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.

RoundsRx

Dashboard

Overview

Recent

Rotations

Quick Reference

Antibiotic Guide Analgesia Guide Sedation Guide Bowel Regimen Electrolyte Replacement Pain Management & Conversions Drug Interactions Anticoag Reversal IV Fluid Guide Inotropes Guide Vasopressors Insulin Guide Code Blue & Rapid Response Procedures Guide ECG Interpretation Lab Interpretation Radiology Quick Ref GCS Pocket Card Admission Orders & I-PASS Landmark Trials

Tools

💎 Clinical Pearls 🧠 Pimp Me Quiz 🧮 Clinical Calculators 📰 What's New 🎓 Intern Survival Guide ✅ Rounding Checklists 🩺 Procedure Guides ⚡ Electrolyte Replacement 💧 IV Fluids Guide 🩸 Transfusion Guide 💓 ECG Pattern Guide 🧪 Lab Interpretation Guide 📱 QR Poster 🔗 Resources 🎙️ Channels & Podcasts 🎮 Medical Games 🏛️ Famous Cases 🎬 Media Library

ℹ️ About

Available offline

2026 OUTBREAKFoodborneInfectious DiseaseGI / Parasitic

Cyclosporiasis (Cyclospora cayetanensis)

Coccidian parasite spread by fecal-contaminated fresh produce and water. Causes prolonged, relapsing, watery diarrhea with profound fatigue, anorexia, and weight loss. Routine stool ova-and-parasites misses it, so you must specifically request Cyclospora testing. TMP-SMX is the only reliably effective treatment, and there is no good alternative for sulfa-allergic patients.

🔍 Overview

🚨 Active 2026 US Outbreak (as of July 2026): CDC issued a Health Alert Network notice for a surge in domestically acquired cyclosporiasis. Since May 1, 2026, CDC has logged 4,173 laboratory-confirmed domestic cases plus more than 7,400 additional probable cases still under investigation, a case count outpacing the prior season by more than 6-to-1. A linked traceback investigation identified 1,645 confirmed cases across 34 states (age range 2 to 95, median 44, 56% female).

Source and recall: The traceback points to shredded iceberg lettuce (Taylor Farms de Mexico) served at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio, and West Virginia. On July 17, 2026, Taylor Farms de Mexico recalled all iceberg lettuce sourced from central Mexico.

Why this matters clinically: Suspect cyclosporiasis in any patient with prolonged (more than 1 week) or relapsing watery diarrhea, especially with a fresh-produce exposure. Standard stool ova-and-parasites (O&P) does not detect Cyclospora, so the diagnosis is missed unless you order it specifically. Sources: CDC HAN (HAN00531, 2026); CDC Cyclosporiasis Outbreak Investigation (July 2026); Infection Control Today, 2026.

What Is It

Cyclospora cayetanensis is a single-celled coccidian protozoan parasite (same broad family as Cryptosporidium and Cystoisospora). It infects the small-bowel epithelium and causes a prolonged, self-limited but often debilitating diarrheal illness in immunocompetent hosts, and a more severe, protracted illness in the immunocompromised.

Transmission & Why Outbreaks Happen

Fecal-oral, via contaminated food or water, not directly person-to-person. Freshly passed oocysts are not immediately infectious: they need days to weeks in the environment to sporulate (mature). This is why direct person-to-person spread does not occur, and why hospital contact precautions beyond standard hygiene are not required.
Classic vehicles are fresh produce that is eaten raw and can hold onto oocysts: leafy greens (iceberg/romaine lettuce), fresh herbs (cilantro, basil), raspberries, blackberries, snow peas, and mesclun. The 2026 US outbreak is lettuce-linked.
Seasonality: US cases cluster in spring and summer (May through August), which is why an outbreak in July fits the expected pattern.
Washing does not reliably remove it. Oocysts adhere tightly to produce surfaces and are resistant to routine chlorine and sanitizer washes, so ordinary rinsing cannot be relied on to make contaminated produce safe (see Prevention).

