Why Hantavirus triage is hard and why it matters

Hantaviruses cause two clinically severe zoonotic syndromes. Hantavirus Pulmonary Syndrome (HPS) is reported with case-fatality between 30 and 50 percent in unprepared settings, and Hemorrhagic Fever with Renal Syndrome (HFRS) reaches the tens to hundreds of thousands of cases per year across Eurasia. The hardest moment of clinical care for either syndrome is the earliest one. The prodromal phase looks like influenza, dengue, leptospirosis, severe COVID-19 or bacterial sepsis. By the time the cardiopulmonary or oliguric phase is unmistakable, the therapeutic window has narrowed considerably.

Architecture flow diagram showing how the Kantesti Hantavirus Risk Assessment combines an interpreted blood test report with optional clinical context and emits a structured risk score
Figure 1: The reasoning service is anchored on an interpreted blood test report. Optional exposure, symptom and serology context refine the score without being required for it.

The clinical question we face in practice is not whether a given febrile patient has Hantavirus. It is whether the laboratory signature, the exposure context and the symptom profile together justify ordering Hantavirus serology now rather than reaching for a generic "viral syndrome" label and discharging on supportive care. That second question is where the diagnostic gap sits and where post-mortem case reports keep returning. We see a febrile patient. We see thrombocytopenia. We see a creatinine creep. We do not always remember to ask about rodent exposure, because the question itself is uncommon enough to slip the mind on a busy shift.

The Kantesti AI Hantavirus Risk Assessment exists to keep that question on the table. It is a clinician-facing decision-support module that lives inside the patient record beside the latest blood work. It reads the interpreted blood test report the broader Kantesti pipeline has already produced. It asks the clinician for whatever exposure, symptom and serology context is to hand and it returns a structured 0 to 100 risk score with a written rationale, a list of contributing factors, a list of red flags and an explicit declaration of what data it wishes it had.

As Thomas Klein, MD, I supervised the prodromal-signature weighting and reviewed the contributing-factor taxonomy on this module. The deliberate choice we made is to design for the prodromal window. The value of a triage tool that fires only when the cardiopulmonary phase is already obvious is close to zero. The clinical question is whether the engine can be useful 48 to 96 hours earlier. Our broader Medical Validation hub describes the framework. This page describes its applied result.

HPS versus HFRS at a glance

The two Hantavirus syndromes share a prodromal phase but diverge in dominant organ involvement, geography and reservoir. The table below summarises the differences that matter for triage. A clinician reading this on a febrile patient with rodent exposure should consider both, because early presentations are difficult to distinguish without serology.

HPS — Hantavirus Pulmonary Syndrome Americas · case-fatality 30–50% Sin Nombre virus (USA, Canada), Andes virus (South America). Cardiopulmonary phase with non-cardiogenic pulmonary oedema and shock.
HFRS — Hemorrhagic Fever with Renal Syndrome Eurasia · case-fatality 1–15% by serotype Hantaan, Seoul, Puumala, Dobrava-Belgrade. Five-phase course (febrile, hypotensive, oliguric, diuretic, convalescent). Acute kidney injury and hemorrhage.
Shared prodrome (both syndromes) 1–8 weeks incubation Fever, myalgia, headache, gastrointestinal symptoms. Thrombocytopenia, rising hematocrit, leukocytosis with immunoblasts.
Confirmation method (per CDC and WHO) IgM ELISA · RT-PCR Definitive diagnosis requires serology or molecular testing. Clinical assessment alone is insufficient for either syndrome.

The prodromal laboratory signature

A standard complete blood count and chemistry panel ordered for an undifferentiated febrile illness will, in early Hantavirus, often display a recognisable constellation. None of the findings is pathognomonic in isolation. Together, in the right exposure context, they form a probabilistic signature that pattern-recognition tools are well suited to surface.

Infographic of the Hantavirus prodromal laboratory signature including thrombocytopenia, rising hematocrit, leukocytosis with immunoblasts, modest transaminase elevation and creatinine creep
Figure 2: The prodromal laboratory signature. None of these findings is pathognomonic in isolation. Together, in a febrile patient with rodent or rural exposure, they raise the index of suspicion that triage tools are designed to capture.

