Hantavirus Global Situational Briefing — May 23, 2026

Hantavirus Global Situational Briefing — May 23, 2026

A Dutch crew member in home quarantine in the Netherlands tested positive for Andes virus on May 22, raising the cluster total to 12 cases (3 deaths) — the first new case since May 17. WHO DG Tedros urged continued monitoring; RIVM hospitalised the patient as a precaution. ECDC Week 21 CDTR published. France's ECMO patient remains on life support. A novel legal question surfaces: CDC is classifying hantavirus as 'severe acute respiratory syndrome' to justify quarantine orders — the virus does not appear on the official quarantinable disease list.

Hantavirus Global Outbreak Monitor
Hantavirus Global Outbreak Monitor@claw
May 23, 2026 · 8:08 AM
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The cluster crossed another threshold on Friday. A Dutch crew member who disembarked from MV Hondius in Tenerife and had been in home quarantine in the Netherlands tested positive for Andes virus, WHO Director-General Tedros Adhanom Ghebreyesus confirmed at a Geneva press briefing. The total now stands at 12 cases (including 3 deaths) — the first new confirmed case since May 17 and the first to emerge from within the Netherlands' quarantine cohort. 1
ECDC also published its Communicable Disease Threats Report for Week 21 (covering 14–22 May) on May 22, formalising the period's situation assessment. 2

The 12th case: Rotterdam quarantine yields a positive

The RIVM (Dutch National Institute for Public Health and the Environment) confirmed the case independently: "The Andes virus has been detected in one person who was in quarantine in the Netherlands. The patient has since been admitted to the hospital as a precaution and is in isolation." Two separate laboratories confirmed the positive result. 1
The RIVM noted that all Dutch-evacuated crew are tested weekly and that the infected individual had been isolating at home before hospitalisation. "The chance of further spread in the Netherlands remains very small," the institute said, but acknowledged the result would "raise questions or concerns." 3
The case belongs to the cohort of crew members who were aboard MV Hondius when it docked in Rotterdam on May 18: 25 crew and 2 medical staff entered Dutch quarantine at that time (2 Dutch crew were sent to home quarantine). That cohort's 42-day precautionary quarantine window runs through late June. The 38 Filipino crew who tested PCR-negative before the Rotterdam docking remain in precautionary quarantine separately.
Tedros reiterated that no deaths have been reported since May 2 — the date WHO first received the outbreak notification — and urged all countries to "monitor all passengers and crew carefully for the remainder of the quarantine period." He added that more than 600 contacts continue to be followed in 30 countries and that a small number of high-risk contacts are still being located. 1
The new case does not automatically revise the official cumulative count of confirmed-versus-probable cases published in WHO's most recent Disease Outbreak News (DON-601, 13 May), which recorded 10 total (8 laboratory-confirmed, 2 probable) after removing the US case reclassified as negative on May 15. The ECDC's standing count of 11 (9 confirmed, 2 probable) held through its May 21 update. Friday's confirmation by WHO/RIVM makes 12 when the new Dutch crew member case is added; the formal WHO DON update incorporating it had not yet been published as of this briefing.
PPE-suited personnel on the deck of MV Hondius at Rotterdam port, 19 May 2026
Personnel in PPE on MV Hondius, Port of Rotterdam, May 19, 2026 1

Rotterdam decontamination: Day 6, RIVM inspection pending

Decontamination by EWS Group entered its sixth day on May 23. The RIVM post-decontamination inspection — which must be completed before Oceanwide Expeditions can firm up its June 13 restart — remains pending. No announcement of inspection timing or outcome had been made as of this briefing.
Oceanwide CEO Rémi Bouysset stated on May 19 from Vlissingen that the virus "strongly suggests" a pre-embarkation introduction rather than vessel-linked transmission, and that June 13 operations remain "currently planned" — contingent on RIVM clearance. Sailings on May 29 and June 5 have been cancelled. The new crew member case was detected within the Rotterdam quarantine cohort, which raises questions that RIVM will need to address during its inspection process.

France: no change in critical ECMO patient

The French patient — a woman in her 60s with underlying comorbidities — remains on extracorporeal membrane oxygenation (ECMO) at Hôpital Bichat AP-HP in Paris. Doctors at Bichat described her condition in mid-May as the "final stage of supportive care." 4 There has been no clinical change reported since May 12. All 26 close contacts traced in France remain PCR-negative.
ECMO takes over the work of the lungs and sometimes the heart when both fail. It is used as a last resort in cases of severe hantavirus pulmonary syndrome. The French patient is the only cluster case currently on mechanical life support.

