Chapter 23: Diseases of the CV and Lymphatic Systems

1. Cardiovascular system = heart, blood, and blood vessels

2. Lymphatic system = lymph, lymph vessels, lymph nodes, lymphatic organs = tonsils, appendix, spleen, thymus

3. Blood and lymph carry nutrients and O2 to body tissues and carry away wastes a) they can also spread pathogens that have entered their circulationb) many of the body’s innate defensive systems are found in blood and lymph ex. Circulating phagocytic cells

Chapter 23: Diseases of the CV and Lymphatic Systems

4. Blood is a mixture of formed elements (cells) and plasma (liquid)a. some blood plasma leaves the blood capillaries and goes into the interstitial spaces as interstitial fluidb. this interstitial fluid is then picked up by lymph capillaries and now the interstitial fluid is referred to as lymph

5. Lymph capillaries are very permeable and also pick up microbes or their products

Chapter 23: Diseases of the CV and Lymphatic Systems

6. Lymph is transported to larger lymph vessels called lymphaticsa. lymphatics contain valves to keep the lymph moving towards the heartb. lymph is returned to the blood before the blood enters the heart via a veinc. the lymphatic system is a one way system from interstitial fluid to the cardiovascular system

Chapter 23: Diseases of the CV and Lymphatic Systems

7. Lymph nodes are oval shaped structures throughout the lymphatic systema. contains fixed macrophages to remove microbesb. can become infected and swollen = buboes c. contain 2 types of lymphocytes

1) B cells – Abs2) T cells – cell mediated immunity

Sepsis1. Sepsis = toxic, inflammatory condition arising

from the spread of bacteria or bacterial toxins often accompanied by lymphangitis which is inflamed lymph vessels visible as red streaks under the skin

a. Sx = fever, chills, accelerated breathing and heart rate

b. If it is accompanied by a drop in blood pressure and organ dysfunction (can be just 1 organ), it is considered to be severe sepsis

c. Septicemia = growth of bacterial pathogens in the bloodstream

1) can cause septic shock which is low BP that can’t be controlled by addition of fluids

2) usually a result of endotoxins (G- bacteria)

Sepsis

2. Gram negative sepsis = endotoxic shocka. lysis of cell causes release of endotoxins that

cause a drop in BP3. Gram positive sepsis – usually caused by

Staphylococcus and Streptococcus – produce exotoxinsa. Enterococci is one of the leading causes of

nosocomial infections – they have a natural resistance to penicillin and an acquired resistance to vancomycin

b. group B streptococci is a common cause of neonatal sepsis

Sepsis

4. Puerperal sepsis aka puerperal fever aka childbirth fevera. it is a nosocomial infection of the uterus that can lead to peritonitis (infection of the abdominal cavity) and septicemiab. caused by a group A beta hemolytic Streptococcus

1) most common is Streptococcus pyogenes

Bacterial infections of the heart

1. Endocardium = innermost layer surrounding the heart

a. Inflammation of endocardium = endocarditis

b. Subacute (meaning it develops slowly) bacterial endocarditis usually is caused by an alpha hemolytic streptococci

c. Acute bacterial endocarditis is usually caused by Staphylococcus aureus and develops much more rapidly and progressively

1) it can affect the heart valves and is often fatal

Bacterial infections of the heart

2. Pericarditis = inflammation of the sac around the heart (pericardium), usually caused by streptococci

3. Rheumatic fever is considered an autoimmune rx by the body to repeated infections by Streptococcus pyogenesa. inflammations cause arthritis and damage to heart valvesb. some people develop Sydenham’s chorea aka St. Vitus dance which is characterized by involuntary movements which resolve in several months

Tularemia aka rabbit fever

1. Tularemia – a zoonotic disease of the lymph nodes caused by Francisella tularensis (Gram neg rod)

2. Transmission – hunters in contact with small animals (rabbits –mc, ground squirrels) infected by arthropod bites (ticks, deer fly), direct contact with body fluids of infected animals, airborne

