Gastrointestinal Myiasis Research Articles

Occurrence of Gasterophilus spp. in Weanling Foals in Southern Brazil

Background: The occurrence of gastrointestinal myiasis caused by Gasterophilus spp. larvae (Diptera: Oestridae) in adult horses has been widely characterized, however data on natural infestation in young foals have been lacking. This observation may be related to the absence of conclusive diagnosis in these individuals, most likely due to logistical or financial constraints. Gastric ulceration is a problem and a significant cause of morbidity in foals, particularly during the weaning stage; therefore, gasterophilosis should be included in the differential diagnosis. The primary purpose of this study was to determine the prevalence of gasterophilosis in 4- to 6-month-old weanling foals.Material, Methods & Results: Seventy-one healthy weanling foals were enrolled in the study. Physical assessment blood sampling and was completed in all foals before the commencement of the experiment. Gastroscopy examinations were performed under sedation (Detomidine 0.01 - 0.02 mg/kg) with a flexible endoscope inserted through nasogastric via. The lumen of the stomach was examined in order to search for botflies’ larvae. Following gastroscopy, foals were classified into 2 groups based on the presence of Gasterophilus spp. larvae in their stomachs: 1) Infected and 2) Not Infected. Infected foals received a single dose of commercial trichlorfon and albendazole equine oral gel and were stalled for 24 h. The passed feces were thoroughly examined, searching for elimination of larvae. A Total of 64% of the foals (n=45/71) harbored Gasterophilus spp. larvae in the stomach. Mild hyperemia in the gastric mucosa was observed in the attachment sites of the parasites. Physical assessment and hematological parameters’ data were analyzed with Shapiro-Wilk normality test. Comparison between groups for clinical signs, hematological parameters and Gasterophilus spp. infection rates were evaluated using the Kruskal-Wallis test or Student's t-test. Statistical significance was set at P < 0.05. There were no statistically significant variations in physical and hematological parameters between foals that were affected and those that were not infected. The larvae found in the feces were subjected to morphological examination, which confirmed the diagnosis of Gasterophilus intestinalis.Discussion: No systemic clinical indications compatible with Gasterophilus infestation were seen, as described in previous studies of horses infected with the parasite. No botfly eggs were observed in the hair of evaluated foals. During gastroscopy, mild hyperemic lesions in the gastric mucosa were observed in the larvae fixation sites. Although no changes in clinical or hematological parameters were noted, the confirmation of parasite presence is a cause for concern due to horses' tolerance for low infestation levels and poor diagnosis. Additionally, the presence of this myiasis in foals may be a significant stressor during the weaning period and should be included in the differential diagnosis of recurring abdominal pain. Furthermore, infected foals might be a reservoir for the parasite and, contribute to the elimination and spread of the larvae in the environment. Thus, inclusion of young horses in deworming protocols targeted to botfly larvae is needed. This is the first report of Gasterophilus intestinalis myiasis in foals in Brazil. Further research is necessary to fully understand the epidemiology and prevalence of this condition in young horses in Brazil, based on the findings of this study. Keywords: Gasterophilus intestinalis, cavity myiasis, gastroscopy, Oestridae.

Miasis gástrica e intestinal por Ornidia obesa (Diptera: Syrphidae) en humanos. Primer reporte en Colombia

Las miasis son infestaciones de tejidos de animales y humanos, causadas por larvas de moscas, las cuales tienen importancia manifiesta en Salud Publica. En la literatura biomédica Colombiana, son escasos los reportes referentes a los diferentes tipos de miasis que se presentan en los humanos. En este trabajo se reportan dos casos de pacientes con miasis gastrointestinal, donde los agentes etiológicos implicados fueron Ornidia obesa y Ornidia sp (Diptera: Syrphidae). La identificación taxonómica de las larvas halladas en ambos pacientes se realizó en el Instituto Colombiano de Medicina Tropical CES y fue confirmada en el Laboratorio del Departamento de Medicina Veterinaria Preventiva en Salud Animal de la Facultdad de Medicina Veterinaria y Zootecnia de la Universidad de Sao Paulo. Estos dos casos de miasis se constituyen en el primer reporte en Colombia.