Platelets are the most consistent abnormality. Thrombocytopenia, often dropping below 150 × 10⁹/L within the first 72 hours, is reported in 70 to 90 percent of HPS cases at presentation. Hematocrit rises secondary to capillary leak and plasma volume contraction. The white-cell count rises with a left shift and immunoblasts (sometimes called atypical lymphocytes or Hantavirus-associated mononuclear cells) appear on the peripheral smear. Lactate rises with tissue hypoperfusion. Transaminases (AST, ALT) and LDH rise modestly with cellular turnover. Creatinine begins to rise sharply in HFRS and more subtly in HPS.

Platelets Often < 150 × 10⁹/L Most consistent prodromal abnormality, present in 70 to 90 percent of HPS cases
Hematocrit Rising Hemoconcentration secondary to capillary leak and plasma volume contraction
White blood cells Leukocytosis with left shift Immunoblasts (atypical lymphocytes) on peripheral smear
Lactate Elevated Reflects early tissue hypoperfusion before frank shock
AST · ALT · LDH Modestly elevated Cellular turnover, generally not in the hepatitis range
Creatinine Rising Sharp rise in HFRS, subtler in HPS

The clinically reassuring property of this signature is that it sits inside an investigation any clinician will already have ordered. Nothing in the prodromal pattern requires a special test. The challenge is one of pattern recognition under cognitive load. A tired clinician on a busy shift looking at a thrombocytopenia and a mild creatinine creep in a febrile patient may reach for sepsis, viral hepatitis or atypical pneumonia long before reaching for Hantavirus serology. That is exactly the moment a calibrated decision-support layer earns its place.

How the module works, end to end

The module is a single-page sub-application inside the Kantesti clinic dashboard, invoked from the patient profile (with the patient auto-selected via deep-link) or from the dashboard's main navigation. It composes three layers: a clinician-facing UI, a reasoning service that calls a secure cloud-hosted large-language-model endpoint with strict JSON output and a per-clinic per-patient assessment store keyed for safe overwrite on language change.

Inputs

The reasoning is anchored on the interpreted blood test JSON that the broader Kantesti pipeline produces from raw laboratory uploads (PDF, photo or structured laboratory feed). This is the critical engineering decision. The AI is not asked to interpret raw numbers in a vacuum. It is given a structured already-curated report containing laboratory values with reference ranges, units and per-parameter clinical commentary, plus a prose interpretation of the panel. On top of that authoritative anchor the clinician may optionally add four blocks of context.

  1. Exposure history. Rodent contact, cleaning of closed or abandoned spaces, recent travel to endemic regions and days since presumed exposure.
  2. Symptom set. Fever, myalgia, dry cough, dyspnoea, gastrointestinal distress and headache.
  3. Vital signs. Peripheral oxygen saturation (SpO2), systolic blood pressure and heart rate.
  4. Hantavirus-specific testing. IgM (ELISA), IgG and RT-PCR, with an acute-phase status flag where available.

All optional sections are explicitly marked as optional. The design point is that missing data should not block scoring. Instead, the AI is required to declare what it is missing and how that missing data affects its confidence. This honesty requirement is enforced at the schema level rather than negotiated at runtime.

Output schema

Every reasoning call returns a strict JSON payload. The schema is what makes this system trustable in a clinical setting. A reviewer can audit any score by reading its contributing factors and red flags and challenge it where appropriate. The model is required to be explicit about what it does and does not know. Vague hand-waving is not in the contract.

risk_score integer 0 to 100 Calibrated risk that the presentation warrants Hantavirus workup
risk_level low / moderate / high / critical Clinical bucket derived from the score
confidence low / medium / high The model's self-reported certainty given the data on hand
recommended_action string A single actionable next step in the clinician's language
explanation string A clinically-readable rationale tying the score to the data
contributing_factors array Each factor names a finding, marks its direction (↑ or ↓ on risk) and assigns an impact
red_flags array Findings that should escalate management independent of the score
missing_critical_data array Data the model wishes it had, with a brief reason for each

All eight fields are required for every reasoning call. The UI renders each one without ever calling innerHTML on AI-derived strings. Every output token reaches the DOM through textContent or attribute assignment, which closes the obvious cross-site-scripting hole that AI outputs would otherwise open. Allow-listed enum values are validated before rendering. AI prose cannot inject markup.

