Health officials in Maine confirmed Friday that three people in the Portland area have been diagnosed with active tuberculosis (TB), raising concerns over the world’s deadliest infectious disease.

According to the Maine Center for Disease Control and Prevention, the cases are not genetically linked, indicating that the patients were infected from different sources rather than through direct transmission.

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Health Officials Sound Alarm

The Maine CDC said investigators are now working to identify and screen anyone who may have been in close contact with the three individuals.

TB is caused by the bacterium Mycobacterium tuberculosis, which primarily attacks the lungs but can also damage the kidneys, spine, and brain. If untreated, the disease can lead to respiratory failure and multi-organ damage.

Symptoms typically include:

• A persistent cough (sometimes producing blood or mucus)

• Chest pain

• Fever

• Fatigue and weight loss

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A Global Killer

Tuberculosis is considered the world’s deadliest infectious disease, killing an estimated 1.25 million people each year, according to the World Health Organization. The majority of deaths occur in developing countries, but the illness remains a threat worldwide.

In the United States, 565 people died from TB in 2022, the most recent year for which national data is available.

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Rising Cases in Maine

While officials stressed there is currently no outbreak in the state, cases of TB have been gradually increasing in Maine. Through the end of July 2025, the state had already reported 28 confirmed cases.

“The three active cases in Maine are not genetically linked, meaning they were not transmitted from one person to another,” said Lindsay Hammes, spokesperson for the Maine CDC.

Health officials continue to monitor the situation closely while urging residents to be aware of symptoms and seek medical care if they believe they may have been exposed.