Hantavirusseuranta 2026 — MV Hondiuksen tapauslaskuri reaaliajassa | HantaCount

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Glossary

Hantavirus glossary — A to Z

Plain-language definitions of every term you will see in a WHO, ECDC or CDC hantavirus document. 81 entries, cross-linked to our explainers, designed for journalists, clinicians-in-training and curious readers.

A

ACE2: Angiotensin-converting enzyme 2. The cell-surface receptor SARS-CoV-2 uses to enter cells. Hantaviruses use a different receptor (β-integrin); ACE2 is mentioned here only because the question comes up in COVID comparisons.
Active case-finding: Public-health field activity where investigators proactively look for cases (door-to-door, reviewing hospital records, contacting clinicians) rather than waiting for clinicians to report. Used heavily in MV Hondius response.
Aerosol transmission: Spread of an infectious agent via tiny respiratory particles that remain airborne for minutes to hours. Hantaviruses spread by inhaled aerosolised rodent excreta; person-to-person aerosol spread of Andes virus has not been demonstrated.
ANDV (Andes virus): The hantavirus species behind the 2026 MV Hondius outbreak. Carried in nature by Oligoryzomys longicaudatus. The only hantavirus with documented person-to-person transmission. Andes virus profile.
Anti-ANDV antibodies: IgM and IgG antibodies the body produces against Andes virus. IgM appears within days of symptom onset and indicates recent infection; IgG persists for years and indicates past exposure.
Anti-RNP / immunology: Antibodies against ribonucleoprotein. Not directly relevant to hantavirus diagnosis but appears in differential lab work; mentioned here only because the question comes up.
ARDS: Acute Respiratory Distress Syndrome. Severe lung inflammation causing fluid in the alveoli, low oxygen and stiff lungs. Common end-state of severe hantavirus pulmonary syndrome.
Asymptomatic case: An infection without clinical symptoms. Detected through screening. Their existence lowers the true infection-fatality ratio compared with the case-fatality ratio.

B

Biosafety Level 3 (BSL-3): Laboratory containment tier for pathogens that cause serious disease via inhalation. Hantaviruses are handled at BSL-3 in research settings.

C

Cardiopulmonary phase: The dangerous middle phase of HPS, usually beginning 4–10 days after symptom onset. Marked by sudden shortness of breath, low blood pressure and lung fluid. ICU admission within hours improves survival.
Case definition: Standardised criteria used by health authorities to classify a patient as confirmed, probable or suspected. WHO and ECDC publish hantavirus case definitions; rules differ slightly.
Case-fatality ratio (CFR): Deaths divided by clinically apparent cases. For Andes virus historically 30–40%. Different from infection-fatality ratio (IFR), which includes asymptomatic infections in the denominator.
CDC: US Centers for Disease Control and Prevention. Issues hantavirus surveillance bulletins, vessel sanitation guidance, and traveller advisories.
Cohort (exposed cohort): A defined group of people identified by a shared exposure who are then followed forward in time. The 240-passenger MV Hondius roster is the index cohort of the 2026 outbreak.
Contact tracing: Identification and follow-up of people who had close contact with a confirmed case. For Andes virus the close-contact window is roughly the 14 days before symptom onset and through the first week of symptoms.
Convalescent phase: The recovery period after acute illness. For HPS this typically lasts weeks to months and may include reduced exercise tolerance.

D

Deer mouse: Peromyscus maniculatus. The primary North American reservoir for Sin Nombre virus. Native to the western United States and parts of Canada and Mexico.
Differential diagnosis (DDx): The list of conditions a clinician considers when symptoms could fit several diseases. For HPS, the DDx includes severe influenza, CAP, ARDS from sepsis, leptospirosis and Q fever — early HPS looks like all of them.
Disease Outbreak News (DON): WHO's official outbreak notification series. The MV Hondius cluster is documented in DON-599.
Doubling time: Time for case counts to double during an outbreak. Hantavirus is too rare for meaningful doubling-time calculations; the metric is more useful for COVID, measles, or other high-R0 diseases.

E

ECDC: European Centre for Disease Prevention and Control. Issues technical risk assessments and rapid risk assessments for European member states.
ECMO: Extracorporeal Membrane Oxygenation. A heart-lung bypass machine considered for severe HPS when standard ventilation cannot maintain oxygenation. Available only in specialist centres.
ECMO: Extracorporeal Membrane Oxygenation. A heart-lung bypass machine that oxygenates blood outside the body when the patient's lungs cannot. The single most life-saving intervention in severe HPS — survival is meaningfully higher in centres with ECMO capability.
Endemic: An infection routinely present in a defined area at a stable rate. Andes virus is endemic to parts of Argentina and Chile; the MV Hondius cluster is an exported outbreak, not an endemic case.
Endemic region: An area where a disease consistently occurs at baseline rates without external introduction. Andes virus is endemic in Argentine and Chilean Patagonia; Sin Nombre virus is endemic in the US Four Corners region.
Exposure window: The interval during which a person could have been infected. For MV Hondius passengers this is typically the cruise period plus a brief pre-cruise window in Patagonia.

