New hope for a neglected disease
Mamma always said you can do anything you put your mind to. But that's both a blessing and a curse. Science has made some amazing strides in medicine, but where minds—and money—aren't applied, progress sputters.
Chagas is a parasitic disease spread by a bug. Somewhere between 8 and 20 million people—mostly in the Americas—are infected. No one knows for sure. Most of the victims are poor.
A little over 100 years after the parasite that causes Chagas was first discovered, this disease is still difficult to diagnose, treatment regimens are complicated and fraught with side-effects and 20,000 people die from Chagas each year. The best hopes are prevention campaigns, and a new generation of drugs that researchers hope will be easier to take.
In the blood
In urban areas, blood banking is also an issue, because Chagas can be passed through transfusions. Unfortunately, there's not a lot of attention on this. Even the United States only introduced blood-donor screening for the disease in 2007, and that's still a voluntary measure that not all blood centers practice, said Dr. Susan Montgomery, veterinary medical officer and epidemiologist with the Centers for Disease Control and Prevention. Since screening began, it's identified more than 1000 infections, mostly in new immigrants who picked up the parasite in their home countries. Only seven cases of US-acquired Chagas have been reported in scientific literature, Montgomery said, but she and other experts suspect there are more that have gone unnoticed.
Chagas is caused by a parasite, called Trypanosoma cruzi. Just as the malaria parasite hitches a ride on mosquitoes, T. cruzi also travels by blood-sucking pest—in this case triatomine bugs, also called "kissing bugs" because of their tendency to bite people on the face at night. Unlike mosquitoes, kissing bugs don't pass their parasites to humans via saliva. Instead, they further the indignity by relieving themselves on people they've just bitten. When the victim tries to swat the bug away, or even just rolls over in their sleep, they can smear bug waste&and T. cruzi parasites along with it—into their eyes, nose or mouth.
Some of these people will never know that they've been infected. Up to 70% of those who carry T. cruzi parasites never have any serious symptoms. Others won't know they're infected for years. They'll live with no sign of disease, sometimes passing the parasites on to their children in utero, until it's too late.
When you die of Chagas disease, you aren't killed directly by parasites. Instead, Chagas victims suffer years of chronic organ damage—usually to the heart, digestive or nervous systems.
"We don't know why some patients end up with severe damage and others don't," said Rick Tarleton, Ph.D., president of the Chagas Disease Foundation and professor of cellular biology at the University of Georgia. "My personal hypothesis is that the human immune system actually does a fantastic job of battling this parasite. But decades of killing parasites and their infected host cells produces tissue damage. Individual results depend on a lot of factors: Host genetics, the efficiency of the immune system, their living situation, their nutritional level, their level of stress, their gender, the parasite strain they picked up and how long they've been infected," he said.
There are drugs to treat Chagas disease, but they can only go after the parasites, not heal the tissue damage. And poverty plays a big role in both spreading the disease and complicating treatment. In rural areas of Central and South America, where Chagas is endemic, people live in thatch and adobe houses that are perfect nesting ground for kissing bugs. Inevitably, they get bit, but they also don't have much access to health care, so it's rare to be tested for the disease until symptoms appear.
"The available drugs are expensive. You have to take two pills a day for 60 days and there's a lot of serious side effects, nausea, skin disease problems. Treatment has to be monitored closely by a doctor. None of that's feasible for rural areas. And the side-effects also make it difficult to treat patients in the chronic phase, those most likely to be diagnosed, because of their organ damage," said Eric Stobbaerts, policy & advocacy coordinator for the not-for-profit product development partnership Drugs for Neglected Diseases Initiative. .
Right now, prevention is the most effective protection against Chagas. And, basically, that boils down to bug spray.
With most of the funding for Chagas focused on killing kissing bugs before they bite, the Drugs for Neglected Diseases Initiative has focused its work on making it easier to treat the infected. They're going about that two ways. First, they're trying to make it easier to treat children. Chagas can be passed from mother to baby, but none of the available drugs are produced in child-size doses, Stobbaerts said. That often leaves rural doctors trying to hand-cut adult pills into eight or 12 pieces. Within a year, the Drugs for Neglected Diseases Initiative hopes to release a real pediatric formulation.
