Clinico-Pathological Investigation of Coccidiosis in Naturally Infected Sasso T44 Chickens

INTRODUCTION

The poultry industry in Ethiopia is primarily focused on chicken, with a limited presence of other poultry species.^[1] The country’s chicken population is estimated at 56.06 million, comprising indigenous, hybrid, and exotic breeds.^[2] Poultry farming significantly contributes to food security and the economy, with around 80% of Ethiopians relying on it as a source of income.^[3] The poultry value chain offers significant job opportunities for entrepreneurs, particularly enhancing economic prospects for women. This sector has empowered many women by providing them with increased opportunities for employment and income generation.^[4]

Ethiopian chicken rearing practices are categorized into three production systems based on various factors. There are large commercial, small-scale commercial, and village or backyard poultry production systems.^[5] Efforts to improve poultry productivity have involved the importation of different breeds of exotic chickens and the introduction of improved layer-type chickens to smallholder farmers. Challenges with adopting exotic chicken breeds include a lack of sustainable supply, health issues, and problems with nutrition and predation.^[6-9]

Among the different private suppliers involved in the sector, currently, Ethiochicken stands as one of the leading poultry companies in East Africa. The company specializes in producing and delivering improved breeds of day-old chickens and blended poultry feed to its customers. In Ethiopia, it distributes dual-purpose and layer chicken breeds, mostly the robust and multi-colored Sasso T44 breed. Sasso T44 is a dual-purpose type breed; it is easy to manage and productive in extensive scavenging and semi-intensive rearing conditions.^[10,11]

However, the industry continuously faces challenges due to various factors such as infectious diseases, shortages of formulated feed, and farming equipment. The most prevalent poultry diseases in Ethiopia include Newcastle disease, infectious bursal disease, coccidiosis, and other parasitic disorders.^[3,12,13] Coccidiosis, in particular, has a significant impact on poultry production, with a wide prevalence range and substantial economic costs for farmers.^[14,15] Coccidiosis is a parasitic disease caused by the protozoan Apicomplexa called the genus Eimeria, which affects the intestinal tract of birds of all ages.^[16,17] It is characterized by bloody diarrhea, weight loss, ruffled feathers, somnolence, huddling together, and production reduction.^[16] Eight known species of Eimeria can affect chickens, such as Eimeria acervulina, Eimeria brunetti, Eimeria maxima, Eimeria mitis, Eimeria necatrix, Eimeria praecox, Eimeria mivati, and Eimeria tenella.^[16,18] E. necatrix, E. maxima, and E. tenella are endemic in Ethiopia and affect all ages and breeds of chickens.^[19]

Although Coccidia prevalence has been reported in various areas, limited data exist on the relationship to clinico-pathology. Understanding the clinical and pathological aspects of the diseases gives insight into the nature of the diseases and helps to design measurement approaches. Therefore, this study aimed to investigate the impact of Coccidia infection on Sasso T44 chickens by analyzing hematological, gross, and histopathological changes.

MATERIAL AND METHODS

Study area

The study was conducted in Ayikel town, Central Gondar zone, in the northwestern part of Ethiopia [Figure 1]. It is located 809 km far away from Addis Ababa and 56 km from Gondar town, at coordinates of 12° 33’ north latitudes and 37°04’ east longitudes. The altitude is 2146 m above sea level and receives an annual rainfall of 102.6 mm. It has an annual minimum and maximum temperature of 15.08°C and 26.92°C, respectively.

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Figure 1:

Map of the study area.

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RESULTS

Clinical examination

Clinical and physical examinations on suspected chickens were presented with bloody diarrhea, depression, weakness, anorexia, ruffled feathers, emaciation, and death [Figure 2].

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Figure 2:

Clinical signs of chickens (a) huddling together, depression, ruffled feathers, and a mix of white and red diarrhea (blue arrow), and (b) red diarrhea, bloody diarrhea (orange arrow).

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Gross pathological examination

E. tenella, E. maxima, and E. Brunetti were identified from different segments of the intestine. The results of the necropsy revealed severe hemorrhagic typhlitis and distended and petechial hemorrhages in several areas of the lower intestine. The caeca were highly inflated and petechial bleeding when viewed grossly without opening the gut. However, when the caecum’s mucous membrane was exposed, isolated hemorrhagic patches were also visible. It was common to find a thickened caecum that displayed necrosis and sloughing of the epithelium, an expansion of the caecum with clotted blood, hemorrhagic corrugated mucosa, and a dilatation of the caecum with consolidation [Figures 3 and 4].