Sequence variation in three mitochondrial genes among Gasterophilus intestinalis isolates from two distinct regions in China

Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. has a worldwide distribution. However, little information is available on the genetic variation of Gasterophilus spp. at the molecular level. In the present study, sequence variation was examined in three mitochondrial (mt) genes, namely mt cytochrome c oxidase subunit 1 (cox1), NADH dehydrogenase subunits 5 (nad5) and large subunit ribosomal RNA (rrnL), among G. intestinalis isolates originating from Heilongjiang Provience and Xinjiang Uygur Autonomous Region, China. The complete cox1, nad5, and rrnL gene sequences were amplified by PCR separately from adult G. intestinalis individuals and the amplicons were sequenced from both directions. The size of the sequences of cox1, nad5, and rrnL genes was 1539 bp, 1717 bp, and 1321 bp, respectively. The A + T contents of the sequences were 62.7–63.9% (cox1), 70–70.7% (nad5), and 74.5–74.9% (rrnL). The intra-specific sequence variations within G. intestinalis were 0.1–3.1% for cox1, 0.4–3.4% for nad5, and 0.1–1.5% for rrnL. Phylogenetic analyses based on the cox1 sequences using the Bayesian inference indicated that all the G. intestinalis isolates grouped together with high statistical support. These findings demonstrated clearly the usefulness of mt cox1, nad5, and rrnL sequences for the molecular identification and for studying population genetics of G. intestinalis in horses.

Sleep Duration, Obesity, and Asthma in Florida High School Students: Analysis of the Florida Youth Risk Behavior Survey (2009-2013)

A cross-sectional survey was performed to obtain current data on the gastrointestinal myiasis of horses in the provinces of Kostanay, Akmola and Karagandy, northern and central Kazakhstan. The stomach, small intestine and rectum of 148 slaughter horses were examined for Gasterophilus spp. larvae during a 26-month study period. All horses were infected with 2nd and 3rd stage larvae (mean intensity: 803 ± 350), and 22% of them harboured >1000 Gasterophilus spp. larvae each. Four species were identified: G. intestinalis (prevalence: 100%; mean intensity: 361 ± 240 larvae), G. haemorrhoidalis (100%; 353 ± 191), G. nasalis (100%; 73 ± 36) and G. pecorum (91.2%; 18 ± 10). Horses aged < 2 years were higher infected with Gasterophilus larvae than 2–4 years old animals. Both the prevalence and extremely high intensity of Gasterophilus infections of horses in these Kazakh regions suggest respective control measurements to improve the health and performance of the animals and to increase the economic income of horse owners.

Miasis gastrointestinal por &lt;i&gt;Eristalis tenax&lt;/i&gt; en Costa Rica

&lt;span&gt;Las miasis gastrointestinales son infestaciones poco frecuentes y de difícil identificación por su sintomatología inespecífica y por requerir la expulsión de las larvas para hacer un diagnóstico certero. Se presenta el primer caso reportado de miasis gastrointestinal por &lt;em&gt;Eristalis tenax&lt;/em&gt; en Costa Rica. La paciente es una mujer de 45 años, que reside en una zona rural con problemas de abastecimiento de agua potable. Presenta un cuadro de diarrea crónica, dolor abdominal, y sensación de cuerpo extraño en el ano y expulsión casual de larvas identificadas como &lt;em&gt;Eristalis tenax&lt;/em&gt;. Este reporte extiende el registro de casos de miasis gastrointestinales humanas por &lt;em&gt;Eristalis tenax&lt;/em&gt; en América hasta los 09°50' 55", el caso más septentrional en el continente Americano.&lt;/span&gt;

Gasterophilus spp. infections in horses from northern and central Kazakhstan

A cross-sectional survey was performed to obtain current data on the gastrointestinal myiasis of horses in the provinces of Kostanay, Akmola and Karagandy, northern and central Kazakhstan. The stomach, small intestine and rectum of 148 slaughter horses were examined for Gasterophilus spp. larvae during a 26-month study period. All horses were infected with 2nd and 3rd stage larvae (mean intensity: 803±350), and 22% of them harboured >1000 Gasterophilus spp. larvae each. Four species were identified: G. intestinalis (prevalence: 100%; mean intensity: 361±240 larvae), G. haemorrhoidalis (100%; 353±191), G. nasalis (100%; 73±36) and G. pecorum (91.2%; 18±10). Horses aged<2 years were higher infected with Gasterophilus larvae than 2–4 years old animals. Both the prevalence and extremely high intensity of Gasterophilus infections of horses in these Kazakh regions suggest respective control measurements to improve the health and performance of the animals and to increase the economic income of horse owners.

