The reliability and applicability of quantitative and qualitative diatom analysis in the diagnosis of drowning has been evaluated. Water and organ samples of immersion cases reported in the area covered by the Department of Forensic Medicine of the London Hospital Medical College, were analysed using both light and scanning electron microscopy. Controls included organ samples of the bodies of people who died from natural causes and exclusion of contamination. Organ samples of both immersion and control cases were prepared by chemical digestion with concentrated nitric acid. Diatoms were present in the majority of samples of organs of both immersion and control cases but there was a significant quantitative difference between the number of diatoms in control and immersion cases. Qualitative analysis of water and organ samples of immersion cases supported the diagnosis of death due to aspiration of water in approximately a third of the total of bodies found in water. It has been suggested that the present analysis can be used as basic criteria for standardization of the diatom method.

The clinical and pathologic characterisation of two fatal cases of tick-borne rickettsiosis in rural (El Valle) and urban (City of Panama) Panama are described. Clinical and autopsy findings were non-specific, but the molecular analysis was used to identify Rickettsia rickettsii in both cases. No ticks were collected in El Valle, while in the urban case, R. rickettsii was detected in Rhipicephalus sanguineus s.l., representing the first molecular finding in this tick in Panama and Central America.

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A simple and rapid method is described for processing organ and water samples for the identification of diatoms so that they can be studied and recorded for taxonomic and diagnostic purposes. Samples are treated with concentrated nitric acid; the fluid obtained is centrifuged, and its sediment is dried, coated, and examined under the scanning electron microscope. The method does not alter the morphology of diatoms and allows the study of freshwater and seawater species present in the organs of bodies found in the water, making possible the diagnosis of drowning under specific conditions.