Infectious and Communicable Diseases for Paramedics

Overview of Communicable Diseases

• Paramedic Concern: Infectious and communicable diseases represent a serious concern for paramedics and other healthcare providers due to the risk of exposure and transmission during patient care.
• Governmental Responsibility: Multiple government agencies are tasked with protecting public health at various levels:     * National Level: Primary oversight is provided by Health Canada and the Public Health Agency of Canada (PHAC).     * Multi-Jurisdictional Level: Responsibility is shared across federal, provincial, and territorial governments.
• Paramedic Responsibility: It is the direct responsibility of the paramedic to help prevent the spread of diseases and prioritize patient safety by maintaining a clean environment and utilizing proper protection.

Host Defence Mechanisms

The human body utilizes several primary barriers and systems to protect against invading pathogens:

• Physical Barriers:     * Skin: The primary external barrier against environmental pathogens.     * Mucous Membranes: Protective linings found in respiratory, digestive, and urogenital tracts.
• Internal Defences:     * GI Tract Secretions: Acids and enzymes in the gastrointestinal system that neutralize ingested organisms.     * Immune Response: Specialized cells that identify and destroy pathogens, specifically $B$ cells and $T$ cells.

The Cycle of Infection and Transmission

• Breaking the Cycle: The cycle of infection is most effectively and easily broken through diligent handwashing.
• Transmission Routes:     * Direct Contact: Physical contact between an infected person and a susceptible host.     * Indirect Contact: Contact with a contaminated object (fomite).     * Inhalation: Breathing in airborne droplets or particles containing pathogens.     * Puncture: Needlestick injuries or other penetrations by contaminated sharps.     * Transfusion: Introduction of contaminated blood or blood products directly into the bloodstream.     * Vector-borne: Transmission of infection to humans or other animals via an intermediary organism, such as an insect.

Biological Agents and Key Terminology

• Types of Organisms: Pathogenic agents include:     * Bacteria     * Viruses     * Fungi     * Parasites     * Protozoans     * Helminths (parasitic worms)
• Virulence: Defined as the ability of a specific organism to invade a host and create disease.
• Host Resistance: The inherent ability of a host's body to fight off or resist an infection.
• Incubation Period: The specific timeframe between the initial exposure to a pathogen and the appearance of the first symptoms of illness.
• Communicable Period: The specific window of time during which an infected individual can transmit the disease to another person.
• Carrier: An individual who harbors a disease-causing organism but does not display symptoms of illness themselves.
• Reservoir: A place where pathogens live and multiply (e.g., air-conditioning systems, standing water).

Public Health Infrastructure and Routine Practices

• Leading Organizations:     * World Health Organization (WHO)     * Centers for Disease Control (CDC) in the USA     * Provincial and local health departments, such as the Institut national de santé publique du Québec (INSPQ)
• Agency Functions: These departments are responsible for data collection, patient follow-up, and managing immunization programs. Every province maintains a mandatory list of communicable diseases that healthcare providers are legally required to report.
• Standardized Routine Practices:     * Introduced by Health Canada in $1999$.     * Represents a comprehensive standard of practice designed to replace older, less stringent protocols.     * Relies heavily on the provider's knowledge of signs, symptoms, and transmission risks.

Components of Routine Practices and PPE

• Core Prevention Components:     * Hand hygiene.     * Use of Personal Protective Equipment (PPE).     * Sharps safety (preventing needlesticks).     * Considerations for patient accommodation and transport.     * Routine cleaning of medical equipment.     * Routine cleaning and disinfection of the ambulance vehicle.
• Handwashing Protocols: Health Canada identifies handwashing as the single most important procedure for infection prevention. It must be performed:     * At the start and end of every shift.     * Before and after any patient contact.     * During and immediately after the removal of PPE.     * Before performing any invasive medical procedures.     * After cleaning or disinfecting the vehicle or equipment.     * Before leaving the hospital facility.     * Before and after handling food or smoking.     * After personal bodily functions (using the bathroom, sneezing, or coughing).     * Whenever hands are visibly soiled or when the last wash cannot be recalled.
• Essential PPE Kit:     * Disposable gloves.     * Protective eyewear.     * Cover gowns.     * Surgical masks.     * $N-95$ respirators (or similar submicron respirators).     * Alcohol-based waterless handwashing foam or gel.     * Needlesafe or needleless devices.     * Biohazard bags for contaminated waste.     * Resuscitative equipment (to avoid mouth-to-mouth contact).

