Genomic analyses of a livestock pest, the New World screwworm, find potential targets for genetic control programs.

The New World Screwworm fly, Cochliomyia hominivorax, is a major pest of livestock in South America and Caribbean. However, few genomic resources have been available for this species. A genome of 534 Mb was assembled from long read PacBio DNA sequencing of DNA from a highly inbred strain. Analysis of molecular evolution identified 40 genes that are likely under positive selection. Developmental RNA-seq analysis identified specific genes associated with each stage. We identify and analyze the expression of genes that are likely important for host-seeking behavior (chemosensory), development of larvae in open wounds in warm-blooded animals (heat shock protein, immune response) and for building transgenic strains for genetic control programs including gene drive (sex determination, germline). This study will underpin future experiments aimed at understanding the parasitic lifestyle of the screwworm fly and greatly facilitate future development of strains for efficient systems for genetic control of screwworm.

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.

Bovine freeze-dried blood as alternative for feeding of screwworm larvae / Sangre liofilizada bovina como alternativa para la alimentación de larvas del gusano barrenador del ganado

The myiasis caused by Cochliomyia hominivorax (Coquerel) or screwworm is considered one of the most traumatic and relevant to the region due to its economic implications and its importance in public health. The purpose of this study was to compare the reproductive and developmental indexes of screwworm using citrated and freeze-dried bovine blood, spray-dried bovine blood (currently used by Panama-United States Commission for the Eradication and Prevention of Screwworm ñacronym in spanish [Copeg]) and bovine citrated liquid blood. The use of freeze-dried arises through the premise that, due to its process of elaboration constitutes an alternative of better quality for the feeding of the screwworm in function of the integrity of sanguine proteins during its processing. For the comparison of the different diets, the following parameters were used: pH, total pupae weight, pupae size, total pupae volume, emergency percentage, oviposition percentage and hatching percentage. In the case of freeze-dried blood, it showed better mean (standard deviation) indexes of emergence, 83.42 (11.45), and 73.11 (15.97) (p = .01); and hatching, 89.70 (8.88), and 84.08 (8.29), (p = .004) compared to the diet based on spray-dried blood. By virtue of the above, freeze-dried blood proved to be a source of protein with potential to develop insect breeding programs.

La miasis causada por Cochliomyia hominivorax (Coquerel) o gusano barrenador del ganado (GBG) es considerada una de las más traumáticas y relevantes para la región debido a sus implicaciones económicas y su importancia en la salud pública. El propósito de este estudio fue comparar los índices reproductivos y de desarrollo del GBG con sangre bovina liofilizada citratada, sangre bovina secada por pulverización (actualmente utilizada por la Comisión Panamá-Estados Unidos para la Erradicación y Prevención del Gusano Barrenador del Ganado [Copeg]) y sangre líquida bovina citrata. El uso de liofilizado surge bajo la premisa de que, debido a su proceso de elaboración, constituye una alternativa de mejor calidad para la alimentación del GBG en función de la integridad de las proteínas sanguíneas durante su procesamiento. Para la comparación de las diferentes dietas, se utilizaron los siguientes parámetros: pH, peso total de las pupas, tamaño de pupas, volumen total de pupas, porcentaje de emergencia, porcentaje de oviposición y porcentaje de eclosión. En el caso de la sangre liofilizada, mostró mejores promedios (desviación estándar) de índices de emergencia, 83.42 (11.45) y 73.11 (15.97) (p = .01), y eclosión, 89.70 (8.88) y 84.08 (8.29) (p = .004) en comparación con la dieta basada en sangre secada por pulverización. En virtud de lo anterior, la sangre bovina liofilizada demostró ser una fuente de proteína con potencial para desarrollar programas de crianza de insectos.

Deconstructing the eradication of new world screwworm in North America: retrospective analysis and climate warming effects.

Before its eradication from North America, the subtropical-tropical new world screwworm fly Cochliomyia hominivorax (Coquerel) invaded southwestern temperate areas of the U.S.A., where it caused myiasis in wildlife and livestock. Outbreaks of the fly occurred during years when adult migrants were carried northward on North American monsoon winds from the northern areas of Mexico and south Texas. We deconstruct, retrospectively, the biology and the effect of weather on the eradication of the fly in North America. Screwworm was found to be an ideal candidate for eradication using the sterile insect technique (SIT) because females mate only once, whereas males are polygynous, and, although it has a high reproductive potential, field population growth rates are low in tropical areas. In northern areas, eradication was enhanced by cool-cold weather, whereas eradication in tropical Mexico and Central America is explained by the SIT. Despite low average efficacy of SIT releases (approximately 1.7%), the added pressure of massive SIT releases reduced intrinsically low fly populations, leading to mate-limited extinction. Non-autochthonous cases of myiasis occur in North America and, if the fly reestablishes, climate warming by 2045-2055 will expand the area of favourability and increase the frequency and severity of outbreaks.

