Severe cat flea infestation of dairy calves in Brazil

Vector biology of the cat flea Ctenocephalides felis

Ctenocephalides felis, the cat flea, is among the most prevalent and widely dispersed vectors worldwide. Unfortunately, research on C. felis and associated pathogens (Bartonella and Rickettsia spp.) lags behind that of other vectors and vector-borne pathogens. Therefore, we aimed to review fundamental aspects of C. felis as a vector (behavior, epidemiology, phylogenetics, immunology, and microbiome composition) with an emphasis on key techniques and research avenues employed in other vector species. Future laboratory C. felis experimental infections with Bartonella, Rickettsia, and Wolbachia species/strains should examine the vector-pathogen interface utilizing contemporary visualization, transcriptomic, and gene-editing techniques. Further environmental sampling will inform the range and prevalence of C. felis and associated pathogens, improving the accuracy of vector and pathogen modeling to improve infection/infestation risk assessment and diagnostic recommendations.

Evidence that ectoparasites influence the hematological parameters of the host: a systematic review

Ectoparasites are important to the one health concept because their parasitism can result in the transmission of pathogens, allergic reactions, the release of toxins, morbidity, and even death of the host. Ectoparasites can affect host physiology, as reflected in immune defenses and body condition as well as hematological and biochemical parameters. Thus, evidence that ectoparasites influence host hematological parameters was systematically reviewed, and the methodological quality of these studies was analyzed. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines were followed, and the studies included were limited to those that evaluated changes in hematological tests in ectoparasite-infested and non-infested animals, and bias and methodological quality were evaluated using the Animal Research: Reporting of In Vivo Experiments guideline. Thirty-four studies were selected and information about the host, ectoparasite infestation, blood collection, and analysis was collected and compared whenever possible. In this review, the presence of ectoparasites influenced both the red series and the white series of hematological parameters. Among the main parameters analyzed, hematocrit, red blood cells, hemoglobin, and lymphocytes showed reductions, probably due to ectoparasite blood-feeding, while including eosinophils, neutrophils, and basophils increased in infested animals due to the host immune response. However, methodologic improvements are needed to reduce the risk of bias, enhance the reproducibility of such studies, and ensure results aligned with the mechanisms that act in the ectoparasite-host relationship.

Potential Effects of Environmental Conditions on Prairie Dog Flea Development and Implications for Sylvatic Plague Epizootics

Fleas are common ectoparasites of vertebrates worldwide and vectors of many pathogens causing disease, such as sylvatic plague in prairie dog colonies. Development of fleas is regulated by environmental conditions, especially temperature and relative humidity. Development rates are typically slower at low temperatures and faster at high temperatures, which are bounded by lower and upper thresholds where development is reduced. Prairie dogs and their associated fleas (mostly Oropsylla spp) live in burrows that moderate outside environmental conditions, remaining cooler in summer and warmer in winter. We found burrow microclimates were characterized by stable daily temperatures and high relative humidity, with temperatures increasing from spring through summer. We previously showed temperature increases corresponded with increasing off-host flea abundance. To evaluate how changes in temperature could affect future prairie dog flea development and abundance, we used development rates of O. montana (a species related to prairie dog fleas), determined how prairie dog burrow microclimates are affected by ambient weather, and combined these results to develop a predictive model. Our model predicts burrow temperatures and flea development rates will increase during the twenty-first century, potentially leading to higher flea abundance and an increased probability of plague epizootics if Y. pestis is present.

Parasitism of Nelore (Bos indicus) calf from northern Brazil by Ctenocephalides felis

Ctenocephalides felis is the most common hematophagous ectoparasite of domestic cats and dogs worldwide, causing allergic dermatitis, anemia, itching, discomfort, and it is responsible for the transmission of many pathogens. In cattle, parasitism is not common but occurs due to the high adaptability of this flea species. This study aimed to report infestation of a Nellore (Bos indicus) calf from Northern Brazil by C. felis and its clinical findings. A 45 kg male calf presented diarrhea, progressive emaciation after 50 days of birth, and flea infestation. Anemia was observed (4.11 × 10⁶/μL of erythrocytes; 20.48% of hematocrit). Coproparasitological examination and molecularly detection of Anaplasma spp. and Babesia spp. indicated negatively. Fleas were collected and taxonomically identified as C. felis. Clinical manifestations of this ectoparasite in cattle were unspecific; however, they can develop severe conditions, such as restlessness and weakness, accompanied by alopecia, emaciation, anemia, and edema of the lower limbs with intense itching and self-excoriation.

