Bot Fly Larvae Research Articles

Nasopharyngeal bot flies in red deer (Cervus elaphus) from southern Spain.

The nasopharyngeal bot flies Pharyngomyia picta and Cephenemyia auribarbis (Diptera: Oestridae) are parasites that have an impact on the health of wild ruminants. Little is known about their biological and epidemiological characteristics in multi-host habitats such as the Sierra de Cazorla, Segura y Las Villas Natural Park (CNP), in south-east Spain. This paper describes the main epidemiological features of bot fly larvae parasitising the population of red deer in CNP during 2003-2005. The results reveal an overall bot fly prevalence of 37.5%, with a P. picta and C. auribarbis co-infection rate of 12.5%. Although the statistical analyses were not significant(p > 0.05), a higher prevalence in males and in calves was observed, which has to be explained from a multifactorial viewpoint. Unfavourable climatic conditions during January induced the overwintering of larvae inside the host and, accordingly, a higher prevalence of the first instar (L1) was detected, while a higher prevalence of L2 and L3 was recorded in February and March. Further studies are needed to investigate in more detail the environmental characteristics that influence the chronobiology of bot flies in south-east Spain.

Bot Fly Parasitism of Allegheny Woodrats (Neotoma magister) in Virginia

The Allegheny woodrat (Neotoma magister) is a species of high conservation concern and relatively well-studied with respect to habitat use/associations, food habits, conservation genetics, and population trends. However, with the exception of raccoon roundworm (Baylisascaris procyonis) occurrence and etiology in woodrats, most disease and parasite ecology aspects for the woodrat are unknown. Herein, we examined the prevalence of bot flies (Cuterebra) over nearly three decades of woodrat surveys (1990–2018) in the central Appalachian Mountains of western Virginia. We use genetic analyses to identify recent bot fly specimen collections from a woodrat captured in 2017. Though highly variable from year to year, the overall prevalence of parasitism was low (typically < 4% of captures). As such, bot flies do not appear to be a widespread parasitic burden to Allegheny woodrats in Virginia. Genetic analysis of four collected bot fly larvae was inconclusive, as the genetic signature of these woodrat bots did not match any of the six bot species known to parasitize rodents and lagomorphs in the eastern United States. Further collections and genetic analyses will be needed to determine if the genetic database is incomplete or incorrect, or if our find is a new species of bot fly not yet taxonomically recognized.

First Report of Nasal Bot Fly (Cephenemyia jellisoni) in White-Tailed Deer (Odocoileus virginianus) Inhabiting Tropical Dry Forests in Central Mexico

This is the first report of nasopharyngeal myiasis by the larvae of Cephenemyia jellisoni infecting white-tailed deer (Odocoileus virginianus) from tropical dry forests in central Mexico. This study was conducted on hunted male deer within 2 wildlife management units located in the states of Puebla and Oaxaca. Bot fly larvae prevalence in both populations was 50% (95% CI: 21–78%, n = 12) with a median intensity of 4 (95% CI: 3–7). We recommend the implementation of a surveillance program at management units and the monitoring of female deer to determine differential gender effects.

Brood parasitic nestlings benefit from unusual host defenses against botfly larvae (Philornis spp.)

