Mysterious Outbreak of Bilateral Pneumonia in Northern Argentina

Matías A. Loewy

September 19, 2022

UPDATED September 3, 2022: Argentina's Ministry of Health confirmed that the outbreak's etiologic agent is Legionella, likely Legionella pneumophila, although the exact classification has yet to be determined. The bacteria could have originated in the plumbing or in the air conditioning units. To date, there have been 11 confirmed cases and 4 deaths.

BUENOS AIRES, Argentina — Authorities are investigating an outbreak of bilateral pneumonia of unknown origin which, since August 18, has stricken at least eight healthcare workers at a private clinic in the northern city of San Miguel de Tucumán. Of the eight, two — both men — have died: a 68-year-old physician and a 45-year-old nurse. A 70-year-old woman who had been admitted for gallbladder surgery also fell ill and died.

"Most of the patients presented with vomiting, high fever, diarrhea, and body aches. In some patients, the course of the disease was more complex. Two of the initial six patients are still in serious condition and currently on ventilators," Luis Medina Ruiz, MD, the minister of public health of the province of Tucumán, reported during a press conference September 1.

"The infectious diseases community suggests that we consider legionellosis, although the related bacteria species are difficult to culture and costly to identify," noted Miguel Ferré Contreras, MD, executive secretary of the Provincial Health System (SIPROSA). He went on to say that "25 separate causes" have been ruled out.

Legionnaire's disease, one of two forms of legionellosis, is contracted through inhalation of aerosolized water containing Legionella species or through aspiration of water contaminated with such bacteria. There has been no confirmation about the route of transmission involved in the current outbreak. In 2013, the first outbreak in Argentina identified as having these characteristics was among workers and patients at a hospital in Carmen de Areco, a town two hours west of Buenos Aires. Two women, both nurses, died. And cases of nosocomial infection were recorded in 2019 and 2020. Another hypothesis that emerged was that it could be leptospirosis.

As Argentina's Ministry of Health announced in an August 31 press release, the Dr. Carlos Malbrán National Administration of Laboratories and Institutes of Health (ANLIS) — the national reference center for analyzing infectious diseases — had received samples from Tucumán's initial "six cases of pneumonia of unknown origin in order to carry out further diagnostic testing."

"In addition," the press release reported, "national and provincial health authorities are working together on investigating the outbreak, including the following-up of cases, contact tracing, and implementing control measures specific to the facility where the outbreak arose."

At a press conference the following day, Medina Ruiz provided additional details. "Last night and this morning, we got some information from our colleagues at ANLIS Malbrán. So far, all the analyses that came back negative for us — for COVID-19, hantavirus, and some strains of Legionella — are also coming back negative for them. We're continuing to press forward with the research protocol that includes various tests: blood cultures, sputum cultures, urine cultures, and cultures of all viruses and bacteria that are available to us in the province."

"There are hypotheses being put on the table about the etiology," Medina Ruiz added, "although what we have, specifically, are the common origin and the course of the disease."

As for the healthcare workers affected: there is another physician as well as a pharmacy assistant, but the majority are nurses; the youngest is 30, and he has comorbidities. Four are hospitalized, and others are isolating at home.

"This situation that we're living through now has given rise to a feeling of alarm, one that very much brings back memories of what we were living through while in quarantine and throughout the COVID-19 pandemic," psychologist Lucas Haurigot Posse wrote in an op-ed for Tucumán's La Gaceta newspaper. "Things are still so fresh in our minds — everything surrounding the fear of infection, all the uncertainty and the powerlessness that we felt when it came to planning for the future or having an idea of what that future was going to look like."

The international press has also reported on the outbreak. For example, in the United Kingdom, an article in the Daily Mail mentioned "alarming similarities to how COVID began to spread in Wuhan in late 2019." And in its article, the Telegraph quoted Devi Sridhar, DPhil, MPhil, professor of global public health at the University of Edinburgh, United Kingdom. "It's obviously concerning, but we still need key information on transmission and hopefully [on the] underlying cause," he said.

Follow Matías A. Loewy of Medscape Spanish Edition on Twitter @Mloewy.

This article was translated from the Medscape Spanish Edition.

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