A Woman Was Hospitalized With Melioidosis, a Rare Bacterial Infection Caught From Her Tropical Fish Tank

Fish seem like a harmless enough pet: You feed them and clean out their tanks regularly, and that's about it. But one Maryland woman ended up catching a rare and serious tropical disease bacterial disease from her fish tank.

The 56-year-old woman's story was broken down in a case report in the journal Emerging Infectious Diseases. The report details how the woman, who was not publicly identified, was first hospitalized in September 2019 with a fever, cough, and chest pain. She was diagnosed with pneumonia, but further testing showed that she was infected with the bacteria Burkholderia pseudomallei. This bacteria causes a disease called melioidosis that's usually seen only in tropical areas outside the US.

Melioidosis, also known as Whitmore's disease, is an infectious disease that can infect humans or animals, according to the Centers for Disease Control and Prevention (CDC). Melioidosis is most common in tropical climates, and it's usually found in Southeast Asia and northern Australia. B. pseudomallei is usually found in contaminated water and soil. It's often spread when someone inhales contaminated dust or water droplets, drinks contaminated water, eats food that's been in contaminated soil, or comes into direct contact with contaminated soil, especially through cuts or scrapes, the CDC says.

Melioidosis can cause a range of different symptoms depending on the type of infection a person gets, the CDC says. For localized infections, someone might develop pain or swelling, a fever, or an abscess. For a chest infection, they may have a cough, chest pain, high fever, headache, and weight loss. With a bloodstream infection, a patient could develop a fever, headache, respiratory issues, stomach pain, joint pain, and disorientation. If a person has a widespread infection, they may develop a fever, weight loss, stomach or chest pain, muscle or joint pain, headache, seizures, and brain infection.

People who are diagnosed with melioidosis in the US usually have recently traveled to areas where the infection is more common, but the woman had never left the country, the researchers wrote.

The woman started taking an antibiotic called meropenem, and after 11 days, she left the hospital. But three weeks later, she was back again with the same symptoms, even though she was still on antibiotics. She was hospitalized for another week and given a second antibiotic. From start to finish, it took 12 weeks of treatment to clear her infection.

Because melioidosis is so rare and not normally seen in the US, pubic health officials had questions about how the woman, who also had diabetes, became infected. They took samples from in and around her home, including from her two aquariums. One fish tank tested positive for B. pseudomallei, and it was a perfect genetic match to the bacteria that infected the woman.

The woman shared that she had bought the fish tanks, fish, and supplies just two months before she became sick and said that she had put her bare hands and arms into the tank while she cleaned it.

"We urge clinicians in the United States to consider melioidosis in patients who have clinically compatible symptoms and exposure to tropical ornamental fish and freshwater aquariums, particularly if patients are immunocompromised, even though such exposure events might be exceedingly rare," the researchers wrote in the paper.

If you have fish, the CDC recommends taking a few steps to stay safe from diseases they can pass on: Wash your hands before and after cleaning the aquarium and feeding fish, and wear gloves to cover any cuts on your hands while cleaning the aquarium or handling fish.