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Figure 3:

Gross lesion of Eimeria tenella-infected dual purpose Sasso chicken caeca, (a) congested and distended loop of left side ceca, (b) caecal core (sloughed mucosal surface joined to the bloody material), on removal of the material the underneath caecum was severely hemorrhagic due to E. tenella, (c) severe congestion, dilatation and filled with bloody contents with friable caecal wall and petechial hemorrhage looking grossly, and (d) severe hemorrhagic typhlitis with clotted blood in the mucosa of blind ceca.

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Figure 4:

Gross lesion of Eimeria tenella, Eimeria brunetti, and Eimeria maxima infected dual Sasso T44 chicken intestine. (a) Necrotized and hemorrhagic blind ceca due to E. tenella, (b) Petechial hemorrhage, orange viscous mucous exudate in the lumen and thickened ilium mucosa due to E. maxima, (c) corrugated mucosa of cecum due to E. tenella, and (d) petechial hemorrhage in the rectum mucosa due to E. brunetti.

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Parasitological examination

The presence of oocysts was confirmed using wet smears from mucosal scraping samples and the flotation technique by taking fecal material directly from the rectum. After confirming the presence of oocysts, sporulation was induced using a 2.5% potassium dichromate solution to check whether it was an Eimeria oocyst or other protozoal parasite by checking the number of sporocysts and sporozoites on it [Figure 5].

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Figure 5:

Eimeria oocyst identification by using different techniques, (a) Oocysts were identified by the fecal flotation technique at a magnification of 10x, (b) oocysts were identified under a magnification of 400x, (c) oocysts were determined using wet smears from cecal mucosal scraping at 40x magnification, (d) sporulated Eimeria oocyst contains four sporocysts, while each sporocyst is dizoic, i.e., it contains two sporozoites, four of which each have 2 sporozoites (400x).

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Histopathological examination

Histopathologically examined intestinal tissue samples showed different developmental stages of Coccidia, including oocysts, schizonts, merozoites, macro-, and microgametes. The epithelial cells, the villi, and the crypts were highly necrotized and invaded with developmental stages of Coccidia and a high number of inflammatory cells. High numbers of inflammatory cells were also seen in the lamina propria. The mucosal layer was sloughed and eroded. Hemorrhages, congestion, edema, and dilation of intestinal glands were also observed [Figures 6 and 7].

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Figure 6:

Histopathological changes in dual-purpose Sasso chickens due to E. tenella infection, (a) the lumens of crypts are filled with intact and degenerating oocysts (black arrow), and the epithelial cells of the crypts exhibit different developmental stages of E. tenella (black arrowhead: Chevron) and edema (blue arrow) (Hematoxylin and Eosin [H&E] stain 400x), (b) Large meronts containing merozoites (white arrow) (H&E stain 400x), (c) different stages of Schizonts in the cecal mucosa (down arrow) (H&E stain 600x), (d) different developmental stages in the mucosa of the cecum (notched right arrow), and filling of the lumen of the cecum with caseous debris (cecal core) (black arrowhead: Chevron) (H&E stain 1000x).

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Figure 7:

Histopathological changes due to E. tenella, E. brunetti and E. maxima, (a) disintegration of the crypt gland due to E. tenella (white downward arrow) (H&E stain 1200x), (b) atrophy of the villi (black downward arrow) and hemorrhage in the mucosa of the ilium (upper arrow) due to E. maxima (H&E stain 500x), (c) blunt termination (upper black arrow) and hemorrhage in the submucosa of the rectum (left arrow) due to E. brunetti (H&E stain 500x), (d) microgametes (red arrow) and macrogametes (black arrow) in the submucosa of the cecum due to E. tenella (H&E stain 1500x).

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DISCUSSION

Coccidiosis is one of the main problems in poultry farming. Eimeria species is the main causative agent of coccidiosis, which widely occurs throughout Ethiopia. Heavy morbidity and mortality due to coccidiosis have significantly affected the poultry industry, especially in the intensive deep litter management system. Therefore, pathological investigation of coccidiosis is significant to be aware of its impacts and to take preventive measures.

