When to intubate in GCS?

GCS ≤ 8 requires intubation for airway protection. The patient cannot protect their own airway at this level of consciousness. Motor score is the most prognostically important component.

What is the best initial fluid for sepsis resuscitation?

Lactated Ringer's (LR) is the preferred resuscitation fluid. The SMART trial (2018) showed balanced crystalloids reduced death, new renal failure, and persistent renal dysfunction compared to normal saline.

When to start vasopressors in septic shock?

Start norepinephrine (first-line vasopressor) if MAP remains < 65 mmHg after initial 30 mL/kg crystalloid resuscitation, or earlier if patient is profoundly hypotensive. Do not delay pressors to complete full fluid resuscitation.

Why can serum uric acid be normal during acute gout?

During acute inflammation, IL-6 increases renal urate excretion and redistributes urate from plasma to tissues. Up to 40% of acute gout flares have normal serum uric acid. Joint aspiration with polarized microscopy is needed for definitive diagnosis.

How do you distinguish lupus flare from infection in SLE?

Key clues: CRP is low/normal in flare but elevated in infection. Complement (C3/C4) drops in flare but is normal/elevated in infection. Procalcitonin is elevated in bacterial infection but normal in flare. Anti-dsDNA rises in flare, stable in infection.

What is the difference between DKA and HHS?

DKA features acidosis (pH 600), hyperosmolality (> 320), and minimal ketosis -typically in Type 2 DM. DKA requires insulin drip; HHS requires aggressive fluid resuscitation first.

When to give tPA in acute ischemic stroke?

IV alteplase (tPA) can be given within 4.5 hours of last known well time in eligible patients. CT head must rule out hemorrhage first. For large vessel occlusion, mechanical thrombectomy can be performed up to 24 hours with favorable imaging.

What antibiotics for community-acquired pneumonia?

Inpatient non-ICU: ceftriaxone + azithromycin. ICU: ceftriaxone + azithromycin (add vancomycin if MRSA risk). Outpatient healthy: amoxicillin. Outpatient with comorbidities: augmentin + azithromycin or respiratory fluoroquinolone. Duration: 5 days if clinically stable for 48 hours.

How to interpret iron studies?

Iron deficiency: low ferritin (< 30), high TIBC, low iron, low transferrin saturation (< 20%). Anemia of chronic disease: normal/high ferritin (acute phase reactant), low TIBC, low iron. A ferritin of 50-100 in an inflamed patient may still represent iron deficiency.

What is the correction rate for hyponatremia?

Correct sodium no more than 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome (ODS). For symptomatic severe hyponatremia with seizures, give 3% hypertonic saline 100-150 mL bolus over 10-20 minutes. If overcorrected, use D5W + DDAVP rescue protocol.

When to start antibiotics in meningitis?

Within 30-60 minutes. Do NOT delay antibiotics for LP or CT. Draw blood cultures, start empiric antibiotics (vancomycin + ceftriaxone ± ampicillin if > 50 or immunocompromised), then perform LP when possible. Dexamethasone should be given before or with the first antibiotic dose.

DOACs vs warfarin in antiphospholipid syndrome?

DOACs are contraindicated in APS. The TRAPS trial (2018) showed rivaroxaban was inferior to warfarin with more thrombotic events in triple-positive APS patients. Warfarin with INR target 2-3 is the standard for APS, indefinitely.

How to manage scleroderma renal crisis?

ACE inhibitors (captopril) are life-saving -start immediately and titrate aggressively. Do NOT hold for rising creatinine. Steroids > 15 mg prednisone per day precipitate scleroderma renal crisis. ARBs are NOT a substitute -evidence is only for ACEi.

What are the 4 pillars of heart failure treatment?

Guideline-directed medical therapy (GDMT) for HFrEF: (1) ARNI or ACEi/ARB, (2) beta-blocker (carvedilol, metoprolol succinate, or bisoprolol), (3) MRA (spironolactone or eplerenone), (4) SGLT2 inhibitor (dapagliflozin or empagliflozin). All four should be initiated and titrated to target doses.

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EMERGINGHIGH MORTALITYInfectious DiseasePulmonary

Hantavirus (HPS & HFRS)

Rodent-borne RNA virus causing two distinct syndromes: Hantavirus Pulmonary Syndrome (HPS) in the Americas (cardiopulmonary phenotype, 35–50% mortality) and Hemorrhagic Fever with Renal Syndrome (HFRS) in Eurasia (renal-dominant phenotype). Treatment is supportive; VA-ECMO is the only intervention shown to dramatically improve survival in HPS.

🔍 Overview

🚨 Active 2026 Outbreak (as of May 2026): An Andes virus outbreak on the cruise ship M/V Hondius (departed Ushuaia, Argentina, March 20, 2026 → Cabo Verde → Canary Islands). As of May 6, 2026: 5 confirmed + 3 suspected cases, 3 deaths (Dutch couple, German national). Symptoms onset April 6–28, 2026: fever, GI symptoms, rapid pneumonia → ARDS → shock. Three US passengers under monitoring (2 Georgia, 1 Arizona, all asymptomatic at last update).

Why this matters clinically: Andes is the only hantavirus with documented person-to-person transmission (respiratory droplets in close-contact settings). Maintain droplet/airborne precautions for any suspected case with recent South America travel or cruise-ship exposure. Sources: WHO Disease Outbreak News (DON599, May 2026); CDC Newsroom; CIDRAP.

