The efficacy of fluazuron in the management of blowfly strike in sheep.

The blowflies Lucilia spp. and Chryomya spp. feature prominently as a leading cause of myiasis and production losses in sheep in South Africa. With chemical means of preventing and treating blowfly strike being a common manner of control, new molecules or formulations effective against blowfly strike are needed as resistance becomes more of a problem. For this study we evaluated the potential of topical application of fluazuron on sheep as an additional means to control blowflies. When pure fluazuron was applied to raw meat at the recommended dose for cattle, significant effects on adult fly development were observed. However when applied topically to post-mortally collected sheep pelts at the same dose rate, no significant effects were observed on larval repellence or larval development with fly development progressing as expected. A subsequent pharmacokinetic study showed virtually no systemic absorption together with significant wool binding. Despite demonstrating that fluazuron was effective against blowfly larvae, wool binding of the molecule preclude its use.

In vitro test for the evaluation of the efficacy of topical products for the control of Cochliomyia hominivorax larvae.

Cochliomyia hominivorax larvae cause myiasis in animals and humans. To register a commercial product to control this dipteran is necessary to experiment on animals. The in vitro test was standardized to evaluate the larvicidal efficacy of commercial topical products. Five formulations were analysed in vitro and in vivo. For the in vitro test, a colony was formed and three replicates (n = 200) of each larval stage (L1, L2 and L3) were treated. The viability of the larvae was evaluated after 5 and 30 min, and at 1, 2, 6, 12, 24, 48, 60 and 72 h post-treatment (HPT). For the in vivo test, 30 bovines divided into six groups were castrated to achieve natural infestation with C. hominivorax. Animals in the treated groups received the product. Myiasis and efficacy were evaluated 12, 24, 36, 48, 60 and 72 HPT. Four formulations tested in the in vitro test achieved 100% efficacy at 24 HPT. In the in vivo experiment only one achieved 100% efficacy at 24 HPT. However, all products achieved the maximum efficacy by the end of study. The in vitro test developed here could be adopted to evaluate the efficacy of topical products for the control of C. hominivorax larvae.

Internal morphological changes during metamorphosis in the sheep nasal bot fly, Oestrus ovis.

During the larval stage, oestrid flies (Diptera: Oestridae) are obligate parasites, whereas during the adult stage they are free-living and do not feed. Like other cyclorrhaphous flies, oestrids undergo metamorphosis inside an opaque puparium, formed by the contracted and hardened cuticle of the third-instar larva. The present study documents the internal morphological changes taking place during metamorphosis of the sheep nasal bot fly, Oestrus ovis L., using non-invasive, micro-CT-based virtual histology and provides quantitative data of volumetric changes in specific organs. Virtual histological sections allowed visualisation of the progression and completion of the apolyses, which delimit the different intra-puparial stages, and the connection to the tracheal system of a large gas bubble, which plays an essential role during early metamorphosis. Overall, our results show that the sequence of morphological and volumetric changes in tissues and organs is similar to those found in other cyclorrhaphous flies, but they also reveal developmental differences that result in an adult vestigial digestive tract. Future studies could develop non-invasive, reliable methods for aging the intra-puparial forms of different oestrid species of veterinary importance, based on both qualitative and quantitative markers, thus improving our knowledge of their development and the efficiency of control strategies.

Travelers' tropical skin diseases: Challenges and interventions.

Tropical regions receive a significant part of the traveling population. It is very important that health professionals are familiar with the main tropical skin diseases and able to advice patients appropriately. This article reviews the main tropical diseases of travelers, with an emphasis on diagnosis, management, and prevention. Among others, cutaneous larva migrans, myiasis, tungiasis, Chagas disease, Dengue fever, African trypanosomiasis, filariasis, and leishmaniasis are discussed. Increasing awareness among travelers and health care professionals can help reduce morbidity and mortality. Continued research on new drugs and vaccines is needed to reduce the risks of tropical diseases.

Tissue damage and cytotoxic effects of Tagetes minuta essential oil against Lucilia cuprina.

