[health-vn] Chagas disease: a new worldwide challenge : Nature : Nature [article and table of contents for issue]

[vern weitzel]

http://www.nature.com/nature/journal/v465/n7301_supp/full/nature09221.html
Chagas disease: a new worldwide challenge
José Rodrigues Coura & Pedro Albajar Viñas
Affiliations
Nature 465, S6–S7 (24 June 2010) doi:10.1038/nature09221
Published online 23 June 2010
Endemic Chagas disease began as a neglected disease of poor, rural and forgotten populations. Its spread from Latin America to non-endemic countries is a new worldwide challenge, say José Rodrigues Coura and Pedro Albajar Viñas.

Figures at a glance
left
  
right
Article tools
print
email
download pdf
download citation
order reprints
rights and permissions
share/bookmark
Human American trypanosomiasis (Chagas disease), along with its causal agent Trypanosoma (Schizotrypanum) cruzi, which was discovered by Carlos Chagas1 in Brazil in 1909, has existed in the Americas as an enzootic disease (that is, a disease of wild animals) for millions of years. Vectors mainly from the genera Triatoma, Panstrongylus and Rhodnius (Hemiptera; Reduviidae), but also from 12 other genera, have been transmitting the disease among animals for almost 10 million years. More than 150 species of triatomines (the disease vectors) and >100 species of mammals, mostly wild species, maintain T. cruzi infection in nature. The distribution of vectors and wild reservoirs of T. cruzi in the Americas extends from the United States to Argentina and Chile (latitudes 46° N to 46° S; see Who, how, what and where? on page S8). In total, 22 countries are endemic for enzootic disease in the Americas.

Humans arrived in the Americas between 26,000 and 12,000 years ago2, either overland (via the Bering Strait) or across the oceans. An increase in agricultural activities and domestication of animals ~10,000 years ago will have encouraged infection, although for thousands of years it continued to be mainly an anthropozoonosis (that is, an accidental infection of humans). Nevertheless, T. cruzi DNA has been found in mummies from northern Chile and southern Peru that are almost 9,000 years old3, and there is evidence of Triatoma infestans in human dwellings in pre-Columbian times, notably Inca and Chinchorro cultures, indicating gradual introduction of domestic transmission. Over the past 200–300 years, with progressive deforestation for agriculture and livestock rearing, and the opening of overland transportation routes (railroads and highways), triatomines gradually lost their primary food source of wild-animal blood, while at the same time having more opportunities to spread. They adapted to areas surrounding human dwellings and to the dwellings themselves, feeding on the blood of domestic animals and humans. In this manner, a new cycle of infection was established, and Chagas disease became a zoonosis4 (that is, a disease that transmits between animals and humans endemically; see life-cycle image in Chagas disease 101 on page S4).

Chagas disease in Latin America
Endemic Chagas disease in Latin America began as a neglected disease of poor, rural and forgotten human populations. The wild triatomines progressively adapted to the domestic environment, living in cracks in the mud walls and roofs of huts. Some such dwellings can shelter up to 14,000 triatomines, feeding on human blood and transmitting T. cruzi. Millions of people have been infected, have developed the disease and have even died — without the possibility of getting a diagnosis, let alone medical assistance. Significant foci of domestic infestation might still be found, especially in areas of Bolivia, which has the highest prevalence rate of human infection (see Who, how, what and where? on page S8), and the 17 other Latin American countries that have not controlled vector transmission.

Progressive urbanization of the rural population in Latin America, mainly since the 1940s, has made Chagas disease an important urban medical and social problem. This has introduced new risks, such as the possibility of T. cruzi transmission through blood transfusion. In 1960, we estimated that as many as 6,000 and 10,000 cases of Chagas disease each year were caused by receiving an infected blood transfusion in Rio de Janeiro and São Paulo, respectively, which are the two largest cities in Brazil. In the same year, a World Health Organization (WHO) expert committee estimated 7 million cases per year due to blood transfusion in Latin America as a whole. To assess the scale of the problem, we performed a serological survey of two blood banks in Rio de Janeiro from 1961 to 1963, covering 4,595 blood donors. We found that 1.8% of samples were serologically positive for T. cruzi infection. We were able to trace 58 infected blood donors and 24 recipients of infected blood, and found that six of the recipients had acquired Chagas disease because of their transfusion. Such findings helped change policy and practice: now the blood banks are fully controlled in Brazil and in many — although not all — other Latin American countries. Infected blood is still a great problem in countries such as Bolivia, where, in cities like Santa Cruz de la Sierra and Cochabamba, up to one-half of blood donors can be infected with T. cruzi.

