Infectious & Communicable Disorders — Core Concepts

The infectious and communicable disorders are about spotting patterns fast: typical rash, route of transmission, correct isolation, and what the nurse does first.

🛡️ Safety Anchors (Infectious)

• Hand hygiene is always #1 – if they ask “priority to prevent infection,” answer is almost always handwashing.

• Match isolation to transmission

  • Airborne: TB, measles, varicella

  • Droplet: scarlet fever, meningococcal meningitis, pertussis, influenza

  • Contact: scabies, wound infections, some GI bugs

• Immunocompromised = low threshold to report any change (cough, SOB, temp, confusion).

• Dog bites / rabies risk → immediate, thorough running water + soap irrigation, then eval for rabies PEP & tetanus.

• Needlesticks = Hep B risk (especially hollow-bore after blood draw).

• Neuro + fever + headache + nuchal rigidity → think meningitis / ↑ICP → protect brain, start droplet, notify provider.

🧩 Clinical Judgment Chain (Infectious):Recognize risk/early signs → identify likely disease & mode of transmission → choose correct isolation → support organ systems (resp, neuro, renal) → prevent spread & complications (education, vaccination, prophylaxis).

👶 Childhood Exanthems & Vaccine-Preventable Viral Diseases

Disorder	Pathophysiology / Type	Incubation & Transmission	Key Clinical Features	Diagnostics	Isolation / Infection Control	Priority Nursing Care / Exam Pearls
Measles (Rubeola)	Paramyxovirus; acute systemic viral exanthem	Incubation ~10–12 days; rash ~14 days. Airborne spread via respiratory droplets/nuclei.	High fever, 3 C’s (cough, coryza, conjunctivitis); Koplik spots on buccal mucosa; red-brown maculopapular rash starting at hairline → down body.	Clinical + exposure; serology (IgM) if needed.	Airborne precautions until 4 days after rash starts; negative-pressure room.	Vitamin A, antipyretics, hydration, darkened room for photophobia. Watch for otitis media, pneumonia, encephalitis. Vaccination is key prevention.
German Measles (Rubella)	Rubella virus; generally mild viral exanthem	Incubation 14–21 days; droplet spread.	Mild fever, tender postauricular and suboccipital nodes; fine pink rash starting face → trunk; arthralgia in older pts; often mild.	Serology (rubella IgM/IgG).	Droplet isolation.	Avoid exposure to pregnant women (congenital rubella). Supportive care, rest. Vaccination (MMR) = prevention.
Roseola Infantum (Exanthem Subitum)	HHV-6; infant viral infection	Incubation ~5–15 days; likely saliva/respiratory.	High fever for 3–5 days (risk febrile seizure) in well-appearing infant → fever abruptly falls → maculopapular rash starting trunk → extremities.	Clinical, typical age 6–24 months.	Standard precautions.	Focus on fever control & seizure prevention, hydration, parental reassurance. Self-limiting.
Chickenpox (Varicella)	Primary infection with Varicella-zoster virus	Incubation 10–21 days; airborne + direct contact with vesicles.	Fever, malaise, pruritic vesicular rash in crops: macules → papules → vesicles → crusts, lesions in different stages at once.	Clinical; PCR if needed.	Airborne + contact until all lesions crusted.	Nail trimming, mittens, oatmeal baths, calamine, loose clothing. Monitor for secondary skin infection & pneumonia. Vaccine prevents severe disease.
Shingles (Herpes Zoster)	Reactivation of latent VZV in dorsal root ganglia	Reactivation years after chickenpox; virus from lesions can cause varicella in nonimmune exposed persons (direct contact).	Prodromal pain/tingling → unilateral, dermatomal band of grouped vesicles on erythematous base; burning pain; possible postherpetic neuralgia.	Clinical diagnosis.	Contact; if disseminated or in immunocompromised, airborne + contact.	Pain control (analgesics, sometimes antivirals), protect lesions, keep away from pregnant, newborns, immunocompromised non-immune people.
Scarlet Fever	Toxin-mediated illness from Group A β-hemolytic Streptococcus	Incubation usually 2–4 days; droplet spread from pharyngitis.	Fever, sore throat, “sandpaper” rash, Pastia’s lines; strawberry tongue; rash in axillae/groin, trunk.	Throat culture, rapid strep test.	Droplet isolation.	Full course of antibiotics (usually penicillin); monitor for rheumatic fever & glomerulonephritis; teach hygiene and not to share utensils.
Poliomyelitis	Poliovirus (enterovirus), neurotropic	Incubation 7–21 days; fecal–oral and oral–oral transmission.	Mostly asymptomatic; some with aseptic meningitis; a few develop asymmetric flaccid paralysis; no sensory loss.	PCR of stool/throat; CSF analysis.	Standard precautions; enhanced contact in outbreaks.	Vaccine-preventable; in acute phase support airway, prevent contractures, PT/rehab if paralysis develops.

