Multicentre Study of Endo-Ectoparasite Infection in Italian Cats

Parasites infecting cats include protozoa, helminths and arthropods. Many are also transmissible to humans. Effective control relies on knowledge of parasite distribution and risk factors for infection. The present study was aimed at evaluating prevalence of major feline parasites in Italy and risk factors associated with their occurrence. Over a 12-month study period, thirteen study centers across Italy analyzed feces, hair and ectoparasites from naturally infected cats coming from feral colonies, shelters and private households. Samples from cats (n=987) were analyzed by all centers using the same diagnostic methods. Prevalence values and risk factors were evaluated statistically for identication of predictors of risk.


Background
Numerous parasites infect domestic cats. Among these, helminths of the gastro-intestinal tract and respiratory system can cause severe disease if parasite loads are heavy, while different arthropods can cause skin disease and allergy. Subclinical infection is of equal concern given the zoonotic nature of several feline helminths and the capacity of eas and ticks to transmit pathogens to cats, other animals and humans. Recent multicenter studies in both Europe and Italy, have been carried out to de ne the current status of endo-and ectoparasite infections of cats [1][2][3][4]. According to these, infections are widespread and depend on various risk factors, including lifestyle, geographical area and frequency of anti-parasitic treatment. Most studies on prevalence, distribution and risk factors for feline parasites in Italy have been carried out in central and southern areas of the country [5][6].
Multicenter studies provide useful information on distribution and risk of parasite infection. However, few apply the same, standard diagnostic protocols for each center, thus compromising reliability of results. Indeed, it has been reported that different copromicroscopic techniques have differing sensitivity, speci city and accuracy for the diagnosis of gastro-intestinal (GI) and broncopulmonary (BP) nematodes. The Mini-FLOTAC technique [7] has been recently demonstrated to be a highly sensitive method for diagnosing parasitic infections of human and veterinary importance where larvae or ova of parasites are shed in the faeces [8][9][10][11].
Seasonality of parasite infection in cats has been evaluated mostly from retrospective, longitudinal studies [12][13]. It is possible that sampling and analysis over a xed period of time may give more useful information on the current effects of season on parasite prevalence.
The aims of the present multicenter study were therefore to: (i) determine the current prevalence of feline endo and -ectoparasites throughout Italy by recruitment of cats from all regions; (ii) evaluate seasonal trends by recruiting a set number of cats each month consecutively over a 12-month period; (iii) use standardized diagnostic methods in order to eliminate variables associated with differences in test sensitivities/speci cities/accuracy; (iv) identify those factors that signi cantly increase the risk of infection.

Animals and study period
The study began in July 2019 and ended in September 2020. Thirteen University study centers participated, and each had a recruitment target of 7 cats/month for 12 months, for a total of 84 cats/center. Each cat could only be included in the study once, with no more than 2 cats from the same home/shelter/colony sampled.

Enrollment and sample collection
Inclusion criteria included: outdoor access; no antiparasitic treatment (endo and/or ecto) in the 3 months prior to enrollment and signed informed consent. Exclusion criteria included: no outdoor access; antiparasitic treatment (endo and/or ecto) in the 3 months prior to enrollment.
At enrollment, general information, inclusion criteria, clinical observations, frequency of antiparasitic treatments in the previous 12 months, and eventual signs of ecto-parasitic infection were recorded, and online data collection sheet lled (Supplementary Material   Table S1). Any observed ticks/nits (lice) were collected and stored in 80% ethanol pre-lled tubes. Each cat was combed with a ea comb for 5 minutes and collected material was stored in the zip-lock plastic bag at +4°C. Owners were asked to submit at least 7 grams of fresh faeces, which were collected, examined for the eventual presence of proglottids and stored at +4°C.

