Introduction

Parasitic diseases are thought to be the primary restraint to the economy of farmers by reducing the growth and production of cattle. Sarcocystosis caused by Sarcocystis spp., a tissue coccidian parasite involves carnivores and humans as definitive hosts and domestic animals as intermediate hosts. Cattle become infected with the parasite by ingestion of sporocysts or sporulated oocysts of Sarcocystis through contaminated food or water and show symptoms of reduced weight gain, poor feeding efficiency, muscle weakness, reduced milk yield, abortion, condemnation of meat due to macroscopic sarcocysts and mortality depending on the immune status of the host and dose of ingested sporocysts (Dubey et al. 1989). Cattle are mainly infected with Sarocystis cruzi, S. hirsuta and S. hominis. Out of these three species, S. hominis is zoonotic and infect humans by consumption of undercooked beef containing the larval stage sarcocyst resulting in digestive upset (Fayer 2004). It was reported about 50% of parasitic cysts found in muscles of cattle belong to S. hominis (WHO 1981). Sarcocystosis is routinely diagnosed by pathological (gross examination, impression smears, histopathology and digestion methods) and serological methods (IFAT and ELISA) that identify genus level of Sarcocystis spp. Prevalence of disease has been reported from different parts of world including India (More et al. 2008; Hamidinejat et al. 2010; Dafedar et al. 2011; Chiesa et al. 2013). However the reports on prevalence of sarcocystosis in cattle in Andhra Pradesh are scanty (Venu and Hafeez 2000). Hence owing the zoonotic significance of sarcocystosis and the importance of epidemiology of disease to follow an appropriate control strategy, the present study was carried out to know the prevalence of sarcocystosis in cattle in Chittoor district of Andhra Pradesh.

Materials and methods

A total of 150 slaughtered cattle that were slaughtered at Tirupati, Chandragiri, Chittor, Renigunta and Pakala regions in Chittor district, Andhra Pradesh were examined macroscopically and microscopically for a period of 1 year to study the prevalence of sarcocystosis. Age and sex of cattle were taken into account. Different organs of cattle including predilection sites viz., oesophagus, diaphragm and heart were examined thoroughly for the presence of macroscopic sarcocysts. Further tissues samples of each slaughtered cattle from different predilection sites were collected and subjected to Pepsin–HCl tissue digestion technique for microscopic examination. Twenty grams of tissue samples (pooled tissues from different predilection sites) collected from each cattle carcass, irrespective of visible macroscopic cysts were incubated in 50 ml of acid pepsin solution for 20 min at room temperature (2.6 g pepsin, 5 g Nacl, 7 ml 1 M Hcl, 993 ml distilled water). The suspension was then filtered using a 53 µm pore sieve, and centrifuged at 5000 rpm for 3 min. Finally, the sediment was suspended in 0.5 ml distilled water and a drop of the solution was examined for the presence of bradyzoites under a light microscope. The representative tissue pieces were also fixed in 10% neutral buffered formalin and processed routinely for histopathological evaluation. Data obtained was classified according to age and sex and was analyzed as per standard statistical techniques (Petrie and Watson 2013). Chi-square test of association was used to establish association between the infection status and variables such as age and sex of the cattle.

