Clinical vulnerability patterns in human Cochliomyia hominivorax myiasis in Southern Mexico: an exploratory analytical study

Introduction: Human myiasis caused by Cochliomyia hominivorax remains a neglected tropical zoonosis in Latin America despite regional eradication programs targeting the New World screwworm. Contemporary epidemiological and vulnerability patterns in Mexico are poorly characterized. We conducted an analytical exploratory study to describe clinical distribution and identify factors associated with complicated outcomes in confirmed human cases reported in Southern Mexico.

Methods: A retrospective observational exploratory study was conducted, including 33 laboratory-confirmed human cases reported in the National Epidemiological Surveillance System (epidemiological week 29, 2025). Variables analyzed included age, sex, anatomical location, comorbidities, and clinical outcomes. Comorbidity was defined as documented chronic clinical conditions in the registry (e.g., diabetes mellitus, neoplasms, vascular disease, chronic kidney disease, malnutrition, alcohol use disorder). Age was summarized using the median and interquartile range (IQR). Proportions were calculated with 95% confidence intervals (95% CIs) using the Wilson method. Associations were assessed using Fisher’s exact test and crude odds ratios (ORs) with Haldane correction.

Results: The median age was 60 years (IQR 48–74; range 17–87), and 63.6% were male (95% CI 46.6–77.8). Cephalic involvement was the most frequent presentation (45.5%; 95% CI 29.8–62.0). At least one comorbidity was present in 75.8% (95% CI 59.0–87.2), and ≥2 in 21.2%. Six patients (18.2%) had neoplastic disease, including skin cancer, basal cell carcinoma, lip cancer, tongue cancer, and parietal neoplastic lesions; all were located in the cephalic region (100%). Complicated outcomes occurred in 15.2% (95% CI 6.7–30.9), and case fatality was 3.0% (95% CI 0.5–15.3). One death occurred in a patient with multiple comorbidities; the specific cause of death was not publicly available.

Conclusions: Human Cochliomyia hominivorax myiasis in Southern Mexico predominantly affects patients with comorbidities and conditions favoring tissue exposure. The observed association between cephalic neoplasms and infestation suggests that exposed tumor lesions may play a key role in pathogenesis. These findings provide clinical evidence of vulnerability factors in this neglected zoonosis.