Bungarus

The genus *Bungarus*, commonly known as kraits, consists of highly venomous snakes. They belong to the family Elapidae. These snakes are found across much of Asia. They live in tropical and subtropical regions of South and Southeast Asia. Their range extends from Iran in the west to Southeast Asia in the east. This includes many countries like India, Thailand, Vietnam, and Indonesia.

Kraits are specialized predators with a unique lifestyle. They are nocturnal, meaning they are most active at night. They are also ophiophagous, which means they primarily hunt and eat other snakes. Occasionally, they will prey on lizards, amphibians, or small rodents. Because they hunt at night, they are seldom seen during the day. They become highly alert once the sun goes down.

Physically, kraits have several distinct features. Most species have smooth, glossy scales. These scales often form bold, striped patterns of alternating black and light colors. This is known as aposematic coloration, a warning signal to predators. The scales along the dorsal ridge, or the top of the back, are hexagonal. Their heads are slender, and their eyes have round pupils. Many kraits also have a shape called dorsolateral flattening, making them look triangular in cross section.

While most kraits stay within a medium size, some can grow quite large. Most species do not exceed a certain total length, but some specimens are much bigger. For example, the banded krait (*B. fasciatus*) can grow as large as 1.5 meters. The genus is diverse, currently holding 18 species and 5 subspecies. Different species live in different habitats, such as the many-banded krait in Taiwan or the blue krait in Cambodia and Indonesia.

The venom of a krait is medically significant and highly potent. It is a neurotoxic venom, meaning it targets the nervous system. Specifically, the venom contains presynaptic neurotoxins. These toxins affect how neuron endings release chemicals to communicate with the next neuron. When a person is envenomated, the toxins first block transmitter release. This causes a brief period of paralysis. This is often followed by massive overexcitation, which causes cramps, tremors, and spasms. Eventually, the symptoms taper off into full paralysis.

Because kraits are nocturnal, bites often happen after sunset. A dangerous aspect is that bites are often initially painless. This can lead to false reassurance or a victim not noticing the bite while sleeping. If a bite is not treated, it can lead to respiratory failure. This happens because the diaphragm becomes paralyzed, making it impossible to breathe. Death can occur about 6 to 12 hours after a bite, though it can be delayed. Mortality rates vary greatly by species. The common krait has a mortality rate of 70–80% if untreated. In contrast, the banded krait has a mortality rate of only 1–10% in untreated humans.

Medical treatment is critical for anyone bitten by a krait. Doctors may use antivenom to neutralize the toxins. For some species, polyvalent elapid antivenom is effective. In some cases, doctors may use cholinesterase inhibitors like physostigmine or neostigmine. These medicines can help because the toxins alter acetylcholine transmission. Even with medical help, patients may need mechanical ventilators to help them breathe. This is because the venom can cause complete muscle paralysis.