The blowfly Lucilia cuprina has great medico-sanitary and veterinary importance due to the ability of its larval form to develop in decaying organic matter, parasitizing vertebrates. Fly eradication is challenging and the essential oil (EO) of Tagetes minuta (TMEO) have been reported to have therapeutic properties. This study aimed to determine the activity of EO from the aerial parts of T. minuta against third instar larvae (L3) of L. cuprina. Groups of 20 L3 were placed on filter paper, which were impregnated with varying concentrations (0.19; 0.39; 0.79; 1.59; 2.38; 3.18; 4.77; and 6.36 µL/cm2) of TMEO solubilized in acetone, ethanol or Tween 20. Histological tissue damage of TMEO was measured in L3 after 24, 48 and 96 h of exposure. Dihydrotagetone (67.64%), trans-ocimene (16.23%), trans-tagetone (10.14%) and verbenone (2.98%) were obtained as major compounds of TMEO. Lethal concentrations of 50%, 24 and 48 h after TMEO exposure were 1.02 and 0.73 µL/cm2 for acetone; 3.37 and 1.75 µL/cm2 for ethanol; and 7.46 and 6.11 µL/cm2 for Tween 20, respectively. TMEO had a significant L3 mortality of 96.6% in acetone, 48 h after contact. Cuticle abnormalities were observed, as well as the loss of digestive tract architecture and vacuolization in fat bodies. TMEO presented time and concentration-dependent effects against L. cuprina. As our study demonstrated a strong insecticide activity of TMEO, we consider that it could be developed into an ecofriendly product against L. cuprina.

Response of Lucilia sericata (Diptera: Calliphoridae) to Screwworm Oviposition Attractant.

The sheep blowfly, Lucilia sericata Meigen (Diptera: Calliphoridae), causes sheep myiasis in various parts of the world. Female flies are attracted to sheep following various olfactory cues emanating from the sheep's body, and oviposit on suitable substrates on sheep ultimately causing myiasis. Earlier workers attempted to reduce fly population in the field, with some success, using traps baited with various attractants. This research was conducted to determine if L. sericata would respond to a recently developed synthetic attractant that has attracted gravid screwworms, Cochliomyia hominivorax Coquerel, and stimulated them to oviposit. Results of the laboratory bioassays demonstrated that gravid females L. sericata were attracted to substrates treated with the synthetic screwworm attractant composed of five compounds--dimethyl disulfide, dimethyl trisulfide, phenol, p-cresol, and indole. Tests with various combinations of these compounds suggest that the sulfur compounds and indole are the most important compounds to elicit attraction and stimulate oviposition, while phenol and p-cresol may have minor roles. Semiochemical baits based on these compounds may be useful in the field to trap gravid L. sericata.

[Nosocomial myiasis in Latin America and the Caribbean: an overlooked reality?]. / Miasis nosocomiales en América Latina y el Caribe: ¿una realidad ignorada?

Nosocomial myiasis is an infestation by fly larvae that occurs while a patient is hospitalized. To analyze the available information on nosocomial myiasis in Latin America and the Caribbean, a search was done for cases published in the last 52 years. Nine clinical cases were found for Brazil, Costa Rica, French Guiana, Honduras, and Jamaica. Two other publications mention 139 cases in El Salvador and some 32 in Colombia, respectively. The patients and environments described presented conditions that predispose to this type of infestation. Compulsory notification is not usually required for nosocomial myiasis in Latin America and the Caribbean, meaning that there is probably considerable underreporting. Awareness needs to be raised and registry improved of myiasis in the region to aid in adoption of better prevention measures, which will benefit patient care during hospitalization.

Field efficacy of minidosed pour-on ivermectin and eprinomectin against goat warble fly infestation by Przhevalskiana silenus.

