INFECTIOUS DISEASES

Infection

The invasion and multiplication of microorganisms in body tissues, which may cause local cellular injury due to competitive metabolism, toxins, or antigen-antibody responses

Infectious disease

The actual pathologic consequences and physical symptoms resulting from the infection

Colonization

Microorganisms are present and multiplying without causing host interference, tissue invasion, or symptoms

Yes

Can colonized patients still spread bacteria?

prevents

[ETIOLOGY & THE CHAIN OF INFECTION]

Interrupting the chain of infection effectively __________ the spread of disease.

Causative agent

[ETIOLOGY & THE CHAIN OF INFECTION]

The pathogen (bacteria, viruses, fungi, protozoa)

Reservoir

[ETIOLOGY & THE CHAIN OF INFECTION]

Where the organism lives and grows (humans, animals, contaminated surfaces)

Portal of exit

[ETIOLOGY & THE CHAIN OF INFECTION]

How the pathogen leaves the reservoir (respiratory tract, GI tract, blood)

Susceptible host

[ETIOLOGY & THE CHAIN OF INFECTION]

The person at risk

Portal of entry

[ETIOLOGY & THE CHAIN OF INFECTION]

How it enters the new host (mucous membranes, non-intact skin)

Mode of transmission

[ETIOLOGY & THE CHAIN OF INFECTION]

How it travels (direct contact, droplet, airborne)

Intrinsic factors

[RISK FACTORS & SUSCEPTIBILITY]

• Extreme age

• Malnutrition

• Chronic illness (e.g., Diabetes, COPD)

• Immunosuppression

Extrinsic factors

[RISK FACTORS & SUSCEPTIBILITY]

• Invasive devices (Foley catheters, IV lines)

• Surgical procedures

• Broad-spectrum antibiotics that wipe out normal body flora

Incubation period

[PATHOPHYSIOLOGY/STAGES OF THE INFECTIOUS PROCESS]

Time from pathogen entry to the onset of the first symptom (Patient is infected but doesn’t know it yet)

Prodromal stage

[PATHOPHYSIOLOGY/STAGES OF THE INFECTIOUS PROCESS]

• Onset of vague, non-specific symptoms like malaise or low-grade fever

• The most contagious stage!

Acute/Illness stage

[PATHOPHYSIOLOGY/STAGES OF THE INFECTIOUS PROCESS]

• Pathogen is replicating rapidly

• Specific, severe signs and symptoms manifest

Convalescent stage

[PATHOPHYSIOLOGY/STAGES OF THE INFECTIOUS PROCESS]

Containment of the infection; tissue repair and resolution of symptoms begin

• Fever (with chills and sweating)

• Tachycardia (elevated HR) and Tachypnea (elevated RR)

• Malaise and fatigue

[CLINICAL MANIFESTATIONS/SIGNS AND SYMPTOMS OF INFECTIOUS DISEASE]

Systemic symptoms (whole body)

• Pain, tenderness, redness, and swelling

• Purulent discharge from surgical incisions or IV/drain exit sites

[CLINICAL MANIFESTATIONS/SIGNS AND SYMPTOMS OF INFECTIOUS DISEASE]

Localized symptoms (specific site)

• CBC (elevated WBCs/leukocytosis)

• Erythrocyte Sedimentation Rate (ESR)

• C-Reactive Protein (CRP) - to detect systemic inflammation

[DIAGNOSTIC EVALUATION FOR INFECTIOUS DISEASE]

Laboratory blood tests

• Blood

• Urine

• Sputum

• Wound cultures

[DIAGNOSTIC EVALUATION FOR INFECTIOUS DISEASE]

Cultures

Obtain culture specimens and ensure that result is available

What should you do before starting the first dose of antibiotics?

