Essential oil pharmaceuticals for killing ectoparasites on dogs.

BACKGROUND: External parasites, particularly ticks and fleas, are among the most common problems affecting dogs. Chemical medicines are commonly used to prevent and eliminate such external parasites, but their improper use can cause adverse reactions, and the toxins they contain may remain in the environment. OBJECTIVES: The objective of this study was to investigate the in vitro efficacy of Zanthoxylum limonella, citronella, clove, peppermint, and ginger essential oils against dog ticks and fleas and to test the sensitivity of dogs' skin to these essential oils. METHODS: The five essential oils were tested for in vitro efficacy against ticks and fleas, and the two most effective essential oils were then tested on the dogs' skin. RESULTS: The results revealed that these five essential oils at 16% concentrations effectively inhibited the spawning of female engorged ticks. In addition, all five essential oils had a strong ability to kill tick larvae at concentrations of 2% upward. Furthermore, 4% concentrations of the five essential oils quickly eliminated fleas, especially clove oil, which killed 100% of fleas within 1 h. A 50%, 90%, and 99% lethal concentration (LC50, LC90, and LC99) for the essential oils on tick larvae in 24 h were found to be low values. LC50, LC90, and LC99 for the essential oils on flea in 1 h was lowest values. Clove oil at 16% concentration was the most satisfactory essential oil for application on dogs' skin, with a low percentage of adverse effects. CONCLUSIONS: This study confirmed the effectiveness of essential oils for practical use as tick and flea repellents and eliminators. Essential-oil-based pharmaceutical can replace chemical pesticides and provide benefits for both consumers and the environment.

Immunity of fleas (Order Siphonaptera).

The immune response of arthropod vectors plays a key role in the spread and transmission of vector-borne diseases. Although fleas transmit several human pathogens (e.g., Bartonella henselae, Rickettsia felis, R. typhi, and Yersinia pestis), few studies have examined how these vectors respond to infection. In hematophagous arthropods, imbibed pathogens must survive the hostile environment of blood meal digestion, which includes proteolytic digestive enzymes, protease inhibitors and expression of genes associated with protection of epithelial linings. Additionally, insect epithelial cells exhibit local immune defense against ingested pathogens by producing antimicrobial peptides and reactive oxygen species. This review details these and other aspects of insect immunity as it relates to fleas, with an emphasis on the gut immune response to two blood-borne pathogens, R. typhi and Y. pestis.

Parasites of small Indian mongoose, Herpestes auropunctatus, on St. Kitts, West Indies.

Herpestes auropunctatus, the small Indian mongoose, is an invasive omnivore introduced to the Caribbean, including the island of St. Kitts over 150 years ago. It has played a role in changing native fauna and can carry zoonotic pathogens of public health importance. The aim of the current study was to estimate the prevalence of parasites harbored by mongooses. In total, 87 mongooses trapped from April to July 2015 were examined for parasites using (1) hair plucks (N = 79), ear swabs (N = 79), and general coat and skin examination (N = 87) for mites, ticks, lice, and fleas; (2) dissection of the trachea, bronchi, and lungs for lungworms and flukes (N = 76); (3) a double centrifugation fecal flotation method for parasites of the gastrointestinal tract (N = 75); and (4) PCR of heart homogenates for Toxoplasma gondii (N = 60). The only ectoparasite seen was Ctenocephalides felis (79.3%; 69/87), with most mongooses having > 10 fleas (based on a subjective assessment) but insufficient numbers to result in signs of pruritus or anemia. On fecal flotation, coccidial oocysts were found with a prevalence of 69.3% (52/75). Neither T. gondii, lungworm, nor fluke infections were detected with the methods used. The high number of C. felis-infested mongooses and the infestation level of the individual mongooses suggest that they could serve as a reservoir for these potential vectors of pathogens. No evidence was found to support that mongooses are a component of T. gondii cycles on St. Kitts, although this finding needs to be confirmed with a larger sample size from other geographic locations.

Preventive efficacy of NexGard Spectra® against Dipylidium caninum infection in dogs using a natural flea (Ctenocephalides felis) infestation model.

