Human Myiasis Cases confirmed in Chiapas, Mexico

Teh Mexican Ministry of Health (Ssa) has recently reported two confirmed cases of human myiasis, a parasitic infestation caused by fly larvae, specifically linked to the BARENDER WORT of cattle, in the state of Chiapas.The affected individuals include a 77-year-old woman from Acacoyagua and a 50-year-old man from Tuzantán. This growth raises concerns about the potential for increased human infections, especially in rural communities.

Understanding the Threat: Human Myiasis and Cattle Infestation

Human myiasis is more prevalent among individuals residing in rural areas, particularly during seasons when the density of Cochliomyia hominivorax flies is high. These flies, commonly known as screwworms, thrive in warm-blooded animals, making livestock a primary breeding ground. The Ssa has warned that a surge in animal myiasis cases can directly contribute to a rise in human infections.

“Las Human myiasis They are more frequent among rural residents, especially in areas and seasons with high density of flies C. hominivorax. The reproduction of these flies is closely linked to the presence of hot blood animals. Therefore, an increase in cases of animal myiasis can lead to an increase in human cases.”

Mexican Ministry of Health (Ssa) Epidemiological Bulletin

this highlights the critical need for proactive measures to control screwworm populations in livestock and prevent further spread to humans.According to the World Health Organization (WHO), myiasis can affect various parts of the body, leading to severe tissue damage and potential complications if left untreated.

Alarming Rise in Animal Myiasis Cases

Data from the National Health, Safety and Agrifood Quality Service (Senasica) reveals a concerning trend. Between November 21, 2024, and April 18, 2025, a total of 869 cases of animal myiasis were confirmed across several states.chiapas reported the highest number of cases (487), followed by Tabasco (249), Campeche (116), Quintana Roo (13), and Yucatan (4). This widespread infestation in animals underscores the urgency of addressing the root causes and implementing effective control strategies.

Case Details: severity and Treatment

The 77-year-old woman is currently receiving treatment at the “Health City” regional hospital and is reported to be in stable condition. Though, she presents with a significant 3×3 centimeter wound in the right parietal region, exposing bone and extending up to 6 centimeters around the affected area. The presence of myiasis in this wound poses a serious challenge to her recovery.

The 50-year-old man’s case originated from a dog bite on his left leg on April 19. By April 23, he noticed larvae emerging from the wound, accompanied by intense pain, redness (erythema), and fever. He sought medical attention at the Tuzantán municipal services on April 25 and was later referred to the Huixtla Health Center, where six larvae were extracted. taxonomic analysis by Senasica personnel confirmed the presence of C.hominivorax larvae.

Clinical Manifestations and Potential Complications of Human Myiasis

The Ssa emphasizes that the clinical characteristics of myiasis in humans closely resemble those observed in animals. Myiasis affecting natural cavities, such as the nasal passages (rhinomiasis), is a common presentation. The larvae of C. hominivorax possess the ability to destroy cartilage and even penetrate the cranial cavity, possibly leading to severe complications.

miasis in humans shares clinical characteristics with those observed in animals.The myiasis of natural cavities are, in most cases, secondary to infestation by larvae of C. hominivorax.The invasion of the nostrils (rhinomiasis) is the most common presentation… The larvae of C. Hominivorax have the ability to destroy cartilage and the palatine vault, being able to extend to the sinuses and even reach the cranial cavity. Ocular affectation can result in the destruction of the eyeball.

Mexican Ministry of Health (ssa)

Ocular involvement can result in the destruction of the eyeball, highlighting the devastating consequences of untreated myiasis. Early diagnosis and prompt treatment are crucial to prevent severe tissue damage and potential long-term health issues.

Related Coverage

For further information on the screwworm issue and its impact, see our previous report: The screwworm returns; The parasite that reopens wounds between Mexico and the US.