Report in Europe of nasal myiasis by Rhinoestrus spp. in horses and donkeys: seasonal patterns and taxonomical considerations

Two species of Rhinoestrus (i.e. Rhinoestrus purpureus (Brauer) and Rhinoestrus usbekistanicus Gan) cause nasal myiasis in horses, donkeys and zebras. In the past 15 years myiasis caused by R. purpureus has been reported in Egypt and by R. usbekistanicus in Senegal and Niger, both in horses and in donkeys. With the aim to investigate the presence of this myiasis in autochthonous horses and donkeys from southern Italy and to study the seasonal trend of larval infection, 212 native horses were necropsied in two slaughterhouses in the Apulia region (site A) from January to November 2003, and 120 native horses and two donkeys in one slaughterhouse in Sicily (site B) from January to October 2003. Thirteen of 212 and 5 of 120 horses examined from sites A and B, respectively, were infected by nasal bot fly larvae. Both donkeys examined were positive. Two hundred and thirteen larvae, representing all stages, were collected from the throat region, the turbinates and beyond the lamina cribrosa of the ethmoid bone, in the cerebral cavity. Third larval stages were retrieved from April to September with the highest mean burden in site A in May and in July in site B. The simultaneous presence all three larval stages at site B suggests the existence of two or more overlapping generations. Larvae were identified on the basis of peritreme structures and arrangement of the spines on the dorsal surface of the third segment. Some L3 collected from sites A and B presented morphological characteristics of both R. usbekistanicus and R. purpureus. The presence of mixed features on the L3 of Rhinoestrus collected from the same animals may be explained by the existence of a single species of Rhinoestrus presenting different morphotypes or of two species of Rhinoestrus which are both present in southern Italy since this area is midway between eastern and African countries where these two species have been reported.     

Ovine cutaneous myiasis: Effects on production and control

Ovine cutaneous myiasis ('fly strike') remains a major sheep health problem in many areas of the world. Myiasis risk is the result of a complex interaction of factors, such as fly and host abundance, host susceptibility, climate and, critically, husbandry and management strategies, all of which change seasonally in space and time. Given the complexity of the interacting factors, changes in myiasis incidence are hard to predict, as accordingly are the optimal husbandry responses required to manage the problem. Here the important risk factors are briefly reviewed and the future changes in myiasis incidence under conditions of anticipated climate change are considered. It is concluded that future work should focus in particular on evaluating the optimum use of integrated management, such as the combination of insecticide and trap use, in different environments under a range of farming regimes.     

Current trends in screwworm myiasis in the Caribbean region

In a random sample of animal producers and animal health personnel, 33% of the respondents in Trinidad, 15% in Guyana, 11% in Suriname and 9% in Jamaica recalled at least one case of human myiasis due to Cochliomyia homivorax (Coquerel). During 1981, respondents in Surinam (88%), Jamaica (90%), Guyana (85%) and Trinidad and Tobago (82%) found at least one case of myiasis in their livestock, occurring mainly in cattle, pigs and dogs. Feral animals, e.g. jaguars, were also found to be infested. The initial wounds were mainly the umbilicus of neonates, and arbitrary wounds, and vampire bites were also affected. Fifty-three to 78% of all respondents examined their livestock daily for wounds and infestation by the screwworm. Annual estimates of losses (in U.S. dollars) due to surveillance and medication ranged from $4.82 to $10.71 per animal. Nationally, these losses amount to $0.30 million (Surinam), $1.02 million (Trinidad and Tobago), $4.33 million (Guyana) and $6.78 million (Jamaica). Figures for other losses, arising from failure to thrive, reduction in milk production and hide injury due to screwworm activity were not available. Most producers found that the greatest screwworm infestation occurred in the wet season, and most described it as second in importance to Boophilus spp. ticks as a pest of livestock, but of greater significance than biting flies, such as tabanids and stable flies. Eradication of the screwworm from the islands of Jamaica and Trinidad and Tobago can be recommended, but in Surinam and Guyana eradication seems feasible only on the 100-km wide coastal strips where most human and livestock populations exist.     