Tularemia aka rabbit fever

3. Infection results in a small ulcer at the infection site and later lymph node involvement

4. Virulence factor = microbes grow intracellular in phagocytes which protect it from chemotherapy

5. Sxs = a. acute =HA, backache, fever, chills, malaise, weakness

b. associated with portal of entry

Brucellosis

1. Aka Undulant fever- undulant means wavelike, periodic spiking of fever

2. Pathogena. Brucella abortus – common in cattleb. Brucella suis – in pigs, most common mode in US,

both can infect humans 3. Transmission

a. Occupational hazard of animal handlers – vets, ranchers, slaughterhouse

b. Transmitted through direct contact with infected animals and eating raw cheese and milk

Brucellosis

4. Once the bacteria are in the body they are ingested by macrophages which transport them via the lymphatic system to the liver, spleen, bone marrow

a. they live and reproduce within the macrophages making them resistant to Abs

Anthrax – common soil bacteria

1. Pathogen – Bacillus anthracisa. aerobic, G+, lg rods, forms endospores

b. Multiplies in large #s in the blood and septicemic anthrax is possible for all 3 forms of anthrax

2. Cutaneous anthrax - most common forma. Transmitted by contact with infected hides, wool,

animal products esp. from the Middle East

b. endospores enter through minor skin lesion, next papules appear and then vesicles appear that form a depressed, ulcer covered by a black scab (pg679)

Anthrax

2. Cutaneous anthraxc. sxs= low grade fever, malaise, usually doesn’t enter the blood

stream d. Mortality rate w/o tx = 20%, with tx <1%

3. Gastrointestinal anthrax – rare forma. acquired through the ingestion of contaminated foodsb. sxs = nausea, abdominal pain, bloody diarrheac. ulcerative lesions to GI tract (mouth to intestines)d. mortality rate > 50%

Anthrax

4. Inhalational or pulmonary anthrax – most dangerous forma. endospores are inhaled into the lungs and eventually enter the bloodstreamb. initial sxs = mild fever, coughing, chest pain

1) can be treated with Abs if suspect Anthrax

c. if bacteria enter the blood and proliferate – septic shock that kills the px within 24 – 36 hrs

1) mortality rate almost 100%

Anthrax

5. pathogenesis/virulence factorsa. endospores are ingested by macrophages where they germinate into vegetative cells, multiply and kill macrophages (< body defense) b. exotoxin complex composed of 3 separate proteins

1) protective antigen – binds toxins to target cells and permits them to enter the cells

2) edema toxin – causes local edema and interferes with phagocytosis of macrophages

3) lethal toxin – targets and kills macrophages

Anthrax

6. Dx = presumptive dx – culture on blood agar and gram stain, test to differentiate B. anthracis from B. sp.a. ex. B. anthracis is non motileb. confirmatory test done at CDC

7. Vaccination is a live, attenuated vaccine for animals, for humans it is an inactivated form of toxins consisting of 6 injections over a 18 month period plus yearly boosters

Gangrene

1. Pathogen = Clostridium perfringens an anaerobic, G+ , endospores – found in the soil

2. If a wound interrupts the blood supply to the tissue it causes a condition known as ischemia and the wound becomes anaerobic

3. Ischemia leads to necrosis (death of tissue) which results in gangrene

Gangrene

4. Gas gangrenea. as bacteria grow they ferment ms CH2Os and produce the gases CO2, H2b. bacteria produce toxins that can destroy ms tissuec. if toxins and bacteria reach the bloodstream can cause systemic illness – w/o tx condition is fatal

5. Tx = surgical removal of necrotic tissue, amputationa. if in abdominal cavity- tx w/ pressurized O2 rich environment – hyperbaric chamber, and penicillin

Systemic diseases caused by bites and scratches

1. Cat scratch diseasea. Pathogen = Bartonella henselae can live in

cat’s RBCs causing bacteremia in cats

b. Transmission = usually by bite or scratch

c. Signs and sxs = initial sign is a papule followed lymph node swelling, malaise, fever

d. Tx = usually self limiting, Abs may help

Systemic diseases caused by bites and scratches

Rat bite fever1. Streptobacillary rat bite fever

a. Pathogen = Streptobacillus moniliformis b. Transmission is by bite of urban ratsc. Sxs = fever, HA, ms ache, inflammation around the lesion

