Report on Gasterophilus spp. (Diptera, Gasterophilidae) of Horses in Algeria: Prevalence, Intensity, and Monthly Variations

The composition, prevalence, and seasonal dynamic of Gasterophilus species were studied at the slaughterhouse of Constantine region (East Algeria) in 128 horses over an 18 months period. Our survey revealed that 124 (96.9%) horses were infected with a mean intensity of 161 larvae of Gasterophilus spp. Four species of Gasterophilus were identified; Gasterophilus intestinalis and G. nasalis were by far the predominant species with 95.3% and 77.3% respectively, followed by G. haemorrhoidalis (14.0%) and G. pecorum (10.1%). The age, sex, and breed of horses did not affect the distribution of the infection. Second-stage larvae (L2) of G. intestinalis were absent between April and July and present in higher numbers between December and February. In addition, third-stage larvae (L3) were few in number, mainly from September to November, a consequence of their fecal elimination and suggesting that the effective period of adult activity of G. intestinalis is autumn. Therefore, the population dynamics of G. nasalis shows that its activity is two months longer and occurs earlier than that of G. intestinalis. The incidence of G. pecorum infection was linked to the rainiest months.

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 3^rd 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 3^rd 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.

Gasterophilus intestinalis (Diptera: Oestridae) in the diaphragmatic muscle: An unusual finding

Larval forms of the bot-fly Gasterophilus are obligate parasites commonly found in the gastrointestinal tract of equids, causing intestinal myiasis. Five species are reported so far in Italy, mostly observed during necroscopy, located in different portion of gastrointestinal tract of equids: G. intestinalis, G. nasalis, G. inermis, G. pecorum and G. haemorrhoidalis. An unusual finding of larval Gasterophilus intestinalis deeply inserted into the diaphragmatic muscle is here reported. Due to the uncommon localization, to the absence of clinical signs related to myiasis and subsequent uncertainty of species identity, identification was performed using an integrative taxonomical approach combining morphology with molecular tools for confirmatory reasons. This finding adds information on migration patterns of erratic larval forms in G. intestinalis, a feature of interest as gasterophiliasis is among the less studied intestinal myiasis of horses.

A Rare Case of Gastric Myiasis in a Lion Caused by Gasterophilus intestinalis (Diptera: Gasterophilidae)-Case Report

Myiasis is the infection caused by a variety of dipterous (fly) larvae in vertebrate's tissue (man and domestic or wild animals). Species of Gasterophilus are obligate parasite of horses, donkeys, zebras, elephants and rhinoceroses. There are records worldwide, but mostly, in tropical and subtropical regions. This case report describes a type of gastric myiasis caused by G. intestinalis in an old lion in a zoo in Sistan, southeast Iran. Myiasis in lions is rarely reported and this is the first report of gastric myiasis in lion.

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.

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.