Combined use of microscopic and molecular techniques to detect aquatic microorganisms in drowning-related cases and exploring the risk factors over a 6-year period (2018-2023) in Hungary.

Drowning is one of the leading causes of unintentional injury deaths. To deepen the comprehension of drowning epidemiology in our retrospective study, we analyzed 263 drowning cases across 12 distinct counties of Hungary in a six-year period. The epidemiological data of our study showed many similarities to other countries worldwide, except for the age distribution among drowning victims. In Hungary, the most susceptible age groups for both sexes were from 51 to 70, and a small number of children died from drowning. Males have a three times higher death rate than women. We can observe most drowning cases during the summer period. Concerning the different waterbody types, most drowning incidents occurred in rivers and lakes. An age-old problem of forensic medicine is the diagnosis of true drowning, respiratory impairment from submersion/immersion in liquid. The presence of waterborne microorganisms in the systemic circulation can corroborate this diagnosis. The traditional method is the microscopic identification of diatom shells, but recently, PCR-based techniques have also been employed. Our investigation compares the results of these methods. Combining the two methods improved detection, yielding a 2.6-fold increase in positive results (from 63 to 164 cases). Overall, the diatom test was positive in 23.95 % of systemic organ samples but using both methods together increased positive detection to 62.36 %, significantly reducing cases considered as negative.