Persistent pediatric gastro-intestinal myiasis: A case report of fly larval infestation with musca domestica with review of literature

The occurrence of dipterous fly larvae in human is termed as human myiasis. Human myiasis can be classified based on clinical condition it causes like cutaneous myiasis, ocular myiasis, urogenital myiasis and intestinal myiasis. Based on the need for a particular host, myiasis can be divided as specific myiasis, semi-specific myiasis. Accidental myiasis results when the fly larvae are deposited/ingested by human resulting in infestation, which is also called as pseudomyiasis. Fly larvae may be present on the dead and decaying organic matter and domestic animals like dog and cats which are naturally infested with fly larvae and can be source for infection in children. Very few cases have been retrieved from literature on the occurrence of intestinal myiasis in children throughout the world. We report a case of two siblings in the same family infested with dipterous fly larvae.

Gastrointestinal Myiasis by Larvae ofSarcophagasp. andOestrussp. in Egypt: Report of Cases, and Endoscopical and Morphological Studies

Four cases of gastric or intestinal myiasis are reported. The cases contain 2 males (1 child 10 years old, and 1 adult 40 years old) and 2 females (1 girl 18 years old, and 1 adult 50 years old) from Minia Governorate, Southern Egypt. Three of them, including cases no. 1, 3, and 4, were gastric myiasis, and complained of offensive hematemesis of bright red blood. Minute moving worms, larvae of the fly, were found in the vomitus. On the other hand, case no. 2 had intestinal myiasis, and complained of abdominal distention, nausea, vomiting, and diarrhea. The stool of case 2 was mixed with blood, and minute moving worms were observed in the stool. Endoscopy was performed to explore any pathological changes in the stomach of the patients. The larvae were collected and studied macroscopically, microscopically, and us-ing a scanning electron microscope (SEM) to identify their species. Three different types of larvae were identified. The larvae isolated from case 1 were diagnosed as the second stage larvae of Sarcophaga species, and the larvae isolated from case 2 were the third stage larvae of Sarcophaga species. On the other hand, the larvae isolated from cases 3 and 4 were diagnosed as the third stage larvae of Oestrus species.

Cutaneous Myiasis: Diagnosis, Treatment, and Prevention

Myiasis, from the Greek myia for “fly,” has been defined as the infestation of live human or vertebrate animals with larvae of the insect order Diptera (flies), which feed on living or necrotic tissue. The majority of flies causing myiasis can be categorized into 1 of 2 groups, based on relationship with their hosts. Obligate parasites grow only on healthy tissue of live hosts whereas facultative parasites, associated usually with carrion, feces, or decaying plant material, can develop on necrotic tissue of living animals and tend not to invade healthy tissue. Accidental infestations represent a third category in which the eggs or larvae of saprophagous flies are inhaled or swallowed inadvertently with contaminated food (gastrointestinal myiasis). Myiasis can also be classified according to the site of infestation. Cutaneous myiasis involves the invasion of the skin, with the most common target being a wound, near which an obligatory or facultative parasitic fly will lay eggs. In “wound myiasis,” both healthy and necrotic tissues can be fed on by the larvae, depending on the conditions and species of fly involved. Other flies (eg, the human botfly Dermatobia hominis [L. Jr.] in tropical America, the “tumbu fly” Cordylobia anthropophaga [Blanchard and Berenger-Feraud] in tropical Africa, and Wohlfahrtia vigil [Walker] in North America) penetrate healthy skin and produce itchy sores that develop into painful boil-like lesions or furuncles, hence the term “furuncular myiasis.” Creeping myiasis is a type of cutaneous myiasis involving the migration of fly larvae underneath the skin. Apart from the skin, the eyes, ears, nose, and sinuses represent relatively common sites of attack whereas less common sites are the mouth, throat, urogenital, and gastrointestinal tracts. The invasion of body orifices is sometimes considered accidental myiasis, especially when the larvae cannot complete their development. The most severe cases of myiasis involve obligate parasites, typically those invading wounds or mucous membranes associated with body orifices (screwworm flies) in tropical America (Cochliomyia hominivorax Coquerel) or in the Old World (Chrysomya bezziana Villeneuve, Wohlfahrtia magnifica Schiner), although some facultative myiasis can be dangerous if left untreated. Myiasis occurs mainly in tropical and subtropical latitudes and often originates in these areas even when reported in temperate climates. The main contributing factors are probably the higher levels of exposure to myiasis-causing flies due to poorer clothing and hygiene conditions, combined with the increased aggressiveness of myiasis-causing flies in the tropics. Nevertheless, many cases acquired in temperate parts of Eurasia and North America, including Canada, have been described in the literature. Despite these records, human myiasis remains an unfamiliar illness for most physicians in North America; misdiagnosis and inappropriate treatment are common. Awareness of myiasis by health professionals *Doctoral Student, Laboratoire d’Organogenese Experimentale

