MICR 201 Microbiology for Health Related Sciences

1. Lecture 15: Microbial diseases of the cardiovascular and lymphatic system Edith Porter, M.D. MICR 201 Microbiology for Health Related Sciences

2. Lecture outline • Cardiovascular and lymphatic systems • Bacterial diseases • Sepsis and septic shock, infections of the heart, rheumatic fever, systemic diseases caused by bites and scratches, vector transmitted diseases • Viral diseases • Hemorrhagic fevers • Protozoan diseases • Malaria, Chagas disease • Helminthic diseases • Schistosomiasis

3. The Cardiovascular and lymphatic system (1) • Blood (plasma and formed elements)—Transports nutrients to and wastes from cells • Plasma leaves blood system to become interstitial fluid • Lymph capillaries—Transport interstitial fluid to blood • Lymph nodes—Contain macrophages, dendritic cells, B cells and T cells

4. The Cardiovascular and lymphatic system (2)

5. Sepsis and septic shock • Septicemia • Presence of bacteria in blood with severe symptoms • Sepsis • Bacteria present (and proliferating) in blood and dissemination into various with organ dysfunction • Induces a systemic inflammatory response syndrome • Severe sepsis • Sepsis + decreased blood pressure • Septic shock • Sepsis + low blood pressure cannot be controlled

6. Lymphangitis may accompany sepsis • Lymphangitis • Inflamed lymph vessels accompanying septicemia and septic shock

7. Sepsis • Gram-negative sepsis • Endotoxins(LPS) induces cytokine release by macrophages and subsequently causes blood pressure to decrease • Antibiotics can worsen condition by killing bacteria and liberating endotoxin • Gram-positive sepsis • Less often • Less severe • Lipoteichoic acids in the gram positive cell wall can also induce cytokine release and symptoms of sepsis but to a lesser degree • Mostly observed during nosocomial infections • Staphylococcus aureus • Enterococcusfaecium and E. faecalis • Puerperal spesis

8. Bacterial infections of the heart • Endocarditis • Inflammation of the endocardium • Subacute bacterial endocarditis • Alpha-hemolytic streptococci from mouth • Acute bacterial endocarditis • Staphylococcus aureus from mouth • Pericarditis • Streptococci

9. Bacterial infections of the heart: endocarditis

10. Consequences of endocarditis

11. Rheumatic Fever • Inflammation of heart valves and joints • Autoimmune complication of Streptococcus pyogenes infections

12. Brucellosis (undulant fever) • Brucella, gram-negative rods that grow in phagocytes • Granulomas form • If bacteria are not controlled they can reenter the bloodstream andcause recurrent • B. abortus (elk, bison, cows) • B. suis (swine) • B. melitensis (goats, sheep, camels) • Undulating fever that spikes to 40°C each evening • Transmitted via milk from infected animals or contact with infected animals

13. Selected diseases transmitted by scratches and bites • Bartonella henselae: cat-scratch disease • Pasteurella multocida: animal bites http://www.lib.uiowa.edu/hardin/md/pictures22/dermnet/cat_scratch_disease_8.jpg

14. Animal bites and scratches: Pasteurellamultocida • Normal microbiota of the upper respiratory tract of a number of animals • A frequent cause of opportunistic infections in domestic livestock • Usually acquired by humans from the bite or scratch of a dog or cat • Infection develops at the site of the wound and can spread via the lymphatics or via blood stream to a number of other organs • Virulent strains are encapsulated, but no other virulence factors are known • The organism is unusually sensitive to penicillin

15. Rickettsia infections • Epidemic typhus • Rickettsia prowazekii • Reservoir • Rodents • Vector • Lice (Pediculus humanus corporis) • Transmitted when louse feces is rubbed into bite wound • Rocky Mountain spotted fever • Rickettsia rickettsii • Measles-like rash except that the rash appears on palms and soles too • Vector • Ticks

16. Rocky Mountain Spotted Fever • Rickettsia are obligate intracellular parasites • Infect and grown in endothelial cells of the vascular system

