HantaTrackerNet

Mirrored from METHODOLOGY.md

Methodology

This document describes how HantaTracker decides what to publish, how to label confidence, and how to issue corrections. It is the source of truth: the published methodology page mirrors this file byte-for-byte.

Scope — current Andes-virus risk events only

HantaTracker tracks active Andes-virus (Orthohantavirus andesense) risk events. Andes virus is the only hantavirus species with documented person-to-person transmission, and is therefore the only orthohantavirus that carries cluster / multi-country outbreak risk distinct from rodent-spillover incidence. Other hantaviruses — Sin Nombre virus (North America), Choclo virus (Panama), Puumala / Dobrava-Belgrade (Europe), Seoul virus (global), Laguna Negra (Bolivia/Paraguay literature) and others — cause significant human disease but are rodent-borne only and do not propagate between people. They are out of scope for this site.

Displayed totals (cases_global.json, kpis.json) cover only the currently-active Andes-virus event — at present, the 2026 cruise-ship cluster reported in WHO DON 600 (multi-country, Andes virus, H2H transmission documented aboard the vessel, onset 6–28 April 2026). Pre-cluster Andes-virus surveillance (e.g. PAHO's 2025 Americas alert reporting 66 confirmed in Argentina and 35 in Chile through EW 47) is preserved as historical context in the news feed (feed.json) but is no longer included in the displayed counts. Country rows (cases_by_country.json) are currently empty: the WHO DON does not attribute cluster cases to specific destination countries, so per-country rows would have to be inferred. Per-country rows will appear when a Tier-1 source publishes a country-attributed Andes-virus figure.

This scope was adopted on 2026-05-10. The first reduction (drop non-Andes country rows) and the second (drop pre-cluster Andes counts) are both logged in CORRECTIONS.md.

Source prioritization

HantaTracker only publishes figures that can be linked to a Tier-1 official source. Tier-1 always overrides Tier-2.

Tier 1 (required):

  • World Health Organization (WHO) — Disease Outbreak News, Hantavirus Fact Sheet
  • U.S. Centers for Disease Control and Prevention (CDC) — Hantavirus surveillance, NNDSS, WONDER
  • European Centre for Disease Prevention and Control (ECDC) — Hantavirus surveillance, Atlas
  • Pan American Health Organization (PAHO) — Epidemiological alerts and updates

Tier 2 (reference and cross-check):

  • National health ministries (Argentina, Brazil, Chile, Panama, Paraguay, Uruguay, Canada; Belgium, Finland, France, Germany, Hungary, Norway, Russia, Slovenia, Sweden and other European MOHs; China NHC, Japan NIID, Hong Kong CHP, South Korea KDCA, Taiwan CDC; Africa CDC, South Africa NICD)
  • China CDC Weekly
  • CDC Open Data Catalog and APIs (CDC WONDER, CDC Stacks)

SOURCES.md is the canonical user-facing list of every Tier-1 and Tier-2 source. Per-source fetch and update mechanics — URL patterns, query templates, cadence, parser notes — live in the internal INGESTION.md playbook.

When two Tier-1 sources disagree, we publish the most recent and link both. When a newer Tier-1 source revises an earlier Tier-1 figure (for example, the WHO 7 May 2026 news item that revised the cruise-ship cluster from "2 confirmed, 5 suspected" to "5 confirmed, 3 suspected"), we update the value, change the source citation, and log the revision in CHANGELOG.md and DATASOURCES.md. A Tier-2 figure may be quoted only after it can be cross-checked against a Tier-1 figure covering the same reporting period. We never publish a figure derived from an unofficial source, social media, or our own modelling.

Confirmed vs suspected cases

We follow the case definitions used by the publishing authority, taken verbatim where possible. Confirmed and suspected cases are stored in distinct fields in our data files and are never summed in any visualisation. Confirmed cases drive the choropleth fill on the world map; suspected cases appear only in the country detail panel.

Country-row reporting period

A row in cases_by_country.json must carry a Tier-1 figure whose reporting period extends into Q3 2025 (calendar week 27, ≥ 1 July 2025) or later. Older Tier-1 figures (e.g. the Canadian NDSS 2023 count) remain in DATASOURCES.md as historical context but do not appear as country rows.

This rule keeps the country choropleth aligned with what is currently being reported by Tier-1 surveillance, rather than blending fresh outbreaks with multi-year-old aggregates.

Confidence labels

Every country entry carries one of three labels:

  • High — figures published by WHO, CDC, ECDC, or PAHO within the last 14 days.
  • Medium — figures published by a national health ministry within the last 30 days.
  • Low — figures older than 30 days, or from a single source.

The label refers to the freshness and provenance of the figure, not to the trustworthiness of the underlying authority. Most country rows currently carry the Low label because the most recent Tier-1 regional alert (PAHO, 19 December 2025) is more than 30 days old.

R₀ and other modelled values

We do not publish modelled values such as R₀ unless they are quoted from a Tier-1 source. The KPI card displays "Not established" when no source is available. We do not infer.

Update cadence

We aim to:

  • Review Tier-1 sources every 24 hours.
  • Publish updates within 48 hours of source publication.

Failing a stated cadence is worse than not stating one. If we cannot meet this cadence, we will revise this document rather than quietly drift.

Correction policy

If a published figure is later found to be incorrect, we:

  1. Update the figure in the relevant data/*.json file.
  2. Add an entry to CORRECTIONS.md describing what changed, when, and why.
  3. Add a feed item with the tag Correction linking to the corrected source.

Historical snapshots in /snapshots/YYYY-MM-DD/ are never edited after the day they are written. They preserve the record of what was published at the time.

Editorial workflow

Two-person review is required before publishing any of:

  • The first case in a new country.
  • Any death.
  • Any claim of human-to-human transmission.
  • Any R₀ figure.
  • Any vaccine or treatment claim.
  • Any WHO risk-level change.
  • Any correction affecting historical figures.

Single-person review is sufficient for routine case-count updates from existing Tier-1 sources, and for adding a feed item that quotes a Tier-1 source verbatim. Each published change is logged in CHANGELOG.md.

Medical disclaimer

HantaTracker is not medical advice and not a surveillance system. The site is a faithful aggregator of publicly available reports. For clinical guidance, contact your local public-health authority.