Definition & Two Syndromes

Hantaviruses are single-stranded RNA viruses (Bunyavirales order, Hantaviridae family) carried by specific rodent reservoirs. Each virus species causes distinct disease depending on the host rodent and geography.

	HPS (Hantavirus Pulmonary Syndrome)	HFRS (Hemorrhagic Fever with Renal Syndrome)
Region	Americas (New World hantaviruses)	Eurasia (Old World hantaviruses)
Major viruses	Sin Nombre virus (US, dominant), Andes virus (S. America), Bayou, Black Creek Canal, Choclo	Hantaan (severe, China/Korea), Dobrava (Balkans), Seoul (worldwide), Puumala (mild, Scandinavia/Europe)
Reservoir rodent	Deer mouse (Peromyscus maniculatus), cotton rat, rice rat (US); long-tailed pygmy rice rat (Andes virus, S. America)	Striped field mouse (Hantaan), bank vole (Puumala), brown rat (Seoul)
Phenotype	Cardiopulmonary: non-cardiogenic pulmonary edema, refractory shock	Renal + hemorrhagic: AKI, retroperitoneal/GI bleeding, capillary leak
Mortality	35–50% (Sin Nombre), ~40% (Andes)	0.1% (Puumala) to 10–15% (Hantaan, Dobrava)
Person-to-person?	YES for Andes virus only (respiratory droplets, close-contact settings, household and healthcare). NO for Sin Nombre or other US strains.	NO for any HFRS-causing virus.

Epidemiology (HPS in the US)

~30–40 US cases per year, ~890 cumulative cases since CDC surveillance began in 1993, ~35% case-fatality rate.
~95% of cases west of the Mississippi. Highest incidence in Four Corners region (NM, AZ, CO, UT) where deer mouse populations are densest.
Recent US notable cases: Gene Hackman's wife Betsy Arakawa (Santa Fe, NM, February 2025); Mammoth Lakes, CA cluster (early–mid 2025).
Risk activities: cleaning out cabins, sheds, barns, garages with rodent infestation; camping in rodent-prone areas; rural occupations (farming, forestry, military field exercises).
2026 cruise-ship cluster (Andes virus, M/V Hondius) is unusual: ship-board transmission with documented person-to-person spread is a new pattern outside South American endemic regions.

Pathophysiology

Hantavirus infects vascular endothelium via β3-integrin receptor, especially pulmonary capillary endothelium (HPS) or renal/glomerular endothelium (HFRS).
Viral replication triggers a cytokine storm (IL-6, TNF-α, IFN-γ) and immune-mediated endothelial injury → capillary leak.
HPS: capillary leak in pulmonary vasculature → non-cardiogenic pulmonary edema and ARDS-like picture; superimposed myocardial depression → cardiogenic component → refractory shock.
HFRS: capillary leak in renal vasculature + retroperitoneum → AKI (proteinuria, hematuria, oliguria) + hemorrhagic phenomena (petechiae, GI/retroperitoneal bleeds, conjunctival hemorrhage).
Why mortality is so high in HPS: the cardiopulmonary phase progresses over hours, often before diagnosis is made. Capillary leak resists fluid resuscitation (more fluid worsens pulmonary edema). The myocardial depression component reduces cardiac output independent of preload.

Clinical Phases of HPS

Phase	Duration	Features	Why It Matters
1. Prodromal	3–6 days	Fever, severe myalgias (especially thighs, hips, lower back), headache, nausea, vomiting, abdominal pain. Looks like flu or gastroenteritis.	Most missed phase. Dry cough or dyspnea is uncommon early. Diagnosis often made retrospectively.
2. Cardiopulmonary	Hours to a few days	Rapid-onset dyspnea, tachypnea, hypoxemia, pulmonary edema, refractory hypotension. CXR: bilateral interstitial → alveolar infiltrates ± pleural effusions. Often progresses to intubation in < 24h.	Lethal phase. Most deaths here. Distinguish from cardiogenic shock by echo (preserved EF). Distinguish from septic shock by lab triad (thrombocytopenia + hemoconcentration + immunoblasts).
3. Diuretic	1–2 days	Rapid resolution of capillary leak: brisk diuresis, restored BP, improving oxygenation.	If patient survives phase 2, recovery can be dramatic. Cautious volume management as fluid mobilizes.
4. Convalescent	Weeks to months	Persistent fatigue, exertional dyspnea, weakness.	Most survivors return to baseline.

Differential Diagnosis (in a patient with prodrome → respiratory failure)

Influenza, COVID-19, RSV, look-alike prodromes; hantavirus has more profound thrombocytopenia, hemoconcentration, and rapid progression to ARDS without typical respiratory prodrome.
Sepsis with ARDS, blood cultures, procalcitonin help; sepsis usually has a clear source.
Leptospirosis, also rodent contact, but causes biphasic illness with renal failure, jaundice, and conjunctival suffusion; treat empirically with doxycycline if exposure overlap.
Plague (pneumonic), rare but possible exposure overlap (rodents/fleas); rapid bacterial pneumonia + sepsis; covered by aminoglycosides or doxycycline.
Q fever, tularemia, similar zoonotic exposures, atypical pneumonia patterns.
Cardiogenic shock, echo with preserved EF rules out in HPS context.

