What clinicians actually order when they suspect hantavirus pulmonary syndrome, how PCR and serology differ, and how the same diagnostic stack has been used to investigate the 2026 MV Hondius cluster.
There are two blood tests for hantavirus and they answer different questions. A PCR test looks for the virus's genetic material in your blood and tells you whether you have an active infection right now. A serology test looks for IgM and IgG antibodies your immune system has made against the virus, and tells you whether you have ever been exposed. Both are sent out to a public-health or reference laboratory; there is no FDA-cleared at-home or rapid bedside test for hantavirus as of May 2026.
A hantavirus blood test draws the same volumes as any other infectious disease workup. PCR requires whole blood in an EDTA tube (lavender top) so that nucleic acid can be extracted without clotting interference. Serology requires a clotted serum tube (red or gold top) so that antibodies can be measured in the cell-free fraction. Most reference laboratories request both at once during an acute presentation, so the practical experience for the patient is a single venipuncture with two small tubes filled in sequence.
Hantavirus reverse-transcription PCR (RT-PCR) targets conserved regions of the small (S) or large (L) RNA segment of the virus. The test is highly specific — a clean positive result is rarely a false positive — and is the standard against which all confirmed cases in the 2026 MV Hondius cluster have been counted. PCR sensitivity is highest during the prodromal and early cardiopulmonary phases, when viral load is at its peak in plasma. Sensitivity drops as the body clears the virus over the following one to two weeks. This is why the WHO 42-day monitoring window pairs PCR testing at symptom onset with serology several weeks later, to catch infections in either window.
IgM antibodies appear in the bloodstream within roughly four to seven days of symptom onset and persist for two to three months. IgG appears a few days behind IgM and persists for years. A positive IgM with a rising paired-sample IgG is the textbook serological signature of recent infection. A positive IgG alone, with no IgM, points to old infection or vaccine response (relevant for the licensed Korean Hantavax against HFRS strains, not Andes virus). Reference laboratories use either ELISA-based immunoassays or strip-blot Western confirmation, depending on the strain panel and the country.
Every confirmed case in the 2026 MV Hondius cluster has been confirmed by PCR. The National Institute for Communicable Diseases (NICD) in South Africa ran the initial confirmation, and reference laboratories at Geneva University Hospitals, the Pasteur Institute in Paris, the Spanish Carlos III Institute, the Bernhard Nocht Institute in Hamburg, and the US CDC have run subsequent samples. The WHO shipped 2,500 hantavirus diagnostic kits from Argentina — the country with the deepest operational experience — to laboratories in five receiving countries to standardise the platform. Serology has been used as a back-stop for inconclusive PCR results and is expected to be central to seroprevalence analyses among MV Hondius contacts over the coming months.
Most reference laboratories return a PCR result within 24 to 72 hours of sample arrival. Urgent cases — a hospitalised patient on supplemental oxygen with a credible exposure — can be returned same-day if the sample reaches the laboratory by mid-morning. CDC confirmatory testing for suspected North American hantaviruses (such as the unrelated Sin Nombre case currently under investigation in Winnebago County, Illinois) typically takes up to ten days because it includes an independent second-laboratory confirmation step. Serology turnaround is generally three to seven working days.
Hantavirus PCR is very accurate when performed at a reference laboratory on a well-collected sample. The main practical pitfalls are timing (a sample drawn before viraemia is detectable can be falsely negative) and degradation in transit (haemolysed or warm samples can perform worse). Where there is a strong clinical suspicion and a negative early PCR, the right move is a repeat PCR 24 to 48 hours later. The American MV Hondius passenger in the Nebraska National Quarantine Unit whose result moved from positive to negative on retest is an example of this dynamic at work; the second sample, drawn after a clinical re-evaluation, was negative.
The absence of a rapid point-of-care or at-home hantavirus test is widely seen as the biggest preparedness gap that the 2026 cluster has exposed. There is no biological reason a lateral-flow assay for Andes virus could not exist; the obstacle is regulatory and commercial, since the global market for such a test in any given year is small. The WHO emergency scientific consultation on Andes virus medical countermeasures research and development on May 15, 2026 in Geneva is expected to discuss what regulatory and procurement levers would accelerate at least one rapid test through approval.
→ See the live MV Hondius tracker, 14-day timeline, and all 15 hantavirus news sourcesThe two main blood tests for hantavirus are PCR (which detects the virus's RNA in blood during active infection) and serology (which detects IgM and IgG antibodies the immune system has made against the virus). PCR is used early in symptomatic illness; serology is used to confirm exposure or document recent infection. Both are typically run at state public-health labs or reference labs like the CDC, the NICD in South Africa, or the Pasteur in France.
PCR turnaround at a reference lab is typically 24 to 72 hours from sample arrival, though urgent results for hospitalised patients can be returned same-day. CDC confirmatory testing for North American hantaviruses (such as Sin Nombre virus) usually takes up to ten days. Antibody serology takes 3 to 7 working days at most reference labs.
No. There is no FDA-cleared at-home or rapid point-of-care hantavirus test as of May 2026. All current diagnostic testing requires a clinical specimen drawn into a standard EDTA or serum tube and run at a public-health or reference laboratory. The absence of a rapid bedside test is one of the priorities being discussed at the WHO emergency scientific consultation on Andes virus countermeasures in Geneva.
Hantavirus PCR is highly specific and reasonably sensitive when the patient is symptomatic and viraemic. False negatives are possible very early in the prodromal phase, before viral load reaches the assay's detection threshold. False positives are uncommon but can occur at very low cycle thresholds; this is why public-health authorities sometimes retest an unexpectedly positive result before adding the case to the official count.
Testing is appropriate for anyone with fever, severe muscle pain, or unexplained shortness of breath who has had recent rodent exposure, has travelled in an endemic area (southern Argentina, Chile, southwestern United States, parts of Asia and Europe), or has been in close contact with a confirmed case. In the context of the 2026 MV Hondius cluster, all repatriated passengers are being tested for any new febrile or respiratory illness during the 42-day monitoring window.
Yes. IgG serology can confirm prior exposure for months to years after recovery, which matters for epidemiology, retrospective contact tracing, and seroprevalence surveys. Most laboratory experience suggests Andes virus IgG titres persist for at least several years after infection.