Blood and Lymphatic System Infections Review 25

Blood and Lymphatic System Infections

• Key Verse: Leviticus 17:11 states the importance of blood in atonement for the soul.

A Glimpse of History

• Alexandre Emile John Yersin (1863–1943):

  • Physician who volunteered at Pasteur Institute.

  • Recognized for work on plague in Vietnam (1894).

  • Discovered Yersinia pestis, the causative agent of plague.

Circulation of Blood and Lymph

• Functions:

  • Supplies nutrients and oxygen (O2) to cells.

  • Removes waste and helps in body temperature regulation.

• Systemic Infections: Dangerous as infectious agents can spread throughout the body.

  • Bacteremia, Viremia, Fungemia: Presence of bacteria, viruses, or fungi in the blood.

  • Sepsis: Severe illness from circulating pathogens or toxins; can cause septic shock.

Anatomy, Physiology, and Ecology

• Cardiovascular System:

  • Components: Heart, blood vessels, blood.

  • Heart Structure: Muscular pump with four chambers; valves prevent backflow.

• Blood Vessels:

  • Arteries: Thick walls, bright red blood due to oxygen.

  • Veins: Dark red blood, valves prevent backflow.

• Lymphatic System:

  • Composed of lymph, lymph vessels, lymph nodes.

  • Functions: Phagocytic cells remove infectious agents.

• Spleen:

  • Contains red pulp (filters blood) and white pulp (lymphoid tissue). Produces new blood cells and contains immune cells.

Bacterial Diseases of the Blood Vascular System

• Bacterial Infections: Rare but can lead to severe outcomes; enter bloodstream usually via lymph.

  • Endocarditis:

  • Acute vs. Subacute: Caused by different virulence levels of bacteria.

  • Symptoms include fever, fatigue.

• Sepsis: Caused by Gram-positive or Gram-negative bacteria.

Bacterial Diseases of the Lymph Nodes and Spleen

• Plague (Black Death):

  • Symptoms: Fever, buboes, cough, bleeding rash.

  • Causative Agent: Yersinia pestis, a Gram-negative rod.

  • Pathogenesis: Bacterial biofilms block flea digestion, leading to transmission during biting.

  • Epidemiology: Historically devastating, still endemic in some reservoirs such as rodents.

• Treatment: Prompt antibiotic treatment essential; prevention includes pest control.

Viral Diseases of the Lymphoid and Blood Vascular Systems

• Infectious Mononucleosis:

  • Causative Agent: Epstein-Barr virus (EBV).

  • Symptoms include fever and swollen lymph nodes indicating B cell infection.

• Pathogenesis: EBV infects throat epithelium, replicates, and targets B cells leading to immune responses.

• Epidemiology: Common in crowded conditions; transmitted via saliva.

  • No vaccine; antivirals exist for severe cases but not for latent infections.

Summary of Key Diseases

• Bacterial Infections:

  • Subacute Bacterial Endocarditis: Caused by normal flora entering bloodstream; treatable with antibiotics.

  • Plague: Serious disease with multiple forms; preventative measures include rodent control.

• Viral Infections:

  • Infectious Mononucleosis: Fever and lymphoid proliferation; limited treatment options available.

Conclusion

• Understanding these infections aids in prevention and management of the diseases linked to blood and lymphatic systems.

Earning Objectives

1. Influence of the Circulatory and Lymphatic Systems on Generalized Infectious Diseases

   • The circulatory system supplies nutrients and oxygen to cells while removing waste; dysfunction can lead to the spread of infections.

   • The lymphatic system filters body fluids and houses phagocytic cells that remove infectious agents, impacting the development and severity of infections in the body.

   • Systemic infections can occur when pathogens enter the bloodstream or lymphatic system, leading to conditions such as bacteremia, viremia, or sepsis.

2. Symptoms, Causes, Virulence Factors, Pathology, Occurrence, Prevention, and Treatment

   • Subacute Bacterial Endocarditis

     • Symptoms: Fever, fatigue.

     • Causes: Normal flora entering the bloodstream, usually in patients with pre-existing heart conditions.

     • Virulence Factors: Ability of bacteria to adhere to heart valves.

     • Pathology: Bacteria create vegetations on heart valves, leading to destruction or embolism.

     • Occurrence: Rare, more common in those with pre-existing conditions.

     • Prevention: Prophylactic antibiotics before dental or surgical procedures for at-risk individuals.

     • Treatment: Antibiotics to eliminate the infection.

   • Infectious Mononucleosis

     • Symptoms: Fever, swollen lymph nodes.

     • Causes: Epstein-Barr Virus (EBV).

     • Virulence Factors: EBV's ability to infect B cells and induce an immune response.

     • Pathology: Infection of throat epithelium, leading to systemic infection in B cells.

     • Occurrence: Common, especially in adolescents and young adults.

     • Prevention: Avoiding sharing drinks or utensils; no vaccine available.

     • Treatment: Supportive care; antivirals for severe cases.

3. Plague

   • History: Caused by Yersinia pestis, historically known as Black Death.

   • Symptoms: Fever, buboes, cough, and bleeding rash.

   • Causes: Infection from bite of infected flea or contact with infected animals.

   • Virulence Factors: Bacterial biofilms block flea digestion, facilitating transmission.

   • Pathology: Rapidly spreads in hosts through the bloodstream.

   • Clinical Manifestations: Septicemic plague, pneumonic plague, or bubonic plague.

   • Transmission Methods: Vector-borne, direct contact, and respiratory droplet from infected individuals.

   • Prevention Strategies: Rodent control, flea prevention, and public health measures.

   • Treatment Approaches: Prompt antibiotic treatment is essential; supportive care for severe cases.