Pigeons, as commensal birds, live alongside humans in urban environments and serve as a source of food, a hobby, a symbol of religion, and a subject of experimentation (Alkharigy et al., 2018). Pigeons can be easily found in both rural and urban centers (Gicik & Arslan, 2001). According to an estimation, there are 170 – 340 million pigeons residing in cities worldwide (Haag-Wackernagel & Bircher, 2010). Since ancient times, pigeons and humans have coexisted, with humans utilizing them as a food source and for experimental purposes (Sari et al., 2008). Pigeons are a valuable source of essential proteins for people because, compared to other birds, they gain weight quickly, their meat requires minimal management, they are easy to breed, and they are palatable (Mohamed El-Dakhly et al., 2016). In Pakistan, pigeons are almost ubiquitous and inexpensive, making them ideal for laboratory experiments and research (Tanveer et al., 2011). In the Malakand region, pigeons are widely traded and sold (Khan et al., 2018).
Pigeons transmit numerous parasites and pathogens to different flocks (Opara et al., 2012). They can transmit up to 30 different diseases to poultry, serving as a source of various zoonotic diseases for people (Msoffe et al., 2010). Birds can be parasitized by various ecto- and endoparasites, including cestodes, trematodes, nematodes, acanthocephalans, protozoans, and arthropods (Sivajothi & Reddy, 2016; Alkharigy et al., 2018) when birds are kept for prolonged periods, increasing their exposure to parasites, which can lead to serious health problems or even death (Krone & Cooper, 2002). Diseases such as Newcastle disease, coccidiosis, cryptococcosis, encephalitis, histoplasmosis, Salmonella food poisoning and toxoplasmosis can affect pigeons (Bahrami et al., 2015). Different parasites can delay pigeon development, growth, and productivity, and may also cause death, especially in newborn pigeons (Abdullah et al., 2021). For those avian hosts, which share a common parasitic fauna with pigeons, act as carrier or reservoir hosts, and are an important source of infection (Borji et al., 2012). Humans become infected with fecal dust from cages or other sites contaminated with parasitic pigeon urine, dried feces, and droppings (Eljadar et al., 2012). Parasitic fauna badly affects the intestine, causing various consequences such as toxic effects, mechanical injuries, metabolic effects and growth impairment (Shaikh et al., 2016). Some studies have demonstrated the presence of hemoparasites and gastrointestinal parasites (Sol et al., 2000). The majority of pigeons are infected with Ascaridia columbae and Raillietina tetragona (Shaikh et al., 2016). In domestic pigeons, helminths are involved in high mortality and infection rates. In the production of commercial pigeons in Pakistan, helminths are considered one of the critical weaknesses (Tanveer et al., 2011) and can cause serious damage to host tissue (Hoste, 2001).
The pigeons infected with C. infundibulum, R. cesticillus, and C. digonopora had diarrhea, weakness, emaciation, and stunted growth. Histopathological alterations in the intestine of pigeons due to C. digonopora disfigure the villi and glands. At the same time, R. cesticillus and C. infundibulum cause degradation of villi, holes in muscle layers, and dysfunction and distortion of glands (Soomro et al., 2024).
In the intestine of some pigeons infected with Raillietina species, histopathological changes may be observed (Shaheen et al., 2005), such as ulceration, destruction of the epithelial secretory gland, lymphocyte and macrophage infiltration, enteritis (Abed et al., 2014), and intestinal nephritis (Panchbhai et al., 2007). In young pigeons, the complications can lead to death (Basit et al., 2006). Gastrointestinal parasites are involved in robbing the host of minerals, nutrients, and vitamins, which in turn cause serious conditions such as immune system dysfunction, abnormal growth, enteritis, decreased reproductive efficiency, and may sometimes cause death (El-shahawy & Abou Elenien, 2015).
