Prevalence of gastrointestinal helminth parasite infections in country chicken from Visakhapatnam district Andhra Pradesh India

Abstract


Introduction
Poultry products form one of the most important sources of protein for mankind, thus it is important to safeguard the health status of poultry with better management strategies and disease control programmes.Biological invasions are one of the major threats to biological diversity in ecosystems, and parasites might play a role in determining invasion outcomes (Prenter et al., 2004).Though the prevalence of most parasitic diseases seems to have reduced significantly in commercial indoor poultry production systems due to improved housing, hygiene and management, parasitic diseases continue to be of great threat in deep-litter and free-range commercial systems (Permin et al., 1998).The latter consists of country chicken or indigenous domestic fowls (Gallus gallus domesticus) variously referred to as local or rural chicken, backyard poultry or village chicken, desi chicken, or free-range chicken.In villages, rural farmers mostly rear chicken in a freerange management system or scavenging system.Due to this scavenging habit, country chicken are more prone to all types of infections, particularly GIH parasitic infections compared to birds reared on intensive farming.GIH parasitic infestations are often neglected despite their patho-physiological effects like malnutrition, anorexia, decreased feed conversion ratio, retarded growth, reduced weight gain, decreased egg production, catarrh diarrhoea, intestinal obstruction, morbidity (Dube et al., 2010), infertility and acute worm infestations that sometimes lead to mortality (Katoch et al., 2012).Moreover, these infections are generally influenced by factors such as temperature and humidity, which alter the parasites' population dynamics resulting in dramatic changes in their prevalence and intensity (Magwisha et al. 2002).

Study area
The study was carried out in Visakhapatnam district situated between 81°06′ and 83°31'E, of the Eastern longitudes and 17°15′ and 18°32'N, of the Northern latitudes (Fig. 1).The boundaries of this district are Vizianagaram in the North-West direction, the East Godavari in the South-West and the Bay of Bengal in the South.The length of the coastline is 135 km.The annual temperatures range between 20°C to 38°C.

Sampling
Guts of three hundred (300) country chicken (Gallus gallus domesticus) were investigated in an annual cycle from January 2021 to December 2021, by taking 25 samples per month.Freshly slaughtered intact GIT samples of chicken were collected from chicken markets covering different locations in Visakhapatnam district.Before slaughtering the chicken, host details like sex, temperature and weight were recorded at the site itself.Collected gut samples were immediately stored in an ice box and brought to the Department laboratory for further analysis (Fig. 2).

Parasitological examination
The GIT of each host was slit opened by a longitudinal incision along the duodenum to rectum including caecal tubes and immediately the pH of the GIT was recorded.A macroscopic examination of the different regions of GIT was carried out to collect and separate the visible parasites in petri dishes according to predilection sites for relaxation (Fig. 3).
Undetectable parasites were examined through a stereo microscope.Adults and undamaged cestodes and trematodes were fixed in AFA solution, whereas nematodes were fixed in 70% glycerine alcohol and preserved as permanent mounts (Soulsby 1982;Cable 1957: Belghyti 1994).Parasites were identified based on helminthological keys described by Yamaguti (1959Yamaguti ( , 1961)), Khalil et al. (1994) and Anderson (2000) under a light microscope.

Statistical analysis
Data collected during the present study were tabulated and analysed to show the population and parasite -prevalence, mean intensity, mean abundance and dominance index of GIH infection in country chicken (Bush et al. 1997).Statistical analysis was performed using one-way ANOVA to understand the significant differences in infection between different GIH parasites and seasons (p > 0.05).The data was analysed using MS Excel 2019 of MSO version 2210 and IBM SPSS Statistics 26.

Overall Prevalence
Out of 300 country chicken screened, 261 were found infected with helminth parasites with an overall prevalence of 87.00%.Cestodes and nematodes were more prevalent than trematodes.The highest infection was recorded with cestodes (83.00%) followed by nematodes (70.00%) while the lowest percentage of infection was found with trematodes (0.67%) (Table 2).

Monthly Prevalence of Infection
Though infection was noted throughout the study period, it varied during different months.Overall infection was maximum in the month of July at 100.00% (182.84) and lowest in December at 72.00% (119.50).Among individual groups, the highest cestode infection was found in March (92.00%) and the lowest in September and December with 72.00% in each month.Whereas nematode infection was highest in July (96.00%) and lowest in December (48.00%).
Only two host samples were infected with trematode parasites, in April and October with a prevalence of 4% each (Table 2, Fig. 4).

Monthly Prevalence of Infection
The data on monthly prevalence of individual GIH parasites showed, R. tetragona to be highest in March (76%) and least in November (48%); R. echinobothrida as highest in March (88%) and least in November and December with 60%; R. cesticillus to be highest in May (52%) and least in September, October and December with 28%; D. proglottina to be highest in October (56%) and least in May and July with 32%; A. cuneata recorded highest in October (60%) and least in May (24%); Cotugnia sps.high in March, June and July with 44% and least in October and November with 12%; Hymenolepis sps.were highest in October (52%); A. galli highest in July (68%) and least in October (16%), and H. gallinarum was highest in July (84%) and least in March and December with 40% (Table 4).