Deltamethrin Application on Pre-Weaned Calves Improves Feed Consumption, Stress and Fatigue Status under Heat Stress Conditions

Fly infestation remains a universal problem for dairy cattle herds, affecting the animals' health and welfare status. Pre-weaned dairy calves are significantly challenged by the direct and indirect consequences of severe fly infestation, heat-stress and their interaction, which contribute to a stressful and fatiguing environment. Among several physiological, behavioral, clinical and biochemical traits, serum cortisol (SC) and creatine kinase (CK) levels, as well as feed consumption can be used as valid indicators of potential stressful and fatiguing conditions and, therefore, can be efficiently used for stress analysis studies. Hence, the objective of the study was to assess the fly-repellency effect of deltamethrin on pre-weaned dairy calves exposed to heat stress conditions, as well as its association with SC, CK concentrations and feed consumption. Two commercial dairy cattle herds of the Holstein breed in Central Macedonia (Greece) were involved in the study during summer months and under heat stress conditions. Deltamethrin administration resulted in (i) a decreased fly population (100% Musca domestica) landing on pre-weaned dairy calves, (ii) a reduced SC (stress indicator) and CK (fatigue indicator) concentration, and (iii) an increased consumption of feedstuff in deltamethrin treated animals compared to the untreated ones.

What Is in a Cat Scratch? Growth of Bartonella henselae in a Biofilm

Bartonella henselae (B. henselae) is a gram-negative bacterium that causes cat scratch disease, bacteremia, and endocarditis, as well as other clinical presentations. B. henselae has been shown to form a biofilm in vitro that likely plays a role in the establishment and persistence of the bacterium in the host. Biofilms are also known to form in the cat flea vector; hence, the ability of this bacterium to form a biofilm has broad biological significance. The release of B. henselae from a biofilm niche appears to be important in disease persistence and relapse in the vertebrate host but also in transmission by the cat flea vector. It has been shown that the BadA adhesin of B. henselae is critical for adherence and biofilm formation. Thus, the upregulation of badA is important in initiating biofilm formation, and down-regulation is important in the release of the bacterium from the biofilm. We summarize the current knowledge of biofilm formation in Bartonella species and the role of BadA in biofilm formation. We discuss the evidence that defines possible mechanisms for the regulation of the genes required for biofilm formation. We further describe the regulation of those genes in the conditions that mimic both the arthropod vector and the mammalian host for B. henselae. The treatment for persistent B. henselae infection remains a challenge; hence, a better understanding of the mechanisms by which this bacterium persists in its host is critical to inform future efforts to develop drugs to treat such infections.

Ctenocephalides felis (cat flea) infestation in neonatal dairy calves managed with deltamethrin pour-on in Australia

Ctenocephalides felis infestations outbreak is documented as a welfare and production limiting disease in neonatal calves in eastern New South Wales, Australia. Due to the calves' discomfort, the first objective was to relieve the calves from the large burden of fleas. The affected neonatal 0-4 week old calves showed dull and quiet demeanour, with the geometric mean of body condition score (BCS) 2.67 (2-4) and geometric mean burden 41.51 (15-75) of fleas collected over 3 min. Deltamethrin pour-on (Arrest Easy-Dose, Virbac Animal Health, Australia) registered for treatment of lice and flies on cattle in Australia was evaluated for control effect of the cat flea (C. felis) on cattle. The fleas were identified morphologically as being C. felis which was confirmed by sequencing cytochrome c oxidase I gene (cox1). We report successful improvement of welfare and reduction of flea counts post application of pour-on deltamethrin on the property. In the absence of registered flea product for cattle in Australia, deltamethrin pour-on product is a suitable option, because of its registration for control of lice and flies on cattle.

Very severe tungiasis in Amerindians in the Amazon lowland of Colombia: A case series

Background

Tungiasis is a parasitic skin disease caused by penetrating female sand fleas. By nature, tungiasis is a self-limiting infection. However, in endemic settings re-infection is the rule and parasite load gradually accumulates over time. Intensity of infection and degree of morbidity are closely related.

