Citation: Dumonteil E, Herrera C, Martini L, Grijalva MJ, Guevara AG, Costales JA, et al. (2016) Chagas Disease Has Not Been Controlled in Ecuador. PLoS ONE 11(6): e0158145. https://doi.org/10.1371/journal.pone.0158145
Editor: Herbert B. Tanowitz, Albert Einstein College of Medicine, UNITED STATES
Received: March 8, 2016; Accepted: June 11, 2016; Published: June 28, 2016
Copyright: © 2016 Dumonteil et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The authors have not received any funding for this work.
Competing interests: ED recently published an article about Chagas disease in Ecuador, whose conclusions differ from those reported in the PLOS ONE article.
A recent study by Cartelle Gestal et al. reported an analysis of data from the Ministry of Public Health on the epidemiological situation of neglected tropical diseases in Ecuador . Based on a misleading definition of Chagas disease cases not corresponding to that of the Ministry of Public Health , the authors concluded that the government had mounted successful control campaigns, and as a result Chagas disease (among others) had been effectively controlled as no cases in children under age five had been reported since 2009. Ecuador is thus identified as one of the first countries to control Chagas disease.
While we certainly agree that efforts have been made in terms of Chagas disease surveillance and control campaigns in Ecuador, a more comprehensive analysis of available data, from both the Ministry of Public Health and the literature, provides a very different picture, and the claim that Chagas disease is controlled made by Cartelle Gestal et al. seems largely inadequate and sends an equivocal message which can undermine current control efforts. As mentioned in this study, the Chagas disease control program in the country was formally established in 2003–2004, in response to recommendations from a technical consultation through PAHO/WHO  and field studies [4,5]. This consultation and data provided a baseline to prioritize activities. It reported a national seroprevalence of Trypanosoma cruzi infection of 1.38%, corresponding to 165–170,000 seropositive patients in the country. Three regions were prioritized: the coastal region (seroprevalence of 1.99%), the Amazon region (1.75%) and the southern highlands (0.65%). The incidence was estimated at 36 cases/100,000 inhabitants/year, resulting in 4,400 new cases each year .
Today, the most recent estimates from the WHO suggest the presence of nearly 200,000 seropositive patients and a current incidence of 14 cases/100,000 inhabitants/year . An in depth analysis of the complete records from the Ministry of Public Health from 2004–2014, indicates a total of 915 reported human cases in the country, with a major increase over the years followed by a decrease in the past two years . This increase reflects the efforts at improving the epidemiologic surveillance program, but it is clear that there is still significant underreporting of cases in the country. Indeed, several independent and recent seroprevalence studies in different regions and communities point out relatively high levels of seroprevalence of T. cruzi infection (ranging from 0.6 to 13.3%), and persistent active parasite transmission, as evidenced by the detection of seropositive children [8–12]. Additionally, there are reports of Chagas disease cases in regions where the Ministry of Public Health has no records of patients, further highlighting current underreporting [5,11,12]. Furthermore, while during the last decade Ecuador has achieved near 100% blood screening coverage for T. cruzi infection, the 15 participating blood banks regularly report seropositive blood donors to the External Performance Evaluation of Serological Screening Program administered by the Pontifical Catholic University of Ecuador.
The vector control program was effectively started in 2004. However, due to limited human and financial resources, there have been important variations in the geographic coverage of the surveillance and control activities from year to year . Importantly, a total of 12 provinces have not been included in these activities, representing an area larger than the covered provinces. Therefore, the available data do not correspond to a systematic national coverage, and thus still present an incomplete picture of the current transmission of Chagas disease in Ecuador. In the 11 provinces in which surveillance and control activities have been performed, house infestation by triatomines is still observed in many regions [7,13]. While vector control activities have had a significant effect and allowed reducing the infestation level, particularly in coastal Ecuador, these need to be sustained to avoid reinfestation and provide long-term effects. Also, while insecticide spraying may be effective against Triatoma dimidiata, a possibly domiciliated species which is poised for elimination in Ecuador, alternative control strategies may be needed against intrusive triatomine species such as Rhodnius ecuadoriensis or Panstrongylus howardi or for occasional exposure outside of homes [14–19]. Moreover, no formal vector control intervention has been implemented in the Amazon region, where nearly half of the cases of the country seem to originate , and active transmission still occurs through triatomine species including Rhodnius robustus and R. pictipes [8,9]. Especially in the Amazon, human activities (deforestation, urbanization) disturb the natural balance between the vectors, their wild hosts and the parasite, favoring the emergence of new transmission cycles in which humans may be included [8,9,11,20].