The efficacy of minidose of pour-on ivermectin and eprinomectin formulations against first instar larvae of Przhevalskiana silenus was observed in naturally infested goats in the Jammu region, North India. The study was performed in mid August 2011. A total of 280 goats were randomly divided in to 7 groups of 40 each. Goats of the first three groups were treated with pour-on ivermectin at dosage of 2, 5, and 200 µg/kg body weight, respectively, whereas animals of the fourth to sixth groups were treated with pour-on eprinomectin at 25, 50, and 500 µg/kg body weight, respectively. Group VII animals were kept as untreated control. The results indicated that no warbles were recorded between December 2011 and March 2012 on back of animals treated with pour-on preparations of ivermectin at dosage of 5 and 200 µg/kg body weight, respectively, and eprinomectin at dosage of 50 and 500 µg/kg body weight, respectively. Thus, it is concluded that administration of minidose of pour-on ivermectin (5 µg/kg body weight) and eprinomectin (50 µg/kg body weight) is cost effective and so can be used for warble fly control campaign in Jammu region.

Human myiasis in Fars Province, Iran.

We evaluated the prevalence and consequences of human myiasis among people involved in animal husbandry and butchers among 6 counties in Fars Province, Iran using a descriptive cross sectional survey. A semi-structured questionnaire was used to evaluate knowledge, community perceptions and practices. Three hundred two herders shepherds and butchers were included in the study. Eighty-eight point three percent of subjects had experienced myiasis during their job experiences. Seventy-one point five percent had become infected in barns. Pharyngeal myiasis was reported by 87% of subjects. The most likely cause of myiasis in subjects was the sheep botfly, Oestrus ovis (Diptera: Oestridae). Age and job experiences did not have an effect on the knowledge and practice regarding myiasis of subjects. Academic educational level had no significant effect on knowledge but did have a significant effect on practices. A myiasis education program needs to be created to better control and prevent this problem.

Number of rainy days in a week influencing screwworm navel myiasis in beef calves and efficacies of injectable and topical antiparasitics.

Rainfall incidence as a risk factor for umbilical myiasis by Cochliomyia hominivorax in newborn beef cattle and the preventive and curative efficacies of injectable and topical products against its larvae were evaluated. The prevalence of navel myiasis did not differ between sex, however, it did differ between seasons of the year, independent of animal sex, with it being higher in the rainy season than in the dry season for both sexes (males 64.6%, females 62.1%). During the rainy season, rains occurred intermittently and the number of rainy days in a week had a direct influence on prevalence, with an increase (≥87%) in the number of calves with navel myiasis caused by C. hominivorax. When it rained intermittently for four, five and six days in a week during the rainy season, calves had ≈12, 24 and 11 times greater chances, respectively, of having navel myiasis compared to a week without rain during the rainy season. The injectable products did not reach preventive efficacies higher than 35%, while all treatments of topic products reached 100% preventive efficacy at 10 days post-treatment. Only the formulations with 30% dichlorfenthion and 0.32% fipronil achieved 100% curative efficacy. The results reinforce the need for intensified inspection and healing of the umbilicus during the rainy season, mainly during rainier weeks. Furthermore, topical formulations may be a better alternative as a preventive treatment than avermectin formulations. However, the curative efficacy of the topical product containing dichlorvos did not demonstrate a relationship with preventive efficacy for newborn calves.

A survey of the prevalence of blowfly strike and the control measures used in the Rûens area of the Western Cape Province of South Africa.

Blowfly strike and the methods used to combat blowfly strike were recorded on 33 properties in the Rûens area of South Africa during 2003/2004. Data were recorded on Merino and Dohne Merino hoggets (n = 4951) with at least 3 months' wool growth. The following data were captured: presence or absence of strike, site of the strike (body or breech), presence or absence of dermatophilosis as well as subjective scores for wool quality and wool colour. Control measures recorded include: chemical treatment (preventative and spot treatment), crutching, mulesing and the use of the Lucitrap system. Blowfly strike was not significantly influenced by gender or breed. Hoggets suffering from dermatophilosis were more likely to be struck, compared with contemporaries not suffering from the skin disorder (0.057 vs 0.027; P < 0.05). Merino hoggets generally had higher scores than their Dohne Merino contemporaries for wool quality (32.6 vs 27.4; P < 0.05) and wool colour (29.0 vs 27.2; P < 0.05). There was an indication that the Lucitrap system may have reduced flystrike, but the effect was not statistically significant (P = 0.19 for overall strikes and P = 0.12 for body strike). The Mules operation benefited overall flystrike (0.013 vs 0.110; P < 0.05); mainly through an effect on breech strike (0.010 vs 0.109; P < 0.05). The proportion of fly strikes increased with wool length, and declined with an increase in farm size in wool colour score. None of the ethically acceptable control measures assessed could substantially reduce blowfly strike on their own, and an integrated pest management programme was proposed.