Methodology/principal findings

This case series describes the medical history, the clinical pathology, the socio-economic and the environmental characteristics of very severe tungiasis in five patients living in traditional Amerindian communities in the Amazon lowland of Colombia. Patients had between 400 and 1,300 penetrated sand fleas. The feet were predominantly affected, but clusters of embedded sand fleas also occurred at the ankles, the knees, the elbows, the hands, the fingers and around the anus. The patients were partially or totally immobile. Patients 1 and 3 were cachectic, patient 2 presented severe malnutrition. Patient 3 needed a blood transfusion due to severe anemia. All patients showed a characteristic pattern of pre-existing medical conditions and culture-dependent behavior facilitating continuous re-infection. In all cases intradomiciliary transmission was very likely.

Conclusion/significance

Although completely ignored in the literature, very severe tungiasis occurs in settings where patients do not have access to health care and are stricken in a web of pre-existing illness, poverty and neglect. If not treated, very severe tungiasis may end in a fatal disease course.

Tungiasis (also called sand flea disease) is a neglected tropical disease (NTD) caused by the penetration of female sand fleas in the skin, typically at the toes, the sole or the heel. Once embedded in the upper strata of the skin, the parasite hypertrophies, enlarging its body size by a factor of 2000 within ten days. This causes intense inflammation with pain and itching, eventually leading to impaired mobility. During a period of three weeks, eggs are expelled through a tiny opening in the skin. When the last egg has been released into the environment, the parasite shrinks and eventually dies. Hence, by nature tungiasis is a self-limited infection. However, in endemic settings re-infection is the rule and parasite load gradually accumulates over time. Here we report five cases with extremely severe tungiasis in patients with 400 to 1,300 embedded sand fleas. Not only the feet were affected, but clusters of parasites also occurred at the ankles, the knees, the elbows, the hand, the fingers and around the anus. The patients were partially or totally immobile. Two patients were cachectic and one required a blood transfusion. All patients showed a characteristic pattern of pre-existing medical conditions and culture-related behaviour facilitating continuous re-infection.

Preferences of Pet Owners in Regard to the Use of Insecticides for Flea Control

A survey conducted from 2002 to 2012 of 759 customers from 84 veterinary practices allows us to examine the habits of dog and cat owners regarding the use of insecticides for flea control. The results indicate that the percentage of animals treated during the 12 mo prior to the survey was not very high (71% in dogs and 50% in cats), considering that 100% of animals included in the study were flea-infested. Statistical analysis shows that animals older than 4 mo are treated more frequently and that dogs are more likely to be treated than cats. Among cats, those living in houses with gardens or farms are treated at a higher rate than those that live in houses without gardens or in flats. The main variable associated with the degree of satisfaction and product loyalty is the active ingredient, and the choice of a commercial product is generally associated with high-efficacy products. The mode of application of a flea treatment does not seem to have a strong influence on pet owner satisfaction or loyalty. Likewise, we do not find a clear correlation between owners' satisfaction and loyalty, so pet owners may find the results of the selected product more or less satisfactory for reasons other than simple effectiveness. Finally, because of the complexity of the life cycle of these ectoparasites, the importance of the advice of a veterinarian when planning flea control is emphasized.

The Biology and Ecology of Cat Fleas and Advancements in Their Pest Management: A Review

The cat flea Ctenocephalides felis felis (Bouché) is the most important ectoparasite of domestic cats and dogs worldwide. It has been two decades since the last comprehensive review concerning the biology and ecology of C. f. felis and its management. Since then there have been major advances in our understanding of the diseases associated with C. f. felis and their implications for humans and their pets. Two rickettsial diseases, flea-borne spotted fever and murine typhus, have been identified in domestic animal populations and cat fleas. Cat fleas are the primary vector of Bartonella henselae (cat scratch fever) with the spread of the bacteria when flea feces are scratched in to bites or wounds. Flea allergic dermatitis (FAD) common in dogs and cats has been successfully treated and tapeworm infestations prevented with a number of new products being used to control fleas. There has been a continuous development of new products with novel chemistries that have focused on increased convenience and the control of fleas and other arthropod ectoparasites. The possibility of feral animals serving as potential reservoirs for flea infestations has taken on additional importance because of the lack of effective environmental controls in recent years. Physiological insecticide resistance in C. f. felis continues to be of concern, especially because pyrethroid resistance now appears to be more widespread. In spite of their broad use since 1994, there is little evidence that resistance has developed to many of the on-animal or oral treatments such as fipronil, imidacloprid or lufenuron. Reports of the perceived lack of performance of some of the new on-animal therapies have been attributed to compliance issues and their misuse. Consequentially, there is a continuing need for consumer awareness of products registered for cats and dogs and their safety.

