Introduction
-- WHO advises Member States to implement a risk-based approach to the identification, monitoring, and management of contacts of probable or confirmed Andes virus (ANDV) cases from the MV Hondius cruise ship and related to the event on that cruise ship.
-- ANDV has been associated with limited human-to-human transmission, usually associated with close and prolonged contact.
Operational outbreak definitions
-- Suspected case:
- anyone who shared or visited a conveyance where there has been a confirmed or probable ANDV case
* AND *
- with acute (or history of) symptoms compatible with ADNV infection, including fever (38°C or above), myalgia, chills, acute gastrointestinal (e.g. nausea, vomiting, diarrhoea, abdominal pain) or acute respiratory (e.g. cough, shortness of breath, chest pain, difficulty breathing) symptoms.
-- Probable case:
- a person with signs and symptoms of a suspected case that has been evaluated by a health professional
* AND *
- has a known epidemiological link with a confirmed or probable ANDV case
* AND *
- for which laboratory results are not available.
-- Confirmed case:
- person with laboratory confirmation of ANDV through RT-PCR or serology testing.
-- Non-case*:
- a suspected or probable case who tests negative for ANDV by RT-PCR or serology.
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{*} Non-cases who develop symptoms compatible with the suspected case definition after a negative test and within the maximum incubation period after last exposure to a probable or confirmed case should be retested and reclassified as appropriate.
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-- Contact:
- a person who was exposed to a confirmed or probable case of ANDV while the case was infectious, through interactions consistent with exposure to respiratory secretions, saliva, blood, or other bodily fluids; including
• Direct physical contact, including exposure to saliva or other bodily fluids (e.g. care giving, intimate contact, sharing a bed, etc).
• Close proximity exposure, defined as being within 2 meters for a cumulative period of more than 15 minutes (e.g. face to face interactions, shared meals or other social gatherings)
• Exposure in enclosed or shared spaces (e.g. multiple days on same ship, aircraft/conveyance seating proximity, etc.)
• Unprotected exposure in healthcare settings, particularly during patient care, as well as laboratory exposure.
-- Incubation period (time between infection and symptom onset):
- ranges 1-6 weeks (with longer incubation reported rarely), most commonly reported between two and four weeks (median 18 days).
-- Infectious period:
- from onset of symptoms onset until the recovery or death of the case.(1)
-- Period of highest infectiousness:
- from onset (starting with non-specific febrile presentation) and throughout the prodromal and symptomatic phase (approximately for one week).
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NOTE:
Highest risk of transmission has been reported at the prodromal phase. There are very early non-specific symptoms that might be difficult to recognize. In addition, while pre-symptomatic transmission has not been documented in the past, there has been anecdotal documentation of pre-symptomatic PCR positivity in the blood. As a precautionary measure and out of caution, it is suggested that contacts be identified from two days prior to reported symptom onset of a confirmed or probable case.
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-- Date of last exposure:
- date of last contact with a confirmed or probable case. For MV Hondius passengers and crew members, this is the date of disembarkation.
Identification and classification of contacts
-- Given the limited but documented potential for human-to-human transmission associated with ANDV, a precautionary approach to contact identification, listing, tracing and follow-up is recommended.
-- During epidemiological case investigations, Member States should identify contacts of ANDV cases, and based on the exposure risk, classify them into high- or low-risk categories according to the intensity and duration of exposure, proximity to the case, type of interaction (e.g., direct contact vs. enclosed or shared spaces) and use of personal protective equipment. The questionnaire in Annex 1can be used to assess the risk of each contact.
Risk-based classification of contacts
-- Based on information available and ongoing epidemiological, clinical and environmental investigations, and applying the precautionary principle, WHO considers all passengers and crew currently on board the MV Hondius to be high-risk contacts.
-- High-risk contacts
- Individuals with one or more of the following exposures with a probable or confirmed ANDV case:
• Persons sharing the same cabin.
• Intimate partners or individuals with direct physical contact.
• Persons sharing a bathroom or sleeping space.
