MEDICAL ENTOMOLOGY. Medical Entomology. Medical Entomology is a division of biology, that focuses on the study of medically important insects Other arthropods often get thrown into the discipline – such as spiders, scorpions, mites and ticks. Insects. >1,000,000 species: ¾ of animals
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Medical Entomology • MedicalEntomology is a division of biology, that focuses on the study of medically important insects • Other arthropods often get thrown into the discipline – such as spiders, scorpions, mites and ticks
Insects • >1,000,000 species: ¾ of animals • Mostly beneficial or harmless • Pollination (most fruit and vegetable crops) • Food for birds and fishes • Produce honey, wax, shellac, silk • Biological control (insect & weeds) • Scavengers: feed on dead plant and animal
Insects • Help in genetics, toxicology, behavior, pharmacology, physiology, etc • Forensic Entomology • Medical Treatment (honey & venom of honeybee, Cantaridin, maggothrapy, ..)
Cantaridin • Cantharidinis a chemical derived from the green blister beetle (Spanish fly;Lytta vesicatoria) (Meloidae: Coleoptera). • Cantharidin is a wart removal compound • Despite the toxicity of cantaridin, people have historically used Spanish fly to boost sexual function but it's sometimes resulted in adverse
Apitherapy The medical use of any honey bee Product including, honey, pollen, Royal jelly and bee venom Bee venom can be support a healthy immune system, multiple scelerosis, arthritis, depression and more Albert Einstein stated that “without honey bees, the world would cease to exist within 4 years”. Allergic. Some people can DIE from a bee sting
Maggot Therapy Lucilla sericata (Dip. Calliphoridae) Introduction of live, disinfected maggots (fly larvae) into the non-healing skin and soft tissue wound(s) for cleaning out the necrotic (dead) tissue within a wound (debridement) and disinfection. Beneficial effects of maggots on a wound: debridement, disinfection and enhanced healing. Debridement is selective or not? Maggots secret gamma-interferon and interleukin (IL-8, IL-10, and fibroblast growth factor beta-FGF) resulted in wound healing
Maggot Therapy • Maggots secret a broad spectrum of proteolytic enzymes that liquefy necrotic tissue, and then absorb the semi-liquid result within a few days. • Secretions believed to have broad-spectrum antimicrobial activity include • Allantoin and Urea: wound pH , alkaline conditions unfavorable to many bacterial species • phenylacetic acid, phenylacetaldehyde are secreted by midgut bacteria • (Proteus mirabilis) are anti-microbes • proteolytic enzymes • Bacteria not killed by these secretions are subsequently ingested and lysed within the maggots.
Negative Impacts of Insects • Less than 3% are pests • Destroy food crops(5-50%) In Iran: food of 7-10 Millions • Attack humans and pets • Transmit diseases
Negative Impacts of Insects : • Annoyance, injury and death to humans and animals • mosquitoes, lice, fleas etc annoy and discomfort • Venomous insects can even cause death • Vector disease – e.g. malaria, yellow fever, encephalitis, Lyme disease • Parasites of domestic animals e.g.. stable fly, horn fly, screwworm
Negative Impacts of Insects: • Injure crops, forests and ornamentals • direct • Indirect - vectors of plant pathogens e.g. viruses, fungi, bacteria
Negative Impacts of Insects: • Destruction or damage to stored products or possessions • Insects feed on stored grains and processed foods • Feed on household possessions: clothes moths and carpet beetles • Termites cause serious damage to homes
Arthropod Classification Kingdom: Animalia Group: Invertebrate Phylum: Arthropoda Subphylum: Trilobita Chelicerata Antennata
Chelicerata; Class Arachnida: • spiders, mites, ticks, sun-scorpions and scorpions • Mostly terrestrial arthropods • Body: cephalothorax + abdomen • No wing • Chelicerae but lack antennae • Have 4 pairs of leg • Have a pedipalp
ChelicerataClass: Arachnida Order: Scorpionida All may produce painful stings and the stings of one species (Hemiscorpiuslepturus) may be fatal, particularly to small children and older persons.
ChelicerataClass: ArachnidaOrder: Sulpugida Camel spiders, wind scorpions, sun spiders or solifuges. The order includes more than 1,000 described species in about 153 genera. No potential danger to humans.
ChelicerataClass: ArachnidaOrder: Araneida: Spiders • Body: The cephalothorax and abdomen, 8 legs, chelicerae with fangs that inject venom. • At least 43,678 spider species, • All known species are predators, mostly preying on insects and on other spiders. • Black widow, Latrodectus in the family Theridiidae, contains 32 recognized species. Its bite is dangerous because of the neurotoxin latrotoxin. • Latrodectus bites rarely kill humans if proper medical treatment is provided.