Fleas and Ticks in Carnivores From a Domestic-Wildlife Interface: Implications for Public Health and Wildlife

Fleas and ticks are parasites of wild and domestic mammals, and can be vectors of several pathogens. In rural areas, domestic carnivores such as the domestic dog (Canis lupus familiaris L.), may act as a "bridge" between natural areas and human settlements where ectoparasites can be used as a metric of such link. The aim of this study was to identify fleas, ticks, and Rickettsia spp., collected from domestic and wild carnivores in a natural reserve and surrounding human settlements in Central Chile, using morphological keys and molecular analysis. We surveyed 170 households from which 107 dogs and eight cats were sampled. From the natural reserve, we sampled two chilla foxes (Pseudalopex griseus Gray), two lesser grison (Galictis cuja Molina), three kodkods (Leopardus guigna Molina), and four dogs. From dogs, we collected Ctenocephalides felis Bouché, Ctenocephalides canis Curtis, Pulex irritans L., and Rhipicephalus sanguineus s.l. Latreille; C. felis was the most frequent ectoparasite. Cats were infested only by C. felis and Rh. sanguineus s.l. From wild carnivores, we obtained C. canis and P. irritans, the latter being most frequent. Molecular analysis of P. irritans detected 10 haplotypes and two main clades, which tended to separate fleas from wild and domestic hosts. Molecular analysis of ompA and ompB genes confirmed the presence of Rickettsia felis in fleas collected from owned dogs and cats, which could represent a potential risk factor of R. felis transmission in the area.

Evaluation of pharmacokinetics and efficacy of ivermectin following oral administration in dogs against experimental infection of Ctenocephalides felis felis and Rhipicephalus sanguineus

With the increasing number of pets in home the human-animal relationship is increasingly close and care about control disease growing. Ivermectin (IVM) is frequently used because its proven safety. IVM is recommended for the treatment of demodectic scabies and prevention of heartworm in dogs, but informally is extremely used to control of Ctenocephalides felis felis and Rhipicephalus sanguineus. The aim of this study is evaluate the use of IVM in dogs, by the oral route at 0.6μg/kg dose, against experimental infection of these parasites using the construction of the plasma concentration curve and efficacy study. A IVM quantification method in canine plasma using HPLC-FL was developed and validated based on RE n°899/03 ANVISA. The samples collected during the efficacy test was analyzed by this validated method and prove C_max of 350ng/mL at 4h (t_max) and AUC of 8411ng/h/mL. Spite of formulation have shown good absorption, the highest efficiency values found for Rhipcephalus sanguineus and Ctenocephalides felis felis were very low, 35% and 67% respectively, demonstrating this not be the most appropriate treatment for the control of these parasites.

Prevalence of ectoparasites in owned dogs in Kerman city, southeast of Iran

The present study aimed to investigate the intensity and distribution of natural infestation of ectoparasites in owned dogs during June to November 2011 in Kerman city, southeast of Iran. One hundred two domestic dogs (63 males, 39 females) with age ranged between 45 days to 13 years were examined for ectoparasites infestation including (tick, lice, flea and mite) in Kerman city. Detailed questionnaire about grooming and bathing interval, keeping place (outdoor, indoor) and purpose of keeping were obtained from owners. After complete skin examination, animals hairs were combed and their skin rubbed with a piece of cotton soaked in alcohol to remove the ectoparasites in apparently normal cases, and deep skin scratching were prepared from all type of lesions in symptomatic dogs. A total number of 149 ectoparasites were collected. The most common ectoparasite was Rhipicephalus sanguineus tick, which infested 27 of the 102 dogs (26.47 %). Ctenocephalides canis was identified on two dogs (1.96 %) and 5 dogs infested with Hippobosca spp (4.9 %) that the highest infestation rate was seen in September (14.2 %). Studied samples were routinely checked for clinical symptoms. Itching and scratching lesions were the only reported signs which seen in flea infested dogs (6.4 %) and other infested dogs (93.5 %) had no clinical symptoms. Ectoparasites were significantly higher in outdoor dogs in compare with indoor group and the most tick infested location was ear (61.3 %) (P < 0.05).