Traumatic myiasis by Wohlfahrtia magnifica in Italy

Seven farms, two in Central Italy and five in Southern Italy, were visited for the presence of larvae-infested wounds. Ninety-six (3%) out of 3129 sheep examined had a traumatic myiasis with a very high percentage of infested animals found only in a farm (10.5%). Wounds were mainly localized on the vulva and prepuce. Infested animals were restless, anxious, and reluctant to graze. None of the 10 goats in one infested flock had wounds, whereas a shepherd dog from another flock presented a wound on the ear. All the larvae and adults reared from them in the laboratory were identified as Wohlfahrtia magnifica (Schiner, 1862) (Diptera, Sarcophagidae). The cases presented here are the first clinical cases of wohlfahrtiosis in sheep and dogs reported in Italy, and indicate that this myiasis is endemic in this country. A wider epidemiological investigation on the prevalence, incidence and seasonality of W. magnifica infestation of Italian W. magnifica population/s would be useful to understand its geographical provenience and the likely risk for its spreading throughout Italy and other non-endemic areas.     

Cyromazine pour-on for the prevention of cutaneous myiasis of sheep

The results of trials on eight farms to assess the efficacy of two pour-on formulations containing cyromazine for the prevention of cutaneous myiasis of sheep are presented; data from trials on sheep with larval implants and on sheep kept in cages with adult flies are also reported. The incidence of cutaneous myiasis was reduced by between 87 per cent and 100 per cent for eight weeks when a formulation containing 6 per cent w/v cyromazine was used at an application rate of 60 to 85 mg of active ingredient/kg bodyweight. When a formulation containing 10 per cent w/v was used at an application rate of 50 to 100 mg/kg, the incidence of the condition was reduced by between 90 per cent and 100 per cent for eight weeks. Studies of sheep with larval implants, using the formulation containing 10 per cent w/v cyromazine at 50, 100 and 150 mg/kg bodyweight gave variable results with some animals at each dose rate having lost protection by the seventh week. When sheep were treated with the formulation containing 10 per cent w/v cyromazine at 50 or 100 mg/kg and exposed to adult flies in fly-proof cages they were completely protected for nine and eight weeks, respectively.     

Wohlfahrtia magnifica (Schiner, 1862) Diptera: Sacrophagidae) causing a vaginal myiasis in domesticated two-humped camels in the Mongolian People's republic]

Wohlfahrtia magnifica (Schiner, 1862) [Diptera: Sarcophagidae] was established as the causal agent of a vaginal myiasis in female camels in the Mongolian Democratic Republic. Changes of the genitals occur nearly the beginning of June, 4-6 weeks after foaling, a spontaneous recovery is seen at the beginning of October. Clinical signs of the vaginal myiasis and morphology of the three stages of larvae are described in detail.     

Differentiation by polymerase chain reaction - restriction fragment length polymorphism of some Oestridae larvae causing myiasis

The cytochrome oxidase I (COI) gene of the most wide-spread Italian species of Oestridae larvae causing myiasis (Gasterophilus spp., Hypoderma bovis, Hypoderma lineatum, Oestrus ovis and Przhevalskiana silenus) was amplified by polymerase chain reaction (PCR) using conserved primers. Restriction fragment length polymorphism (RFLP) of amplicons was also carried out and their restriction profiles compared. A clear genetic difference between the Oestridae larvae examined was demonstrated by using Taq I, Hinf I, Rsa I and Hpa II enzymes. No intra-specific variation in RFLPs was detected between the two species of Hypoderma. The results highlight the taxonomic and phylogenetic relationships among larvae belonging to the different subfamilies, and thus offer additional diagnostic and epidemiological instruments.     

Retrospective study of Old World screwworm fly (Chrysomya bezziana) myiasis in 59 dogs in Hong Kong over a one year period

This retrospective study examined the case records of Old World screw-worm fly myiasis in dogs in Hong Kong's New Territories. Myiasis due to OWSWF was identified and treated in 59 dogs at our clinic over a period of 1 year. Signalment, causes of initial wound, and treatments implemented, are reported. All cases recovered from myiasis with a combination of larvae removal and wound debridement, antibiotics, and topical and systemic insecticides. Whilst this parasite is currently exotic to Australia, much of the country is environmentally suitable (tropical and subtropical) for establishment of OWSWF.     

Cuterebrid myiasis (Diptera: Oestridae) in captive ring-tailed lemurs (Lemur catta) at a South Carolina zoo

In September 2008, two ring-tailed lemurs (Lemur catta), comprising a mother-daughter pair, at the Greenville Zoo, Greenville, South Carolina, USA, were diagnosed with cuterebrid myiasis (Diptera: Oestridae) subsequent to sudden death of the adult lemur. On necropsy, a single bot warble was discovered in the subcutis of the axillary region. Histopathology revealed a severe eosinophilic bronchopneumonia. The juvenile lemur was inspected and found to have warbles on three separate dates in late September. One representative bot fly larva was identified as a Cuterebra sp. that normally infests lagomorphs in the southeastern United States. Cuterebrid myiasis is rarely reported in lemurs and has not been previously associated with pneumonia or death in these animals.     