Pigeon lice, also known as chewing lice, are of major species including Columbicola columbae, and C. tschulyschman (the wing lice) found between the wing and barbs of tail feathers. In contrast, Campanulotes compar (the body lice) are found in downy feathers (Alali et al., 2020).
As there is limited documented data regarding ecto- and endoparasites in pigeons, the current study aimed to investigate the association between histopathological changes in the intestinal tract and helminth parasites.
This study was performed in Malakand region Pakistan (latitude; 34°33′56″ N, Longitude; 71°55'49" E. Batkhela (34°37'12.00” N, 71°58'12.00” E and District Swat (35°22'59.99" N, 72°10'60.00" E) Khan et al. (2018). Here, the summers are sweltering and clear, while winters are cold and partly cloudy. The annual highest and lowest temperatures here are 43.88°C and 1°C, respectively. Hills and mountains highly dominate the topography of this area.
The pigeons were purchased from the local market of Chakdara and transported to the Parasitology Laboratory at the University of Malakand. They were fed freshwater with wheat and grain.
Pigeons of both sexes were screened for ectoparasites. Their skin, feathers, and tails were examined, and parasites were collected through hand-picking and brushing, and then placed in 10 % neutral buffered formalin for preservation. The preserved specimens were then brought to the parasitology laboratory at the University of Malakand and examined microscopically for identification. The remaining parasites were preserved in 10 % neutral buffered formalin for future studies. The sex and age of the pigeons were recorded.
The pigeons were placed in a vacuum chamber with cotton wool soaked with chloroform (Kamal et al., 2020). Dissection was performed according to the method described by Khan et al. (2018). The intestine was separated from other parts and placed in a Petri dish containing normal saline. It was then cut longitudinally using a blade and opened to expose contents for parasite examination. The detected parasites were carefully separated from the intestinal contents using a fine brush and forceps. The collected cestodes and nematodes were then preserved and prepared for microscopic examination as previously described (Wakid et al., 2025).
For histopathological examination, the intestines of both infected and uninfected pigeons were cut into parts (duodenum, jejunum, ileum, rectum and caecum) and preserved in 70 % alcohol. Aspreviously described (El-Kady et al., 2024; Wakid et al., 2023), tissues from each group were isolated and fixed in 10 % formalin, dehydrated in ascending concentrations of ethanol, and then embedded in paraffin. The paraffin blocks were sectioned at 5 μm and stained with hematoxylin and eosin (H&E), and then examined by light microscopy to assess histopathological changes and the degree of infection.
Parasites were identified according to the key provided by previous investigations (Alshaebani, 2008; Soulsby, 1982; Alali et al., 2020; Khan et al., 2018).
Data were analyzed using the chi-square test in GraphPad version 5. A p-value less than 0.05 is considered statistically significant at a 95 % confidence interval.
A total of 50 pigeons were examined for ectoparasite infection. Of the examined pigeons, 30 were male and 20 were female. A total of 36 pigeons were infected, representing an infection rate of 72 %. The infection rate was 83.33 % (25/30) in males and 55 % (11/20) in females (p-value 0.189). Two different species of lice were detected. Of the total infected pigeons, 30 (83.33 %) were infected with C. tschulyschman and 6 (16.66 %) with C. compar (p-value < 0.001). There was no double infestation, as all the pigeons were infected with only one species. No ticks, mites, or flies were detected. See Table 1, Table 2, and Fig. 1.
The detected lice. (A) Ventral side of C. compar (10X); (B) Dorsal side of C. compar (5X); (C) Male of C. tschulyschman (10X); (D) Female of C. tschulyschman (10X).