Long-term infection can have different health risks. One of the key problems is chagasic heart disease, which occurs with higher frequency in people aged 20–59 years — at the most productive time of their lives — and, in endemic areas, represents the main cause of disability and mortality. From the early 1960s to the late 1980s, we followed 510 Chagas disease patients in Rio de Janeiro who originated from 15 different Brazilian endemic states. Among them, 39.9% were asymptomatic, 52.1% had chagasic heart disease, and 14.3% had digestive forms of megaoesophagus and megacolon (including 6.3% who had both cardiac and digestive forms; Fig. 1). For the past 30 years, we have expanded our study, working in endemic areas across Brazil, in the southeast (Minas Gerais), northeast (Paraíba and Piauí), west (Mato Grosso do Sul) and Amazon regions, following hundreds of Chagas disease patients. We confirmed our previous hypothesis about the great regional diversity of Chagas disease morbidity. The disease is more severe in Minas Gerais and Piauí, and moderate in Paraíba, Mato Grosso do Sul and the Amazon region. Among other reasons, this is probably related to the type of T. cruzi and its infection burden. In the Amazon region, we did not find digestive forms, which were similarly absent in areas further north4, 5.

Figure 1: Acute and chronic phases of Chagas disease.
 
a, Trypanosoma cruzi in the blood of an acute case. b, Scar in the cardiac tissue of a chronic case. c-e, Dilatation of the heart (c), oesophagus (d) and colon (e) in chronic cases of Chagas disease.

J. R. COURA

Full size image (73 KB)
Figures index
Next figure
Regional variation in Chagas disease
As well as severity and nature of chronic infection, there are other regional differences in Chagas disease-transmission cycles, prevalence and control programmes, which can be arranged into four categories.

In Argentina, Bolivia, Brazil, Chile, Ecuador, Paraguay, Peru, Uruguay and Venezuela, Chagas disease is characterized by the presence of domestic, peridomestic and wild cycles, with zones of high prevalence of human infection, and the presence of myocardiopathy and digestive abnormalities (with the exception of Venezuela). Well-established vectorial and transfusional transmission controls exist (with 100% coverage of blood banks, except in Bolivia).

In Colombia, Costa Rica, Ecuador, El Salvador, Guatemala, Honduras, Nicaragua and Panama, Chagas disease similarly has domestic, peridomestic and wild cycles, and patients present with chronic Chagas disease cardiopathy but not digestive abnormalities. Vector and transfusional transmission controls exist, but are more recent.

In Belize, French Guiana, Guyana, Suriname, Mexico and even the United States, Chagas disease primarily has a wild cycle, and there is limited available information about acute and chronic clinical manifestations. Vectorial and transfusional transmission controls are at an incipient stage.

Finally, there are non-endemic countries that have significant population exchange with Latin America, mainly in the form of migration. Here, Chagas disease is a new challenge.

Chagas disease abroad: a new challenge
Non-infected triatomine vector species have been found along the coastal regions of Africa, the Middle East, Southeast Asia and the western Pacific regions, having spread via maritime trade from Latin America from as early as the sixteenth century. In fact, the first entomological description of the vector was made by the Swedish scientist De Geer (1773). The vector might also be spread along air transportation routes in passengers' baggage, thereby increasing the risk of transmission outside of Latin America6. The first triatomine, described by De Geer as Cimex rubrofasciatus and today known as Triatoma rubrofasciata, transmits Trypanosoma lewisi among rats, and is not currently a risk to humans.

The T. cruzi parasite can travel with population movements from endemic to non-endemic countries such as North America (United States and Canada), the western Pacific region (particularly Japan and Australia) and, more recently, Europe (mainly Belgium, Spain, France, Italy, the United Kingdom and Switzerland, and to a lesser extent Germany, Austria, Croatia, Denmark, the Netherlands, Luxemburg, Norway, Portugal, Romania and Sweden). It has been estimated that there are now >300,000 individuals infected with T. cruzi in the United States, >5,500 in Canada, >80,000 in Europe and in the western Pacific region, >3,000 in Japan and >1,500 in Australia7, 8, 9(Fig. 2).

Figure 2: Migration routes from Latin America and estimation of the total number of infected individuals in non-endemic countries.
 
