Andes hantavirus strain found in Hondius cases, South Africa's health ministry confirms
South Africa's health ministry has confirmed that two cases linked to the MV Hondius outbreak were caused by the Andes strain of hantavirus. The ministry said laboratory testing carried out at the National Institute for Communicable Diseases (NICD) in Pretoria definitively identified the strain.
The ship had called at South African ports earlier in its itinerary, returning from an Antarctic season, which placed the country's epidemiological surveillance system on alert. NICD's confirmation reinforces the suspected Patagonian source of the outbreak. The Andes strain is primarily carried by the long-tailed pygmy rice rat, found in the Patagonian regions of Chile and Argentina.
A ministry spokesperson told the BBC: "Our results will be cross-checked with the World Health Organization and the European Centre for Disease Prevention and Control." Samples have also been sent to a reference laboratory in Chile that handles Andes-strain work. The ministry said additional confirmatory testing will support the official genomic record.
The Andes strain is the only hantavirus variant where human-to-human transmission has been documented. Even within its endemic geography, such transmission remains rare. One of the most-cited examples in public-health literature is a 1996 outbreak in El Bolsón, Argentina, where about 20 people were infected.
In analysing the shipboard cases, NICD said genome-sequencing data closely matched known Andes-strain variants. Sequencing can help identify the specific origin within the strain's range, and results from that work are expected in the coming days. NICD will publish the data once peer-reviewed.
The ministry's announcement came after the WHO statement regarding three deaths over the course of the voyage. The WHO said two of the confirmed cases on board came from human-to-human transmission and described the development as "infrequent." NICD's confirmation now provides a scientific basis for that strain identification.
South African local health authorities have applied a 14-day observation window for passengers arriving at the country's northern ports. There are no known active local cases; the ministry said the virus is not present in South Africa and that strict monitoring continues for surveillance purposes only.
The clinical presentation of Andes-strain infection includes fever, muscle aches, headache and vomiting; 35 to 40 percent of cases can progress to hantavirus pulmonary syndrome. NICD clinicians said there is no approved antiviral therapy targeted at this strain, but early supportive care substantially increases the chance of survival.
Experts say the confirmation of human-to-human transmission is an important global signal. The ECDC and CDC have begun reviewing border-crossing protocols and national notification rules. NICD said it will make data available to international research teams to support the broader surveillance effort.
South Africa has also said its 2026 budget includes a dedicated line item to strengthen the country's epidemiological capacity. The ministry pointed to NICD's status as a leading laboratory on the African continent and said it intended to keep that international reference role going forward.