Utility of Mitochondrial and Ribosomal Genes for Differentiation and Phylogenesis of Species of Gastrointestinal Bot Flies

Larvae of Gasterophilus spp. (Diptera: Oestridae) cause gastrointestinal myiasis of equids. However, their identification may be problematic due to morphological similarities between species infesting identical regions of the digestive tract. In this study, genes encoding for mitochondrial cytochrome oxidase I (COI) and for the 16S and 28S ribosomal subunits of the most commonly encountered Gasterophilinae subfamily species [i.e., Gasterophilus haemorrhoidalis (L.), Gasterophilus inermis (Brauer), Gasterophilus intestinalis (De Geer), Gasterophilus nasalis (L.), and Gasterophilus pecorum (F.)] were studied, together with Gyrostigma pavesii (Corti), a rhinoceros parasite, and Hypoderma lineatum (De Villers), as outgroup taxa. Analysis identified interspecific differences that allowed their unequivocal identification. The high genetic homology among the sequences of G. haemorrhoidalis and G. intestinalis (i.e., 100, 99.86, and 99.46% in the 28S, COI, and 16S genes, respectively) strongly support the hypothesis that they are morphotypes of the same species. Phylogenetic analyses (maximum-likelihood and parsimony) were performed using PAUP; all analyses supported monophyly of subfamily Gasterophilinae. This study confirms the utility of the COI and 16S and 28S rRNA genes to address diagnostic and phylogenetic questions in Gasterophilus species.

Species composition of Gasterophilus spp. (Diptera, Oestridae) causing equine gastric myiasis in southern Italy: Parasite biodiversity and risks for extinction

Horse gastrointestinal myiasis caused by larvae of Gasterophilus spp. (Diptera, Oestridae) flies has a worldwide distribution and, where present, it is primarily caused by larvae of Gasterophilus intestinalis and Gasterophilus nasalis. Other species, i.e., Gasterophilus inermis, Gasterophilus pecorum and Gasterophilus haemorrhoidalis, present in different or in the same regions of the gastrointestinal tract, were only occasionally reported in very limited areas of eastern European Countries and in central Italy. With the aim to contribute data on the species composition of Gasterophilus and on the seasonal variation of the infection pattern in southern Italy, 152 native horses were necropsied from January to December 2003 and Gasterophilus larvae were collected from the stomach, the small intestine and the rectum of each of them. On the whole, 125 (82.2%) horses were infected by larvae of Gasterophilus spp. and 214 second stage larvae (L2) and 13,342 third stage larvae (L3) collected. Five species of Gasterophilus were identified with the following prevalence: G. intestinalis = 95.2%, G. nasalis = 44.8%, G. inermis = 15.2%, G. pecorum = 2.6% and G. haemorrhoidalis = 0.8%. L3 were retrieved throughout the observation period with the highest mean burdens from January to August 2003 while the lowest mean was registered from September to November 2003. L2 were collected in February–March 2003 and from September to December 2003. The majority of the animals ( n = 66, 43.4%) were infected with a single Gasterophilus species, however, 45 animals (29.6%) harboured 2 species, 12 animals (7.9%) 3 species and 2 animals (1.3%) 4 species. The trend of abundance in the L3 of G. intestinalis and G. nasalis, the most represented species, was highly concordant ( r = 0.5, p < 0.001). A retrospective comparison of our results and of other data from four seasons of observation (1983–1986) in central Italy showed that the number of G. inermis, G. pecorum and G. haemorrhoidalis have been decreasing relative to G. intestinalis and G. nasalis which may suggest tendency toward the extinction of the three former species of Gasterophilus.

Gastrointestinal human myiasis caused by Eristalis tenax

The myiasis observed in Bariloche are characterized and the probable conditions under which the infestations took place established. The larvae obtained from faeces of 2 patients were identified as Eristalis tenax (Diptera: Syrphidae) according to Hartley (1961) and Organización Panamericana de la Salud keys (1962). These 2 cases of human gastrointestinal myiasis were the first to be registered in Bariloche (Patagonia, Argentina) and their characteristics were similar to those described for this species in other parts of the world. The lack of specific control measures in the domestic water supply system was the most probable cause of the infestation. This event extends the distribution of E. tenax and human gastrointestinal myiasis in South America to 41 degrees 03' S.