An accurate description of the situation of Chagas disease in Ecuador should mention that access to diagnosis throughout the country is limited and case detection during the last two decades has been sporadic and geographically restricted. Indeed, only one laboratory in the whole country, at the Instituto Nacional de Investigación en Salud Pública (INSPI), performs official confirmation of anti-T. cruzi seropositivity and releases Nifurtimox for the treament of patients. In fact, we believe that lack of awareness by health care personnel in areas with active vectorial transmission, combined with lack of diagnostic capacity elsewhere in the country, have resulted in a gross under reporting of cases in Ecuador.
Taken together, these data and studies highlight that Chagas disease is all but controlled in Ecuador, contrary to what is stated by Cartelle Gestal et al. While it is clear that disease surveillance and vector control activities from the Ministry of Public Health have improved over the years, these need to (i) reach national coverage to ensure the inclusion of all endemic provinces, and (ii) be sustained to ensure that what has been achieved can result in long-term control of the disease. These represent a clear challenge at a time when the Ministry of Public Health is undergoing major structural reorganization and many of its activities are being decentralized or interrupted. Indeed, there is a decrease in reported human cases and in vector controls activities observed in the past two years in Ecuador , which may reflect the interruption of the National Chagas Program and the Servicio Nacional de Control y Vigilancia de Enfermedades Transmitidas por Vectores Artrópodos (SNEM) in late 2015. Their actions have not been replaced yet, so that there is currently no Chagas vector control program in the country. This can strongly jeopardize the results achieved so far and may be a lost opportunity to eliminate vectorial transmission with domiciliated vectors in some regions of Ecuador.
Finally, as in many other countries in Latin America, current activities for Chagas disease control in Ecuador still need to improve treatment access and care for Chagas disease patients [21–23] as well as to better understand the importance of congenital transmission in the epidemiology of the disease [9,24]. Thus, control of Chagas disease in the country will only be reached if the programs from the Ministry of Public Health are strengthened and expanded. The National Chagas disease control programs in other Latin America countries such as Brazil, Argentina, or Colombia (among others) can provide key examples of successful strategies for Chagas disease surveillance and control, as well as of the challenges encountered for their implementation. Additionally, research needs to be performed to further expand our understanding of triatomine infestation and T. cruzi transmission cycles in the different specific endemic areas, to help further tailor surveillance and interventions. More than claiming that Chagas disease is controlled, we need to promote further political commitment to sustain current achievements in Chagas disease surveillance and control in Ecuador and to ensure that the goals of the London declaration on neglected tropical diseases  are met in the near future.
Conceived and designed the experiments: ED CH LM MJG AGG JAC HMA SFB EW. Analyzed the data: ED CH LM MJG AGG JAC HMA SFB EW. Wrote the paper: ED CH LM MJG AGG JAC HMA SFB EW.
- 1. Cartelle Gestal M, Holban AM, Escalante S, Cevallos M (2015) Epidemiology of Tropical Neglected Diseases in Ecuador in the Last 20 Years. PLoS One 10: e0138311. pmid:26394405
- 2. Ministerio de Salud Pública (2013) Manual de procedimientos del subsistema alerta acción SIVE–ALERTA. Dirección Nacional de Vigilancia Epidemiológica. Segunda edición. Quito: MSP. pp. 220.
- 3. Abad-Franch F, Aguilar HM (2003) Control de la enfermedad de Chagas en el Ecuador. OPS/OMS-Ministerio de Salud Pública del Ecuador. 70pp.
