Diatom Analysis and Postmortem Changes in a Rabbit Model: A Comparative Study of Marine and Freshwater Drowning

Abstract

The diatom test is a valuable forensic tool for diagnosing drowning, but its reliability can be influenced by the drowning medium. Furthermore, differential postmortem changes in marine versus freshwater environments are not fully characterized, potentially affecting the interpretation of evidence. This study aimed to compare diatom recoverability from organs and postmortem changes in rabbits drowned in marine versus freshwater ecosystems. Based on water sample analysis, the drowning mediums exhibited significant variation, with marine sites Pirate and Malindi beaches having the highest diatom concentration (2000±231 and 2000±195 cells/mL, respectively), followed by Kilifi bay (1500±147 cells/mL) and the freshwater control having the lowest (800±102 cells/mL). In rabbit drowning models, a significantly higher concentration of diatoms was recovered from the lungs of marine-drowned rabbits compared to freshwater, with Kilifi bay yielding the highest diatom count (3000±600 cells/mL). Furthermore, post-mortem body weight gain was significantly greater in fresh water drowning (22.64%) than in marine water (up to 13.61%), and distinct patterns of temperature decrease and external decomposition were observed between the two mediums.