Reemerging/Notifiable Diseases to Watch.

Reemerging and notifiable diseases of cattle and bison continue to pose potential risks to their health and lives and affecting production and the livelihoods of producers. It is essential to understand the clinical presentation of these diseases to watch for possible incursions and infections and to immediately report your suspicions to your State and Federal Animal Health Officials. Three of these reemerging and notifiable diseases of cattle and bison, malignant catarrhal fever, bluetongue virus, and New World screwworm, are presented in this article for increased awareness to consider as a differential if examinations present suggestive clinical signs.

MIASIS OCULAR Y BUCAL, A PROPÓSITO DE DOS CASOS / MYASIS EYE AND MOUTH, BY THE WAY OF TWO CASES

La palabra "miasis" proviene del griego, "myia" que significa mosca. La enfermedad corresponde a los daños causados por la invasión de larvas de moscas a tejidos del hombre u otros vertebrados

The term 'Myiasis' originates from the ancient Greek word 'myia', meaning 'fly'. This disease refers to tissue damage caused by the infestation of fly larvae in humans or other vertebrates

First report of the efficacy of a fluralaner-based pour-on product (Exzolt® 5%) against ectoparasites infesting cattle in Brazil.

BACKGROUND: This study describes the effectiveness of a novel active pharmaceutical ingredient, fluralaner (isoxazoline class), against important ectoparasites infesting cattle in Brazil. METHODS: A total of 13 studies involving a 5% fluralaner-based pour-on formulation (Exzolt 5%; further referred to as Exzolt) were conducted. Specifically, the effectiveness of this formulation was studied against Rhipicephalus microplus (6 studies), Cochliomyia hominivorax larvae (4 studies), Dermatobia hominis larvae (1 study) and Haematobia irritans flies (2 studies). RESULTS: The therapeutic efficacy of Exzolt was found to exceed 98% at 4 days post treatment (DPT), while persistent efficacy (> 90% efficacy) against repeated infestations of R. microplus was observed for up to 79 DPT. In field studies, ≥ 98% therapeutic efficacy was demonstrated at all study sites by 7 DPT, and a persistent efficacy (> 90% efficacy) was observed for 42, 49 or 56 DPT. Exzolt prevented C. hominivorax eggs from developing to the larval stage, thus mitigating the development of myiasis in cattle naturally and artificially infested with this screworm. The efficacy of Exzolt against D. hominis larvae was 98% at 3 DPT, while persistent efficacy (> 90% effectiveness) was found to last for up to 70 DPT. Against H. irritans, Exzolt showed therapeutic efficacy (≥ 90%) within the first day of treatment at both study sites, while persistent efficacy (≥ 90%) was observed for 7 DPT at one site and for 21 DPT at the other site. CONCLUSIONS: Overall, the results from these studies confirm that Exzolt is therapeutically efficacious against the most important ectoparasites infesting cattle in Brazil. The novel active pharmaceutical ingredient, fluralaner, provides a new treatment option for farmers to control cattle ectoparasites, especially where there is resistance to other chemical classes. In addition, an effective control of ectoparasites will improve overall cattle health and well-being as well as production.

Morphological and Molecular Characterizations of Cochliomyia hominivorax (Diptera: Calliphoridae) Larvae Responsible for Wound Myiasis in French Guiana.

Myiasis is an ectoparasitic infection caused by the larvae of true flies (Diptera). We came across a rather rare case of myiasis in an immunocompetent 34-year-old man from French Guiana with advanced wound myiasis masquerading as cavitary myiasis and a history of cholesteatoma surgery in the left ear. The Diptera larvae responsible for the disease were isolated and identified using morphological and molecular approaches as Cochliomyia hominivorax. We underline the importance of this parasitosis as the second case of myiasis caused by C. hominivorax and the first case of wound myiasis in this overseas department of France and its incidence in pre-urban areas of the capital, Cayenne, in South America.

Case report on Cochliomyia hominivorax (Coquerel, 1858) and Co. macellaria (Fabricius, 1775) (Calliphoridae, Diptera) myiasis prior to death: Implications on postmortem interval estimation.

