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Arthropod borne infectious diseaseArthropods that Transmit DiseaseTicks, mosquitoes, fleas and biting fliesTransmission usually by biting or ingestion

Sand flies are biting fliesIngestion is usually how you will get some parasites2InfectionsBacterialRicketsia ricketsii, Borrelia burgdorferi, Yersinia pestis, Francisella tularensis

Viral (arboviruses)Dengue, West Nile, Encephalitic viruses

ParasitesMalaria, Dracunculiasis, tape wormsArboviruses means arthropod borne virusesTogaviridae, flaviviridae, bunyaviridaeMost parasites are by ingestion3Rocky Mountain Spotted FeverCaused by obligate intracellular bacterium Rickettsia rickettsiiTick borne disease

Explain obligate intracellular4

Attachment, phagocytosis and breakdown of phagocytic membrane5Fever, nausea, severe headaches, muscle pain and rash

Characteristic rash is best diagnosis. Petichial (spotty from broken cappilary)6

Rocky Mt. spotted feverNot actually located in the rockys. Most common ricketsial disease. 7Lyme DiseaseBorrelia burgdorferiSpirocheteObligate Intracellular pathogen

Talk about internal flagellum to move, corkscrew shape to actually move. Important for dissemination through tissues, can screw through your tissues and move out8Borrelia burgdorferi1.5MbpStrange genomic layoutLinear 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)Talk about obligate intracellular bacterium have small genomes due to decay. Say that decay is the loss of genes because they are not needed. Characteristics of genome decay are many pseudogenes buildup of nonsense and mutations, deletions, partial deletions, duplications, general mistakes that add up and eventually get deleted. Generally lose biosynth pathways, keep your uptake pathways, maybe have more. Less to maintain, less for the host to identify, less energy required to live. Genome is constantly changing and evolving9EpidemiologyTransmitted by ticks (mainly deer ticks)Most often by nymphal ticks

Mammalian reservoirs: mice and deer

Prevalent in northeast and midwest but spreading and increasing occurrence10Lyme disease

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Lyme disease12

Only feeds 3 times in life. Lives about 2 years. Transovarial transmission is rare, so they must pick it up as a larva or nymph on infected animal and bite you as a nymph or adult to transmit. Notice the summer feeding for the nymphs and fall for adults. Larva too small to feed on humans, nymphs can but adults are easiest. There is little to no transovarial transmission in these ticks.

13Compare to life cycle

Male/female adults, nymph, then larva16

Deer tick eating17So tiny. Talk about when ticks feed they give off nasty saliva cocktail that prevents coagulation and inflammation, so cant feel pain. Preventing inflammation will prevent immune cells from coming, therefore helps allow the bacteria to colonize the host. Will talk about the transmission later.Lyme disease symptoms1st 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!

Outwardly expanding red, the center outside stays red then the center clears. Treatment is harder later. Antibiotics for 2-4 weeks doxycycline.18

Lyme disease rash19

Explain how this happens. Bacteria corkscrew outward and get inflammation. However the spot in the middle clears so bullseye rash that is expanding outward20Lyme disease symptoms2nd 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

All of these problems are due dissemination of bacteria to these sites. Loves your brain, heart, joints21Lyme disease symptoms3rd 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 damageMaybe talk about the late stages of syphilus. Similar. Similar types of bugs.22TransmissionBacteria normally live in gut epithelium of tick

Must migrate to salivary glands to be secreted to hostDraw picture of tick. Say blood flows into gut, not back out! This temperature change (and probably others) cause the shift from moving from the gut epithelium to move to the hemolymph, then to salivary glands. While feeding the tick secretes all these nasty chemicals to prevent inflammation, coagulation, prevent pain, etc. so the bacterium get secreted into the host. This takes time, about a day to happen. That is why you are told to look for ticks on yourself and if you find them early, you can prevent lyme disease even if you are bit from an infected tick. Also a reason why nymphs transmit the most, they are small and really hard to see on you, so you dont see them and they are there for multiple days.23Vaccine LYMErixRecombinant Outer surface protien A (OspA) Your body doesnt 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

Vaccine recalled after a few years due to autoimmune problems with arthritis lawsuit, bad publicity. Made by GlaxoSmithKline. Ambiguous results for causing arthritis.with aluminum hydroxide as an adjuvantAlso cell density, exposure to other stumuli are important tooHow does it confer resistance if it is not expressed in the HOST???

24How the vaccine worksBacterial migration from midgut 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

Say that bacterial migration is blocked. Draw on board. Cant get to salivary glands, so cant get into host.25West Nile+RNA Flavivirus transmitted by mosquitoes that usually infects birdsMany human infections are avirulent

infecthumans,horses,dogs,cats,bats,chipmunks,skunks,squirrels, and domesticrabbits

In the western hemisphere mostly robins and crows, the virus amplifies, transmits to other mosquitoes, and transmits to more birds and so onHowever this does not happen in mammals, so is a dead end26West NileSeverity of infections:Avirulent

Mild fever (West Nile Fever)

Serious meningitis or encephalitis

West nile Fever-general malaise, nausea, fever. Could have gotten west nile and not known itNo vaccine for humans, but there is for horses.Say the best prevention is by avoiding getting bit27

Found in Africa, Europe, Middle East and AsiaRecent outbreaks in eastern europe and USAOutbreaks in mid 2000s had 2000-5000 cases with 4-5% fatality rate. now few hundred cases with 2-20 fatalities. Lots of media attention, afraid would become a large problem28Yersinia pestisPlagueBubonicPneumonicSepticemic

Transmitted by fleas

Plague is still around, even in the US. This sign is from last year in Colarado warning people to NOT have contact with the prarie dogs.Bubonic, infection of the lymph nodes.Pneumonic, lung infection. Aerisols. Huge problem as a bioterrism weapon. Category A select agent due to high fatality rate, severity of pneumonic infections (the favorite of any bioterrorist)Septicimic- bad news. Dissemiation in blood. You are going to die soon.29

The disease normally replicates within rodent populations. Can then leak into other mammalian populations and cause fatal disease.Transmission to animals from fleas:Normally lives in esophagus and digestive tract of fleas. To get transmitted, it creates a biofilm in the esophagus, blocking it. When the flea then takes in blood, cannot go down, so is regugitated with chunks of biofilm thus infecting animal30PlagueSymptoms: Mostly generalpain, fever, malaise, headachesBubos

Bubos present in the bubonic form, which is an infection of the lymph nodes.Prolirates inside bubos, then can disseminate to multiple organsAfter dissemination, can lead to septicemia leading to multiple organ failure, gangrene, disseminated intravascular coagulation (talk out the words. This is lots of clotting in your blood vessles, stops up all your clotting protein, you bleed everwhere and have tissue death)Untreated bubonic is about 50% fatal. Untreated septicemic and pneumonic plague, almost always fatal.31Molecular mechanismsPlasmids 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

Francisella tularensisFacultative intracellular pathogen causing tularemia or rabbit feverOften by ticks, also from mosquitoes and biting flies

Define facultative intracellular. Most often by ticks, naturally. Nice blister. Leads to dissemination. Lungs, spleen and liver hit hard. Death eventually by liver failure?? Not sure yet.33TularemiaAll feasible routes of infection

Infects >250 species animals

Infects all cell types tested

Pneumonic infection is most severe. Also easiest for bioterrorism. Infects amoebae, ticks, birds, fish, humans, etc. all cell types too. However it loves living in all your phagocytic immune cells.34