Postexposure and Infection Control Planning

• Postexposure Management: Considered the "third line of defence." If exposure occurs, the paramedic must seek medical care immediately. The investigation begins with the source individual.
• Infection Control Manual Components: Every EMS agency or jurisdiction follows a plan (Table $39-4$) including:     * Exposure determination.     * Education and training.     * Hepatitis $B$ vaccine programs.     * Tuberculosis ($TB$) testing programs.     * Engineering controls and work practices.     * Medical waste management.     * Recordkeeping and compliance monitoring.

General Assessment and Management Principles

• Assessment Steps:     1. Scene evaluation.     2. Implementation of routine precautions.     3. Initial assessment.     4. Focused history and physical examination.
• Common Chief Complaints: Fever, nausea, rash, pleuritic chest pain, and difficulty breathing.
• Management Focus: Prioritize life-threatening conditions and maintain an empathetic attitude toward the patient.

Childhood and Common Infectious Conditions

• Measles: A highly communicable airborne disease presenting with fever, conjunctivitis, a blotchy red rash, and coughing.
• Rubella: Characterized by a low-grade fever, headache, swollen lymph nodes, and a diffuse rash; most common in $winter$ and $spring$.
• Mumps: A viral disease transmitted via saliva droplets ($winter/spring$). Symptoms include fever and swelling of a salivary gland. The incubation period is $12$ to $26$ days.
• Chickenpox: Highly contagious, presenting with fever, photosensitivity, and a vesicular rash that crusts into scabs.
• Pertussis (Whooping Cough): A bacterial infection causing paroxysmal coughing that can persist for $1$ to $2$ months.
• Meningitis: Inflammation of the brain and spinal cord coverings. It can be viral or bacterial. Meningococcal meningitis has an incubation period of $2$ to $10$ days. Signs include sudden-onset fever, severe headache, stiff neck, photosensitivity, pink rash, altered mental status, and projectile vomiting.
• Tuberculosis (TB): Assessment reveals a persistent cough lasting more than $3$ weeks, night sweats, headache, weight loss, hemoptysis (coughing up blood), and chest pain.
• Other Respiratory Conditions: Includes Pneumonia, Bronchiolitis, Bronchitis, Laryngitis, Croup, and Epiglottitis.
• Respiratory Syncytial Virus (RSV): The leading cause of lower respiratory tract infections. It begins like an upper respiratory infection but can progress to pneumonia, bronchiolitis, or tracheobronchitis.
• Mononucleosis: Caused by the Epstein-Barr virus ($EBV$) and transmitted via oral secretions. Symptoms: fever, sore throat, swollen lymph glands, anorexia, headache, muscle pain, and enlargement of the liver and spleen.
• Influenza: Transmitted via coughing and sneezing. Symptoms: systemic fever, chills, headache, muscle pain, malaise, anorexia, dry cough, and nasal discharge. Managed effectively with vaccines.

Skin Infestations and Parasites

• Scabies: Caused by a parasite through direct skin-to-skin contact. Symptoms include nocturnal (nighttime) itching and a rash on the hands, wrists, ankles, toes, genitals, buttocks, and abdomen.
• Lice: Small insects that live in hair and feed on blood. Transmitted via direct contact with an infested person. Signs include itching and visible nits (eggs) on hair shafts.

Viral Hepatitis

Inflammation of the liver caused by one of five distinct viruses ($A, B, C, D, E$). While the causes differ, general symptoms include anorexia, nausea, vomiting, jaundice (yellowing of skin/eyes), fatigue, malaise, low-grade fever, and vague abdominal discomfort.

