Diagnosing Death with Diatoms: A Retrospective Study of Forensic Cases in Himachal Pradesh, India

Diatoms found inside the body of a drowned victim may serve as corroborative evidence in the diagnosis of cause of death. Diatom has proved to be the only golden standard for diagnosis and confirmation of drowning deaths whether the drowning was ante-mortem or post-mortem.
The study was based on the cases of death due to drowning received from three districts of Northern Range of Himachal Pradesh, India during the period of five years from Ist January, 2010 to 31st December, 2015 for diatom test. A total of 66 human cases were examined for detection of diatoms. The detailed information regarding cause of death, socio-demographic factors and other associated information was gathered. The acid digestion method accepted worldwide for diatom extraction was used.
Male victims predominated (75.75%). Most common affected age group was 21-40 years (53.02%). The youngest victim was a girl of 4 years age who drowned accidentally in a water tank, while the oldest victim being a 86 years old who fell accidently in a river. Married victims contributed to 33 (50.0%) and unmarried to 21 (31.81%). 13 (19.69%) drowning cases belonged to students followed by labourers (18.18%) and housewives (15.15%). The highest reported cases of drowning were from the rural areas (65.15%) followed by urban areas (16.66%). Majority (81.81%) of the victims drowned in fresh water. The incidences of drowning were more in water of natural flowing streams (khuds) (31.81%) followed by rivers (22.72%), nullahs/rivulets (12.12%), wells (9.09%), kuhls/water channels (7.57%), canals (6.06%), ponds (3.03%), water tanks (3.03%) and check dam, dam and waterfall in one each (4.54%) respectively. Accidental drowning was the most common cause of death (37.87%). Highest (51.51%) percentage of drowning cases was noticed during the months of monsoon/rainy season. Blood on mouth and nostrils was present in 14 (21.21%), froth from mouth, nose, larynx and trachea in 35 (53.03%) cases. Diatom-test was found positive in 62 (93.93%) cases. The results of the study revealed the occurrence of various varieties of diatoms in water bodies of northern region of Himachal Pradesh. The most common diatom genera detected were Navicula (86.36%).
The study concluded that diatoms are amongst the important biological forensic evidences in diagnosing the cause and place of death due to drowning. Gender based examination revealed higher percentage of males involved in drowning fatalities and the accidental submersion was the commonest manner of death.