Seasonal activity of ticks infesting domestic dogs in Bejaia province, Northern Algeria

This epidemiological study aimed to determine the species of tick infestation in dogs, their prevalence and dynamic in the Bejaia province, northeastern Algeria. A total of 631 dogs were examined from different localities of the Bejaia province between March 2016 and February 2017. Of the 631 examined dogs, 15% were infested with one or more tick species. A total of 339 adult ticks were collected and identified, including 199 male tick species and 140 female tick species. Our results revealed that most of these were Rhipicephalus species, with Rhipicephalus sanguineus (51.32%) being the most prevalent followed by Rhipicephalus bursa (35.1%) and Rhipicephalus turanicus (12.98%). Ixodes ricinus represented only 0.6% of all ticks collected. The highest infested seasons were spring (22.55%) and summer (22.54%) and the lowest infested seasons were autumn (8.62%) and winter ( 0.9%). There is no significant difference between the sex of the animal and the prevalence of infestation (p = 0.837). Also, the prevalence of infestation by ticks in young animals was higher than that in adult animals (p = 0.550). A significant difference between the prevalence of infestation and animal breed was observed (p = 0.042). This study is the first epidemiological investigation conducted on the prevalence of hard ticks infesting domestic dogs in Bejaia (northeastern Algeria) based on conventional methods. It is therefore necessary to implement an effective tick control strategy during infestation periods in order to prevent vector-borne diseases.


Introduction
After mosquitoes, ticks are the second most important obligate haematophagous arthropods that parasitise all classes of vertebrates for their blood meal in almost all regions of the world, particularly in Africa (Laamri et al. 2012;Xhaxhiu et al. 2009). They can also crucially transmit to animals, especially dogs, a large number of protozoa and bacteria, such as Babesia, Theileria and Anaplasma spp. (Gray et al. 2013;Marquez-Jimenez et al. 2005). The seasonal dynamics of ticks is likely to affect the transmission of pathogens. Several ecological factors can influence the survival and development of ticks, especially temperature, relative humidity and vegetation cover (Sahibi & Rhalem 2007). All tick species are significant disease vectors and the increased incidence of these diseases is mainly attributed to climate change that affects ticks directly or indirectly (Gray et al. 2009). Ticks are highly climate-sensitive arthropods, and all stages of their life cycle depend on a complex combination of climatic variables. The presence of hosts and vegetation greatly modulate the dynamics of their populations. However, vegetation is a major modifier of local climatic conditions, to which ticks must adapt for their development and survival (Estrada-Peña, Ayllón & De La Fuente 2012).
Dogs are the most commonly owned companion pets worldwide (Moriello 2003). They are the most successful canids, adapted to human habituation, which contribute to the physical, social and emotional well-being of their owners (Dohoo et al. 1998). It is possible that dogs carry ticks in the domestic environment and transmit these to humans, which may constitute a major concern for public health (Dantas-Torres, Chomel & Otranto 2012).
In Algeria, very few studies have been conducted on the vectorial role of ticks that infest dogs, except the inventory carried out by Matallah et al. (2013). In terms of biodiversity and specific biology, Ixodidea fauna is not sufficiently known in Algeria (Meddour & Meddour 2006). Because of certain geographical specifications and the probable presence of different types of ticks infesting companion animals, epidemiology studies of ticks in dogs are extremely important to plan the approaches of pest management. This study aimed at determining the species of tick infestation in dogs, their prevalence and dynamics by performing an epidemiological study in the Bejaia province (northeastern Algeria).

Study area and dogs
The study was carried out in the Bejaia province of Algeria (36°43'N, 5°04'E) ( Figure 1) from March 2016 to February 2017. The province has four distinct seasons: winter (January to March), spring (April to June), summer (July to September) and autumn (October to December). The annual rainfall in the region during the study period ranged from 679 mm to 821 mm. The mean maximum summer temperature was 29.9 °C (August) and the mean minimum winter temperature was 6.4 °C (January) during the study period (Table 1).
A total of 631 dogs were selected randomly from different habitats (home and farmhouse) and localities of the Bejaia province. All dogs were presented to a veterinary clinic for different reasons (care, vaccinations, etc.). A dermatological examination was performed by veterinary practitioners and all observations were recorded for each dog examined throughout the study. A complete examination of the skin, visually and by palpation, was done for the presence of ticks. The age of the animals ranged between a few days and over 15 years, with mixed breeds.

Tick collection and identification
All ticks were removed carefully to ensure that the mouthparts remained intact. The ticks collected were preserved in individually labelled plastic containers containing 70% ethanol. Tick identification was carried out using standard methods at the Laboratory of Animal Biology, University of Bejaia. Each tick was identified using a stereomicroscope (MOTIC, ST-37C-2LOO) according to the standard morphological identification keys (Meddour & Meddour 2006;Walker et al. 2014).

