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Chagas' disease—an epidemic that can no longer be ignored
Editorial
To coincide with the World Congress on Cardiology in Barcelona next month, this week’s Lancet focuses on matters of the heart. We share the bad news of the global effects of tobacco in the INTERHEART study, suggest that ACE inhibitors can help prevent abdominal aortic aneurysm, and present a cost analysis of management of cardiovascular illness in developing countries. A recent Comment highlighted that training in South Africa mimics that in developed countries and does not reflect the importance of non-ischaemic cardiac diseases, such as rheumatic fever. Likewise, while a Comment in this week’s issue emphasises the importance of future increasing cardiovascular risk in Latin America, there is a pressing, highly prevalent danger endemic to Latin America which the world’s research community continues to ignore—Chagas’ disease. Caused by infection with the parasite Trypanosoma cruzi, Chagas’ disease kills at least 50 000 people every year. For most, the dominant cause of death is end-stage congestive cardiac failure. An estimated 18 million people are chronically infected with the parasite and about 100 million are at risk of infection in 21 countries in Latin America—about 25% of the region’s population. The parasite is transmitted to human beings by bloodsucking insects that usually live in cracks in the walls of mud and straw houses common to poor rural and urban communities. It can also be transmitted through blood transfusion, and mother-to-child transmission. The infection progresses in stages. The acute stage largely passes unnoticed as the symptoms are similar to those of most common childhood infections—fever, swollen lymph glands, or an enlarged liver or spleen. About 20–30% of those infected will go on to develop the chronic form of the disease up to 20 years after they first contracted it. The cardiac form comprises about 40% of chronic cases and treatment of resulting arrythmias, cardiomyopathy, and cardiac failure is symptomatic. The conventional medical model of prevention, diagnosis, and treatment is fraught with difficulties in Chagas’ disease. Prevention via vector control is the main focus of national country programmes but it is hugely expensive—for example, the cost of a 10-year control programme in Ecuador is estimated at around US$30 million—and has had mixed success because of insect resistance. Most importantly, putting all resources into www.thelancet.com Vol 368 August 19, 2006
prevention does nothing for the millions of people already infected. Treatment seems to play no part in current health strategies of disease control. Infection can only be diagnosed by serum sampling but there is little confidence in the quality of the rapid diagnostic tests currently available. The triazole derivatives, nifurtimox and benznidazole, are the only existing drugs to treat Chagas’ disease. Neither drug is ideal because they are not effective in the chronic phase, have serious sideeffects, such as neurotoxicity, and need to be given for 30–60 days under specialised medical supervision. Also, there are substantial regional variations in efficacy due to naturally resistant T cruzi strains. Children younger than 12 years are usually the only ones to receive treatment. They have a greater chance of benefiting as they are unlikely to have developed chronic symptoms. However, there are no paediatric formulations, no specific blood tests to show that the patient has been cured, and no vaccine in the pipeline. So in summary, there is a fatal endemic disease in Latin America that causes death by cardiac failure. It only affects the poor. It has no initial symptoms. It becomes chronic in many but there is no way of telling in whom. It cannot be diagnosed with confidence. There is no vaccine or effective treatment, and no test to demonstrate cure. Would this unacceptable situation be any different if Chagas’ disease was endemic to a richer continent? But there may be some hope. Last year, 200 scientists from around the world deciphered the genome of T cruzi, which may lead to new treatments for Chagas’ disease. Because of the lack of interest from big drug companies in the world’s most neglected diseases, the Drugs for Neglected Diseases Initiative—a not-for-profit organisation—has concentrated its efforts on finding more effective triazole derivatives to treat Chagas’ disease. For example, posaconazole may have potential benefits. It has recently shown promise as a systemic antifungal agent but so far, the company producing the drug, Schering-Plough, is not interested in clinically developing this compound for Chagas’ disease. So what is needed for this most neglected of neglected diseases with profound cardiac consequences to gain more interest from the world research community? A full and frank discussion at the upcoming World Cardiology Congress would be a good place to start. ■ The Lancet
We do not have the rights to reproduce this image on the web.
