Monday, November 23, 2009
Sunday, November 22, 2009
Why do I care about Chagas?
When I traveled to rural Honduras in the summer of 2008, I had never heard of Chagas disease. By the end of my trip, I was terrified of Chagas, even though I slept underneath a mosquito net in a concrete building. The gruesome mode of transmission was enough to scare me, as horror story might, but it was the silent progression of the disease that most frightened me. I was volunteering with a clinic, and most of the homes we visited were adobe or wood homes that the kissing bug loves to infest. Surely a huge segment of the population had been infected, and wouldn’t know it for years to come, until suddenly organ failure ripped them from their families.
The community we were in was very isolated from most medical care and much medical knowledge. The town our little ill-equipped clinic was in was located literally at the end of the road (which was unpaved). To get to the nearest hospital, a three-hour drive over bumpy, unpaved roads was required. The nearest big city was six or seven hours away. Villagers hiked sometimes for hours from their unmapped, tucked-away homes just to come to our clinic. I don’t know if our clinic checked people regularly for Chagas (I believe it did not), but even if it did, treatment would be nearly impossible, since the clinic was not equipped for it, and the villagers were too poor to pay much for it. Add on top of these difficulties a cultural distrust of medicine, and the toxic effects and limited efficacy of available drugs, and the challenge Chagas poses worsens.
We saw multiple children there with one red, puffy eye. We figured they had pink-eye or something innocuous until we found out that this is Romana’s sign, which sometimes pops up in children who have been infected via the eye by the Chagas parasite. Their parents, oblivious to the meaning of such a seemingly harmless symptom, and busy tending to a whole family brood, were not even alarmed enough to ask us about it. While they lived in ignorance, and we stood essentially unable to help, the disease worked silently to deteriorate these kids’ organs.
Chagas poses a huge public health challenge for some of the poorest countries in Latin America. Largely overlooked by the international community (although its spread into the U.S. blood supply may increase interest), the disease kills thousands every year while drug companies try only half-heartedly to help. While non-profits have played a large role in spurring research into treatment, and improving patient care and teaching, they do not have the resources necessary to effect large-scale improvements in public health. Considerable money needs to be invested in methods of prevention (for example, knocking down adobe houses and building concrete ones instead, or genetically modifying the disease vectors), awareness (public health outreach efforts to teach communities about how to identify and fight infestations), and treatment (developing better drugs or vaccines, or improving stem cell therapy). Yet, while Chagas continues to affect only the poorest citizens of the poorer countries, this money appears unobtainable, and the disease's horror will persist.
- Joanna Sharpless
A Neglected Infection of Poverty
Dr. Sheba Meymandi discusses her attempts to raise Chagas awareness.
Developing World's Parasites, Disease Hits US
The Wall Street Journal
Stephanie Simon and Betsy McKay
22 August 2009
To complement some other posts focusing on the issue of Chagas in a broader sense, here's a story of the disease through the eyes of one woman doctor battling the disease in poor communities in California.
Dr. Sheba Meymandi, a physician who runs the first Chagas clinic opened in the U.S., has committed her life to improving health in underserved communities where Chagas disease runs rampant. One weekend per month, Dr. Meymandi travels by car to impoverished Latino communities near the LA clinic and uses churches as makeshift clinics in order to test and treat patients for Chagas.
One of her biggest challenges is convincing people to get tested, as many don’t care to be tested for an “exotic” disease. Another problem is the bad reputation of the treatment regimen; the treatment therapy is associated with a slew of unfortunate side effects including memory loss and lack of sensation in the limbs. Many illegal immigrants are also unwilling to obtain treatment because they don’t want to draw attention to themselves.
Dr. Meymandi asserts that Chagas should no longer be considered an exotic disease, as it is highly prevalent particularly in shanty towns lining the U.S.-Mexico border where overcrowding, malnutrition, poor sanitation, and much animal-to-human contact are present. Poor drainage systems are cesspools for breeding of Chagas bugs, and a lack of window screens allows for easy transmission to humans.
Raising awareness of the disease burden has become a major goal, and already health care legislation is pending for a full report to congress on Chagas along with several other diseases dubbed (very appropriately) “neglected infections of poverty”. This article and video gives us another look at issues raised in many other posts in this blog regarding the social causes of Chagas, the extremely poverty associated with Chagas, and public's lack of knowledge on the issue of Chagas. Yet examining the issue through the eyes of one doctor who has made battling Chagas her life's work gives us insight that we can't see in other news reports. We can use the issue of Chagas as a lens through which we can view broader controversies in society, such as debates about healthcare and the health and human rights (or lack therof) in illegal immigrant populations in the United States. Decisions made on these broader issues will greatly influence the future impact of Chagas disease in the U.S.
Find the article at http://online.wsj.com/article/SB12
5090339313750961.html
CD: Acute and Chronic Phase
Flow chart showing phases of CD, and at what phases which symptoms present
Chagas R&D
Isabela Ribeiro et al, 2009
Public Library of Science Journal- Neglected Tropical Diseases
This article discusses the need for new and improved treatments for Chagas disease, and sets up short term, medium term, and long term goals for this process. Shorter term goals include better use of existing treatments through new formulations and expanding access. Longer term goals include development of new drugs. The article discusses the 2 current treatments available (that have been mentioned in previous articles)- nifurtimox and benznidazole. However, these are limited to treating the acute phase of the disease, not the chronic phase. The article mentions that no promising new drugs are expected anytime soon, although according to other articles there is one- Ravuconazole, discovered and developed by Eisai Co.