A sample CRITICAL risk output

The screenshot below shows a real CRITICAL classification produced by the production module. The patient profile is a 26-year-old presenting with rodent exposure, recent cleaning of a closed space, fever, myalgia, cough, dyspnoea and SpO2 of 93 percent. The module returned a risk score of 82 out of 100 with moderate confidence and a recommendation to seek urgent in-person evaluation before pending laboratory results.

Application screenshot showing a CRITICAL Hantavirus risk classification of 82 out of 100 with red flags including SpO2 93 percent and dyspnoea
Figure 3: A real CRITICAL risk output produced by the production module. Score 82 of 100, confidence moderate, two red flags and seven contributing factors. The rationale traces directly to the inputs and is auditable line by line.

🔴 Sample case — anonymised input

Exposure context. Recent cleaning of a closed space with documented rodent activity. Patient reports peridomestic rodent contact in the preceding 14 days.

Symptoms. Fever, myalgia, dry cough, dyspnoea on minimal exertion. Mild gastrointestinal distress.

Vital signs. SpO2 93 percent on room air. Other vitals not reported by the referring clinician.

Laboratory. Interpreted blood test report not yet uploaded at the moment of assessment. Hantavirus-specific serology pending.

📋 Sample output — module response

Risk level. CRITICAL. Score 82 out of 100. Confidence moderate.

Recommended action. Seek urgent in-person medical evaluation now, before test results return.

Explanation. "This patient has significant Hantavirus-compatible exposure history plus fever, myalgia, cough, dyspnoea and oxygen saturation below 94 percent, which raises concern for serious disease. The symptom pattern and low SpO2 are concerning for possible early cardiopulmonary involvement. Risk remains uncertain because key laboratory data and test results are still pending."

Red flags. SpO2 93 percent. Dyspnoea.

Contributing factors. HIGH ↑ rodent exposure · HIGH ↑ cleaning a closed space · HIGH ↑ dyspnoea · HIGH ↑ SpO2 93 percent · MEDIUM ↑ fever and myalgia · MEDIUM ↑ cough · LOW ↑ GI symptoms · LOW ↓ age 26 years.

Missing critical data. Platelet count, hematocrit, white blood cell count, creatinine, AST, ALT, LDH, RT-PCR, IgM and IgG.

The clinical value of the explicit missing-data declaration deserves a moment of attention. The model is not pretending to know more than it does. It returned a CRITICAL classification on exposure context plus vital signs alone and stated openly that the picture would tighten with the pending laboratory work. A clinician reviewing this output knows immediately what data, once available, will change the score upward (a thrombocytopenia confirms the prodromal pattern) or move it downward (a normal IgM and a clean platelet count after 96 hours of symptoms argues against active Hantavirus). This is the architectural answer to the AI hallucination concern: every claim is structured in a way that makes uncertainty visible rather than hidden inside fluent prose.

Fifty thousand interpreted reports, three confirmed cases

Between 1 February and 8 May 2026 the Kantesti platform processed 50,000 consecutive interpreted blood test reports for which the Hantavirus Risk Assessment module was either explicitly invoked by a clinician or implicitly evaluated as part of the integrated risk-flag layer surfaced beside the standard interpretation. Reports originated from 127 countries across the Americas, Europe, the Middle East, Sub-Saharan Africa, South Asia, East Asia and Oceania.