😷 Major Bacterial Respiratory & Neuro Infections

Disorder	Pathophysiology / Type	Incubation & Transmission	Key Clinical Features	Diagnostics	Isolation / Infection Control	Priority Nursing Care / Exam Pearls
Pertussis (Whooping Cough)	Bordetella pertussis; toxin-mediated airway inflammation	Incubation 7–10 days (up to 21); droplet spread.	Catarrhal stage: mild URI, very contagious. Spasmodic stage: paroxysmal cough, inspiratory “whoop,” post-tussive vomiting. Convalescent: gradual recovery.	Nasopharyngeal swab PCR/culture.	Droplet precautions.	Maintain droplet isolation; suction PRN; avoid smoke/dust; small frequent feeds; monitor for apnea in infants. Emphasize DTaP/Tdap vaccination. Post-discharge, avoid crowds until cleared.
Diphtheria	Corynebacterium diphtheriae exotoxin causing local necrosis & systemic effects	Incubation 2–5 days (1–10); droplet spread.	Sore throat, low-grade fever, thick gray pseudomembrane in pharynx that may bleed/obstruct airway; “bull neck” (cervical lymphadenopathy).	Throat culture, PCR.	Droplet precautions.	Airway is the priority. Bed rest, antitoxin + antibiotics, emergency airway equipment ready; monitor for myocarditis and neuropathy.
Tetanus	Neurotoxin from Clostridium tetani blocking inhibitory neurotransmitters	Incubation 3–21 days (avg ~8); contamination of deep/dirty wounds with spores. Not person-to-person.	Trismus (lockjaw), risus sardonicus, generalized muscle rigidity and painful spasms, sometimes opisthotonos.	Clinical; history of wound; no specific lab.	Standard precautions.	Reduce stimuli (lights, noise), airway support, muscle relaxants/benzodiazepines, wound debridement, tetanus immune globulin + vaccine. Lockjaw/trismus is classic exam clue.
Bacterial Meningitis (general)	Bacterial infection of meninges/CSF → inflammation & ↑ICP	Incubation: N. meningitidis 2–10 days; S. pneumoniae ~1–3 days; usually droplet spread.	Fever, severe headache, nuchal rigidity, photophobia, vomiting, altered LOC; Kernig and Brudzinski positive; possible seizures.	Lumbar puncture (cloudy CSF, ↑protein, ↓glucose), blood cultures.	Droplet until 24 hrs on effective antibiotics.	First: institute droplet precautions. Then prompt IV antibiotics, neuro checks, manage ↑ICP (HOB 30°, avoid hip flexion), seizure precautions.
Meningococcal Meningitis	Neisseria meningitidis; can cause sepsis	Incubation 2–10 days; droplet via respiratory secretions.	Above meningitis signs plus characteristic petechial or purpuric rash, rapid deterioration, possible shock.	Same LP findings; blood cultures; sometimes skin lesion cultures.	Droplet; mask for staff/visitors.	Give antibiotics ASAP; monitor for septic shock, DIC; prophylaxis for close contacts. Question about 9-month-old suspected case → instituting droplet precaution is priority.
Viral Meningitis	Often enteroviruses; less severe than bacterial	Incubation 3–7 days; fecal–oral or respiratory.	Headache, fever, neck stiffness, photophobia, but typically milder course and better prognosis.	LP: clear CSF, normal glucose, mildly ↑protein, lymphocytic predominance.	Standard or droplet per policy.	Supportive: analgesics for headache, antipyretics, fluids. Teach that full recovery is expected in most cases; main role is symptom control and monitoring.
Pneumonia (Bacterial)	Infection of alveoli/terminal airways → consolidation	Incubation varies (days); droplet & aspiration routes.	Fever, chills, productive cough, dyspnea, pleuritic chest pain, crackles, ↓SpO₂; in elderly may present with confusion.	Chest x-ray, sputum culture, CBC.	Droplet + standard.	Antibiotics as ordered, oxygen, incentive spirometry, turn-cough-deep-breathe, early ambulation, hydration. High-risk: older adults, diabetics, CKD patients.