Laboratory analyses
All collected material was analyzed at the University laboratories of the 13 study centers.
Material collected with ea combs was examined under a stereomicroscope and the presence of ea/ ea debris recorded. Faeces were examined for the presence of proglottids and identi ed according to [15].
Mini-FLOTAC copromicroscopic examination was carried out on 2 g of faeces in 18 ml of NaCl oating solution (s.g 1200) according to the protocol described in [7]. Minimum/maximum eggs/oocysts/cyst per gram of feces (EPG/OPG/CPG) were calculated. The Baermann test was carried out on 5 g of faeces and examined approximately 12 hours later, according to [16].
Study center reference personnel was asked to register with the Castor ® EDC ® database [19], managed by the study monitor. Each reference personnel had her/his own login credentials. Results were transcribed into the database, preferably within several days of receipt and analyses.
Relationships between infection and the variables ("predictors") was analyzed by multivariable regression analysis applying a stepwise backward elimination methods (IBM SPSS Statistics for Macintosh, Version 27.0.). Statistical signi cance was set at α = 0.05.

Study population
Severe restrictions on movement/activity were put into place to contain the SARS-CoV-2 pandemic (March-2020 "lockdown"), which resulted in a decrease/lack of cat enrollment on the part of many centers from March 2020 to May 2020 leading to an extension of the study for a further 2 months. A total of 987 cats were enrolled.
Cats were evenly distributed regarding sex. Approximately half the study population (47.3%) was within the age range of 1-5 years, with the remaining evenly distributed between < 1 year (28.1%) and > 5 years of age (24.6%). Over 40% of enrolled cats were from Southern Italy and 69.2% were privately-owned cats. Over 75.8% of the study population lived predominantly outdoor/exclusively outdoor (Table 1).
Most cats, including privately owned animals, had not received anti-parasitic treatment in the year before enrollment. Overall, 539/987 (54.6%) cats from the present study were infected with one or more parasites. Moreover, 13.7% (135/987) had at least two endoparasites and 7.4% (73/987) had at least two arthropod infestations.
Of the 35.9% cats positive for any GI or BP nematodes, 20.1% were female and 15.8% were male. Of the female cats analyzed, 40.0% were positive for endoparasite infection, while of the male cats analyzed, 31.7% showed endoparasites and this difference was statistically signi cant (P=0.007). In addition, when compared to males, females had signi cantly higher prevalence values for T. cati (28.5% vs. 22.8%; P =0.04) and hookworms (13.5% vs. 6.3%; P <0.001).
Coccidiosis was more prevalent in younger cats, as is well known (20.6%). Prevalence of endoparasite infection was directly associated with the frequency of outdoor access. Cats with an exclusively outdoor lifestyle had signi cantly higher infection rates for A. abstrusus (14.5%; P <0.001) compared to cats living predominantly outdoors or predominantly indoors (5.4% and 2.5%, respectively). Cats with a predominantly/exclusively outdoor lifestyle had signi cantly higher prevalence values for T. cati (P =0.02) and hookworms (P < 0.001). Cats residing in the areas of Southern Italy had signi cantly higher prevalence values for T. cati (P <0.001), hookworms (P <0.001) and A. abstrusus (P <0.00).
Monthly prevalence throughout the study was variable (Fig. 2), yet there was no month in which parasites were not observed.
Of the total cat population analysed, prevalence values for ectoparasites were comparable between males (17.3%) and females (18.3%). Of females analysed, 36.6% were infected and of males analysed, 34.8% had ectoparasites. Overall prevalence of ea infestation for the 987 cats recruited was of 14.5% in females vs. 14.9% in males, and for O. cynotis 5.7% vs. 4.2%. Considering gender speci cally, 28.9% of examined females were infected with eas and 11.3% with O. cynotis, while 29.9% and 8.3% of males were infected, respectively with the two ectoparasites.
Monthly prevalence throughout the study was variable (Fig. 4). Only 23.8% of the cats had received at least one treatment against endoparasites in the past year, while only 33.6% of the cats had received treatment against ectoparasites in the past year.