1) If it spreads to the bloodstream – swollen lymph nodes, rash, occasionally endocarditis

2. Spirillar fevera. pathogen = Spirillum minorb. transmission is bite from wild rodentsc. sxs are similar to streptobacillary rat bite feverd. tx = penicillin for both forms

Vector transmitted disease

Plague – Yersinia pestis – G neg, rod1. Normally a disease of rats, now cats are a new reservoir2. Transmitted from one rat to another by the rat flea Xenopsylla

cheopisa. If the host dies the fleas seek a new host including humansb. Fleas not always necessary, can contact by skinning infected

animals and by bites, scratches, licks from a cat3. After a flea bite bacteria enters the bloodstream and proliferate in

lymph and blooda. Lymph nodes enlarge in the groin and armpit

1) Swellings are called buboes for bubonic plagueb. Mortality rate untreated 50 – 75% < a wk after sxs appear

Vector transmitted disease

Plague

4. From the buboes the bacteria spread to the bloodstream causing septicemic plague which can cause septic shock

5. Pneumonic plague is caused when bacteria are carried by the blood to the lungs

a. mortality rate is nearly 100% w/in 3 days

b. spread by airborne droplets from humans or animals

Vector transmitted disease

Plague

6. Dx = culture and gram stain of blood or bubo aspirate, rapid diagnostic test can detect capsular antigens of Yersinia pestis

7. Tx = antibiotics Streptomycin and tetracycline

Vector transmitted disease

Relapsing fever1. All species of the genus Borrelia (a

spirochete) cause relapsing fever except for Borrelia burgdorferi which causes Lyme’s disease

2. Transmission is by soft ticks and lice3. Incidence increases during summer

months when rodent and arthropod activity increases

Vector transmitted disease

Relapsing fever4. Sxs = high fever (>105 F), shaking chills,

jaundice, rose colored rasha. after 3 to 5 days the fever subsides but returns (relapses) each time for a shorter period and less severe

5. Dx = microscopic observations of bacteria in px blood

6. Tx = tetracycline

Vector transmitted disease

Typhus – caused by rickettsias – obligate intracellular parasites of eukaryotes

1. Spread by arthropods the bacteria infect endothelial cells of the vascular system

2. The resulting inflammation causes blockage and rupture of the small blood vessels

3. Historically – a prolific killer of man, helped decimate the Aztec population in 1500s and helped the Russians defeat Napoleon's army

Typhus

Epidemic typhus (louseborne typhus)1. Pathogen – Rickettsia prowazekii is

carried in the GI tract of the body louse Pediculus humanus corporis (vector)

2. Transmission – through louse feces when host scratches bite

3. Found in crowded unsanitary conditions where lice can move from one host to another easily

Typhus

Epidemic typhus

4. Sxs = prolonged fever, stupor, rash of small red spots caused by subcutaneous hemorrhaging

5. Tx = tetracycline, chloramphenicol, eliminate conditions

6. Vaccines are available for military

Typhus

Endemic typhus – occurs sporadically rather than in epidemics

1. Murine is Latin for mouse, rodents such as rats, squirrels are hosts for this type of typhus

2. Pathogen = Rickettsia typhi which is transmitted by the rat flea Xenopsylla cheopis

3. Clinically endemic and epidemic typhus are the same but endemic typhus is less severe

4. Tx = tetracycline, 5. Prevention = rat control

Typhus

Tickborne typhus = Rocky Mt. Spotted Fever

1. Pathogen = Rickettsia rickettsia which is a parasite of ticks

a. In west - deer tick Dermacentor andersoni

b. In the east - deer tick Dermacentor variabilis

2. One week after the tick bite – macular rash develops which may be mistaken for measles except the rash can be on the palms and soles which does not occur with viral rashes

