Costa Rica - Screwworm Myiasis cases in humans increase

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Screwworm Myiasis Cases Increase

Friday, April 25, 2025. According to data from the Ministry of Health's Surveillance Directorate, 34 confirmed cases of Screwworm Myiasis in Humans have been reported based on laboratory results issued by the National Veterinary Services Laboratory (LANASEVE – SENASA) for the year 2025.

From February 12 to December 31, 2024 (Epidemiological Weeks 7 to 52), a total of 40 confirmed cases of this disease were reported, with a rate of 0.8 per 100,000 inhabitants.

Screwworm myiasis is a parasitic disease caused by the larval or maggot stage of the fly Cochliomyia hominivorax. It affects all warm-blooded animals, including humans. The fly lays its eggs in wounds and/or mucous membranes of body orifices, invading living tissues such as the skin, eyes, mouth, nose, genitals, and other cavities.

The Ministry of Health urges the public to follow these prevention and control recommendations:

• Maintain personal hygiene, wash your hands regularly with soap and water.
• Monitoring, treatment and hygiene of injuries according to the recommendation of the treating physician.
• Go to a health facility if you experience symptoms associated with the disease, such as: pain, discomfort, and itching at the site of the injury, reddening of the skin, a wound with discharge, a sensation of movement, and frequently, visible eggs and/or larvae can be seen in the wound.
• Maintain vigilance and control over animal care, performing frequent checkups, treating all wounds, and reporting to the animal health authorities (SENASA) any worm infestation in farm or domestic animals.

It is recalled that the ministry already has the National Guideline for the Surveillance of Screwworm Myiasis in Humans, which establishes the epidemiological approach to confirmed cases of this disease, so that surveillance has allowed timely detection and diagnosis in people in public and private health centers, in the following link you can find said guideline: https://www.ministeriodesalud.go.cr...-miasis-por-gusano-barrenador-en-humanos/file

https://www.ministeriodesalud.go.cr...umentan-casos-de-miasis-por-gusano-barrenador
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Published on 12/15/2025 at 8:00pm Health

Alajuela, San José and Limón most affected by screwworm myiasis: cases rise to 91 this year

For the same period of the previous year, 38 cases were recorded in humans.

By
Mariana Mena

Costa Rica has accumulated 91 cases of screwworm myiasis in humans so far in 2025, according to the most recent data from the Ministry of Health.

The figure confirms a sustained increase in the disease this year and more than doubles the records for the same period in 2024, when 38 cases were recorded.

According to the Ministry of Health, cases have been reported in all seven provinces, however the most affected are Alajuela, San José and Limón.

The records by province are:

Alajuela: 21 cases
San Jose: 17 cases
Lemon: 17 cases
Guanacaste: 11 cases
Heredia: 10 cases
Puntarenas: 10 cases
Cartago: 5 cases
...
Older adults, the most affected group

On the other hand, the analysis by age shows that the disease has a greater impact on the adult population, especially older adults.

According to the epidemiological report, the following was recorded:

People aged 65 or over: 45 cases
People aged 20 to 64: 39 cases
Under 20 years old: 7 cases

"The risk of contracting the disease increases with age, especially when there are skin lesions, reduced mobility, or pre-existing health conditions," the ministry noted.

On the other hand, screwworm myiasis continues to be more prevalent in men. The following cases were reported during 2025:

64 cases in men, with a rate of 2.5 per 100,000 inhabitants
27 cases in women, with a rate of 1.0 per 100,000 inhabitants

Experts have indicated that this difference is associated with factors such as occupational exposure, contact with animals, and wounds not treated promptly.

Symptoms and prevention measures

Authorities also reiterated the importance of identifying early symptoms associated with this disease, including:

Pain, discomfort, or itching at the site of the injury
Skin redness
Wound with discharge
Sensation of movement in the affected area
Visible presence of eggs or larvae

Regarding prevention, the Ministry of Health recommended:

Maintain personal hygiene and wash your hands frequently.
Treat and cover skin lesions properly
Go to a health center immediately if you experience symptoms
Check the animals regularly
Report maggot infestations to Senasa for timely attention

https://observador.cr/alajuela-san-...-gusano-barrenador-casos-suben-a-91-este-ano/