal of Tropical Medicine and Hygiene, authored by a team of physicians led by Susan P. Montgomery of the Division of Parasitic Diseases and Malaria at the CDC, “Neglected Parasitic Infections in the United States: Chagas Disease,” documented the incidence of Chagas disease in the U.S. has increased as a result of increased immigration from Latin America.
Montgomery and her colleagues concluded, “Based on immigration estimates for the United States and prevalence estimates in Latin America, more than 300,000 persons with Chagas disease are living in this country; many of these persons do not know that they are infected.”
Risks of transmission of the disease in the U.S. include infected mothers passing it to their infants and a person receiving a transfusion of blood donated by an infected person.
Montgomery and her colleagues also documented that the parasite T. cruzi has been found in many parts of the southern U.S.
“There are at least 11 species of triatomine bugs capable of transmitting T. cruzi in the United States, and in some areas more than 50% of triatomine bugs were found to be infected with the parasite. These bugs are found predominantly in areas where wildlife are common, unlike the peridomiciliary habitat of the triatomine species in Central and South America,” Montgomery wrote.
“Numerous animals can be infected and serve as a reservoir including wood rats, possums, raccoons, armadillos, and skunks.23 Domestic dogs may also become infected and manifest clinical cardiac disease; however, their role as reservoirs in the United States is not defined.”
No FDA-approved medication
A group of medical researchers at Baylor College of Medicine in Houston, in an article published Aug. 29 in the medical journal Epidemiology & Infection, found one in every 6,500 blood donors tested positive for exposure to the parasite that causes Chagas disease – a figure 50 times higher than the CDC’s estimated infection rate of one in 300,000 nationally.
They presented their findings Nov. 4 at the American Society of Tropical Medicine and Hygiene annual meeting in New Orleans.
“We were astonished to not only find such a high rate of individuals testing positive for Chagas in their blood, but also high rates of heart disease that appear to be Chagas-related,” said Baylor epidemiologist Melissa Nolan Garcia, one of the researchers who presented findings from a series of studies. “We’ve been working with physicians around the state to increase awareness and diagnosis of this important emerging infectious disease.”
Garcia noted that among those infected in the U.S., a high percentage is believed to have contracted the disease within the U.S. border.
“We think of Chagas disease as a silent killer,” Garcia told the New Orleans medical conference. “People don’t normally feel sick, so they don’t seek medical care, but it ultimately ends up causing heart disease in about 30 percent of those who are infected.”
“We’re the first to actively follow up with positive blood donors to assess their cardiac outcomes and to determine where southeastern Texas donors may have been exposed to Chagas,” Garcia said.
“We are concerned that individuals who test positive are not seeking medical care or being evaluated for treatment. And even if they do seek medical care, we heard from some patients that their primary care doctors assumed the positive test represented a ‘false positive’ due to low physician awareness of local transmission risk.”
A press release issued by the American Society of Tropical Medicine and Hygiene, or ASTMH, noted Garcia shared the findings from separate pilot studies conducted by the Baylor team, which followed 17 Houston-area residents who were infected.
The medical researchers found that 41 percent of them had signs of heart disease caused by the infection, including swollen, weakened heart muscle and irregular heart rhythms caused by the parasite burrowing into heart tissue. Most of these individuals lived in rural areas or spent a significant amount of time outside. One of the individuals was an avid hunter and outdoorsman. At least six of them had insignificant travel outside the United States, and they didn’t have mothers from foreign countries, indicating they likely had become infected in Texas.
Also presenting at the New Orleans conference was Dr. Jennifer Manne-Goehler, a clinical fellow at Harvard Medical School and Beth Israel Deaconess Medical Center. She collected data from the CDC and the American Association of Blood Banks and compared the almost 2,000 people who tested positive through the blood banking system to the mere 422 doses of medications administered by the CDC from 2007 to 2013.
“This highlights an enormous treatment gap,” Manne-Goehler told the New Orleans meeting. “In some of the areas of the country we know there are a lot of positive blood donors, yet people still don’t get care. We don’t know what happens to them because there is no follow-up.”
In the U.S., most physicians are unfamiliar with the disease, and some who have heard of it mistakenly dismiss it as an unserious health concern, even in parts of the country where many people may be living with Chagas symptoms, she commented.
Further complicating the situation in the U.S., the ASTMH press release noted, the U.S. Food and Drug Administration has not approved the currently available medicines used to treat Chagas disease.
Physicians seeking treatment for their patients are referred to the CDC, which makes two drugs – nifurtimox and benznidazole – available. Both carry the risk of side effects, including nausea, weight loss and nerve damage.