Infectious Diseases of the Cardiovascular and Lymphatic

Systems

The Cardiovascular System

• Heart• Blood vessels• Lymphatics• Lymph nodes, spleen,

MALT• RBC• WBC: macrophage-

monocytes, T and B lymphocytes

The Blood

• Carries O2, CO2, nutrients

• Cells + plasma• Septicemia – growth

of bacteria in blood• Septic shock –

endotoxin (LPS) release macrophage cytokines low blood pressure, high fever

Cardiovascular System Defenses

• Defensins - antimicrobial proteins

• Phagocytes, antibodies, complement

• Filtering function of Lymph Nodes

• No normal flora

• Transient flora may contribute to disease

• Infections in blood are systemic

Previous Microbes of the Day That Infect the Cardiovascular System

• Eukaryotes– Plasmodium falciparum (malaria)

• Principles of Infectious Disease– Bacillus anthracis (anthrax)

• Clinical Immunology– Rheumatic Fever following

Streptococcus pyogenes infection = Type II Hypersensitivity

Yersinia pestis

• Cause of Plague• Gram negative rod• Grows in digestive

tract of flea = vector• Reservoir is rodents,

prairie dogs• Endemic above

4,000 ft elevation in Arizona

Plague in Arizona

Prairie Dog Plague, Flagstaff, 2001

• 99 colonies observed

• 49 colonies experienced >99% mortality May-September 2001

• Y. pestis confirmed as cause of die offs at 19 colonies

Bubonic Plague

• Transmitted by flea bite

• Y. pestis enters blood and grows in macrophages in lymph nodes

• Swollen lymph nodes are buboes

Plague

• Septicemic plague

– proliferation in blood

– endotoxin shock

• Pneumonic plague

– lung infection

–100% mortality

– spread by droplets

• Curable with antibiotics if diagnosed quickly

Lyme Disease• Primary Lesion

– bulls-eye rash on skin

• Secondary lesion– flu-like symptoms,

neurological symptoms

• Tertiary lesion– inflammation of

large joints

Lyme Arthritis

• Immune system Type III hypersensitivity to persisting antigen antigen-antibody complexes inflammation, tissue damage by neutrophils

Borrelia burgdorferi

• Spirochetes are very narrow spiral-shaped bacteria

• Gram negative

• Motile

Lyme Disease Vectors

• Tick vector bites infected reservoir (deer, mouse) and become infected; transmit disease to humans through bites

Disease emerged when humans moved into tick/reservoir environment

Rocky Mountain Spotted Fever

• Fever, chills, headache, muscle pain

• Red --> black rash

• Transmitted to humans by tick bites

Rickettsia rickettsii

• Gram negative bacillus or coccobacillus

• Transmitted to humans by tick bites

Vectors: Wood Tick and Dog Tick

RMSF Epidemiology

1942-2002

Rickettsia• Bind to cell

surface and are taken in by phagocytosis

• Escape from phagosome into cytoplasm

Rickettsia• Obligate

intracellular bacteria

• Polymerize cell actin for locomotion

• Have ETC

• Obtain nutrients and NAD+ and CoA from host

Rocky Mountain Spotted Fever

• Treatable with antibiotics

• Diagnosed using fluorescent antibodies on tissue samples, PCR

• 20% of untreated cases and 5-10% of treated cases are fatal