Infectious Diseases Manifesting in the Cardiovascular and Lymphatic Systems

Chapter 21: Infectious Diseases Manifesting in the Cardiovascular and Lymphatic Systems

Overview

This chapter explores the anatomy, natural defenses, and normal biota of the cardiovascular and lymphatic systems, followed by a detailed review of major infectious diseases affecting these systems. It covers causative agents, transmission, symptoms, diagnosis, prevention, treatment, and epidemiology for each disease.

Anatomical Features of the Cardiovascular and Lymphatic Systems

Cardiovascular System

• Heart: Central organ pumping blood through arteries and veins.

• Arteries: Carry oxygenated blood and nutrients from the heart to tissues.

• Veins: Return deoxygenated blood and waste products to the heart.

• Capillaries: Sites of exchange between blood and tissues.

• White Blood Cells (WBCs): Macrophages, neutrophils, basophils, eosinophils; key players in immune response.

Lymphatic System

• Source of immune cells: Lymphocytes (B cells, T cells, NK cells).

• Lymph vessels: Transport lymph fluid.

• Lymph nodes: Filter lymph and house immune cells.

• Tonsils, spleen, thymus, bone marrow: Organs involved in immune cell production and maturation.

Natural Defenses of the Cardiovascular and Lymphatic Systems

• Innate immunity: Immediate, non-specific defense (e.g., phagocytosis by macrophages).

• Adaptive immunity: Specific, acquired defense (e.g., antibody production by B cells).

Normal Biota

• Microorganisms may be present, but there is no established normal microbiome in these systems.

• Low-level microbial "infections" may contribute to diseases with no clear infectious cause.

Key Infectious Diseases of the Cardiovascular and Lymphatic Systems

Endocarditis

Inflammation of the inner lining of the heart (endocardium), often due to infection. Can be acute or subacute.

• Acute symptoms: Rapid onset, severe symptoms.

• Subacute symptoms: Fever, anemia, abnormal heartbeat, heart attack symptoms, chills, abdominal pain, Janeway lesions, Osler's nodes, enlarged spleen, clubbed fingers/toes.

Disease	Causative Organism(s)	Most Common Modes of Transmission	Culture/Diagnosis	Prevention	Treatment	Distinctive Features	Epidemiological Features
Acute Endocarditis	Staphylococcus aureus, Streptococcus pyogenes, S. pneumoniae, Enterococcus, Pseudomonas aeruginosa, others	Parenteral	Blood culture	Aseptic surgery, injections	Vancomycin, surgery	Acute onset, high fatality	Greatly increased incidence due to heroin epidemic
Subacute Endocarditis	Alpha-hemolytic streptococci, others	Endogenous transfer of normal biota to bloodstream	Blood culture	Prophylactic antibiotics before invasive procedures	Broad-spectrum antibiotics, surgery may be necessary	Slower onset	N/A

Sepsis and Endotoxic Shock

• Occurs when organisms actively multiply in the blood.

• Gram-negative bacteria release endotoxin, causing drastic loss of blood pressure.

• Symptoms: Fever, altered mental state, shaking chills, gastrointestinal symptoms.

Causative Organism(s)	Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Bacteria or fungi	Parenteral, endogenous transfer	Cell wall or membrane components	Blood culture, deep sequencing	N/A	Broad-spectrum antibiotic until identification and susceptibilities tested	In US: 1.7 million cases, 270,000 deaths/year

COVID-19

• Causative agent: SARS-CoV-2

• Transmission: Droplet, airborne

• Virulence factors: Attachment to ACE-2 receptor, induction of autoimmunity

• Diagnosis: RT-PCR, antibody and antigen tests

• Prevention: Vaccine, mitigation efforts

• Treatment: Antivirals (e.g., paxlovid™)

• Epidemiology: Spreading worldwide

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
SARS-CoV-2	Droplet, airborne	Attachment to ACE-2; induction of autoimmunity	RT-PCR, Ab and Ag tests	Vaccine, mitigation efforts	Antivirals such as paxlovid™	Spreading constantly worldwide

Bubonic Plague

• Causative agent: Yersinia pestis

• Transmission: Biological vector (flea), droplet contact (pneumonic), direct contact with body fluids

• Virulence factors: Capsule, plasminogen activator

• Diagnosis: Rapid genomic methods

• Prevention: Flea/animal control, vaccine for high-risk individuals

• Treatment: Streptomycin or ciprofloxacin

• Epidemiology: Endemic in western/southwestern US; 95% of cases in Africa (including Madagascar); Category A bioterrorism agent

