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2022 Napa Legionnaires’ Disease Outbreak

Posted in Legionella,Legionnaire's disease,Our Blog,Outbreaks & Recalls on February 10, 2024

In a December publication of the Center for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report, a recap and wrap-up of the 2022 Legionnaires’ disease outbreak in Napa was published. Unsurprisingly, data points to a cooling tower as the source of the outbreak that sickened at least 17 people that Summer.

Scope of the Outbreak

One of the first cases of Legionnaires’ disease was identified in an investigation by Napa County Public Health. To be considered part of this outbreak (for investigative purposes), certain criteria was required. Key requirements included having confirmed legionellosis diagnosis based on either urinary antigen test, polymerase chain reaction (PCR) test, or culture and the patient must be someone who lived, worked, or spent time in downtown Napa as well has experiencing illness onset during or after June 2022. If those criteria were met, the illness was considered a “confirmed case.” A “suspected case” included those who had community-acquired pneumonia of unknown origin that was either a hospitalized patient, a resident/worker/or visitor to downtown Napa, or a patient that did not receive specific testing for Legionella ssp (the bacteria responsible for Legionnaires’ disease) during hospitalization.

Of the 17 patients, 14 lived in downtown Napa, two reported vising downtown Napa, and one worked in downtown Napa.

Napa County Public Health identified 17 cases in this outbreak. This included 14 confirmed cases and three suspected cases. All confirmed cases were determined by urinary antigen testing. Most of these cases were severe. All but one patient required hospitalization, with 10 admitted into intensive care units. There were five patients that required intubation and mechanical ventilation. One patient died.

Some of the patients also struggled with diabetes, hypertension, lung disease, heart disease, and smoking. Additionally, two of the patients were co-infected with SARS-CoV-2, the virus responsible for COVID-19.

High Risk Zone Identified

A cluster of patients’ residences (most patients lived in the downtown Napa area) was a key factor of identifying the “high-risk zone” for the outbreak. This zone consisted of a 1-mile radius around the center of the cluster.

Based on the geographical area, patient interviews, and common sources, seven facilities were indicated with nine potential sources in the high-risk zone. Seven cooling towers, a decorative fountain, and a produce mister were investigated.

Two facilities were narrowed down as the likeliest sources, as they were the highest scoring in the risk score analysis.

Cooling Tower Violations Discovered

Upon inspection, several violations were observed. Poor records, lack of routine biocide application with improper distribution methods as well as low or no detectable chlorine at the time of sampling may have been potential contributing factors.

One of the facilities had a clogged pipe in the chemical feed system that was reported about the same time as many of the case exposures occurred.

Genetic Data Points to One Cooling Tower

Public health investigators collected samples from 11 potential sources in an effort to determine the source of the outbreak. Of the 11, seven tested positive for Legionella bacteria.

Both clinical and environmental samples underwent genetic testing to determine if the bacteria were related. Samples from one of the cooling towers were, in fact, a match for the patient samples. Genetic data from other environmental samples showed less in common with clinical samples.

The matching cooling tower sample also happens to be the facility that had the clogged pipe around the time people began reporting illness.

Contaminated Cooling Towers Can Spread Legionella

The puzzling part of the investigation was that no Legionnaires’ disease cases were linked back to occupants of that facility.

But how?

According to reports, “cooling towers can spread Legionella over a wide geographical area, with highest attack rates among persons living within 0.6 miles (1.0 km)” of a contaminated tower. This increases risk to not only those inside the building, but the surrounding area as well. Neighborhoods near large facilities with cooling towers are at increased risk.

Complications of COVID-19 and Co-Infection

Additional complications have been evident in the midst of COVID-19. Similarities between Legionnaires’ disease symptoms and those of COVID-19 pose significant challenges to diagnosis resulting in an increased risk of delayed care.

When a clear diagnosis of certain illnesses such as COVID-19, a physician may not look to further diagnoses. However, treatment for COVID-19 and treatment for legionellosis are quite different.

Specialized antibiotics are required for faster recovery of Legionella infection, though treatment of symptoms and boosting the immune system can be beneficial for both COVID and Legionnaires’ disease.

What is Legionnaire’s Disease?

Legionnaires’ disease is caused by the infection with Legionella bacteria. This can also be called legionellosis. Two types of legionellosis can develop from this bacterial infection – Legionnaires’ disease and Pontiac Fever. This bacterium is naturally occurring in fresh water such as lakes, rivers, and streams. It becomes a problem to humans when the bacteria grow in man-made areas were it can be breathed into the lungs, causing a pneumonia-type illness.

Legionnaires’ disease is associated with pneumonial illness, Pontiac Fever is associated with non-pneumonial symptoms.

Common Sources

The bacteria grow dangerous when it becomes aerosolized and the small droplets containing the harmful bacteria make its way into the lungs. Certain man-made features are common sources for dispersing Legionella bacteria into the air if contaminated.

Common sources include:

  • Showerheads and sink faucets
  • Cooling towers (such as those used in large buildings’ air-cooling systems or industrial processes)
  • Hot tubs
  • Decorative fountains and water features
  • Hot water tanks and heaters
  • Large, complex plumbing systems
  • Plumbing systems under construction, where dead legs are present

Legionnaires’ Disease Symptoms

Legionnaires’ disease is often undiagnosed, as symptoms are similar to other types of pneumonia, sometimes even indistinguishable on a chest x-ray.

Common symptoms include:

  • Cough
  • Shortness of breath
  • Fever
  • Muscle aches
  • Headaches

Other symptoms may include:

  • Diarrhea
  • Nausea
  • Confusion

These symptoms usually begin anywhere from 2 to 14 days after exposure, though in some cases it can take even longer.

Proper diagnosis (requiring laboratory tests) allows health care providers to treat the Legionella infection instead of non-specific pneumonia treatment. Appropriate medication will help the patient make a better, potentially faster, recovery.

Pontiac Fever

Pontiac fever is the milder type of Legionella infection, marked by the absence of pneumonia. Primary symptoms of Pontiac Fever include fever and muscle aches that can begin within a few hours and up to 3 days after being exposed to the Legionella bacteria. Pontiac Fever illness usually resolves in less than a week.

Most people do not know they have Pontiac Fever unless they have other extenuating circumstances. Normally healthy people often recover from Pontiac Fever without medical assistance.

Did You Become Sick After Visiting Napa in 2022?

Becoming sick, especially with such a serious illness, can be quite scary and stressful. Particularly in situations such as Legionnaires’ disease, where infection is preventable with basic and required maintenance. Medical bills, lost time, and other burdens can be a lot to handle.

An experienced Legionnaires’ disease lawyer can help you navigate this process. If you have been injured at the negligence of others, The Lange Law Firm, PLLC can help you determine if you have a case. Reach out by phone to (833) 330-3663 or click here to email for a free consultation.

By: Heather Van Tassell