Brood parasitic birds lay their eggs into the nests of other birds, abandoning parental care of their nestlings to the unsuspecting hosts. Parasite and host nestlings may themselves be parasitized by botfly larvae (Philornis: Muscidae), which burrow under the nestlings’ skin and can seriously affect growth and survival. Here, we provide the first direct evidence that adult baywings (Agelaioides badius), the primary host of the specialist brood parasitic screaming cowbird (Molothrus rufoaxillaris), regularly remove botfly larvae from their own and parasitic nestlings by pulling them out of the nestlings’ skin. This is the only bird species known to remove botfly larvae. By combining nestling cross-fostering with video recording of baywing nests, we show that due to prompt removal, infection with botfly larvae had negligible effects on nestling growth and survival despite high prevalence. Our results provide the first direct observations for larva removal behavior in botfly hosts. Screaming cowbirds may benefit from using baywings as its main host, as larva removal by adult baywings reduces the costs of botfly parasitism. Infection by botfly larvae of the genus Philornis (Muscidae) causes nestling mortality in many Neotropical birds. Despite the lethal effects, most Philornis hosts studied so far lack specific defenses against these larvae. The grayish baywing (Agelaioides badius), primary host of the brood parasitic screaming cowbird (Molothrus rufoaxillaris), is the only species that, based on indirect evidence, would be able to remove Philornis larvae from infected nestlings. We provide the first direct evidence that adult baywings do indeed remove botfly larvae from their own nestlings as well as from parasitic cowbird nestlings and that this unusual defense may increase the survival of own and screaming cowbird nestlings at infected nests.

Diagnosis of ophthalmomyiasis externa by dermatoscopy.

Ophthalmomyiasis in humans caused by the larvae of the sheep nasal botfly (Oestrus ovis) and is a rare phenomenon in Israel. We describe the utilization of the dermatoscope as a diagnostic tool for the facilitation of early diagnosis of conjunctivitis due to the infestation of the eyes by the sheep nasal botfly in two patients. After the physical removal of the larvae with the help of a cotton swab applicator under a slit lamp examination and the topical use of antibiotics, the clinical symptoms improved within 1–2 days. Undoubtedly the dermatoscope played a crucial role leading to the definitive diagnosis and immediate therapeutic intervention.

Breeding biology of the endangered Yellow Cardinal Gubernatrix cristata in Brazil

The Yellow Cardinal, Gubernatrix cristata, has a small geographic range in Brazil, Uruguay, and Argentina. We studied the natural history of the only known Brazilian population of this “Endangered” species (∼50 individuals), which is socially monogamous and may breed cooperatively. During two breeding seasons (October to February 2013–2015), we monitored nests and described the main breeding traits. The breeding season started from the first week of October, with a peak of active nests in mid-November and lasted until mid-February. We found 32 nests, of which 30 were monitored. Female built the open-cup nests in six days (n = 1). All nests were built on Prosopis trees, on average at 2.4 m from the ground. Modal clutch size was three eggs (n = 19), and female incubated for 13 days on average (n = 7). Hatching rate was 76% and nestlings fledged after 16 days (n = 6). Nestling survival rate was 67% with mean productivity of 1.6 fledglings/successful nest. Shiny Cowbird, Molothrus bonariensis, parasitized nests of the Yellow Cardinal, with a frequency of 67% and intensity of 1.9 egg per parasitized nest (1–4 eggs; n = 13). Parasitism in nestlings by botfly larvae (Philornis sp.) occurred in 33% of nests with nestlings. Nest predation was the main cause of nest losses (73%) and we recorded a Geoffroy’s Cat, Leopardus geoffroyi, preying on a nest with eggs. The probability of success using the Program MARK was 13%. Fledgling survival rate during the first month outside the nest was 62% (8/13 fledglings). We found a longer breeding season, occurrence of second broods, and higher rates but fewer nest losses due to brood parasitism in comparison to the Argentinian population. We highlight the importance of natural history studies for the conservation of different populations of the same species.

Botfly infections impair the aerobic performance and survival of montane populations of deer mice, Peromyscus maniculatus rufinus

