The present study was conducted to record the prevalence of gastrointestinal (G.I.) parasitism in pigs in three districts of Tripura. The study was conducted for eight months starting from March to October. The study involved a total number of 388 randomly selected pigs of different age groups.
3.1. Overall Prevalence of G.I. parasitism in pigs:
The present study revealed that pigs of Tripura were very much susceptible to GI parasite infection. Out of 388 pigs, 239 (61.59%) were found positive with one or more species of GI parasites. During the study period, pigs were found infected with mainly 6 types of parasites. Among the identified parasites, there were four (4) species of nematodes such as Ascaris sp., Metastrongylus sp., Strongyloides sp., Trichuris sp. and two species of protozoa such as Coccidia sp and Balantidium coli. In the present study, highest prevalence was observed for Ascaris sp. (32.67%) Most importantly, out of 388 pigs, 46.91% were found to be infected with more than one species of GI parasites (Table 1).
Table 1
Prevalence of gastrointestinal parasite in pigs of Tripura according to farming system, districts, age and parasitic species
Variables | Number of pigs screened | Number of pigs infected | Prevalence (%) | p value |
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Farming system |
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Free range | 108 | 75 | 69.44 | 0.073 |
Semi-intensive | 168 | 103 | 61.31 |
Intensive | 112 | 61 | 54.46 |
District |
Sepahijala | 124 | 73 | 58.87 | 0.548 |
Khowai | 175 | 113 | 64.57 |
West Tripura | 89 | 53 | 59.55 |
Age |
Piglet (below 6 months) | 110 | 65 | 59.09 | 0.002* |
Grower (6–12 months) | 158 | 113 | 71.52 |
Adult (Above 12 months of age) | 120 | 61 | 50.83 |
Parasitic species |
Ascaris sp. | 388 | 126 | 32.47 | 0.000* |
Metastrongylus sp. | 388 | 68 | 17.53 |
Strongyloids spp. | 388 | 75 | 19.33 |
Trichuris spp. | 388 | 62 | 15.98 |
Coccidia sp. | 388 | 48 | 12.37 |
Balantidium coli | 388 | 42 | 10.82 |
Mixed infection | 388 | 182 | 46.91 |
*Denotes statistically significant p value (p < 0.05), Chi square statistics |
The GI parasitism constitutes a major impediment to efficient and profitable livestock production (Boes et al. 2000; Joachim et al. 2001). GI parasitism in swine affects performance in terms of efficient feed conversion, poor growth rate, reduced weight gain and the condemnation of affected organs after slaughter (Nsoso et al. 2000). The prevalence of GI parasitism in pigs have also been reported from different parts of India and abroad (Nsoso et al. 2000; Rajkhowa et al. 2003; Deka et al. 2005; Dutta et al. 2005; Eijck and Borgsteede 2005; Tamboura et al. 2006; Tiwari et al. 2009, Dey et al. 2014; Laha et al. 2014; Kaur et al. 2017). The present finding varied from the previous reports probably because of geographical and climatic conditions, variation in pig breeds, variation in farm management practices, the nutritional and health status of the pigs, consciousness of farmers about the use of anthelmintics or antiparasitic agents, method of sample collection and analysis, and differences in the number of samples analyzed. The overall higher prevalence of Ascaris sp. observed in this study was also reported in other studies by Tamboura et al. (2006) in Burkina Faso, Dey et al. (2014) in Bangladesh, Nsoso et al. (2000) in Botswana and Laha et al. (2014) in NE India. However, difference is prevalence percentage across the studies may be due to seasonal and geographic variations that favor the proliferation of the helminthes. Perpetual wet unhygienic farm conditions with favourable environmental temperatures can lead to high infection rates with A. suum (Kagira 2010; Obonyo et al. 2012) Moreover, the female is capable of laying more than 200,000 eggs per day (Soulsby 1982). The eggs have thick, tough shells that protect the developing larvae. These eggs can withstand adverse weather conditions and some chemicals, and they may remain viable and infective for extended periods (Roepstorff and Nansen 1998).
Among protozoan parasites, the Coccidia sp. (12.37%) was the most identified parasite which is in agreement with Tiwari et al. (2009), Dey et al. (2014) and Eijck and Borgsteede (2005). Poor management and unsanitary conditions in the pig farms on most of the farms surveyed could have accounted for the high rate of Coccidia infection (Nwafor et al. 2019).