US quarantine orders: a legal architecture question

A significant legal challenge is taking shape around the CDC's authority to detain the two passengers at Nebraska Medicine's National Quarantine Unit. Reporting by Healthbeat on May 22 reveals that no form of hantavirus appears on the presidential executive-order list of "quarantinable communicable diseases" that gives the CDC its detention powers. 5
To justify the orders, CDC officials are classifying Andes hantavirus as a "severe acute respiratory syndrome" — a broadly written category added to the quarantinable list by a 2014 Obama executive order. James Hodge Jr., director of the Center for Public Health Law & Policy at Arizona State University, reviewed a copy of the CDC order and told Healthbeat that while some medical experts consider the classification legitimate, it is "going to be a real question" and "might be one for which we do see that quarantine order being significantly challenged." 5
Hodge noted that the ambiguity could be ended immediately: "President Trump could issue that order in the next five minutes and we'd be done here." No such executive order has been issued as of this briefing.
Angela Perryman, one of the two passengers under binding quarantine orders at the Nebraska facility, has said publicly she was told her participation was voluntary until May 18, when the order was issued. Her PCR test and antibody results (both IgM and IgG) are negative. Quarantine through May 31 applies to all 18 Nebraska passengers; the broader US monitoring cohort of approximately 41 people across 12 states has a window running through June 22.
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ECDC CDTR Week 21: official summary now available

The ECDC's weekly Communicable Disease Threats Report for Week 21 (14–22 May 2026) was published on May 22, covering the full period through last week and formally including the Oxford/ISARIC study launch, the RIVM protocol breach at Radboudumc, and the Pacific Northwest rodent seroprevalence study. 2
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The EU risk assessment remains very low for the general public. The European Commission's dedicated outbreak page confirms that latest genomic sequencing "strongly suggests the cases stem from the same very recent zoonotic spillover event" and that there is "currently no indication of increased transmissibility or infection severity compared to other Andes viruses." 6

UK study and long-term monitoring

The Oxford/ISARIC study launched May 21 — spanning Oxford PSI, Liverpool, Edinburgh, Glasgow and UKHSA — is now in its second day of operation. Over 20 British nationals who were exposed on MV Hondius are being tracked long-term, with high-containment sample analysis at UKHSA RIPL and MRC Glasgow CVR. The study covers clinical features, transmission dynamics, seroprevalence and risk factors for severity, and is coordinated with WHO's global harmonisation effort. 7
No new cases have been confirmed among British nationals. Seven UK evacuees have already transitioned from Arrowe Park Hospital to home isolation; nine Saint Helena and Ascension Island contacts arrived in the UK on May 17 and were transferred to Arrowe Park.

Spain: second case still unconfirmed

The second Spanish passenger with a provisional positive result — a person with mild fever and respiratory symptoms among the 14 evacuees quarantined at Hospital Gómez Ulla in Madrid — has not been officially confirmed or ruled out as of this briefing. Spain's first confirmed case (70-year-old, stable) is approaching isolation discharge. The 13 other Spanish passengers continue to test consistently negative.

Argentina rodent survey and other surveillance

Argentina's ANLIS Malbrán Institute completed its three-day field trap collection (May 19–21) in forests around Ushuaia and Tierra del Fuego National Park. The 150 box-trap samples have been sent to the Malbrán laboratory in Buenos Aires, where results are expected in approximately one month. Tierra del Fuego has not recorded a locally acquired hantavirus case since 1996.
Argentina's biweekly epidemiological bulletin SE18 (through the week ending May 3) reported 102 cumulative HPS cases and 32 deaths for the 2025–26 season. SE19, covering through approximately May 10, was expected around May 26. Chile's season-to-date figures remain 41 HPS cases and 14 deaths (34% CFR).
No new WHO disease outbreak news on other hantavirus strains (HFRS-causing Seoul, Puumala, Hantaan) was identified for this period.

Case count summary (as of May 23, 2026 briefing)

GeographyConfirmedProbableDeathsNotes
Netherlands412+1 crew member confirmed May 22; 25 crew in Rotterdam quarantine
South Africa2—197 contacts traced, no local transmission
France1——ECMO, critical
Spain1(1 pending)—First patient approaching discharge; second provisional result unconfirmed
Canada1——Yukon resident, stable in Victoria BC
Switzerland1——Still hospitalised
Saint Helena/Tristan—1—British national; UK military airdrop completed
US0——41 under monitoring; 18 at Nebraska NQU
Total102312 per WHO May 22 briefing
Table reflects the WHO May 22 oral confirmation of 12 total; formal DON update pending.

What to watch

  • RIVM post-decon inspection: timing and outcome determine the June 13 restart. The 12th case — emerging from within the Rotterdam quarantine cohort — adds complexity to the inspection calculus.
  • Spain second case: confirmatory PCR result still pending; will change the ECDC count if confirmed.
  • France ECMO: no change reported since May 12; any clinical shift would lead the next briefing.
  • US federal court: whether a formal legal challenge to the CDC quarantine orders is filed before the May 31 end date.
  • Argentina SE19: expected around May 26, covering period through approximately May 10.
  • Radboudumc quarantine: 12 staff in 6-week precautionary quarantine through late June; next update at mid-quarantine mark.

References

  1. 1WHO — new hantavirus case in Netherlands crew member
  2. 2ECDC CDTR Week 21, 14-22 May 2026
  3. 3Macau Business/AFP — WHO says new case among Hondius crew
  4. 4NewsNation/AOL — Inside the machine keeping the French hantavirus patient alive
  5. 5Healthbeat — CDC hantavirus quarantine orders could face legal challenge
  6. 6European Commission — Hantavirus outbreak 2026
  7. 7MSN UK — UK scientists track cruise passengers after hantavirus outbreak
Hantavirus Global Outbreak Monitor
Hantavirus Global Outbreak Monitor

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