Dissemination kinetics and pathology of canine Leptospira icterohaemorrhagiae isolate in a guinea pig infection model

ABSTRACT

Despite significant progress made in elucidating the mechanism of acute human leptospirosis in different organs, there is a paucity of information in organs such as the heart, pancreas, brain, and adrenal gland. This study was designed to establish leptospire dissemination kinetics and patho-morphological changes associated with these orangs in the guinea pig infection model using cultural isolation (CI), polymerase chain reaction (PCR), Warthin Starry silver stain (WSss), immunohistochemistry (IH), and transmission electron microscopy (TEM). Twenty guinea pigs were inoculated intra-peritoneally with a low dosage of 1 × 10⁷ Leptospira interrogans serovar Icterohaemorrhagiae and 10 as control using distilled water. The guinea pigs were sacrificed at post-infection day (p.i.d.) ½, 1, 3, 5, and 7 followed by the harvest of the brain, pancreas, adrenal gland, heart, lungs, liver, kidneys, and spleen for CI, PCR, HE, WSss, IH, and TEM evaluations. The study revealed early dissemination of Leptospira organism in the brain, heart, pancreas, and adrenal gland and exerted various histopathological changes that were not explicitly elucidated in previous studies. This study revealed that the virulent pathogenic isolate of Leptospira organism obtained from clinically infected dog mimicked the same clinical manifestations, gross and histopathological changes especially in organs that were not previously evaluated.

KEYWORDS:

• Leptospira infection
• guinea pig
• dissemination kinetics
• histopathology
• immunohistochemistry
• transmission electron microscopy

Acknowledgments

The authors of this manuscript would like to offer their profound gratitude to Mrs. Erna van Wilpe and Dr. L Du Plessis at the electron microscopy unit, Department of Veterinary Anatomy and Physiology, University of Pretoria South Africa, Onderstepoort for their technical help. We are also indebted to Prof. Hartkreel of the Royal Tropical Institute, Amsterdam, the Netherlands who graciously offered the monoclonal antibodies used in this study.