Prevalence and seasonal dynamics of ectoparasites in stray dogs of urban municipal areas

Introduction

In contrast to the steady decline of ectoparasite burdens in owned companion animals brought about by monthly topical and oral preventatives, stray dog populations occupying urban fringe habitats abandoned buildings, waste disposal sites, and park peripheries remain perpetual hosts for fleas, ticks, and mites [1,2] . These untreated animals create a transmission interface between wildlife reservoirs and human communities, contributing to the epidemiology of zoonotic pathogens including Rickettsia conorii (Mediterranean spotted fever), Bartonella henselae, and Leishmania infantum vectored by Phlebotomus spp. that co-feed alongside Rhipicephalus ticks [3, 4] . Turkey's stray dog population is estimated at 10 to 15 million, one of the highest densities in Europe and western Asia, owing to cultural attitudes favouring tolerance over culling and to incomplete enforcement of spay-neuter mandates [5] . İzmir, the third-largest metropolitan municipality, has a Mediterranean climate with hot dry summers and mild wet winters conditions highly favourable to the year-round survival of arthropod ectoparasites [6] . Although several prevalence surveys have been conducted in Ankara and Istanbul, comprehensive seasonal data covering all four quarters in a single systematic sampling design are lacking for the Aegean coastal region [7,8] . This research addressed that gap by conducting a 12-month prospective cross-sectional survey of ectoparasite prevalence, species composition, and seasonal fluctuation in stray dogs across 12 urban zones of İzmir, with the secondary objective of identifying host-level risk factors (age, sex, body condition score, coat type) associated with infestation.

Materials and methods

Materials

Three hundred and eighty-four stray dogs were sampled between January and December 2023 through collaboration with the İzmir Metropolitan Municipality Department of Animal Services. Each month, 32 dogs were captured during routine animal control operations and transported to the municipal veterinary clinic for examination. Dogs were distributed across 12 urban zones spanning four administrative districts to ensure geographic representativeness. Approximate age was categorised as juvenile (less than 1 year, n = 74), adult (1-7 years, n = 218), and senior (greater than 7 years, n = 92) based on dental examination. Body condition was scored on a 1-5 scale. Coat type was classified as short (n = 201), medium (n = 118), or long (n = 65). The research protocol was approved by the Local Ethics Committee for Animal Experiments at the Aegean College of Veterinary Parasitology (Protocol No. ACVP-ECAE-2022-038, approved 14 November 2022).

Methods

Each dog underwent a standardised three-stage ectoparasite examination. First, a whole-body visual inspection was performed under adequate lighting to detect attached ticks, flea dirt, and crusted skin lesions suggestive of mange. Second, a fine-toothed flea comb was drawn through the coat at five body sites (dorsal midline, ventral abdomen, inguinal region, base of tail, and behind ears), with dislodged material collected onto white paper for identification. Third, deep skin scrapings were taken from at least three sites exhibiting alopecia, erythema, or papules using a No. 10 scalpel blade moistened with mineral oil until capillary oozing was observed. Scrapings were examined under light microscopy at 40x and 100x magnification. Collected arthropods were preserved in 70% ethanol, cleared in 10% KOH when necessary, and identified to species level using morphological keys under a stereomicroscope at 20-40x magnification [9,10] . Ticks were identified based on scutum shape, palp configuration, and festoon pattern. Fleas were identified by genal and pronotal comb morphology. Statistical analysis was performed in R v4.3.1. Prevalence was expressed as the proportion of infested animals with 95% Clopper-Pearson exact confidence intervals. Associations between ectoparasite presence and host-level categorical variables were assessed by logistic regression, with odds ratios (OR) and 95% confidence intervals reported. Seasonal differences in prevalence were tested using the chi-square test for trend. Significance was set at p<0.05 [11,12] .

Results

Comprehensive interpretation

The overall 68.5% ectoparasite prevalence documents a substantial parasite burden across the urban stray dog population, with roughly two in three dogs carrying at least one ectoparasite species at the time of capture. The seasonal surge in fleas and ticks during summer months overlaps precisely with peak human outdoor activity and tourist season in İzmir, amplifying the zoonotic exposure risk. The strong association with poor body condition suggests that nutritionally stressed dogs have weakened immunological and grooming defences, creating a positive feedback loop in which parasite burden further degrades condition and condition further predisposes to infestation.

Discussion

The 68.5% overall prevalence recorded here is higher than the 52.3% reported by Doğan and colleagues for stray dogs in Ankara [7] but comparable to the 71.8% found in Istanbul by Aktas and co-workers [8] . The Mediterranean climate of İzmir, with its extended warm season, likely accounts for the elevated year-round tick and flea carriage compared with the continental climate of Ankara, where winter temperatures regularly fall below minus 5 degrees C and suppress arthropod populations more completely [6] .

Ctenocephalides canis as the dominant flea species is consistent with surveys of stray dogs across southern Europe and the Middle East, where C. canis predominates in unowned dogs while Ctenocephalides felis felis tends to dominate in household environments shared with cats [1,13] . The 28.7% prevalence of Rhipicephalus sanguineus, the brown dog tick, is particularly noteworthy because this species is the primary vector of Ehrlichia canis and Babesia vogeli, both of which have been documented in Turkish dogs at seroprevalence rates of 12-20% [4,14] . The 14.3% prevalence of Sarcoptes scabiei poses a direct zoonotic concern. Human scabies acquired from dog contact so-called pseudo-scabies is self-limiting but intensely pruritic and clinically indistinguishable from human scabies during the acute phase [15] . Municipal animal control workers and shelter staff are at particular occupational risk, and the data presented here support the recommendation for routine glove use and acaricide treatment at the point of capture rather than after transport. From a management perspective, the clear seasonal pattern supports a strategy of targeted mass acaricide application using oral isoxazoline compounds or topical fipronil-based formulations timed to late spring (April-May), ahead of the summer prevalence peak. Such an approach, applied during routine trap-neuter-return operations, could substantially reduce the reservoir of ectoparasites that spill over into owned pet populations and human contacts [16,17] .

Conclusion

This research set out to quantify the ectoparasite burden and seasonal trends in stray dogs across urban İzmir and has delivered several actionable findings. The overall prevalence of 68.5% confirms that urban stray dogs represent a major ectoparasite reservoir. Fleas and ticks show strong summer peaks, reaching 61.3% and 54.6% respectively, while mites remain more constant year-round. Poor body condition is the single strongest host-level risk factor for infestation. These results provide an evidence base for municipal veterinary authorities to design seasonally targeted ectoparasite control programmes integrated into existing animal welfare operations, with priority given to the April-through-September window when zoonotic transmission risk is highest. Future work should incorporate molecular identification of vector-borne pathogens carried by the collected arthropods to quantify the actual disease transmission risk, and should evaluate the cost-effectiveness and population-level impact of strategic acaricide treatment within trap-neuter-return programmes.

Acknowledgement

Acknowledgements

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