Typhus

3. Dx = fluorescent antibody, PCR

4. Prevention – avoid ticks

5. Tx = tetracycline, chloramphenicol, doxycycline, no vaccine available

6. Without tx 20% mortality rate

7. Distinguishing characteristics – m.c. in east and SE US

Viral hemorrhagic fevers

Hemorrhagic fevers are Certain viral fevers accompanied by severe hemorrhagic lesions of the tissues, most are zoonotic

Classic = they have been around for a long time

Emerging = they are fairly new

Viral hemorrhagic feversClassic

Yellow fever

1. Is caused by an arbovirus transmitted by the bite of the mosquito Aedes aegypti

2. Early sx = fever, chills, HA, followed by nausea and vomiting

3. Later sx = jaundice (yellowing of the skin and eyes) which reflects liver damage resulting in deposits of bile pigments in the skin, some px may hemorrhage from the nose and mouth

Viral hemorrhagic feversClassic

Yellow fever

4. Endemic to Africa, central and south America

5. Monkeys are the natural reservoirs but human to human transmission can occur

6. No specific tx, vaccine is live, attenuated, mortality rate – 20%

Viral hemorrhagic feversClassic

Dengue fever – aka breakbone fever, milder disease than yellow fever

1. RNA virus that is also transmitted by Aedes aegypti

2. Endemic to the Caribbean and tropical areas

3. Sx= fever, severe ms and joint pain, rash

4. no animal reservoir

Viral hemorrhagic feversClassic

5. Dx = rise in IgM titers6. Prevention = a live, attenuated vaccine is being

tested7. Dengue hemorrhagic fever is a severe form

caused when Abs from a previous infection combine with the virusa. it can induce shock in a victim (usually a child) and kill in a few hoursb. one of the leading causes of death among SE Asian children

Viral hemorrhagic feversEmerging

Hantavirus pulmonary syndrome - 19931. Pathogen – Sin Nombre virus is a

Bunyavirus found mostly in western states

2. Transmission = by inhalation of airborne viruses from dried urine or feces of infected small rodents

3. Causes a frequently fatal pulmonary infection where the lungs fill with fluids

Viral hemorrhagic feversEmerging

Hantavirus

4. Dx = serology – IgM, PCR, id Ag in tissue

5. Prevention = avoid mouse habitats and droppings

6. Tx = supportive

7. Distinctive features = rapid onset, high mortality rate

Viral hemorrhagic feversEmerging

Ebola

1. Caused by a filovirus which is threadlike RNA virus, endemic to Africa

2. transmission is by direct contact with body fluid of infected person or animal

3. Virulence = disruption of clotting factors resulting in massive hemorrhage from all orifices, mucous membranes, internal organs

4. Dx = PCR, viral culture conducted at the CDC

Burkitt’s Lymphoma

1. A fast growing tumor of the jaw in African children

2. Pathogen is the Epstein-Barr virusa. Official name is human herpesvirus 4

3. Associated with children who have had malaria which impairs their immune response to the EB virus

Protozoan Disease of the CV and Lymphatic Systems

Chagas Disease = American trypanosomiasis

1. Pathogen = Trypanosoma cruzi – a flagellated protozoan

2. Occurs in Texas, Mexico, Central America, parts, of South America (infects 40-50% or rural populations in SA)

3. Reservoir for T. cruzi is wild animals –ex. Rodents, possums, armadillos

Protozoan Disease of the CV and Lymphatic Systems

Chagas Disease

4. Arthropod vector = Reduviid bug aka the kissing bug because it bites near the lips

5. Trypanosomes grow in the gut of the bug and is passed to humans by infected bug feces being rubbed into the wound or eyes

a. blood transfusions are another way of transmission

Protozoan Disease of the CV and Lymphatic Systems

Chagas Disease6. Most dangerous to children because of

heart damage – 10% mortality7. Can cause nerve damage controlling

peristaltic action of the esophagus and colona. can result in grossly enlarged organs – megacolon, megaesophagusb. now these organs can’t transport food