The efficacy of a monthly oral endectocide product, NexGard Spectra® (Merial), a combination of afoxolaner and milbemycin oxime, was evaluated in a flea (Ctenocephalides felis) challenge model for the prevention of Dipylidium caninum tapeworm infection in dogs. The efficacy of treatment with NexGard Spectra® was assessed in 10 dogs following weekly flea infestation with metacestode naturally infected fleas and compared with that in 10 untreated control dogs. The 100 fleas deposited weekly on each dog were not removed until Day 35, allowing enough time for their ingestion. The microscopical analysis of 30 fleas from the flea batches before each weekly challenge demonstrated that 10-33% of the fleas were infected by D. caninum cysticercoid larvae. The arithmetic mean flea count recorded was 47.7 for the 10 untreated dogs and 0 for the 10 treated dogs at Day 35. Based on the daily collection of expelled D. caninum proglottids by dogs during the 70 days of the study, 70% (7/10) of the control dogs and 0% (0/10) of the treated dogs were infected with D. caninum (p < 0.0031). Through its efficacy against fleas, NexGard Spectra® treatment provided indirect prevention of D. caninum infestation. No treatment-related adverse events were observed in dogs during this study.

Knock-down and speed of kill of a combination of fipronil and permethrin for the prevention of Ctenocephalides felis flea infestation in dogs.

BACKGROUND: A topical combination of fipronil + permethrin (Frontline Tri-Act/Frontect, Merial) has recently been developed to control fleas, ticks, mosquitoes, sandflies and stable flies on dogs. Two studies were conducted to assess its speed of kill and knock-down effect on Ctenocephalides felis fleas. The combination was compared to either fipronil alone or to a combination of permethrin, dinotefuran, and pyriproxyfen, METHODS: In each study, 18 dogs were randomly allocated to one of three groups: (Group 1: untreated dog; Group 2: treated once on D0 with the combination of fipronil and permethrin; Group 3: treated once on D0 either with fipronil alone (study 1) or with a combination of permethrin, dinetofuran and pyriproxyfen (study 2)). Each dog was infested with 100 unfed adult C. felis fleas on Days 2 (study 2), 7, 14, 21 and 28. Fleas were collected from dogs at 1 h and 12 h post- infestations (PI) (study 1) or at 2 h and 6 h PI (study 2) to assess efficacy and from collection pans underneath cages 1 h (study 1) or 5 min (study 2) PI to assess knock-down effect. RESULTS: All treated dogs had significantly (p ≤ 0.01) lower flea counts than untreated dogs at every time point in both studies. For a whole month, a significant knock-down effect against infesting fleas is obtained in five minutes PI with the combination of permethrin and fipronil. Complete efficacy (>95%) was achieved in 1 h (study 1) or 2 h (study 2) PI for 14 days and by 6 h PI for all challenges conducted throughout the month. Efficacy remains >85% at 2 h PI for the whole month. A significantly higher efficacy of the fipronil + permethrin combination compared to other treatments was demonstrated at the earliest time points for the month (1 h knock-down effect and insecticidal efficacy compared to fipronil alone; 5 min knock-down effect compared to the combination of permethrin + dinetofuran + pyriproxyfen). CONCLUSIONS: The rapid flea knock-down effect and speed of kill demonstrated by the spot on combination of fipronil + permethrin provide a reliable strategy against flea infestations in dogs.

Preventive efficacy of Frontline® Combo and Certifect® against Dipylidium caninum infestation of cats and dogs using a natural flea (Ctenocephalides felis) infestation model.

