Proliferative enteropathy (Lawsonia intracellularis) outbreak in rabbits in Brazil

Abstract

RESUMO.-[Surto de Enteropatia Proliferativa (Lawsonia intracellularis) em coelhos no Brasil.] Descreve-se um surto de infecção por Lawsonia intracellularis em coelhos em Mendes, Estado do Rio de Janeiro. A doença manifestou-se, de forma aguda (24-48 horas), com sintomatologia caracterizada por diarréia marrom ou esverdeada, e desidratação. Ocasionalmente, os animais morriam um dia após o início da diarréia, sem apresentar outros sintomas. À necropsia verificou-se íleo proeminente, firme, com parede muito espessada, progressivamente dilatado no sentido caudal e com aspecto algo reticulado perceptível através da serosa. A mucosa espessada tinha aspecto finamente corrugado e superfície brilhante. A válvula íleo-cecal e imediações do ceco encontravam-se um pouco edemaciadas e irregulares. Occasionally, the animals died one day after the onset of diarrhea, without showing any other clinical signs. At necropsy, the ileum was prominent, firm and had a thickened wall; it was dilated in the caudal direction and had a somewhat reticulated appearance, perceptible through the serosa. The thickened mucous membrane had finely corrugated aspect and a shiny surface. The ileocecal valve and surrounding areas were slightly edematous and irregular. The Peyer's patches were sometimes more evident. There was moderate enlargement of the mesenteric lymph nodes. The histological examination revealed different degrees of hyperplasia of the epithelial cells of intestinal crypts consisting of poorly differentiated, hyperchromatic cells with high mitotic index, arranged in a pseudostratified layer which, in some cases, reached the apical portions of the villi. The inflammatory infiltrate between the hyperplastic epithelial cells was composed of lymphocytes, plasma cells, macrophages, some eosinophils and globular leukocytes. Silver impregnation revealed large numbers of bacteria with morphology of the genus Lawsonia in the apical pole of cryptal enterocytes. These bacteria reacted positively to a Lawsonia intracellularis polyclonal antibody by the avidin-biotin immunohistochemistry method.

Proliferative enteropathy caused by Lawsonia intracellularis in rabbits in Southern Brazil

“…In rabbits three histological lesions pattern of enteritis associated with L. intracellularis has been described: proliferative, histiocytic, and necrosuppurative (Schoeb & Fox, 1990). As observed in other species, crypt proliferation is commonly severe and leads to changes in the ratio of villi and crypt cells, shifting the ratio of 3:1 to 1:1 (Peixoto et al, 2008). However, in cases with an acute presentation, such as the ones described in this study, the proliferation may be little or moderate.…”

“…However, in cases with an acute presentation, such as the ones described in this study, the proliferation may be little or moderate. The acute course that led to death in 24-48 hours was already described in an outbreak of L. intracellularis in rabbits, and the animals only showed diarrhea and dehydration, and the ileum displayed thickness and firm consistency (Peixoto et al, 2008). Another author infers that proliferative lesion is the primary feature in rabbits (Sampieri et al, 2013); nevertheless, it can vary from histiocytic enteritis and necrosuppurative (Schoeb & Fox, 1990).…”

“…Proliferative enteropathy (PE), also known as ileitis, is a disease caused by Lawsonia intracellularis (McOrist & Gebhart, 2012), an obligate intracellular vibrioid, gram-negative bacterium that colonizes immature enterocytes in the intestinal crypts and causes enterocyte hyperplasia and prevents the differentiation of infected enterocytes leading to thickening of the intestinal mucosa, and resulting in malabsorption syndrome (Pusterla, Mapes, & Gebhart, 2012;Vanucci & Gebhart, 2014). The intestinal colonization and clinical disease caused by this microorganism have been reported in several species such as rats, ferrets, hamsters, and guinea pigs (Percy & Barthold, 2007), horses (Vanucci & Gebhart, 2014), rabbits (Peixoto, França, Ribeiro, Bezerra, & Driemeier 2008), and endemic in pig herds (McOrist & Gebhart, 2012).…”

“…In the acute presentation, there are reports of high mortality due to diarrhea in neonatal, young, and adult rabbits (Peixoto et al, 2008). Otherwise, rabbits with chronic lesions may present thickening of the small intestine (Percy & Barthold, 2007).…”