F

Fomite: A non-living object that can carry infectious agents — bedding, door handles, clothing. Hantavirus survives short periods on fomites; this matters for cabin and ship cleaning protocols.

G

GeneXpert (Cepheid): A portable PCR instrument used for rapid molecular diagnosis. The Andes virus Cepheid assay returns results in under 90 minutes from sample — used in the Tristan da Cunha airdrop deployment.

H

Haematocrit: Percentage of blood volume occupied by red cells. A rising haematocrit alongside falling platelets is a characteristic early HPS lab finding caused by capillary leak.
Handavirus (misspelling): Common misspelling of hantavirus (confusing 't' with 'd'). The correct spelling is hantavirus.
Hantivirus (misspelling): Common misspelling of hantavirus. The correct spelling is hantavirus.
Hantovirus (misspelling): Common misspelling of hantavirus. The correct spelling is hantavirus.
Hentavirus (misspelling): Common misspelling of hantavirus (swapping 'a' for 'e'). There is no virus named hentavirus; the correct spelling is hantavirus.
HFRS: Haemorrhagic Fever with Renal Syndrome. The Old World hantavirus disease pattern, caused by Hantaan, Seoul, Puumala and Dobrava viruses. Different clinical course from HPS.
HFRS (Haemorrhagic Fever with Renal Syndrome): The kidney-focused form of hantavirus disease, dominant in Eurasia. Caused by Hantaan, Seoul, Puumala and Dobrava viruses. Case fatality typically 0.5–15% depending on strain. HPS vs HFRS comparison.
Host range: The set of species a virus can infect and replicate in. Hantaviruses have very narrow host ranges with a single primary rodent reservoir per virus species.
HPS: Hantavirus Pulmonary Syndrome (also called Hantavirus Cardiopulmonary Syndrome). The New World hantavirus disease pattern, caused by Sin Nombre, Andes and related viruses. Lung-dominant, high mortality. Symptoms guide.
HPS (Hantavirus Pulmonary Syndrome): The lung-focused severe form of hantavirus disease, dominant in the Americas. Caused by Sin Nombre virus, Andes virus and related strains. Case fatality 30–40%. HPS vs HFRS comparison.
Huntavirus (misspelling): Common misspelling of hantavirus. No such virus exists; the correct term is hantavirus.

I

ICD-10 B33.4: International Classification of Diseases code for Hantavirus Cardiopulmonary Syndrome. Used in clinical records and death-certificate coding.
IHR / International Health Regulations: WHO 2005 framework requiring countries to report defined public-health events within 24 hours. The MV Hondius cluster was reported under IHR by the Netherlands on 2 May 2026.
Incubation period: The interval between exposure and symptom onset. For Andes virus typically 14–28 days, occasionally up to 6 weeks. Longer than most respiratory viruses.
Index case: The first identified case in an outbreak. Not always the original infection — that's the primary case. The index case for MV Hondius is the first symptomatic passenger documented on April 28, 2026.
Infection-fatality ratio (IFR): Deaths divided by total infections (symptomatic plus asymptomatic). Lower than CFR. For Andes virus the IFR is unknown because we don't sample asymptomatic exposures systematically.
IQR / Interquartile range: Statistical spread metric used in case-series reporting. WHO reports incubation as 'median 14 days, IQR 10–21' to convey both the typical and the realistic range.
Isolation (medical): Separation of an infected person from healthy people. For Andes virus, droplet/contact isolation is recommended even though risk is low — analogous to TB isolation.

M

Mortality rate: Deaths per population per unit time, distinct from case-fatality ratio (which is deaths per case). Hantavirus mortality rate in the general population is essentially zero outside endemic regions.
Multi-country event: WHO designation for an outbreak with cases identified in more than one country. The MV Hondius cluster is officially a multi-country event under the International Health Regulations.

N

N95 respirator: A particulate respirator that filters at least 95% of airborne particles. Recommended for healthcare workers caring for confirmed or suspected hantavirus cases.
N95 respirator: Filtering facepiece that removes 95% of airborne particles 0.3 microns or larger. Required PPE for cleaning rodent-contaminated spaces — surgical masks are insufficient.
Narrative review: A non-systematic literature summary, used here when describing the broader hantavirus evidence base. Distinct from a Cochrane systematic review.

O

Outbreak: Cases of disease above the expected baseline in a defined population, place and time. Two confirmed cases of Andes virus in Europe is an outbreak; one is an alert.
Outbreak investigation: The structured public-health response to a cluster — case-finding, line-listing, hypothesis generation, source identification, and intervention. The MV Hondius outbreak follows the standard CDC/WHO outbreak investigation playbook.

