July 2022 – Infectious Disease Pathology and Autopsy/Forensics

Postmortem insect activity.

As inferred in the question stem, this was an individual who was found several days after an apparent suicide by gunshot out in the wilderness. As expected, the decedent was found with significant decompositional changes, including marbling, skin discoloration, and extensive maggot activity. With the integrity of the skull disrupted by the projectile, insects were more easily able to gain access for feeding and reproduction. While some species of insect will infect living tissue to lay their eggs (e.g., the botfly), adult houseflies are often attracted to open wounds and host orifices to feed and lay eggs.

This particular maggot was found along the leptomeninges of the brain and was submitted as part of the routine histopathology analysis in a typical autopsy. This cross-section satisfactorily highlights the different components of the maggot, with the internal components of the digestive tract, the outer striated muscle along its internal surface, and its surface cuticular spines, which can be most appreciated along the image’s lower-right surface. An indication that this is post-mortem activity (opposed to ante-mortem) is the noted lack of a typical immune reaction or localized cellular response to a parasitic infection.

Maggots have a surprising usefulness in forensic science. For example, the field of forensic entomotoxicology looks at the analysis of toxins and drug content in insects that feed on carrion and post-mortem tissue. This can be especially useful in instances where severe decomposition has occurred and procuring an adequate blood sample may prove difficult.¹ Additionally, there are ongoing studies examining the correlation between establishing a time of death and the present insect burden.² 

References

1. Joseph I, Mathew DG, Sathyan P, Vargheese G. The use of insects in forensic investigations: An overview on the scope of forensic entomology. J Forensic Dent Sci. 2011;3(2):89-91. doi:10.4103/0975-1475.92154
2. Ruchi S, Kumar Garg R, Gaur JR. Various methods for the estimation of the post mortem interval from Calliphoridae: A review. Egy J Forensic Science. 2015;5(1):1-12. doi.org/10.1016/j.ejfs.2013.04.002