Chelicerata: Class: ArachnidaOrder: Acarina Chelicerata; Class Arachnida: • Contains mites and ticks. Over 50,000 species, >a million species. • Damage to crops (mites) • Some are parasit of humans and other mammals, • Some are vectors of diseases such as CCHF, Scrub typhus, Rickettsialpox, Lyme disease, Q fever, Colorado tick fever, Tularemia, Tick-borne relapsing fever, Babesiosis, Ehrlichiosis and Tick-borne meningoencephalitis. • Allergen and the stimulation of asthma in people
Class: Insecta: : • 1)Apterygota 2)Pterygota • The most medically important Orders: • Blataria • Siphonaptera • Diptera • Anopolura • Hemiptera
Medical Importance of Arthropods (Insects) • Direct effects: Myiasis • Blue-bottle, Flesh flies, Green-bottles, • Lucilia spp, Sarcophaga spp., Calliphora spp. َAllergy • House dust mite, Cockroaches, venom of insects Dermal disease • Sarcoptes scabei : “Scaly leg; Sarcoptic mange” • Paederus fuscipes; Lytta vesicatoria : “Dermatitis Linear” Bloodless • Cimex lectularis • Hard ticks • Auchmeromyia luteola, The Congo floor maggot
Myiasis • First time Hope (1984) used for larvae on human • In Greece “Myia” means fly • Myiasis is important in Health, Medicine, Veterinary, and Criminal aspects
Medical Importance of Arthropods (Insects) • Direct effects: Dermal disease burrows into the dead layer of skin
Medical Importance of Arthropods Indirect effects: Vector of pathogens: Mechanical Transmission • No alteration and No propagation House flies, Cockroaches Biological Transmission 1-Only propagation in insect body: Plaque in fleas 2- Only morphological alteration and movement in insect body: Onchocerciasis or River Blindness caused by Onchocerca volvulus transmitted by Simulium spp. 3- Propagation and alteration: Plasmodium spp in Anopheles spp Leishmania spp in sand flies 4- Transovarian transmission Viruses in Ticks Wolbachia in insects
Factors That Determine Insect Vectors Role in Disease Transmission • Ecological niche (s) mosquito species occupies • (Urban/rural, Indoor/outdoor, …) • Relationship to man or domestic animal(s) • Longevity • Pathogen susceptibility
Insect Classification : • Kingdom: Animalia • Phylum: Arthropoda • Subphylum: Antennata • Class: Crustacea • Class: Diplopoda • Class: Chilopoda • Class: Symphyla • Class: Insecta (Hexapoda)
Diplopoda • Two pairs of legs per segment (1st with no appendages at all, and the next few which only have one pair of legs). • Common species have between 36 and 400 legs; maximum 750 legs • Many species also emit poisonous liquid secretions or hydrogen cyanide gas • This chemical brew is fairly harmless, usually causing only minor effects on the skin, the main effect being discoloration, but also pain, itching, local erythema, edema, blisters, eczema, and occasionally cracked skin. Eye exposures to these secretions causes general eye irritation and potentially more severe effects such as conjunctivitis and keratitis.
Chilopoda (Centipedes) • One pair of legs per body segment. Varying number of legs from under 20 to over 300. • Centipedes have an odd number of pairs of legs, e.g. 15 or 17 pairs of legs (30 or 34 legs) but never 16 pairs (32 legs) • A pair of venom claws or forcipules formed from a modified first appendage. • Size can range from a few mm to about 30 cm (12 in) • Apprx 8,000 species, 3,000 have been described. • Some species of centipede can be hazardous to humans • Bite to an adult human is usually very painful and may cause severe swelling, chills, fever, and weakness, but unlikely to be fatal. • Bites can be dangerous to small children and those with allergies to bee stings and can induce anaphylactic shock in such people.
The Insect Body • Primitive insects were wormlike with many segments – up to 20 • Today's insects have reduction in number and fusing of segments to form head, thorax and abdomen • Head – several segments fused • Thorax - 3 segments • Abdomen – usually 6 to 10 segments
Thorax Abdomen Spiracles = breathing Insect External Morphology
Insects On the head : one pair of antennae, a pair of compound eyes, and several sets of simple eyes
Types of Mouthparts • Chewing mouthparts: • Beetles, crickets, ants • Piercing- sucking Mouthparts: – aphids, bugs, mosquitoes, mites/ticks* * not insect
Mouthparts of primitive insects were adapted for chewing; consist of a pair of mandibles, and two pairs of maxillae • Throughout evolution other types of mouthparts such sucking mouthpart have evolved:
Antennae & Chewing Mouthpart: Japanese Beetle Chewing mandibles
Antennae & Chewing Mouthpart: Billbug Weevil Snout & Chewing mandibles Antenna
Antennae & Sucking Mouthpart:Bug Antenna Scutellum Piercing proboscis
Antennae & Siphoning Mouthpart: Antenna Siphoning proboscis
The thorax is composed of 3 segments and each one has a pair of legs; the last two have a pair of wings. • Each leg is usually divided into 5 segments; the segments include basal segment or coxa, trochanter, femur, tibia, and tarsus
The exoskeleton (Inside out) • Serves to give rigid structure, protect internal organs, attachment point for muscles, and prevent water loss (desiccation) • Most of the exoskeleton is hardened or sclerotized in plates called sclerites • In between sclerites the body wall is softer – allows for growth, expansion and movement
The Body Wall • The body wall or integument is composed of a layer of cells called the epidermis, with the basementmembrane on the inside and the cuticle on the outside
The body wall (cont’d) • The epicuticle (top layer) is important in preventing water loss • The exocuticle gives the cuticle its strength and flexibility and is formed from chitin (also base for wood, hair, horns)