3.2. Sex wise prevalence of gastrointestinal parasites
The present study included 168 male and 220 female pigs of different age groups. The sex wise prevalence of the G.I. parasites in pigs is presented in Table 2. The overall prevalence of G.I. parasites was found significantly (p < 0.05) higher in females (67.27%) than male (54.17%) pigs in this study. The highest prevalence recorded for Ascaris sp., in both the male and female animals. The prevalence of mixed infection was also found to be higher in female than in male pigs.
Table 2
Prevalence of gastrointestinal parasites in pig of Tripura according to various epidemiological factors
Epidemiological factor | Number of pigs screened | Number of pigs infected | Prevalence (%) | Relative risk | Odd Ratio | 95% CI | p value |
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Sex |
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Male | 168 | 91 | 54.17 | 0.81 | 0.57 | 0.38–0.87 | 0.011* |
Female | 220 | 148 | 67.27 |
Breed |
Non-descript | 175 | 115 | 65.71 | 1.13 | 1.38 | 0.91–2.08 | 0.142 |
Cross breed | 213 | 124 | 58.22 |
Season |
Summer | 201 | 116 | 57.71 | 0.88 | 0.71 | 0.47–1.07 | 0.117 |
Monsoon | 187 | 123 | 65.78 |
CI- Confidence Interval |
*Denotes statistically significant p value (p < 0.05), Fishers’ exact test |
The higher prevalence of GI parasites in female population is in agreement with the earlier study of Tamboura et al. (2006), Obonyo et al. (2012) and Dey et al. (2014). However, higher prevalence of GI parasites in male was recorded by Sowemimo et al. (2012) and no significant different between sexes was reported by Nsoso et al. (2000) in Botswana. The reason of higher prevalence of infection in the females cannot be explained exactly but factors such as hormonal imbalance, gravidity, parturition, lactation and stress might have lead to suppression of immunity leading to predisposition to pathogens. Moreover, higher level of lactation and progesterone hormones also make the female individual more susceptible to any infection (Swai et al. 2010).
3.3. Age wise prevalence of G.I. parasites in pigs
The prevalence of G.I. parasites in different age groups of pigs is presented in Table 1. In the present study, significant difference (p < 0.05) was observed in terms of GI parasitic infection among the three age groups of pigs. it was found that prevalence of GI parasites in pig were higher in grower pigs (71.52%) followed by piglets (59.09%). However, all the 6 types of GI parasites were detected in all three age groups of pigs. The prevalence of mixed infection was also found to be higher in grower pigs and piglets in comparison to the adults. The highest prevalence was observed for Ascaris sp. in all three age groups.
This uneven age-specific herd prevalence of pig GI parasite is a common phenomenon that may be due to different host-parasite interactions, especially immunity to the parasite (Roepstorff and Nansen 1994; Damriyasa and Bauer 2006). The significantly (P < 0.01) higher GI parasite infection in grower and piglets found in this study is in agreement with Chou et al. (2008), Dey et al. (2014) and Sharma et al. (2020). Higher infection in the growers is attributed to their more exposure to the infective stages of parasite while grazing just after weaning. Whereas, the higher prevalence in piglets is might be associated with under developed immune status, poor nutrition and lack of exposure to the GI parasites. On the contrary, the less prevalence observed in the adult pigs is might be due to the resistance against re-infections (Sharma et al. 2020).
3.4. Breed wise prevalance of gastrointestinal parasites of pigs
In the present study, 175 non-descript breed and 213 cross breed pigs of different age groups were examined. The breed wise prevalence of the G.I. parasites in pigs is presented in Table 1. The overall prevalence of G.I. parasites was found slightly lower in cross breed (58.22%) than non-descript (65.71%) pigs, in this study. The highest prevalence was recorded for Ascaris sp. in both the groups. Moreover, the prevalence of mixed infection was also found to be higher in non-descript breed than in cross breed pigs.
