Investigating a Case of Nosocomial Myiasis

Session Description: Myiasis, the infestation of human tissues by fly larvae, is most often associated with tropical and subtropical climates and exposure to flies that prefer to lay their eggs in animal tissues. Healthcare-acquired myiasis in temperate regions of the United States is rarely reported.
In early July, a patient was found to have “worms” crawling out of his nose and mouth on day eight of his hospitalization in the surgical intensive care unit (ICU). Subsequent analysis by the pathology laboratory revealed that the “worms” were in fact insect larvae. This presentation will describe the investigation we conducted to determine the type of insect larvae that were found, whether or not the infestation may have been acquired in the hospital, the factors that contributed to the occurrence of this case, and subsequent prevention measures that were implemented.
Identification of the larvae to the species level allowed an analysis of the probable date that eggs were deposited (oviposition) in the patient’s oropharynx because the developmental rate of fly larvae is species specific. We determined that the larvae were from a black blowfly Phormia regina, and oviposition most likely occurred on day 4 of hospitalization. No other patients with maggot infestations or intentional maggot therapy were present in the hospital at the time, but there were multiple reports by ICU personnel of what they thought were houseflies on the unit. Environmental investigation revealed there were small gaps in the building adjacent to the ICU that were possible entry points for flying insects. We identified a need for increased coordination and knowledge sharing between facilities management, environmental services, nursing personnel, infection prevention and control, and contract pest control services. We have established a multidisciplinary integrated pest management committee to proactively address risk of vector-borne hospital infections and infestations.

John Townes

Medical Director, Infection Prevention and Control, Oregon Health & Science University

Dr. Townes is a Professor of Medicine in the Division of Infectious Diseases and Medical Director of Infection Prevention and Control at OHSU. He is a graduate of Brown University (1982) and The Johns Hopkins School of Medicine (1990). He completed residency in Internal Medicine at The Johns Hopkins Hospital in 1993 and then served in the US Public Health Service as an Epidemic Intelligence Service (EIS) officer in the Foodborne and Diarrheal Diseases Branch at CDC. He worked with the Emerging Infections Program at the Oregon State Health Department for two years before completing his fellowship in Infectious Diseases at Vanderbilt University in 1998. He joined the faculty at Oregon Health & Science University (OHSU) in 2000 with a primary academic focus on emerging infections and the nexus between clinical medicine and public health. He has been medical director of Infection Prevention and Control at OHSU since 2008.

Maria Whitaker

Infection Preventionist, Infection, Prevention and Control Consulting Services

Maria Whitaker, BS,MT,CIC, is an Independent Infection Prevention and Control Consultant. She worked as a Clinical Microbiologist for 18 years before pursuing her career in Infection Prevention. For the next 22 years, Maria worked as the manager for the Infection Prevention and Control Program in both the acute and long-term care settings at Guthrie Cortland Medical Center in Cortland, New York. Maria is very active in APIC. She has served as President and Chair of the Education Committee for her local Chapter, and has served on several committees at the National level; including Practice Guidance Committee, Communications Committee and is currently a member of the Annual Conference Committee.