Chagas Disease Surveillance Activities -- Seven States, 2017

In This Article

Discussion

One goal of public health surveillance for Chagas disease in the United States is to identify local vectorborne transmission and inform strategies to prevent human infection. In Latin America, the risk for infection is high because triatomines infest poorly built housing structures, and peridomestic reservoirs are abundant. The risk for autochthonous transmission in the United States is considered low because of better housing conditions and a lack of transmission associated with domestic reservoirs, such as dogs, and human Chagas cases.^[1,6] With a low risk for local transmission and infrequently reported cases of acute infection, there are fewer opportunities for public health response.^[1]

With an estimated 63–315 congenital T. cruzi infections occurring annually in the United States,^[7] focused surveillance efforts might be beneficial to identify congenital cases. Timely recognition of infection and treatment will prevent disease development in infected infants and reduce the risk for further transmission.^[7] However, surveillance for congenital Chagas disease is challenging in the absence of routine prenatal or newborn screening. More research is needed to better define groups at risk for transmitting congenitally and to understand how to implement effective screening programs.^[1] These states investigate reported cases for possible congenital transmission, but there are no separate surveillance efforts focused solely on congenital transmission.

Awareness of Chagas disease as a public health problem in the United States increased after the introduction of blood donor screening for Chagas disease in 2007.^[8] As of December 2017, at least 2,300 infected blood donors had been reported by blood banks across the United States.^[9] Blood donor screening facilitates recognition and treatment of chronically infected patients and serves as an important source of reported cases for surveillance. However, the rate (of positivity) derived from screening of donors underestimates the underlying prevalence of infection in the United States because of the relatively low rates of blood donation among foreign-born Latinos, who are more likely to be infected than are non-Hispanic whites and African Americans.^[10]

The findings in this report are subject to at least one limitation. The data used for this report might have been subject to recall bias because of the time between surveillance implementation activities in each state and study interview.

If resources are available, surveillance for Chagas disease might be important to conduct in states with large populations at risk, including frequent travelers from countries where the disease is endemic and states at risk for local autochthonous transmission (e.g. have infected mammalian reservoirs and appropriate triatomine vectors), to delineate the actual prevalence of disease. Surveillance efforts can also help to increase awareness among providers, identify unmet health care needs for patients, and assist in linking patients with Chagas disease to treatment to help prevent cardiac and gastrointestinal complications. In addition, although the risk for transmission from mother to child is low in the United States, monitoring for congenital Chagas disease might be considered in states with communities at risk.

Acknowledgment
Gary Balsamo, Louisiana Department of Health.

Table 1. Summary of state surveillance for Chagas disease, including year each state began reporting and primary and secondary reasons for initiating surveillance — Chagas disease surveillance activities, seven states,* 2017
State	Year reporting began	Primary objectives for Chagas disease surveillance	Reasons for initiating Chagas disease surveillance
Arizona	2008	Identify source of infection; monitor acute and chronic disease burden	Presence of T. cruzi-positive triatomines in the state
Arkansas	2013	Identify source of infection; monitor acute and chronic disease burden	Understand the potential burden of locally acquired, congenital, and imported cases; create awareness among physicians working with populations at risk
Louisiana	2013	Identify source of infection; monitor incident cases	Monitor incident cases; assess risk factors for local autochthonous transmission
Mississippi	2010	Identify source of infection; monitor acute and chronic disease burden	Determine whether cases identified by blood banks are caused by local autochthonous transmission; monitor extent of Chagas disease testing occurring at laboratories throughout the state
Tennessee	2010	Identify source of infection; monitor acute and chronic disease burden	Identification of T. cruzi-infected triatomines and nonhuman hosts during a serosurvey
Texas	2013	Identify source of infection; monitor acute and chronic disease burden	Monitor incident cases; assess risk factors for local autochthonous transmission; increase awareness of physicians working with populations at risk
Massachusetts	2008	Monitor chronic disease phase burden	Ensure that blood donors identified through screening are referred for appropriate care