Qualitative and quantitative observations on the flea population dynamics of dogs and cats in several areas of Germany

Abstract

From an ongoing country-wide study on the spectrum, the epidemiology and the population dynamics of flea infestations in dogs and cats, important preliminary results from the three areas of Karlsruhe, Nuernberg and Leipzig are presented. A total of 1922 dogs and 1838 cats from 12 different veterinary practices or clinics in three areas of Germany were systematically examined between July 2003 and June 2004. All dogs and cats appearing for a clinical veterinary consultation on one regular working day per month, per practice, were clinically examined. Dogs and cats were examined irrespective of any kind of prior therapeutic or prophylactic insecticidal treatment. The results show that a total of 99 dogs (5.13%) and 263 cats (14.33%) were infested. Cats were more often flea-infested than dogs (p < 0.05). The highest infestation rates for dogs ($\overline{x}=7.87\%$) were detected between July and October, and for cats ($\overline{x}=21.14\%$) between July and September, the lowest infestation rates for dogs ($\overline{x}=2.88\%$) were observed between November and May, and for cats ($\overline{x}=12.16\%$) between November and April (p < 0.05). Although the prevalences were generally higher during the summer months, no statistical differences were detectable when looking at the pattern between the four seasons, neither for dogs, nor for cats. Interestingly, the highest prevalences in dogs (9.9%) were detected in June 2004 and comparatively, in cats (23.86%) in August. The lowest detection rates in dogs were seen (1.28%) in April and in cats (7.26%) in January. The preliminary results did not indicate any tendency for a relationship between climatic conditions and flea infestation rates. Similarly, no differences of the infestations rates were detectable between urban and rural areas, 56% (dogs) and 46% (cats) of the infested pets originated from urban habitats. The flea species collected include Ctenocephalides felis, Ctenocephalides canis, Archaeopsylla erinacei, Pulex irritans, Ceratophyllus gallinae, etc. The overall frequencies reveal that C. felis was the most prominent species (81.5%), followed by C. canis (12.5%), A. erinacei (2.7%) and P. irritans (1.7%).

Introduction

Flea infestations are a common cause of skin disorders and for consultations in small animal practice. The cat flea, Ctenocephalides felis, is one of the most frequent external parasites of companion animals worldwide (Rust and Dryden, 1997). C. felis is generally regarded the predominant species to find on dogs and cats (Halliwell, 1983, Harman et al., 1987, MacDonald, 1993, Visser et al., 2001, Muller et al., 2001, Akucewich et al., 2002). Other frequent flea species in the United States affecting dogs and cats are Ctenocephalides canis, Pulex irritans and Echidnophaga gallinacea (Scheidt, 1988). The sticktight flea of poultry, E. gallinacea, seems to be a frequent parasite of dogs and cats in the southeast of the USA (Kalkofen and Greenberg, 1974, Scott, 1980). The most prevalent flea species on dogs and cats in Germany are C. felis (on dogs: 71.1%, on cats: 83.5%), C. canis (on dogs: 3.4%, on cats: 0) and Archaeopsylla erinacei (on dogs: 14.6%, on cats: 5.1%) (Visser et al., 2001). In another study from Munich 5.5% of the examined dogs and 18.9% of the cats were infested with several flea species (Kalvelage and Münster, 1991). In UK C. felis and C. canis were selected from both dogs and cats, with a marked preponderance of the cat flea on both animal species (Chesney, 1995). A further survey from England examined the flea community on dogs and cats; from all fleas 96.4% (N = 133) were C. felis and 3.6% (N = 5) were C. canis, no other specimens of flea was observed (Clark, 1999). Those tendencies are in agreement with results obtained in Denmark (Kristensen et al., 1978), and in Finland (Saari and Nikander, 1991). C. canis, on the other hand, was in Ireland (Baker and Hatch, 1972) and New Zealand (Guzman, 1984) the most common identified flea species from dogs. In Mexico Cruz-Vazquez et al. (2001) confirmed an overall flea infestation of 30.3% and 30.1% for dogs and cats, respectively. Moreover 92.3% of the cats were infested with C. felis, 7.7% had both flea species; whereas on dogs, 81.1% were parasitized with only C. felis, 16.8% with C. canis, and 2% with C. felis and C. canis. The cat flea was the most prevalent flea species found other than C. canis; no other flea species were detected on the examined pets. It appeared that the life cycle of those external parasites continues throughout the year. The only species of fleas found on dogs in Chile were C. felis (41.8%), C. canis (39.4%), and P. irritans (18.8%); in Santiago C. felis was the predominant species on dogs (80.5%) (Alcaino et al., 2002). However, there are differences in the spectrum of various flea species related to geographical areas (rural versus urban; landscape: mountains versus plain and/or waterfront), seasonal occurrence, and the host susceptibility for those ectoparasites (Harman et al., 1987, Scheidt, 1988, Cruz-Vazquez et al., 2001).

This paper reports on epidemiological investigations in three areas, located in different parts of Germany, to determine the importance of fleas on dogs and cats and the fact that there are differences with respect to their prevalence, geographical distribution, and the influence of the seasons on the flea population development. Furthermore, collected flea specimens were identified after removal from the animal hosts. The spectrum of flea species sampled from dogs and cats in this country-wide study is reported.