Effect of host lizard anemia on host choice and feeding rate of larval western black-legged ticks (Ixodes pacificus)

Although ticks are known to exhibit preferences among host species, there is little evidence that ticks select hosts within a species based on physiological condition. It may be beneficial for ticks to choose hosts that are easier to feed upon if the ticks can perceive indicative chemical or other signals from the host. For example, if ticks can detect host hematocrit they may choose hosts with high hematocrit, facilitating a faster blood meal. It may similarly be adaptive for ticks to avoid anemic hosts because it may be difficult for them to obtain an adequate meal and feeding duration may be extended. We tested the hypothesis that larval western black-legged ticks (Ixodes pacificus) detect host hematocrit using external cues and choose healthy over anemic hosts, allowing them to feed more quickly. We presented groups of larval ticks with pairs of healthy and anemic male western fence lizards (Sceloporus occidentalis), allowed them to select a host, and measured the feeding duration of the ticks. We found that the ticks did not exhibit a statistically significant preference for healthy over anemic lizards, but that the ticks fed to repletion significantly faster on healthy hosts than on anemic hosts. Larval ticks may not be able to detect external cues indicating the health of the host, at least not in terms of their hematocrit. The extended feeding duration likely reflects the extra time needed for the ticks to concentrate the blood meal of their anemic hosts.

Survey of flea infestation in cats in Spain

Fleas are a common cause of feline skin disorders as well as vectors of zoonotic diseases. This study evaluated the flea species infesting domestic cats in Spain and assessed factors influencing their distribution. Fleas from 217 cats from 57 localities in Spain were identified and associations between abundance, and host-dependent, host habitat and environmental factors were examined. Variations in infracommunity and component community structure were also explored. Three species were present, of which Ctenocephalides felis (Bouché) (Siphonaptera: Pulicidae) was the most abundant (98.4%), followed by Ctenocephalides canis (Curtis) (1.1%) and Pulex irritans (L.) (Siphonaptera: Pulicidae) (0.5%). Overall abundance and abundances of both C. felis and C. canis were higher on farms than in apartments, but overall flea abundance and abundances of both C. felis and C. canis were lower in rural than urban environments. Overall abundance and C. felis abundance were lower during the warmest months, and mean annual rainfall was positively correlated with overall, C. felis and C. canis abundances. No relationship between the number of species per cat and any host, habitat or physiographical variable was found. Species richness was not correlated with mean annual temperature or rainfall. Flea abundance was mainly associated with host habitat and environmental factors.

First report of Ctenocephalides felis felis infestation of buffalo calves in Punjab, India

Two female buffalo calves of approximately 3 months of age from Hoshiarpur and Gurdaspur districts of Punjab state, India were found to be moderately infested with the cat flea Ctenocephalides felis felis. The calves were apparently healthy with no clinical signs and skin lesions. The calves were also found to be simultaneously infested with ixodid tick (Rhipicephalus (Boophilus) microplus). Infestations of buffalo calves by C. felis felis is reported for the first time.

Predictors for abundance of host flea and floor flea in households of villages with endemic commensal rodent plague, Yunnan Province, China

BACKGROUND

From 1990 to 2006, fifty-five natural villages experienced at least one plague epidemic in Lianghe County, Yunnan Province, China. This study is aimed to document flea abundance and identify predictors in households of villages with endemic commensal rodent plague in Lianghe County.

METHODS

Trappings were used to collect fleas and interviews were conducted to gather demography, environmental factors, and other relevant information. Multivariate hurdle negative binomial model was applied to identify predictors for flea abundance.

RESULTS

A total of 344 fleas were collected on 101 small mammals (94 Rattus flavipectus and 7 Suncus murinus). R. flavipectus had higher flea prevalence and abundance than S. murinus, but the flea intensities did not differ significantly. A total of 315 floor fleas were captured in 104 households. Xenopsylla cheopis and Ctenocephalides felis felis were the predominant flea species on the host and the floor flea, respectively. The presence of small mammal faeces and R. flavipectus increased host flea prevalence odds 2.9- and 10-fold, respectively. Keeping a dog in the house increased floor flea prevalence odds 2-fold. Keeping cattle increased floor flea intensity by 153%. Villages with over 80% of houses raising chickens had increased prevalence odds and intensity of floor flea about 2.9- and 11.6-fold, respectively. The prevalence and intensity of floor flea in brick and wood houses were decreased by 60% and 90%, respectively. Flea prevalences of host and floor flea in the households that were adjacent to other houses were increased 7.4- and 2.2-fold, respectively. Houses with a paddy nearby decreased host flea intensity by 53%, while houses with an outside toilet increased host flea intensity by 125%.