- 4. Grijalva MJ, Chiriboga R, Racines JR, Escalante L, Rowland EC (1997) Short report: screening for Trypanosoma cruzi in the blood supply by the Red Cross blood bank in Quito, Ecuador. Am J Trop Med Hyg 57: 740–741. pmid:9430538
- 5. Grijalva MJ, Escalante L, Paredes RA, Costales JA, Padilla A, Rowland EC, et al. (2003) Seroprevalence and risk factors for Trypanosoma cruzi infection in the Amazon region of Ecuador. Am J Trop Med Hyg 69: 380–385. pmid:14640497
- 6. WHO (2015) Chagas disease in Latin America: an epidemiological update based on 2010 estimates. Wkly Epidemiol Rec 90: 33–43. pmid:25671846
- 7. Quinde-Calderon L, Rios-Quituizaca P, Solorzano L, Dumonteil E (2016) Ten years (2004–2014) of Chagas disease surveillance and vector control in Ecuador: successes and challenges. Trop Med Int Health 21(1): 84–92. pmid:26458237
- 8. Amunárriz M, Quito S, Tanzado V, López M (2010) Seroprevalencia de la enfermedad de Chagas en el cantón Aguarico, Amazonía ecuatoriana. Rev Panam Salud Publica 28: 25–29. pmid:20857017
- 9. Carrera Vargas C, Orlando Narváez A, Muzzio Aroca J, Shiguango G, Martini Robles L, Herrera C, et al. (2015) Seroprevalence of Trypanosoma cruzi infection in school children and in pregnant women from an Amazonian region in Orellana province, Ecuador. Am J Trop Med Hyg 93: 774–778. pmid:26283751
- 10. Black CL, Ocana-Mayorga S, Riner DK, Costales JA, Lascano MS, Arcos-Teran L, et al. (2009) Seroprevalence of Trypanosoma cruzi in rural Ecuador and clustering of seropositivity within households. Am J Trop Med Hyg 81: 1035–1040. pmid:19996434
- 11. Guevara AG, Atherton RD, Wauters MA, Vicuna Y, Nelson M, Prado J, et al. (2013) Seroepidemiological study of chagas disease in the southern Amazon region of Ecuador. Trop Med Health 41: 21–25. pmid:23532947
- 12. Guevara A, Moreira J, Criollo H, Vivero S, Racines M, Cevallos V, et al. (2014) First description of Trypanosoma cruzi human infection in Esmeraldas province, Ecuador. Parasit Vectors 7: 358. pmid:25095872
- 13. Grijalva MJ, Villacis AG, Ocana-Mayorga S, Yumiseva CA, Moncayo AL, Baus EG, et al. (2015) Comprehensive survey of domiciliary triatomine species capable of transmitting Chagas disease in southern Ecuador. PLoS Negl Trop Dis 9: e0004142. pmid:26441260
- 14. Grijalva MJ, Villacis AG, Ocana-Mayorga S, Yumiseva CA, Baus EG (2011) Limitations of selective deltamethrin application for triatomine control in central coastal Ecuador. Parasit Vectors 4: 20. pmid:21332985
- 15. Nieto-Sanchez C, Baus EG, Guerrero D, Grijalva MJ (2015) Positive deviance study to inform a Chagas disease control program in southern Ecuador. Mem Inst Oswaldo Cruz: 0.
- 16. Villacis AG, Ocana-Mayorga S, Lascano MS, Yumiseva CA, Baus EG, Grijalva MJ (2015) Abundance, natural infection with trypanosomes, and food source of an endemic species of triatomine, Panstrongylus howardi (Neiva 1911), on the Ecuadorian Central Coast. Am J Trop Med Hyg 92: 187–192. pmid:25385867
- 17. Black CL, Ocana S, Riner D, Costales JA, Lascano MS, Davila S, et al. (2007) Household risk factors for Trypanosoma cruzi seropositivity in two geographic regions of Ecuador. J Parasitol 93: 12–16. pmid:17436937
- 18. Waleckx E, Gourbière S, Dumonteil E (2015) Intrusive triatomines and the challenge of adapting vector control practices. Mem Inst Oswaldo Cruz 110: 324–338. pmid:25993504
- 19. Buitrago NL, Bosseno MF, Waleckx E, Bremond P, Vidaurre P, Zoveda F, et al. (2013) Risk of transmission of Trypanosoma cruzi by wild Triatoma infestans (Hemiptera: Reduviidae) in Bolivia supported by the detection of human blood meals. Infect Genet Evol 19: 141–144. pmid:23856437
- 20. Aguilar HM, Abad-Franch F, Dias JC, Junqueira AC, Coura JR (2007) Chagas disease in the Amazon region. Mem Inst Oswaldo Cruz 102 Suppl 1: 47–56. pmid:17891274
- 21. Manne JM, Snively CS, Ramsey JM, Salgado MO, Barnighausen T, Reich MR (2013) Barriers to treatment access for Chagas disease in Mexico. PLoS Negl Trop Dis 7: e2488. pmid:24147169
- 22. Forsyth C (2015) Controlled but not cured: Structural processes and explanatory models of Chagas disease in tropical Bolivia. Soc Sci Med 145: 7–16. pmid:26432176
- 23. Villa L, Morote S, Bernal O, Bulla D, Albajar-Vinas P (2007) Access to diagnosis and treatment of Chagas disease/infection in endemic and non-endemic countries in the XXI century. Mem Inst Oswaldo Cruz 102 Suppl 1: 87–94. pmid:17713680
- 24. Costales JA, Sanchez-Gomez A, Silva-Aycaguer LC, Cevallos W, Tamayo S, Yumiseva CA, et al. (2015) A national survey to determine prevalence of Trypanosoma cruzi infection among pregnant women in Ecuador. Am J Trop Med Hyg 92: 807–810. pmid:25667052
- 25. Tarleton RL, Gurtler RE, Urbina JA, Ramsey J, Viotti R (2014) Chagas disease and the London declaration on neglected tropical diseases. PLoS Negl Trop Dis 8: e3219. pmid:25299701