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.

Wound myiasis: the role of entodermoscopy

Abstract: Although wound or traumatic myiasis is common in tropical countries, only recently cases associated with underlying dermatoses, such as seborrheic dermatitis and psoriasis, have been reported. We describe a patient with seborrheic dermatitis and an ulcerated lesion on the scalp, in which the dermatological examination with the aid of dermoscopy allowed the identification of larvae (maggots) compatible with infestation by Cochliomyia hominivorax. Treatment was performed with oral and topical ivermectin, followed by manual extraction of the larvae.

Wound myiasis: the role of entodermoscopy.

Although wound or traumatic myiasis is common in tropical countries, only recently cases associated with underlying dermatoses, such as seborrheic dermatitis and psoriasis, have been reported. We describe a patient with seborrheic dermatitis and an ulcerated lesion on the scalp, in which the dermatological examination with the aid of dermoscopy allowed the identification of larvae (maggots) compatible with infestation by Cochliomyia hominivorax. Treatment was performed with oral and topical ivermectin, followed by manual extraction of the larvae.

Efficacy of spinosad on the treatment of myiasis caused by Cochliomyia hominivorax (Diptera: Calliphoridae) in dogs.

The purpose of this study was to evaluate the overall efficacy, larval expulsion and larvicidal effect of spinosad on the treatment of myiasis caused by New World screwworm Cochliomyia hominivorax in naturally infested dogs. Six Beagle dogs presenting with myiasis were treated once with spinosad 560 mg, with dosages ranging from 43 to 577 mg/kg. Dogs were observed with 15 min post treatment, and with intervals of 15 min within the first hour followed by hourly evaluations up to six hours post-treatment. After this period, the remaining larvae were mechanically removed. Spontaneous expulsion of larvae was variable among dogs. All dogs received support treatment and were followed up for healing of the myiasis-associated lesion. On average, the highest larval expulsion occurred four hours after treatment. A single spinosad treatment had an overall efficacy of 79.7% (56.7-100%). The average larval expulsion rate was 73.3% (56.7-100%), reached its maximum within 6 h post-treatment, and the average larvicidal effect was only 23.7% (0-58.3%). No animal needed a second dosage 24 h post-treatment, lesions were completely healed within 8 days post-treatment. Despite not reaching the desirable 100% efficacy, spinosad treatment is an option in managing NSW myiasis, in conjunction with mechanical removal of maggots that remain in the lesion and support treatment.

Towards the automated identification of Chrysomya blow flies from wing images.

The Old World screwworm fly (OWSF), Chrysomya bezziana (Diptera: Calliphoridae), is an important agent of traumatic myiasis and, as such, a major human and animal health problem. In the implementation of OWSF control operations, it is important to determine the geographical origins of such disease-causing species in order to establish whether they derive from endemic or invading populations. Gross morphological and molecular studies have demonstrated the existence of two distinct lineages of this species, one African and the other Asian. Wing morphometry is known to be of substantial assistance in identifying the geographical origin of individuals because it provides diagnostic markers that complement molecular diagnostics. However, placement of the landmarks used in traditional geometric morphometric analysis can be time-consuming and subject to error caused by operator subjectivity. Here we report results of an image-based approach to geometric morphometric analysis for delivering wing-based identifications. Our results indicate that this approach can produce identifications that are practically indistinguishable from more traditional landmark-based results. In addition, we demonstrate that the direct analysis of digital wing images can be used to discriminate between three Chrysomya species of veterinary and forensic importance and between C. bezziana genders.

Case Report: Myiasis due to Cochliomyia hominivorax and Dermatobia hominis: Clinical and Pathological Differences between Two Species in Northern Peru.

Infestations caused by fly larvae (Myiasis) have been observed in patients with risk factors and in tropical zones. The aim of our study was to describe the clinical and epidemiological aspects and the risk factors associated with the occurrence of obligatory myiasis, as well as the therapeutic approach to patients. We identified the cases of myiasis diagnosed in two referral hospitals in northern Peru from January 2012 to December 2015 and included patients in whom larval development and a compatible clinical profile were observed. Epidemiological, clinical, analytical, diagnostic, therapeutic, and follow-up data were collected from clinical files. Nine clinical cases were compatible with a diagnosis of myiasis; of these, two were pediatric patients, one was a middle-aged adult, and six were elderly patients. Four of the nine patients were male. The identified species were Dermatobia hominis and Cochliomyia hominivorax. The therapeutic approach included antiparasitic therapy with ivermectin, antibacterial, and in some cases, anti-inflammatory drugs. Dermatobia hominis and C. hominivorax are the predominant species causing myiasis in northern Peru.