The most important contribution of forensic entomology is the estimation of the postmortem interval (PMI) or time since death. The forensic entomologist assumes that the biological clock of necrophagous insects that develop by feeding on cadaver tissues begins when the victim's biological clock is turned off. However, tissues can be invaded while the host is still alive (called myiasis), so the period of activity of necrophagous insects would not be indicative of PMI. The aim of this work was, through the presentation of a case report, to highlight the importance of expertise in the identification of necrophagous species associated with a corpse and their type of relationship in order to avoid an erroneous estimation of PMI. The corpse of a woman, missing for 14 days, was found outdoors in a small river 15 cm deep. Her corpse had numerous lesions infested with dipteran larvae that were collected during autopsy. Entomological evidence included second and third instar larvae of Cochliomyia hominivorax and Co. macellaria. The obligate parasitic nature of Co. hominivorax as a primary producer of myiasis and secondary of Co. macellaria allowed us to establish the time when the victim was still alive and from there to estimate the PMI.

A chromosomal-scale reference genome of the New World Screwworm, Cochliomyia hominivorax.

The New World Screwworm, Cochliomyia hominivorax (Calliphoridae), is the most important myiasis-causing species in America. Screwworm myiasis is a zoonosis that can cause severe lesions in livestock, domesticated and wild animals, and occasionally in people. Beyond the sanitary problems associated with this species, these infestations negatively impact economic sectors, such as the cattle industry. Here, we present a chromosome-scale assembly of C. hominivorax's genome, organized in 6 chromosome-length and 515 unplaced scaffolds spanning 534 Mb. There was a clear correspondence between the D. melanogaster linkage groups A-E and the chromosomal-scale scaffolds. Chromosome quotient (CQ) analysis identified a single scaffold from the X chromosome that contains most of the orthologs of genes that are on the D. melanogaster fourth chromosome (linkage group F or dot chromosome). CQ analysis also identified potential X and Y unplaced scaffolds and genes. Y-linkage for selected regions was confirmed by PCR with male and female DNA. Some of the long chromosome-scale scaffolds include Y-linked sequences, suggesting misassembly of these regions. These resources will provide a basis for future studies aiming at understanding the biology and evolution of this devastating obligate parasite.

Number of rainy days in a week influencing screwworm navel myiasis in beef calves and efficacies of injectable and topical antiparasitics.

Rainfall incidence as a risk factor for umbilical myiasis by Cochliomyia hominivorax in newborn beef cattle and the preventive and curative efficacies of injectable and topical products against its larvae were evaluated. The prevalence of navel myiasis did not differ between sex, however, it did differ between seasons of the year, independent of animal sex, with it being higher in the rainy season than in the dry season for both sexes (males 64.6%, females 62.1%). During the rainy season, rains occurred intermittently and the number of rainy days in a week had a direct influence on prevalence, with an increase (≥87%) in the number of calves with navel myiasis caused by C. hominivorax. When it rained intermittently for four, five and six days in a week during the rainy season, calves had ≈12, 24 and 11 times greater chances, respectively, of having navel myiasis compared to a week without rain during the rainy season. The injectable products did not reach preventive efficacies higher than 35%, while all treatments of topic products reached 100% preventive efficacy at 10 days post-treatment. Only the formulations with 30% dichlorfenthion and 0.32% fipronil achieved 100% curative efficacy. The results reinforce the need for intensified inspection and healing of the umbilicus during the rainy season, mainly during rainier weeks. Furthermore, topical formulations may be a better alternative as a preventive treatment than avermectin formulations. However, the curative efficacy of the topical product containing dichlorvos did not demonstrate a relationship with preventive efficacy for newborn calves.

Children hospitalized for myiasis in a reference center in Uruguay / Niños hospitalizados por miasis en un centro de referencia de Uruguay

Abstract Background: Myiasis is an emerging disease caused by tissue invasion of dipteran larvae. In Uruguay, Cochliomyia hominivorax and Dermatobia hominis are the most frequent species. This study aimed to describe the epidemiological and clinical characteristics and the follow-up of children < 15 years hospitalized for myiasis in a reference center in Uruguay between 2010 and 2019. Methods: We conducted a descriptive and retrospective study by reviewing medical records. We analyzed the following variables: age, sex, comorbidities, origin, the month at admission, clinical manifestations, other parasitoses, treatments, complications, and larva species identified. Results: We found 63 hospitalized children: median age of 7 years (1 month-14 years), 68% of females. We detected risk comorbidities for myiasis (33%), of which chronic malnutrition was the most frequent (n = 6); 84% were from the south of the country; 76% were hospitalized during the summer. Superficial and multiple cutaneous involvements were found in 86%: of the scalp 50, furunculoid type 51, secondary to C. hominivorax 98.4%, and to D. hominis in 1.6%. As treatments, larval extraction was detected in all of them, surgical in 22%. Asphyctic products for parasites were applied in 94%, ether in 49. Antimicrobials were prescribed in 95%; cephradine and ivermectin were the most frequent. About 51% presented infectious complications: impetigo was found in 29, cellulitis in 2, and abscess in 1. Conclusions: Myiasis predominantly affected healthy schoolchildren during the summer months and was frequently associated with ectoparasites. Superficial infestation of the furuncle-like scalp by C. hominivorax was the most frequent form. Infectious complications motivated hospitalizations.