• Hepatitis A: Transmitted via the fecal–oral route. The incubation period is $2$ to $4$ weeks. Prevented by gloves and handwashing.
• Hepatitis B (HBV): Incubation period is $45$ to $200$ days. Full recovery can take $3$ to $4$ months. A vaccine is available.
• Hepatitis C (HCV): The most common chronic blood-borne infection and leading cause of liver transplants. Incubation is $2$ to $24$ weeks. No vaccine exists.
• Hepatitis D (HDV): Also called "delta hepatitis." Requires a co-infection with $HBV$ to occur. High incidence in IV drug users.
• Hepatitis E: Caused by contaminated drinking water (common in developing nations). Incubation is $15$ to $64$ days. Prevention requires cleaning contaminated equipment.

Global and Emerging Infections

• HIV/AIDS: Estimated $60 \times 10^{6}$ cases worldwide. HIV is primarily sexually transmitted but can appear as acute febrile illness with malaise and swollen lymph glands. AIDS is the end-stage disease where patients are vulnerable to opportunistic infections. Prevention focuses on glove use.
• West Nile Virus: Transmitted by mosquitoes with an incubation of $3$ to $14$ days. Only $20\%$ of patients are symptomatic ($fever$, $headache$, $rash$), but it may cause encephalitis or meningitis.
• Lyme Disease: Tick-borne disease characterized by an early "bull’s-eye" rash and flu-like symptoms; can lead to arthritis.
• Rabies: Transmitted via bites from infected animals. Progresses from nonspecific symptoms to seizures, bizarre behavior, and hydrophobia.
• Tetanus: Spores enter via puncture wounds or contaminated drugs, causing severe muscle contractions.
• MRSA (Methicillin-Resistant Staphylococcus Aureus): Transmitted via unwashed hands of healthcare workers. Causes soft-tissue infections and sepsis.
• VRE (Vancomycin-Resistant Enterococci): Primarily a nosocomial (hospital-acquired) infection transmitted via contaminated surfaces.
• SARS (Severe Acute Respiratory Syndrome): Transmitted via close contact; starts as flu-like and progresses to severe respiratory distress.
• SARS-CoV-2 (COVID-19): Discovered in Wuhan, China (December $2019$); declared a pandemic by the WHO in March $2020$. Absorbed through the respiratory route, it causes ARDS. Immunodeficient patients face up to a $25\%$ fatality rate.
• MERS (Middle Eastern Respiratory Syndrome): Caused by Coronavirus $MERS-CoV$. No cure; treatment is supportive care for fever, cough, and shortness of breath.
• Viral Hemorrhagic Fevers (VHF): Includes Ebola, Marburg, Lassa, and Hantavirus. Spread via direct contact with blood/body fluids. Symptoms (fever, pain, weakness) occur $8$ to $10$ days after exposure (up to $21$ days).

Sepsis and Septic Shock

• SIRS (Systemic Inflammatory Response Syndrome) Criteria: Defined by having at least $2$ of the following:     * Temperature: $> 100.4^{\circ}F$ or $< 96.8^{\circ}F$.     * Heart Rate (HR): $> 90$.     * Respiratory Rate (RR): $> 20$ (or $PCO_2 < 32\,mmHg$).     * WBC Count: $> 12,000$, $< 4,000$, or $> 10\%$ bands.
• Sepsis: $2$ SIRS criteria plus a confirmed or suspected infection.
• Severe Sepsis: Sepsis plus signs of end-organ damage, hypotension, or lactate levels $> 4\,mmol$.
• Septic Shock: Severe sepsis with persistent hypotension ($SBP < 90\,mmHg$) despite fluid resuscitation.

Acute Respiratory Distress Syndrome (ARDS)

• Definition: Noncardiogenic pulmonary edema characterized by damaged alveoli and bilateral pulmonary infiltrates on radiography, in the absence of heart failure ($PCWP < 17\,mm\,Hg$).
• Hypoxemia Thresholds ($PaO_2/FiO_2$ Ratio):     * Mild: $200-300\,mmHg$.     * Moderate: $100-200\,mmHg$.     * Severe: $< 100\,mmHg$.
• Causes (Cytokine Storm):     * Direct Injury: Pneumonia, aspiration of gastric content, near drowning, toxic inhalation, blunt trauma (contusion).     * Indirect Injury: Sepsis (most common), pancreatitis, multiple transfusions, fat embolism, amniotic fluid embolism.

Questions & Discussion

• The presentation concludes with an open segment for "Any Qweesssstions" from the audience.