Health Officials Address Human Case of Flesh-Eating Parasite

A human case of the flesh-eating New World screwworm has been reported in Maryland, raising concerns about potential outbreaks in the United States. The patient, who had returned from El Salvador, was diagnosed with the condition, as confirmed by the Centers for Disease Control and Prevention (CDC) on August 4, 2023. This incident marks the first case in the U.S. linked to travel from a country currently experiencing an outbreak of the parasite.

Maryland health officials stated that the patient has recovered and noted that there have been no further transmissions to other individuals or animals. According to the CDC, New World screwworm infestations occur when larvae from the screwworm fly invade the living flesh of warm-blooded animals. Female screwworm flies lay between 200 to 300 eggs at a time on open wounds and mucous membranes, leading to severe tissue damage as the larvae feed on living flesh. While infestations in livestock are most common, human cases, described by the CDC as “very painful,” are rare.

Countries in Central America and Mexico have reported recent outbreaks affecting both animals and humans. Despite this case, Andrew G. Nixon, a spokesman for the Department of Health and Human Services (HHS), reassured the public, stating that “the risk to public health in the United States from this introduction is very low.” Over the past fifty years, the U.S. has largely eradicated screwworm populations using a method of breeding and releasing sterile male flies to mate with females.

Understanding the Risks and Precautions

In response to the recent case, U.S. Secretary of Agriculture Brooke L. Rollins announced plans to construct a sterile fly facility in Edinburg, Texas, as part of ongoing efforts to eliminate the pest. The focus remains on preventing the flies from establishing populations within the U.S.

Infectious disease researcher Laurel Bristow from Emory University’s Rollins School of Public Health emphasized that there is no immediate cause for concern regarding further cases in the U.S. She noted that the fly is not currently present in the country and that health officials are monitoring the Maryland patient closely. “You just don’t want the flies to move through the larval stage,” she explained, indicating that the risk of more cases developing is minimal.

Despite the low risk, experts urge caution, particularly in areas where the screwworm is known to be present. Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security, recommends that travelers to regions with known outbreaks should take precautions, such as covering open wounds, avoiding outdoor sleeping, and using insect repellents. “The risk is primarily in areas close to livestock,” he added.

Preventive measures include treating clothing and gear with products containing 0.5% permethrin and sleeping indoors or in screened rooms. Bristow pointed out that while human cases are rare, it is important to be vigilant. The primary concern remains for livestock, particularly within the beef industry, should the screwworm establish a foothold in the U.S.

Signs of Infestation and Treatment

For those concerned about possible infestations, Bristow advised that individuals should seek medical attention if they notice signs of maggots in a wound or if a wound is not healing properly. The CDC specifies that the only treatment for New World screwworm infestations involves the physical removal of larvae from the infested tissue.

As health officials continue to monitor the situation, they stress the importance of awareness and preventive measures. The recent case in Maryland serves as a reminder of the need for vigilance in travel and health practices, particularly in areas with known outbreaks of the New World screwworm.