🧪 Workup

Diagnostic Triad in HPS

Three-feature triad that should make you think hantavirus in any patient with prodrome → respiratory failure:

Thrombocytopenia (often < 100K, sometimes < 50K), present in > 90%.
Hemoconcentration (rising hematocrit from capillary leak losing intravascular fluid).
Immunoblasts on peripheral smear (> 10% atypical lymphocytes with abundant basophilic cytoplasm). Hand-counted smear, not flagged by automated CBC.

All three present in > 80% of HPS cases at presentation. Add exposure history (rodents, Four Corners, recent cruise/South America in 2026) → high pretest probability.

Laboratory

CBC with manual differential: thrombocytopenia, hemoconcentration (rising Hct), immunoblasts (atypical lymphocytes > 10%), often left shift.
BMP, Mg, phos: AKI common in HPS (less prominent than HFRS but present), hyperkalemia, lactic acidosis.
LDH, AST, ALT: ↑ from capillary leak / tissue ischemia / mild hepatitis.
Lactate: ↑ from tissue hypoperfusion in shock.
Coags (PT/INR, aPTT, fibrinogen): mild coagulopathy in HPS; more prominent (DIC-like) in HFRS.
Albumin: ↓ from capillary leak.
Troponin, BNP/NT-proBNP: trop often mildly ↑ from myocardial depression; BNP normal-to-low (helps distinguish from cardiogenic edema).
Blood cultures, respiratory viral panel, COVID-19 NAT, urine Legionella/Strep pneumoniae antigens: exclude alternatives.

Hantavirus-Specific Testing

Hantavirus IgM and IgG by ELISA, sensitivity ~95% by the time cardiopulmonary phase begins (IgM positive almost always at admission; paired serology helps if early). Available through state public health labs and CDC.
RT-PCR for viral RNA from blood or tissue, useful in early infection before serology turns positive. CDC and reference labs.
Andes virus-specific testing if exposure history fits (recent South America, M/V Hondius, close contact with confirmed Andes case).
Notify public health immediately on suspicion, hantavirus is reportable in all US states.

Imaging & Bedside Tests

CXR: bilateral interstitial infiltrates (early) → alveolar infiltrates with perihilar predominance and Kerley B lines, ± pleural effusions. Looks like ARDS or cardiogenic edema.
Bedside echo: preserved or only mildly depressed EF (key discriminator from cardiogenic shock). May show small chamber size from preload depletion.
POCUS lung: B-lines bilaterally (non-specific for non-cardiogenic vs cardiogenic edema; combine with echo).
CT chest (if stable enough): bilateral ground-glass and consolidation, perihilar predominant.

🚨 Management

There Is No Specific Antiviral, This Is Supportive ICU Care

HPS kills via refractory shock + ARDS over hours. The interventions that move the needle: early ICU transfer, lung-protective ventilation, judicious fluid restriction (capillary leak resists volume), early vasopressors, and consideration of VA-ECMO at experienced centers, which has improved HPS survival from ~35% to ~50–65% in case series.

Step-by-Step Management

Step	Intervention	Why It Matters
1. Early ICU + isolation	Transfer to ICU at first sign of pulmonary involvement. Droplet + airborne precautions for any suspected Andes virus or undifferentiated case.	Decompensation is rapid (hours). Andes virus has documented person-to-person spread; standard hantavirus species do not, but until species is identified, full precautions are safer.
2. Lung-protective ventilation	Tidal volume 4–6 mL/kg ideal body weight, plateau pressure < 30 cmH₂O, PEEP titrated, FiO₂ to SpO₂ 88–94%. Prone if P/F < 150.	HPS pulmonary edema behaves like ARDS. ARDSnet protocol applies. ARMA, 2000
3. RESTRICT fluids	Avoid liberal crystalloid resuscitation. Target euvolemia or mild dryness. Use albumin in select cases (preserves oncotic pressure during capillary leak).	This is the pitfall. The instinct in shock is to give fluids; in hantavirus the capillary is leaking and more fluid worsens pulmonary edema while not raising BP. Pressors over volume.
4. Early vasopressors	Norepinephrine first-line, titrate to MAP ≥ 65. Add vasopressin 0.03 units/min if escalating. Epinephrine if myocardial component dominant.	Hypotension here is distributive + cardiogenic, not hypovolemic. Pressors restore perfusion without worsening pulmonary edema.
5. Consider VA-ECMO early	Refer to ECMO center if: refractory shock on 2+ pressors, refractory hypoxemia despite proning, cardiac index < 2.2, lactate rising. Do not wait for crash.	The single intervention that has moved HPS mortality from ~35% to ~50–65%. VA-ECMO bridges the patient through the cardiopulmonary phase (typically 3–7 days); diuretic phase begins and patient can be weaned.
6. Inotropic support if EF depressed	Epinephrine drip or milrinone (if SBP allows) for myocardial component.	HPS has a real myocardial depression component (immune-mediated myocarditis-like). Inotropes when EF is reduced.
7. Notify public health + isolate	Reportable disease in all US states. Andes virus exposure history → contact tracing.	Critical for outbreak control, especially Andes virus where person-to-person spread occurs.
8. Avoid corticosteroids for HPS	No proven benefit; may worsen viral replication.	Routine steroids are NOT supported by evidence. Reserve for refractory ARDS per standard ARDS protocols.
9. Ribavirin: NOT for HPS; YES for HFRS	HPS: ribavirin trials negative, do not use. HFRS: IV ribavirin (33 mg/kg load → 16 mg/kg q6h × 4d → 8 mg/kg q8h × 6d) reduces mortality if started within 7 days of onset.	This is a syndrome-specific distinction. Don't reflex ribavirin for HPS; it doesn't work. HFRS is the syndrome where it has documented benefit.
10. Renal support (HFRS >> HPS)	CRRT or HD for AKI with refractory hyperkalemia, volume overload, severe acidosis, or uremia.	HFRS often has prominent AKI requiring temporary dialysis. HPS has milder AKI usually.
11. Investigational	Convalescent plasma (case reports), Andes virus-specific monoclonal antibodies (in development as of 2026).	No standard-of-care role yet. Consider through clinical trial enrollment if available.

