Influence of Agro-climatic Factors on the Prevalence of Ixodid Ticks on Cattle in Telangana State, India

Livestock rearing is one of the most important economic activities in rural areas of the country, which accounts for about 27.2 and 4.1 per cent in agriculture and national GDP, respectively (Islam et al., 2016).

Cattle are the main source of animal protein apart from milk, providing meat, hides, draft power and their dung is used to increase soil fertility. India accounts for a significant share of worlds livestock resources nearly 16.5% of cattle, 16.3% goats and sheep 5.7%. Although India is ranking first in the total milk production, the tropical livestock productivity is quite low (Pino, 1981) because, of the neglected management and poor health of animals due to various factors including diseases as well as their transmitting agents (ectoparasites). Among ectoparasites, ixodid ticks are important blood-feeding parasites (Furman and Loomis, 1984).

Ticks either cause direct losses through tick worry, anaemia, reduction in live weight gain, dermatitis, low milk yield, down grading the quality of hides, producing toxins causing paralysis or indirectly through the transmission of various disease causative etiological agents. viz., Theileriaannulata, T. buffeli, T. lestocardi (hirci), Babesia bigemina, B. motasi, Anaplasma marginale, Ehrlichia bovis and E. phagocytophila (Ghosh et al., 2007). Both cattle and buffaloes are reared together, the number of ixodid species reported from cattle are significantly more (Ghosh et al., 2006). Annual global production losses due to tick and tick borne diseases was estimated as USD 22 billion (Lew-Tabor and Valle, 2016).

Although species of ticks and tick borne diseases (TBDs) differ among ecological regions, their impact on cattle production depends on region, species involved, agents, host population, socioeconomic and technological  advances adopted in control  measures  (Solis 1991). For an effective control measure, it is necessary to investigate various epidemiological factors, which determine the frequency and distribution of ticks. Incidence and prevalence of Ixodid ticks were reported earlier from different parts of the country viz. Gujarat, Haryana, Kerala, Maharashtra, Rajasthan, Punjab, Tamil Nadu, Uttarakhand, Uttar Pradesh and West Bengal (Sanyal and De, 2005; Kaur et al., 2015) except from Telangana, India.
 

Study location
 
Telangana is a newly formed state in the Southern region of India spread over an areaof 114,840 km2 (44,300 sq. m) and situated between 16°-20°N latitude and 77°-82° E longitude (Table 1).


 
Study design
 
The cross sectional study was designed to investigate the distribution of ticks infesting cattle in Telangana state, where intensive agricultural and animal husbandryactivities are practiced. Cattle from six erstwhile districts of Telangana (Fig 1) were selected from 3 agro climatic zones along with season during the period from March 2019 to February 2020.



Some of the ticks were collected from representative cattle of each district with the help of blunt forceps and brush from different body parts of the cattle without damaging their mouth parts (Fig 2). After collection, the ticks containing vials were properly labelled with the details of zone, age, sex of the animal, date of collection etc. The ticks were brought to the Laboratory of Veterinary Parasitology, College of Veterinary Science, Rajendranagar in 70% alcohol (preservative) for identification using stereomicroscope. The identification was done by standard keys of Souls by (1982) and Walker et al., (2003).


  
Statistical analysis
 
The epidemiological data obtained from the study was analyzed by chi-square test in statistical software SPSS 16.0. The results with a greater number of proportions were analysed by Marascuilo test as described by Marascuilo and McSweeney (1967).

The epidemiological studies indicated an overall prevalence of 63.4% (5625/8872) of tick infestation in Telangana state (Table 2).



Previous studies conducted indifferent parts of India reported an overall prevalence of tick infestation ranging from 22.4 to 68.2%. The high prevalence of tick infestation similar to the present study was reported from Punjab (58.06%), Lucknow (59.11%), West Bengal (41.93%), TamilNadu (68.2%) states of India by Singh and Rath (2013), Kaur et al. (2017), Debbarma et al. (2018) and Balasubramanian  et al. (2019), respectively. The higher rate of tick prevalence in cattle of Telangana might be due to the climatic conditions that are highly conducive for the development and propagation of Ixodid ticks as evidenced by the meteriological data and also due to an increased rearing of cross bred cattle (Haque et al., 2011). In contrast to the present results, comparatively, a lower rate of prevalence was reported by Shyma et al. (2013) in cattle of Kerala (22.4%).  The variation in the rate of prevalence of tick infestation in the study area and different parts of world could be due to the variation in geographical conditions of regions under study in addition to the other factors like host susceptibility, host density, grazing habits and managemental practices that influenced the distribution and propagation of ticks as opined by Aboma et al., (2017).
 
Zone wise prevalence of Ixodid ticks
 
A total of 8872 cattle were examined from three major agro-climatic zones of Telangana viz., central zone (Khammam and Warangal Districts), north zone (Karimnagar and Nizamabad Districts) and southern zone (Mahaboobnagar and Rangareddy Districts). Higher rate of tick infestation was found on cattle in central zone (78.05%) than northern zone (71.3%) and least in southern zone (51.9%) (Table 3). However, multiple proportions of Merascuilo test indicated significantly higher incidence in central zone and lowest in southern zone at a critical value of 5.9.