Statistics analysis
Prevalence was calculated as the ratio between the number of infested dogs and the total number of examined dogs. Abundance was determined as the ratio between the total number of parasitic species and the total number of examined dogs. Infestation intensity was calculated as the ratio between the total number of parasitic species in hosts and the number of infested hosts. Statistical analyses were carried out using the R software version 3.4.4 (http://www.R-project.org/). Tick infestation was analysed using the following factors of variation: sex (male and female), age (young: ≤ 12 months; adult: > 1 year), breed (German Shepherd, Rottweiler, American Staffordshire Terrier, Belgian Shepherd, Dogo Argentino, French Pointer and others) and season (spring, summer, autumn and winter). Statistical analysis was performed using a negative binomial General Linear Model (function 'glm.nb' in library 'MASS' in R). Tukey's post-hoc test was performed using the 'glht' function from the multcomp package. The values were statistically different when the p-value was < 0.05.

Ethical considerations
Ethical clearance to conduct the study was obtained from the scientific committee of the Faculty of Nature and Life Sciences, University of Bejaia.

Results
Of the 631 examined dogs, 15% were infested with one or more tick species. A total of 339 mature ticks were collected and identified, including 199 male and 140 female tick species. The overall prevalence of infestation was found to be 15% (94/631) during clinical examination.

Province of Bejaia
In this study, two tick genera, Rhipicephalus and Ixodes, were identified based on the external morphological characteristics (Table 2). Our results revealed that among the Rhipicephalus species, Rhipicephalus sanguineus was the most prevalent (51.32%), followed by R. bursa (35.1%) and R. turanicus (12.98%). Ixodes ricinus only represented 0.6% of all ticks collected. The ears and neck are the preferred attachment sites of ticks, with a prevalence of 55.8% and 22.2%, respectively. Mixed infestations with more than one tick species were recorded in the majority of dogs (Table 3). Table 4 illustrates the seasonal variation of tick infestation in dogs in the Bejaia province. The total tick prevalence peaked during spring and summer (22.55% and 22.54%, respectively) and the lowest prevalence occurred during winter (0.9%) (p < 0.001). The abundance and high intensity of ticks were observed in spring (1.04 and 4.58, respectively) and summer (0.61 and 2.71, respectively), but the lowest abundance and intensity were observed in winter (2.00 and 0.01, respectively) (p < 0.05). The monthly variation in the prevalence of infested animals because of R. sanguineus, R. bursa, R. turanicus and I. ricinus is shown in Figure 2. The prevalence rates recorded of infested dogs by R. sanguineus, R. bursa and R. turanicus were very high during April and May. As regards to I. ricinus, a prevalence rate was observed only in December.
The variation of prevalence of infestation by sex, age and breed is shown in Table 5. There was no significant difference between the sex of the animal and the prevalence of infestation (p = 0.837) and the age of the animal and the prevalence of infestation (p = 0.550). Conversely, the prevalence of infestation by ticks in young animals (≤ 1 year of age) was higher than that in adult animals (> 1 year of age) (p = 0.550). Tick prevalence differed significantly between dog breeds (p = 0.042).