Infection Control (Andes Virus / Outbreak Setting)

For confirmed or suspected Andes virus (or any hantavirus pending species ID):

Single-patient room, negative-pressure if airborne procedures planned (intubation, bronchoscopy).
Droplet precautions (mask within 6 ft) + airborne precautions during aerosol-generating procedures (N95, eye protection).
Contact precautions (gown, gloves) for any patient contact.
Healthcare worker monitoring: symptom watch × 6 weeks (Andes virus incubation 7–42 days, typically 14–21).
Household contact tracing if Andes virus.
Sin Nombre virus and other US strains: standard precautions sufficient (no documented person-to-person spread). But until species confirmed, treat as Andes-like.

💊 Medications

Medications Reference

Drug	Dose	Role	Notes
Norepinephrine FIRST-LINE	0.05–1 mcg/kg/min IV	Vasopressor for distributive/mixed shock	Titrate to MAP ≥ 65. Central access preferred. Peripheral OK as bridge.
Vasopressin	0.03 units/min IV (fixed)	Adjunct vasopressor	Add when escalating norepinephrine; spares catecholamine dose.
Epinephrine	0.05–1 mcg/kg/min IV	Inopressor when myocardial depression dominant	Useful when EF depressed and MAP low. Can cause tachyarrhythmias.
Milrinone	0.25–0.75 mcg/kg/min IV (no bolus typically)	Inotrope for myocardial depression with adequate BP	Avoid if hypotensive (vasodilator effect). Useful if cardiogenic component limits ECMO bridge.
Albumin 5%	250–500 mL IV PRN	Volume expander preserving oncotic pressure	Selective use during capillary leak; avoid liberal crystalloid.
Ribavirin HFRS ONLY	IV: 33 mg/kg load → 16 mg/kg q6h × 4d → 8 mg/kg q8h × 6d	Antiviral, HFRS only (NOT HPS)	Most effective if started within 7 days of symptom onset. Side effects: hemolytic anemia, teratogenic (FDA category X). Useless in HPS, do not use.
Doxycycline	100 mg PO/IV BID	Empiric coverage for leptospirosis until ruled out	If exposure overlap with leptospirosis (rodent + freshwater), cover empirically while awaiting hantavirus testing.
Vancomycin + cefepime or pip-tazo	Renal-dose-adjusted	Empiric sepsis/CAP coverage	Until hantavirus confirmed and bacterial sepsis ruled out, cover broadly.

VA-ECMO Criteria (Refer Early)

Refer to ECMO center when one or more present:

Refractory shock requiring norepinephrine > 0.5 mcg/kg/min plus a second pressor
Cardiac index < 2.2 L/min/m² with elevated lactate
Refractory hypoxemia: P/F < 80 despite optimal vent + proning
pH < 7.20 from mixed acidosis, not improving
Echo with EF significantly depressed (< 40%) in the cardiopulmonary phase

Why early: mortality without ECMO in patients meeting these criteria approaches 100%. With ECMO at experienced centers, ~50–65% survive. The diuretic phase typically arrives within 3–7 days of ECMO support.

🛡️ Prevention

Quick answer: Hantavirus is prevented by avoiding aerosolized rodent excreta. The highest-risk activity is sweeping or vacuuming a rodent-infested cabin, garage, or shed. Always wet down with bleach solution first, wear an N95 + gloves + eye protection, and never sweep dry. No vaccine is available in the US. For the 2026 Andes virus cruise outbreak, returning travelers should monitor for fever, severe muscle pain, and dyspnea for 6 weeks (incubation 7–42 days, typically 14–21).

How is hantavirus spread?

Hantaviruses are carried in the saliva, urine, and feces of infected rodents. Humans get infected by inhaling aerosolized virus when contaminated dust is stirred up (sweeping, vacuuming, disturbing nesting material). Less commonly, infection happens through:

Direct rodent contact, bites, scratches, or handling without gloves
Eating food contaminated with rodent excreta
Touching contaminated surfaces, then touching eyes, nose, or mouth
Person-to-person, only Andes virus (respiratory droplets in close-contact household and healthcare settings). All other hantaviruses, including Sin Nombre virus (the dominant US strain), do NOT spread between people.

Key reservoir species in the US: deer mouse (Peromyscus maniculatus) is the primary carrier of Sin Nombre virus, especially in the Four Corners region (New Mexico, Arizona, Colorado, Utah). Cotton rats, rice rats, and white-footed mice carry related strains.