Higher prevalence recorded in central zone could be due to the typically tropical, rainy and somewhat humid climate and suitable ambient temperature. This zone receives an annual rainfall ranging from 1027 to 1032 mm and about 88.03% of total rainfall is received during south west monsoon only and humidity also reach 70-90%. Among the total land 40.6% were under irrigation which favours the growth of herb, shrub and grass and created a favourable sheltering place for ticks throughout the year as opined by MacLeod (1970). Whereas annual rainfall below 700 mm, dry and arid type of climate with red sandy soils and only 14% of the lands under irrigation without any forest cover, tree clad or vegetated areas in southern zone resulted in less humidity with resultant shrinkage of eggs, failure of hatching eggs lead to less prevalence of ticks compared to other two zones.

Though numerically the percent of tick infestation is higher in central zone it was not significantly (P≤0.05) comparable to northern zone. However, the tick infestation in central and northern zones were significantly (P≤0.05) higher than that of southern zone. The reason could be similar type of semi-arid climate in central and north zones compared to arid climate in southern zone. Similarly, Singh et al. (2013) recorded highest prevalence of tick infestation in sub mountain undulating plain region (98.4%) compared to that of other regions and established correlation between tick prevalence and annual rainfall and concluded a low tick prevalence with a decrease in annual rainfall. On contrary, Ghafar et al. (2020) reported higher tick prevalence in sandy desert than inirrigated plains.
 
District wise prevalence
 
Among the six districts of Telangana, the prevalence was significantly (P≤0.05) higher in Khammam (79.7%) followed by Warangal (76.2%), Nizamabad (73.7%), Karimnagar (69.4%), Mahaboobnagar (55.8%) and was minimum in Rangareddy (47.5%) districts (Table 3). Reason being the Khammam district was at high altitude, tribal zone and most of the land covered by forest and water bodies and Nizamabad district is situated at a considerable altitude from the sea-coast which holds suitable humidity (TSDPS and DES, 2021). The forests are mainly spread over the central part of both districts. These are Southern tropical dry deciduous forests and also help to render the climate more equitable for propagation of vectors. The cross bred population was also high in these districts which are more susceptible to tick infestation. Comparatively low prevalence of tick infestation in Karimnagar could be due to the improved husbandry practices followed in that area and awareness of farmers about their control.

In southern zone, the prevalence of tick infestation was high in Mahaboobnagar district (55.8%) compared to Rangareddy district (47.5%). Though rainfall in this area is scarce, the Krishna and Tungabhadra rivers were flowing through the southern Telangana are responsible for soil moisture in Mahaboobnagar leading to high prevalence. Rangareddy district located in the central part of Deccan plateau which is completely dry with arid type of climate and with less irrigated facilities showed comparatively less prevalence.
 
Season wise prevalence
 
Ticks from different districts of Telangana were collected throughout the year to understand the correlation between seasons and population dynamics of ticks. The study period was divided into three seasons viz. summer, monsoon and winter. The prevalence of tick infestation was significantly (p<0.05) higher in monsoon (71.91%) followed by summer (66.14%) and least in winter (52.21%). Multiple proportions of merascuilo test indicated significant (P<0.05) difference among the three seasons being highest in monsoon at a critical value of 5.9 (Table 4).



Ambient temperature and higher atmospheric humidity and microclimate of grazing lands in rainy season were more conducive for the feeding, growth, breeding, development and propagation of ticks (Ghai et al., 2008). The decreased prevalence of ticks in winter season could be due to their ability to protect themselves from adverse environmental conditions by entering into diapause leading to increased resistance to environmental extremes and reduced behavioural activity (Vatsya et al., 2007). Temperature, amount of bright sunshine hours, rainfall with relative humidity have been correlated either negatively or positively with questing behaviour of ticks leading to behavioural diapause involving temporary suppression of host seeking or attachment by unfed ticks (Belozerov, 1982). Ticks avoid questing at unfavourable times of the year, such as mid-summer when the temperature is too high and too low humidity or winter. Ticks has the capacity to convert its body weight into egg mass at certain temperature and accordingly egg production was seized at below 10°C (Gray et al. 2016). Similar findings were made by Vatsya et al (2007). who reported significantly highest prevalence of ticks in monsoon (54.86%) when compared to summer (41.04%) and winter (23.93%) seasons and opined that, although the animals were infested with ticks thought the year, their numbers increased following rains indicating the rainfall as an important macroclimatic factor. The other authors like Debbarma et al. (2018), Singh et al. (2013) also reported high tick prevalence in rainy season followed by summer and least in winter.

The high level of tick infestation on cattle of Telangana state is suggestive of suitable environmental conditions for the propagation of ticks and tick born diseases and farmers should be advised to keep the animals under check at regular intervals and urgent need to develop strategic region specific schedule of tick control programmes.

The authors thankfully acknowledge P.V. Narsimharao Telangana Veterinary University, Rajendranagar, Hyderabad, Telangana, India for financial support and providing necessary facilities to carry out the research work.

No potential conflict of interest was reported by any authors.