Resumen Introducción: La miasis es una enfermedad emergente producida por la invasión tisular por larvas de dípteros. En Uruguay, Cochliomyia hominivorax y Dermatobia hominis son las especies más frecuentes. El objetivo de este estudio fue describir las características epidemiológicas y clínicas, y el seguimiento, de niños menores de 15 años hospitalizados por miasis en un centro de referencia del Uruguay entre 2010 y 2019. Métodos: Se llevó a cabo un estudio descriptivo y retrospectivo mediante la revisión de las historias clínicas. Se analizaron las siguientes variables: edad, sexo, comorbilidad, procedencia, mes al ingreso, cuadro clínico, otras parasitosis, tratamientos, complicaciones y especie de larva identificada. Resultados: Se encontraron 63 casos de niños hospitalizados, con una mediana de edad de 7 años (rango: 1 mes a 14 años) y el 68% de sexo femenino. Se identificó comorbilidad de riesgo para miasis (33%), siendo la desnutrición crónica la más frecuente (n = 6). El 84% eran procedentes del sur del país y el 76% fueron hospitalizados en los meses estivales. Se encontró afectación cutánea superficial y múltiple en el 86%: de cuero cabelludo en 50, de tipo forunculoide en 51, secundaria a C. hominivorax en el 98.4% y a D. hominis en el 1.6%. Se realizó extracción larvaria en todos los casos, que fue quirúrgica en el 22%. Se aplicaron productos asfícticos para parásitos en el 94%, con éter en 49 niños. Se prescribieron antimicrobianos en el 95%; los más usados fueron cefradina e ivermectina. El 51% presentaron complicaciones infecciosas: 29 impétigo, 2 celulitis y 1 absceso. Conclusiones: La miasis afectó predominantemente a escolares sanos y durante los meses estivales, y se encontró frecuentemente asociada con ectoparasitosis. La infestación superficial del cuero cabelludo de tipo forunculoide por C. hominivorax fue la forma más frecuente. Las complicaciones infecciosas motivaron las hospitalizaciones.

Children hospitalized for myiasis in a reference center in Uruguay.

BACKGROUND: Myiasis is an emerging disease caused by tissue invasion of dipteran larvae. In Uruguay, Cochliomyia hominivorax and Dermatobia hominis are the most frequent species. This study aimed to describe the epidemiological and clinical characteristics and the follow-up of children < 15 years hospitalized for myiasis in a reference center in Uruguay between 2010 and 2019. METHODS: We conducted a descriptive and retrospective study by reviewing medical records. We analyzed the following variables: age, sex, comorbidities, origin, the month at admission, clinical manifestations, other parasitoses, treatments, complications, and larva species identified. RESULTS: We found 63 hospitalized children: median age of 7 years (1 month-14 years), 68% of females. We detected risk comorbidities for myiasis (33%), of which chronic malnutrition was the most frequent (n = 6); 84% were from the south of the country; 76% were hospitalized during the summer. Superficial and multiple cutaneous involvements were found in 86%: of the scalp 50, furunculoid type 51, secondary to C. hominivorax 98.4%, and to D. hominis in 1.6%. As treatments, larval extraction was detected in all of them, surgical in 22%. Asphaltic products for parasites were applied in 94%, ether in 49. Antimicrobials were prescribed in 95%; cephradine and ivermectin were the most frequent. About 51% presented infectious complications, impetigo was found in 29, cellulitis in 2, and abscess in 1. CONCLUSIONS: Myiasis predominantly affected healthy schoolchildren during the summer months and was frequently associated with ectoparasites. Superficial infestation of the furuncle-like scalp by C. hominivorax was the most frequent form. Infectious complications motivated hospitalizations.

Efficacy of afoxolaner (NexGard®) on the treatment of myiasis caused by the New World screwworm fly Cochliomyia hominivorax (Diptera: Calliphoridae) in naturally infested dogs.