The organization is also working on a new drug treatment that could be less of a pain to take. Called ravuconazole, it's related to a common family of anti-fungal drugs. In vitro tests, and trials in lab animals have shown that ravuconazole can kill T. cruzi parasites. The tests also suggest that it stays in the body longer than current Chagas drugs, meaning fewer pills could do the same job. It also seems likely to produce fewer side effects. Clinical trials in humans are set to begin later this year.
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Maggie:
THANKS A LOT. Thank you, thank you, very much.
I work with Chagas disease, and it we have a problem of lack of awareness. People do not know, or they do not care, and it is a huge problem that remains untouched, as the disease is silent, not spectacular. Even some doctors back in Venezuela think that the disease can be cured.
Chagas has been proposed as the source of Charles Darwin's chronic illness. He reported having been attacked by the kissing bug (also known as the assassin bug) in Argentina, while on the Voyage of the Beagle.
But this is not the most likely cause of his illness, more recent and convincing suggestions include the ulcer-causing bacterium Helicobacter pylori or Cyclic Vomiting Syndrome, an illness associated with mitochondrial DNA abnormalities.
http://en.wikipedia.org/wiki/Charles_Darwin's_illness
Kissing bugs are Assassin bugs which are Shield bugs which are true bugs which are insects. Categories, dig?
Pretty much all shield bugs will bite you if you anger them enough, but kissing bugs bite your lip while you are sleeping without any provocation at all.
The only time I was ever bitten was on the St. Mary's fairgrounds decades ago. I woke up with a numb, swollen lip that became progressively more painful throughout the day. By midafternoon it hurt like hell.
This certainly seems like a good application for a very slow-release med or implantable capsule.
Great article Maggie. Had never heard of Chagas disease before. Might be travelling to Central America in the next few months and was interested to read that IDRC are having some success in Guatemala and Honduras, using a combination of preventative methods including plastering houses, building coops etc for livestock, nets, etc.
This bug has been haunting my sleep. I'm producing a film on a territory that is known for chagas disease. So it is really comforting to read your comment Ito, as no one on the production woke up with a painful bite during the last trip. (My partner woke up with a sore rib for week after the fist salad I served him for breakfast, after I realized that he left the tent open during the night)
The newest drug in the market is Benzinidazol, developed in 1974. It doesn't even work on all patients... it truly is a scary prospect
Interesting article. My grandfather died (some 20+ years ago) from a long, chronic digestive disease; I was very surprised to read in his death certificate that the cause of death was Chagas Disease, since I had just read some book about assassin bugs, and how Darwin had died from the same... Apparently, he did mention some disgusting bugs called "benchucas" (in Chile, assassin bugs are known as Vinchucas).
My grandfather probably was bitten while he was young in Argentina, where he worked in a very humid area. He spent a long time without any symptoms. Then the parasites attacked his digestive system, obstructing it, etc. He had a number of surgery procedures, pill treatment, etc. My guess is that doctors learned it was Chagas when it was too late... the disease is also infrequent here.
I took a course in parasitology in college.
Big mistake.
Also a big mistake would be doing an image search on elephantiasis, which is caused by tiny filarial worms invading your lymphatic system, the vector being mosquito bites.
Knowledge is fun!
Wow, talk about a blast from the past. When i was in 5th grade i did a really extensive essay/speech for my biology class. I went as far as to research all the current medical information available at the time, and i'm surprised i was remembering a lot of it as i was reading this.
Anyways, this disease is incredibly serious and it's good to know that finally some new effort is being put into it.
I did a volunteer program in 1998 when I was in highschool. We went to southern Bolivia and were "teaching" about Chagas and helping to improve peoples houses. We (in highschool spanish) were explaining as best we could about the desease and how you get it, and also explaining that by improving their houses it can help prevent having the bugs around if not prevent getting bit. We were plastering up the adobe bricked walls and painting them white, pouring concrete floors, and encouraging them to switch their thatch roofs to corrugated metal. I feel we made little impact but were able to help some families with their homes. We did other projects as well which made it hopefully more worth while.
I remember we had to sleep in little cocoons of mosquito netting so we would not get bitten--people thought we were nuts. That in conjunction with the Larium that we were taking for malaria made for some pretty intense nights--extremely explicit dreams about assassin bugs and who knows whatelse.
I am glad to see some acknowledgement about this desease after all of these years--hopefully the situation is getting better.
I only heard of Chagas Disease when I started donating blood. I had no idea what it was and I usually forgot about it by the time I could get a chance to look it up. Like most parasites, this one is disturbing as hell. Thanks for the information!