Chest X-rays to detect respiratory infections like pneumonia

[DIAGNOSTIC EVALUATION FOR INFECTIOUS DISEASE]

Radiology

Hand hygiene

[INFECTION PREVENTION & CONTROL: STANDARD PRECAUTIONS]

Meticulous hand washing for at least 20 seconds to dissolve fatty materials and oils. Use alcohol-based rubs for non-visibly soiled hands.

Personal protective equipment (PPE)

[INFECTION PREVENTION & CONTROL: STANDARD PRECAUTIONS]

Gloves, gowns, masks, or eye protection based on the anticipated exposure to blood or body fluids

Safe work practices

[INFECTION PREVENTION & CONTROL: STANDARD PRECAUTIONS]

Proper sharps disposal and environmental cleaning

Airborne

[TRANSMISSION-BASED PRECAUTIONS]

• Pathogens are easily aerosolized

• Requires a negative pressure room and an N95 respirator

• e.g., Measles, TB, Varicella (chickenpox)

Droplet

[TRANSMISSION-BASED PRECAUTIONS]

• Large droplets

• Requires a surgical mask when within 3 feet of the patient

• e.g., Sepsis/Strep, Pneumonia/Pertussis, Influenza, Diphtheria, Epiglottitis, Rubella, Mumps, Adenovirus

Contact

[TRANSMISSION-BASED PRECAUTIONS]

• Spread by touch

• Requires gown and gloves

• e.g., MDROs (MRSA/VRE), Respiratory infections, Skin infections, Wound infections, Enteric (C. diff), Eye infections

• Antimicrobial therapy - targeted antibiotics, antivirals, or anti-fungals based on culture sensitivities

• Symptom control - antipyretics (acetaminophen) for fever, analgesics for localized pain

• Supportive therapy - IV fluids for hydration and electrolyte balance

Medical management for infectious disease:

• Monitor vital signs routinely (watch for temperature spikes and tachycardia)

• Monitor daily WBC counts

• Assess the color and character of respiratory secretions and urine

Nursing assessments for infectious disease

• Maintain strict asepsis for wound care, dressing changes, and IV therapy

• Encourage the intake of protein-rich and calorie-rich foods to fuel immune response and tissue healing

• Provide continuous client and caregiver education regarding infection control

Nursing interventions for infectious disease

Surgical asepsis (sterile technique)

• Crucial for preventing the introduction of pathogens during invasive procedures (e.g., catheter insertion)

• Avoid talking, coughing, or sneezing over sterile fields

Acute confusion, lethargy, or falls

Older adults possess a weakened immune response. They often do not present with a classic high fever. Instead, the first sign of an infection (like a UTI) in an elderly patient is often what?

Malaria

[VECTOR-BORNE & VEHICLE-BORNE DISEASES]

• A life-threatening vehicle/vector disease caused by Plasmodium species

• Transmitted by the bite of an infected female Anopheles mosquito

Parasite multiples in the liver, then invades and destroys RBCs, leading to hemolytic anemia and microvascular blockages

Pathophysiology of malaria

• Cyclical severe chills (rigors)

• High fever

• Profuse sweating

• Jaundice (due to RBC breakdown)

• Profound fatigue

S/S of malaria:

Microscopic examination of thick and thin blood smears

Diagnosis for malaria

• Administer antimalarials (Chloroquine, Artemisinin)

• Monitor fluid balance

• Assess for signs of severe anemia

• Educate on mosquito nets/prophylaxis for travelers

Medical/nursing management of malaria:

West Nile Virus (WNV)

[VECTOR-BORNE & VEHICLE-BORNE DISEASES]

• A viral infection commonly transmitted by mosquitoes that can lead to severe neurological disease

• Flavivirus transmitted by Culex mosquitoes; birds are the primary reservoir

Virus replicates in the skin/lymph nodes, crosses the blood-brain barrier, and causes inflammation of brain tissue (encephalitis) or meninges (meningitis)

Pathophysiology of west nile virus

Aedes aegypti

[VECTOR-BORNE & VEHICLE-BORNE DISEASES]

Dengue virus (4 serotypes) transmitted by what mosquito?

