Transmission, Treatment, and Prevention

Transmission

            As previously stated, Chagas disease is a vector born illness.  The primary form of transmission is through triatomine insects, also knows as ‘kissing bugs’ because they bite the face of victims, or knows as ‘assassin bugs’ because they attack while the victim is sleeping.  These bugs are blood-sucking insects that are capable of carrying the pathogenic parasite, T. cruzi.  When one of   The feces either enters the host’s body through the bite wound, or later through the conjunctiva when the host accidently rubs the infectious feces off their face and into their eye (CDC, 2013).  This is how the parasite is introduced into a new host.  The same parasite-containing insect may then go and infect more hosts, or an uninfected insect may contract the parasite my biting another host and ingesting infected blood, starting the chain of infection.

these insects bites a victim and sucks their blood, they also leave behind feces containing the pathogenic parasite.

            Although vectors are the primary form of transmission, the parasites can be spread in several other ways.  For example, because the parasites multiply in the blood during the acute phase, any contact with the infected blood can be infectious.  This was a particular problem during blood transfusions or organ transplants before screening for the disease began in 2007 (Kirchhoff, 2014).  Passage of the disease can also occur from mother to infant during childbirth.

Treatment/Prevention

            Anyone can get Chagas disease, but prevalence is highest to parts of Central and South America where the triatomine insects live.  Those living in rural areas of tropical endemic countries are at the highest risk.  People in these locations often also have poor living conditions.  Mud walls and thatched roofs give the triatomine insects places to live where they can easily bite and infect new hosts (WHO, 2015).

            If the presence of T. cruzi is detected shortly after infection, treatment with antiparasitic medication can be effective.  Benznidazole and nifurtimox have been shown to be almost 100% effective in curing the disease in the acute phase (Kirchhoff, 2014).  If the disease progresses into the chronic phase however, treatment becomes more difficult as time goes on.  These medications can still be taken to prevent the progression of the disease and lessen the probability of life-threatening symptoms developing later in life, but the parasites will likely never be completely eradicated.

            Although Chagas disease can be difficult to detect and treat, great efforts have been made to reduce its prevalence and spread in endemic countries.  The main focus has been on vector control.  By spraying insecticides near homes and improving housing conditions, the triatomine insects can no longer live near potential human hosts.  People in these rural endemic areas have also been educated to look out for the triatomine insects and to sleep with bed nets to prevent potentially infectious bites.  Finally, spread of the disease from blood transfusions and organ transplants has been curbed by implementation of screening processes (WHO, 2015).

            There is no doubt that these preventative measures have been effective.  According to a recent epidemiological study, the implementation of a multi-country coordinated prevention program in South America has led to a 70% reduction in Chagas disease incidence (Moncayo & Silveira, 2009). 

From Moncayo & Silveira, 2009 

Although preventative measures are effective, the lack of a treatment for the disease is worrisome.  It could be argued that because the main populations at risk for the disease are poor populations, drug companies have little incentive to develop new, expensive treatments that can cure the chronic form of the disease.  While the WHO and individual countries have done well to educate the public and implement prevention programs, it may also be up to them to do the research and development necessary to find a cure.  Research shows that the prevention program in Brazil saves $17 in reduced healthcare and disability costs for every dollar spent on prevention (Moncayo & Silveira, 2009).  This money saved should be reinvested in research and development to help those that are actually dying from the disease.

References:

American Trypanosomiasis (also known as Chagas Disease). (2013). Centers for Disease Control and Prevention.  Retrieved June 18, 2015, from http://www.cdc.gov/parasites/chagas/.

Chagas disease (American trypanosomiasis). (2015). World Health     Organization. Retrieved June 18, 2015, from http://www.who.int/mediacentre/factsheets/fs340/en/.

Kirchhoff, L. (2014). Chagas Disease (American Trypanosomiasis).  Medscape. Retrieved June 18, 2015, from http://emedicine.medscape.com/article/214581-overview.

Moncayo, Á, & Silveira, A. (2009). Current epidemiological trends for Chagas disease in Latin America and future challenges in epidemiology, surveillance and health policy. Memórias Do Instituto Oswaldo Cruz, 17-30. doi:10.1590/S0074-02762009000900005