Prevalence of haemoprotozoan infections in cattle across different agro-climatic zones of Hassan district, Karnataka

Introduction

Haemoprotozoan infections constitute a major constraint to cattle health and productivity worldwide, particularly in tropical and subtropical regions where vector populations thrive throughout the year. Among these, Theileria, Babesia, and Anaplasma species are of considerable veterinary importance due to their widespread occurrence and significant economic impact on the livestock sector. These infections are primarily transmitted by ticks and lead to clinical manifestations such as fever, anemia, reduced milk yield, weight loss, and in severe cases, mortality, thereby affecting both subsistence and commercial dairy farming systems (Maharana et al., 2016) [11] . India, with its diverse agro-climatic conditions, provides a favorable environment for the survival and proliferation of tick vectors, thereby facilitating the endemicity of haemoprotozoan diseases. Several studies from different parts of India have reported variable prevalence patterns influenced by ecological and management factors (Singh et al., 2012; Maharana et al., 2016; Sharma et al., 2021) [14, 11 13] . Karnataka, particularly the southern region, is characterized by heterogeneous agro-climatic zones ranging from dry to hilly terrains, which may differentially influence disease distribution and transmission patterns (Ananda et al., 2009; Krishnamurthy et al., 2016; Mankani et al., 2024) [2,9,12] . Host-related factors such as age, sex, and breed also play a critical role in determining susceptibility to haemoprotozoan infections. Adult cattle are often reported to exhibit higher infection rates, possibly due to prolonged exposure to tick infestation, whereas younger animals may show varying degrees of resistance or subclinical infection. Similarly, crossbred cattle are generally considered more susceptible compared to indigenous breeds due to differences in genetic resistance and adaptability to local environmental conditions (Kaur, et al., 2021) [8] . Despite the recognized importance of haemoprotozoan diseases, there is limited epidemiological data available for districts like Hassan in Karnataka, where livestock farming is an integral component of rural livelihoods. Understanding the prevalence pattern across different agroclimatic zones, along with associated host risk factors, is essential for designing targeted control strategies and improving animal health management. Therefore, the present study was undertaken to determine the prevalence of haemoprotozoan infections in cattle across different agro-climatic zones of Hassan district, Karnataka, with particular emphasis on age, sex, and breed-related variations.

Materials and Methods

Study Area: The study was conducted in Hassan district of Karnataka, comprising four agro-climatic zones, viz., Central Dry, Southern Dry, Southern Transition and Hilly zones. A total of 200 blood samples were collected from cattle following a cluster sampling method, with 50 samples obtained from randomly selected in each agroclimatic zone.

Sample Collection: Blood samples were collected aseptically from the jugular vein in ethylene diamine tetra acetic acid (EDTA)-coated vacutainer tubes and transported to the laboratory under chilled conditions. Thin blood smears were prepared immediately after sample collection using clean, grease-free glass slides.

Laboratory Examination:

The smears were air-dried at room temperature, fixed in absolute methanol for 2-3 minutes, and subsequently stained with Giemsa stain following standard protocols. After staining, the slides were gently washed with buffered water, air-dried, and examined under a light microscope. Microscopic examination was carried out under oil immersion using a 100× objective lens for the detection of haemoprotozoan parasites. Identification of parasites was carried out based on morphological characteristics as described by Benjamin (1998) [3] .

Statistical Analysis: Prevalence was calculated as percentage. Chi-square (χ²) test was used to determine the association between infection and variables such as zone, age, sex, and breed. A p-value < 0.05 was considered statistically significant.

Results and Discussions

A total of 200 cattle from four agro-climatic zones of Hassan district were screened for haemoprotozoan parasites. Theileria was the most prevalent parasite, detected in 41.5% of animals, followed by mixed infections (5%), Babesia (3.5%) and Anaplasma (1%) (Table 1, Figure 1). The dominance of Theileria in Hassan district aligns with the findings of Mankani et al. (2024) [12] , who reported Theileria annulata as the most frequent haemoprotozoan in cattle from the Hassan region of Karnataka. Similarly, Ganguly et al. (2017) [6] and Acharya et al. (2017) [1] also reports higher prevalence of Theileria from Haryana and Bhubaneswar.