How do I safely clean rodent droppings, urine, and dead rodents?

Never sweep or vacuum dry. This aerosolizes the virus directly into your breathing zone and is the most common cause of hantavirus infection.

CDC step-by-step cleanup method:

Ventilate first. Open all doors and windows for at least 30 minutes before entering. Leave the area while it ventilates. Why: this lets airborne virus particles disperse before you walk in.
Put on protective gear: N95 respirator (or higher), nitrile or rubber gloves, eye protection, long sleeves, closed shoes. A surgical mask is NOT adequate.
Mix a 1:10 bleach solution (1 part household bleach to 9 parts water = 10% bleach) OR an EPA-registered disinfectant labeled for viruses. Pour into a spray bottle.
Spray or pour disinfectant directly onto droppings, urine, and nesting material until thoroughly soaked. Let sit for at least 5 minutes. Why: contact time matters; bleach inactivates the virus on contact but needs the wet exposure.
Wipe up with paper towels or a damp cloth. Do not sweep, vacuum, or use a duster. Place all waste in a sealable plastic bag.
Disinfect the area again after wiping (sprayer or mop with bleach solution).
For dead rodents: spray the carcass and the surrounding area with disinfectant, soak for 5 minutes, place in a plastic bag, double-bag, and dispose in covered trash. Wash any traps with the same bleach solution.
Wash gloves before removing them, then wash hands thoroughly with soap and water for at least 20 seconds.
Wash any contaminated clothing in hot water and detergent.

Heavy infestation warning: If you find a heavily contaminated space (a long-vacant cabin, an attic with extensive nesting, a shed with dozens of droppings), do not clean it yourself. Hire a licensed pest-control service with PAPR (powered air-purifying respirator) capability. The risk of aerosolization in heavy infestations exceeds what an N95 alone protects against.

How do I rodent-proof my home, cabin, or outbuilding?

Hantavirus prevention starts with keeping rodents out of human-occupied spaces. The CDC's "Seal Up, Trap Up, Clean Up" framework:

1. Seal up entry points

Inspect the home exterior for openings 1/4 inch (6 mm) or larger. Mice can squeeze through gaps the size of a dime.
Seal gaps around pipes, utility cables, vents, and dryer outlets with steel wool plus caulk, or hardware cloth (1/4-inch mesh).
Repair gaps in foundations, siding, and door/window frames.
Install door sweeps. Why: most rodent entry happens at ground level under doors.

2. Trap up

Snap traps are preferred over glue traps and live traps. Why: glue traps don't kill quickly and stress the rodent (can promote viral shedding); live traps require handling the animal, which is high-risk.
Bait with peanut butter or oats; place along walls where rodents travel.
Check traps daily. Disinfect traps and rodent carcasses with the cleanup protocol above.

3. Clean up the food and shelter

Store all food (including pet food and birdseed) in rodent-proof metal or thick plastic containers with tight lids. Don't leave pet food bowls out overnight.
Wash dishes, clean counters, and store leftovers promptly.
Remove brush, woodpiles, junk, and abandoned vehicles from within 100 feet of the home. These are nesting sites.
Keep grass mowed short.
Elevate woodpiles and hay bales at least 1 foot off the ground.

How do I open a cabin or seasonal property safely?

Long-vacant cabins, hunting camps, and seasonal homes in the Four Corners region (New Mexico, Arizona, Colorado, Utah) are the highest-risk setting for US hantavirus. Before staying or cleaning:

Approach from outside. Open all doors and windows from outside before entering, then leave the cabin airing out for at least 30 minutes.
Inspect for evidence of rodents from the doorway: droppings, gnawed food packaging, nesting material, urine stains, dead rodents, mouse smell. Heavy evidence = call professionals.
Don and spray. If contamination is light to moderate and you'll clean yourself: N95, gloves, eye protection. Spray all visible droppings and nests with 10% bleach. Let sit 5 minutes.
Wet-wipe everything. Counters, floors, tabletops, the inside of drawers and cabinets. Discard exposed food.
Wash bedding, towels, and any cloth items in hot water before use.
Set traps for next time. Place snap traps along walls before you leave so the next visit starts cleaner.

Camping, hiking, and outdoor recreation

Avoid sleeping on bare ground in known rodent-active areas (mountain meadows, abandoned structures). Use a tent with a floor or hammock.
Don't disturb rodent burrows, dens, or nests.
Store food in rodent-proof containers (sealed bear canisters work, OdorBarrier sacks, or hung at least 12 ft up and 6 ft out from a tree branch).
Camp in clean, dry sites; avoid trash piles or evidence of rodent activity.
Never handle wild rodents, dead or alive.

2026 Andes virus outbreak: traveler precautions

If you traveled on the M/V Hondius cruise (Ushuaia, Argentina → Cabo Verde → Canary Islands, March–April 2026), or had close contact with anyone who did:

Self-monitor for symptoms × 6 weeks from last possible exposure (Andes virus incubation 7–42 days, typically 14–21).
Seek medical care immediately if you develop fever, severe muscle pain (especially thighs and lower back), nausea/vomiting, headache, or shortness of breath. Mention the cruise exposure, this changes diagnostic suspicion and treatment.
Avoid close contact with others if you become ill (Andes virus has documented person-to-person transmission via respiratory droplets, especially in household settings).
Notify your local public health department, hantavirus is reportable in all US states.