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Yersinia pestis	Biological vector (flea), droplet contact, direct contact with body fluids	Capsule, plasminogen activator	Rapid genomic methods	Flea/animal control, vaccine for high-risk individuals	Streptomycin or ciprofloxacin	Endemic in western/southwestern US; 95% of cases in Africa; Category A Bioterrorism Agent

Tularemia

• Causative agent: Francisella tularensis

• Transmission: Biological vector (tick), direct contact with infected animals, airborne

• Virulence factors: Intracellular growth

• Diagnosis: Culture (dangerous to lab workers), serology not reliable, fine needle aspirations of lymph node sometimes used

• Prevention: N/A

• Treatment: Gentamicin or streptomycin

• Epidemiology: US: several hundred cases/year; internationally: 500,000 cases/year; Category A Bioterrorism Agent

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Francisella tularensis	Biological vector (tick), direct contact, airborne	Intracellular growth	Culture (dangerous), serology not reliable	N/A	Gentamicin or streptomycin	US: several hundred cases/year; internationally: 500,000 cases/year; Category A Bioterrorism Agent

Lyme Disease

• Causative agent: Borrelia burgdorferi and related species

• Transmission: Biological vector (tick)

• Virulence factors: Antigenic shifting, adhesins

• Diagnosis: Acute and convalescent sera testing

• Prevention: Tick avoidance

• Treatment: Doxycycline/amoxicillin (3–4 weeks), cephalosporins, penicillin

• Epidemiology: US: 25,000–30,000 cases/year; endemic in North America, Europe, Asia

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Borrelia burgdorferi and related species	Biological vector (tick)	Antigenic shifting, adhesins	Acute and convalescent sera testing	Tick avoidance	Doxycycline/amoxicillin, cephalosporins, penicillin	US: 25,000–30,000 cases/year; endemic in North America, Europe, Asia

Infectious Mononucleosis

• Causative agent: Epstein–Barr virus (EBV)

• Transmission: Direct/indirect contact, parenteral

• Virulence factors: Latency, ability to incorporate into host DNA

• Diagnosis: Differential blood count, Monospot test, specific ELISA

• Prevention: N/A

• Treatment: Supportive

• Distinctive features: Lifelong persistence

• Epidemiology: US: 500 cases per 100,000/year

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Distinctive Features	Epidemiological Features
Epstein–Barr virus (EBV)	Direct/indirect contact, parenteral	Latency, ability to incorporate into host DNA	Differential blood count, Monospot test, ELISA	N/A	Supportive	Lifelong persistence	US: 500 cases per 100,000/year

Anthrax

• Causative agent: Bacillus anthracis

• Transmission: Vehicle (air, soil, food), indirect contact (animal hides)

• Virulence factors: Triple exotoxin

• Diagnosis: Culture, direct fluorescent antibody tests

• Prevention: Vaccine for high-risk population, antibiotics post-exposure

• Treatment: In consultation with CDC

• Epidemiology: Internationally, 2,000–20,000 cases annually; Category A Bioterrorism Agent

Causative Organism(s)	Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Bacillus anthracis	Vehicle (air, soil, food), indirect contact (animal hides)	Triple exotoxin	Culture, direct fluorescent antibody tests	Vaccine for high-risk population, antibiotics post-exposure	Consult CDC	Internationally, 2,000–20,000 cases annually; Category A Bioterrorism Agent

Hemorrhagic vs. Nonhemorrhagic Fevers

Hemorrhagic Fevers

• Agents infect blood and lymphatics, causing extreme fevers and internal hemorrhaging.

• RNA enveloped viruses; often transmitted by Aedes mosquitoes.

• Prevalence fluctuates with global warming patterns.

Nonhemorrhagic Fevers

• High fever without capillary fragility or hemorrhagic symptoms.

• Mostly caused by multiple bacterial species and one protozoan (Babesia).