Gingival Myiasis on Oral Squamous Cell Carcinoma in Turkey: A Case Report

Myiasis is a disease caused by tissue invasion of diptera larvae and eggs. Oral myiasis is mostly related to old age, poor oral hygiene, suppurative lesions, anatomical disorders and cancer cases. Oral squamous cell carcinoma (OSCC) is an important risk factor for myiasis. This report presents the case of an 82-year-old woman who presented with gingival myiasis developing on the background of OSSC. The patient was diagnosed with OSSC in the hospital. Myiasis larvae were identified and sent to the National Parasitology Reference Laboratory for identification. Thus, development of myiasis on OSCC background was shown in Turkey for the first time. Myiasis larvae have been identified as the 3rd phase of the larvae Sarcophaga sp. development (Diptera: Sarcophagidae). As a result, myiasis cases are sporadic in Turkey, and it can be avoided by controlling fly population and by paying attention to hygiene. Controlling myiasis is an important public health problem and should be considered in a single health concept, as it causes health problems in both humans and animals. The findings of this case will draw attention to the importance of dealing with myiasis factors, which is a public health problem.

Cutaneous myiasis in a geriatric patient.

Cutaneous myiasis in humans involving fly species endemic in Italy are uncommon and are not often present in the literature. In the present article we describe the case of cutaneous myiasis in a woman brought to the Emergency Department (ED) of the S. Croce e Carle General Hospital in Cuneo, northwest Italy. The patient was in precarious hygienic condition, and was suffering from localized ulcerated foot ulcers with significant inflammation extending up to the knee. Fly larvae, subsequently identified as Lucilia sericata (Meigen, 1826), were found in the lesions. The patient was admitted to the Department of Internal Medicine where she was treated with antibiotics and the lesions were medicated, resulting in full recovery.

Autocidal control of screwworms in North America.

The larva of the blowfly Cochliomyia hominivorax, also known as the screwworm, eats the living flesh of cattle and sheep and other warm-blooded animals. A program to eradicate the screwworm in the United States was initiated in the 1950's. The program was very effective until 1968, but severe screwworm outbreaks occurred in 1972 to 1976 and in 1978. Although the program has again been effective since 1979, the possibility of outbreaks recurring in the future has highlighted the need for a broader understanding of the pest. Studies of screwworm populations in the United Stated and Mexico indicate that much of the genetic diversity of this insect is distributed among sympatric non-interbreeding populations. A new approach may be required to retain the effectiveness of the control program and to prevent a serious outbreak from threatening the economic viability of the U.S. livestock industry.

Current status of the New World screwworm Cochliomyia hominivorax in Venezuela.

The geographical distribution and seasonality of the New World screwworm (NWS), Cochliomyia hominivorax Coquerel (Diptera: Calliphoridae), were monitored through the use of sentinel animals as part of a co-ordinated programme involving veterinarians and farmers, as well as undergraduate students and teachers from veterinary colleges in Venezuela. This surveillance activity made it possible to collect NWS egg masses or larvae from all 23 states in the country and to determine that the rainy season has a strong positive influence on the number of cases of myiasis caused by C. hominivorax in dogs. In addition, efforts were made to obtain the co-operation of the public health service in order to document the extent of human myiasis in the western-central region of Venezuela. Preliminary results revealed 241 cases over a 7-year period, with cases reported in infants as well as in elderly people. Larvae causing myiasis, other than C. hominivorax, were collected from primary myiasis in rabbit (Lucilia eximia [Wiedemann]), dog (an unidentified sarcophagid species), birds (Philornis sp.) and wild mice (Cuterebra sp.). The economic impact of NWS in Venezuela has not been calculated in terms of loss of milk and meat production, damage to hides or death of animals. Control costs (e.g. cost of larvicides) have been estimated at US$ 2 m per year. Control of myiasis in animals is achieved through the use of chemical compounds, mainly organophosphorus (OP) compounds, macrocyclic lactones and, more recently, a foamy spray based on spinosad. Concerns about insecticide resistance to OP compounds have been raised.