New World screwworm (NWS) myiasis is an infestation by Cochliomyia hominivorax larvae that consume the living tissue of warm-blooded animals, including humans. Domestic dogs are among the potential hosts of these flies that lay their eggs on the edges of wounds. NWS myiasis cases can be fatal if untreated. Treatment with parasiticides must be fast-acting, long-lasting and show 100% efficacy, since open wounds can be reinfested. Afoxolaner is a molecule from the isoxazoline family with proven ectoparasiticide action against fleas, ticks and mites in dogs. Fourteen healthy client-owned dogs, naturally infested by C. hominivorax larvae, were treated with afoxolaner (NexGard®) as per label recommendations, providing at least the minimum dosage of 2.5 mg/kg. Maggot infestations were classified as light (fewer than 10 larvae), mild (from 10 to 20 larvae) or severe (more than 20 larvae), according to the number of larvae found in the wound and/or collected from the ground after treatment. Twenty-four hours post-treatment, infested lesions were carefully inspected and collected larvae were counted and classified as live or dead. All maggots were identified as second and third instar larvae of C. hominivorax and were found dead within 24 h after treatment, demonstrating 100% larvicidal efficacy against C. hominivorax.

New World screwworm (Cochliomyia hominivorax) myiasis in feral swine of Uruguay: One Health and transboundary disease implications.

BACKGROUND: Feral swine (Sus scrofa) are highly invasive and threaten animal and human health in the Americas. The screwworm (Cochliomyia hominivorax) is listed by the World Organization for Animal Health as a notifiable infestation because myiasis cases affect livestock, wildlife, and humans in endemic areas, and outbreaks can have major socioeconomic consequences in regions where the screwworm has been eradicated. However, a knowledge gap exists on screwworm infestation of feral swine in South America, where the screwworm is endemic. Here, we report screwworm infestation of feral swine harvested in Artigas Department (Uruguay), where the Republic of Uruguay shares borders with Brazil and Argentina. METHODS: Myiasis caused by the larvae of screwworm were identified in feral swine with the support and collaboration of members of a local feral swine hunting club over a 3-year period in the Department of Artigas. Harvested feral swine were examined for the presence of lesions where maggots causing the myiasis could be sampled and processed for taxonomic identification. The sites of myiasis on the body of infested feral swine and geospatial data for each case were recorded. The sex and relative size of each feral swine were also recorded. Temperature and precipitation profiles for the region were obtained from public sources. RESULTS: Myiases caused by screwworms were recorded in 27 of 618 the feral swine harvested. Cases detected in males weighing > 40 kg were associated with wounds that, due to their location, were likely caused by aggressive dominance behavior between adult males. The overall prevalence of screwworm infestation in the harvested feral swine was associated with ambient temperature, but not precipitation. Case numbers peaked in the warmer spring and summer months. CONCLUSIONS: This is the first report on myiasis in feral swine caused by screwworm in South America. In contrast to myiasis in cattle, which can reach deep into host tissues, screwworms in feral swine tended to cause superficial infestation. The presence of feral swine in screwworm endemic areas represents a challenge to screwworm management in those areas. Screwworm populations maintained by feral swine may contribute to human cases in rural areas of Uruguay, which highlights the importance of the One Health approach to the study of this invasive host species-ectoparasite interaction.

Molecular basis of resistance to organophosphate insecticides in the New World screw-worm fly.

BACKGROUND: The emergence of insecticide resistance is a fast-paced example of the evolutionary process of natural selection. In this study, we investigated the molecular basis of resistance in the myiasis-causing fly Cochliomyia hominivorax (Diptera: Calliphoridae) to dimethyl-organophosphate (OP) insecticides. METHODS: By sequencing the RNA from surviving larvae treated with dimethyl-OP (resistant condition) and non-treated larvae (control condition), we identified genes displaying condition-specific polymorphisms, as well as those differentially expressed. RESULTS: Both analyses revealed that resistant individuals have altered expression and allele-specific expression of genes involved in proteolysis (specifically serine-endopeptidase), olfactory perception and cuticle metabolism, among others. We also confirmed that resistant individuals carry almost invariably the Trp251Ser mutation in the esterase E3, known to confer OP and Pyrethroid resistance. Interestingly, genes involved in metabolic and detoxifying processes (notably cytochrome P450s) were found under-expressed in resistant individuals. An exception to this were esterases, which were found up-regulated. CONCLUSIONS: These observations suggest that reduced penetration and aversion to dimethyl-OP contaminated food may be important complementary strategies of resistant individuals. The specific genes and processes found are an important starting point for future functional studies. Their role in insecticide resistance merits consideration to better the current pest management strategies.

