Epidemiology and molecular characterization of Theileria annulata in cattle from central Khyber Pakhtunkhwa, Pakistan

Abstract

Theileria annulata is a tick-borne hemoprotozoan parasite responsible for tropical theileriosis in the bovine population, which causes substantial economic losses to the livestock sector. The present study has investigated, characterized, and shaped epidemiologic and phylogenetic profiles of T. annulata infection in the cattle population of central Khyber Pakhtunkhwa, Pakistan. A total of 600 blood samples were collected from cattle. Microscopy and PCR (18S rRNA taxonomic marker) assays were performed to detect T. annulata infection in cattle from the study area. The overall relative prevalence rates of T. annulata in the examined cattle population were 12.8% (microscopy) and 23.7% (PCR). District-wise analysis (microscopy/PCR) showed that cattle from district Mardan were found more infected (16.0%/28.0%), as compared to cattle from district Charsadda (13.5%/25.5%) and district Peshawar (9.0%/17.5%). Based on host demographic and ecological parameters analysis, theileriosis was found to be higher in young, female, crossbred, freely grazing, tick-infested, and irregular/no acaricides treated cattle. The univariate logistic analysis showed that host age, tick infestation, acaricides use, and feeding method were significant risk factors (P<0.05) whereas multivariate analysis indicated that host age, gender, tick infestation, acaricidal application, and feeding method were potential risk factors (P<0.05) for tropical theileriosis in the cattle population. Phylogenetic and sequence analysis showed that T. annulata 18S rRNA isolates shared homology and phylogeny with other isolates from Asia and Europe. This study has addressed the epidemiology and phylogeny of T. annulata circulating in bovid in the study area where gaps were still present. These findings will serve as a baseline and will facilitate future large-scale epidemiological investigations on tropical theileriosis in the cattle population at a national level.

Molecular Epidemiology of Theileria annulata in Cattle from Two Districts in Punjab (Pakistan)

“…In the present study, a higher prevalence of T. annulata was recorded in female cattle from Lodhran than in males from the same District (Table 3). Our results are in accordance with the findings of Inci et al [46], Khattak et al [22] and Saeed et al [13], as they all reported a higher prevalence of T. annulata in female cattle. Saeed et al [13] reported that comparatively weak immune response and more hormonal fluctuations in females increases the incidence of theileriosis.…”

“…During the present study, we found that 33% of cattle from Dera Ghazi Khan and 24% from Lodhran District were infected with T. annulata ( Table 1 ). Among TBDs, bovine theileriosis has been frequently reported from various parts of Pakistan, and in previously documented studies, the prevalence of T. annulata in cattle was reported to be 33% in Peshawar and Kohat [ 19 ], 30% in Dir Upper and Chitral [ 20 ], 28% in Laki Marwat [ 21 ], 23.7% in Charsadda, Mardan and Peshawar Districts in Khyber Pakhtunkhwa [ 22 ], 21% in Layyah [ 23 ], 19% in various districts in Punjab [ 24 ] and 18.8% in three distinct zones of Khyber Pakhtunkhwa Province [ 25 ]. Similarly, the prevalence of T. annulata in cattle has been reported in other tropical and subtropical countries as well.…”

Occurrence of ticks and tick-borne mixed parasitic microbiota in cross-bred cattle in District Lahore, Pakistan

“…It has also been reported in a study that infection of B. bigemina is higher among the age groups of 2-7 years in cross-bred animals (Velusamy et al, 2014). In a study carried out in Khyber-Pakhtunkhwa, Pakistan, Ullah et al (2021) reported that 23.7% of cattle were found infected with T. annulata, however, theileriosis was found to be higher in young animals as compared to adults cross-bred cattle. Another research from Pakistan reported over all T. annulata prevalence of 21%, with cross-bred cattle most susceptible (28%) followed by Sahiwal breed (19%) (Parveen et al, 2021).…”

An insight into misidentification of the small-subunit ribosomal RNA (18S rRNA) gene sequences of Theileria spp. as Theileria annulata

“…[ 2 ]. The mild and subclinical infections are overlooked and animals remain carriers, but during stress conditions, the disease may flare up to a clinical state [ 6 , 7 ]. The variable clinical presentation as well as irregular clinical signs and symptoms of the disease frequently noticed by the field veterinarians could be related to genetic changes in this protistan parasite [ 8 ], but this needs to be further investigated.…”

“…The commonly used genetic markers for T . annulata identification and characterization are the small-subunit ribosomal RNA (18S rRNA) gene [ 7 , 14 , 15 ], the T . annulata merozoites surface antigen (Tams1 ) encoding gene [ 16 , 17 ], the β-tubulin gene [ 18 ], cytochrome b gene [ 19 , 20 ] and the heat shock protein 70 encoding gene (HSP70) [ 21 ].…”