World Association for the Advancement of Veterinary Parasitology (W.A.A.V.P.) guidelines for evaluating the efficacy of ectoparasiticides against myiasis causing parasites on ruminants

These guidelines have been prepared to assist in the planning, conduct and interpretation of studies for the assessment of efficacy of ectoparasiticides against the myiasis causing parasites of ruminants. These guidelines specifically focus on larvicidal efficacy against myiasis causing flies. Information is provided on the selection of animals, dose determination and dose confirmation studies, field studies, record keeping and result interpretation. These guidelines advocate the use of pen facilities for dose determination and dose confirmation studies for defining therapeutic and persistent efficacy. These guidelines are also intended to assist investigators on how to conduct specific experiments, to provide specific information for registration authorities involved in the decision-making process, to assist in the approval and registration of new ectoparasiticides, and to facilitate the world-wide adoption of standard procedures.     

Persistent activity of doramectin and ivermectin in the prevention of cutaneous myiasis in cattle experimentally infested with Cochliomyia hominivorax

A study was conducted to evaluate the activity of a single administration of doramectin or ivermectin against severe, induced infestations of Cochliomyia hominivorax. Twenty-four Holstein bull calves were allocated to four groups of six animals each and treated either with saline, doramectin 1%, or either one of two formulations of ivermectin 1% at a dose rate of 200 microg/kg. On Day 12 after treatment, each calf was anesthetized and two wounds were created on the left side of the shoulder and rump of each calf and 2 h later, each wound was implanted with 100 newly hatched larvae of C. hominivorax. On Day 15 after treatment, the procedure was repeated on the right side of each calf. Wounds were examined daily for 5 days and evidence of live larvae was recorded. Doramectin provided reduction in myiasis of 90.9 and 83.3% at 12 and 15 days after treatment, respectively, compared to the saline control treatment (P < 0.0001). In contrast, there were no significant differences in the number of calves with myiasis between those treated with either of the ivermectin formulations and the saline control.     

Traumatic myiasis of horses caused by Wohlfahrtia magnifica.

A survey was carried out in three stud farms with grazing animals, in order to gather data on the prevalence and clinical manifestation of, and the fly species involved in, traumatic myiasis of horses in Hungary. This parasitic disease was recorded in each farm. On the whole, 9.0% (14) of the inspected horses were infested with fly larvae. The affected horses had one infested lesion only, located at the mucosa of the vulva or the vaginal vestibule. The clinical symptoms depended on the age of infestation. Wohlfahrtia magnifica (Diptera: Sarcophagidae) was the only myiasis-causing fly species identified. It was assumed that unknown volatile chemicals might be responsible for the attraction of gravid females to the undamaged vulvar region. These odours are supposed to be produced during different physiological and/or pathological events associated with oestrus, prolonged puerperal period or inflammation of tissues. Daily inspection of grazing horses and early treatment of the affected areas are needed to avert significant damage to the infested horses.     

First reported case of Hypoderma diana Brauer, 1985 (Diptera: Oestridae)-associated myiasis in a horse in Germany

A massive infestation with warble fly larvae was observed in a mare in Lower Saxony, Germany. From a herd of 20 horses, only a single mare accidently escaped the routine treatment with macrocyclic lactone in autumn and showed the myiasis infestation next year in January. Eighteen subcutaneous nodules were found on the back (n = 2), ribs (n = 3), flank (n = 5) and croup (n = 8). Deer, the specific hosts of the warble fly Hypoderma diana, was abundant on this farm and some other risk factors for the hypodermiosis are discussed herein. This is the first report of myiasis caused by H. diana in horses in Germany. This massive warble fly infestation in a horse in Germany reported here is important to alert equine health professionals concerning the prevention of this disease in the routine parasite control programme.     

