On May 19 over 540 saiga antelope (Saiga tatarica), one of the rarest mammals on the planet, were found dead in northern Kazakhstan’s Qostanai region. Another die-off exceeding 400 saiga was discovered just days later in the Zhangeldin region, southwest of Qostanai. A majority of those found dead have been females. This finding is likely due to nutritional stress leading to a higher susceptibility to infection after giving birth to calves.
Die-offs have affected endangered saiga populations before. In the late 1960s deaths of saiga in Kazakhstan reportedly occurred due to foot-and-mouth disease (FMD), while pasteurellosis was suspected in an outbreak that killed nearly 450 in May 2011. The largest die-off to date occurred in 2010, when an estimated 12,000 saiga were found dead. The cause of the 2010 event was determined to have been a combination of factors including ingestion of toxic plants, a change in diet causing bloating, diarrhea, and a respiratory-based sudden death syndrome similar to fog fever.
Once numbering in the millions, saiga are currently listed as critically endangered according to the International Union for Conservation of Nature (IUCN) Red List. Unregulated hunting, primarily after the collapse of the Soviet Union, led to a massive decrease in saiga populations. Horns of the male saiga are used in traditional Chinese medicine as painkillers and antibiotics. Poaching of males was on such a massive scale that the ratio of males to females was depleted to 1 to 100, thereby dramatically affecting reproduction rates. Poaching, severe winters, drought, and naturally occurring disease die-offs have all contributed to the saiga’s decline, with the total population now estimated to be near 50,000.
As conservationists try to increase saiga population numbers, preliminary results list pasteurellosis as the likely cause of this most recent die-off. Pasteurellosis is caused by infection from bacteria of the genus Pasteurella. Pasteurellosis can be rapidly fatal. It causes numerous pathological conditions in domestic animals, and often acts together with other infectious agents. In cattle and other ruminants, symptoms include sudden onset of high fever, salivation, and pneumonia. Infection in humans may occur following bites, scratches, or licks from an infected animal. Symptoms in humans include local wound infection, swelling, and cellulitis. Rarely, the organism infects the respiratory tract leading to ear infection or sinusitis. Pasteurellosis in humans can be treated with antibiotics. Unfortunately, treatment of infection in wild animal populations is difficult, particularly in remote locations, and in situations with rapid onset of illness.