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Arthropods insects and arachnids which many times serve as vectors of transmission; Eukaryotic members of the microbial world; Vectors of transmission transmit a disease from host to host Mechanical vector (of transmission by Arthropods) transfer pathogen from one surface to another Biological vector (of transmission by Arthropods) movement between hosts is an essential part of pathogen life cycle (cannot complete life cycle without intermediate host); i.e. Plasmodium (causes malaria) in Anopheles mosquito; Trypanosomes (cause Sleeping sickness) in tsetse fly Anopheles mosquito Biological vector of Plasmodium (causes malaria) tsetse fly Biological vector of Trypanosomes (cause Sleeping sickness) reservoir Animals may also act as (i.e. rats & bubonic plague) Incidence of arthropod diseases can be decreased by controlling vectors or hosts, i.e. plague in US controlled by mostly eliminating rat populations carrying Yersinia pestis; spraying for mosquitoes to decrease west nile virus in MO Mosquitoes Arthropods which insert feeding tube through host's skin, Ingest blood; can pick up infectious agents, (i.e. west nile virus), transfer to subsequent hosts diseases transmitted by mosquitoes: Malaria, yellow fever, dengue fever, West Nile encephalitis Fleas wingless insects (Arthropods), can jump up to 30cm; Usually just a nuisance but can transmit some pathogens, i.e.Yersinia pestis; can live in vacant buildings, dormant for months; Mature quickly and jump to greet new hosts Yersinia pestis Causitive agent of plague; most common pathogen transmitted by Fleas 1. Fleas pick up agent when biting an infected host 2. bacterium multiplies inside flea, blocks digestive tract of flea 3. Causes flea to bite constantly, trying to feed 4. Starving fleas bite repeatedly, passing bacteria to (new) host Lice small, wingless insects (Arthropods); suck blood through the skin; have appendages adapted for attachment Pediculus humanus Arthropod which easily spreads by direct contact or contact with personal items; Humans are the only host for this type of lice; Survives only a few days away from (human) hosts Body lice can transpmit bacterial diseases: -trench fever (Baronella quintana); -epidemic typhus (Rickettsia prowazekii); -relapsing fever (Borrelia recurrentis) Head lice do not transmit disease Ticks arachnids (Arthropods) which lack wings and antennae; have four pairs of legs; have fused thorax and abdomen; Live in low vegetation, wait for host to pass by; Burrow into skin with mouthparts; May go unnoticed for days; feeds continually Rickettsia rickettsii bacterium that causes Rocky Mountain spotted fever; transmitted by Dermacentor andersoni (aka Wood tick) Borrelia burgdorferi bacterium that causes Lyme disease; transmitted by Ixodes scapularis (a tick species) Saliva of some ticks can produce tick paralysis (muscle weakness) especially in children; recovery follows removal Mites are tiny, fast moving arachnids (Arthropods); Live on outer surface of plants, animals (i.e. chiggers); Large numbers often live indoors, feed on shed skin cells (i.e.dust mites) Demodex Microscopic mites that live unnoticed in hair follicles or oil producing glands Mites do not transmit diseases but can trigger asthma in those who are allergic to a protein found in their feces. chiggers mite larvae which may attach, feed on fluids within skin cells, cause intense itching Sarcoptes scabiei mite transmitted by personal contact, causes scabies