Abstract Elevations &gt;2,000 m represent consistently harsh environments for small endotherms because of abiotic stressors such as cold temperatures and hypoxia. These environmental stressors may limit the ability of populations living at these elevations to respond to biotic selection pressures—such as parasites or pathogens—that in other environmental contexts would impose only minimal energetic‐ and fitness‐related costs. We studied deer mice (Peromyscus maniculatus rufinus) living along two elevational transects (2,300–4,400 m) in the Colorado Rockies and found that infection prevalence by botfly larvae (Cuterebridae) declined at higher elevations. We found no evidence of infections at elevations &gt;2,400 m, but that 33.6% of all deer mice, and 52.2% of adults, were infected at elevations &lt;2,400 m. Botfly infections were associated with reductions in haematocrit levels of 23%, haemoglobin concentrations of 27% and cold‐induced VO2max measures of 19% compared to uninfected individuals. In turn, these reductions in aerobic performance appeared to influence fitness, as infected individuals exhibited 19‐34% lower daily survival rates. In contrast to studies at lower elevations, we found evidence indicating that botfly infections influence the aerobic capabilities and fitness of deer mice living at elevations between 2,000 and 2,400 m. Our results therefore suggest that the interaction between botflies and small rodents is likely highly context‐dependent and that, more generally, high‐elevation populations may be susceptible to additional biotic selection pressures. A plain language summary is available for this article.

First report on nasal myiasis in an alpaca \u201cVicugna pacos\u201d \u2013 a case report

BackgroundAn infestation of bot fly larvae causes myiasis which is known to cause respiratory symptoms in ruminants. There are reports of bot fly larvae in llamas, but to our knowledge there are no previous reports of nasal myiasis due to bot flies in alpacas (“Vicugna pacos”).Case presentationThe following case report describes a neutered male alpaca showing sneezing and mild nasal discharge. Endoscopic examination of the upper respiratory tract revealed bot fly larvae in one nostril. After treatment with doramectin, there was no evidence of living bot fly larvae visible in the nostril.ConclusionBot fly larvae should be considered as a potential cause of respiratory symptoms in alpacas. In the present case, a treatment with doramectin was successful.

Effect ofCuterebra fontinella(Mouse Bot Fly) on the Movement ofPeromyscus leucopus(White-footed Mouse)

Peromyscus leucopus (White-footed Mouse) is a common host for Cuterebra fontinella (Bot Fly), but few studies of this interaction in the southeastern US exist. We assessed the movement of White-footed Mice infested with Bot Flies at 9 riparian woodland sites in Spartanburg County, SC. Our objectives were to determine the prevalence of bot warbles, lumps under the skin containing Bot Fly larva, on White-footed Mice and if the warbles reduced mouse movement. We found that 17.4% of mice had bot warbles during the August trapping period, with a mean intensity of 1.21 ± 0.09 (SE) per mouse. Male and female mice did not differ in the prevalence of bot infestation. Bot-infested mice did not differ from uninfested mice in their mean squared distance from center of activity (MSD). During May, mice that later became infested with a bot warble in August, did not differ in MSD from mice that did not become infested, suggesting that greater movement does not heighten the risk of infestation. Our data show that bot warbles do not reduce the movement of White-footed Mice and our findings add to the growing consensus that Bot Flies do not have a strong negative effect on the ecology of White-footed Mice.

Ocular Manifestations of Mosquito-Transmitted Diseases.

Of the 3,548 known mosquito species, about 100 transmit human diseases. Mosquitoes are distributed globally throughout tropical and temperate regions where standing water sources are available for egg laying and the maturation of larva. Female mosquitoes require blood meals for egg production. This is the main pathway for disease transmission. Mosquitoes carry several pathogenic organisms responsible for significant ocular pathology and vision loss including West Nile, Rift Valley, chikungunya, dengue viruses, various encephalitis viruses, malarial parasites, Francisella tularensis, microfilarial parasites, including Dirofilaria, Wuchereria, and Brugia spp., and human botfly larvae. Health care providers may not be familiar with many of these mosquito-transmitted diseases or their associated ocular findings delaying diagnosis, treatment, and recovery of visual function. This article aims to provide an overview of the ocular manifestations associated with mosquito-transmitted diseases.

The prevalence of Gasterophilus intestinalis (Diptera: Oestridae) in donkeys (Equus asinus) in Egypt with special reference to larvicidal effects of neem seed oil extract (Azadirachta indica) on third stage larvae.

