Infectious Diseases

  • Bacteria

  • Viruses

  • Fungi

  • Prions

  • Amoeba

Meningitis

  • Fairly common infection of the meninges

  • Bacterial meningitis

    • High fever, sudden headache, stiff neck —- nausea, seizures, coma, death

    • In US 60% caused by Streptococcus pneumonia (pneumococcus)

    • 35% Neisseria meningitides (meningococcus)

  • Viral Meningitis- 10x more common than bacterial

    • Enterviruses (from intestines), West Nile Virus (mosquitoes), arboviruses (ticks and spider), herpes (rarely)

    • Same symptoms as bacterial

    • Antibiotics dont help

    • Most people recover

  • Fungal Meningitis

    • Usually in immunocompromised people

    • Slower developing infection- high mortality

Botulism

  • 1882 Sausage poisoning

  • Rare now- 10 cases per year in the us

    • But, 80-100 cases per year in infants

  • Caused by neurotoxin released by a bacteria

    • One of the most toxic substances known

    • 7 different types (A-G) (A is in Colorado)

  • Food poisoning —- flaccid paralysis

  • Usually get toxin from food, but wound is possible, bacteria in gut

    • 20% of children that get it, get it from spores in honey

How does Botulinum toxin work?

  • Prevents release of acetylcholine

Botulinum Toxin Symptoms

  • Blocks acetylcholine release at NMJ and in nervous system

  • Facial and throat muscles are first paralyzed (because we use them a lot)

  • Dry mouth, blurred vision, double vision, dilated pupils

    • Then, drooping eyelids, hoarse voice, difficulty speaking, difficulty understanding language

  • Paralysis descends the trunk- respiratory muscles and diaphragm

  • Death due to respiratory failure

  • In infants

    • Apathy, weakened crying, loss of appetite, constipatation, floppy baby syndrome

Botulinum Toxin treatments

  • Antitoxins

Tetanus Toxin

  • Bacterial Toxin

  • Works a lot like botulinum toxin, except…

    • Travel retrograde to dendrites

    • Crosses synapse to prevent release of GABA

      • One cell up

  • Causes overactivity of motor neurons- constant contraction, paralysis

  • Vaccine works- very rare in developed countries

  • Treated with antitoxin

Neurosyphilis

  • Bacterial infection leading to meningitis

  • Headache, nausea, vomiting, seizures — due to inflammation of meninges

    • If left untreated - pain, lack of proprioception, pee (polyuria) (always feel like they have to pee), cognitive impairments

  • Syphilis is an STI

    • Chancres (sores on genitals) - within 3§ hours

    • 2-6 weeks infection spreads throughout body

    • Latent stage - no symptoms - for up to 15 years

    • Third stage: 10% will develop neurosyphilis

  • Easily treated with antibiotics

    • For neurosyphilis, need high does - daily infusion for 10-14 days

The Tuskegee Studies

  • 1932-1972

  • Designed to study the course and spread of syphilis

  • 600 individuals in rural alabama

    • Poor, sharecroppers, black, male

    • 400 already infected, 200 not

  • 1945 penicillin found to effectively treat syphilis

    • but not given to the Tuskegee participant

  • 1972 news stories described study- public outrage

    • Class action law suit

  • Led to concept of informed consent

Poliomyelitis (Polio)

  • Polio virus

  • 1% of infected people develop polio

  • Infects and kills motor neurons

    • Primarily of lower extremities

  • Vaccines have pretty much eliminated polio in the developed world

Rabies

  • Viral infection

  • Enters body through a bite

  • 80% becomes aggressive, combative, hallucinations

  • 20% get flaccid paralysis

  • Fatal - die within days of showing symptoms

    • Vaccinations make it rare in humans in US

  • You don’t get symptoms immediately when you get bite, it remains latent for a bit, time for treatment (rabies vaccination)

Prions

  • Scrapie - sheep and goats

  • Mad cow disease

Brain-eating amoeba

  • N. Fowleri - common amoeba in warm, freshwater lakes

    • Causes primary amoebic meningoencephalitis (PAM)

  • Very rare but 100% lethal

    • 3 Survivors in US 9 worldwide

  • Symptoms look like meningitis