Coura et al. 2007

Talk of the Unknown- Chagas Disease: The Silent Killer

Chagas disease(CD) is a parasitic disease caused by Trypanosoma cruzi mainly transmitted by vectors like triatomines (ex. kissing bugs) ^13.  This disease is endemic to Latin America, affecting 8-10 million people with an average of 41,200 new cases every year^7. However, the disease now has spread worldwide, affecting 300000-400000 people annually in non-endemic countries^5. This is because, many people from endemic regions migrate to non-endemic countries and some of them unknowingly have CD. To add to this, there are over 150 possible vectors all over the world and this disease has no functional vaccine. ^13. Therefore, a minor population carrying CD could easily spread the disease to a completely new population. 

CD presents itself in two stages- acute and chronic. The acute stage appears immediately and displays minor symptoms like fever and rashes lasting from a week to a month. However, if undiagnosed, this could lead to the chronic stage, which presents itself mostly after the age of 35^13. Therefore, CD is a prime example of pathogen-host interaction falling under the selection shadow category. This is specifically due to the chronic phase striking after 35, when an individual has usually passed sexual prime, thereby having lower selection pressures^6. The treatment with benznidazole is only affective when treated just after the onset of acute stage^7. Hence, it is necessary to understand the vector-pathogen-host relationship, study the organism’s evolutionary pattern of pathogenesis to predict the occurrence of CD in a country and on a larger scale, develop effective drugs for acute and chronic phases of the disease.

This would be done in three phases. Firstly, to be able to predict the occurrence of this disease in a country, it is important to collect data about possible vectors and number of affected individuals. Also, it is important to understand human emigration patterns from endemic regions and correlate it with data obtained from vectors. Secondly, using this data, we would observe individuals that stand as exceptions in their individual age groups from different countries and identify as to why, CD is less/ more prevalent in this age group in a country. This would help screen for mutations in the genome which if not mutated, would have usually prevented the occurrence of the disease in that age group. Using all the data obtained, it would be possible to formulate a medication for this disease, and prevent a possible epidemic.

References:

  1. Schmunis, Gabriel A. (2007). Epidemiology of Chagas disease in non endemic countries: the role of international migration. Memórias do Instituto Oswaldo Cruz, 102(Suppl. 1), 75-86. Epub August 31, 2007.https://dx.doi.org/10.1590/S0074-02762007005000093
  2. Coura, José Rodrigues. (2007). Chagas disease: what is known and what is needed – A background article. Memórias do Instituto Oswaldo Cruz, 102(Suppl. 1), 113-122. Epub November 30, 2007.https://dx.doi.org/10.1590/S0074-02762007000900018
  3. Coura, J. R. & Dias, J. C. P. Mem. Inst. Oswaldo Cruz 104 (suppl. 1), 31–40 (2009).
  4. Coura JR, Anunziato N, Willcox HPF 1983. Morbidade da doença de Chagas. I Estudo de casos procedentes de vários estados do Brasil, observados no Rio de Janeiro. Mem Inst Oswaldo Cruz 78: 362-372.
  5. Louis V Kirchhoff (17 December 2010). “Chagas Disease (American Trypanosomiasis)”. eMedicine. Retrieved 12 May 2010.
  6. Fabian, Daniel; Flatt, Thomas (2011). “The Evolution of Aging”. Scitable. Nature Publishing Group. Retrieved May 20, 2014.
  7. Rassi A, Rassi A, Marin-Neto JA (April 2010). “Chagas disease”. Lancet. 375 (9723): 1388–402. doi:10.1016/S0140-6736(10)60061-X.
  8. Rassi A Jr, Rassi A, Marcondes de Rezende J (June 2012). “American trypanosomiasis (Chagas disease)”. Infectious disease clinics of North America. 26 (2): 275–91. doi:10.1016/j.idc.2012.03.002.
  9. “Chagas disease (American trypanosomiasis) Fact sheet N°340”. World Health Organization. March 2013. Retrieved 23 February 2014.
  10. A killer that preys on the poor: Chagas disease” (pdf). Médecins Sans Frontières: Activity Report 2003/2004. Retrieved 29 August 2008.
  11. Bruce Y Lee, Kristina M Bacon, Maria Elena Bottazzi, Peter J Hotez (April 2013). “Global economic burden of Chagas disease: a computational simulation model”. The Lancet infectious diseases. 13 (4): 342–348. doi:10.1016/S1473-3099(13)70002-1.
  12. Garcia S, Ramos CO, Senra JF (April 2005). “Treatment with Benznidazole during the Chronic Phase of Experimental Chagas’ Disease Decreases Cardiac Alterations”. Antimicrob Agents Chemother. 49 (4): 1521–8. doi:10.1128/AAC.49.4.1521-1528.2005.
  13. José Rodrigues Coura & Pedro Albajar Viñas  (June 2010). “Chagas disease: a new worldwide challenge” . Nature. 465, S6-S7.  doi:10.1038/nature09221.
  14. Laia Ventura-Garcia , Maria Roura, Christopher Pell, Elisabeth Posada, Joaquim Gascón, Edelweis Aldasoro, Jose Muñoz, Robert Pool (2013). “Socio-Cultural Aspects of Chagas Disease: A Systematic Review of Qualitative Research”. PLOS. http://dx.doi.org/10.1371/journal.pntd.0002410

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