Protozoan Disease of the CV and Lymphatic Systems

Toxoplasmosis1. Pathogen = Toxoplasma gondii – a spore

forming protozoan2. Cats are the definitive host and the

protozoan undergoes the sexual phase in their intestinal tract

a. Oocysts are shed in cat’s feces and ingested by intermediate hosts – ex. Mouse, cow, pig, humans

Protozoan Disease of the CV and Lymphatic Systems

Toxoplasmosis3. It is an asymptomatic infection in most persons,

in a non-immune pregnant women it can lead to congenital toxoplasmosisa. danger to fetus is stillbirth or child with severe brain damage or vision problemsb. pg women shouldn’t change litter box

4. Calif. Fatal encephalitis of sea otters caused by T. gondii from ingestion of oocysts in waste water from flushing litter box contents down toilet

Protozoan Disease of the CV and Lymphatic Systems

Malaria

1. Pathogen = Plasmodium, a protozoan parasite

2. Vector = female Anopheles mosquito

3. WW resurgence of malaria, 300 – 500 million affected ww, 2-4 million die annually

4. 4 types of Plasmodium can cause malaria – P. vivax, P. ovale, P. malariae and P. falciparum (which is the most dangerous)

Malaria

5. Virulence factor - multiple life stages

a. asexual sporozoites are in the saliva of feeding mosquitoes, when they bite a human the sporozoites enter a capillary

b. Sporozoites invade the liver cells and develop into large #s of merozoites through a process called schizogony = asexual division

Malaria

c. Merozoites are released into the circulation and enter RBCs

1) initial infection is marked by a ring trophozoite pg. 697 for pix.d. Schizogony inside the RBC produces more merozoites that cause the RBC to burst and releases them to infect more RBCs

1) when merozoites are released so are toxic compounds which cause the characteristic

fever and chills of malaria

Malaria

e. Gametocytes develop in certain infected RBCs and are ingested by another mosquito

f. the sexual phase of fertilization and sporozoite formation occur in the mosquito

6. The original drug for malaria was quinine and today they use it and its derivatives

Leishmaniasis

1. A protozoan disease that affects the internal organs or skin and mucous membranes

2. Transmission is by the bite of the female sandfly (vector)

3. Leishmania donovani causes visceral leishmaniasis

a. Occurs in much of the tropical world, in India is called kala azar

Leishmaniasis

3. b. sxs = chills and sweating like malaria1) sxs may take a year to appear after

infectionc. protozoa proliferate in the liver and spleen causing enlargement, eventually the kidney is invaded and function is lostd. if untreated – death in a year or 2e. tx – injected drugs that contain the toxic metal antimony, new oral drugs but can cause birth defects

Leishmaniasis

4. Leishmania tropical aka oriental sore – cutaneous forma. papule appears at bite site several weeks after the biteb. papule ulcerates, heals, leaves a scar

5. Leishmania braziliensis – mucocutaneous leishmaniasis aka American leishmaniasisa. destruction of the nose, mouth, and upper throat tissueb. found in the Yucatan and the rain forests of Central and South America

Leishmaniasis

6. Virulence factor – protozoa multiplies within macrophages

7. Dx = examine blood and look for parasite in WBCs, dx of cutaneous form by clinical appearance and microscopic scrapings

Schistosomiasis

1. A helminth disease caused by a small fluke

2. Adult worms coat themselves with a layer that mimics the hosts tissue to avoid body defenses

3. The female lives in a groove of the body of the male – schistosome = split body

a. Have a continuous supply of eggs

Schistosomiasis

4. Some eggs lodge themselves in tissue where the body forms granulomas to wall them off, others are excreted to find their way to a water supply and a new hosta. a snail is the intermediate host that releases free swimming cercariae that will penetrate human skin to travel through the circulatory system to the intestinal BVs where they mature into adults

1) the US doesn’t have the right kind of snails for an intermediate host

Schistosomiasis

5. three primary types of schistosomiasisa. Schistosoma haematobium – inflammation of the urinary bladder wall

1) Africa, Middle East, esp. Egyptb. Schistosoma japonicum – intestinal inflammation

1) East Asiac. Schistosoma mansoni – intestinal inflammation

1) South America, Caribbean, Puerto Rico