Residues of spinosad in the tissues of sheep after aerosol treatment of blowfly myiasis

OBJECTIVE: To measure the residues of spinosad and chlorhexidine in the tissues of sheep after treatment of blowfly strike. PROCEDURE: Fourteen sheep with natural myiasis and 12 with artificial infestations of Lucilia cuprina larvae had the wool removed over their infestations and were treated with an aerosol wound dressing containing spinosad and chlorhexidine. Sheep were killed up to 14 days after treatment and residues of the chemicals measured in tissues. RESULTS: Chlorhexidine was not detected in any tissue. Residues of spinosad were highest in fat, lowest in muscle and intermediate in liver and kidney. The highest residue detected was 0.2 mg/kg spinosad in perirenal fat 7 days after generous treatment of a sheep with a large fly strike. Residues of spinosad in fat peaked 3 to 7 days after treatment and 1 to 3 days after treatment in liver and kidney. CONCLUSION: These studies present a realistic worst-case in struck sheep and at the highest dose studied, equivalent to 5.8 mg spinosad per kg body weight, the maximum residue detected of 0.2 mg/kg in peri-renal fat was 20% of the Australian maximum residue limit. Muscle, liver and kidney residues of spinosad were also below the Australian maximum residue limits at all times.     

Cochliomyia hominivorax myiasis in a colony of stray cats (Felis catus Linnaeus, 1758) in Rio de Janeiro, RJ

Cochliomyia hominivorax infestation in domestic cats of an urban colony in the city of Rio de Janeiro is described. The overall prevalence over the period 2001-2005 was 12.5%. Only adult cats were found infested and among these, most cases were observed in males (28%) (p < or = 0.05). The most frequently infested areas of the cats' bodies were the face and nape of the neck. Most lesions were found on the front part of the body of adult males (80%), suggesting that myiasis occur in consequence of competitive fighting wounds.     

Traditional remedies used for the treatment of cattle wounds and myiasis in Amatola Basin, Eastern Cape Province, South Africa

A questionnaire survey was carried out to document traditional remedies used in the treatment of cattle wounds and myiasis in Amatola Basin. Eighty-three cattle farmers from nine villages were interviewed. The majority of respondents (67.9%) use traditional remedies for treatment of these conditions. However, 25.9% of them use a combination of traditional remedies with conventional medicines. The survey revealed that 13 medicinal plants belonging to 11 families were used. Aloe ferox, Prunus persica and Phytolacca heptandra were, however, the most commonly used. Leaves are the most frequently used plant part, often prepared as an infusion. Other non-plant remedies used include disinfectants, antiseptics as well as diesel and petrol. Manual removal of maggots from wounds was also practise and treatment is usually continued until the wound heals.     

Evaluation of the prophylactic effect and curative efficacy of fipronil 1% pour on (Topline) on post-castration scrotal myiasis caused by Cochliomyia hominivorax in cattle

A field trial was carried out during a summer-fall period on a commercial beef cattle farm in Minas Gerais State, located in the Southeast of Brazil. In order to evaluate the prophylactic effect and the curative efficacy of fipronil in a 1% solution, 200 Zebu crossbred bulls, with ages varying from 20 to 30 months and weights from 233 to 362 kg, were selected. The bulls were assigned by ranked pair to an untreated control group (A) or to a treated group (B), resulting in 100 animals per group. All experimental animals were surgically castrated on day 0, following routine procedures. After castration all animals in the group B were treated with 10 mg/kg bw of a 1% fipronil solution, topically on the dorsal mid-line. The wounds were individually inspected on days: 2, 4, 7, 10, 14, 17, 21, 28 and 35. After castration the animals were naturally exposed to Cochliomyia hominivorax and remained in the same pasture throughout the trial. Among the animals in the control group, 83 were observed to harbor C. hominivorax eggs, with a total of 97 ovipositions, and among those 73 animals had active myiasis. In group B (fipronil 1%), 66 animals showed C. hominivorax eggs, with 92 ovipositions and five animals with active myiasis. Most ovipositions and active myiasis were detected until seven days post-castration for both groups. Wound parasite infestation evidenced bleeding, serous purulent exudation and presence of active C. hominivorax larvae. Treatment with fipronil 1% had a prophylactic effect on scrotal wounds against the development of C. hominivorax larvae in more than 95% of the treated animals for up to 17 days after castration. The treatment showed partial protection of 66% and 50% on days 21 and 28 post-treatment (pt), respectively. Three animals from the control group and one from the treated group showed active screwworms on day 21 pt, and one animal from the treated group and two from the control group also presented C. hominivorax larvae on scrotal wounds on day 28 pt. By the end of the observation period (day 35 pt), the castration wound had healed in all animals. All experimental animals presenting scrotal wounds infested with C. hominivorax larvae were treated with a 1% pour-on formulation of fipronil, on the same day that infestation was observed. Active C. hominivorax larvae were not seen during the monitoring period immediately after treatment. The curative efficacy of fipronil 1% against C. hominivorax larvae infestation in castration wounds was 100%.     