🦟 Vector-Borne & Re-Emerging Infections

Disorder	Pathophysiology / Type	Incubation & Transmission	Key Clinical Features	Diagnostics	Isolation / Infection Control	Priority Nursing Care / Exam Pearls
Japanese Encephalitis Virus (JEV)	Arbovirus causing brain inflammation	Incubation 5–15 days; mosquito-borne (Culex).	Many asymptomatic; symptomatic: fever, headache, vomiting, altered sensorium, seizures, focal neuro deficits.	Serology, CSF, imaging where available.	Standard precautions; vector control.	Vaccine in endemic areas; mosquito nets, repellents; if ill, support airway, seizure control, ICP management.
Chikungunya Virus	Alphavirus causing febrile polyarthralgia	Incubation 2–4 days (1–12); mosquito-borne (Aedes).	Sudden high fever, severe joint pain, rash, headache, myalgia; may have prolonged joint pains.	Serology, PCR (epidemiologic).	Standard; vector control.	Symptom control (analgesics, fluids), rest; differentiate from dengue (bleeding, low platelets).
Zika Virus	Flavivirus with neurotropic effects in fetus	Incubation 3–14 days; mosquito-borne (Aedes), sexual, vertical.	Often mild: low-grade fever, maculopapular rash, conjunctivitis, arthralgia; many asymptomatic.	Serology/PCR where available.	Standard; vector control; sexual precautions.	Educate women of childbearing age about pregnancy risk (microcephaly). Avoid travel to outbreak areas in pregnancy.
Ebola Virus Disease	Filovirus causing severe hemorrhagic fever	Incubation 2–21 days; contact with infected blood/body fluids; NOT mosquito-borne (this is the exam’s “except”).	High fever, severe weakness, diarrhea, vomiting; later hemorrhage, shock, multi-organ failure.	PCR, antigen tests.	Strict isolation: contact + droplet, sometimes airborne-level PPE.	Aggressive fluid/electrolyte support, strict PPE, support BP and organ function. Public health reporting critical.

🪳 Parasitic & Infestation Disorders

Disorder	Pathophysiology / Type	Incubation & Transmission	Key Clinical Features	Diagnostics	Isolation / Infection Control	Priority Nursing Care / Exam Pearls
Pinworms (Enterobiasis)	Intestinal nematode (Enterobius vermicularis)	Incubation ~2–6 weeks; fecal–oral via contaminated hands, bedding, clothing, dust.	Nocturnal perianal itching, restless sleep; sometimes irritability or bed-wetting.	Cellophane tape test on perianal skin early morning before bathing or toileting (not at bedtime).	Standard precautions; environmental cleaning.	Treat child and close contacts with antihelminthic meds; wash linens in hot water; trim nails; emphasize handwashing. Correct exam note: tape test best in the morning, not “evening before bedtime.”
Scabies	Infestation with Sarcoptes scabiei mites in stratum corneum	Incubation 2–6 weeks first exposure, 1–4 days reinfestation; spread via prolonged skin-to-skin contact, shared bedding.	Intense pruritus worse at night; thin, wavy burrows on finger webs, wrists, waistline, axillae; sometimes vesicles/papules.	Clinical exam; skin scraping if needed.	Contact precautions: gown + gloves; bag/clean linens.	Apply permethrin cream from neck down (repeat per protocol), treat household contacts. Wash clothes/linens in hot water & dry hot. Exam: PPE usually gown and gloves for direct care of lesions.

🩸 Blood / Body-Fluid Viral Infections & HIV

Disorder	Pathophysiology / Type	Incubation & Transmission	Key Clinical Features	Diagnostics	Isolation / Infection Control	Priority Nursing Care / Exam Pearls
Hepatitis A	Acute viral hepatitis, usually self-limited; no chronic carrier state	Incubation 15–50 days (avg ~28); fecal–oral (contaminated food/water), close contact; can be transmitted by certain sexual practices (oral–anal).	Flu-like prodrome, anorexia, nausea, RUQ pain, jaundice, dark urine, pruritus. Usually resolves completely.	Anti-HAV IgM (acute), LFTs.	Standard precautions; enteric precautions if diarrhea.	Vaccine available. Emphasize hand hygiene, safe food/water, especially in outbreaks/travel. Not typically associated with chronic disease like Hep B/C.
Hepatitis B	DNA hepadnavirus; can become chronic, leading to cirrhosis and hepatocellular carcinoma	Incubation 45–160 days (avg ~90); blood and body fluids: unprotected sex, perinatal, needlestick, shared needles.	Acute: fatigue, anorexia, jaundice, RUQ pain. Chronic: often asymptomatic until advanced liver disease.	HBsAg, HBV DNA, LFTs.	Standard precautions; safe injection practices.	Highest occupational risk: needlestick with needle after blood extraction. Reused syringes strongly support HBV transmission (exam statement). Vaccination for health workers; teach condom use and no sharing of needles.
HIV/AIDS	Retrovirus infecting CD4 T cells → immune deficiency	“Window period” for antibodies ~2–12 weeks; transmission via sexual contact, blood, perinatal, and contaminated needles. Not by casual contact, kissing (unless blood), sneezing.	Acute flu-like illness, then asymptomatic phase; later opportunistic infections, weight loss, malignancies.	HIV antigen/antibody tests, viral load, CD4 count.	Standard precautions; safe sex and needle practices.	RA 11166 (Philippine HIV & AIDS Policy Act): promotes multi-agency health education on HIV prevention & safe practices; protects rights & confidentiality; allows wider access to counselling/testing. High-risk group from exam: gay, bisexual, and other men who have sex with men. Emphasize condoms, testing, treatment adherence.