Gasterophiline larvae are of veterinary and medical importance caused specific equine intestinal myiasis. Gasterophilus intestinalis (Botfly larvae) had a wide geographical distribution. The present study explores the prevalence rate of G. intestinalis 3rd stage larvae in Egypt from January- December 2017; besides, in vitro trials to control of this larvae and evaluation of this trial using Scanning Electron Microscope (SEM) and histopathology of treated larvae. In the present study, the 3rd larval stage of G. intestinalis was found in clusters in the epithelium of the investigated stomach and infested with prevalence rate 97.2%. The highest collected numbers of larvae were found in two months; March and August (570 & 520 larvae) and lowest numbers (200 larvae) were collected in October, November, and December. The calculated LC50 and LC90 values of neem seed extract were 707.9 ppm and 1090.7 ppm. The different alteration was recorded after exposure to oil extract which showed some destruction on cuticle surface as folded and corrugated cuticle, destruction of maxillae with pits on its surface, disfigure and irregularity of cephalic spines. Histopathology of exposed G. intestinalis larvae showed different changes as thinning of cuticle at the different level (exocuticle, endocuticle, cell layers), degeneration of epithelial cells of the gut and different degree of necrosis was described. Life cycle of G.intestinalis was followed up after treatment with neem seed extract.

Report of a Case of Human Nasal Myiasis Caused By Second Instar Larvae of Oestrus Ovis in CHU Oran: Review of Literature

Myiasis is the invasion of human and animal organs and tissues by dipteran larvae. This is a case report of a human nasal myiasis caused by the second instar larvae of the sheep bot fly, Oestrusovis. The cases of human myiasis at Oestrusovis are accidental and rare, mainly affecting the eyes. In the literature, there are only sporadic reports of nasal myiasis. We present a new case of nasal myiasis caused by the second instar larvae of Oestrusovis in a 29-year-old male patient, originally from OuedRhiou in the west of Algeria, whois a medical doctor suffering from signs of rhinosinusitis.

Breeding biology of Chalk-browed Mockingbird Mimus saturninus in a natural savanna of central Brazil

The Chalk-browed Mockingbird Mimus saturninus (Mimidae) is a common bird in savannas, grasslands, and farmlands, also occurring in urban areas. We studied its breeding biology in a Cerrado savanna inside a reserve at central Brazil, from 2003 to 2013. We monitored 74 nests, which were usually found in the more open phytophysiognomies of the Cerrado. The breeding season lasted from late August to late December. The nest is a cup built with twigs and generally placed on shrubs and small trees. Mean nest height above the ground was 1.3 ± 0.5 m (n = 73). Mean clutch size was of 2.9 ± 0.9 eggs (n = 63), ranging from one (possibly an incomplete clutch) to six eggs (possibly a communal nest). Incubation was asynchronous, the incubation period lasted 14.2 ± 0.9 days (n = 17 nests), and the nestling period lasted 14.1 ± 1.2 days (n = 21 nests). Nestling infestation by botfly larvae was common (60% of nests), but did not cause any nest loss. Its breeding season was similar to most birds of the Cerrado region, but its clutch size was larger. The Chalk-browed Mockingbird breeding biology in central Brazil is similar to that reported from the southern part of its distribution. The species is capable of multiple broods, has cooperative breeding and shows evidence of communal breeding, a rare behavior reported so far for Mimidae. The main difference between our study and those conducted with the Chalk-browed Mockingbird in Argentina, is the very low prevalence of brood parasites, demonstrating the importance of reserves to allow breeding with low brood parasitism rates.