Classic dengue fever (DF)

[VECTOR-BORNE & VEHICLE-BORNE DISEASES - DENGUE]

• Self-limiting systemic viral inflammation. Capillaries remain intact

• Breakbone fever: sudden high fever, retro-orbital pain, severe myalgia/joint pain, and late maculopapular rash

• Extremely low shock risk

Dengue hemorrhagic fever (DHF)

[VECTOR-BORNE & VEHICLE-BORNE DISEASES - DENGUE]

• Severe complication. Massive capillary permeability (leakage) causes fluid shift and hemoconcentration

• Plasma leakage: ascites, pleural effusion

• Bleeding: petechiae, ecchymosis, melena

• Dengue Shock Syndrome (DSS): restlessness, cold/clammy skin, rapid weak pulse, hypotension

• Tourniquet test - Positive test show numerous petechiae (indicates capillary fragility)

• Labs: Thrombocytopenia (platelets < 100,000/m³)

• DHF hallmark: Hematocrit increases > 20% (indicates severe plasma leak and hemoconcentration)

[VECTOR-BORNE & VEHICLE-BORNE DISEASES - DENGUE]

Diagnostic evaluation

• Aggressive IV fluid replacement (isotonic crystalloids like NSS/LR) to prevent hypovolemic shock

• Acetaminophen for fever

• CONTRAINDICATED: Aspirin and NSAIDs (severely increases hemorrhage risk)

[VECTOR-BORNE & VEHICLE-BORNE DISEASES - DENGUE]

Medical management:

Varicella (chickenpox)

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

• Highly contagious primary systemic infection caused by VZV

Enters via respiratory tract, replicated in lymph nodes, and causes widespread viremia resulting in diffuse skin lesions

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

Pathophysiology of varicella

• Fever

• Malaise

• Generalized pruritic (itchy) rash progressing from macules to papules to vesicles to crusts

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

S/S of varicella

• Airborne and contact precautions

• Educate patients not to scratch (prevents secondary bacterial infection)

• Administer antihistamines for pruritus

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

Nursing interventions for varicella

Herpes Zoster (Shingles)

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

• A painful, vesicular skin eruption caused by the reactivation of the varicella-zoster virus

• Etiology: prior history of chicken pox

• Risk factors: immunocompromised state, aging, severe stress

VZV lies dormant in sensory nerve ganglia. Upon reactivation, it travels down the sensory nerve to the skin, causing severe neuropathic pain and a unilateral vesicular rash

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

Pathophysiology of shingles

• Pain/burning (prodormal phase) followed by clustered, fluid-filled blisters that follow a specific dermatome (does not cross the body’s midline)

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

S/S of shingles

Measles (rubella)

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

Highly contagious viral respiratory illness with a characteristic widespread rash

Virus infects the respiratory tract, leading to systemic dissemination

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

Pathophysiology of measles

• The 3 C’s: cough, coryza (runny nose), conjunctivities

• Koplik spots (tiny white spots inside the mouth) appear before the maculopapular rash

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

S/S of measles

• Strict airborne precautions

• Supportive care, hydration, and administering Vitamin A as ordered (shown to decrease pediatric mortality)

[ERUPTIVE DISEASES/VIRAL EXANTHEMS]

Nursing focus for measles

Human immunodeficiency virus (HIV)

[BLOOD-BORNE DISEASES]

• A retrovirus that causes immunosuppression, making the patient susceptible to opportunistic infections

• Etiology/Risk: Unprotected sex, sharing IV drug needles, accidental needle sticks (healthcare workers)

HIV binds to the CD4+ T-cell receptors, fusing with the cell and using reverse transcriptase to replicate. It destroys the CD4+ T-cells, obliterating the immune system

[BLOOD-BORNE DISEASES]

Pathophysiology of HIV

• Often asymptomatic initially

• Progressive fatigue

• Lymphadenopathy

• Night sweats

[BLOOD-BORNE DISEASES]

S/S of HIV

When CD4+ count drops below 200 cells/mm³

[BLOOD-BORNE DISEASES]

When does diagnosis of HIV occur?