Prevalence of ectoparasitic infestation in relation to sex of the pigeons.
| Gender | Infected, N (%) | Uninfected, N (%) | P-value |
|---|---|---|---|
| Male (30) | 25 (83.33) | 5 (16.66) | 0.189 |
| Female (20) | 11 (55) | 9 (45) | |
| Total (50) | 36 (72) | 14 (28) |
Prevalence of lice species in domestic pigeons.
| Parasite | Infected, N (%) | Uninfected, N (%) | Total, N (%) | P-value |
|---|---|---|---|---|
| C. tschulyschman | 30 (83.33) | 6 (16.66) | 36 (100) | < 0.001 |
| C. compar | 6 (16.66) | 30 (83.33) | 36 (100) |
A total of 21 domestic pigeons were examined and dissected for the presence of both ecto and endoparasites. As shown in Table 3, the examined males and females were 15 and 6, respectively, with a total of 15 infected pigeons representing an infection rate of 71.4 %. Of the infected pigeons, 12 were males with an infection rate of 80 %, and 3 were females with an infection rate of 50 % (P-value 0.389). As shown in Table 4, of the total infected pigeons, 12 were infected with 6 different species of cestodes, including two Raillietina species: R. tetragona (Fig. 2B) and R. micracantha (Fig. 2C); two Cotugnia species: C. digonopora (Fig. 2D) and C. intermedia (Fig. 2E); one Bothriocephalus species: B. columbae (Fig. 2F); and one Choanotaenia species: C. infundibulum (Fig. 2G). Three pigeons were infected with one nematode, A. columbae (Figs. 2H and 2I).
The detected endoparasites. (A) The dissected intestine showing the released cestodes; (B) R. tetragona; (C) R. micracantha; (D) C. digonopora; (E) C. intermedia; (F) B. columba; (G) C. infundibulum; (H) A. columbae (anterior part); (I) A. columbae (middle region).
Demographic characteristics of the samples studied.
| Gender | Infected, N (%) | Uninfected, N (%) | P-value |
|---|---|---|---|
| Male (15) | 12 (80 | 3 (20) | 0.389 |
| Female (6) | 3 (50) | 3 (50) | |
| Total (21) | 15 (71.4) | 6 (28.5) |
Prevalence of nematode and cestode parasites infection, based on the sex of the 21 pigeons examined.
| Parasites | Male, N (%) | Female, N (%) | Total, N (%) | P-value |
|---|---|---|---|---|
| R. tetragona + R. micracantha | 9 (42.85) | 3 (14.28) | 12 (57.1) | 0.502 |
| C. digonopora | 5 (23.8) | 0 | 5 (23.8) | |
| C. intermedia | 1 (4.76) | 1 (4.76) | 2 (9.52) | |
| B. columbae | 1 (4.76) | 1 (4.76) | 2 (9.52) | |
| C. infundibulum | 2 (9.52) | 1 (4.76) | 3 (14.28) | |
| A. columbae | 3 (14.28) | 0 | 3 (14.28) |
The pigeon intestinal tract is a multi-layered tube, divided into the duodenum, jejunum, ileum, rectum, and caecum, containing a serosal layer, a longitudinal muscular layer, a circular muscle layer, a submucosal layer, and a mucosal layer. Numerous folded finger-like tissues extending into the lumen of the small intestine are known as villi. The lamina propria is in the interior of the villi, beneath the epithelial cells.
Histopathological examination of intestine infected with cestodes revealed several pathological changes (Figs. 3A–E), such as destruction and shrinkage of the duodenum, aggregation of lymphocytes as inflammatory reaction in the serosa of small intestine, atrophic hyperplasia in ileum, presence of inflammatory lymphocytic cells of lamina propria, atrophy, inflammation and distortion of intestinal villi and glands, inflammation in rectum and caecum, infiltration of inflammatory lymphocytes at muscularis externa, desquamation of the lining of epithelium inside the lumen with erosion, and the loss of the typical intestinal architecture.
Photomicrograph of intestine tissue sections (stained with H & E), at 40X. (A) Duodenal part infected with cestodes, shows destruction and shrinkage; (B) Atrophic hyperplasia in the infected ileum with cestode; (C) Rectum infected with cestodes shows inflammation of villi; (D) Inflammation in infected rectum with cestodes; (E) Inflammation in caecum infected with cestode; (F) Death of cells in infected intestine with nematode; (G) Migratory tunnels formation in intestine infected with nematode; (H, I) Intestine infected with nematode shows infiltration of lymphocytes, inflammation and histological hyperplasia.
