Health officials detected a case of the parasitic screwworm, known as gusano barrenador, in a domestic dog in Mexico City on April 26, 2026 [2].
The discovery marks the first confirmed instance of the parasite within the capital city. While the case is currently isolated, the presence of the parasite in a high-density urban area increases the need for vigilant veterinary monitoring to prevent a wider outbreak among livestock and pets.
The infected animal, a 12-year-old Doberman [1], was located in the Topilejo area of the Tlalpan borough [3, 4]. SENASICA, the National Service for Agri-Food Health, Safety and Quality, worked with local health authorities to identify the parasite.
Officials said the case is being treated as an isolated incident. There is currently no evidence of wider transmission among other animals or humans in the area [5, 2]. The parasite, a bovine gastrointestinal nematode, typically affects the skin and tissues of mammals.
While this is the first case reported in Mexico City, the parasite has a broader presence across the country. Reports indicate that Mexico has more than 400 active cases of screwworm in dogs nationwide [6].
SENASICA and local authorities continue to monitor the situation in Tlalpan to ensure the infection does not spread to other domestic animals, or local livestock. Health officials said the current risk to the general public remains low.
“The discovery marks the first confirmed instance of the parasite within the capital city.”
The arrival of screwworms in Mexico City represents a geographic expansion of a parasite that primarily threatens the agricultural economy and animal welfare. Because the parasite can affect a wide range of mammals, its presence in an urban center like Tlalpan necessitates stricter biosafety controls to prevent the infection from jumping from domestic pets to commercial livestock, which could lead to significant economic losses for the region's farming sector.