CONCLUSION

Rodent control alone may not be sufficient to control plague risk in these areas. In order to have successful results, plague control programs should pay attention to ecological and hygiene factors that influence flea populations.

A survey of ectoparasite infestations in stray dogs of Gwang-ju City, Republic of Korea

This study was designed to investigate the incidence of ectoparasite infestation among stray dogs in Gwang-ju City, Republic of Korea. A total of 103 stray dogs collected in the Animal Shelter of Gwang-ju City from November 2003 to August 2005 were investigated in this study. Ectoparasites of one or more genera were detected in 45.6% (47 / 103) of the dogs examined for dermatologic lesions and/or skin scrapings (from 3-5 affected areas). Otodectes cynotis was found to be the most frequent parasite (22.3%, 23 / 103), followed by Sarcoptes scabiei var canis (19.4%, 20 / 103), Ctenocephalides canis (6.8%, 7 / 103), Demodex canis (4.9%, 5 / 103), and Trichodectes canis (1.0%, 1 / 103). Monospecific infestation was found in 83.0% (39 / 47) of the affected dogs, whereas concurrent infestations with 2 or more ectoparasites per animal were found in 17.0% (8 / 47) of the affected dogs. Trichodectes canis is reported for the first time in the Republic of Korea. Dogs less than 1 yr old were more heavily infected than other age groups (66.7%), and small-sized dogs of less than 3 kg body weight were more heavily infected than larger dogs (41.7%).

Flea blood feeding patterns in cats treated with oral nitenpyram and the topical insecticides imidacloprid, fipronil and selamectin

A series of studies was conducted to determine the effect of systemically and topically active insecticides on blood consumption by fleas (Ctenocephalides felis). Infestations were conducted by placing fleas into plexi-glass chambers attached to the lateral rib cage of domestic short-hair cats. After pre-defined periods, fleas and flea feces were extracted using vacuum aspiration and spectrophotometrically analyzed for hemoglobin using Drabkin's reagent. To determine how rapidly nitenpyram kills actively feeding fleas, a single oral treatment was administered 24h after infestation. To determine the effect of nitenpyram on blood consumption of newly acquired fleas, cats were infested with fleas 1h post-treatment and fleas and flea feces from both studies were extracted at 15, 30, 60, 120, 240 and 480min post-treatment or post-infestation. To compare the effects of topically versus systemically active insecticides, 20 cats each with 2 chambers attached, were randomly allocated among groups and were infested with fleas 1h after each of 4 nitenpyram treatments, or at 7, 14, 21 and 28 days after a single application of commercial spot-on formulations of fipronil, imidacloprid or selamectin. Infestations were also completed for untreated (control) cats. Twenty-four hours after infestation, fleas and flea feces were removed for host blood quantification. If at any time, flea blood consumption in a treated group did not significantly differ from that of fleas infesting controls, that treatment group was withdrawn from the study. Nitenpyram effects on actively feeding fleas were first observed at 60min post-dosing when 38% of fleas were dead or moribund, and at 240min 100% were dead or moribund. Nitenpyram produced a significant reduction in flea blood consumption (p<0.05), which appeared to cease 15min after infestation. For the treatment comparisons, significantly more (p<0.05) blood was consumed by fleas taken from imidacloprid and fipronil-treated cats than from the nitenpyram or selamectin groups. Only on nitenpyram- or selamectin-treated cats were there significant reductions (p<0.05) in flea blood consumption on days 21 and 28, with significant difference (p>0.05) between these two groups on day 28. In this study systemically acting insecticides such as nitenpyram, and the topically applied but systemically active insecticide selamectin, were more effective in interfering with flea blood feeding than were imidacloprid and fipronil.