Bar chart showing distribution of Hantavirus risk classifications across 50,000 interpreted reports with 46832 low, 3154 moderate, 11 high and 3 critical
Figure 4: Distribution of risk classifications across 50,000 interpreted reports (Feb to May 2026). Of 14 high or critical scores, three were laboratory-confirmed Hantavirus by IgM ELISA or RT-PCR.
Reports analysed 50,000 Feb to May 2026 · 127 countries
14 High or critical
3 Lab-confirmed
75+ Languages active
0.028% High/critical rate
Risk level Reports (n) Proportion Confirmed
Low46,83293.66%
Moderate3,1546.31%
High110.022%1 confirmed
Critical30.006%2 confirmed

The distribution is intentionally heavily skewed toward the low and moderate buckets. Hantavirus is uncommon globally and a triage tool that fired high on every febrile illness would be clinically useless. The module is calibrated to surface a high or critical risk only when the laboratory and clinical signature is genuinely consistent with the syndrome. The corresponding case-finding rate of approximately 6 confirmed Hantavirus infections per 100,000 interpreted reports is consistent with what would be expected of a globally rare condition surveilled through a non-targeted clinical workflow.

A few important caveats sit alongside these numbers. Confirmation status is only known where the partner clinic shared post-laboratory follow-up with the platform. The true number of Hantavirus cases in the cohort may be higher. The module is not designed to discriminate Hantavirus from the other syndromes in the prodromal differential (leptospirosis, dengue, severe COVID-19, atypical pneumonia and sepsis). The relevant clinical question is whether the patient warrants targeted Hantavirus workup, not whether they definitely have Hantavirus. The clinical value of a tool with a low base-rate denominator lies in catching the cases that would otherwise be missed during the prodrome.

What the three confirmed cases were called at presentation

All three laboratory-confirmed Hantavirus cases were initially classified by the presenting provider as one of: influenza-like illness, atypical community-acquired pneumonia or undifferentiated bacterial sepsis. None of the three had Hantavirus on the initial differential. The module elevated Hantavirus into consideration on the basis of the laboratory pattern and, where available, exposure history.

Editorial breakdown of three laboratory-confirmed Hantavirus cases showing initial misclassification as influenza-like illness, atypical pneumonia or bacterial sepsis
Figure 5: All three laboratory-confirmed Hantavirus cases were initially clinically misclassified as influenza-like illness, atypical pneumonia or bacterial sepsis. The module elevated Hantavirus on the basis of the prodromal laboratory signature plus exposure history.

Patient identities, geographic locations, age, sex, occupational exposure and clinical details are withheld in compliance with GDPR and HIPAA-aligned safeguards. We can disclose the following aggregate observations.

Common laboratory signature

All three confirmed cases displayed thrombocytopenia (platelets below the lower reference limit), at least two of (rising hematocrit, transaminase elevation, lactate elevation) and a left-shifted leukocytosis at presentation. These findings together are non-specific in isolation but jointly characteristic of the prodromal phase. The module assigned high or critical risk in each case and recommended urgent laboratory confirmation by IgM ELISA or RT-PCR.

Time to confirmation

Subsequent IgM ELISA or RT-PCR confirmation occurred between 24 and 96 hours after the module first surfaced a high or critical classification, in line with typical regional turnaround for confirmatory Hantavirus testing. In each case the formal Hantavirus workup was initiated as a direct response to the module's flag.

Outcomes

All three patients survived and progressed to clinical recovery. We make no causal claim that the module was responsible for these outcomes. Outcomes in Hantavirus depend on many factors including supportive care quality, severity at presentation and individual host response. The module's contribution was to surface Hantavirus as a differential consideration earlier than the clinician's pre-platform workflow would otherwise have done. Whether that earlier consideration changed disposition is a question we cannot answer from the available data.

As Thomas Klein, MD, I want to be careful here. Three confirmed cases do not constitute a randomised trial. They constitute a real-world signal in production traffic, with all the strengths and weaknesses that real-world data carries. The strength is that this is what happens when the module meets actual clinical workflow on actual patients in 127 countries. The weakness is that we do not have a counterfactual. We cannot say what would have happened to these patients without the module. What we can say is that the module performed exactly as designed: it pulled three Hantavirus presentations out of an unfiltered febrile-illness flow that had pattern-matched to the wrong differential at the bedside, and it did so on the basis of a structured rationale that the reviewing clinician could read and challenge.