An incidental case of gastric pseudomyiasis in Canis latrans (Carnivora: Canidae) by a rabbit bot fly Cuterebra sp. (Diptera: Oestridae)

An incidental case of gastric pseudomyiasis in the coyote Canis latrans by a rabbit bot fly Cuterebra sp. is documented. In a coyote scat not entirely solid but somewhat watery and surrounded by mucous in the municipality of Perote, state of Veracruz, 2 myiasigenous fly larvae of the family Oestridae were found. Specimens were studied in the laboratory and found to correspond to a Cuterebra species of the buccata species-group, of which their normal hosts are hares and rabbits (Lagomorpha). Their characteristics are similar to those described for Cuterebra buccata, but the level of taxonomic knowledge of the larval stage of this family does not permit a confident identification to species. The coyote scat from which the bot fly larvae were recovered indicates that damage in the digestive tract of rabbit-predators may have serious consequences in individuals, and an increment in the abundance of these flies may favor a health problem that diminishes the life quality, not only for normal hosts, but also for their predators.

Aberrant Migration of Cuterebra Larvae in 2 Domestic Rabbits (Oryctolagus cuniculus)

This report describes 2 cases of cuterebriasis in an atypical host, the domestic rabbit (Oryctolagus cuniculus). Case 1 describes the clinical presentation, diagnosis and management of ophthalmomyiasis externa caused by a bot fly larva. Case 2 outlines the clinical syndromes, postmortem, and histopathological findings associated with Cuterebra larval migrans through the respiratory and central nervous systems. In both cases the presence of the parasite caused significant debilitating disease in the host animals, with fatal consequences in one patient.

Morphological and molecular identification of nasopharyngeal bot fly larvae infesting red deer (Cervus elaphus) in Austria.

Nasopharyngeal myiases are caused by larvae of bot flies (Diptera: Oestridae), which have evolved a high specificity for their hosts. Bot flies (n = 916) were collected from 137 (57.6 %) out of 238 red deer (Cervus elaphus) hunted in Vorarlberg and Tyrol (Western Austria). After being stored in 75 % ethanol, larvae were identified to species level and developmental stage using morphological and morphometric keys. Larvae were also molecularly characterized by polymerase chain reaction (PCR) amplification and partial sequencing of the mitochondrial cytochrome oxidase subunit I gene. Morphological and molecular analysis allowed identification of larvae as Cephenemyia auribarbis and Pharyngomyia picta. Genetic variations were also examined within the specimens collected in both geographical locations.

Parasitological survey of Polish primitive horses (Equus caballus gmelini Ant.): influence of age, sex and management strategies on the parasite community

Summary An extensive analysis of the relationship between age, sex, and different types of management strategies relative to the gastrointestinal parasite community of Polish primitive horses was performed on 124 horses maintained in nine farms from four regions of Poland. The horses (96 females and 28 males) were housed in three types of management strategies: stabled (ST), free-ranging (FR) and semi-free (SF). These horses also were divided into three age groups: &lt;3 years, 3 – 10 years and &gt;10 years old. The gastrointestinal parasites were collected following deworming of all horses with anthelmintics containing the macrocyclic lactones and praziquantel. Totally, 66,192 parasite specimens were collected and identified. The analysis of dependence of horse infection with intestinal nematodes using sex, age and management strategies demonstrated that females had significantly heavier infections of strongylids. Young horses (&lt;3 years old) had higher infections of Parascaris equorum and Strongyloides westeri. Free ranging horses were more infected with strongylids, Oxyuris equi and Gasterophilus intestinalis. Thirty-five nematode species, one cestode and one species of the botfly larvae of Gasterophilus were found. Diagnostic deworming examination revealed presence of Parascaris equorum in 27.4 %, Oxyuris equi in 38.7 %, Habronema muscae in 16.9 %, Anoplocephala perfoliata in 42.7 % and Gasterophilus intestinalis in 46.8% in the Polish primitive horses examined. Strongyloides westeri presence was confirmed only by fecal samples examination; threadworms were not observed in these horses after deworming. In the strongylid community, 31 species (6 of subfamily Strongylinae and 25 of Cyathostominae) were found. Significant differences in prevalence of separate strongylid species, or their proportions in the communities were not observed between females and males, or between age groups (p &gt; 0.05). The highest species diversity (n=30 or 31) was observed in the FR horses, the lowest (n=15) – in ST horses. The FR horses had higher prevalence and proportion of large strongyles in the community, in comparison to SF or ST horses (p &lt; 0.05).