P

Patient zero / index case: The first identified case in an outbreak. The MV Hondius index case is one of two passengers who died on board on 2 May 2026; the original infection source remains under investigation.
PCR: Polymerase Chain Reaction. The lab method that detects viral RNA. The diagnostic gold standard for hantavirus, alongside serology.
PPE: Personal Protective Equipment. For hantavirus contact the recommended set includes N95 respirator, eye protection, gown and gloves.
PPE / Personal Protective Equipment: Gloves, mask, eye protection and gowns used to prevent occupational exposure. Hantavirus PPE for cleaning means N95 + nitrile gloves at minimum.
Primary case: An infection acquired from the original source (in hantavirus, usually the rodent reservoir or, exceptionally for Andes, an earlier human case).
Prodromal phase: The early flu-like phase of HPS — fever, body aches, headache, sometimes nausea. Lasts 3–7 days before the cardiopulmonary phase. The window in which most patients first seek care.
Prodrome / prodromal phase: Early non-specific symptoms (fever, fatigue, muscle aches) that precede the more recognisable phase of illness. The HPS prodrome is 3–7 days and looks like flu — the diagnostic challenge.
Puumala virus: An Old World hantavirus carried by the bank vole. Causes a milder HFRS variant called nephropathia epidemica. Endemic across northern Europe and parts of Russia.

R

R-effective (Rt): The average number of secondary cases produced by one infected person at a given time, accounting for current immunity and behaviour. ANDV Rt is normally well below 1 — outbreaks fizzle out.
R₀ (basic reproduction number): The average number of secondary cases generated by one infected person in a fully susceptible population. For Andes virus: well below 1 in the general population, around 1 in close-contact households. Andes virus R0 deep dive.
Reservoir: The animal species that maintains a virus in nature without major harm to itself. The reservoir for Andes virus is the long-tailed pygmy rice rat.
Ribavirin: An antiviral drug studied for hantaviruses. Used investigationally for HFRS in some Asian protocols; not standard of care for ANDV pulmonary syndrome.

S

Secondary attack rate: The proportion of contacts of a known case who themselves get infected. The 1996 El Bolsón ANDV cluster had a secondary attack rate of roughly 12% among household contacts.
Secondary case: A case acquired from a primary case rather than from the original source. Existence of secondary cases is what defines person-to-person transmission.
Seroconversion: The development of detectable antibodies after infection. For hantaviruses this typically occurs within 1–2 weeks of symptom onset.
Serotype: A subdivision of a viral species based on antigenic profile (which antibodies recognise it). Different hantavirus serotypes correspond roughly to different rodent reservoirs and geographical regions.
Sin Nombre virus: The hantavirus responsible for the 1993 Four Corners outbreak in the US. The most common cause of HPS in North America. Reservoir: deer mouse.
Source containment: Measures to prevent further spread from the index source — for hantavirus, controlling rodent reservoirs, decontaminating shared environments, and isolating identified cases.
Spillover event: A pathogen jumping from its animal reservoir to a human. Each new HPS case is technically a spillover — they do not result from human chains except in rare ANDV clusters.
Supportive care: Treatment that addresses symptoms and physiology rather than the underlying infection. Hantavirus has no specific antiviral; supportive care (oxygen, fluids, ECMO if needed) is the entire treatment.

T

Tertiary case: A case acquired from a secondary case (i.e., third generation). The appearance of clearly tertiary cases would mean the chain is self-sustaining; this has not been documented for Andes virus.
Thrombocytopenia: Low platelet count. A near-universal finding in HPS prodrome and a useful triage signal when the clinical picture is otherwise non-specific.

V

Vector-borne (it isn't): Hantaviruses are not vector-borne. They are zoonotic — transmitted directly from rodents — without an arthropod intermediate like a mosquito or tick.
Vessel Sanitation Program: CDC programme that inspects cruise ships for sanitation, including rodent control. Audits are public; MV Hondius records can be queried at the CDC VSP database.
Viral load: The amount of virus in a sample (blood, throat swab, urine). High viral load early in HPS correlates with worse outcomes; serial measurement can guide ICU triage.

W

WHO: World Health Organization. Issues Disease Outbreak News, technical guidance and the International Health Regulations under which multi-country events like MV Hondius are coordinated.

Z

Zoonotic: An infection that naturally jumps from a non-human animal to humans. All hantaviruses are zoonotic; the rodent is the reservoir and humans are accidental hosts.

Β

β3 integrin (ITGB3): The cell-surface receptor pathogenic hantaviruses use to enter human endothelial cells. Polymorphisms in the ITGB3 gene have been investigated as host-genetic risk factors for severe HPS.

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