For South America travel in 2026 generally: the Andes virus is endemic to Argentina, Chile, Bolivia, and southern Brazil. Avoid abandoned buildings, brush areas, and food contaminated by rodents. Andes virus household clusters have been documented since the 1996 El Bolsón outbreak in Argentina.

Healthcare worker precautions

Setting	Precautions	Rationale
Suspected hantavirus, species unknown	Airborne + droplet + contact. Single-patient negative-pressure room. N95 (or PAPR), eye protection, gown, gloves.	Until species is confirmed, treat as if Andes virus (the only person-to-person transmissible strain). Better to over-protect early.
Confirmed Andes virus	Continue full airborne + droplet + contact precautions. Restrict visitors. Aerosol-generating procedures (intubation, bronchoscopy, suctioning) require full PPE + negative pressure.	Andes virus has documented household and nosocomial spread, including healthcare-worker infections in Argentina and Chile.
Confirmed Sin Nombre or other US strain	Standard precautions sufficient.	No documented person-to-person spread. Rodent-acquired only.
Healthcare worker post-exposure	Symptom monitoring × 6 weeks (Andes incubation 7–42 days). Report immediately if febrile illness develops.	No post-exposure prophylaxis exists. Early recognition is the only mitigation.

What should I do if I think I've been exposed?

Don't panic but don't ignore it. Most exposures don't cause infection; the attack rate after typical exposure is low. But hantavirus has no specific antiviral, so early recognition is critical.
Watch for symptoms over 6 weeks. Most cases present 14–21 days after exposure with fever, severe muscle aches (especially thighs, lower back, hips), headache, nausea, and vomiting. Cough and shortness of breath develop later (the cardiopulmonary phase, often days 4–7 of illness).
Seek emergency care for any of: shortness of breath, chest tightness, hypoxia, or rapid worsening. The cardiopulmonary phase progresses in hours; do NOT wait it out.
Tell the medical team about your exposure history, rodent contact, cabin cleaning, recent South America travel, M/V Hondius cruise, close contact with a confirmed case. This changes diagnostic suspicion and may save your life.
No vaccine is available in the US. Hantaan-virus vaccines are licensed in South Korea and China but not for Andes or Sin Nombre virus.

Frequently Asked Questions

Is hantavirus contagious between people?

Only the Andes virus strain (found in South America and on the M/V Hondius cruise ship in 2026) has documented person-to-person transmission via respiratory droplets in close-contact settings, especially household members and healthcare workers. All other hantaviruses, including Sin Nombre virus (the main US strain), are NOT contagious between people. Standard infection in the US comes from inhaling aerosolized rodent excreta.

How long after exposure do hantavirus symptoms appear?

Incubation is typically 14–21 days but can range from 1 week to 6 weeks (7–42 days). The first phase (prodrome) is fever, severe muscle aches in the thighs/back/hips, headache, nausea, and vomiting, lasting 3–6 days. The dangerous cardiopulmonary phase (cough, shortness of breath, low blood pressure) typically begins around days 4–7 of illness and can progress over hours.

Can you get hantavirus from a mouse bite?

Yes, but it's uncommon. Most US hantavirus cases come from inhaling aerosolized rodent excreta during cleaning or activity in infested spaces. Bites and scratches are a documented but rare route. If bitten by a wild rodent, wash the wound thoroughly, contact your healthcare provider, and monitor for symptoms for 6 weeks.

Can hantavirus be cured?

There is no specific antiviral cure for HPS (the cardiopulmonary form caused by Sin Nombre and Andes viruses). Treatment is supportive ICU care: lung-protective ventilation, vasopressors, and early VA-ECMO referral for severe cases (which improves survival from ~35% to 50–65% at experienced centers). For HFRS (the Eurasian renal-hemorrhagic form), IV ribavirin within 7 days of symptom onset reduces mortality. Ribavirin does not work for HPS.

Is there a hantavirus vaccine?

No vaccine is available in the United States. Inactivated Hantaan-virus vaccines are licensed in South Korea and China for the HFRS strains common there, but no vaccine targets Sin Nombre virus or Andes virus. Prevention relies entirely on rodent control, safe cleaning practices, and avoiding aerosolization.

Where is hantavirus most common in the United States?

~95% of US cases occur west of the Mississippi River, with the highest concentration in the Four Corners region (New Mexico, Arizona, Colorado, Utah) where deer mouse (Peromyscus maniculatus) populations are densest. Notable recent cases include Betsy Arakawa (Gene Hackman's wife, Santa Fe NM, February 2025) and the Mammoth Lakes, California cluster (2025). Total US cases since CDC surveillance began in 1993: ~890, with ~30–40 new cases per year.

What disinfectant kills hantavirus?

A 1:10 bleach solution (10% bleach in water) is the standard CDC recommendation for home cleanup. EPA-registered disinfectants labeled for "viruses" or "general use" are also effective. The key is contact time: spray or pour the disinfectant directly on droppings/urine/nesting material and let sit at least 5 minutes before wiping. Hantavirus is enveloped and is inactivated by bleach, alcohol-based disinfectants, and most commercial cleaners; UV light and drying also reduce viability over hours to days.