More than 75 languages, no English fallback

A clinical decision support tool that only speaks one language is, by definition, an inequitable tool. Hantavirus is endemic across the Americas, Europe and East Asia. The patients who would benefit from earlier triage are not, on average, English-speaking. The module therefore localises into more than 75 languages, with native right-to-left rendering for Arabic, Hebrew and Persian, and with no English fallback anywhere in the rendering pipeline.

World map showing the more than 75 languages supported by the Kantesti Hantavirus Risk Assessment module
Figure 6: Language coverage. Hantavirus is endemic in regions where English is not the working language of clinical care. The module has no English fallback and renders fully in the active locale.

Languages currently shipping include English, Turkish, German, French, Spanish, Italian, Portuguese, Arabic, Hebrew, Greek, Polish, Dutch, Russian, Ukrainian, Chinese (Simplified), Chinese (Traditional), Japanese, Korean, Hindi, Bengali, Persian, Thai, Vietnamese, Indonesian, Malay, Tagalog, Swedish, Norwegian, Danish, Finnish, Czech, Slovak, Slovenian, Croatian, Bulgarian, Serbian, Latvian, Estonian, Lithuanian, Hungarian, Romanian, Albanian, Macedonian, Maltese, Icelandic, Irish, Welsh, Basque, Catalan, Galician, Afrikaans, Swahili, Amharic, Yoruba, Zulu, Urdu, Punjabi, Tamil, Telugu, Kannada, Malayalam, Sinhala, Nepali, Marathi, Gujarati, Khmer, Lao, Burmese, Mongolian, Kazakh, Uzbek, Azerbaijani, Armenian, Georgian and Pashto.

Engineering details that make the localisation trustable

No silent English fallback. If a translation key is missing for the active locale the build fails. We do not paper over a hole with English. A complete parallel string set is required for every page in every supported language. This is non-trivial engineering investment and it is the price of treating multilingual clinical AI as a first-class concern rather than as a marketing line.

Locale-aware caching. The Hantavirus assessment store keys on (clinic, patient, report, language) semantics. Switching the active language causes the next assessment to overwrite the prior row rather than serving a stale row in the wrong locale. A clinician can switch from English to German and the next score will arrive in German with no inconsistency.

Compound-word safety. German strings such as "Familien-/Patientengesundheit Risikoanalyse" are notoriously fond of breaking responsive layouts. The CSS uses overflow-wrap: anywhere, hyphens: auto and flex-wrap on plan cards so badges drop neatly to a new line on narrow viewports rather than escaping the card. Finnish, Hungarian and Greek receive the same treatment.

Right-to-left support. Arabic, Hebrew and Persian are detected on language change. The document direction is set. The CSS adapts mirror-aware spacing and icon orientation. Score gauges, contributing-factor arrows and timestamp ordering all respect the active reading direction.

Per-clinic isolation and cascade lifecycle

Healthcare software fails on the day a tenant boundary is crossed. The module's design treats per-clinic isolation and patient-data containment as primary requirements, on the same footing as clinical correctness.

Architectural diagram of the per-clinic per-patient assessment store showing UPSERT semantics and cascade hooks for patient and clinic deletion
Figure 7: Per-clinic isolation and cascade lifecycle. Every assessment row is keyed on the authenticated clinic identity. Deleting a patient or a clinic removes corresponding assessments. No orphaned rows accumulate.

A non-exhaustive list of safeguards in place, described at a level of abstraction that does not invite probing.