A sustained release gel formulation of doramectin for control of lone star ticks (Acari: Ixodidae) and horn flies (Diptera: Muscidae) on cattle.

A gel formulation formed by incorporating technical doramectin into a 10% hydroxypropyl methylcellulose aqueous solution was used to subcutaneously inject steers at varying dosages. Doramectin serum concentration of steers receiving 600 microg (AI)/kg body weight declined from 21.9 ppb at 0.5 wk to below detectable at 8 wk postinjection. The 1,200 microg (AI)/kg injection resulted in serum concentrations of 29.1 ppb at 0.5 wk and declined to 0.5 ppb at 8 wk postinjection. Both the 600 and 1,200 microg (AI)/kg injections provided 100% inhibition of index of fecundity (IF) in adult lone star ticks, Amblyomma americanum L. (Acari: Ixodidae) through week 8, after which inhibition declined to 79.4 and 45.3%, respectively, during the 12th week posttreatment. For steers treated at 600 microg (AI)/kg, mortality of adult horn flies, Hematobia irritans L. (Diptera: Muscidae), declined from 16.9% during week 2 to 3.1% during week 7 postinjection. The blood from steers treated at 1,200 microg (AI)/kg resulted in a similar decline in mortality of blood fed adult horn flies from 29.4% during week 1 to 4.0% during week 7. The 600 microg (AI)/kg treatment provided complete control of larval horn flies in the manure for 9 wk, whereas the 1,200 microg (AI)/kg injection gave complete control for 14 wk posttreatment. The doramectin gel formulation provided long-lasting delivery of doramectin to cattle and extended control of lone star ticks and larval horn flies. Such a simple and inexpensive formulation could be useful in tick eradication programs by reducing the frequency of gathering cattle.

Strategic use of crutching and dicyclanil to protect unmulesed sheep against breech strike.

OBJECTIVE: To test strategies for the application of dicyclanil and mid-season crutching to maximise protection of unmulesed sheep against breech strike. PROCEDURE: Three hundred and eighty unmulesed Merino weaners were randomly allocated to four groups either left untreated or treated by different strategies with 50 g/L dicyclanil. Treatments included breech treatment alone and breech plus body treatment, with two application times, immediately after shearing and 6 weeks after crutching or shearing. To assess protection, larval implants with newly hatched Lucilia cuprina larvae were applied to 10 different sheep from each group at 3, 4, 5 and 6 months after crutching and shearing and assessed for the development of strike at 48 hours. The concentration of dicyclanil was measured in wool samples clipped from the breeches of the test sheep. RESULTS: All dicyclanil treatments gave significant reduction in strike in comparison to controls up until 4 months after crutching but protection in the sheep treated immediately after shearing had waned at 5 months. Treating at 6 weeks after crutching provided significant reduction (P < 0.05) in strike for 6 months. Results for strike incidence immediately after shearing and concentration of dicyclanil in the breech wool also suggested improvements in protection by delaying treatment for 6 weeks. CONCLUSION: In most environments it should be possible to protect unmulesed sheep against breech strike with a carefully planned integrated control program incorporating strategically timed crutching, shearing and dicyclanil application. Delaying treatment with dicyclanil to at least 6 weeks after shearing or crutching increased the protection provided in comparison to treatment immediately after shearing.

Effect of the non-steroidal anti-inflammatory drug, carprofen, on weaned sheep following non-surgical mulesing by intradermal injection of cetrimide.