📋 On Rounds

On Rounds

📋 Sample Presentation

"Mr. Velasquez is a 42-year-old man with no significant PMH presenting with 4 days of fever, severe thigh and back myalgias, headache, and nausea, who developed acute dyspnea and hypoxia in the past 12 hours. He spent the prior weekend cleaning out his uncle's cabin in northern New Mexico, with visible mouse droppings. On arrival: SpO₂ 82% on RA, HR 130, BP 82/48. CXR shows bilateral perihilar interstitial infiltrates without cardiomegaly. Labs: platelets 62, Hct 52% (baseline 42), WBC 14 with 12% atypical lymphocytes (immunoblasts on smear), LDH 580, lactate 4.8, troponin mildly elevated, BNP 80. Bedside echo: preserved EF, small chamber size. We made the clinical diagnosis of Hantavirus Pulmonary Syndrome (most likely Sin Nombre virus given Four Corners exposure), sent hantavirus IgM/IgG and RT-PCR, and notified state public health. He was intubated for ARDS, started on lung-protective ventilation, norepinephrine for shock, and is being transferred to our ECMO center. Standard precautions only since US strains are not person-to-person transmitted."

Pimp Questions

What's the diagnostic triad for HPS on routine labs?

Thrombocytopenia + hemoconcentration + immunoblasts on peripheral smear, present in > 80% at presentation. Thrombocytopenia is often < 100K. Hemoconcentration (rising Hct) reflects intravascular fluid loss into tissues from capillary leak. Immunoblasts are atypical lymphocytes > 10% on hand-counted smear (auto-CBC misses them). Add the exposure history (rodents, Four Corners, recent South America/cruise in 2026) and pretest probability is high.

Why is fluid resuscitation a pitfall in HPS?

The capillary endothelium is leaking, so administered crystalloid moves into the alveolar space and worsens pulmonary edema without raising BP. The shock is distributive + cardiogenic, not hypovolemic. Use vasopressors (norepinephrine, vasopressin) rather than volume. Albumin selectively can preserve oncotic pressure. This is opposite to standard sepsis bundles, where 30 mL/kg is the reflex.

When does ribavirin work in hantavirus?

HFRS only, and only if started within 7 days of symptom onset. IV ribavirin (33 mg/kg load → 16 mg/kg q6h × 4d → 8 mg/kg q8h × 6d) reduces mortality in HFRS. Ribavirin does NOT work in HPS, multiple trials in the Americas were negative. Don't reflex ribavirin in HPS; treatment is supportive ICU care + early VA-ECMO consideration.

Which hantavirus strain has person-to-person transmission?

Andes virus is the only hantavirus with documented person-to-person transmission (respiratory droplets in close-contact household and healthcare settings). This is clinically relevant in 2026 because of the M/V Hondius cruise-ship outbreak (Andes virus, 5 confirmed + 3 suspected cases, 3 deaths as of May 6, 2026). All other hantaviruses, including Sin Nombre virus (the dominant US strain), are spread only via rodent excreta aerosolization. For undifferentiated hantavirus suspicion, use droplet + airborne precautions until species is identified.

How does VA-ECMO improve mortality in HPS?

VA-ECMO bridges the patient through the cardiopulmonary phase (typically 3–7 days), supporting cardiac output and oxygenation while the immune-mediated capillary leak and myocardial depression resolve. The diuretic phase then arrives and the patient can be weaned. Case series at experienced centers report HPS survival of 50–65% with ECMO vs 35% without. Refer early when patient meets criteria (refractory shock on 2+ pressors, P/F < 80, EF < 40%, lactate rising), do not wait for cardiac arrest.

Clinical Examples

📋 Case 1, Classic Sin Nombre HPS (US)

Patient: 42M, no PMH, cleaned out uncle's cabin in N. New Mexico last weekend (visible rodent droppings). 4 days of fever, severe thigh/back myalgia, GI symptoms; today acute dyspnea + hypoxia.

Key findings: SpO₂ 82% RA, BP 82/48, HR 130. Plt 62, Hct 52% (baseline 42), 12% immunoblasts on smear, LDH 580, lactate 4.8. CXR: bilateral perihilar interstitial infiltrates. Echo: preserved EF.

Management:

ICU + intubation + ARDSnet ventilation
Norepinephrine + vasopressin (avoid liberal fluids, capillary leak)
Hantavirus IgM/IgG + RT-PCR sent; state public health notified
Empiric doxycycline (lepto coverage) + vanc/cefepime until cultures back
ECMO consult, transferred to ECMO center given P/F 70 and lactate rising
Standard precautions (US strain, no person-to-person spread)

Teaching point: Four Corners + cabin cleaning + prodrome with severe myalgias + thrombocytopenia + immunoblasts = HPS until proven otherwise. Treatment is supportive ICU + early ECMO referral.

📋 Case 2, Andes Virus from 2026 Cruise Ship

Patient: 56F, 14 days post-disembarkation from M/V Hondius cruise (Ushuaia → Cabo Verde, March–April 2026). 5 days of fever and GI symptoms, now acute dyspnea.

Key findings: SpO₂ 86% RA, plt 48, Hct rising, immunoblasts present, lactate 5.2. CXR: bilateral infiltrates. Wife (close household contact during voyage) also developed mild fever.