Clinical Course (the pattern that gives it away)

Incubation is a median of ~7 days (range roughly 2 to 14 days) after ingestion, longer than most bacterial foodborne illness, so patients often cannot pin it to a single meal.

Watery, non-bloody diarrhea is the hallmark, often frequent and profuse.
Relapsing / remitting course is highly characteristic: patients improve, then relapse. Untreated illness commonly lasts several weeks and can persist a month or more, which is why it is a leading cause of prolonged traveler's and foodborne diarrhea.
Profound anorexia, fatigue, and weight loss are disproportionate to a "simple" gastroenteritis and are a useful clue.
Other features: abdominal cramping, bloating, marked flatulence, nausea, low-grade fever, and myalgias.
Immunocompromised (advanced HIV, transplant): more severe, voluminous, and protracted diarrhea; biliary tract involvement (acalculous cholecystitis) can occur.

🧪 Workup

The single most important teaching point: a routine stool ova-and-parasites (O&P) exam does NOT detect Cyclospora. The lab must be specifically asked to look for it (special stains or a molecular GI panel that includes Cyclospora). If you do not order it by name, a negative "O&P" falsely reassures you and the diagnosis is missed.

When to Suspect

Watery diarrhea lasting more than ~1 week, or a relapsing diarrheal course, in an otherwise immunocompetent patient. Prolonged duration is the key trigger, since most bacterial and viral gastroenteritis resolves in days.
Fresh-produce or contaminated-water exposure, restaurant/outbreak link, or travel to an endemic region (Latin America, South/Southeast Asia).
Diarrhea plus disproportionate fatigue, anorexia, and weight loss.

Diagnostic Tests

Test	What it shows / why it works	Notes
Molecular multiplex GI PCR panel	Most sensitive and fastest. Several FDA-cleared gastrointestinal pathogen panels include Cyclospora cayetanensis. Detects parasite DNA directly.	PREFERRED where available Increasingly the first-line test; does not depend on catching oocysts on a slide.
Modified acid-fast stain (modified Ziehl-Neelsen / Kinyoun)	Oocysts are 8 to 10 μm (about twice the size of Cryptosporidium, ~4 to 6 μm). They are variably acid-fast: in the same field, oocysts range from unstained to light pink to deep red.	Requires the lab to be told to look; not part of a routine O&P.
UV autofluorescence microscopy	Oocysts autofluoresce blue-green under ultraviolet epifluorescence against a dark background. Rapid and sensitive screening method.	Sensitive but not specific; confirm with stain or molecular test.
Stool wet mount / O&P	Standard parasite exam. Insensitive for Cyclospora and easily missed.	DOES NOT rule it out A negative routine O&P does not exclude cyclosporiasis.

Collect More Than One Specimen

Oocysts are shed intermittently and at low levels, even in patients with profuse diarrhea. A single negative stool does not exclude the diagnosis. If clinical suspicion is high and the first specimen is negative, collect at least 2 to 3 stool specimens on different days and process them with a sensitive method (molecular panel or special stains). This is the same reason a single sample under-detects the parasite in outbreak surveillance.

Supporting Labs

CBC: eosinophilia is not typical (unlike many helminths), so a normal eosinophil count does not argue against it.
BMP: assess for dehydration and electrolyte loss from prolonged diarrhea.
Consider co-testing for other stool pathogens; Cyclospora can co-occur with other foodborne organisms in an outbreak setting.

💊 Management

Treatment Approach

Antiparasitic therapy: TMP-SMX (trimethoprim-sulfamethoxazole) is the treatment of choice. It is the only reliably effective agent. Untreated illness is prolonged and relapsing, so treating shortens the course and prevents relapse rather than just easing symptoms.
Rehydration and supportive care: oral rehydration for most; IV fluids if volume-depleted from profuse or prolonged diarrhea. Replace electrolytes as needed.
Immunocompromised patients need more: higher doses, longer duration, and often long-term secondary suppression (see Medications), because relapse is common once therapy stops.
Public health reporting: cyclosporiasis is a nationally notifiable condition. Report confirmed and suspected cases to your state or local health department, especially during the current outbreak, so traceback and recalls can proceed.

