Mad, bad and dangerous to know: the biochemistry, ecology and evolution of slow loris venom

Anaphylactic shock following the bite of a wild Kayan slow loris (Nycticebus kayan): implications for slow loris conservation

Background

Asian slow lorises (Nycticebus spp.) are one of few known venomous mammals, yet until now only one published case report has documented the impact of their venomous bite on humans. We describe the reaction of a patient to the bite of a subadult Nycticebus kayan, which occurred in the Mulu District of Sarawak in 2012.

Findings

Within minutes of the bite, the patient experienced paraesthesia in the right side of the jaw, ear and right foot. By 40 minutes, swelling of the face was pronounced. The patient was admitted to Mulu National Park Health Clinic/Klinik Kesihatan Taman Mulu Tarikh, at which time he was experiencing: swollen mouth, chest pain, mild abdominal pain, nausea, numbness of the lips and mouth, shortness of breath, weakness, agitation and the sensation of pressure in the ears due to swelling. The blood pressure was 110/76, the heart ratio was 116 and oxygen saturation was 96%. The patient was treated intramuscularly with adrenaline (0.5 mL), followed by intravenous injection of hydrocortisone (400 mg) and then intravenous fluid therapy of normal saline (500 mg). By 8 h10 the next day, the patient’s condition had significantly improved with no nausea, and with blood pressure and pulse rate stable.

Conclusions

A handful of anecdotes further support the real danger that slow loris bites pose to humans. As the illegal pet trade is a major factor in the decline of these threatened species, we hope that by reporting on the danger of handling these animals it may help to reduce their desirability as a pet.

Tracing monotreme venom evolution in the genomics era

The monotremes (platypuses and echidnas) represent one of only four extant venomous mammalian lineages. Until recently, monotreme venom was poorly understood. However, the availability of the platypus genome and increasingly sophisticated genomic tools has allowed us to characterize platypus toxins, and provides a means of reconstructing the evolutionary history of monotreme venom. Here we review the physiology of platypus and echidna crural (venom) systems as well as pharmacological and genomic studies of monotreme toxins. Further, we synthesize current ideas about the evolution of the venom system, which in the platypus is likely to have been retained from a venomous ancestor, whilst being lost in the echidnas. We also outline several research directions and outstanding questions that would be productive to address in future research. An improved characterization of mammalian venoms will not only yield new toxins with potential therapeutic uses, but will also aid in our understanding of the way that this unusual trait evolves.