Background: Cryptosporidium oocysts and Giardia cysts can be transmitted by the fecal–oral route and
may cause gastrointestinal parasitic zoonoses. These zoonoses are common in rural zones due to the
parasites being harbored in fecally contaminated soil. This study assessed the risk of illness (giardiasis
and cryptosporidiosis) from inhaling and/or ingesting soil and/or airborne dust in Potam, Mexico.
Methods: To assess the risk of infection, Quantitative Microbial Risk Assessment (QMRA) was employed,
with the following steps: (1) hazard identification, (2) hazard exposure, (3) dose–response, and (4) risk
characterization.
Results: Cryptosporidium oocysts and Giardia cysts were observed in 52% and 57%, respectively, of total
soil samples (n = 21), and in 60% and 80%, respectively, of air samples (n = 12). The calculated annual risks
were higher than 9.9 101 for both parasites in both types of sample.
Conclusions: Soil and air inhalation and/or ingestion are important vehicles for these parasites. To our
knowledge, the results obtained in the present study represent the first QMRAs for cryptosporidiosis and
giardiasis due to soil and air inhalation/ingestion in Mexico. In addition, this is the first evidence of the
microbial air quality around these parasites in rural zones.
2014 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.
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