J. R. COURA

Full size image (139 KB)
Previous figure
Figures index
These population movements have started to create new epidemiological, economic, social and political challenges, as T. cruzi has spread worldwide. With the absence of natural vectors, the main threats are from infected blood transfusions and vertical transmission from mother to child, with organ transplantation and laboratory accidents making up a lower risk pool. The number of cases of infection among people travelling to Latin America for tourism or work reasons, and even among adopted children, is also significant. All this shows the need to improve information and surveillance systems at national and supranational levels, implement medical care for patients with Chagas disease in non-endemic countries, intercept vertical transmission, implement additional controls for blood banks and organ transplantation, and include the differential diagnosis for Chagas disease within travel medicine10. In addition to the medical, social and economic factors, the spread of Chagas disease poses a political problem: many developed countries rely on migrants to form part of the labour force, yet are not prepared for the challenges they bring, notably the need to organize infrastructure, prepare blood banks to screen millions of blood donors, perform donor and recipient screening for organ transplantation, screen women of child-bearing age who are at risk of being infected and their children, organize out-patient clinics to care for these patients, and train personnel to diagnose and treat Chagas disease.

Chagas disease has become more than simply a zoonotic disease that mainly affects the rural poor in Latin America: it is a worldwide concern that can have severe consequences for human health over the long term. If it is not taken seriously, it could become a major threat to global health.

References
Author information
References Author information	 Comments
Affiliations
José Rodrigues Coura (MD, PhD) is emeritus professor at the Federal University of Rio de Janeiro, and head and chairman of the Laboratory of Parasitic Diseases, Oswaldo Cruz Institute, Fundação Oswaldo Cruz (Fiocruz), Ministry of Health, Brazil 
coura at ioc.fiocruz.br
Pedro Albajar Viñas (MD, PhD) is medical officer and coordinator of the WHO/Neglected Tropical Diseases (NTD)/Chagas Disease Programme 
albajarvinasp at who.int


From: "Ruggiero, Mrs. Ana Lucia (WDC)" <ruglucia at PAHO.ORG>
Date: 20 August 2010 6:05:10 AM PDT
To: EQUIDAD at LISTSERV.PAHO.ORG
Subject: [EQ] Outlook: Chagas Disease
Reply-To: "Equity, Health & Human Development" <EQUIDAD at LISTSERV.PAHO.ORG>

Outlook: Chagas Disease

Nature - Vol. 465, No. 7301 suppl. ppS3-S22 (24 June 2010) - DOI:doi:10.1038/465S3a

Website: http://www.nature.com/nature/outlook/chagas/index.html

“…..Chagas disease is one of the most neglected of the tropical diseases, yet millions of people are infected with it. There are only two available drugs to treat it, both of which are more than 40 years old and neither of which is ideal.

As the global population has become more internationally mobile, Chagas disease has spread from Latin America to become a worldwide threat.

This Outlook highlights some of the progress in understanding and treating Chagas disease over its 101 years of recent history and outlines the challenges still to be met….”

Outlook Editorial

Chagas disease — Michelle Grayson
Nature 465, S3 (24 June 2010) doi:10.1038/465S3a Full Text | PDF

“….Chagas disease is arguably the archetypal neglected disease. Millions of people — the vast majority in Latin America — are infected, yet it is seldom discussed. It has struggled to achieve even a fraction of the notoriety of other neglected diseases, such as malaria. Its prevalence in immigrants to Spain, Portugal, the United States and other parts of the world has gone largely unnoticed. Even those who live in endemic areas are rarely aware of it…”

Feature

Chagas disease 101 — Julie Clayton
Nature 465, S4—S5 (24 June 2010) doi:10.1038/nature09220 Full Text | PDF

‘…It is 101 years since Carlos Chagas discovered the parasite responsible for the disease that now bears his name. What progress has been made since this discovery? Here Julie Clayton gives the low-down on Chagas disease…”

Opinion

Chagas disease: a new worldwide challenge — José Rodrigues Coura & Pedro Albajar Viñas
Nature 465, S6—S7 (24 June 2010) doi:10.1038/nature09221

Full Text | PDF

 
Feature

Who, how, what and where? — Nature 465, S8—S9 (24 June 2010) doi:10.1038/nature09222
Full Text | PDF

 
Feature

Country by country — Anna Petherick
Nature 465, S10—S11 (24 June 2010) doi:10.1038/nature09223