Response and follow-up: On TMP-SMX, symptoms typically begin improving within a few days. If diarrhea does not improve after completing therapy, reconsider the diagnosis, check for a co-infection, and consider immunocompromise (which warrants a longer course). Persistent or recurrent symptoms in an immunosuppressed patient are an indication for extended treatment plus suppressive therapy.

What NOT to Do

Do not rely on a routine O&P to exclude it before treating a compatible prolonged/relapsing diarrhea, order the specific test.
Do not expect antibacterial "traveler's diarrhea" regimens to cover it. Azithromycin and standard fluoroquinolone empiric dosing are not reliable Cyclospora therapy; the parasite needs TMP-SMX.
Do not stop antiparasitic therapy early in the immunocompromised, relapse is the rule without an adequate course and suppression.

💉 Medications

Drug Regimens

Agent	Dose & Duration	Role / Why
TMP-SMX (Bactrim/Septra) DS 1ST LINE	1 double-strength tablet (TMP 160 mg / SMX 800 mg) PO twice daily × 7 to 10 days (immunocompetent adults and children over 2 months). Pediatric: TMP 5 mg/kg / SMX 25 mg/kg PO BID.	The only reliably effective agent. 7 to 10 days covers the full course and prevents the characteristic relapse; shorter courses risk recurrence.
TMP-SMX (immunocompromised)	Higher dose / longer course during acute illness, then secondary suppression: 1 DS tablet PO 3 times weekly while immunosuppressed (e.g., advanced HIV until immune reconstitution).	Immunosuppressed patients relapse without prolonged therapy and maintenance suppression, mirroring the approach used for other coccidian parasites in HIV.
Nitazoxanide (Alinia) SULFA ALLERGY	500 mg PO twice daily × 7 days (adult).	Considered for true sulfa allergy, but evidence is limited and efficacy is inconsistent. No alternative matches TMP-SMX.
Ciprofloxacin SULFA ALLERGY	500 mg PO twice daily × 7 days (adult).	Second-line for sulfa-allergic patients. Less effective than TMP-SMX with slower symptom resolution; use when nitazoxanide is unavailable or fails.

Sulfa allergy is the hard problem: CDC states that no highly effective alternative has been identified for patients who cannot take a sulfonamide. Nitazoxanide and ciprofloxacin are the fallback options, both less reliable than TMP-SMX. For a documented, non-severe sulfa reaction, weigh the benefit of the far more effective TMP-SMX against the allergy history, and involve allergy/ID when the illness is severe or prolonged.

🛡️ Prevention

Food & Water Safety

Washing produce reduces but does not eliminate risk. Cyclospora oocysts stick tightly to produce and resist routine chlorine/sanitizer washing, so rinsing cannot be relied on to make contaminated produce safe. During an active outbreak, avoiding the implicated product is the only reliable measure.
During the 2026 outbreak: follow CDC/FDA advisories, avoid recalled iceberg lettuce (Taylor Farms de Mexico, central-Mexico sourced), and heed restaurant-specific warnings.
Cooking kills the parasite; the risk is from raw/fresh produce. When in doubt in a high-risk period, cooked produce is safe.
Travelers to endemic regions should follow safe food and water practices (avoid raw produce and untreated water) during spring/summer months when transmission peaks.

Public Health

Report cases. Cyclosporiasis is nationally notifiable; prompt reporting lets public health link cases, identify the food vehicle, and trigger recalls that stop the outbreak.
No person-to-person precautions beyond standard hygiene are needed in the hospital, because freshly shed oocysts are not infectious until they sporulate in the environment. Standard hand hygiene is sufficient.
No vaccine exists; prevention is entirely food/water safety and outbreak avoidance.

🩺 Rounds

Pimp Questions

A patient has 12 days of watery diarrhea and a negative stool O&P. Why might the O&P be falsely negative, and what do you order?