The intestine infected with a nematode exhibited cell death, formation of migratory tunnels, lymphocyte infiltration, inflammation, and histological hyperplasia (Figs. 3F–I).
Among the fifteen infected pigeons, one male (6.66%) and one female (6.66%) showed quadruple parasitic infestation having both ecto and endo parasites (Table 5). As shown in Table 6, among the twelve pigeons infected with triple different species of cestode, 9 (75%) were males and 3 (25%) were females.
Detected quadruple parasitic infection in relation to the pigeon sex.
| Male (N=1, 6.66%) | Female (N=1, 6.66%) | P-value |
|---|---|---|
| C. tschulyschma + R. tetragona + R. micracantha + C. intermedia | C. compar + R. tetragona + R. micracantha + B. columbae | 0.158 |
Detected triple cestode parasitic infection in relation to the pigeon sex.
| Parasites | Male, N (%) | Female, N (%) | Total, N (%) | P-value |
|---|---|---|---|---|
| R. tetragona + R. micracantha + C. digonopora | 5 (41.66) | 0 | 5 (41.6) | 0.375 |
| R. tetragona + R. micracantha + C. intermedia | 1 (8.33) | 1 (8.33) | 2 (16.6) | |
| R. tetragona + R. micracantha + B. columbae | 1 (8.33) | 1 (8.33) | 2 (16.6) | |
| R. tetragona + R. micracantha + C. infundibulum | 2 (16.66) | 1 (8.33) | 3 (24.9) | |
| Total | 9 (75) | 3 (25) | 12 (100) |
The overall prevalence of ectoparasites was 72 % in the current study, which included C. tschulyschman (83.33 %) and C. compar (16.66 %). Similar findings in Iraq were reported by Alali et al. (2020), with an overall prevalence of 81 %. Khan et al. (2018) reported an 86.6 % prevalence rate of three ectoparasites in pigeons of the Malakand region, Pakistan. According to Salem et al. (2022), the prevalence of ectoparasites in Egypt was 80.3 %. A low rate of prevalence, 67 %, was investigated by Ghosh et al. (2014) for four ectoparasite species in Bangladesh. Laku et al. (2018) reported two species of ectoparasites in pigeons from Nigeria, with an infection rate of 58 %. One species of ectoparasite with a 17.6 % infection rate was observed by Natala et al. (2009) in Nigeria. Three species of ectoparasites, with a 62 % infection rate, were reported by Msoffe et al. (2010) in Tanzania. The variations in the prevalence of parasitic infestations could be due to climatic and geographical factors, their habits of living, and unhygienic environmental conditions.
Pigeons are the definitive or intermediate hosts for several parasitic helminths. Cestodes in the intestines of pigeons release their eggs and pass to the external environment, then are ingested by the intermediate hosts from pigeon droppings (feces). These ingested eggs hatch into larvae, which develop into cysticercoids. These cysticercoids then attach to the intestine and mature into adult worms. Nematodes in pigeons are transmitted directly via eggs from contaminated environmental sources (Natala et al., 2009). The severity of histopathological infection varies from region to region due to several factors, including pigeon strain, feeding behavior, habitat, and environmental factors.