Detection of Rickettsia helvetica in Ixodes ricinus infesting wild and domestic animals and in a botfly larva (Cephenemyia stimulator) infesting roe deer in Germany

Ixodes ricinus is a well-known vector of different human pathogens including Rickettsia helvetica. The role of wild mammals in the distribution and probable maintenance of Rickettsia in nature is still to be determined. We therefore investigated various parasites from different wild mammals as well as companion animals for the presence of Rickettsia. A total of 606 I. ricinus, 38 Cephenemyia stimulator (botfly larvae), one Dermacentor reticulatus, 24 Haematopinus suis (hog lice) and 30 Lipoptena cervi (deer flies) were collected from free-ranging animals during seasonal hunting, and from companion animals. Sample sites included hunting leases at three main sampling areas and five additional areas in West and Central Germany. All collected parasites were screened for Rickettsia spp. and I. ricinus were investigated for tick-borne encephalitis virus (TBEV) in addition. While no TBEV was detected, the minimum infection rate (MIR) of I. ricinus with Rickettsia was 4.1% referring to all sampling sites and up to 6.9% at the main sampling site in Koblenz area. Sequencing of a fragment of the ompB gene identified R. helvetica. Approximately one third (29.5%) of the animals carried Rickettsia-positive ticks and the MIR in ticks infesting wild mammals ranged from 4.1% (roe deer) to 9.5%. These data affirm the widespread distribution of R. helvetica in Germany. One botfly larva from roe deer also harboured R. helvetica. Botfly larvae are obligate parasites of the nasal cavity, pharynx and throat of cervids and feed on cell fragments and blood. Based on this one might hypothesise that R. helvetica likely induces rickettsemia in cervids thus possibly contributing to maintenance and distribution of this rickettsia in the field.

Ultrasound Visualization of Atypical Abscess Ultimately Containing Bot Fly Larva

BackgroundBecause of the rise in community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA), presentations to the emergency department for the evaluation of cutaneous abscesses have risen dramatically over the past 2 decades. Soft tissue point of care ultrasound (POCUS) differentiates abscess from cellulitis, determines the size and shape, and characterizes the contents of the abscess. It has been shown to improve medical decision-making and therefore the emergency management of cutaneous abscesses over physical examination alone. Case ReportWe report a case of an unusual nonhealing abscess in an 18-year-old woman with a recent history of foreign travel where soft tissue POCUS identified motion within the abscess pocket. This changed the management of the case, leading to the diagnosis of bot fly myiasis. Why Should an Emergency Physician Be Aware of This?Clinicians should entertain a broader differential for an apparent abscess and consider liberal use of soft tissue POCUS in these cases.

Cephenemyia stimulator (Diptera) infection in roe deer (Capreolus capreolus) from Kraków area, southern Poland.

The aim of the study was to determine the prevalence of botfly (Diptera: Oestridae) larvae infection in roe deer populations (Capreolus capreolus) in the Kraków area on the basis of necropsy and questionnaire surveys. Hunters were surveyed about the age and sex of hunted animals, and the origin of their habitat. All parasite specimens were identified to species in the laboratory. The parasites were found in the nasal cavities, esophagus, and larynx of male roe deer aged 3-8 years, living in forest habitats. The level of infection was relatively low (13%), with the intensity ranging from 1 to 10 larvae per host. Although no fly larvae were found during the dissection of roe deer carcasses, the parasites received from the hunters were identified as Cephenemyia stimulator botflies. These findings are supported by the evidence drawn from the questionnaires completed by the hunters. parasites, Cephenemyia stimulator, Capreolus capreolus, necropsy, questionnaire study, Poland.