Management:

Airborne + droplet + contact precautions immediately (Andes virus suspected)
Single-patient negative-pressure room; N95 + eye protection for staff
Andes virus-specific RT-PCR (CDC); standard hantavirus serology
State + CDC + WHO public health notification (international outbreak)
Wife isolated and monitored for symptom development × 6 weeks
Supportive care as in Case 1; early ECMO referral

Teaching point: 2026 outbreak alert. Recent South America travel or M/V Hondius itinerary + hantavirus syndrome → Andes virus suspect → airborne/droplet precautions + contact tracing of close contacts. Person-to-person spread is unique to Andes among hantaviruses.

📋 Case 3, HFRS (Eurasian Hantavirus)

Patient: 34M military service member, recently returned from field exercise in South Korea. Presents with 5 days of fever, severe lumbar/flank pain, and now oliguria.

Key findings: Cr 4.2 (baseline 0.9), proteinuria 3+, hematuria, plt 75, conjunctival hemorrhages on exam, mild facial flushing. CXR clear. BP 88/52.

Management:

ICU monitoring; aggressive renal support (CRRT/HD as needed for AKI/hyperK)
IV ribavirin 33 mg/kg load → 16 mg/kg q6h × 4d → 8 mg/kg q8h × 6d (HFRS, day 5 of symptoms, within 7-day window)
Hantaan / Dobrava / Seoul serology + RT-PCR
Watch for hemorrhagic complications (retroperitoneal/GI bleed)
Vasopressors as needed; cautious fluids

Teaching point: HFRS is the Eurasian phenotype: renal-dominant + hemorrhagic. Ribavirin works here if started within 7 days of onset, unlike HPS where it is ineffective. Travel history (Korea, China, Russia, Balkans, Scandinavia) plus AKI + thrombocytopenia + hemorrhagic features = consider HFRS.

🎯 Summary

At a Glance

Two Syndromes

HPS (Americas, cardiopulmonary, 35–50% mortality) vs HFRS (Eurasia, renal-hemorrhagic, 0.1–15% mortality).

2026 Outbreak

Andes virus on M/V Hondius cruise (Ushuaia → Cabo Verde → Canary Islands, March–April 2026). 5 confirmed + 3 suspected, 3 deaths as of May 6, 2026. Person-to-person spread documented.

US Epidemiology

~30–40 cases/year, ~95% west of Mississippi, Four Corners predominant. ~890 cumulative cases since 1993. Sin Nombre virus dominant.

Transmission

Aerosolized rodent excreta. Person-to-person ONLY for Andes virus (respiratory droplets, close contact).

Diagnostic Triad

Thrombocytopenia + hemoconcentration + immunoblasts on smear, in patient with prodrome → respiratory failure + rodent/cruise exposure.

Phases of HPS

Prodrome (3–6d, flu-like) → cardiopulmonary (hours, lethal) → diuretic (1–2d, recovery) → convalescent.

Imaging Clues

CXR bilateral interstitial → alveolar infiltrates with perihilar predominance. Echo: preserved EF (distinguishes from cardiogenic shock).

Treatment

Supportive ICU. ARDSnet ventilation. Restrict fluids, capillary leak. Norepinephrine + vasopressin. Early VA-ECMO (50–65% survival vs 35% without). Ribavirin: HFRS only, NOT HPS.

Isolation

Andes virus or undifferentiated: airborne + droplet + contact precautions. Sin Nombre and other US strains: standard precautions sufficient (no P2P).

Reportable

All US states. Notify state public health on suspicion. International outbreak (Andes virus): WHO + CDC notification.

📄 One Pager

Hantavirus One-Pager

2026 alert: Andes virus outbreak on M/V Hondius cruise (Ushuaia, Argentina → Canary Islands). Person-to-person transmission documented. Suspect in any returned passenger or close contact with prodrome → respiratory failure.

Diagnose clinically + confirm with serology/PCR:

Exposure: rodents (US, Four Corners) OR South America / cruise / close contact with Andes case
Prodrome 3–6 days: fever, severe thigh/back myalgia, GI symptoms
Cardiopulmonary phase: rapid hypoxia, bilateral infiltrates, refractory shock
Triad: thrombocytopenia + hemoconcentration + immunoblasts on smear
Echo: preserved EF (rules out cardiogenic shock)
Confirm: hantavirus IgM/IgG, RT-PCR (state lab + CDC)

Treatment package:

Early ICU + airborne/droplet precautions (until species ID'd)
ARDSnet ventilation (6 mL/kg IBW), prone if P/F < 150
Restrict fluids (capillary leak, more fluid worsens edema)
Norepinephrine + vasopressin first; epinephrine or milrinone for myocardial component
Refer for VA-ECMO early if refractory shock, P/F < 80, EF < 40%, lactate rising
Empiric doxycycline (lepto) + broad-spectrum antibiotics until cultures back
Ribavirin for HFRS only within 7 days of onset; NOT for HPS
Notify public health (reportable)
Andes virus: contact tracing of close contacts × 6 weeks

Avoid: liberal crystalloid resuscitation (worsens pulmonary edema), corticosteroids routinely (no benefit), ribavirin for HPS (ineffective), waiting for crash before ECMO referral.

Sources for 2026 outbreak data: WHO Disease Outbreak News (DON599, May 2026); CDC Newsroom; CIDRAP. Clinical content per CDC HPS clinical guidance, IDSA emerging infections updates, and published case series on VA-ECMO outcomes.