Lysenko and the Screwworm Fly-When Politics Interferes with Science and Public Health.

In the One Health scenario, a deep understanding of the dynamics potentially threatening the development and implementation of useful pest and vector management tools is of key importance. The New World screwworm fly, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), is characterized by a wide host range. It acts as an important agent of myiasis in humans and warm-blooded animals in the Neotropics, and has been eliminated from a wide region through genetic methods. Of note, Serebrovsky had already proposed in 1940 the principles of autocidal control by the translocation of segments between two chromosomes, but his work was negated by Lysenko, based on the negation of Mendelian genetics. This entomological case study emphasizes the danger of politics interfering with science, a still contemporary hot issue. The negation of global warming or current pandemics are further examples of this noxious influence.

[Myiasis by Cochliomyia hominivorax in Argentina]. / Miasis por Cochliomyia hominivorax en la Argentina.

Miasis is the infestation of man and animals by larvae of flies belonging to the order Diptera, suborder Cyclorrapha. Eighty percent of miasis in Argentina is caused by Cochliomyia hominivorax, a species that induces pronounced tissue invasion and destruction, and results in severe clinical forms. Because of the aggressiveness of its larvae, it is important to reach a specific etiological diagnosis. We present four cases of miasis by C. hominivorax in two patients living in the city of Buenos Aires but working in a rural area and two patients living in the Greater Buenos Aires.

Miasis es la infestación de humanos y animales por larvas de dípteros ciclorrafos con invasión y destrucción tisular. Cochliomyia hominivorax es responsable del 80% de las miasis en la Argentina. Es importante realizar el diagnóstico etiológico específico debido a la agresividad de las larvas de esta especie, las que pueden provocar cuadros clínicos graves. Presentamos cuatro casos de miasis por C. hominivorax. Dos de los pacientes residían en la ciudad de Buenos Aires y trabajan en zona rural, y los otros dos residían en el Gran Buenos Aires.

Miasis por Cochliomyia hominivorax en la Argentina / Myiasis by Cochliomyia hominivorax in Argentina

Miasis es la infestación de humanos y animales por larvas de dípteros ciclorrafos con invasión y destrucción tisular. Cochliomyia hominivorax es responsable del 80% de las miasis en la Argentina. Es importante realizar el diagnóstico etiológico específico debido a la agresividad de las larvas de esta especie, las que pueden provocar cuadros clínicos graves. Presentamos cuatro casos de miasis por C. hominivorax. Dos de los pacientes residían en la ciudad de Buenos Aires y trabajan en zona rural, y los otros dos residían en el Gran Buenos Aires.

Miasis is the infestation of man and animals by larvae of flies belonging to the order Diptera, suborder Cyclorrapha. Eighty percent of miasis in Argentina is caused by Cochliomyia hominivorax, a species that induces pronounced tissue invasion and destruction, and results in severe clinical forms. Because of the aggressiveness of its larvae, it is important to reach a specific etiological diagnosis. We present four cases of miasis by C. hominivorax in two patients living in the city of Buenos Aires but working in a rural area and two patients living in the Greater Buenos Aires.

First report of myiasis in dogs caused by Cochliomyia hominivorax (Coquerel 1858) in Colombia.

This paper reports for the first time in Colombia, two myasis cases caused by Cochliomyia hominivorax in stray dogs. Clinical examination of both patients revealed fever and a large wound at the palpebral level on the right side, and multiple perforating wounds in the right posterior limb where larvae were found. The treatment applied was the manual removal of larvae in the dogs, and subsequent eye enucleation in one dog due to the total loss of the upper right eyelid and the severe mechanical damage that the cornea received. Treatment was reinforced with repellents applied around the wounds and antibiotics. This finding of Cochliomyia hominivorax in stray dogs in Colombia raises concerns about the potential of dogs serving as a reservoir for human infection in the region.

A review on the occurrence of Cochliomyia hominivorax (Diptera: Calliphoridae) in Brazil / Revisão da ocorrência de Cochliomyia hominivorax (Diptera: Calliphoridae) no Brasil

Abstract Cochliomyia hominivorax (Coquerel, 1858), the New World screwworm, causes primary myiasis in wild and domestic animals in tropical and subtropical regions of Brazil. Although this species is considered to occur throughout the country, organized information about its recorded distribution has not been available until now. This article aimed to provide a comprehensive review of the historical and current data published on both immature (myiasis) and adult stages of C. hominivorax in Brazil. A total of 174 articles were found; of these, 141 articles reported myiasis cases in cattle (146 records), humans (68 records), and other mammalian hosts (40 records), and captures of adult flies were reported in 33 articles. C. hominivorax is widespread in Brazil, having been recorded in 208 municipalities in all major biomes of the country.

