17 Screwworm Infections Reported in Mexico

Mexico City, Mexico — The National Epidemiological Surveillance System (Sinave), under the Secretariat of Health (Ssa), confirmed 17 cases of human myiasis caused by the screwworm parasite as of Friday, June 13. The infections have been reported exclusively in the states of Campeche and Chiapas, with the majority—15 cases—occurring in Chiapas.

Details of the Outbreak

The affected individuals include 13 men and four women. Among the confirmed cases, seven involve infestations in the head, while one notable case involves a 36-year-old man from Villa Comaltitlán, Chiapas, with an infection in the genital region. The youngest patient is a 25-year-old resident of Chiapas, and the oldest is an 86-year-old from Campeche.

Hospitalizations have risen from four on June 9 to seven by June 13. Three of the hospitalized patients have cancer, and one is suspected of having a human immunodeficiency virus (HIV) infection.

Rapid Increase in Cases

Sinave reported the first two cases of human myiasis on May 7. In just over five weeks, the number of confirmed infections surged to 17. The Ssa had previously warned of a potential rise in cases due to an ongoing screwworm plague affecting livestock in several southern states.

"The reproduction of these flies is closely linked to the presence of warm-blooded animals. Therefore, an increase in animal myiasis cases can lead to a rise in human infections," the agency stated in its Epidemiological Bulletin.

Clinical Characteristics and Risks

The Ssa noted that human myiasis shares clinical characteristics with cases observed in animals. "Miasis in natural cavities is, in most cases, secondary to infestation by Cochliomyia hominivorax larvae. Nasal cavity invasion (rhinomyiasis) is the most common presentation," the bulletin explained.

The agency further warned that C. hominivorax larvae can destroy cartilage and the palatal vault, potentially spreading to the paranasal sinuses and even reaching the cranial cavity. "Ocular involvement can result in the destruction of the eyeball," the Ssa detailed.

Ongoing Monitoring

Health authorities continue to monitor the situation, emphasizing the connection between livestock infestations and human cases. The outbreak remains concentrated in Campeche and Chiapas, with no reports of spread to other regions.