Risk factors for endo-ectoparasites infestation
Signi cant risk factors as determined from univariate analysis were entered in the multivariable logistic regression model, to address possible confounding factors and to compute adjusted odds ratios. Tables 3 and 4 report results of multivariate analysis, which considered overall prevalence of endoparasite infection, overall prevalence of ectoparasite infection, and prevalence of the most common endoparasites (T. cati, hookworms and A. abstrusus) and ectoparasites ( eas and O. cynotis) as dependent variables and sex, age, provenance, lifestyle, geographical area and anti-parasitic treatment as predictors.

Discussion
The study provides a comprehensive look at the endo-and ectoparasites affecting Italian cats, throughout a 15-month study period. Even though monthly recruitment was brusquely interrupted due to the SARS-CoV-2 pandemic, nearly 1,000 cats were analyzed.
Importantly, laboratory analyses were carried out according to standardized protocols which were followed by all centers, thus reducing the risk of variability associated with different test sensitivities/speci cities.
The present study also applied univariate and multivariate analyses to evaluate overall risk for endoparasites or ectoparasites and for the most common helminths and arthropods observed.
Results show that feline endo-and ecto-parasites are widespread in Italy, with varying prevalence across the different regions. Approximately 55.0% (539/987) of cats from the present study were infected with at least one internal or external parasite. This compares well with results from [1] that evaluated parasite infection of the European owned cat population, demonstrating that more than half (50.7%) of the cats studied were infected with one or more endo-and/or ectoparasites.
Among gastro-intestinal helminths, T. cati was the most frequently found (25.6% of enrolled cats). This is higher than that reported by a previous Italian multicenter study [4], which highlighted a prevalence of 21.6%, and also higher than the mean European prevalence value reported in 2017 by [2] (14.5%). The prevalence is, however, in line with other surveys conducted in Italy [5,6]. In the present study, risk for T. cati infection included age (< 5 years of age), an exclusively outdoor lifestyle and living in Southern Italy. Pre-and perinatal transmission and age immunity are well-known for Toxocara spp., while outdoor access favors exposure to both highly resistant eggs contaminating the environment and to paratenic hosts [20].Warmer climatic conditions in Southern Italy and islands likely seems to increase the presence and persistence of infective stages of the parasite.
Surprisingly, hookworms were the second most frequent group of nematodes diagnosed in the study population (9.9%). Giannelli et al. [2] reported a mean prevalence of 4.5%, while [4] reported a prevalence of 4.9%. In the present study, hookworm infection was associated with gender (females were at increased risk), predominantly outdoor access, living in Southern Italy and lack of anthelmintic treatment. Age was not a signi cant risk predictor. Indeed, it is assumed that there is no transmammary transmission of hookworms from the queen to her kittens [21] As mentioned above, warmer climatic conditions in Southern Italy may increase the presence and persistence of infective stages of hookworms. For transmission to occur, hookworms need to develop into infective larvae in the soil from eggs passed in the host's stool and higher temperature and humidity (tropical and subtropical climates) provide an adequate environment for this growth stage [22].
The feline lungworm A. abstrusus was present in 7.7% of analysed cats. Mean prevalence in Europe according to [2] was 8.2%, while recent data from Italy [4] reported a prevalence of 10.3%. Multivariate analysis indicated exclusively outdoor lifestyle, living in Southern Italy and lack of anthelmintic treatment as signi cant risk factors for A. abstrusus. Outdoor access has been reported previously as an important risk factor for A. abstrusus [23]. While the geographical distribution of feline lungworms tends to be patchy but stable in endemic hotspots [2], interpretation of geographical location as a risk factor should be done with caution and any geographic location reporting autochthonous circulation of the parasite should be considered potentially endemic. Traversa et al. [4] reported a 20.0% prevalence of A. abstrusus in Piedmont, while in the present study only 1.2% of cats were infected. Giannelli et al. [2] reported that 16.7% of cats from the province of Bari were infected with A. abstrusus, while in the present study the prevalence was 2.4%. Values from provinces of Sassari (SS) and Messina (ME), on the other hand, were higher in the present study (20.9% and 22.4%, respectively) ( Table 2), compared to data reported by [2] (11.6% and 15.3%, respectively), but lower than that reported by [24] in a previous study in Sardinia. Interestingly, univariate analysis showed cats > 5 years of age had signi cantly higher prevalence for A. abstrusus, but age was not con rmed as a risk factor following multivariate evaluation. As expected, larvae of T. brevior were found mostly in cats from Southern regions. Nevertheless, it is worth mentioning that, in the present study, this potentially fatal metastrongyloid was also found in two cats in Northern Italy, indicating an apparent northward geographical expansion.
Mini-FLOTAC in combination with Fill-FLOTAC was shown to be user-friendly and safe, with a wide diagnostic range. These features are particularly useful for monitoring and control programs in which large numbers of fecal samples need to be processed rapidly and safely. The harmonized use of the Mini-FLOTAC technique allowed the qualitative and quantitative analysis of parasite load without the need for specialized equipment.
Fleas were the most common ectoparasite found in the present study (29.4%). Cooper et al. [25] reported similar prevalence values in a recent nationwide study in the United Kingdom. Beugnet et al. [1] reported prevalence values ranging from 3.6% in Bari to 31.4% in Naples. None of the study centers in the present study reported values less than 14.0%. Multivariate analysis showed that infestation was associated with young age (< 1 year), living in a colony, predominantly/exclusively outdoor lifestyle, living in Central and Southern Italy and lack of ectoparasitic treatment. Cooper et al. [25] have reported geographical differences (prevalence declining from South to North in UK) and no treatment as signi cant predictors of risk for ea infestation. Beugnet et al. [1] identi ed outdoor access as the only risk factor in multivariate analysis.
The ear mite O. cynotis was present in 9.8% of enrolled cats. Beugnet et al. [1] reported prevalence values of 40.3% in cats from Bari and 21.8% in cats from the area of Naples. In Tuscany (central Italy), O. cynotis was identi ed in 66.1% cats with otitis externa [26]. Age < 1 year, living in a colony, having a predominantly outdoor lifestyle and coming from Central Italy were all factors identi ed as increasing risk of ear mite infection in cats. O. cynotis is transmitted by direct contact and is highly contagious. Young cats are more playful and likely have more direct contact with other cats.
The main limitation of the present study is the potential effect of bias, based on inclusion criteria. Indeed, similar to a previous multicenter study [1], here only cats that had not received antiparasitic treatment in the previous three months were enrolled. Furthermore, outdoor access was necessary for enrolment.