Chagas Disease

• Causative agent: Trypanosoma cruzi

• Transmission: Biological vector (triatomine bug), vertical

• Virulence factors: Antioxidant enzymes, co-opting host antigens, induces autoimmunity

• Diagnosis: Blood smear in acute phase, serological methods in later stages

• Prevention: Insect control

• Treatment: Consult CDC

• Epidemiology: Endemic in Central/South America; 230,000 cases in US; neglected parasitic infection

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Trypanosoma cruzi	Biological vector (triatomine bug), vertical	Antioxidant enzymes, co-opting host antigens, induces autoimmunity	Blood smear (acute), serology (later)	Insect control	Consult CDC	Endemic in Central/South America; 230,000 cases in US; neglected parasitic infection

Malaria

• Causative agent: Plasmodium falciparum, P. vivax, P. ovale, P. malariae

• Transmission: Biological vector (Anopheles mosquito), vertical

• Virulence factors: Multiple host stages, antigenic variation, ability to sequester in tissues, GPI toxin, cross-hemorrhages

• Diagnosis: Blood smear, serological methods

• Prevention: Mosquito control, bed nets, chemoprophylaxis, RTS,S vaccine

• Treatment: Artemisinin-based combination therapy (WHO recommended)

• Epidemiology: US: cases in immigrants/travelers; globally: 300 million cases/year, 0.5 million deaths/year (mostly children)

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Plasmodium falciparum, P. vivax, P. ovale, P. malariae	Biological vector (mosquito), vertical	Multiple host stages, antigenic variation, tissue sequestration, GPI toxin	Blood smear, serological methods	Mosquito control, bed nets, chemoprophylaxis, RTS,S vaccine	Artemisinin-based combination therapy	Globally: 300 million cases/year, 0.5 million deaths/year

Human Immunodeficiency Virus (HIV)

• Causative agent: Human immunodeficiency virus (HIV-1 most dominant)

• Transmission: Direct contact (sexual), parenteral, vertical

• Virulence factors: Ability to infect macrophages and T cells, immune evasion

• Diagnosis: Serological tests, viral load measurement

• Prevention: Barrier protection, PrEP, PEP, needle exchange programs

• Treatment: Antiretroviral therapy (ART)

• Epidemiology: US: 1.2 million living with infection, 13% unaware; global: 38 million living with HIV

Causative Organism(s)	Most Common Modes of Transmission	Virulence Factors	Culture/Diagnosis	Prevention	Treatment	Epidemiological Features
Human immunodeficiency virus (HIV)	Direct contact (sexual), parenteral, vertical	Infects macrophages and T cells, immune evasion	Serological tests, viral load measurement	Barrier protection, PrEP, PEP, needle exchange	Antiretroviral therapy (ART)	US: 1.2 million living with infection, 13% unaware; global: 38 million living with HIV

Summary Table: Major Infectious Diseases of the Cardiovascular and Lymphatic Systems

Disease	Causative Agent	Transmission	Key Symptoms	Prevention	Treatment
Endocarditis	Staphylococcus aureus, Streptococcus spp.	Parenteral, endogenous transfer	Fever, anemia, abnormal heartbeat	Aseptic surgery, antibiotics	Vancomycin, broad-spectrum antibiotics
Sepsis	Bacteria, fungi	Parenteral, endogenous transfer	Fever, chills, low blood pressure	N/A	Broad-spectrum antibiotics
COVID-19	SARS-CoV-2	Droplet, airborne	Respiratory symptoms, fever	Vaccine, mitigation	Antivirals
Plague	Yersinia pestis	Flea, droplet, direct contact	Buboes, fever, chills	Flea/animal control, vaccine	Streptomycin, ciprofloxacin
Tularemia	Francisella tularensis	Tick, direct contact, airborne	Fever, ulcers, lymphadenopathy	N/A	Gentamicin, streptomycin
Lyme Disease	Borrelia burgdorferi	Tick	Fever, rash, joint pain	Tick avoidance	Doxycycline, amoxicillin
Mononucleosis	Epstein–Barr virus	Direct/indirect contact	Fatigue, fever, swollen lymph nodes	N/A	Supportive
Anthrax	Bacillus anthracis	Air, soil, food, animal hides	Blisters, fever, cough	Vaccine, antibiotics	Consult CDC
Chagas Disease	Trypanosoma cruzi	Triatomine bug, vertical	Fever, heart issues, digestive problems	Insect control	Consult CDC
Malaria	Plasmodium spp.	Mosquito, vertical	Fever, chills, anemia	Mosquito control, vaccine	Artemisinin-based therapy
HIV	Human immunodeficiency virus	Sexual, parenteral, vertical	Immunodeficiency, opportunistic infections	Barrier protection, PrEP, PEP	Antiretroviral therapy

Additional info:

• Hemorrhagic fevers are typically caused by RNA viruses and are associated with outbreaks in tropical regions.

• Nonhemorrhagic fevers may be caused by bacteria such as Brucella, Bartonella, and protozoa like Babesia.

• Sepsis and endotoxic shock are medical emergencies requiring rapid diagnosis and intervention.

• HIV infection progresses through acute, chronic, and AIDS stages if untreated.