In the current investigation, E. tenella, E. maxima, and E. brunetti were identified. Similarly, Lobago et al.^[29] identified E. brunetti in the Kombolcha Poultry Multiplication and Research Center, Chanie et al., Jimolu, and Lobago et al.^[29-31] reported E. tenella in Tiyo Woreda, Arsi Administrative Zone of Oromia Regional State, and Adamu et al.^[32] found E. tenella and E. brunetti from a small-scale grill farm in Debre Zeit, Ethiopia. Postmortem examination revealed thicker, congested orange mucus and an edematous intestinal wall with petechial to severe bleeding. Enlarged and distended caecal pouch with clotted blood, caecal core, corrugated mucosa, and hemorrhagic typhlitis were also observed, which was consistent with the findings of Adamu et al. and Yohannes et al.^[32,33]

Histopathologically, numerous oocytes, schizonts, gametocytes, and merozoites invaded the mucosal and submucosal layers, loss of enterocytes, hemorrhage, and necrosis of the mucosal layer, disintegration of mucosal glands, desquamation, and blunting of villi were observed. This result is supported by the reports of Sharma et al., Melkamu et al., and Shilpa Sood et al.^[34-36] This led to hemorrhage of the intestine and reduced the efficiency of the small intestine for absorption of nutrients.

The pathological effects of E. tenella and E. maxima on poultry were studied by various researchers^[32,37,38] which reported that the second generation schizont of E. tenella caused severe damage to the caecal glands, mucosa, and muscularis layer, resulting in tissue damage and bloody diarrhea. On the other hand, E. maxima was found to induce villous atrophy, epithelial cell proliferation, hemorrhage, and submucosal gland dilation, as observed by Sharma et al. and Zulpo et al.^[34,39]

In the conducted study, it was found that coccidiosis caused by E. tenella, E. maxima, and E. brunetti resulted in a significant reduction in total blood cell count and PCV levels. This aligns with previous research by Habibi et al., Melkamu et al., Muhammad et al., and Umar et al.^[36,40-43] In addition, the study indicated the presence of macrocytic normochromic anemia, contradicting previous findings of normocytic hyperchromic or normocytic hypochromic anemia.^[43-45] The observed anemia may be attributed to severe hemorrhages, stimulating the release of immature erythrocytes by the bone marrow.

Higher values of MCV in present study indicated macrocytic anemia. This might be due to severe hemorrhages which stimulate bone marrow to release regenerative forms of immature erythrocytes in circulation. Higher values of MCV in the present study indicated macrocytic anemia. This might be due to severe hemorrhages which stimulate bone marrow to release regenerative forms of immature erythrocytes in circulation.

The differential WBC count on Dual Sasso breeds infected by E. tenella, E. maxima, and E. brunetti revealed increased numbers of lymphocytes, monocytes, eosinophils, and heterophils compared to the reference value indicated by Thrall et al.^[25] These findings align with Adamu et al., El-Shazly et al., Khaligh et al., Melkamu et al., Oljira et al., and Umar et al.,^{[32,36,43,46-48]} indicating an increment in peripheral blood leukocytes (PBL) in response to Eimeria species infection in chickens. However, in contrast, Nonkookhetkhong and Chalalai, Petrone et al., and Zulpo et al.^[39,49,50] reported decreased eosinophil and heterophil counts in E. tenella-infected groups, primary infections showed biphasic increases in PBL numbers and significant changes in polymorphonuclear cells, lymphocytes, and monocytes counts.

The chicken’s increased lymphocyte count may be due to the induction of an immune response to infection, as lymphopoiesis increases as the first step of defense. Heterophils, a type of granulocytic leukocyte, act as the initial defense against pathogens. Heterophilia and monocytosis are linked to acute and chronic inflammatory responses, respectively. Eosinophilia is associated with parasitic infestation and is rarely reported in chickens, but may be linked to parasitism (e.g., mites, intestinal parasites, and parasites with tissue migration^[22,51]).

The serum analysis in this study revealed elevated ALP and ALT levels, normal AST levels, and decreased protein levels compared to the normal reference values.^[25] These findings align with El-Maksoud et al. and Melkamu et al.,^[36,52] but contradict the findings of Adamu et al. and AL-Saegh.^[32,37] It also argues with the finding of Patra et al.,^[53] who reported that the ALP level was significantly reduced in the affected birds, which is indicative of damage to the bone marrow with severe growth depression, as ALP is known to rise during active growth.

The serum TP level is decreased, which is similar to the report of El-Maksoud et al., Freitas, and Hirani et al.,^[52,54,55] who presented that a significant reduction in total serum protein different Eimeria species. The reduced TP level may be attributed to factors such as stress, liver alterations, and nutritional malabsorption. The study also suggests that increased ALP activities could be linked to excessive blood cell production in the bone marrow, while elevated ALT levels may indicate hepatocellular damage and metabolic alterations.

CONCLUSION

The study found that Eimeria infection severely affected Sasso chickens, causing extensive tissue damage, hemorrhage, and significant drops in red blood cell count and Hb levels.