Several recent cases of large numbers of Caspian seals dying due to canine distemper virus have been reported, in 1997, 2000, and 2001. In April 2000, a mass die-off of Caspian seals was first reported near the mouth of the Ural River in Kazakhstan. It spread south to the Mangistau region, and by the end of May, more than 10,000 seals had died along the Kazakhstan coast. High death rates were also recorded in May and June along the Apsheron peninsula of Azerbaijan and the Turkmenistan coast.