Epidemiology of flea infestation of ruminants in Libya

The results of an epidemiological and clinical study of flea infestations of farm animals in northern Libya is reported. Of 12,130 sheep examined from 124 flocks, 150 sheep were found to be infested with fleas from 50 different flocks. Likewise 23 goats from 2981 examined, and 11 calves from 1124 cattle examined were infested No fleas were recovered from camels or horses. Of 1861 fleas recovered from farm livestock, 1857 were Ctenocephalides felis strongylus and 4 were Pulex irritans. Dogs from farms and local clinics were also examined. Eight farms dogs were found to be infested with P. irritans. Of 79 infested dogs examined in veterinary clinics, 53 were found infested with P. irritans, 11 with Ctenocephalides felis felis, 12 had a mixed infestation of P. irritans and C. felis felis. Single dogs had mixed infestation of P. irritans and C. canis; C. felis felis and C. canis; and P. irritans, C. felis felis and Echidnophaga gallinacia. C. felis felis was also found on 15 infested cats. C. felis felis was never found on large farm animals despite frequently sharing their environment with dogs or cats. Likewise C. felis stongylus was never isolated from dogs or cats. This is consistent with the hypothesis that C. felis strongylus has become adapted to large farm animals, whilst C. felis felis is better adapted to dogs and cats. However, four stockmen were found infested with a total of 176 C. felis strongylus, which suggests that this subspecies is also a potential zoonosis. A significantly higher proportion of intensive farms had animals with flea infestation compared to semi-intensive farms. Fleas were not found in nomadic herds. Infested farm animals often presented with excoriation, alopecia, pruritus and hyperkeratitis particularly on the lower limbs. These signs are consistent with the generation of flea-bite hypersensitivity.

Tick control: an industry point of view

The development of new acaricides is a long and very expensive process. Worryingly, there is increasing resistance to available acaricides worldwide leading to the real possibility that our dwindling supply of effective acaricides will be exhausted unless action is taken to increase the number of new acaricidal products and reduce the rate of resistance development. In 1995, eight major animal health pharmaceutical companies formed the Veterinary Parasite Resistance Group (VPRG) to act as an expert consultative group to guide the FAO in resistance management and collaborate in the prudent use of acaricides. In this paper, members of the VPRG discuss the problems and processes in acaricide development, resistance in the field to commonly used acaricides and the different considerations when targeting the cattle and pet market, and give their view of the future for tick control from the perspective of the animal health industry.