Full Text | PDF

 
Feature

Chagas disease: pushing through the pipeline — Julie Clayton
Nature 465, S12—S15 (24 June 2010) doi:10.1038/nature09224

Full Text | PDF

 
Feature

The promise of T. cruzi genomics — Julie Clayton
Nature 465, S16—S17 (24 June 2010) doi:10.1038/nature09225

Full Text | PDF
 
Feature

Chagas disease in the Chaco — Anna Petherick
Nature 465, S18—S20 (24 June 2010) doi:10.1038/nature09226

Full Text | PDF

 
Feature

Campaigning for Chagas disease — Anna Petherick
Nature 465, S21—S22 (24 June 2010) doi:10.1038/nature09227

Full Text | PDF
 
News and Views

Parasitology: Triple genome triumph —  Declan Butler
Nature 436, 337—337 (21 July 2005) doi:10.1038/436337b

Full Text | PDF
 
Commentary Immunology south of the equator in the Americas —

Gabriel A. Rabinovich, Alexis M. Kalergis, Norberto W. Zwirner & Wilson Savino
Nature Immunology 9, 1087—1090 (2008) doi:10.1038/ni1008-1087

Abstract | Full Text | PDF
 
Perspective

Trypanosoma cruzi surface mucins: host-dependent coat diversity —
Carlos A. Buscaglia, Vanina A. Campo, Alberto C. C. Frasch & Javier M. Di Noia
Nature Reviews Microbiology 4, 229—236 (March 2006) doi:10.1038/nrmicro1351

Abstract | Full Text | PDF
 
Article

Drug-induced cure drives conversion to a stable and protective CD8+ T central memory response in chronic Chagas disease —
Juan M. Bustamante, Lisa M. Bixby & Rick L. Tarleton
Nature Medicine 14, 542—550 (20 April 2008) doi:10.1038/nm1744

Abstract | Full Text | PDF
 
Perspective

The Trypanosoma cruzi-host-cell interplay: location, invasion, retention — Luciana O. Andrade & Norma W. Andrews
Nature Reviews Microbiology 3, 819—823 (9 September 2005) doi:10.1038/nrmicro1249

Abstract | Full Text | PDF
 
 
 

 *      *     *
This message from the Pan American Health Organization, PAHO/WHO, is part of an effort to disseminate
information Related to: Equity; Health inequality; Socioeconomic inequality in health; Socioeconomic
health differentials; Gender; Violence; Poverty; Health Economics; Health Legislation; Ethnicity; Ethics;
Information Technology - Virtual libraries; Research & Science issues.  [DD/ KMC Area]
“Materials provided in this electronic list are provided "as is". Unless expressly stated otherwise, the findings
and interpretations included in the Materials are those of the authors and not necessarily of The Pan American 
Health Organization PAHO/WHO or its country members”.
------------------------------------------------------------------------------------
PAHO/WHO Website
Equity List - Archives - Join/remove: http://listserv.paho.org/Archives/equidad.html 
Twitter http://twitter.com/eqpaho






IMPORTANT: This transmission is for use by the intended
recipient and it may contain privileged, proprietary or
confidential information. If you are not the intended
recipient or a person responsible for delivering this
transmission to the intended recipient, you may not
disclose, copy or distribute this transmission or take
any action in reliance on it. If you received this transmission
in error, please dispose of and delete this transmission. 

Thank you.


-- 
Vern Weitzel (Mr.) BSc, BA, MA, M Env Man & Dev
<vern.weitzel at gmail.com> <vernweitzel at me.com>

ANU/AVSL eMail Lists: http://coombs.anu.edu.au/~vern/forum.html
NGO RC eMail Lists: http://ngocentre.org.vn/mailman/listinfo

Address to August 2010: 2724 NE 24th St, Renton WA 98056-8321 USA
tel: +1 (425) 228-4513 mob: +1 (206) 3-9999-81
--
Viet Nam: 1st stairwell, apartment 504-505, A4 Giang Vo,
Ba Dinh, Ha Noi [Ngoc Khanh St, near Kim Ma St] tel: +84 (4) 3846-1751
Australia: PO Box 4013, Ainslie, ACT 2602 [post box only]
Skype: vernweitzel      Facebook: vern.weitzel
IF I DO NOT RESPOND IN A REASONABLE TIME, PLEASE RESEND YOUR MESSAGE

"Kindness heals the wounds of a lifetime"

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mailman.anu.edu.au/pipermail/health-vn/attachments/20100820/182f8ad6/attachment.html