Abstract
The seasonal occurrence of Ctenocephalides felis felis (Bouché) and Ctenocephalides canis (Curtis) infestation on dogs and cats in Cuernavaca City in Mexico, was determined by examining 1,803 dogs and 517 cats at two veterinary clinics during 1995-1997. The overall flea infestation was 30.3 and 30.1% for dogs and cats, respectively. There were no significant differences (P > 0.05) in percentage of infestation among years for both hosts. The infestation was somewhat higher in spring, summer, and autumn than in winter, but no statistical differences was found among seasons (P > 0.05) for both pets. No relationship existed between percentage of flea infestation and temperature or rainfall among seasons. On dogs, 81.1% were infested with only C. felis felis, 16.8% with C. canis, and 2% had both flea species; whereas 92.3% of the cats were infested with C. felis felis and 7.7% with C. felis felis and C. canis. The cat flea was the most prevalent flea species found other than C. canis; no other species were found on the dogs and cats. It appeared that flea life cycle development continued throughout the year.
Cat and dog fleas, Ctenocephalides felis felis (Bouché) and Ctenocephalides canis (Curtis), are hematophagus ectoparasites that have a world wide distribution. Flea infestation is a common problem in pets and in the home environment, which causes severe nuisance and irritation to animals and humans. They also serve as intermediate hosts of internal parasites and vectors of organisms that cause diseases of veterinary and human importance (Harwood and James 1979). In Mexico, C. felis felis and C. canis are wide spread but their presence is more important in the warmer and humid regions (Quintero 1992). However, little is known about some aspects of dog and cat infestation and the relationship of these fleas with environmental parameters, which limits effective management and control alternatives.
The objective of this study was to determine the species and seasonal occurrence of flea infestation on dogs and cats in Cuernavaca, Mexico.
Materials and Methods
The study was conducted in Cuernavaca City, the capital of the state of Morelos, located in the central part of Mexico. Its altitude ranges between 1,529 and 1,560 m above sea level and has an annual precipitation of 1,200 mm with a warm subhumid climate and rainy summer season.
Between January 1995 and December 1997, 1,803 dogs and 517 cats were examined in two private veterinary clinics. On 1 d each week throughout this period, all dogs and cats received in the clinics were thoroughly examined to determine the presence of fleas from the head, neck, dorsum, trunk, limbs, tail, and ventral region. We considered a dog or cat to be infested when six or more fleas were detected over the body, because this is the number thought to be necessary to establish fleas in a yard or household. In addition, six fleas were collected from the animal body with the alcohol–ether-impregnated cotton and placed in a glass vial containing 70% ethanol for later preparation and identification using appropriate keys (Soulsby 1982, Quintero 1992).
A weekly record of the daily mean temperature (°C) and the total rainfall (mm) was obtained from the climatological station located in Cuernavaca City. The number of infested dogs and cats per week, month, and year during the study period and the seasonal occurrence of flea infestations were recorded. Chi-square test for 4 × 3 contingency table (Pagano and Gauvreau 1993) were used to compare proportions of infested dogs or cats among seasons and years (P < 0.05). Seasonal infestation percentages were correlated using the Pearson correlation coefficient (P < 0.01) with temperature and total rainfall for each season using SAS (SAS Institute 1985).
Results
Dogs and cats were found infested with C. felis felis and C. canis throughout the year. The seasonal occurrence is given in Tables 1 and 2. During 3 yr, 1,803 dogs and 517 cats were examined, and 31.3, 28.8, and 30.7% of dogs and 29.6, 30.8, and 29.9% of the cats were infested in 1995, 1996, and 1997, respectively. There were no significant differences in percentage infested among years (P > 0.05) during the 3-yr period, 30.3 and 30.1% of the dogs and cats were infested, respectively. During the spring, summer, and autumn the percentage was higher but no statistical difference existed among the seasons (P > 0.05). No statistically significant relationship was found between infestation percentage and temperature or rainfall during any season.
Seasonal occurrence of fleas infesting dogs in Cuernavaca City, Mexico (1995–1997)
Seasonal occurrence of fleas infesting dogs in Cuernavaca City, Mexico (1995–1997)
Seasonal occurrence of fleas infesting cats in Cuernavaca City, Mexico (1995–1997)
Seasonal occurrence of fleas infesting cats in Cuernavaca City, Mexico (1995–1997)
We collected and identified 4,218 fleas, of which 84% were C. felis felis and 16% were C. canis. No other flea species was found. The seasonal distribution of fleas found on dogs and cats by flea species is shown in Table 3. We found that 81.1% of the dogs examined were infested only with C. felis felis, 16.8% with only C. canis, and 2% were infested with both species. Cats were infested with only C. felis felis in 92.3% of the examinations and with C. canis and C. felis felis in 7.7% of those examined. The cat flea was the most prevalent flea species.
Distribution of dogs and cats infested by different flea species in Cuernavaca City, Mexico
Distribution of dogs and cats infested by different flea species in Cuernavaca City, Mexico
Discussion
Infestations of C. felis felis and C. canis were observed on dogs and cats throughout each year during the 3-yr study. The highest percentage infestations were found in spring, summer, and autumn and were lower in winter. The climatic conditions in the study area and the continuous presence of the hosts favored flea development throughout the year. The environmental conditions in yards and households are important to flea development, and temperature and relative humidity are factors that limit population development. Extreme temperature, >35 or <3°C combined with ≤33% RH reduce flea population development (Harwood and James 1979; Silverman and Rust 1981, 1983). In Cuernavaca City, the climatic conditions were uniform throughout the year with a 21.5°C mean temperature in the spring, summer, and autumn and 19.3°C in winter. The relative humidity was ≥60% in all seasons and appeared to provide ideal outdoor environmental conditions for flea development. The health of the domestic pet host is important in flea development, but it is not as important as the outdoor climate throughout the year. The uniform environmental conditions in the area were thought to explain the infestation levels observed throughout the year.
In general our observations were similar with that of other studies reported from other areas of the world in which the environmental conditions have been found to regulate flea populations (Amin 1966, Beresford-Jones 1981).
In the current study, the cat flea, C. felis felis, was the most prevalent flea species during all seasons of the year. Similar observations have been reported in North America and in other regions of the world (Dryden and Rust 1994). The epidemiological role of the cat flea as a vector of organisms that cause diseases in dogs and cats is unknown in this study area but research is needed to determine this role in disease occurrence. The data obtained in the current study on the seasonal infestation and species can provide a basis for additional work directed at the development of flea management systems.
In conducting the research described in this report, the investigators adhered to the "Guide for the Care and Use of Laboratory Animal’s" as promulgated by the Committee on Care and Use of Laboratory Animals of the Institute of Laboratory Animal Resources, National Research Council. The facilities are fully accredited by the American Association of Laboratory Animal Care.
References Cited