Antiretroviral therapy (ART) - must be taken exactly as prescribed to maintain viral suppression

[BLOOD-BORNE DISEASES]

Medical management for HIV

• Standard precautions

• Monitor for opportunistic infections (e.g., oral thrush, pneumocystis pneumonia)

• Provide intense psychosocial support and medication adherence counseling

[BLOOD-BORNE DISEASES]

Nursing interventions for HIV

Hepatitis B Virus (HBV)

[BLOOD-BORNE DISEASES]

A viral infection that attacks the liver, causing acute and chronic liver disease

Blood, semen, or other body fluids (often perinatal from mother to baby, or via needle sticks)

[BLOOD-BORNE DISEASES]

Transmission of HBV

Virus enters hepatocytes (liver cells), triggering a cytotoxic immune response that causes liver inflammation and necrosis

[BLOOD-BORNE DISEASES]

Pathophysiology of HBV

• RUQ Abdominal pain

• Dark urine

• Clay-colored stools

• Jaundice

• Extreme fatigue

[BLOOD-BORNE DISEASES]

S/S of HBV

• Encourage bed rest during acute phase to promote liver healing

• Administer Hepatitis B vaccine (Prevention!)

• Teach the patient to avoid alcohol and hepatotoxic drugs (like Acetaminophen)

[BLOOD-BORNE DISEASES]

Nursing focus for HBV

Hepatitis C (HCV)

[BLOOD-BORNE DISEASES]

Blood-borne virus causing chronic liver inflammation; the leading cause of liver transplantation

Similar to HBV but has a high rate of mutating and evading the immune system, leading to chronic infection, liver cirrhosis, and hepatocellular carcinoma

[BLOOD-BORNE DISEASES]

Pathophysiology of HCV

• Curative direct-acting antivirals (DAAs) are available

• Educate patients on bleeding precautions if cirrhosis is present

• Emphasize that there is NO vaccine for Hepatitis C

[BLOOD-BORNE DISEASES]

Management and nursing of HCV

Pulmonary tuberculosis (TB)

[RESPIRATORY DISEASES]

An infectious disease that primarily affects the lung parenchyma, caused by Mycobacterium tuberculosis

Mycobacterium tuberculosis

[RESPIRATORY DISEASES]

What bacterium causes TB?

Inhaled bacilli multiply in the alveoli. The immune system encapsulates the bacteria, forming a “Ghon tubercle” (granuloma). If the immune system weakens, the granuloma bursts, causing active TB

[RESPIRATORY DISEASES]

Pathophysiology of TB

• Low-grade fever

• Night sweats

• Fatigue

• Weight loss

• Persistent cough with hemoptysis (blood-tinged sputum)

[RESPIRATORY DISEASES]

S/S of TB

• Mantoux skin test

• QuantiFERON-TB Gold

• Sputum culture for Acid-Fast Bacilli

• Chest X-ray

[RESPIRATORY DISEASES]

Diagnosis for TB

• Strict airborne precautions (N95 mask, negative pressure room)

• Direct Observation Therapy (DOTS) to ensure adherence to 6-9 months of anti-TB drugs

[RESPIRATORY DISEASES]

Nursing interventions for TB

• Rifampicin - turns urine orange

• Isoniazid - causes neuropathy, give vitamin B6

• Pyrazinamide

• Ethambutol - vision changes, optic neuritis

[RESPIRATORY DISEASES]

Medications for TB (updated)

Community-acquired pneumonia (CAP)

[RESPIRATORY DISEASES]

Inflammation of the lung parenchyma caused by microorganisms (most commonly Streptococcus pneumoniae)

Streptococcus pneumoniae

[RESPIRATORY DISEASES]

What bacterium most commonly causes CAP?