Zone-wise, the Central dry zone recorded the highest Theileria prevalence (58%), whereas mixed infections were primarily seen in the Southern dry (8%) and Southern transition zones (12%). Babesia and Anaplasma infections were largely confined to the Southern transition zone. The observed significant differences in parasite prevalence among zones (χ², p < 0.05; superscripts in Table1, Fig. 1) indicate that agro-climatic factors, such as temperature, humidity, and tick vector abundance, play a major role in determining infection patterns, which is consistent with observations by several authors viz; Kaur, et al., 2021 [8] ; Kumar et al. 2016 [10] from different parts of India. Age-wise distribution revealed that adult cattle (>1-3 years) were most susceptible to Theileria (34%) and mixed infections (5%), whereas younger animals (0-1 year) showed minimal infection (Table 1, Figure 1).Higher prevalence in older cattle agrees with reports by Sharma et al. (2021) [13] , who found that cumulative exposure to tick vectors increases susceptibility with age. These findings supports that older cattle are more susceptible with continuous tick exposure and carrier population in the field conditions. Slightly higher prevalence was noted in females compared to males, but these differences were not statistically significant. This observation concurs with findings of Farooq et al. (2019) [5] , and Ghosh et al. (2020) [7] , who also reported higher prevalence rate in females, the reason could be attributed due to physiological stress factors such as pregnancy, lactation, and hormonal influences etc. Breed-wise analysis indicated marginally higher infection rates in crossbred cattle compared to native breeds, particularly for Theileria and mixed infections. (Table 1, Figure 1).This aligns with the work of Subapriya et al. 2021 [15] ; Sharma et al. 2021 [13] ; Ghosh et al. 2020 [7] , who also noted that indigenous breeds often exhibit greater resistance to haemoprotozoan infections than crossbred animals, likely due to indigenous cattle possess better innate resistance to haemoprotozoan parasites, possibly due to genetic adaptation to local environmental and vector pressures. In Karnataka, multiple region-specific investigations have highlighted the endemic nature of these infections. For instance, studies in Shimoga reported an overall prevalence of 43.3%, with Theileria annulata being the predominant parasite, followed by Babesia bigemina and Anaplasma marginale (Krishnamurthy et al., 2016) [9] . Similarly, investigations in Mysore and adjoining districts (Mandya, Chamarajanagar, and Kodagu) revealed an overall prevalence of 40.22%, with a markedly higher occurrence of theileriosis compared to other haemoprotozoan infections (Dharanesha et al., 2017) [4] . Earlier reports from Bangalore North also demonstrated a higher prevalence of Theileria infections in crossbred cattle, particularly during monsoon seasons (Ananda et al., 2009) [2] . More recent observations from Hassan district further indicate a rising trend in haemoprotozoan infections, with Theileria accounting for the majority of cases, emphasizing the growing significance of these diseases in the region (Mankani et al. 2024) [12] .

Acknowledgement

AcknowledgementThe authors gratefully acknowledge the Karnataka Veterinary, Animal and Fishery Sciences University, Bidar and Veterinary College, Hassan for providing the necessary facilities to carry out this research study.

References

1. Acharya AP, Panda SK, Prusty BK. Diagnosis and confirmation of Theileria annulata infection in cattle in Odisha, India. J Entomol Zool Stud. 2017;5(4):15431546.
2. Ananda KJ, D'Souza PE, Puttalakshmamma GC. Prevalence of haemoprotozoan diseases in crossbred cattle in Bangalore north. Vet World. 2009;2(1):15.
3. Benjamin MM. Outline of veterinary clinical pathology. 1st ed. New Delhi: Kalyani Publishers; 1998. p. 25-37.
4. Dharanesha NK, Giridhar P, Byregowda SM, Venkatesh MD, Ananda KJ. Seasonal prevalence of blood parasitic diseases in crossbred cattle of Mysore and surrounding districts of Karnataka. J Parasit Dis. 2017;41(3):773-777.
5. Farooq U, Tufani NA, Malik HU, Mir MS. Clinical and morpho-molecular epidemiology of bovine theileriosis in Kashmir, India. Indian J Anim Res. 2019;53(3):375381.
6. Ganguly A, Bisla RS, Singh H, Bhanot V, Kumar A, Kumari S, et al. Prevalence and haematobiochemical changes of tick-borne haemoparasitic diseases in crossbred cattle of Haryana, India. Indian J Anim Sci. 2017;87(5):552-557.
7. Ghosh S, Patra G, Borthakur SK, Behera P, Tolenkhomba TC, Deka A, et al. Prevalence of haemoprotozoa in cattle of Mizoram, India. Biol Rhythm Res. 2020;51(1):76-87.
8. Kaur R, Yadav A, Rafiqi SI, Godara R, Sudan V, Chakraborty D, et al. Epidemiology, haematology and molecular characterization of haemoprotozoon and rickettsial infections in cattle of Jammu region, North India. BMC Vet Res. 2021;17(1):219.
9. Krishna Murthy CM, Ananda KJ, Adeppa J. Prevalence of haemoprotozoan infections in bovines of Shimoga region of Karnataka. J Parasit Dis. 2016;40(3):890-892.
10. Kumar B, Maharana BR, Prasad A, Joseph JP, Patel B, Patel JS. Seasonal incidence of parasitic diseases in bovines of south-western Gujarat (Junagadh), India. J Parasit Dis. 2016;40(4):1342-1346.
11. Maharana BR, Kumar B, Prasad A, Patbandha TK, Sudhakar NR, Joseph JP, et al. Prevalence and risk factors of haemoprotozoan infections in cattle and buffaloes of south-west Gujarat, India. Indian J Anim Res. 2016;50(5):733-739.
12. Mankani PG, Veena M, Puttalakshmamma GC, Shivakumar V, Satheesha SP, Inamdar B. Occurrence of haemoprotozoan diseases in cattle in Hassan, Karnataka. Int J Livest Res. 2024;14(5):31-34.
13. Sharma D, Vatsya S, Harit A, Kumar RR, Kumar S. Prevalence of theileriosis in large ruminants of Uttarakhand. Pharm Innov J. 2021;10(7):922-925.
14. Singh NK, Singh H, Jyoti, Haque M, Rath SS. Prevalence of parasitic infections in cattle of Ludhiana district, Punjab. J Parasit Dis. 2012;36(2):256-259.
15. Subapriya S, Senthil NR, Gowri B, Chandrasekaran D, Gopalakrishnan A, Arunaman CS, et al. Prevalence of haemoprotozoal diseases in cattle: a review of 6000 cases. Pharm Innov J. 2021;10(8):535-541.