Nasal myiasis in a dog due to Oestrus ovis (Diptera: Oestridae)

Abstract

Extract

Oestrus ovis or nasal bot-fly, has larvae that are deposited as the first instar and develop in the nasal fossae and cranial sinuses of sheep, goats and some wild ruminants (Zumpt, 1965 Zumpt, E. 1965. Myiasisin Man and Animalsin the Old World London: Butterworths,.  [Google Scholar]). Once the larvae have matured they are sneezed out and pupariate in the soil. Occasionally, humans are affected by ocular myiasis (ophthalmomyiasis) and more rarely, nasal myiasis (Macdonald et al, 1999 Macdonald, PJ, Chan, C, Dickson, J, Jean-Louis, F and Heath, A. 1999. Ophthalmomyiasis and nasal myiasis in New Zealand: a case series. New Zealand Medical Journal, 112: 445–457. [PubMed], [Web of Science ®] , [Google Scholar]). The presence of O. ovis in dogs is also a rare occurrence (Zumpt, 1965 Zumpt, E. 1965. Myiasisin Man and Animalsin the Old World London: Butterworths,.  [Google Scholar]) and in such non-typical hosts it is usual for development of the larvae to proceed no further than the first instar. Exceptions have been noted in dogs, where third instar larvae were expelled (Lucientes et al, 1997 Lucientes, J, Ferrer-Dufol, M, Andres, MJ, Peribañez, MA, Gracia-Salinas, MJ and Castillo, JA. 1997. Canine myiasis by sheep bot fly (Diptera: Oestridae). Journal of Medical Entomology, 34: 242–243.  [Google Scholar]) or recovered from the nasal cavity at necropsy (Luján et al, 1998 Luján, L, Vázquez, J, Lucientes, J, Pañero, JA and Varea, R. 1998. Nasal myiasis due to Oestrus ovis infestation in a dog. Veterinary Record, 142: 282–283.  [Google Scholar]).     

Observations on the New World screwworm fly in Libya and the risk of its entrance into Egypt.

Data on traumatic myiasis caused by Cochliomyia hominivorax in Libya were reported from August 1988 until February 1989. A total of 468 cases of screwworm myiasis were recorded in seven species of livestock and 229 humans, mainly children, were also found to be infested. Cattle and sheep were the most common hosts in livestock. In cattle, the principal infestation site was the umbilicus of neonates; in sheep, it was mainly the fatty tail. Animal myiasis reached its peak in October and November, but disappeared abruptly in winter on the onset of cold weather. Screwworm distribution was confined to the northwest of Libya. The potential dispersion of the fly from this area and the possibility of infestation of other countries, particularly Egypt, are discussed. Food and Agriculture Organization (FAO) efforts to confront the New World screwworm problem in Africa are mentioned.     

The relationship between nasal myiasis and the prevalence of enzootic nasal tumours and the effects of treatment of Oestrus ovis and milk production in dairy ewes of Roquefort cheese area

Infection by Oestrus ovis is common in Lacaune dairy ewes of Roquefort cheese area (Aveyron, France). It is believed by local breeders that there is a close relationship between nasal myiasis and the incidence of enzootic nasal tumour. In order to check these anecdotal reports, a serological survey was done on 658 breeding ewes before turn-out and 897 breeding and primiparous (hoggets) ewes at the end of the grazing season. By the time of sampling, it was clear whether the sheep were infected at the end of the winter or had been re-infected over summer.In April and September, 40.7 and 26.3%, respectively, were free of O. ovis infection, indicating that the autumn treatment was not completely effective and that O. ovis adult flies were circulating during the summer in many flocks. There were no differences in the incidence of adenocarcinoma between the groups indicating that there is no relationship between O. ovis infection and the presence of the cancer.Differences in milk production between the three groups were not statistically significant (Anova test P>0.05). In flocks where 1-5% of the ewes were infected or in non-infected flocks, ewes produced 3.6 and 8.56%, respectively, more milk than ewes from flocks where more than 5% of animals were infected. For primiparous ewes, the differences were of 8.5 and 12.24%.