• Persons within approximately 2 meters for prolonged periods (>15 minutes cumulative) indoor.
• Persons participating in shared meals, prolonged social interactions, or caregiving activities.
• Healthcare workers with unprotected exposure.
• Healthcare workers exposed without appropriate PPE during aerosol-generating medical procedures.
• Aircraft passengers seated in the same row, and within two rows in all directions from the case.
• Cabin crew or transport staff with interaction with the case.
• Persons handling linens, clothing, other personal items of the case, medical waste, or body fluids without appropriate PPE.
-- Low-risk contacts
- Individuals who have attended an event, been in a conveyance with a probable or confirmed ANDV case but have no known direct or prolonged close interaction, with the case including:
• Other passengers or crew without cabin sharing or prolonged close interaction on a ship.
• Aircraft passengers outside the defined seating proximity zone.
• Brief transit or port contacts not meeting the high-risk contact definition.
• Individuals sharing large open-air spaces without prolonged interaction.
• Healthcare providers using appropriate PPE throughout exposure.
-- Management and follow-up of contacts
- High-risk contacts – Active monitoring and in designated facility or home quarantine
• Public health authorities should conduct daily follow-up for 42 days after last known exposure as defined above, during which time the contact should be advised to avoid contact with other persons through remaining in a designated facilities or at home, depending on national guidelines and capacities.
• Follow-up may occur by telephone, messaging, telehealth, or in person.
• High-risk contacts (including healthcare workers) should refrain from returning to work for designated period.
• High-risk contacts should avoid contact with other household members, and where possible and remain in a separate room.
• In case social interactions are unavoidable, high-risk contacts should wear a respirator (e.g.FFP2 or N95 respirator), practice physical distancing, and observe regular hand hygiene.
• All unnessary travel, nationally and internationally, should be discouraged for 42 days.
• Movement of the contact out of the jurisdiction of public health authorities in charge of their follow-up may be allowed for life-threatening or humanitarian reasons, provided that arrangements are made with the public health authorities in the jurisdiction at destination, including internationally through IHR channels.
• During daily follow-up, any symptoms: temperature, fever, fatigue or malaise, muscle ache, headache, gastrointestinal symptoms, respiratory symptoms, should done using a contact follow-up form (see Annex 2) and communicated as promptly as possible to the responsible local, national and international public health authorities.
• Any high-risk contact developing symptoms compatible with hantavirus infection should be promptly isolated, clinically evaluated and tested.
• Contacts should receive:
o Written information on symptoms to look out for.
o Emergency contact numbers.
o Instructions regarding healthcare seeking and testing.
-- Low-risk contacts – Passive self-monitoring
• Self-monitor daily, and for 42 days from last exposure, for fever (using a thermometer, recording daily temperature), malaise, muscle ache, headache, gastrointestinal symptoms, respiratory symptoms, using a contact follow-up form (see Annex 2).
• No restrictions of the contact’s daily occupational or recreational activities are warranted.
• Low-risk healthcare workers should notify occupational health at their respective workplace and follow local policy with respect to return to work.
• Movement of the contact out of the jurisdictions of public health authorities in charge of their follow-up should be allowed, provided that arrangements are made with the public health authorities in the jurisdiction at destination, including internationally.
• Any symptoms: temperature, fever, fatigue or malaise, muscle ache, headache, gastrointestinal symptoms, respiratory symptoms, should be promptly reported to local health authorities.
• Any low-risk contact developing symptoms compatible with hantavirus infection should promptly isolated, clinically evaluated and tested.
• Contacts should receive:
o Written information on symptoms to look out for.
o Emergency contact numbers.
o Instructions regarding healthcare seeking and testing. and healthcare seeking
Plans for updating
“WHO continues to monitor the situation closely for any changes that may affect this interim guidance. Should any factors change, WHO will issue a further update. Otherwise, this interim guidance will expire one year after the date of publication.”
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© World Health Organization 2026. Some rights reserved. This work is available under the CC BY-NC-SA 3.0 IGO license.
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1 This may be updated as more evidence becomes available.
Source:
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