OBJECTIVE: To assess in weaned lambs the palliative effects of the non-steroidal anti-inflammatory drug, carprofen, following intradermal injection of cetrimide to induce non-surgical mulesing. PROCEDURES: We allocated 40 weaned lambs (20-22 weeks old) to four groups of 10 animals: (1) control, 2) conventional surgical mules, (3) intradermal treatment and (4) intradermal treatment + carprofen. Non-surgical mulesing was induced by intradermal injection of 4% (w/w) cetrimide + 3% (w/w) polyvinylpyrrolidone in water. In group 4, carprofen (4 mg/kg, SC) was administered 1 h before intradermal treatment. Five weaners, including an animal from each treatment, were run in each pen. Neutrophil to lymphocyte ratio, cortisol, beta-endorphin and haptoglobin levels and rectal temperature were monitored at least daily for the first 7 days after treatment, then weekly until day 28. Body weight was measured weekly and behaviour was measured every 15 min for 12 h on the day of treatment, then on days 1, 2, 4, 6, 12, 21 and 28 following treatment. RESULTS: The intradermal treatment resulted in high fever and elevated blood cortisol by 12 h. Rectal temperatures were significantly elevated until 5 days after treatment, cortisol was elevated until 3 days after treatment, haptoglobin for at least 7 days after treatment and the neutrophil to lymphocyte ratio until 4 days after treatment. Average daily gain was depressed in the week following treatment. Abnormal behaviours (hunched standing, stiff walking, pawing, lateral lying and lying intention) were increased on the day of treatment and for 6 days post treatment. Carprofen reduced the time spent in abnormal behaviours by approximately two-thirds but did not ameliorate the physiological responses to the intradermal treatment. CONCLUSIONS: In weaner sheep, carprofen ameliorated the behavioural responses, but was unable to provide relief from the intense and sustained physiological responses to non-surgical mulesing by intradermal injection of cetrimide. Systemic side-effects may be unavoidable with formulations based on quaternary ammonium compounds that are designed to reduce the risk of fly strike in sheep by remodelling breech tissue through induction of tissue necrosis.

Sheep blowfly strike: the cost of control in relation to risk.

Sheep blowfly strike (ovine cutaneous myiasis) is a widespread economic and welfare problem in sheep husbandry in many parts of the world. Strike incidence is determined by a complex interaction of fly abundance, host susceptibility and climate, combined with farmer husbandry and intervention strategies. Sheep farmers adopt a range of approaches to the type and timing of the management used for the control of blowfly strike, the rational basis for which is often not robust. Here a deterministic model, based on existing data relating to fly abundance, seasonal risk and strike incidence, is used to compare the variable costs associated with different strike management strategies. The model shows that not employing prophylactic treatment is the lowest cost strategy only where strike risk is low. In all other circumstances, prophylactic treatment incurs lower costs than not doing so, because the deaths associated with strike outweigh the costs of prophylactic treatment. Lamb treatment, in particular, has a substantial effect on strike and cost reduction, since lambs are the most abundant age-class of animals and are at the highest risk over the period when fly abundance is the greatest. Early-season treatment of ewes before shearing is also an important component of the lowest cost strategies, particularly when the blowfly season is extended. While the rational choice of the most appropriate strike management strategy is essential in the context of farm economics, welfare considerations lend added importance to treatment decisions that reduce strike incidence.

Occurrence of human urogenital myiasis due to neglected personal hygiene: a review.

Myiasis, the infestation of tissues or organs of vertebrate animals with dipteran larvae, is a common parasitic problem among domestic and wild mammals. The condition, which is also witnessed in humans, is relatively frequent in rural areas where people are in close contact with domestic animals. It is a subject of medical and veterinary importance, particularly in tropical and subtropical regions of the world. Human myiasis is generally encountered in open neglected wounds but can also affect body orifices with foetid discharge, such as the oral cavity, eyes, ears, anus and urogenital tract. Urogenital myiasis involves infestation of the urinary tract, as well as genital organs such as vaginal or penile orifices, with fly larvae. The condition is a rare among humans inhabiting developed countries but relatively more common in patients of low socio-economic status with poor hygienic conditions in developing countries. Damage varies from superficial to massive infestation, which may result in severe problems or even death of the individual. In the present study, the authors reviewed the past literature describing the cases of human urogenital myiasis, causative fly species and risk factors. The aim of the present article is to document the predisposing risk factors and provide guidelines for prevention and control of urogenital myiasis among humans. Besides poor genital hygienic conditions, other factors leading to urogenital myiasis include psychiatric disorders, the use of urinary catheters and uterine prolapse. Prevention of the condition is of utmost importance and involves the dressing and covering of open wounds, maintaining proper personal hygiene and control of fly populations.