Inflammatory response in the alveoli produces exudate that interferes with the diffusion of oxygen and carbon dioxide

[RESPIRATORY DISEASES]

Pathophysiology of CAP

• Sudden onset of chills

• Rapidly rising fever

• Pleuritic chest pain aggravated by deep breathing/coughing

• Tachypnea

[RESPIRATORY DISEASES]

S/S of CAP

• Auscultate lungs (crackles/ronchi)

• Encourage coughing and deep breathing, use of an incentive spirometer, and adequate hydration to thin secretions

[RESPIRATORY DISEASES]

Nursing assessment for CAP

Clostridioides difficile (C. diff)

[ENTERIC/DIARRHEAL DISEASES]

• A spore-forming bacterium that causes severe, hospital-acquired pseudomembranous colitis

• Etiology: Follows the use of broad-spectrum antibiotics that destroy normal intestinal flora

Bacteria release toxins (Toxin A and B) that cause massive inflammation, bleeding, and necrosis of the colon lining

[ENTERIC/DIARRHEAL DISEASES]

Pathophysiology of C. diff

• Profuse, foul-smelling, watery diarrhea

• Abdominal cramping

• Leukocytosis

[ENTERIC/DIARRHEAL DISEASES]

S/S of C. diff?

• Strict contact precautions (gown and gloves)

• Hand hygiene must be done with soap and water (alcohol sanitizer does not kill spores)

• Equipment must be cleaned with bleach-based wipes

[ENTERIC/DIARRHEAL DISEASES]

Nursing interventions for C. diff

Salmonellosis

[ENTERIC/DIARRHEAL DISEASES]

Etiology: Infection caused by Salmonella bacteria, usually from consuming undercooked poultry, eggs, or unpasteurized milk

Bacteria invade the intestinal mucosa, triggering an inflammatory response that leads to fluid hypersecretion

[ENTERIC/DIARRHEAL DISEASES]

Pathophysiology of salmonellosis

• Nausea

• Vomiting

• Diarrhea

• Abdominal cramps occurring 12-72 hours after ingestion

[ENTERIC/DIARRHEAL DISEASES]

S/S of salmonellosis

• Correct hydration via oral rehydration solutions or IV fluids

• Monitor electrolytes (especially Potassium, which is lost in diarrhea)

[ENTERIC/DIARRHEAL DISEASES]

Nursing care for salmonellosis

Norovirus

[ENTERIC/DIARRHEAL DISEASES]

• Highly contagious virus causing sudden onset of acute gastroenteritis (often called “stomach flu”)

• Etiology: Fecal-oral route; notorious for outbreaks on cruise ships and in long-term care facilities

• Strict contact precautions (the virus is highly resistant to many disinfectants)

• Focus is purely supportive: replacing fluids and preventing hypovolemic shock in vulnerable populations

[ENTERIC/DIARRHEAL DISEASES]

Nursing focus for norovirus

Syphilis

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

Etiology: Caused by the spirochete Treponema pallidum

Treponema pallidum

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

What bacterium causes syphilis?

Primary

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

PATHO/STAGE OF SYPHILIS:

Painless ulcer called a Chancre at the site of infection

Secondary

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

PATHO/STAGE OF SYPHILIS:

Widespread maculopapular rash (classically involving palms of hands and soles of feet), generalized lymphadenopathy

Tertiary

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

PATHO/STAGE OF SYPHILIS:

Neurosyphilis, cardiovascular damage, gummas (soft tumor-like growths)

Penicillin G

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

Medical management for syphilis (for all stages)

Educate on safe sex practices and the necessity of testing all sexual partners

[SEXUALLY TRANSMITTED INFECTIONS/STIs]

Nursing interventions for syphilis