Results and discussion

Macroscopic sarcocysts were observed only in nine out of 150 cattle screened and were observed in oesophagus but not in other predilection sites viz., skeletal muscles, cardiac and diaphragmatic muscles. Grossly, sarcocysts were elongated, milky-white in colour and were embedded in the muscular tissue (Fig. 1). Examination of tissue samples collected from different predilection sites from each of 150 slaughtered cattle by pepsin–HCl digestion revealed presence of live banana shaped bradyzoites (Fig. 2) in 134 cattle under light microscopy. In general, three cattle were exclusively positive for macroscopic cyst, 128 were positive for microscopic sarcocysts and six cattle were positive for both microscopic and macroscopic sarcocysts. The overall prevalence of Sarcocystis infection in slaughtered cattle of Chittoor district, based on macroscopic and microscopic sarcocysts was 91.33% (Table 1). The infection was highly prevalent in Tirupati (97.14%) compared to that of other regions of Chittoor district. It was observed that there was an increase in prevalence over the past 15 years in Tirupati region wherein the prevalence was 71.50% in 1996 (Venu and Hafeez 2000). The increased prevalence rate might be due to the increased source of sporocysts in pasture to cattle from definitive hosts. Similarly very high rate of prevalence between 91.0 and 100% was also reported across the globe viz., United States (Fayer and Dubey 1986), Iraq (Latif et al. 1999), South-West of Iran (More et al. 2008), Argentina (Hamidinejat et al. 2010), Southern Italy (Bucca et al. 2011), Karnataka, India (Dafedar et al. 2011), Italy (Chiesa et al. 2013) and Yazd and Hungary (Hornok et al. 2015). In contrast to the present findings, low prevalence of Sarcocystis spp. has been reported from Egypt (Badawy et al. 2012) and Malaysia (Latif et al. 2013). The diversity in rate of prevalence could be due to the several factors such as system of breeding, climatic factors, age of sampled animals and type and anatomical site of diagnosis (Dubey et al. 1989) in addition to different regions and availability of definitive hosts.

Fig. 1
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Cattle oesophagus: note macroscopic sarcocysts

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Fig. 2
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Giemsa stained Bradyzoites ×1000

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Table 1 Prevalence of Sarcocystis infection in cattle in different regions of Chittoor district
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Macroscopic sarcocysts in meat are probably a serious meat sanitation problem and economic problem due to condemnation of infected carcass. The prevalence of macroscopic sarcocysts in the present study was low (6.57%), compared with that of microscopic sarcocysts (93.43%) which could be due the connection between cattle and faecal sample of feline definitive hosts in pasture is less than canine definitive hosts in the area under study as macroscopic sarcocysts are of cat source. Additionally, development of macrocysts of Sarcocystis spp. takes for several years and cattle are slaughtered prior to the maturation of cysts as is also opined by Nourani et al. (2010). Similarly Latif et al. (1999), Hamidinejat et al. (2010) and Nahed et al. (2014) also reported the low prevalence of macroscopic sarcocysts in cattle in Iran and Egypt, respectively. Macroscopic sarcocysts were exclusively found in the oesophagus that was in accordance with the findings of Domenis et al. (2011) and Xiang et al. (2011).

The results of age-wise and sex-wise prevalence were summarized in Table 2. There was a significant relationship between the prevalence of infection among different age groups (P < 0.001). The prevalence was found to increase with advancement of age with high infection rate of 95.65% among the old animals which was consistent with data of Sarcocystis infection in cattle from other countries (Hornok et al. 2015) and in other live stock species (Abu-Elwafa et al. 2015). This could be due to prolonged exposure of aged animals to the sporocysts infection. In contrast, Bucca et al. (2011) and Hajimohammadi et al. (2014) observed no significant association between Sarcocystis infection and age of cattle. The present study revealed that the prevalence of Sarcocystis infection of both male and females increased with advance in age and there was no significant relationship (P > 0.001) between the rates of infection in female and male cattle within each age group, in accordance with the previous studies (Jehle et al. 2009; Hajimohammadi et al. 2014). In contrast significant association between rate of Sarcocystis infection and sex of cattle was reported by More et al. (2008) and Nourani et al. (2010). Microscopically sections of tissues from each cattle that were positive by tissue digestion technique revealed thick walled cysts (Fig. 3) in six samples (4.5 ± 0.5 µm) and thin walled cysts (Fig. 4) in 131 cattle (0.5 ± 0.12 µm). Further studies on molecular differentiation of Sarcocystis species is necessary as conventional techniques revealed diagnostic limitation in distinguishing the S. hominis from S. hirsuta thick walled cysts (Nourani et al. 2010).

Table 2 Age-wise and sex-wise prevalence of Sarcocystis infection in cattle
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Fig. 3
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Cattle diaphragm muscle: note section showing thick walled sarcocyst H&E ×100

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Fig. 4
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Cattle cardiac muscle: note section showing thin walled sarcocyst H&E ×100

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