17. Rocky Mountain Spotted Fever cases 1997 - 2002

18. Plague • Causative agent: Yersinia pestis, gram-negative rod • Reservoir • Rats, ground squirrels, prairie dogs • Vector • Fleas • Bubonic plague • Bacterial growth in blood and lymph • Septicemia plague • Septic shock • Pneumonic plague • Bacteria in the lungs • Necrotizing hemorrhagic pneumonia • Human to human transmission • Black Death in the middle ages

19. Boubonic plague and US plague cases between 1970 - 2004

20. Lyme Disease • Causative agent: Borrelia burgdorferi • Reservoir: Deer • Vector: Ticks

21. Clinical stages of Lyme disease • Acute: Bull's-eye rash, fever, muscular and joint pain, meningeal irritation • Chronic : Disabling arthritis, myocarditis, meiningoencephalitis

22. Lyme disease in the U.S., 2005

23. Viral hemorrhagic fever • Yellow fever • Liver cells are primary target • Dengue fever • 4 serotypes • Infection with a second serotype can lead to severe manifestation • Ebola virus • High mortality rate of 60 – 80% within a few days

24. Malaria • Caused by Plasmodium species: • P. vivax • P. ovale • P. malariae • P. falciparum • Vector: Anopheles mosquito • Definitive host: Anopheles mosquito

25. Malaria

26. Malaria in the United States

27. Malaria

28. Chagas’ Disease (1) • American trypanosomiasis • Causative agent Trypanosoma cruzi • Reservoir: Rodents, opossums, armadillos • Transmitted via feces of kissing bug • Infects organs, chronic infection, organ megaly

29. Chagas ‘Disease (2) • Endemic in Mexico, Central America, and South America • ~ 8 to 11 million people are infected • Local lesion (chagoma, palpebral edema) at the site of inoculation • Acute phase (2 -3 months) • Usually asymptomatic • If symptomatic: • Fever, anorexia • Lymphadenopathy • Mild hepatosplenomegaly • Myocarditis • Asymptomatic chronic stage (years- decades) • Symptomatic chronic stage • Cardiomyopathy (the most serious manifestation) • Megaesophagus • Megacolon • Weight loss • Can be fatal

30. Schistosomiasis • Infection of venous system by the trematodeSchistosoma • Complex life cycle • Pathology mainly due to eggs that protrude into body cavities Cercariae Sporocysts Human Adults Snail Miracidia Eggs

31. Life cycle of Schistosoma

32. Schistosomiasis • Tissue damage (granulomas) in response to eggs lodging in tissues

33. Types of Schistosomiasis

34. Important to Remember • Cardiovascular and lymphatic systems are in continuous comminucation • Bacterial diseases: Sepsis and septic shock, infections of the heart: endocarditis; rheumatic fever- an autoimmune disease after streptococcal infection; undulating fever caused by brucellosis; systemic diseases caused by bites and scratches: cat scratch disease and Pasteurella infection; vector transmitted diseases: plague, Lyme disease, Rocky Mountain spotted fever, typhus • Viral diseases • Hemorrhagic fevers: Yellow fever, Dengue fever, Ebola hemorrhagic fever (60 – 80% mortality) • Protozoan diseases: Malaria caused by Plasmodium and infects erythrocytes; Chagas disease caused by Trypanosomacruzileading to organ infection and organ megaly • Helminthic diseases: Schistosomiasis : adult couple lives in venous system, , pathology due to eggs that penetrate into urinary bladder or intestine.

35. Check your understanding • 1) Which of the following statements about severe sepsis is false? • A) Symptoms include fever and decreased blood pressure. • B) Lymphangitis may occur. • C) Symptoms are due to bacterial endotoxin. • D) It usually is caused by gram-positive bacteria. • E) It may be aggravated by antibiotics. • 2) Which of the following is NOT caused by a bacterium? • A) Epidemic typhus • B) Tickborne typhus • C) Malaria • D) Plague • E) Relapsing fever • 3) Human-to-human transmission of plague is usually by • A) Rat flea. • B) Dog flea. • C) The respiratory route. • D) Wounds. • E) Unsanitary conditions.