Brain-Eating Amoeba Found in Six Artificial Lakes in Mérida; Water Contact Restricted

Mérida, Yucatán — Health authorities have detected the amoeba Naegleria fowleri, commonly known as the “brain-eating amoeba,” in six of nine artificial water bodies tested in Mérida, prompting officials to ban all contact with the water at those sites and launch sanitation work.

The Yucatán Health Services (SSY) said the results come from an expanded surveillance program launched after a 34-year-old man died in September from an infection linked to the amoeba. The man had been in contact with water at the lake in Plaza La Isla.

Where the amoeba was found

Laboratory tests confirmed the microorganism in the lake at Plaza La Isla; the east and main lakes of the Cabo Norte residential complex; the lake at the Centenario Zoo; the lake at Gran Parque La Plancha; and the lake at Parque Ecológico del Poniente.

Tests at three other sites — the central lake at Cabo Norte, the Acuaparque and the lake at Animaya Zoo — found no trace of the amoeba.

In response, health officials ordered physical barriers and warning notices installed to keep people away from the water at the six affected lakes.

Managers of each site have begun sanitation procedures with support from specialists at the Autonomous University of Yucatán (UADY) and the Center for Research and Advanced Studies (Cinvestav).

Parks and zoos stay open

The SSY stressed that the parks, zoos and other facilities containing the lakes will remain open to the public, noting that the water bodies serve mainly an ornamental purpose and are not intended for swimming.

At Animaya Zoo, where no amoeba was detected, catamaran tours continue without direct contact with the water.

Officials explained that Naegleria fowleri occurs naturally in freshwater, particularly when water is warm and stagnant. While it can cause a severe brain infection known as primary amebic meningoencephalitis, infections in humans are extremely rare.

Infection occurs when contaminated water enters through the nose and the amoeba reaches the central nervous system. It does not spread from person to person and cannot be contracted by drinking contaminated water.

The SSY said the 361 people identified as having been in contact with the Plaza La Isla lake completed their health monitoring period on October 4 with no new infections detected.

Expanded surveillance

After the September death, the Yucatán government launched a program to monitor artificial water bodies with the participation of academic institutions and water-management agencies.

An interinstitutional water safety panel — made up of representatives from UADY, Cinvestav, the Dr. Hideyo Noguchi Regional Research Center, the Yucatán Potable Water and Sewerage Board (Japay) and the National Water Commission (Conagua) — is drafting permanent criteria for operating and monitoring these sites.

The SSY said each operator, whether a municipal or federal authority or a private company, will be responsible for carrying out the required sanitation measures.

Restricted water bodies will only return to normal operation once they meet the health authority’s requirements and laboratory results confirm conditions are safe.

Surveillance will continue at other artificial lakes in Mérida, with results released as analyses are completed.

Authorities urged residents to prevent lake and pond water from entering the nose, regardless of whether amoeba tests are positive. They also advised anyone who has had contact with these water bodies and develops symptoms such as fever, severe headache, nausea, vomiting or neck stiffness to seek immediate medical attention.

For health guidance, the agency provided the phone number 999 947 2198.