Pharaoh Ants, A Serious Hospital Pest

Modern hospitals in developed countries have amazing patient care technology at their disposal. Yet they may still be afflicted by one of the oldest scourges of the human race: dangerous insects. A species called the Pharaoh ant is especially well adapted to hospital environments and is notoriously difficult to eradicate.

Pharaoh Ant Habits

Pharaoh ants are tiny insects, with adult workers measuring 1.5 to 2.0 mm in length. These reddish-brown ants have no stingers. They are commonly called “sugar ants,” although they seek both sugar and protein food sources.

Pharaoh ants breed continuously in warm, humid climates, and are a common pest in buildings. A typical colony has many queens, each of which can start a new colony. They typically nest in walls and crevices, but in hospital environments, nests have been found in more obscure locations: in linens, between sheets of paper, in incubators for newborns, and even in unopened packages of IV tubing.

These ants forage over large areas and may be found anywhere in a building, regardless of the location of the nest. Common hospital solutions attract Pharaoh ants, including liquid diets for patients, dextrose IV solution, and even plain saline solution.

Problems Caused By Pharaoh Ants

Pharaoh ants cause two main problems in hospitals: they sometimes feed directly on patients, and they are a significant vector of disease.

Patients with open wounds, especially burn patients, are vulnerable to Pharaoh ants, which have been known to feed on wounds and wound secretion. They are small enough to fit through the holes in a gauze bandage. Pharaoh ants have also been found feeding on the skin of premature infants.

Pharaoh ants are also implicated as a vector in the spread of nosocomial infections. They are known to carry a plethora of pathogens, including Streptococcus, Staphylococcus, and Clostridium bacteria. They are able to chew their way into sterile packages of hospital equipment and even directly into IV lines, where they can spread contamination.

Controlling Ant Infestations in Hospitals

Because their nests are hard-to-reach places, Pharaoh ants are difficult to control. Direct application of pesticides can act as a repellent without killing the ants. Poisoned bait traps are more effective because workers feed the bait to young in the nest, but this method of control is slow.

Eradication is especially difficult because of the Pharaoh ant’s life habits. Even if most of a nest is killed, a single fertile queen can start a new nest, which can be the starting point for a new building-wide infestation.

Fortunately, there are ways to protect patients in a hospital with a Pharaoh ant infestation, even without the use of toxic chemicals. The adhesive on tape turned sticky side out forms a barrier the ants cannot cross. They are also unable to get past petroleum jelly. These measures require diligence on the part of the hospital staff, but the alternative is to expose patients to a significant danger from these troublesome insects.

References

Burrus, Roxanne G., 2004. “Pharaoh Ant Consumption of Fluids Used in Hospital Environments.” University of Florida.

Lyon, William F., n.d. “Pharaoh Ant.” Ohio State University.

Photo credit: USDA.