Routine O&P does not detect Cyclospora, which requires specific testing: a modified acid-fast stain, UV autofluorescence, or a molecular GI PCR panel that includes Cyclospora. Oocysts are also shed intermittently, so collect 2 to 3 specimens on different days. A single negative routine O&P never excludes cyclosporiasis in a compatible prolonged/relapsing diarrhea.

What is the treatment of choice for cyclosporiasis, and the dose?

TMP-SMX (trimethoprim-sulfamethoxazole). Immunocompetent adults: 1 DS tablet (160/800 mg) PO BID × 7 to 10 days. It is the only reliably effective agent. The 7 to 10 day course prevents the classic relapse. Immunocompromised patients need higher/longer dosing plus suppressive therapy (1 DS tablet 3×/week).

Your patient has a true sulfa allergy. What are the options and the caveat?

Nitazoxanide 500 mg PO BID × 7 days or ciprofloxacin 500 mg PO BID × 7 days. The caveat: no highly effective alternative exists, both are less reliable than TMP-SMX (cipro is slower and less effective; nitazoxanide evidence is limited and inconsistent). For a mild sulfa reaction with severe illness, TMP-SMX may still be preferred after weighing risk.

How does Cyclospora spread, and does it require contact isolation in the hospital?

Fecal-oral via contaminated food or water (fresh produce), not person-to-person. Freshly passed oocysts are non-infectious until they sporulate over days to weeks in the environment. So no special contact precautions are needed beyond standard hand hygiene, and household/hospital transmission from a patient does not occur.

How do you distinguish Cyclospora from Cryptosporidium on a modified acid-fast stain?

Size. Cyclospora oocysts are 8 to 10 μm, roughly twice the diameter of Cryptosporidium (~4 to 6 μm). Cyclospora is also variably acid-fast (oocysts stain unevenly from unstained to deep red in the same field) and autofluoresces blue-green under UV. Molecular GI panels distinguish them definitively.

Clinical Examples

📋 Case 1, Outbreak-linked prolonged diarrhea

Patient: 44F, healthy, presents with 10 days of frequent watery, non-bloody diarrhea that briefly improved then relapsed. Marked fatigue, anorexia, and 5-lb weight loss. Ate at a fast-food restaurant with shredded lettuce ~1 week before onset.

Key findings: Afebrile to low-grade fever, mild orthostasis, no eosinophilia. Initial routine stool O&P negative. Local outbreak of cyclosporiasis reported.

Management:

Ordered Cyclospora-specific testing (molecular GI panel) rather than trusting the negative O&P
Molecular panel positive for Cyclospora cayetanensis
TMP-SMX DS 1 tab PO BID × 7 to 10 days + oral rehydration
Reported to the local health department (outbreak traceback)

Teaching point: Prolonged/relapsing watery diarrhea + fresh-produce exposure + negative routine O&P is the classic trap. Order the specific test and treat with TMP-SMX.

📋 Case 2, Sulfa-allergic patient

Patient: 52M with documented sulfonamide allergy (prior urticaria), 2 weeks of relapsing watery diarrhea, weight loss, confirmed Cyclospora on molecular panel.

Management:

Cannot use first-line TMP-SMX given allergy history
Started nitazoxanide 500 mg PO BID × 7 days; counseled that response may be incomplete
Ciprofloxacin 500 mg PO BID × 7 days held as backup if no improvement
Close follow-up arranged given the lack of a highly effective non-sulfa option

Teaching point: There is no equal substitute for TMP-SMX. Nitazoxanide or ciprofloxacin are fallbacks, and the patient needs follow-up because response is less reliable.

📋 Case 3, Immunocompromised host

Patient: 39M with advanced HIV (CD4 40), profuse, voluminous, protracted watery diarrhea for over 3 weeks, dehydration, RUQ discomfort.

Key findings: Cyclospora confirmed; ultrasound suggests acalculous cholecystitis (biliary involvement can occur in advanced immunosuppression).

