Myiasis in a dog in MexicoThe following is a case from a small community in Huejutla, Northern part of Hidalgo state, central Mexico. History: A small wound was observed by the owners in the dorsal area of a 6 year-old mix breed dog. The owners applied methylene blue, but at day 5 they noticed progression in the size of the lesion and was taken to a veterinary clinic the following day (Images 1 and 2). During clinical examination the dog had a large amount of larvae in the wound. The patient was anesthetized with approximately 150 fly larvae removed. The wound was cleaned, and the dog received topical and systemic therapy including antibiotics. The dog fully recovered after treatment. Larvae were submitted in ETOH 70% in a sealed container to the official center for New World Screwworm identification in Mexico (SENASICA). This case has been provided by: Justiniano González Anaya1, Uriel M. Valdez-Espinoza2, Consuelo Almazán3 1Private clinical practice in Huejuetla, Hidalgo, Mexico. 2 Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuarias, Centro Nacional de Investigación Disciplinaria en Salud Animal e Inocuidad, Carretera Federal Cuernavaca - Cuautla No. 8534, Colonia Progreso, Jiutepec, C.P. 62574, Morelos, México. 3 Laboratorio de Inmunología y Vacunas (LINVAS), Facultad de Ciencias Naturales, Universidad Autónoma de Querétaro. Avenida de las Ciencias S/N. Juriquilla, Qro., CP 76230, Mexico. Image 1: Affected dog. Image 2: Dorsal lesion. Cochliomyia hominivorax, (New World Screwworm-NWS)
Is a parasitic fly attracted to open wounds, mucosal surfaces and the umbilical area in newborns, where female flies deposit eggs. These eggs hatch in approximately 24 hours and molt into larval instars 1 to 3 where they feed on healthy tissues (~ 1 week), causing extensive damage that requires prompt treatment. When the third larval instar is mature, it drops to the ground to pupate in the environment where depending on temperature and humidity, the fly emerges from the pupa after 7 to 54 days. The lifespan of the adult flies last between 2 and 4 weeks, with the males mating only once. This reproductive feature has been utilized to eradicate the NWS by the sterile insect technique. As this emerging pest has been recently detected in the USA, it is important to inspect animals, submit larvae for prompt identification, be in close contact with state veterinarians and insure that infested food animals properly treated are safe for consumption. Image 3: Dorsal lesion with larvae. Image 4: Larvae removed from dog. (Red arrows pointing at dorsal pigmented tracheal trunks, blue arrows indicate posterior spiracles used for diagnosis, black circle indicates long mouth hooks) |