Discussion
Ectoparasitic infestation is widespread in wild and domestic animals worldwide, several of which are responsible for diseases (Krčmar et al. 2014;Ranju et al. 2012      This study is the first on ticks infesting domestic dogs in the Bejaia province (northeastern Algeria). Our results revealed that the domestic dogs are infested by a variety of tick species, with one or more tick species per infested dog as described previously (Ebrahimzade, Fattahi & Mohammad 2016;Estrada-Peña et al. 2017;Latrofa et al. 2017;Maurelli et al. 2018). The overall prevalence of infestation was slightly low, which could be a result of difficulties in detecting smaller tick life stages (larvae and nymphs) during clinical examination. Studies performed in different countries have shown that the prevalence of infestation by ticks is significantly variable. The prevalence observed in the current study is higher compared to studies from Iran (8.6%) (Ebrahimzade, Fattahi & Mohammad 2016) and Albania (3.5%) (Kumsa & Mekonnen 2011). However, it is substantially lower than that reported by Matallah et al. (2013) in the Souk-Ahras and El-Kala areas, northeastern Algeria (63% and 37 %, respectively). The low rate observed in this study may be explained by the fact that dogs are better maintained by the use of acaricidal treatments. The prevalence rates suggests that these ticks present a real major health problem for domestic dogs and their owners as supported by several studies (Kumsa & Mekonnen 2011;Rinaldi et al. 2007).
Based on the identification keys from morphological characteristics that are approved for African countries, the current results describe four tick species, with a predominance R. sanguineus. This finding is in agreement with the previous reports (Benredjem et al. 2014;Bessas et al. 2016;Dahmani et al. 2015;Leulmi et al. 2016). A similar finding of the predominance of this tick species in infested dogs has been reported by Matallah et al. (2013) Kumsa and Mekonnen (2011) identified two species of ticks, namely, Amblyomma spp. and Haemaphysalis leachi. The variation reported in previous studies might be attributed to different factors, such as geographical locations, climatic conditions and management practices (Krčmar et al. 2014). Additionally, indirect effects of climate change will impact the number of infected ticks by affecting vegetation (Gray et al. 2009). The correlation between positive cases of vector-borne disease and their geographic distribution, as well as potential risk factors (age, sex, breed, type of dog, habitat and prophylactic treatments), was evaluated previously (Mircean et al. 2012). Also, Lindgren, Tälleklin and Polfeldt (2000) concluded that the relatively mild climate of the 1990s in Sweden was probably one of the primary reasons for the observed increase in density and geographic range of I. ricinus ticks. In addition, similar preferred attachment sites of ticks in dogs were found in previous studies (Foldvari & Farkas 2005;Krčmar et al. 2014) compared to our data.
Rhipicephalus sanguineus, known as the kennel tick, is the most widespread tick in dogs; however, it can also be found in cattle (Walker et al. 2014  . Our result revealed two cases of I. ricinus ticks collected from companion dogs in the Bejaia area, Algeria. In North Africa, it is known that the ixodid tick species infest livestock, and their adults are present in large numbers only on livestock (Walker et al. 2014). However, I. ricinus has been observed in more than 300 host species, including mammals, birds and reptiles (Gern & Humair 2002). It is considered as a potential vector of many disease agents (Farkas 2002). This result could be explained by the fact that dogs would have been infested in the wild. According to Walker et al. (2014), all stages of the development of I. ricinus climb in vegetation for transfer to the host. Moreover, the most favourable conditions for the development of I. ricinus are in temperatures that are relatively cold and high levels of humidity. Note that the only cases of I. ricinus was found in December.
In this survey, the Rhipicephalus species collected from companion dogs has shown mainly spring activity, while I. ricinus has a winter activity. This could be ascribed to a variety of climatic conditions in this study region. It has been reported that R. sanguineus was present in various Maghreb countries of different bioclimatic zones, in which the adult ticks have a seasonal activity from March to November, with a peak activity in May, and it was absent in winter (Bouattour 2002). Moreover, in other studies, the presence of R. sanguineus was reported from June to September (Leulmi 2012). In Morocco, Morel (2000) revealed that the seasonal dynamic of R. bursa was unimodal, with a peak in activity during the warm season ranging from March to September; this finding is similar to the results of the present study. Likewise, the R. turanicus tick species appears in March and disappears in July (Tsatsaris et al. 2016). As shown in Figure 2, R. turanicus has been collected between April and November, with a peak infestation in April and May. Concerning the activity period of I. ricinus, it agrees with the results reported previously, that is, autumn-winter (Bouattour, Darghouth & Daoued 1999). In contrast, I. ricinus developed in bimodal mode in the temperate countries, with intense and low activity peaks during spring and autumn, respectively. In the UK, the maximum abundance of I. ricinus has been observed in April and May and their stages show a lesser resurgence in numbers in late summer (Dobson & Randolph 2011).
In the present study, the overall prevalence of dogs infested by different male tick species was higher than female tick species; however, this was not statistically significant (p = 0.837). Similarly, Ebrahimzade, Fattahi and Mohammad (2016) reported no statistically significant difference in the tick burden between the sexes living in the same ecological environments. In addition, Rodriguez-Vivas et al. (2003) suggested that both sexes are susceptible to ectoparasite infestation. In contrast, Mosallanejad et al. (2011) found a significant difference between male and female tick species infested by ectoparasites (35.82% vs. 20.33%, respectively).
The proportion of infestation caused by the total number of ticks varied between two age groups of dogs. It was the highest in young and the lowest in adult dogs (p = 0.55). Studies have shown that the susceptibility of tick infestation is greater in young animals than in adult animals (Moghaddar, Shorigeh & Gastrodashty 2001;Raut et al. 2006). The influence of age has also been reported by a study in Tunisia, where the frequency of infestation of adult cattle was higher than that of young animals (Bouattour 2001). These results could be because of the immunity system of infected animals which is less developed at an early age (Dillard, Saari & Anttila 2007).
There is a significant difference between the breed of animal and the prevalence of tick infestation (p = 0.042). In contrast, no significant effect to bovine (Benchikh-Elfegoun et al. 2007) and dog (Lorusso et al. 2010) breeds on tick infestation was observed in other studies. On the other hand, a previous study reported that dog breeds have a direct influence on the infestation rate (Silveira, Passos & Ribeiro 2009). Statistical analysis revealed that German Shepherd breeds are the most infested compared to other breeds examined in this study. Smith et al. (2011) found that dogs with medium hair length were twice as likely to have ticks than dogs with short hair (p < 0.001). Dogs characterised by long hair could provide a conducive environment for tick survival compared to shorthaired dogs. It is easy to detect and remove the ticks in the short-haired dogs than those with long hair. Also, shorthaired dogs may be more effective in self-grooming and may remove ticks themselves.

Conclusion
This study is the first epidemiological investigation conducted on the species of ticks, their prevalence and dynamic in infesting domestic dogs in the Bejaia province (northeastern Algeria) based on conventional methods. Our finding showed the presence of four species infesting dogs, with R. sanguineus being the most abundant. The low frequency of ticks in the study area raises concerns about the endemic presence of certain diseases transmitted to dogs. It is therefore necessary to implement an effective tick control strategy during infestation periods in order to prevent vector-borne diseases. Also it is recommended that studies regarding the dynamics of hard ticks in other regions should be conducted to complement the knowledge of Ixodidea fauna in Algeria.