Two NICU clusters of a rare mold infection struck extremely preterm newborns, CDC reports

Two separate neonatal intensive care units, a year and several states apart, each detected a small cluster of one of the most feared infections in newborn medicine — and in both, investigators came away without a definitive source. A report published 5 November in the CDC's Morbidity and Mortality Weekly Report describes five cases of cutaneous aspergillosis among extremely preterm infants in Michigan and New York during 2023–2024, a window into how fragile the youngest patients are to environmental molds that are harmless to almost everyone else [s1].

Cutaneous aspergillosis is a rare, life-threatening fungal infection caused by Aspergillus species, a group of ubiquitous environmental molds [s1]. Extremely preterm neonates — those born before 28 weeks of gestation — are at heightened risk because of their immature immune defences, underdeveloped skin barriers and frequent exposure to invasive medical devices [s1]. Previous health care–associated mold clusters have been linked to construction, contaminated textiles, contaminated equipment and lapses in infection control [s1].

The Michigan cluster

In October 2023, the Michigan Department of Health and Human Services was notified of two patients with cutaneous aspergillosis in a level IV NICU [s1]. The first, an extremely preterm neonate at 24 weeks' gestational age, developed skin lesions at multiple sites during the first week of life; cultures and biopsy specimens grew Aspergillus fumigatus, confirmed by PCR and genetic sequencing [s1]. About two weeks later, a second A. fumigatus case was detected in another neonate, also at 24 weeks and also in the first week of life, from a lesion on the trunk [s1]. Both infants received the antifungal amphotericin B; the first died in the second week of life, a death attributed in part to aspergillosis, alongside Pseudomonas infection and extreme prematurity [s1].

The Michigan investigation included on-site observations, staff interviews and environmental sampling, and one air sample collected near a corridor used for linen transport grew A. fumigatus — the closest thing to a lead in either outbreak [s1]. In response, the facility converted negative-pressure areas in the shared nursery to positive pressure to reduce airborne spore transmission, repaired plumbing leaks, carpeting and flooring, and designated a separate loading dock for clean linens and supplies [s1].

The New York cluster

During July–September 2024, the New York State Department of Health was notified of three cases in a separate level IV NICU [s1]. The first, a neonate at 24–25 weeks on invasive mechanical ventilation, had an open lesion on the back in the first week of life; culture grew A. fumigatus [s1]. A month later a second neonate, also 24–25 weeks, developed an excoriated lesion, and in September a third, at 24 weeks, developed raised lesions on the back [s1]. The second and third isolates, initially reported as non-fumigatus Aspergillus species, were reclassified by sequencing as Aspergillus quadrilineatus, and whole-genome sequencing suggested the two were closely related [s1]. The three patients were treated with micafungin, with voriconazole plus amphotericin B, and with amphotericin B, respectively; all three survived [s1].

New York's facility found no specific areas of concern and no recent nearby construction, and did not conduct environmental testing [s1]. Its mitigation leaned heavily on linens and barriers: additional linen-dryness checks, replacing some laundered linens with sterile towels, disposable positioning devices, sterile gloves during the first four days of a neonate's care, chlorhexidine-impregnated surgical scrubs for staff and visitors, a review of disinfectants, inspection of the air-handling system in linen-storage areas, and proactive replacement of high-efficiency particulate air filters [s1]. As of 1 September 2026, no additional cases had been identified in either NICU [s1].

Why the clusters matter despite no smoking gun

Neither investigation pinned down where the mold came from, and the report is candid about why that is common rather than exceptional [s1]. Because environmental molds are everywhere and health care exposures can occur through many pathways, environmental sampling may be of limited value unless it is guided by a specific epidemiologic hypothesis [s1]. What both responses show instead is the value of early recognition: in each NICU, spotting the first case triggered enhanced surveillance and a multidisciplinary review bringing together clinicians, infection preventionists, facility engineers and public health staff, and mitigation proceeded even without a confirmed source [s1].

The report's practical message is for the bedside. Clinicians should consider cutaneous aspergillosis in extremely preterm neonates who develop suspicious skin lesions such as areas of redness or ulceration, because early recognition and coordinated assessment can guide mitigation, improve outcomes and prevent further cases [s1]. With five cases and one death across two units, this is not a large outbreak — but in a population this vulnerable, the threshold for taking a skin lesion seriously is exactly what the clusters were built to illustrate [s1].

This article is informational and is not medical advice.