Four South American hemorrhagic fevers caused by arenaviruses have emerged in the last 5 decades. Hantavirus infections have been increasingly recognized in South America since the description in 1993 of Hantavirus pulmonary syndrome. Given the diversity of rodent species in the region, it can be foreseen that many other viruses will be discovered, and some of them will be causing human illnesses of high public health impact. In contrast, DA or TO subgroup strains cause an early nonfatal polioencephalomyelitis. TMEV is thought to be an excellent animal model for the human demyelinating disease, multiple sclerosis.
Data suggest that macrophages are a major reservoir harboring the virus.
In addition, TMEV can be used as a vector for delivering foreign sequences into the central nervous system. Hantaviruses include serious human pathogens that are maintained in nature in persistently infected rodents and that can also persistently infect cultured mammalian cells, causing little or no cytopathology. The mechanisms of hantavirus persistence are only beginning to be explored. Recent data point to subtle changes in the viral genome that might result in the differential regulation of replication and lead to persistence.