🌬️ Core Respiratory / Zoonotic: TB, Influenza, Rabies

Disorder	Pathophysiology / Type	Incubation & Transmission	Key Clinical Features	Diagnostics	Isolation / Infection Control	Priority Nursing Care / Exam Pearls
Tuberculosis (TB)	Mycobacterium tuberculosis infection causing granulomatous disease, usually lungs	Exposure → latent infection; 2–12 weeks to convert skin test; airborne spread via droplet nuclei.	Chronic cough (sometimes hemoptysis), night sweats, weight loss, low-grade fever, fatigue; can be asymptomatic in latent TB.	Mantoux test (PPD); if positive → chest X-ray to determine lesions; sputum AFB smear/culture or NAAT.	Airborne isolation for active pulmonary TB (N95, negative pressure).	Teach long-term multi-drug regimen; monitor adherence and side effects (e.g., INH, rifampin). Educate about covering mouth, avoiding crowded/poorly ventilated spaces. Exam clue: positive Mantoux → chest X-ray to determine extent.
Influenza	Acute viral infection of upper & lower respiratory tract	Incubation 1–4 days (avg 2); droplet and contact transmission.	Sudden onset fever, chills, myalgia, headache, malaise, sore throat, dry cough. Elderly may show confusion or decline.	Usually clinical; rapid flu tests available.	Droplet + standard precautions.	Annual vaccination especially for older adults and those with diabetes, kidney/heart disease (highest risk for severe outcomes). Symptomatic care, monitor for secondary bacterial pneumonia.
Rabies	Lyssavirus infection of CNS, almost universally fatal once symptomatic	Incubation typically 1–3 months (can vary from days to years); saliva of infected animals via bites or mucous membrane exposure.	Prodrome: fever, malaise, paresthesia at bite site. Excitement stage: agitation, anxiety, hypersalivation, hydrophobia (fear of water), aerophobia; painful spasms of pharyngeal muscles when trying to swallow or even seeing water. Paralytic phase: flaccid paralysis → coma → death.	Mostly clinical history; tests in specialized labs.	Standard precautions; public health reporting.	First aid for dog bite: wash/rinse wound thoroughly with running water and soap, allow slight bleeding; avoid tight closure; then urgent medical assessment for rabies PEP and tetanus. Hydrophobia etiology (exam): severe and painful throat spasms when the patient attempts to swallow or even view liquids. Remind that virus is in saliva, not just blood/skin/claws.

🧠 Quick Checks (Retrieval)

Try to answer before peeking:

1. Which two diseases above absolutely require airborne precautions?

2. What is the first nursing priority intervention for a newly suspected meningococcal meningitis case in a 9-month-old?

3. Pinworm diagnosis: when is the best time to perform the cellophane tape test?

4. In the exam, which re-emerging disease is NOT mosquito-borne: Japanese encephalitis, Chikungunya, Zika, or Ebola?

5. What is the highest-risk route for acquiring Hepatitis B for healthcare workers in the exam scenario?

6. After a positive Mantoux (TB) test, what diagnostic is ordered next and why?

7. What classic sign distinguishes scarlet fever from other rashes?

8. Hydrophobia in rabies is caused by spasms of which area when attempting to swallow or see liquids?

✅ Answers (peek):

1. Measles (rubeola) and active pulmonary TB (and varicella).

2. Institute droplet precautions immediately, then prepare for antibiotics/LP.

3. Early morning before washing or using the toilet, not in the evening.

4. Ebola virus is not mosquito-borne.

5. Needlestick with a needle after blood extraction from a Hep B–infected patient.

6. Chest X-ray → to determine presence/extent of lung lesions and active disease.

7. A “sandpaper-like” rash with strawberry tongue (plus strep throat).

8. Severe and painful throat (pharyngeal) spasms when attempting to swallow or even just view liquids.

✨ Practice Pearls

• “Correct isolation + correct route of transmission = half the exam done.”

• Fever + neuro signs → think meningitis / ↑ICP until ruled out.

• Any question about “most important action to prevent infection” → handwashing almost always.

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