Body weight
The body weight of chicken sampled ranged between 0.6 kg and 3.5 kg.To understand the influence of weight on the prevalence and intensity of infection, they were categorized into six groups with a difference of 0.5 kilograms (kg) weight in each group.The highest prevalence of infection was seen in 0.6 -1.0 kg group chicken recording 100% (142.06) and lowest was seen in 3.1-3.5 kg group country chicken recording 80% (107.00).The highest prevalence of cestode and nematode infections was seen in 0.6 -1.0 kg group with 100% (112.41) and 76.47 (38.77) respectively, whereas lowest was seen in 3.1 -3.5 kg group with 80% (65.25) and 60% (55.67) respectively.Trematodes infections were found highest in the group of 1.6 -2.0 kg with 0.96% (31.00) and least in 1.1 -1.5 kg with 0.78% (1.00).The results showed that the prevalence and intensity of infection varied with an increase in the weight of the host (Table 7).

pH
The pH taken from the GI tract of the host samples ranged from 5.0 to 6.0, showing infection of 72/73 at 5.0, 128/131 at 5.5 and 61/96 at 6.0 pH.The overall prevalence was highest at 5.0 with 98. 63% (194.25) and least at 6.0 with 63.54% (78.28).The prevalence and intensity of cestode, nematode and trematode infection were found to be highest at 5.0 with 98.63% (121.69),90.41% (78.67) and 2.74% (16.00) respectively, whereas lowest at 6.0 with 54.17 % (67.17), 45.83% (29.14) and 0.00% respectively.The results indicated an increase in the prevalence and intensity of infection with a decrease in pH levels (Table 7).

Site Specificity of GIH parasites
Most of the GIH parasites recorded during the present study exhibited site selection by restricting their habitat to specific GIT areas in the host.Among the GIH parasites recorded, D. proglottina, A. cuneata, Hymenolepis sps, R. cesticillus were found to be more common in the duodenum, R. tetragona, R. echinobothrida, Cotugnia sps., A. galli were mostly seen in the small intestine, whereas H. gallinarum was found in caecum.
It was also observed that most of the infected intestine walls showed the appearance of nodular formations when heavily infected with R. echinobothrida and A. galli.In the case of A. galli, the lumen of the intestine was thickened with the white velvety mucosal formation and intestinal obstruction due to numerous worms of varying sizes was also noticed (Fig. 8).Further studies on the histopathological architecture of intestine tissues will be carried out in due course of time.

