Methodology: How We Classify Cases, Contacts, and Claims

About this tracker

Andes Virus Map is an independent public-source intelligence project tracking the MV Hondius Andes hantavirus cluster. It is not affiliated with any official public health authority. It does not constitute medical advice. It is compiled using official public health agency reports, reputable journalism, and a documented source-classification methodology. For health guidance, consult WHO at who.int or your national health authority.

Every record on this tracker has been checked against at least one Tier 1, Tier 2, or Tier 3 source before classification. Social media claims are used only as leads — they cannot confirm a case, a death, or a country's involvement. Contact monitoring is never counted as confirmed infection.

Source hierarchy

Every record is graded by the quality of its primary source. The hierarchy runs from Tier 1 (most authoritative) to Tier 5 (weakest signal).

Tier 5 sources can generate investigative leads. They cannot confirm a case, a death, a country's involvement, or a transmission event. Any claim originating from Tier 5 sources is classified as Unverified until corroborated by a Tier 1–3 source.

Classification system

Every location on the map is assigned exactly one classification. Classifications are updated when official sources provide new information.

• Confirmed Case

  A human Andes hantavirus case confirmed by PCR laboratory testing, cited by WHO, a national health ministry, or a hospital statement citing lab results.
• Probable Case

  A case described by an official source as probable or clinically compatible, with credible epidemiological linkage to the cluster, awaiting final lab confirmation.
• Suspected Case

  A person reported as symptomatic or hospitalized for possible Andes hantavirus, without lab confirmation. Requires a named hospital, public health agency, or Tier 3 source.
• Death Under Investigation

  A death linked to the cluster where the cause of death has not been officially confirmed as Andes hantavirus by PCR. Includes deaths where samples were not taken.
• Contact Monitoring Only

  People or jurisdictions monitoring exposed individuals after potential contact with a confirmed case. No symptoms, no confirmed infection. Being monitored does not indicate infection.
• Exposure Site

  A location where exposure to Andes virus is believed to have occurred, based on official or credible investigative reporting.
• Travel-Linked Location

  A port, airport, flight route, or transit point involved in the movement of exposed or infected individuals. Not a case location.
• Unverified Claim

  A claim circulating in Tier 4–5 sources without Tier 1–3 corroboration. Excluded from the public map. Visible in analyst layer only.
• Debunked / Not Supported

  A claim contradicted by official sources or lacking support after checking authoritative sources.

Confidence scoring

Every record carries a confidence score from 0 to 100. The score reflects source tier strength, number of corroborating sources, and how recently the record was verified.

• 76–100 (green): Strong support from Tier 1–3 sources. Multiple corroborating channels. Safe to treat as verified.
• 50–75 (amber): Tier 3–4 or single-source reporting. Treat as provisional until additional corroboration is available.
• 0–49 (red): Tier 5 only or single unverified report. Lead value only. Do not treat as confirmed fact.

Confidence scores are reviewed at each 12-hour update cycle and revised when source quality changes.

What we never count as confirmed

The following are explicitly excluded from confirmed case counts on this tracker:

• Contact monitoring
  A person being monitored after exposure is not a case. Georgia, Virginia, Singapore, and other monitoring locations have no confirmed Andes virus infections as of May 7, 2026.
• Social media reports
  Screenshots, viral posts, aggregator accounts, and prediction markets cannot confirm a case regardless of how widely circulated they are.
• Deaths without PCR confirmation
  Three deaths have been reported in the MV Hondius cluster. Only one — a Dutch woman who died in Johannesburg on April 26 — has been PCR-confirmed as caused by Andes hantavirus. The other two deaths remain under investigation.
• Countries with only travel links
  A country whose nationals were aboard the ship but who have not tested positive, and where no health agency has confirmed a case, is not counted as a confirmed case country.

Correction policy

When a record changes — because new evidence emerges, an official source corrects prior reporting, or a claim is debunked — the record is updated immediately and the change is logged in the update log with the reason and new source. We do not silently revise numbers. Every change is visible at andesvirusmap.com/updates.

If you identify an error, a missing source, or a classification you believe is incorrect, the tracker can be reached at contact@andesvirusmap.com.

Update cadence

This tracker is reviewed approximately every 12 hours. Each review checks WHO Disease Outbreak News, CDC Health Alert Network, national health ministry updates, and Tier 3 news sources. Changes are logged with timestamps. The sitemap lastmod date and the update log entry reflect the most recent review.

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