EPIDEMIOLOGY: VS occurs in North and South America, Africa and Asia, but not in central Europe (6). Serological studies indicate that the prevalence of infection may be high in some populations in enzootic areas. For is telegram available in south korea example, in a rural locality in Panama, more than 90% of the adult population is affected (3); however, the precise frequency of VS is not well established, as the disease often goes unnoticed due to its benign course.

HOST RANGE: Humans (1,2,4,5,6,8), horses (2,4,6,8), cattle, pigs, mules (2,6), sand flies (5,6), grasshoppers (4) and rodents (2).
INFECTIOUS DOSE: Unknown.
MODE OF TRANSMISSION: Bite of an infected sand fly(1,5,7,8); by direct contact with skin abrasions; by contact with infected domestic animals; or by inhalation of aerosols via the nasopharyngeal route(1,3). The virus has also been transmitted by accidental self-inoculation or inhalation of aerosols in a laboratory(3,8).
INCUBATION PERIOD: A wide range of incubation periods has been reported from 30 hours(1,6) to 6 days(7).