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Medical/ forensic entomology

Medical/ forensic entomology. Lecture 23. Insects are medically important. Create nuisance and phobia Cause wounds Inject venoms Cause allergies Transmit diseases (vectors) Forensically useful. Some just don’t like insects. Some insects are true nuisance.

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Medical/ forensic entomology

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  1. Medical/forensic entomology Lecture 23

  2. Insects are medically important • Create nuisance and phobia • Cause wounds • Inject venoms • Cause allergies • Transmit diseases (vectors) • Forensically useful

  3. Some just don’t like insects

  4. Some insects are true nuisance Bush flies (Diptera: Muscidae) in Australia occur in high density Eye Gnats (Diptera: Chloropidae) infestation hurts organic farming in California

  5. Bed bugs resurge • Bed bugs (Hemiptera: Cimicidae) (video)

  6. Some suffer from imaginary pests • Entomophobia: an admitted, exaggerated, illogical, and unexplained fear of insects • Contagious hysteria: imaginary pest infestation that upset a group of people at the same time (due to crowded conditions, stress, changing climates, etc) • Delusory parasitosis: individual case of delusion of parasitism, insect bites

  7. Venoms • Defense mechanism of social hymenopterans (bees, wasps, ants) • Some people are hypersensitive to venoms and can have a serious or fatal reaction

  8. Reaction to venom • Inflammatory response • Hypersensitivity (anaphylaxis) • Most fatalities caused by honey bees

  9. Blister • Some insect toxins can cause injury • Blister beetles (Meloidae) contain cantharidins, which cause blistering of the skin • Some rove beetles (Staphylinidae) contain toxic paederin, which can cause dermatitis

  10. Insects as causes and vectors of disease • Insects can transmit protists, viruses, bacteria and nematodes • Mosquito-borne • St. Louis encephalitis, Equine encephalitis, West Nile virus, Dengue, Yellow fever, Malaria, Dog heartworm, Filariasis • Louse-borne • Epidemic typhus • Flea-borne • Plague, Murine typhus • True bug-borne • Trypanosoma

  11. Malaria • 120 million new cases each year • Pathogen: Parasitic protist, Plasmodium • Vector: Anopheles mosquito • Host: Human • Complex life cycle

  12. Yellow Fever • Pathogen: flavivirus (single-stranded RNA virus) • Vector: Aedesaegyptiand others • Three distinct cycles of transmission • Urban cycle (reservoir: humans; vector: A. aegypti) • Sylvan cycle (reservoir: non-human primates; vector: Haemagogusand A. africanus) • Intermediate cycle (reservoir: humans and non-human primates; vector: Aedessp.)

  13. Plague • Caused by the enterobacteriaYersiniapestis • Carried by rodents and rats • Vectored by fleas (Xenopsyllacheopis) • Bubonic plague: likely cause of Black Death • Symptom: an infection of the lymph glands, which become swollen and painful • Acral gangrene (fingers, toes, lips, nose)

  14. Forensic entomology • Application of insect biology to criminal matters • Based on a principle of ecological succession in a corpse following death • Diptera, Coleoptera, Lepidoptera, and various mites

  15. Estimating the Postmortem interval (PMI) • Setting a minimal and maximal probable time interval between death and corpse discovery • Affected by weather, ambient temperature, place • Usually based on early wave successors (blow flies and flesh flies) and their developmental stages • Some insects can be informative for understanding antemortem circumstances • Abuse and rape • Bites and stings • Absence of insects Video 1, Video 2

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