1. Arthropod borne infectious disease

2. Arthropods that Transmit Disease
Ticks, mosquitoes, fleas and biting flies
Transmission usually by biting or ingestion
Sand flies are biting flies
Ingestion is usually how you will get some parasites

3. Infections Bacterial Viral (arboviruses) Parasites
Ricketsia ricketsii, Borrelia burgdorferi, Yersinia pestis, Francisella tularensis
Viral (arboviruses)
Dengue, West Nile, Encephalitic viruses
Parasites
Malaria, Dracunculiasis, tape worms
Arboviruses means arthropod borne viruses
Togaviridae, flaviviridae, bunyaviridae
Most parasites are by ingestion

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

5. Attachment, phagocytosis and breakdown of phagocytic membrane

6. Fever, nausea, severe headaches, muscle pain and rash
Characteristic rash is best diagnosis. Petichial (spotty from broken cappilary)

7. Rocky Mt. spotted fever
Not actually located in the rocky’s. Most common ricketsial disease.

8. Lyme Disease Borrelia burgdorferi Spirochete
Obligate 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 out

9. Borrelia burgdorferi 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)
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 “evolving”

10. 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

11. Lyme disease

12. Lyme disease

13. Only feeds 3 times in life. Lives about 2 years
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.

14. Compare to life cycle

16. Male/female adults, nymph, then larva

17. So 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.
Deer tick eating

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

19. Lyme disease rash

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

21. 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
All of these problems are due dissemination of bacteria to these sites. Loves your brain, heart, joints

22. 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
Maybe talk about the late stages of syphilus. Similar. Similar types of bugs.

23. Transmission Bacteria normally live in gut epithelium of tick
Must migrate to salivary glands to be secreted to host
Draw 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 don’t see them and they are there for multiple days.

24. 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
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 adjuvant
Also cell density, exposure to other stumuli are important too
How does it confer resistance if it is not expressed in the HOST???

25. How the vaccine works
Bacterial 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.

26. West Nile +RNA Flavivirus
transmitted by mosquitoes that usually infects birds
Many human infections are avirulent
infect humans, horses, dogs, cats, bats, chipmunks, skunks,squirrels, and domestic rabbits
In the western hemisphere mostly robins and crows, the virus amplifies, transmits to other mosquitoes, and transmits to more birds and so on
However this does not happen in mammals, so is a “dead end”

27. West Nile Severity 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 it
No vaccine for humans, but there is for horses.
Say the best prevention is by avoiding getting bit

28. Found in Africa, Europe, Middle East and Asia
Recent outbreaks in eastern europe and USA
Outbreaks in mid 2000’s had cases with 4-5% fatality rate. now few hundred cases with 2-20 fatalities.
Lots of media attention, afraid would become a large problem

29. Yersinia pestis Plague Transmitted by fleas Bubonic Pneumonic
Septicemic
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.

30. The disease normally replicates within rodent populations
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 animal

31. Plague Symptoms: Mostly general pain, fever, malaise, headaches Bubos
Bubos present in the bubonic form, which is an infection of the lymph nodes.
Prolirates inside bubos, then can disseminate to multiple organs
After 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.

32. 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

33. Francisella tularensis
Facultative intracellular pathogen causing tularemia or “rabbit fever”
Often 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.

34. Tularemia All 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.