HHS details New World screwworm response after human case

News brief

flies — Judy Gallagher / Wikimedia Commons

In light of the recent report of a traveler-associated human case of New World screwworm (NWS) infection in Maryland, the first human US case in 50 years, the Centers for Disease Control and Prevention (CDC) and the US Department of Health and Human Services (HHS) reaffirmed their commitment to robust surveillance and trapping strategies targeting the parasitic fly.

Currently, the risk to public health in the United States from this case is very low.

"Currently, the risk to public health in the United States from this case is very low," HHS said in a press release. "In support of CDC's activities and out of an abundance of caution, [the US Department of Agriculture] initiated targeted surveillance for NWS within a 20-mile radius of the affected area, encompassing portions of the District of Columbia, Maryland, and Virginia. To date, all trap results have been negative for NWS."

Last US animal detection in 2017

HHS said the last time NWS was detected in animals or livestock in the United States was in the Florida Keys in 2017. There have been no detections since then.

"We may continue to see traveler-associated cases of NWS," HHS said. Any warm-blooded animal can become infected by a New World screwworm, but human infection is rare.

Central America is experiencing a large uptick of NWS activity. HHS said officials have heightened surveillance of the pest along the Mexico-US border that has been in place since this summer. HHS also said it is building a domestic sterile-fly production and dispersal facility to increase readiness and response efforts.

PAHO warns antibiotic-resistant pertussis is spreading

News brief

Lisa Schnirring

The Pan American Health Organization (PAHO) yesterday urged countries in the Americas region to step up their pertussis (whooping cough) surveillance and vaccination efforts due to rising infections that now include the spread of antibiotic-resistant strains.

child vaccination — *Ran Kyu Park / iStock*

Treatment of Bordetella pertussis infections relies on macrolide antibiotics including azithromycin, clarithromycin, and erythromycin. However, genetic mutations in the bacteria’s 23S rRNA reduces drug effectiveness for treating patients and contacts. Since 2024, antibiotic-resistant pertussis cases have been detected in four Americas countries: Brazil, Mexico, Peru, and the United States.

PAHO said widespread inappropriate use of antibiotics like azithromycin during the COVID-19 pandemic may have contributed to the emergence of resistant pertussis strains.

Urgent action needed to contain resistance

Pilar Ramón-Pardo, MD, PhD, who heads PAHO’s special program on antibiotic resistance, said vaccination, surveillance, and responsible use of antibiotics are critical to prevent pertussis from becoming a serious public health threat again. Scientists shared their concerns during a recent meeting of the Latin American and Caribbean Network for Antimicrobial Resistance Surveillance. “We still have time to contain this issue, but we must act now: increase vaccination coverage, strengthen early detection, and enhance our outbreak response capacity,” she added.

We still have time to contain this issue, but we must act now.

The emergence of resistant strains comes amid a global resurgence of pertussis over the past few years due to declining vaccination rates. Countries in the Americas recorded 4,139 cases in 2023, with the total surging to 43,751 in 2024. In the first 7 months of 2025, countries have already reported 18,595 cases, 128 of them fatal.

During the pandemic, regional coverage of the first and third diphtheria, tetanus, and pertussis (DTP) vaccine in the Americas declined to historic lows and has partially recovered. However, PAHO said the rates remain below the 95% recommended levels, with significant disparities within countries. Alongside childhood vaccination, PAHO recommends immunization for pregnant women, especially during outbreaks, and health workers who have contact with newborns.