In the present study, the higher prevalence of GI parasitic infections was observed in non-descript is in agreement with the findings of Muraleedharan et al. (1994) in Mysore and Mandya districts of Karnataka and Krishna Murthy et al. (2016) in Shimoga region, Karnataka. The high rate of GI parasite infection observed in non-descript pig breeds in the present study might be due to unhygienic farming practices in the unorganized farms with limited use of anthelmintic (Singh and Rath 2013). Whereas, the cross-breed pigs are mostly reared in organized farms and given utmost care with better animal husbandry practices. Furthermore, the non-descript breeds are reared completely in extensive system and are allowed to graze near water land, forest and bushes which increases the chance of picking up infection (Kabir et al. 2011).
3.5. Farming System wise Prevalance:
In the present study, 108 animals were reared in free range rearing farming system, 168 animals were in semi-intensive rearing system and 112 numbers of pigs were kept in intensive system. The farming system wise prevalence of the G.I. parasites in pigs is presented in Table 1. The prevalence of G.I. parasites were found higher in pigs kept in free range system (69.44%) of farming followed by semi intensive (61.31%) rearing system and lowest in intensive (54.46%) type of farming. The prevalence of mixed infection was also highest in free range farming system. However, Ascaris sp. was found to be the most prevalent parasitic species in all three farming systems.
The farming system plays a remarkable role in spreading GI parasite infection. Worm load and variety of helminthes species mostly depends on the type of swine production system. In the highly intensive production systems, the infection levels are usually low and involve only few species. This is because intensive pig farms have better management and treatment standards (Lin et al. 2013). On the other hand, in most traditional extensive outdoor management systems, the poor hygienic conditions allow a higher prevalence, burden and rate of helminth transmission without anthelmintic interventions (Roepstorff and Nansen 1994; Nansen and Roepstorff 1999). Infections are thus likely to be more severe in scavenging pigs, compared to those in intensive system of production. In present study, the majority of pigs are reared in traditional free ranging outdoors system. This might be the reason behind the observed higher prevalence of GI parasites. Rearing pigs in free range system and their free access to potentially contaminated areas is a vital risk for persistence of parasitic infection (Chawhan et al. 2014; Kaur et al. 2017).
3.6. Area wise prevalence of gastrointestinal parasites of pigs
The prevalence of G.I. parasites in pigs in different districts of Tripura is presented in Table 1. Among the three districts of Tripura, highest prevalence of GI parasites in pigs was observed in Khowai district (64.57%) followed by West Tripura (59.55%) and Sepahijala (58.78%). In all three districts, the highest prevalence was observed for Ascaris sp. Notably, no trematode eggs were detected in fecal samples collected from all three districts in this study. The high frequency of nematode parasite infections in the pigs is an indication of both a favourable environment for the survival and development of pre-infective stages of nematodes and the limited veterinary care of these animals in this region.
3.7. Season wise prevalence of gastrointestinal parasites of pigs
Season wise prevalence of G.I. parasites in pigs based on feacal sample examination is presented in Table 2. The present study was conducted over a period of eight months from March to October. The highest prevalence of GI parasites was observed in the month of July (68.75%) and that of lowest in the month of April (52%). However, the prevalence of mixed infection was found to be highest in the month of September (57.5%) and lowest in the month of October (40.74%) (Data not shown). The highest prevalence was observed for Ascaris sp. in all 8 months under this study. Altogether, it was found that the overall prevalence of G.I. parasite in monsoon season was higher (65.78%) than the summer (57.71%). Further, the prevalence of all four nematodes was also found to be higher in the monsoon season than in the summer.
The highest prevalence recorded in the month July which is in agreement with the findings of Das et al. (2020) in Meghalaya. This might be on account of warm and wet climate which is most congenial for the majority of nematode parasites (Rogers 1962). The moist weather in the rainy season favours the development of the pre-parasitic stages of the nematodes (Yadav and Tandon 1989). The high rainfall in the study area coupled with the very short dry season results in the persistent high humidity in the environment which satisfies the optimum requirements needed for the development of nematode eggs and, also ensures a prolonged survival of eggs and larvae in the soil, increases the possibility of host infection. Further, to some extent the feeding habit of pigs is also one of the factors for such a high infection rate of nematodes, Ascaris sp. The seasonal pattern of overall nematode infections observed in the investigation is attributable to one factor, the presence of both eggs and larvae in the soil throughout the year.