Fifteen (15) guinea pigs were experimentally infected with Leptospira icterohemorrhagiae serovar Lai strain
Langkawi, a new strain that was isolated from a human leptospirosis patient. Hematoxylin and Eosin ((H&E) staining
showed haemorrhages, congestion and oedema in all internal organs examined (lungs, liver, spleen and kidneys) with
inflammatory cell infiltration characterized by neutrophils, lymphocytes and macrophages. Hydropic degeneration and
cell necrosis were also common in our findings. Leptospires were detected starting Day 2 p.i by silver staining and
Transmission Electron Microscopy (TEM). Rise in antibody titres started on Day 5 p.i and leptospiral DNA was
detected beginning Day 3 in the kidneys and Day 5 in the liver by Polymerase Chain Reaction (PCR) assay. The
findings illustrated the pathogenesis of leptospirosis in guinea pigs which disclosed them as a suitable animal model for
demonstration of clinical symptoms of leptospirosis and pathological changes after being infected with Leptospira
icterohaemorrhagiae serovar Lai strain Langkawi, particularly pulmonary haemorrhages, a leading cause of mortality
in human leptospirosis.