See Articles pages 647, 659, and 679 See Comment page 625
For Comment showing that training in South Africa does not reflect the importance of non-ischaemic cardiac diseases see Lancet 2006; 367: 1884–85 For Schering-Plough’s lack of interest in developing posaconazole for Chagas’ disease see Newsdesk Lancet Infect Dis 2005; 8: 470–471
619
Science Photo Library
Chagas’ disease—an epidemic that can no longer be ignored
To coincide with the World Congress on Cardiology in Barcelona next month, this week’s Lancet focuses on matters of the heart. We share the bad news of the global effects of tobacco in the INTERHEART study, suggest that ACE inhibitors can help prevent abdominal aortic aneurysm, and present a cost analysis of management of cardiovascular illness in developing countries. A recent Comment highlighted that training in South Africa mimics that in developed countries and does not reflect the importance of non-ischaemic cardiac diseases, such as rheumatic fever. Likewise, while a Comment in this week’s issue emphasises the importance of future increasing cardiovascular risk in Latin America, there is a pressing, highly prevalent danger endemic to Latin America which the world’s research community continues to ignore—Chagas’ disease. Caused by infection with the parasite Trypanosoma cruzi, Chagas’ disease kills at least 50 000 people every year. For most, the dominant cause of death is end-stage congestive cardiac failure. An estimated 18 million people are chronically infected with the parasite and about 100 million are at risk of infection in 21 countries in Latin America—about 25% of the region’s population. The parasite is transmitted to human beings by bloodsucking insects that usually live in cracks in the walls of mud and straw houses common to poor rural and urban communities. It can also be transmitted through blood transfusion, and mother-to-child transmission. The infection progresses in stages. The acute stage largely passes unnoticed as the symptoms are similar to those of most common childhood infections—fever, swollen lymph glands, or an enlarged liver or spleen. About 20–30% of those infected will go on to develop the chronic form of the disease up to 20 years after they first contracted it. The cardiac form comprises about 40% of chronic cases and treatment of resulting arrythmias, cardiomyopathy, and cardiac failure is symptomatic. The conventional medical model of prevention, diagnosis, and treatment is fraught with difficulties in Chagas’ disease. Prevention via vector control is the main focus of national country programmes but it is hugely expensive—for example, the cost of a 10-year control programme in Ecuador is estimated at around US$30 million—and has had mixed success because of insect resistance. Most importantly, putting all resources into www.thelancet.com Vol 368 August 19, 2006
prevention does nothing for the millions of people already infected. Treatment seems to play no part in current health strategies of disease control. Infection can only be diagnosed by serum sampling but there is little confidence in the quality of the rapid diagnostic tests currently available. The triazole derivatives, nifurtimox and benznidazole, are the only existing drugs to treat Chagas’ disease. Neither drug is ideal because they are not effective in the chronic phase, have serious sideeffects, such as neurotoxicity, and need to be given for 30–60 days under specialised medical supervision. Also, there are substantial regional variations in efficacy due to naturally resistant T cruzi strains. Children younger than 12 years are usually the only ones to receive treatment. They have a greater chance of benefiting as they are unlikely to have developed chronic symptoms. However, there are no paediatric formulations, no specific blood tests to show that the patient has been cured, and no vaccine in the pipeline. So in summary, there is a fatal endemic disease in Latin America that causes death by cardiac failure. It only affects the poor. It has no initial symptoms. It becomes chronic in many but there is no way of telling in whom. It cannot be diagnosed with confidence. There is no vaccine or effective treatment, and no test to demonstrate cure. Would this unacceptable situation be any different if Chagas’ disease was endemic to a richer continent? But there may be some hope. Last year, 200 scientists from around the world deciphered the genome of T cruzi, which may lead to new treatments for Chagas’ disease. Because of the lack of interest from big drug companies in the world’s most neglected diseases, the Drugs for Neglected Diseases Initiative—a not-for-profit organisation—has concentrated its efforts on finding more effective triazole derivatives to treat Chagas’ disease. For example, posaconazole may have potential benefits. It has recently shown promise as a systemic antifungal agent but so far, the company producing the drug, Schering-Plough, is not interested in clinically developing this compound for Chagas’ disease. So what is needed for this most neglected of neglected diseases with profound cardiac consequences to gain more interest from the world research community? A full and frank discussion at the upcoming World Cardiology Congress would be a good place to start. ■ The Lancet
We do not have the rights to reproduce this image on the web.
See Articles pages 647, 659, and 679 See Comment page 625
For Comment showing that training in South Africa does not reflect the importance of non-ischaemic cardiac diseases see Lancet 2006; 367: 1884–85 For Schering-Plough’s lack of interest in developing posaconazole for Chagas’ disease see Newsdesk Lancet Infect Dis 2005; 8: 470–471
619
Science Photo Library
Chagas’ disease—an epidemic that can no longer be ignored