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Pathogenic potential of Listeria monocytogenes isolated from cattle faeces in Adoekiti

M.A. Oyinloye, O.M. David, O Famurewa

 

Abstract

Listeria monocytogenes is an opportunistic food-borne pathogen causing listeriosis especially among immune-compromised persons. Its high rate of morbidity and mortality has classed the organism among the top watch list in foods. It is known to produce several virulence factors which aid its survival in harsh conditions and its dissemination within host cells. The pathogenicity of L. monocytogenes, isolated from cattle faeces in Ado-Ekiti, was determined in Wister albino rats for two weeks and the relative virulence was calculated. Rats were challenged with isolates producing listeriolysin O and phospholipase orally, intraperitoneally and subcutaneously. Biochemical parameters and haematoxylin and eosin (H and E) stained sections of selected organs were examined for significant changes (p < .05) and histopathological effects post-experiment. Relative virulence was recorded at 0% with rats showing no signs of infection or death. However, significant changes in total protein, lipid profile and some selected antioxidant enzymes, as well as cytological changes in the examined H and E sections of organs showed that an infection had occurred. Bacteria may have however been eradicated by the immune-competent rats. This study therefore concludes that isolates may be pathogenic especially for persons tagged ‘high risk’ due to low immunity.

Keywords:  L. monocytogenes, listeriosis, pathogenicity, histopathology, cattle feaces

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Pathogenic potential of Listeria monocytogenes isolated from cattle faece in Ado Ekiti

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Lateral geniculate nucleus histopathology in the rat experimental model of African trypanosomosis

C.I. Maina, G.M. Ng’wena

 

Abstract

Trypanosomosis is an infectious disease of humans and animals characterized by sleep/wake disturbances and disruptions in other circadian rhythm activities. The disease is caused by protozoan parasites of the genus Trypanosoma and transmitted by the bite of infected tsetse flies of the Glossina species. Although trypanosomosis has a well knownaetiology, histopathological studies on brain regions involved in the control of circadian rhythms are scanty. Lateral geniculate nucleus works in conjunction with the suprachiasmatic nucleus, the master circadian rhythm pacemaker, in regulating circadian rhythms. The purpose of this study was to investigate the effect of T.b.brucei infection on the histology of the lateral geniculate nucleus, a brain region that can serve as an alternative secondary circadian rhythm pacemaker when the master pacemaker fails. Twelve control and twelve experimental male albino rats were used in this study. The experimental rats were inoculated intraperitoneally with 0.2ml of infected blood containing 1 x 104T.b.bruceiparasites. The infected animals were allowed to go through the full course of infection and sacrificed when they were in extremis. Each rat was decapitated and the brain immediately extracted from the skull. The brain was fixed in 10% buffered neutral formalin for at least 48 hours. The brain was later removed from the formalin solution and a coronal section made. The coronal section was processed histologically and stained using the haematoxylin and eosin method. The stained slides were observed under a microscope and photomicrographs taken. Histological alterations, including tissue degeneration, infiltration and proliferation of cells, and perivascular cuffing were observed in the lateral geniculate nucleus of infected rats. Lateral geniculate nucleus cannot, therefore, serve as an alternative secondary circadian rhythm pacemaker during trypanosome infection.

Keywords: Trypanosomosis, Lateral geniculate nucleus, Histopathology, Circadian rhythm

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Lateral geniculate nucleus histopathology in the rat experimental model of African trypanosomosis