There are many barriers to developing treatments, including the fact that there is little standardization among the protocols and parasites used by researchers in assays. Thus reproducibility has been difficult to achieve. Few rigorous trials have been conducted in CD, particularly to test drug efficacy in patients with chronic CD, since such patients often do not present any clinical disease manifestation until a very advanced stage. CD research is often deemed “too difficult” by many.
One development to help deal with these issues is the creation of non-profit product development partnerships (PDPs) which work to fill in the gaps for neglected diseases. These PDPs offer a different model, since R&D is no longer financed by a product’s sale price. A PDP is currently working on developing a better CD portfolio to address the needs of patients. They aim to deliver more effective treatment for acute, indeterminate, and chronic CD and are working on a pediatric formulation of benznidazole.
http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0000484
Breakthroughs in the Quest for a Vaccine
Researchers at UGA provide first look at protein expression in Chagas disease-causing parasites
Innovations Report
15/07/2005
Major advances have been made in elucidating the genetic processes of Trypanosoma cruzi, the parasite that causes Chagas. This article highlights findings from a study at the University of Georgia, where a research team successfully conducted a survey of protein expression in the four lifecycle stages of the parasite. Their results show distinct protein expression abundance and specificity during different stages of the life cycle.
The research is useful because it could hold the key to a new drug or vaccine target. As touched on in previous posts, current treatments for Chagas aren’t always effective and no vaccine has yet been developed. The problem with developing a vaccine lies in the complexity of this four-stage parasite lifecycle, as it complicates attempts to create an effective therapy that can target and eliminate the parasite in all its different stages. But by examining protein expression along with the recently developed gene map, scientists may be able to make decisions on the viability of specific large gene families as candidates for a vaccine.
This article shows thad advances in bioinformatics such as these are integral to drug and vaccine development for Chagas. Yet we already know that the biggest barrier to Chagas’ vaccine development is not scientific. As Chagas disease afflicts mainly impoverished peoples, there is little financial incentive for drug manufacturers to work invest in R&D for a treatment. Public-private partnerships and market commitments need to be formed in order to ensure that the different private and public goals are aligned towards finding a vaccine.
Nevertheless, these genetic breakthroughs are a hopeful sign in the pursuit of a vaccine for a life-threatening disease that afflicts more than 20 million people around the globe.
Article found at http://www.innovations-report.com/html/reports/life_sciences/report-46584.html
More on Buggy Blood: Transfusing the Disease
An ongoing map record showing confirmed cases of donor blood being infected with Chagas disease 07-09. Put out by the AABB (see below). These AABB labs account for 65% of the total blood collected in the U.S.
“Blood Donations in the U.S. testing positive for Chagas’ Disease”
Associated Content
21 Oct 2007
Is blood donated to aid people in life-saving transfusions safe from being buggy? Probably, according to the CDC. Yet discoveries of blood donations infected with the Chagas parasite have highlighted not only the higher-than-anticipated prevalence of Chagas in the U.S. but also the need for better screening to ensure blood donation recipients aren’t getting infected. We know from the last "Buggy Blood" post that blood donations in the U.S. are infected with the Chagas parasite, but another eye-opening article really elaborates on the extent of the problem, the barriers to better screening, and what steps have been taken to ensure blood donations are safe.
An October ‘07 article recounts the release of info from the American Association of Blood Banks (AABB) indicating that about 241 blood donations in the U.S. had tested positive for Chagas disease since the advent of an FDA-licensed blood detection method in January ‘07. Within the year Chagas-positive blood donations had been spotted in 34 states, prompting Dr. James Maguire, former head of the CDC’s parasitic diseases division, to describe the results as “surprising”.
Yes, the results suggest the horrifying possibility that an unknown number of patients receiving untested blood donations may have been exposed to and possibly infected by transfusions containing the deadly T.cruzi parasite. Blood safety experts and the Red Cross were looking into new disease cases that may have involved transmission via blood transfusions with infected blood, but details were not disclosed in the article. Experts estimated that roughly 70% of blood donations were being screened for Chagas--- meaning that about a third of all blood donations in the country are being used in transfusions without being screened for infection. Meaning that for a third of blood donations, you run the risk, if not minuscule, of being infected with a potentially fatal disease without even knowing it.
…..yeah, that’s not very reassuring to me either. And the 2009 CDC Q&A factsheet on screening blood donations for Chagas is even less helpful. In response to a blood donors’ question “Will I be tested automatically (for Chagas)?” the CDC states “Probably. Most blood banks are testing for Chagas disease”. I’m guessing any person about to receive a blood transfusion would prefer the answer regarding the infection status of the blood they’re receiving to be a little more definitive than “probably”.
The good news from this: we now possess an effective blood test for detecting Chagas’ (the T.cruzi ELISA test, developed by Ortho boasts 100% sensitivity and 99.99% sensitivity), and it seems that we have taken the first steps towards developing a biovigilance network and screening blood for Chagas in blood donors as a medical standard. Plus, the donors who test positive are now becoming aware of their own infection status, allowing for them to take any precautionary measures and contributing to the growing pool of evidence on the true prevalence of Chagas in the U.S. Info put out by the AABB includes an ongoing biovigilance map where you can see confirmed cases where donor blood tested positive for Chagas.
Building on the last "Buggy Blood" post, this article really is eye-opening in terms of infected blood donations. Yet more emphasis needs to be put on screening ALL donors for Chagas, rather than just some. How can we do this? Educating the public and publicizing the issue.
CDC factsheet http://www.cdc.gov/chagas/factsheets/screening.html
AABB Biovigiliance Network http://www.aabb.org/Content/Programs_and_Services/Data_Center/Chagas
Article: http://www.noblood.org/news-hot-topics-such-hepatitis-c-sars-aids/3907-us-blood-donations-testing-positive-chagas-disease.html