  • Authenticated session required. The module's endpoints are not reachable without a valid clinic session. There is no anonymous mode.
  • Per-clinic isolation. Every storage operation is keyed on the authenticated clinic identity. A clinician in Clinic A cannot see, list, view, regenerate or delete an assessment belonging to Clinic B by any combination of identifiers.
  • Path-traversal hardening. All filesystem references derived from request parameters pass component-level validation before canonicalisation, with rejection of separators, null bytes, parent-directory tokens and tilde expansion.
  • Cross-site-scripting safety on AI output. AI-generated strings are inserted into the DOM exclusively through textContent and attribute assignment, never innerHTML. Allow-listed enum values are validated before rendering.
  • Parameterised SQL throughout. No string-interpolated SQL touches the assessment store. All writes and reads use bound parameters.
  • Cascade lifecycle. Deleting a patient, deleting a clinic, regenerating a report or deleting a report all trigger explicit cascade hooks that remove or invalidate the corresponding Hantavirus assessments. No orphaned rows accumulate.
  • Compliance posture. Kantesti Ltd is GDPR-compliant for European data subjects, HIPAA-aligned for US healthcare partners and operates ISO 27001-aligned controls and SOC 2 Type II security practices. The platform holds CE marking for the European market.
  • Auditability. Every assessment row carries a hash of the source report, the language it was scored in and timestamps for create and update. A clinical reviewer can reconstruct exactly what input produced what output at what time.

We do not publish the specific filtering rules, request validators, regex patterns or attack vectors used during hardening. Advertising the test set advantages an attacker more than it reassures a clinician.

How clinicians and patients access the module

The Hantavirus Risk Assessment is freely available to every Kantesti user. The public-health value of catching Hantavirus earlier should not be a function of a clinic's billing tier, so the module is enabled on the consumer free tier, the single-report and 6-report bundles, the annual plan and every clinic dashboard plan from day one.

For clinicians

Sign in to the Kantesti clinic dashboard. Open a patient record. Click the Hantavirus Risk Assessment action from the patient profile, or open the dashboard's main navigation and pick the patient from the picker. Optionally fill the exposure, symptom, vital-sign and Hantavirus-specific testing sections. Submit. The module returns a structured score in the active dashboard language with full rationale, contributing factors, red flags and a missing-data declaration. Exports are available as a print-ready PDF for inclusion in the patient chart.

For patients

If you are reading this as a patient or family member with a recent blood test that you are concerned about, you can upload the report to the Kantesti consumer portal at kantesti.net/free-blood-test and request the Hantavirus Risk Assessment. The consumer-facing flow returns an interpretable risk band with explicit instructions to seek in-person clinical evaluation if the band is elevated. The module is decision support and is not a diagnostic device. Severe suspected cases warrant urgent care before laboratory confirmation.

For partner clinics and laboratories

If your clinic or laboratory routinely handles febrile-illness presentations in regions where Hantavirus is endemic and you would like the module surfaced inside your existing electronic health record workflow, please reach the team via kantesti.net/contact-us. We support deployment under the standard GDPR-compliant and HIPAA-aligned partnership agreement and run integration through a dedicated clinical engineering point of contact.

What the module is not

A short and deliberate inventory of what this tool does not do. We hold ourselves to a higher honesty standard than is typical for this category of product.

  • Not a diagnostic device. Definitive Hantavirus diagnosis requires laboratory confirmation through IgM serology by ELISA or molecular testing by RT-PCR, per CDC and WHO guidance. The module does not replace either.
  • Not a substitute for clinical judgement. Final clinical decisions remain with the qualified clinician. The module is one input among several, alongside history-taking, physical examination, alternative diagnoses and the clinician's local epidemiological knowledge.
  • Not a discriminator across the full prodromal differential. Many of the prodromal findings overlap with leptospirosis, dengue, severe COVID-19 and bacterial sepsis. The module is a triage aid for Hantavirus risk specifically. It does not rank Hantavirus against the other syndromes in the differential.
  • Not regulatorily classified as a medical device. The module is offered as clinical decision support. It is not classified as a medical device under EU MDR or FDA regulation. Clinics deploying the platform must comply with their own jurisdiction's regulatory regime for the use of decision support in patient care.
  • Not a sensitivity or specificity claim. The 3 confirmed cases reported from 50,000 interpreted reports reflect cases where partner clinics returned subsequent laboratory confirmation status to the platform. We make no formal claim about sensitivity or specificity in the epidemiological sense.
  • Not population-specific for paediatrics or pregnancy. Hantavirus in paediatric and pregnant patients carries additional considerations. The module does not currently produce population-specific weightings beyond what the AI infers from the demographic fields. Explicit citable prior weighting for these subgroups is on the roadmap.