Two studies were performed to evaluate the effectiveness of two monthly topical anti-flea products for the prevention of Dipylidium caninum infestations in cats and dogs. A single treatment with Frontline(®) Combo spot-on for cats (fipronil-(S)-methoprene) and two successive monthly treatments of Certifect(®) for dogs (fipronil-amitraz-(S)-methoprene) were assessed for the prevention of D. caninum infestations following weekly challenges of treated cats or dogs with metacestode naturally-infected fleas. The rate of infestations using the model in cats versus dogs explains the choice of a 1-month trial in cats and a 2-month trial in dogs. The experimental flea-infection model resulted in a range of 22-53% of the fleas being infected by Dipylidium cysticercoids. The arithmetic mean flea counts recorded for the untreated cats ranged from 51.2 to 68. The geometric mean flea counts recorded for the Frontline Combo treated cats differed significantly (p < 0.05) from those of the untreated control cats on all assessment days. The arithmetic mean flea counts recorded for the untreated dogs ranged from 166.6 to 238.6. The geometric mean flea counts recorded for the Certifect treated dogs differed significantly (p < 0.001) from those of the untreated group on all assessment days. Frontline Combo treatment on cats provided ≥99.8% persistent anti-flea efficacy throughout the 30-day treatment period. In the dog study, the two Certifect treatments provided ≥97% persistent efficacy throughout the 60-day study. Based on the collection of expelled D. caninum proglottids by cats, 100% (6/6) of the control cats and 0% (0/6) of Frontline Combo treated cats were infested with D. caninum. Frontline Combo spot-on for cats was therefore 100% effective in preventing infection with D. caninum. In dogs, 7 out of the 8 control group dogs (87.5%) produced proglottids following infestation of infected fleas, whereas 0 out of 8 dogs (0%) in the treated group were infected. The infection rates of the two groups were significantly different. The percent effectiveness for the Certifect treatment group for the prevention of D. caninum infection was 100% during this 2-month trial. No treatment-related adverse events were observed in either cats or dogs during these studies.

Epidemiological prediction of the distribution of insects of medical significance: comparative distributions of fleas and sucking lice on the rat host Rattus norvegicus in Yunnan Province, China.

Determining the distribution patterns of ectoparasites is important for predicting the spread of vector-borne diseases. A simple epidemiological model was used to compare the distributions of two different taxa of ectoparasitic insects, sucking lice (Insecta: Siphonaptera) and fleas (Insecta: Anoplura), on the same rodent host, Rattus norvegicus Berkenhout (Rodentia: Muridae), in Yunnan Province, China. Correlations between mean abundance and prevalence were determined. Both fleas and sucking lice were aggregated on their hosts, and sucking lice showed a higher degree of aggregation than fleas. The prevalence of both fleas and sucking lice increased with log-transformed mean abundance and a highly linear correlation and modelling efficiency of predicted prevalence against observed prevalence were obtained. The results demonstrate that prevalence can be explained simply by mean abundance.

Prevalence of Rickettsia felis and the first identification of Bartonella henselae Fizz/CAL-1 in cat fleas (Siphonaptera: Pulicidae) from Taiwan.

Cat fleas (Ctenocephalides felis [Bouché]) are the primary ectoparasites of dog and cat populations. In this study, we report the monthly population dynamics of Rickettsia felis and Bartonella spp. (two zoonotic pathogens that can cause human disease) in cat fleas collected from dogs and cats in Taipei, Taiwan, from December 2006 to December 2007. Natural R. felis infection in individual cat fleas was assessed by polymerase chain reaction (PCR) using pRF-, ompB-, and gltA-specific primer pairs. Samples positive by PCR were confirmed with DNA sequencing. R. felis was detected in cat fleas year round, and the average infection rate was 21.4% (90 of 420) in 2007. Cat fleas also play an important role in the transmission of Bartonella between reservoirs and other mammalian hosts. In this study, we used primer pairs specific for the Bartonella gltA and rpoB genes to detect Bartonella infections. Of the 420 cat fleas tested, 38 were positive by PCR for Bartonella. Sequence similarities to Bartonella henselae, Bartonella clarridgeiae, and Bartonella koehlerae were observed in 6.2% (26 of 420), 2.1% (9 of 420), and 0.7% (3 of 420) of the fleas, respectively. Based on the pap31 gene sequence, several amplicons of the B. henselae detected in the cat fleas could be subgrouped into three strains: Fizz/CAL-1 (n = 18), Marseille (n = 5), and Houston-1 (n = 3). These results demonstrate that cat fleas infected with R. felis are endemic to Taiwan, and highlight the role of C. felis in Bartonella transmission between reservoirs and other mammal hosts and demonstrate the genetic variability of B. henselae in Taiwan.