Resumo Cochliomyia hominivorax (Coquerel, 1858), a mosca-da-bicheira, causa miíase primária em animais silvestres e domésticos em regiões tropicais e subtropicais do Brasil. Embora esta espécie seja considerada de ocorrência em todo o país, informações organizadas sobre sua distribuição com base em registros não estavam disponíveis até o momento. Este artigo teve como objetivo fornecer uma revisão abrangente dos dados históricos e atuais publicados sobre o registro de estágios imaturos (miíase) e adultos de C. hominivorax, no Brasil. De 174 artigos encontrados, 141 relataram casos de miíase em bovinos (146 relatos), humanos (68 relatos) e outros mamíferos hospedeiros (40 relatos) e capturas de adultos de C. hominivorax foram registradas em 33 artigos. C. hominivorax encontra-se amplamente distribuída no Brasil, tendo sido registrada em 208 municípios brasileiros em todos os principais biomas do país.

Using ecological niche models to describe the geographical distribution of the myiasis-causing Cochliomyia hominivorax (Diptera: Calliphoridae) in southern South America.

In southern South America, namely Argentina and Chile, Cochliomyia hominivorax (Coquerel) is the main myiasic agent on humans and domestic animals. The distribution pattern of the species is poorly known and the southern limit of its geographic distribution is unclear. The aims of this study are to elucidate the basic environmental factors associated with occurrence of this myiasic species, evaluation of models constructed on the basis of occurrence data based on adult specimen records to predict geographic occurrence of myiasis, evaluation of unsurveyed sites of high potential of occurrence of the species, and recognition and prioritization of areas that need medical control and specific prophylaxis practices related to this pest. The maximum entropy modeling system (Maxent) was used. Maps of potential distribution of C. hominivorax were produced using two different datasets, models obtained with all localities known for the species (combining medical data and taxonomic data) and only-taxonomic models (excluding medical data). The results obtained include an updated compilation of occurrence of the species in Argentina and Chile. Predictive models obtained in this work indicated that large areas of central-eastern territory of Argentina has the potential for C. hominivorax occurrence, probably reaching the parallel 42° S as is indicated by the complete datasets. Only-taxonomic models fail to predict those myiasic cases occurring in the nearer areas of the Andean chains. The main variables associated with the distribution of C. hominivorax were, alternatively, isothermality or minimum temperature of the coldest month. These results provide a new analytical resource of high potential for the prevention of myiasis and to supports further epidemiological studies.

Pin-Site Myiasis Caused by Screwworm Fly in Nonhealed Wound, Colombia.

Pin-site myiasis is an underreported complication of surgical interventions. We present a case of myiasis caused by the New World screwworm fly (Cochliomyia hominivorax) in a pin site of a chronic nonhealed wound 12 years after the intervention. This infection apparently was the result of poor perfusion of the leg.

Epidemiological analysis of the New World screwworm (Cochliomyia hominivorax) in Ecuador.

The New World screwworm (Cochliomyia hominivorax) is an obligate parasite that affects warm-blooded animals. It causes myiasis in livestock and humans, which is a problem for animal production and public health. The health and economic burden of myiasis on livestock production is largely unknown in Ecuador. We investigated the presence of the screwworm and analysed the epidemiology and spatial and temporal trends of myiasis in cattle farms of San Miguel de Los Bancos county. In total, epidemiological questionnaires were conducted in 110 farms, which were subsequently monitored for 12 months. The findings show that the initial and final prevalences in farms were 70% and 61.81%, respectively, and the average monthly prevalence was 15.08%. The initial and final prevalences in animals were 3.87% and 4.60% for bovines and 2.91% and 3.36% for all animals examined. The average percentage of new cases reported per month was 17.68% with a minimum of 10 and a maximum of 28 cases in October and May 2015, respectively. The cumulative incidence estimated that the risk for non-infested farms to become infested could reach 100% in approximately 6 months. The incidence rate is 168 per 1,000 farms at risk-monthly. The annual incidence was 459 per 10,000 for bovines at risk-annually. An analysis of hotspots based on the Getis-Ord Gi* index revealed no temporally stable hot spot, but one temporally stable cold spot, suggesting that most of the study area is generally favourable to infestation, except one cluster of farms.