In the current study, the prevalence of cestodes was noted as 80 %, including Raillietina species (57.1 %), Cotugnia species (33.28 %), and Ascaridia species (9.5 %). The same species of endoparasites were also reported by Khan et al. (2018), with a 60 % prevalence, comprising Raillietina species (60 %), Cotugnia species (13.3 %), and Ascaridia species (6.66 %) from the Malakand region. According to a study in India by Sivajothi et al. (2015), the infection rate was 72.7 % including 9 % Raillietina species and 33.3 % A. columbae. Mushi et al. (2000) reported a 75 % infection rate composed of Raillietina species and A. columbae from Sebele, Botswana. According to the study by Msoffe et al. (2010) from Tanzania, four species of endoparasites with an infection rate of 79.5 % were reported. A lower prevalence (67 %) of endoparasites was noted by Ghosh et al. (2014) in Bangladesh. Laku et al. (2018) found the presence of R. tetragona, A. columbae, and Eimeria species, with an overall prevalence of 38 % in Nigeria. Natala et al. (2009) reported an overall prevalence of 49.2 % of 6 species of endoparasites, including R. tetragona and A. columbae from Zaria, Nigeria. From Lahore, Pakistan, Tanveer et al. (2011) found the total endoparasite prevalence of 40.5 % including 32.8 % A. columbae infection. Raillietina species were the most common tapeworm infection in pigeons Kamal et al., 2020) and house crows Shah et al., 2025). And also infected crows at a 47.4 % prevalence rate (Shah et al., 2025). Typha angustata and sulphadimidine were investigated as the most effective remedy against Raillietina species in Columba livia domestica (Yousafzai et al., 2021). Sulfadimidine was treated the most effective drug against coccidiosis in wild pigeons Khan et al. (2021).
This variation is due to the extent and distribution of Raillietina species and Ascaridia species infection in pigeons are quite variable across different geographic regions. Endoparasites infections are also significantly influenced by the feeding and living behavior of their hosts, as the literature is recorded in different regions of the world. Therefore, there is a great contrast between our results and the results from other researchers worldwide. Furthermore, water and food contamination also affect the distribution of parasites, which may contribute to the variation in the results.
Various helminth parasites shows pathological consequences on pigeons, however, the extent of damage depends on the species, number and habitat of of cestode and nematode parasite, in the body of the host (Natala et al., 2009). The results of current histopathological examination showed destruction and shrinkage in duodenum, necrosis and shrinkage of serosa and submucosa, villous atrophy and migratory tunnels formation in accordance with previously reported findings (Nisar, et al., 2015). In addition to atrophic hyperplasia in ileum, agreggate of inflammatory lymphocytes at the lamina propria, inflammation of villi in the rectum, cells death, infiltration of lymphocytes, inflammation and histological hyperplasia in the intestines of pigeons infected with csetode and nematode species. These finding were also supported by the previously reported histopathological changes in the intestines of pigeons infected with Cotugnia species, which showed lymphatic reaction in the serosa of small intestine, an aggregate of lymphocytes found at lamina propria and muscularis externa of small intestine, presence of inflammatory cells of lamina propria of villi, interstitial edema and small lymphatic aggregate in dilated veins in muscularis externa (Al-Emarah & Al-Aziz Suzan, 2016). Simmilar to our results, Shaikh, et al. (2016) reported muscularis layer disintegration, migratory tunnels formation, necrosis of serosa, villus atrophy and necrosis, and infiltration of mononuclear inflammatory cells in lamina propria of intestines caused by helminth parasites.
A total of 71 pigeons were examined for ectoparasites and 21 for endoparasites. 36 pigeons were infected with two species of lice, such as C. tschulyschman and C. compar. 15 pigeons were infected with endoparasites, including 6 species of cestodes (R. tetragona, R. micracantha, C. digonopora, C. intermedia, B. columbae and C. infundibulum), and 1 species of nematode (A. columbae). Histopathological investigation showed destruction and shrinkage in duodenum, necrosis and shrinkage of serosa and submucosa, villous atrophy and migratory tunnels formation, atrophic hyperplasia in ileum, agreggate of inflammatory lymphocytes at the lamina propria, inflammation of villi in the rectum, cells death, infiltration of lymphocytes, inflammation and histological hyperplasia in the intestines. Based on current study, it is suggested to do further investigations on parasites prevalence, their inflammatory effects, zoonotic importance and public awareness about the zoonotic effects.