Conclusions
The results of this study highlight the fact that both ecto-and endoparasites are still common in cats throughout Italy. Interestingly, of the 239 cats with a predominantly indoor lifestyle, 31.8% were affected by endo-ectoparasites, suggesting that parasiticide treatment is more important than lifestyle. Therefore, given the zoonotic consideration and the clinical importance, it is strongly advisable to promote effective and regular parasite control in cats, with adequate frequencies of treatment for both internal and external parasites.
It is interesting to note that there was no month in which endo-ectoparasites could not be found, suggesting that cats can be infected all year round. This would imply that parasite infection should not be considered seasonal, but that control should be yearround. However, only 23.8% of the cats had received at least one treatment against endoparasites in the past year, while only 33.6% of the cats had received treatment against ectoparasites in the past year.
The European Council for the Control of Companion Animal Parasites (ESCCAP) recommends "year-round, life-long" parasite control. Many privately-owned cats spend a signi cant amount of time outdoors and are exposed to parasites. Practitioners need to inform their clients of the risks and recommend periodic anti-parasitic treatment.
Interestingly, Southern Italy continues to show higher prevalence of parasite infection in cats. This may be due to climatic, social or economic factors and practitioners working in these areas should be particularly attentive. The cats' owners signed an informed consent authorizing the use of faeces and hair for the study.

Consent for publication
Informed consent was obtained from all individual participants included in the study.

Figure 2
Endoparasite prevalence according to monthly evaluation.  Monthly prevalence of ectoparasite infections.

Supplementary Files
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