Chapter 20

 

Infectious Diseases Affecting the Cardiovascular and Lymphatic Systems

 

 

Endocarditis

   Inflammation of the endocardium, or inner lining of the heart

  Usually involves infection of the heart valves

   Symptoms include fever, anemia, abnormal heartbeat, and abdominal pain

  Similar to heart attack

   Acute Endocarditis

  Bacteria accumulate on the valves and lead to cardiac malfunction or clumps can break off and create blockages in vital organs

  Most often caused by: Staphylococcus aureus, Streptococcus pyogenes, Streptococcus pneumoniae, and Niesseria gonorrhea

  Transmitted via IV drug use, trauma, or surgery

   Subacute Endocarditis

  Usually preceded by congenital malformation or damage to heart valves

  Often caused by nonpathogenic flora of the mouth such as Streptococcus species

  Bacteria gain entrance to the bloodstream during dental procedures, toothbrushing, or other trauma (IV drugs or catheters)

  Antibiotics given before surgical or  dental procedures if patient is at risk

   Treat both types with antibiotics for at least one month or surgery to remove infected clots

   Untreated Endocarditis can lead to shock and death

 

 

 

Gram-negative Septicemia

   Occur when gram-negative organisms are actively multiplying in the blood

   Septicemia often orginates from an infection somewhere in the body other than the bloodstream and impaired body defenses allow the bacteria to enter the bloodstream

   Characterized by violent chills and fever

   Endotoxic shock - endotoxin released by the bacteria activate cytokines which can decrease blood pressure to vital organs and lead to shock and death

   Disseminated Intravascular Coagulation (DIC) -endotoxins activate clotting factors which cut off blood supply and cause tissue necrosis

   Can be acquired from IV lines or surgical procedures, UTIs, or other abscesses

   Antibiotics increase the release of endotoxin so treatment is difficult

 

 

 

Plague

   Caused by Yersinia pestis, an intracellular enterobacterium that is transmitted by fleas

  bacteria produce coagulation factors in flea that block the esphagus and cause regurgition of infectious material into host

  Virulence factors include a capsule and protease that dissolves blood clots (like streptokinase)

   Fleas deposit bacteria into bite wounds

   Bubonic plague - bacteria enter the regional lymph nodes, which form enlarged lesions called buboes

  fever, chills, headache, nausea

   Septicemic plague - organisms spill into the bloodstream, where endotoxin release causes shock and DIC

  dark hemorrhages in skin and mucous membranes (Black Death)

   Pneumonic plague - infection of the lung can be fatal within a few days

   The mortality rate for septicemic plague is 30-50% with treatment and 100% without treatment

   Bacteria can grow in over 200 different species of mammals

  Potential bioterrorism disease

   Controlled by quarantine, trapping rodents and killing fleas, and antibiotic treatment early

 

 

 

Tularemia (Rabbit Fever)

   Zoonotic disease widespread among wild animals

  Potential bioterrorism disease

   Acquired from skinning animals, insect bites, or inhalation

   The causative agent is Francisella tularensis

   The bacteria causes an ulcer where it enters the skin, then chills, fever, achiness, and enlarged and tender lymph nodes

   Can cause pneumonia if inhaled

   Treated with antibiotics or attenuated vaccine available

 

 

 

Lyme Disease

   A slowly progressive syndrome that mimics neuromuscular and rheumatoid conditions

   Caused by Borrelia burgdorferi transmitted through the bite of an infected tick

  bacteria are maintained in mice and deer

   Early symptoms include malaise, chills, fever, headache, stiff neck, joint pain, backache, and enlarged lymph nodes

   Erythema migrans - a bulls-eye skin rash that develops in 70% of all cases

   If left untreated, can lead to cardiac symptoms, a crippling polyarthritis, and chronic neurological complications that are severely disabling

   Treatment with antibiotics is effective early    

 

 

 

Infectious Mononucleosis (Kissing Disease)

   High incidence among people between the ages of 15 and 24

   The causative agent is the Epstein-Barr virus

   Transmitted by saliva, blood, sexual contact, or transplants

   Primary infection occurs in the epithelium of the mouth and throat, causing fever, sore throat, and fatigue

   The virus is carried to the lymph nodes where it infects B cells and causes enlargement of the lymph nodes and spleen

   Symptoms gone in 2-4 weeks but virus remains in B cells for life

  Some suffer severe exhaustion for months

   Infection with the virus has been associated with certain malignancies:

  Burkitts lymphoma

  Nasopharyngeal carcinoma

  Hodgkins and Non-Hodgkins lymphoma

 

 

 

Hemorrhagic Fever Diseases

   Characterized by extreme fevers accompanied by internal hemorrhaging

   All are caused by enveloped RNA viruses that the disrupt blood-clotting system

   Yellow Fever

  Caused by an arbovirus of the flavivirus family that multiplies in mosquitos

  Begins with fever, headache, and muscle pain and can progress to bleeding from the nose and mouth, kidney damage, and jaundice with a 50% mortality rate

   Dengue Fever

  Caused by an arbovirus of the flavivirus family that multiplies in mosquitos

  Usually mild, but can cause severe muscle and joint pain and dengue hemorrhagic shock syndrome which is lethal