Cattle herd inspections and fly trapping for the detection of the Old World screw-worm fly (Chrysomya bezziana).

OBJECTIVES: To compare the sensitivity of inspections of cattle herds and adult fly trapping for detection of the Old World screw-worm fly (OWS). PROCEDURES: The incidence of myiases on animals and the number of OWS trapped with LuciTrap®/Bezzilure were measured concurrently on cattle farms on Sumba Island (Indonesia) and in peninsular Malaysia (two separate periods for the latter). The numbers of animal inspections and traps required to achieve OWS detection at the prevalent fly densities were calculated. RESULTS: On Sumba Island, with low-density OWS populations, the sensitivity of herd inspections and of trapping for OWS detection was 0.30 and 0.85, respectively. For 95% confidence of detecting OWS, either 45 inspections of 74 animals or trapping with 5 sets of 4 LuciTraps for 14 days are required. In Malaysia, at higher OWS density, herd inspections of 600 animals (twice weekly, period 1) or 1600 animals (weekly, period 2) always detected myiases (sensitivity = 1), while trapping had sensitivities of 0.89 and 0.64 during periods 1 and 2, respectively. For OWS detection with 95% confidence, fewer than 600 and 1600 animals or 2 and 6 LuciTraps are required in periods 1 and 2, respectively. CONCLUSIONS: Inspections of cattle herds and trapping with LuciTrap and Bezzilure can detect OWS populations. As a preliminary guide for OWS detection in Australia, the numbers of animals and traps derived from the Sumba Island trial should be used because the prevailing conditions better match those of northern Australia.

Oral myiasis caused by Cochliomyia hominivorax treated with ivermectin and nitrofurazone: case report.

Myiasis is the infestation of tissues and organs of animals and humans by certain dipteran fly larvae. This phenomenon is well-documented, especially among animals and people in tropical and subtropical areas. Oral myiasis is a rare condition that can be caused by several species of dipteran fly larvae. When the larvae are removed from the mouth, the tissues seem to recover with no subsequent complications and no need for further treatment. This article presents a case involving a patient with oral myiasis caused by Cochliomyia hominivorax and treated with ivermectin and nitrofurazone.

Histerocele total complicado con miasis a propósito de un caso / Histerocele myiasis complicated by a total of one case

Miasis es la infestación de órganos o tejidos por larvas de moscas. La infestación con larvas de mosca produce diversas manifestaciones según el sitio afectado y puede incluso, causar la muerte. No es una enfermedad común en humanos pero se observa con alguna regularidad en países neotropicales. Afecta con mayor frecuencia las áreas expuestas de la piel y se presenta raramente en ojos, nariz, senos paranasales, tracto urogenital o recto; en estos casos la infestación se asocia con traumas previos o secresiones purulentas que atraen a las moscas adultas. Se presenta el caso de una paciente femenina de 65 años de edad, con prolapso total del útero (histerocele grado IV) complicado con miasis específica por Cochliomya hominivorax.

Use of polyester pad as a new physical substrate for rearing Cochliomyia hominivorax coquerel (Diptera: Calliphoridae) larvae.

Polyester pad was utilized as solid support for rearing Cochliomyia hominivorax Coquerel larvae in liquid diet and compared with the ground meat diet. There were no significant differences in the mean third instar larvae and pupal weights, number of pupae, emergence and rearing efficiency. The tests were conducted through four consecutive generations, presenting no detectable effect in any of the life history parameters. We propose that the polyester pad can be used as solid support for rearing C. hominivorax larvae in liquid diets and can be reutilized reducing the costs of mass rearing.

Genetic approaches for studying myiasis-causing flies: molecular markers and mitochondrial genomics.

"Myiasis-causing flies" is a generic term that includes species from numerous dipteran families, mainly Calliphoridae and Oestridae, of which blowflies, screwworm flies and botflies are among the most important. This group of flies is characterized by the ability of their larvae to develop in animal flesh. When the host is a live vertebrate, such parasitism by dipterous larvae is known as primary myiasis. Myiasis-causing flies can be classified as saprophagous (free-living species), facultative or obligate parasites. Many of these flies are of great medical and veterinary importance in Brazil because of their role as key livestock insect-pests and vectors of pathogens, in addition to being considered important legal evidence in forensic entomology. The characterization of myiasis-causing flies using molecular markers to study mtDNA (by RFLP) and nuclear DNA (by RAPD and microsatellite) has been used to identify the evolutionary mechanisms responsible for specific patterns of genetic variability. These approaches have been successfully used to analyze the population structures of the New World screwworm fly Cochliomyia hominivorax and the botfly Dermatobia hominis. In this review, various aspects of the organization, evolution and potential applications of the mitochondrial genome of myiasis-causing flies in Brazil, and the analysis of nuclear markers in genetic studies of populations, are discussed.