In the present study, three screening methods were adopted to record the prevalence of paramphistomosis infection in domestic ruminants. An overall prevalence of 24.29%, 32.51% and 42.0% of infection was observed by DS, SD and SH examinations, respectively. Statistically, a significant difference was noticed (Table 2).
The prevalence of infection in cattle by DS and SD methods were 17.43% and 31.19%, respectively (Table 2). In contrast, earlier studies reported a high prevalence of paramphistomosis infection in cattle
(Paul et al., 2011; Saha et al., 2013). Numerous studies reported a lower prevalence rate of infection in cattle from India. From Andhra Pradesh, 5.94% of infection was reported (
Kumari and Hafeez, 2005) and similar reports were recorded from Punjab
(Singh et al., 2012), Maharashtra
(Gadre et al., 2008), Rajasthan (
Choubisa and Jaroli, 2013), Telangana state (
Murthy and Rao, 2014) and Uttarakhand
(Maitra et al., 2014). In a study, none of the cattle were found positive for paramphistomosis in the Nilgiri district of Tamil Nadu, probably this may be due to insufficient number of samples (n=20)
(Allwin et al., 2016).
In the current study, 26.09%, 33.18% and 42.15% of prevalence of paramphistomosis in sheep was noticed by DS, SD and SH examinations, respectively (Table 2). Differing with the present findings, lower prevalence of ovine paramphistomosis was reported from various parts of India (
Shabih and Juyal, 2005;
Choubisa and Jaroli, 2013;
Balakrishnan et al., 2014; Tramboo et al., 2015). This may be due to the free grazing habit of sheep leads to heavy infection by ingesting the metacercaria than cattle and goats (
Swarnakar and Kumawat, 2013). In the present study, the infection rate in goats was between 20.66 - 40.85% by all three detection methods (Table 2). In comparison, a higher prevalence of infection was noted by
Uddin et al., (2006). In north India, a low prevalence of infection in goats was observed by earlier workers (
Shabih and Juyal, 2005;
Choubisa and Jaroli, 2013;
Godara et al., 2014; Maitra et al., 2014). The fluctuations in prevalence of infection among the domestic animals could arise as a result of drinking from drying water bodies where the levels of metacercariae tend to increase
(Rolfe et al., 1991).
Slaughterhouse survey is a complex way of gathering information on epidemiology of parasite infections in livestock. Based on abattoir study, the prevalence of paramphistomosis in cattle, sheep and goats showed not much variation (40.85 to 43.12%) (Table 2). For this, one of the reasons may be the common grazing areas and most of the infections in sheep and goats are due to transmission through bovines (
Dunn, 1969). The present study reported a prevalence of infection in cattle at 43.12%. Previous reports published a higher prevalence ranging from 50.0 to 90.6% of infections in cattle
(Bunza et al., 2008; Azam et al., 2011). From India,
Swarnakar et al. (2014) reported, the highest prevalence of infection in cattle slaughtered in Rajasthan. The higher infection in cattle may be due to large stomach, thus provides a wide surface area for fluke attachment (
Barger 1993), improper deworming and regular recovery of flukes in slaughtered animals. Further, a higher prevalence in buffaloes may be due to the wallowing habit in contaminated water
(Cheema et al., 1997). Few studies from India reported a low prevalence of infection in cattle (
Kumari and Hafeez, 2005;
Chaudhary et al., 2014). Sheep carcasses were examined for finding the adult flukes by others in India and their findings were lower when compared to the present observations
(Shahnawaz et al., 2011; Chaudhary et al., 2014; Godara et al., 2014). The lower prevalence might be due to the sheep which were switched over to stall feeding (
Shabih and Juyal, 2005;
Singh et al., 2012). Further, in the present study area, usually the large ruminants were confined to restricted grazing areas or mostly stall-fed, whereas small ruminants were of migratory behavior which made them susceptible to infection. Further, in this study visits to slaughterhouses were performed on weekdays, but more animals were brought on Sunday to cope up the demand. This may be one of the factors for higher infections as they form the bulk of animals brought to abattoir for slaughter, thus higher probability of being found positive for infection. Another reason is hot and dry season prevailed during the sampled period, which concentrated the snail population in water bodies leading to aggregation of snail hosts enhancing the chances of heavy infection
(Shahnawaz et al., 2011; Singla et al., 2017). Caprine paramphistomosis detected in the current study was found to be higher than other studies
(Chaudhary et al., 2014; Godara et al., 2014). This may be explained by variation in genetic constitution, agro-ecological conditions, breed of animals and exposure to the source of infection
(Uddin et al., 2006).
