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Arthropod borne infectious disease

Arthropod borne infectious disease. Arthropods that Transmit Disease. Ticks, mosquitoes, fleas and biting flies Transmission usually by biting or ingestion. Infections. Bacterial Ricketsia ricketsii , Borrelia burgdorferi , Yersinia pestis , Francisella tularensis Viral ( arboviruses )

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Arthropod borne infectious disease

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  1. Arthropod borne infectious disease

  2. Arthropods that Transmit Disease • Ticks, mosquitoes, fleas and biting flies • Transmission usually by biting or ingestion

  3. Infections • Bacterial • Ricketsiaricketsii, Borreliaburgdorferi, Yersinia pestis, Francisellatularensis • Viral (arboviruses) • Dengue, West Nile, Encephalitic viruses • Parasites • Malaria, Dracunculiasis, tape worms

  4. Rocky Mountain Spotted Fever • Caused by obligate intracellular bacterium Rickettsia rickettsii • Tick borne disease

  5. Fever, nausea, severe headaches, muscle pain and rash

  6. Rocky Mt. spotted fever

  7. Lyme Disease • Borreliaburgdorferi • Spirochete • Obligate Intracellular pathogen

  8. Borreliaburgdorferi • 1.5Mbp • Strange genomic layout • Linear chromosome (900 kb) • Has over 20 circular AND linear plasmids • Genome decay in obligate intracellular bacteria • Loses many biosynthesis pathways (why make it if you can get it from the host)

  9. Epidemiology • Transmitted by ticks (mainly deer ticks) • Most often by nymphal ticks • Mammalian reservoirs: mice and deer • Prevalent in northeast and midwest but spreading and increasing occurrence

  10. Lyme disease

  11. Lyme disease

  12. Compare to life cycle

  13. Deer tick eating

  14. Lyme disease symptoms 1st stage: first few days erythema migrans (outwardly expanding rash) Therefore gets a bullseye appearance. Not always occurs (most of the time though) Flu-like symptoms too (fever, headache, muscle soreness, malaise) Best treatable stage!

  15. Lyme disease rash

  16. Lyme disease symptoms • 2nd stage: Dissemination: days to weeks • spreads to bloodstream and may have bullseye rash appear at other sites of the body • Also pain in muscles joints and tendons, heart palpitations, strong headaches

  17. Lyme disease symptoms • 3rd Stage: Persistent infections (months later) • Brain, nerves, eyes, heart, joints • Cognitive impairment, weakness, pain in joints (especially the knees), fatigue • Can end up with permanent damage

  18. Transmission • Bacteria normally live in gut epithelium of tick • Must migrate to salivary glands to be secreted to host

  19. Vaccine LYMErix • Recombinant Outer surface protien A (OspA) • Your body doesn’t make antibodies to OspA normally • OspA only expressed in unfed ticks, not in fed ticks or host • Temperature is the trigger to stop OspA and start making OspC • other triggers for making virulence proteins are pH and Fe starvation

  20. How the vaccine works • Bacterial migration frommidgut to salivary glands is inhibited when ticks feed on OspA (and also in OspC) immunized mice • So immune serum appears to kill the bugs in the tick or prevent migration

  21. West Nile • +RNA Flavivirus • transmitted by mosquitoes that usually infects birds • Many human infections are avirulent

  22. West Nile Severity of infections: • Avirulent • Mild fever (West Nile Fever) • Serious meningitis or encephalitis

  23. Yersinia pestis • Plague • Bubonic • Pneumonic • Septicemic • Transmitted by fleas

  24. Plague • Symptoms: Mostly general • pain, fever, malaise, headaches • Bubos

  25. Molecular mechanisms • Plasmids and pathogenicity island • Specialized Type 3 Secretion system • Yop (Yersinia outer proteins) for evading immune system This includes preventing phagocytosis, adhesion, and inducing macrophage death

  26. Francisellatularensis • Facultative intracellular pathogen causing tularemia or “rabbit fever” • Often by ticks, also from mosquitoes and biting flies

  27. Tularemia • All feasible routes of infection • Infects >250 species animals • Infects all cell types tested

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