Management:

Higher-dose, longer-course TMP-SMX for acute illness
Secondary suppression (1 DS tablet PO 3×/week) until immune reconstitution on ART
Aggressive rehydration and electrolyte repletion
Start/optimize antiretroviral therapy, immune recovery is the durable fix

Teaching point: In advanced immunosuppression, cyclosporiasis is severe and relapsing. Treat longer and maintain suppression until CD4 recovers.

🎯 Summary

At a Glance

Organism

Cyclospora cayetanensis, a coccidian protozoan parasite of the small bowel.

2026 Outbreak

US surge, 4,173 confirmed + 7,400 probable since May 1, 2026 (CDC HAN). Traceback: shredded iceberg lettuce (Taylor Farms de Mexico) at Taco Bell in IN, KY, MI, OH, WV. Recall July 17, 2026.

Transmission

Fecal-oral via contaminated fresh produce/water. NOT person-to-person (oocysts must sporulate in the environment first).

Incubation

Median ~7 days (range ~2 to 14), longer than most bacterial foodborne illness.

Hallmark

Prolonged, relapsing watery non-bloody diarrhea with marked fatigue, anorexia, weight loss. Untreated: weeks to a month+.

Diagnosis

Routine O&P MISSES it. Order specific testing: molecular GI panel (preferred), modified acid-fast stain, or UV autofluorescence. Oocysts 8 to 10 μm.

Multiple Specimens

Intermittent shedding, so collect 2 to 3 stools on different days. One negative does not exclude.

Treatment

TMP-SMX DS 1 tab PO BID × 7 to 10 days. Only reliably effective agent. Prevents relapse.

Sulfa Allergy

No highly effective alternative. Nitazoxanide 500 mg BID × 7d or ciprofloxacin 500 mg BID × 7d, both less reliable.

Immunocompromised

Severe/protracted, biliary involvement possible. Higher-dose, longer course + suppressive TMP-SMX 3×/week until immune recovery.

Reportable

Nationally notifiable. Report to public health to enable traceback and recalls.

Prevention

Washing does not fully remove oocysts. Avoid implicated produce during outbreaks. Cooking kills it. No vaccine.

📄 One Pager

Cyclosporiasis One-Pager

2026 alert: US cyclosporiasis surge (CDC HAN). Shredded iceberg lettuce (Taylor Farms de Mexico) served at Taco Bell in IN, KY, MI, OH, WV; central-Mexico iceberg lettuce recalled July 17, 2026. Suspect in any prolonged or relapsing watery diarrhea with a fresh-produce exposure.

Diagnose, do NOT trust a routine O&P:

Watery, non-bloody, prolonged (more than 1 week) or relapsing diarrhea + fatigue, anorexia, weight loss
Incubation median ~7 days; fresh-produce/water or outbreak/travel exposure
Order Cyclospora-specific testing: molecular GI PCR panel (preferred), modified acid-fast stain, or UV autofluorescence
Oocysts 8 to 10 μm, variably acid-fast, autofluoresce blue-green
Intermittent shedding, collect 2 to 3 specimens on different days; one negative does not exclude
Eosinophilia is NOT expected, a normal count does not argue against it

Treatment:

TMP-SMX DS (160/800 mg) 1 tab PO BID × 7 to 10 days, immunocompetent adults/children over 2 months (only reliably effective agent; prevents relapse)
Rehydrate (oral, or IV if volume-depleted); replace electrolytes
Sulfa allergy: nitazoxanide 500 mg BID × 7d OR ciprofloxacin 500 mg BID × 7d, both less reliable, no highly effective substitute
Immunocompromised: higher-dose, longer course + suppression (1 DS tab 3×/week) until immune recovery
Report to public health (nationally notifiable)

Avoid: ruling it out on a negative routine O&P; expecting azithromycin or standard fluoroquinolone empiric therapy to cover it; stopping therapy early in the immunocompromised (relapse); relying on washing to make contaminated produce safe.

Sources: CDC Cyclosporiasis clinical guidance and Health Alert Network notice (HAN00531, 2026); CDC Cyclosporiasis Outbreak Investigation (July 2026); ADA/IDSA-aligned references and Merck Manual Professional for clinical/diagnostic detail.