Spread from rodents to humans, old and new world Hantavirus has become endemic in many continents, but are sporadic cases of person-to-person transmission strong enough evidence to fear its pandemic potential?

In April 1993, concerns of a mysterious plague outbreak shook the Native American region bordering Utah, Colorado, Arizona and New Mexico. After the mysterious deaths of a young Navajo couple in New Mexico, state officials struggled to identify the cause, but were able to link symptoms to a dozen more cases in this region. It was later discovered that a novel species of hantavirus had emerged, known as Sin Nombre Virus (Spanish for "No name"), which eventually claimed the lives of 13 people. This outbreak is now known as the "1993 Four Corners outbreak" and has raised concern about the evolution of hantaviruses.

Orthohantaviruses are a viral genus which are able to cause disease in humans. These are transmitted through inhalation of aerosols from infected rodent excretions and cause a range of haemorrhagic and pneumonic symptoms. Particular species such as Hantaan orthohantavirus and Dobrava-Belgrade orthohantavirus have most likely been circulating in regions of the world for centuries, while Sin Nombre virus and Andes virus species were isolated in the 1990s. This distinction between old and new world viruses is significant regarding morbidity and mortality as well as their potential to become pandemic. Human-to-human transmission of hantavirus is very rare, but even so epidemics remain a public health concern, particularly because of the risk of household infections and nosocomial spread, where transmission occurs within hospitals and clinics.