In cattle, age-wise prevalence of paramphistomosis showed a higher prevalence of infection in the age group of 2-4 years (Table 3). The present findings were in agreement with earlier observations (
Kumari and Hafeez, 2005;
Paul et al., 2011; Swarnakar et al., 2014). In contrast,
Khan et al., (2008) reported a higher prevalence of infection in young cattle. The low infections of biliary amphistomosis in adult cattle may be due to the mechanical barriers by fibrosis in bile ducts which may reduce the chances of establishment of the fluke
(Alim et al., 2005). Prevalence in aged animals could be explained by the accumulation and longevity of infection would allow them to remain for a longer period, immunological phenomenon, grazing habits, method of study and management practice.
In sheep and goats, age-wise prevalence of paramphistomosis was recorded in the present study. Except, sheep of <1 year age group, all other small ruminants of more than one year age group showed a higher prevalence of paramphistomosis infection (Table 4). As the age advances, the animals were more infected, except the sheep under one year age group which showed a significant higher prevalence rate by SH examination. The present findings were corroborated with
Bunza et al., (2008). Low prevalence of infection in animals of 1-2 years may be due to the fact that, only healthy young animals were brought to slaughter, and those affected by acute paramphistomosis were dead even before they were brought to slaughter and long prepatent periods of fluke infection. In contrast, the higher prevalence of infection in young sheep was noted by
Shahnawaz et al., (2011) and
Godara et al., (2014). The prevalence of infection in goats of more than one year group was reported to be high in the present study by SH examination (63.27%) and this observation was similar to other findings
(Uddin et al., 2006; Bunza et al., 2008).
The prevalence of infection in this study was reported to apparently higher in female sheep than males (Table 5) and is consistent with
Godara et al., (2014). The possible reason for higher infection in females may be due to loss of immunity during pregnancy, birth and lactation (
Barger, 1993). In the present study, male goats showed higher prevalence of infection than females by SH examinations and it was similar to the reports of
Uddin et al., (2006). In a study by
Paul et al., (2011) reported female cattle were more infected by 1.79 times than males.
Swarnakar et al., (2014), reported male buffaloes were more susceptible to the infection than female animals and this may be due to lack of care because of their future economic importance.
In cattle, five fluke species were identified morphologically
viz.,
C. cotylophorum, P. cervi, G. crumenifer, F. elongatus, and
Gigantocotyle species (Fig 2-6). But in small ruminants, only first three were noticed apart from mixed infections. The exact cause of mixed infection is difficult to explain, but might be competition among the parasite for accommodation and food (
Alim et al., 2005). The variation among species may be explained that, cattle have an indiscriminate type of grazing behavior and goats do not usually graze in marshy areas. In addition, goats are browsers by nature and they tend to graze in very rare cases and there is low probability of picking of the infection. The present study supports the findings of
Kumari and Hafeez (2005) and
G. crumenifer was the predominant species in both the studies. Our findings were corroborated with
Swarnakar et al., (2014) who reported
P. cervi and
Gigantocotyle spp. in buffaloes from Rajasthan. It is significant to note that the infection in cattle with
G. crumenifer was more prevalent compared to rest of the amphistome species. The variations can be attributed to the densities of snails in the water bodies (
Swarnakar and Kumawat, 2013). From Maharashtra,
Gadre et al., (2008) found only
Paramphistomum spp. in cattle. Other studies observed various amphistome species in cattle with different combinations of mixed infection with one or more species, in which some were identical to the present study
(Rolfe et al., 1991; Dube et al., 2004). Many studies on the prevalence of infection are based on morphology of amphistome egg, which is not possible to identify the parasite species
(Saha et al., 2013). In future studies, this may be overcome by molecular techniques, even dung sample with amphistome ova is sufficient for species identification.
In the present study,
G. crumenifer is the most predominant species in sheep and goats, followed by
C. cotylophorum and
P. cervi (Table 6) and is in agreement with earlier studies by
Kabir et al., (2010). In India,
Shahnawaz et al., (2011) identified
C. cotylophorum,
G. crumenifer and
Carmyerius spatiosus in sheep of Kashmir valley. In goats, the present observations were in agreement with other reports of
Uddin et al., (2006) and
Kabir et al., (2010).