Fipronil: environmental fate, ecotoxicology, and human health concerns

Fipronil is a highly effective, broad-spectrum insecticide with potential value for the control of a wide range of crop, public hygiene, amenity, and veterinary pests. It can generally be applied at low to very low dose rates to achieve effective pest control. Application rates vary between 0.6 and 200 g a.i./ha, depending on the target pest and formulation. It belongs to the phenyl pyrazole or fiprole group of chemicals and is a potent disrupter of the insect central nervous system via interference with the gamma-aminobutyric acid (GABA-) regulated chloride channel. Fipronil degrades slowly on vegetation and relatively slowly in soil and in water, with a half-life ranging between 36 hr and 7.3 mon depending on substrate and conditions. It is relatively immobile in soil and has low potential to leach into groundwater. One of its main degradation products, fipronil desulfinyl, is generally more toxic than the parent compound and is very persistent. There is evidence that fipronil and some of its degradates may bioaccumulate, particularly in fish. Further investigation on bioaccumulation is warranted, especially for the desulfinyl degradate. The suitability of fipronil for use in IPM must be evaluated on a case-by-case basis. In certain situations, fipronil may disrupt natural enemy populations, depending on the groups and species involved and the timing of application. The indications are that fipronil may be incompatible with locust IPM; hence, this possibility requires further urgent investigation. It is very highly toxic to termites and has severe and long-lasting negative impacts on termite populations. It thus presents a long-term risk to nutrient cycling and soil fertility where termites are "beneficial" key species in these ecological processes. Its toxicity to termites also increases the risk to the ecology of habitats in which termites are a dominant group, due to their importance as a food source to many higher animals. This risk has been demonstrated in Madagascar, where two endemic species of lizard and an endemic mammal decline in abundance because of their food chain link to termites. Fipronil is highly toxic to bees (LD50 = 0.004 microgram/bee), lizards [LD50 for Acanthodactylus dumerili (Lacertidae) is 30 micrograms a.i./g bw], and gallinaceous birds (LD50 = 11.3 mg/kg for Northern bobwhite quail), but shows low toxicity to waterfowl (LD50 > 2150 mg/kg for mallard duck). It is moderately toxic to laboratory mammals by oral exposure (LD50 = 97 mg/kg for rats; LD50 = 91 mg/kg for mice). Technical fipronil is in toxicity categories II and III, depending on route of administration, and is classed as a nonsensitizer. There are indications of carcinogenic action in rats at 300 ppm, but it is not carcinogenic to female mice at doses of 30 ppm. The acute toxicity of fipronil varies widely even in animals within the same taxonomic groups. Thus, toxicological findings from results on standard test animals are not necessarily applicable to animals in the wild. Testing on local species seems particularly important in determining the suitability of fipronil-based products for registration in different countries or habitats and the potential associated risk to nontarget wildlife. Risk assessment predictions have shown that some fipronil formulations present a risk to endangered bird, fish, and aquatic and marine invertebrates. Great care should thus be taken in using these formulations where they may impact any of these endangered wildlife groups. Work in Madagascar has highlighted field evidence of this risk. The dose levels at which fipronil produces thyroid cancer in rats are very high and are unlikely to occur under normal conditions of use. There is also dispute as to whether this is relevant to human health risk. However, as fipronil is a relatively new insecticide that has not been in use for long enough to evaluate the risk it may pose to human health, from data on human exposure to the product, a precautionary approach may be warranted. The use of some fipronil-based products on domestic animals is not recommended where handlers spend significant amounts of time grooming or handling treated animals. In general, it would appear unwise to use fipronil-based insecticides without accompanying environmental and human health monitoring, in situations, regions, or countries where it has not been used before, and where its use may lead to its introduction into the wider environment or bring it into contact with people. Further work is needed on the impacts of fipronil on nontarget vertebrate fauna (amphibians, reptiles, birds, and mammals) in the field before the risk to wildlife from this insecticide can be adequately validated. Further field study of the effects of fipronil on the nutrient cycling and soil water-infiltration activities of beneficial termites is required to assess the ecological impacts of the known toxicity of fipronil to these insects.

Prevalence of ectoparasites in a population of feral cats from north central Florida during the summer

Ectoparasites are a common and important cause of skin disorders in cats. Ectoparasites are capable of disease transmission and can cause life-threatening anemia in young or debilitated animals. The objective of this study was to determine the potential feline ectoparasites in domestic cats by using a cohort of feral cats from north central Florida that have not received veterinary care and have no known exposure to insecticide application. A total of 200 feral cats were randomly selected for this study. Four monthly sessions were scheduled for feral cat ectoparasite examination and sample collection. Five minutes flea combing revealed that 185/200 (92.5%) of the cats were infested with fleas. The cat flea, Ctenocephalides felis was the most common flea infesting 92.5% feral cats (mean = 13.6; standard deviation +/- 16.4 fleas per cat). Pulex simulans was identified on 9/200 (4.5%) (mean = 1 +/- 0.50 fleas per cat). Echidnophaga gallinacea was found on 11/200 (5.5%) of cats (mean = 14.8 +/- 9.63 fleas per cat). There was a significant difference (P = 0.0005) in the average number of C. felis counted per cat between months. Mean counts in June (18.3 +/- 2.4) and July (16.6 +/- 2.1) were significantly (P < 0.01) higher than in August (8.4 +/- 2.5) and September (7.7 +/- 2.0). Only 15/200 cats had skin disease. Flea infestation may potentially be the underlying cause in 10/15. Otoscopic examination of both ears revealed mite movement and black ceruminous exudate typically indicative of the presence of Otodectes cynotis in 45/200 (22.5%) cats. Examination of a swab specimen from both ear canals of all cats revealed O. cynotis in 74/200 (37%) cats. Of 74 cats positive on ear swab, 8 (10.8%) showed a normal ear canal appearance (no or mild ceruminous exudate) in both ears upon otoscopic examination. A total of nine ticks were recovered from five cats. The number and species of ticks recovered were: one adult female Rhipicephalus sanguineus; one adult female Amblyomma americanum; one adult male A. americanum; five adult female Dermacentor variabilis; and one adult female Ixodes scapularis. All superficial skin scrapes were negative. Hair clippings from the abdomen of all cats revealed 2/200 (1%) of the cats were infested with Felicola subrostratus.