Discussion
In India, though several reports are available on gastrointestinal parasites of country chicken in general, very little data is available on the occurrence of multiple or mixed parasitic infections that show an effect on chicken health severely, thereby causing death and consequent economic loss.Previous studies indicated the common occurrence of GIH infections in most of the free-ranging country chicken from different geographical regions of India.In the present study also heavy prevalence and intensity of GIH parasites were noted in country chicken.The overall prevalence recorded with GIH parasites in free-range poultry birds during the present study was 87.00% (139.29), which is higher than that reported in previous studies 63. 21% (Sreedevi et al. 2014) but less than 100% (Bandi et al., 2020).Most of the reports available from India showed a lesser prevalence of infection in country chicken when compared to the present study viz.71% (Puttalakshmamma et al. 2008) 1).
The country chicken act as hosts to a wide variety of helminth parasites, especially cestode, nematode and trematode parasites.It was noted during the present study that cestode infections are much more common than nematodes.A similar situation was noted in other studies reported by Heyradin et al. (2012) where a prevalence of 83.00% cestode and 58.00% nematode parasites from country chicken and Ashenafi and Eshetu (2004) recorded a prevalence of 86.32 % cestodes and 75.79 % nematodes.No trematode infections were reported in studies carried out elsewhere by Magwisha et al. 2002 andJaiswal et al. 2020.The variations noted in the prevalence of infection during various studies including the present study, could be due to their distribution in different geographical climates which may restrict the parasite transmissions or survival.However, parasites are said to be more dominant in tropical countries where the climate and environmental conditions favour their survival rate.However, the high prevalence of GIH infections recorded in country chicken during the present study could be due to their free-ranging habit which allows them free access to infective stages of parasites through beetles, earthworms, ants etc. which act as intermediate hosts to most of the helminth parasites while in search of feed (Horsfall 1938, Todd and Crowdus 1952, Soulsby 1982).
Studies on the seasonal influence on the prevalence of infections indicated that some parasite species were prevalent during certain seasons and less prevalent during other seasons.In the present study, highest prevalence of GIH parasites was observed during the summer (90%) followed by monsoon (87%) and winter (84%) seasons.Several variations in seasonal prevalence during different investigations in other studies, high helminth infection was reported by Hange et al. (2007), Solanki et al. (2015) and Rehman et al. (2016) during the winter, by Dube et al. (2010) andSreedevi et al. (2016) during monsoon and Naphade and Chaudhari (2013) and Sheikh et al. (2015) during summer seasons.These variations could be due to various environmental conditions which favour the survival of the intermediate host and continues its transmission to other hosts so that the parasite completes the lifecycle.During the present investigation, highest prevalence of 100% with 182.84 parasite intensity was recorded in the month of July by nematodes which coincides with the onset of the monsoon.The onset of monsoon triggers mature nematode parasites to actively release eggs through host droppings into the external environment where they remain viable for a long time and get transmitted to definitive hosts while grazing or through contaminated rainwater (Permin et al. 1998).
The common GIH parasite species recovered in the present study were R. echinobothrida and R. tetragona in cestodes; A. galli and H. gallinarum in nematodes.R. echinobothrida was also reported to be dominant species by Shah et al. (1999).R. tetragona and A. galli were more common, a similar situation was noted by Puttalakshmamma et al. (2008), Javaregowda et al. (2016) and Rao et al. (2018).R. tetragona was reported high in the month of July by Ghosh et al. (2019).H. gallinarum was the most commonly observed nematode by Costa et al. (1986) and Permin (2002).A. galli species had been reported as the common and most important helminth infection of poultry by Sonune (2012), Satish and Priti (2013), Murthy and Rao (2014) and Sahu and Sinha (2016).Nevertheless, several variations were noted regarding the dominance of various individual parasite infections in previous studies carried out by Pickney et al. (2008), Katoch et al. (2012), Butt et al. (2014) and Bandi et al. (2020).
When compared to single infections, mixed infections showed a greater prevalence with different cestode and nematode parasite species.A similar frequency of mixed infections was stated in other cases by Eshetu et al. (2001), Ashenafi and Eshetu (2004) and Hange et al. (2007).On the contrary, single infection was recorded high by Sreedevi et al. (2016) and Naphade and Chaudhari (2013).The variations noted during different studies can be attributed to the food preferences or food availability at a particular time of the year, which to a great extent can influence the establishment of a mixed or single infection.The ability of two or more parasites to survive within the same host may increase the prevalence of mixed infection, but as the number of parasites per host increases, the prevalence decreases due to antagonism with one another within the same host (Reid 1959).
The sex specific prevalence of parasites showed higher prevalence in males than in female country chicken which is similar to those reported in other cases by Radfar et al. (2012), Dar and Tanveer (2013) and Sheikh et al. (2015).This could be because of the fact that females reduce their feeding range during the brooding period and thereby minimising the chances of acquiring infection.Males on the other hand can go far in search of food, increasing the possibility of acquiring parasitic infections.
Studies on the influence of various factors on the prevalence and intensity of infection showed the prevalence and parasite intensity increased with an increase in body temperature whereas both the prevalence and parasite intensity increased with a decrease in pH levels.So far, no literature is available with regard to the influence of body temperature and pH levels on the prevalence of parasitic infections in GIT.Thus, the present study constitutes first attempt to record.
Different GIH parasites inhabit specific sites of the host's GIT called predilection sites, where some parasites live in association with other parasite species.In the present study, D. proglottina, A. cuneata and Hymenolepis sps.were found to restrict their habitat to the duodenum, whereas R. tetragona, R. echinobothrida, Cotugnia sps.and A. galli restricted to small intestines and no parasites were recovered from the trachea, oesophagus, crop and gizzard.A similar situation was reported by Puttalakshmamma et al. (2008) and Katoch et al. (2012) while working on R. tetragona, R. echinobothrida, A. galli, H. gallinarum, A. cuneata, Heterakis sp., Capillaria sp. and Cheilospirura hamulosa.
The intestinal and caecal walls showed thickening, mucosa and nodular formations caused by nematodes, A. galli and H. gallinarum.A similar report was made by Rabbi et al. (2006), Bsrat et al. (2014) and Salam (2015).Most of the parasites are restricted to small intestines generally favouring absorption of nutrients through their body surface (Adang et al., 2010).However, more in-depth histopathological studies are required.

Conclusion
The current study documented that the GIT of chicken can be considered as a potential reservoir for a diverse variety of GIH infections.The month-wise, season-wise, host-wise, sex-wise, host weight-wise, host temperature-wise, host pHwise, parasite-wise and types of infection-wise prevalence reported during the present study will help in understanding the parasite recruitment transmission and various factors influencing the prevalence and intensity of parasite infection.
Similarly, variations were noted in the prevalence of different parasite groups like cestode, nematode and trematode infections.The more common appearance of mixed helminth infections, and gross lesions observed in chicken during heavy infections indicated the need to take up further studies on epidemiology and histopathology to understand and implement strategies for disease management.In view of all the above facts, it can be concluded that wholesome studies of this nature would greatly help in understanding the strategies that will enhance the health status of free range country chicken and in turn safe guard human health.