Host defenses pt 2

two examples of acid fast bacterial infections

• leprosy

• tuberculosis

Hansen’s disease (Leprosy)

• etiologic agent

Mycobacterium leprae

• acid-fast bacterium (waxy cell wall)

• intracellular infection (macrophages)

• grows very slowly

• generation time: 14 days

two forms of leprosy

1. tuberculoid

   • loss of sensation

2. lepromatous

   • granulomas

leprosy: tuberculoid

• loss of sensation

• affects skin pigment

• nerve damage

incubation period for tuberculoid

2-5 years

leprosy: lepromatous

• granulomas

• due to cellular defenses of macrophages “wall off”

• what we think of when someone says “leprosy”

incubation period of lepromatous

9-12 years

leprosy diagnosis

skin scraping or biopsy

• acid-fast stain

• won’t grow in a lab

leprosy treatment

long-term antibiotics

• 6-12 months

• multi-drug therapy (MDT)

• offered free in endemic countries

• no vaccine

• drug resistance isn’t a problem

leprosy colonies

• not very contagious

• no longer infectious after 1 month of antibiotics

• excluded based on social stigma

tuberculosis etiological agent

Mycobacterium tuberculosis

• acid-fast bacterial infection

• ancient disease

• “consumption”

• “white plague”

tuberculosis progression

infection —90%—> latent —10%—> active

can you survive tuberculosis is treated?

yes

what happens if you never receive treatment for tuberculosis?

death

• 70% die in 10 years

• faster if HIV+