   Chickungunya

  Caused by an arbovirus of the alphavirus family that multiplies in mosquitos

  Symptoms similar to Dengue Fever, accompanied by severe joint pain lasting for years

   Ebola and Marburg

  Two related viruses in the filovirus family that are maintained in the cave-dwelling fruit bat

  Transmitted by direct contact with an infected person or their body fluids

  There is no treatment or vaccine available

   Lassa Fever

  Caused by several related arenaviruses that are maintained in African rats

  Most cases are asymptomatic but can cause chest pain, hemorrhaging, sore throat, vomiting, diarrhea, encephalitis, and deafness

  Transmitted by inhalation or ingestion of rat droppings or from human secretions

  Treat with antivirals early

 

 

 

Nonhemorrhagic Fever Diseases

   Characterized by high fever but no   hemorrhaging

   All are caused by bacteria         

   Brucellosis

  Potential bioterrorism agent           

  Caused by members of the genus Brucella

  Maintained in cattle and pigs; can infect workers in the meat-packing industry, large game hunters, veterinarians, or ingesting raw dairy products

  Phagocytes carry bacteria into the bloodstream, creating lesions in the liver, spleen, bone marrow, and kidney

  Causes a fluctuating pattern of fever called Undulent Fever

  Symptoms include chills, sweating, aches, and weight loss

  Most cases recover within 2 months

  Treat with antibiotics for weeks

   Q Fever

  Potential bioterrorism agent         

  Caused by Coxiella burnetii

  Harbored by ticks and spread by contact with products from infected animals       

  Abrupt onset of fever, chills, head and muscle aches, and a rash

  Can be chronic and complications include pneumonitis, hepatitis, and endocarditis

  Treat with antibiotics or vaccine available

 

   Cat-Scratch Disease

  Caused by Bartonella henselae

  Transmitted by being clawed or bitten by a cat, usually in children

  Begins with a cluster of small papules at the site of entry, then lymph nodes swell and become pus-filled

  Treat with antibiotics

   Trench Fever    

  Caused by Bartonella quintana and carried by lice

  Symptoms vary and include a 5-6 day fever, leg pains, headache, chills, muscle aches, and a rash; endocarditis can develop

  Treat with antibiotics

   Rocky Mountain Spotted Fever

  Caused by Rickettsia rickettsii and transmitted by ticks

  Early symptoms include fever, headache, muscle and joint pain

  A spotted rash then appears on the palms, wrists, ankles, and soles

  Can involve the heart, central nervous system, and kidneys and endotoxin can cause shock from DIC

  Treatment includes the use of antibiotics early

  Two unrelated species of bacteria cause spotless Rocky Mountain Spotted Fever, a similar tick-borne disease that produces fever

 

 

 

Malaria

   Most common serious infectious disease worldwide with about 3 million deaths  annually

   Caused by 4 species of the protozoa Plasmodium that are transmitted by mosquitos

   Sporozoites injected by the mosquito are carried by the bloodstream to the liver where they produce merozoites

   Merozoites are released into the bloodstream where they infect and reproduce in red blood cells, causing them to burst open and release new merozoites

   Recurrent bouts of chills, fever and sweating result from the red blood cell cycle of growth and release

   Can cause anemia, organ rupture, cerebral malaria, coma, and death

   Medications available for travelers or treat with anti-malarial drugs

 

 

 

Anthrax

   Known bioterrorism agent          

   Caused by Bacillus anthracis

  a gram-positive, spore-forming rod found in the soil

  Virulence factors include a capsule and an exotoxin complex composed of 3 proteins

   Causes massive inflammation and shock

   Most cases are in livestock or textile workers

   Cutaneous anthrax infection of skin

   Pulmonary anthrax infection in lungs

  causes pulmonary edema and hemorrage

   Gastrointestinal anthrax through ingestion

   Anthrax meningitis infection in CNS

   Bacteria gain access to the bloodstream and death is a result of overwhelming septicemia

   Toxoid vaccine or prophylactic antibiotics available for livestock or people at risk

 

 

 

Acquired Immunodeficiency Syndrome (AIDS)

   End stage of disease caused by human immunodeficiency virus (HIV)

  appears to be a hybrid of 2 separate monkey viruses (SIV) that acquired the ability to infect humans

   Infection is sometimes followed by no obvious symptoms or only by flu-like symptoms

  fever, head and muscle aches, weight loss, enlarged lymph nodes, and a rash

   Can remain asymptomatic for 2 to 15 years

   The virus infects and destroys CD4 T helper lymphocytes and other leukocytes

  as they are destroyed the immune system weakens (leukopenia)

   Secondary infection is actually the leading cause of death

  unusual fungal infections, certain malignancies, pneumonia, diarrhea, and complications from virus infections

  later symptoms involve fatigue, fever, sore throat, night sweats, rash, memory and sensory loss, and AIDS dementia

  wasting results from weight loss, diarrhea, and poor absorption

   HIV is transmitted through sexual intercourse, sharing needles, and from mother to newborn

   Treated with highly active antiretroviral therapy (HAART)

  an anti-viral cocktail containing 2 reverse transcriptase inhibitors and 1 protease inhibitor

  1% of people infected are nonprogressors