A note about shield bugs --- your basic shield bug (pentatomeoidea) is a sap sucker, a plant eater in other words. It may bite you but it won't suck your blood, and I haven't read anywhere that it carries the T. cruzi parasite.
"Os perigos do açaí produzido de forma artesanal podendo causar doença de chagas"
Bing
"The dangers of açaí produced artisanal chagas disease may cause.":
http://www.youtube.com/watch?v=J2yqdTofY-0
"Açaí faz 1 vítima de doença de Chagas a cada 4 dias na Amazônia"
Bing
"Açaí makes 1 victim of Chagas disease every 4 days in the Amazon"
http://www1.folha.uol.com.br/folha/cotidiano/ult95u321060.shtml
No Brasil o inseto é chamado de Barbeiro.
Bing
In Brazil the insect is called Barber.
http://pt.wikipedia.org/wiki/Doen%C3%A7a_de_Chagas
Nawel: As I mentioned above, it's unlikely Darwin even had Chargas, let alone died from it. His symptoms actually lessened as he aged and he lived a pretty long life. He died at age 73 after a massive heart attack.
Ack, shouldn't have done it. Brain scars! Ack!
Great article. Thank you for raising awareness of this disease Treatment administered during the acute stage of infection is usually effective. Once Chagas has progressed to the chronic stage, there is no effective treatment. Therefore, early detection and treatment, especially in young children, can have a significant impact on both patient outcome and health care costs. The unfortunate part of diagnosing Chags is that the incidence of Chagas is highest in rural areas where some serological tests (ELISA, PCR, IHA and IFA) are impractical to perform due to requirements for specialized instrumentation, cold storage and interpretation by a trained clinician. While not available in the United States, there is a rapid test that is feasible in such hot conditions. Chembio Diagnostic Systems, Inc.’s Chagas STAT-PAK® rapid assay is easy-to-perform, requires no cold chain storage, uses a minimal sample size and provides visual detection of antibodies to T. cruzi. It only takes 15 minute for results and it is very sensitive and specific in detecting the antibodies using a small amount of blood. More pressure needs to be put on governments to get these rapid tests to where it is most needed.
And, St. Mary's fairgrounds is where?
Kissing bugs are very common in the USA's arid west. Every summer there is a couple months when folks living in the desert in old cabins are lucky when they don't find one a day in the bedding. They are common around pack rat nests, and typically find a hiding place nearby when they find a host to feed from. Usually they hide under the bed. The bite is generally not painful, and may or may not swell. They are good sized insects over an inch long, and they make a lot more of a mess when you squash an engorged one than a mosquito does.
There are many, many types of shield bug, from stink bugs to assassin bugs to wheel bugs. Many are plant pests and some do significant crop damage. Many are carnivorous and some are beneficial to farmers. I believe they all have what the bug doctors call "piercing and sucking mouthparts" and consequently can deliver a painful bite if sufficiently motivated. The wheel bugs around here (East Coast USA) have such large stabbers that they have a groove in their chest plates it folds back into so they won't trip when they walk.
We call it "Kissing Disease" because once your infested, you can kiss your ass goodbye.
Dang, that's nasty stuff. Assassin bugs and shield bugs are also pretty common here on the East Coast of the US, especially in the autumn months. Assassin bugs are actually welcomed by many gardeners because they prey upon various garden pests. I've taken some very close macro shots and have never been bitten, but aside from getting up in their beady-eyed faces I avoid doing anything to antagonize them.
I'm glad people are working on finding a cure. But we need to be careful that we don't dismiss the continued need for "bug spray". The foolishness and fearmongering toward DDT set us back decades in controlling malaria, and killed and sicked untold millions of people in the process.
Thanks for bringing attention to this, truly creepy disease. One of the big problems, especially in the Amazon, is that the triatomine bugs that transmit Chagas disease fly into houses from palm trees in the area. A new study from Fiocruz Instituto Leônidas e Maria Deane, the Smithsonian Tropical Research Institute and the London School of Hygiene and Tropical Medicine figured out a way to estimate levels of Chagas disease in the Amazon, even when they can't figure out exactly where they are coming from. For more (and a picture of bugs on a trap), see our report on Eurekalert.
http://www.eurekalert.org/pub_releases/2010-03/stri-cds022310.php
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