Cockroaches, beg bugs, and flies do not belong in hospitals or other medical facilities. 

But clinicians do encounter them — hitchhiking on patients’ clothes, scurrying across the floor, and, according to a survey of pest control professionals, in operating rooms and even an MRI scanner .

When these critters are found, they can pose clinical dilemmas.

For example, can a patient undergo cataract surgery if they are found to have bed bugs when they arrive for their appointment?

Can cockroaches transmit antibiotic-resistant bacteria between patient rooms?

If drain flies are discovered in a hospital’s sterile core, do all the surgical supplies require reprocessing?

Infection preventionists and physicians who have confronted these questions firsthand have shared their experiences with colleagues to help establish best practices for handling infestations big and small. They also are conducting studies to better understand risks to patients from insects in medical settings.

The Standard for Personal Protective Equipment (PPE)

The presence of bed bugs and the prospect of bringing a bed bug infestation home from work can be distressing.

So much so that infection preventionists often consider the amount of PPE nurses don when entering the room of a patient known to have bed bugs as the standard that should be applied for other risks, such as bacterial infections.

Online, a game of “would you rather” asks nurses to choose between going into a room with Clostridioides difficile vs with bed bugs.

By a substantial margin — in discussions on Reddit, at least — nurses opt to take their chances with the bacteria . A variation in which the choice is between five patients with COVID or one with bed bugs yielded similar results .

“If you say the word ‘bed bug,’ then all of a sudden you have staff in hazmat suits,” said Stephanie Stroever, PhD, MPH, with Texas Tech University Health Sciences Center in Lubbock , Texas.

Previously, Stroever was director of infection prevention at a hospital where drain flies were discovered in the surgical core.

“I’m like, whoa, where did these come from?” she said. “Depending on how you stratify the risk, we could close the whole thing down and re-sterilize everything, or we have to figure out a way to keep moving while also protecting patients. The challenge here was there is really not good evidence on its reach to the patient.”

Stroever described the scenario at the Association for Professionals in Infection Control and Epidemiology conference in 2024. Among attendees, thoughts on how to proceed were split. Some said they would get rid of the flies and keep surgeries on schedule. Others wanted to reprocess all the equipment, which would cost time and money and could disrupt patient care.

For her part, Stroever wanted to reprocess everything. But administrators questioned if that was necessary or realistic. Data on any risks to patients were limited, after all. The equipment was wrapped, which should prevent any contamination from reaching a patient.

Ultimately, items with visible insect-related gunk on them were reprocessed. Other items were not.

Based on the level of interest in this topic at the meeting, Stroever worked with colleagues to conduct a review of what is known about arthropod-related transmission of microbes in hospitals, which they published in January in Antimicrobial Stewardship & Healthcare Epidemiology.

Their review showed bugs in hospitals have been found to carry clinically relevant pathogens, but definite links to patient infections are lacking.

Dearth of US Data

In conducting the review, Stroever was struck by how few papers came from the US, perhaps because healthcare systems worry being associated with bugs could harm a facility’s reputation. “I think that we like to pretend they’re not there,” she said. “They are there, but we’re not publishing about them.”

In addition to the fly outbreak she discovered in Texas, Stroever said she knows of fly outbreaks that have occurred in health facilities in Colorado and on the East Coast.

Of the 73 studies they included in the review, only four attempted to examine the ability of insects to transmit disease.

One study explored the possible contribution of cockroaches to an infection outbreak in an ICU. In an interview during the outbreak, one nurse noted “there had been an occasional cockroach in patient rooms,” the researchers reported. “These were rare and not perceived to be a serious problem.”

A cockroach was caught, and laboratory tests of the insect identified multidrug-resistant Enterobacter cloacae (MRE) and other pathogens. Following pest control measures, “no new patients were found to be colonized with MRE for 3 months.” Later, another cockroach appeared and a new patient was found to be colonized with MRE.

Some investigators have started to look at genetic data to figure out whether and how pathogens spread between insects and healthcare environments.

Stroever and her coauthors recently began working with an entomologist to conduct further research in this area.

“We know that these insects carry antimicrobial-resistant pathogens and we are in a war against antimicrobial resistance right now, so I feel like it is time to address it,” she said.

Inconsistent Protocols

At the annual meeting of the American Society of Cataract and Refractive Surgery in April, Jennifer R. Long, MD, an ophthalmologist with Kaiser Permanente in California, shared her center’s approach to cataract surgery in patients with bed bugs.

Long focused on this issue after two patients arrived for surgery, both of whom were found to have bed bugs, but only one underwent the procedure. The other surgery was canceled because of the pests.

“In both instances, the final decision was made by the surgeon after careful assessment and collaboration with Infection Prevention and operational leadership,” Long said. But the different trajectories showed “existing guidance was insufficient for consistent decision‑making and risk mitigation in a high‑volume surgical setting.”

So they developed a more structured perioperative protocol.

The protocol includes confirming the presence of bed bugs, notifying the pre-op team, moving the case to the end of the surgical block, and alerting pest control to the problem. Patients’ clothes and linens are sealed in bags, and patients clean themselves using bath wipes and dress in a hospital gown and bonnet. During surgery, the patient’s face is isolated with a nonpermeable adhesive drape. After the procedure, patients receive guidance on exterminating bed bugs at home.

For the one patient who followed this protocol, surgery was successfully completed without infection or environmental transmission of bed bugs, Long reported at the meeting.

“Infection prevention strategies must protect patients and staff without unnecessarily restricting access to essential, vision-restoring care,” she said. “Importantly, bed bug infestation should not automatically exclude patients from cataract surgery.”

Finding the Source

Bed bug activity has surged in medical facilities compared with prior decades, according to Robert Teal, technical services manager for Terminix.

Not because hospitals are breeding grounds for them. Rather, hospitals are high-traffic areas, and some of the many people who go in and out of the facility unknowingly bring bed bugs.

The source of flies in hospitals can be trickier to identify.

Sometimes they simply fly through doors left open during construction.

At one hospital, however, flies were being found throughout the building, and their source was unclear. After setting up monitoring traps and stations where staff could report the insects, they ultimately realized the insects were coming up through a crack in a slab under the building.

Insects can multiply exponentially, so any issue should be dealt with promptly, Teal said. And even a single insect stands out in medical settings.

“One fly or one ant, any sort of pest, is magnified,” Teal said. “It could get stuck somewhere where it’s not supposed to go. All it takes is one.”

Long and Stroever reported having no relevant financial conflicts of interest. Teal reported being a Terminix employee.