Snakebit: Surviving the Black Mamba

African governments and the WHO combat continent's snake bite problem.

February 18, 2009, 9:17 PM

NAIROBI, Apr. 2, 2008— -- In the action movie "Kill Bill" the lead character goes by a nickname, "Black Mamba." She's a killer: She strikes quickly and fatally — just like her namesake the black mamba snake, the most feared snake in Africa.

The mamba is found throughout most countries in Sub-Saharan Africa and is incredibly fast, traveling at speeds up to 12 miles per hour. It's also large; the second largest snake in Africa, and aggressive and territorial, characteristics not usually attributed to snakes.

The black mamba actually isn't the most deadly snake on the continent; that honor belongs to the Puff Adder Viper, which is also the most common poisonous snake in Africa and has the most contact with humans.

But villagers and experts alike fear the intense pain and suffering the mamba inflicts on its victims. Its poison is neuro-toxic. Unlike most poisonous snakes where the venom travels slowly through the blood stream, allowing a victim time to get treatment and to isolate the poison using a tourniquet, the black mamba's poison goes straight for the nerves, attacking the central nervous system and shutting down major organs. Twenty minutes after being bitten you may be lose the ability to talk. After one hour you're probably comatose, and by six hours, without an antidote, you are dead.

A person will experience "pain, paralysis and then death within six hours," says Damaris Rotich, the curator for the snake park in Nairobi. "The kind of experience that the person goes through is really horrible."

A trained biologist, Rotich has studied the complex effects of snake bites on humans, including the black mamba.

In Kenya, Rotich says it's hard to keep official statistics of how many humans die of snake bites each year, but it's estimated that the number is in the tens of thousands. The problem became so severe that the Ministry of Health along with the World Health Organization launched a country-wide campaign five years ago to educate people about snake bites.

In rural villages where people are more likely to be bitten, Rotich says education was needed to make villagers understand that traditional, home remedies were not effective, particularly in the case of the black mamba.

"There are people who believe that mambas feed on cow milk so they actually go to cow sheds to actually suckle milk to treat the bite," she says. "But if one has been bitten and venom has been injected and no medical intervention, such as administering the anti-venom, is done quickly, for sure that person will die."

Snake anti-venom works much like a vaccine, says Dr. Mercy Njuguna, the marketing manager for Sanofi Pasteur, a French pharmaceutical company that manufactures snake anti-venom for primarily Africa.

"You need the snake to make the anti-venom" she says.

For years each type of snake had its own anti-venom, but health care workers often had problems identifying what type of snake had bitten a victim, leading to precious lag time between the bite and administering the serum, or worse administering the wrong one. In response pharmaceutical companies have developed an all-in-one anti-venom serum for the region.

The anti-venom now administered counteracts bites from Africa's 10 most poisonous snakes, including the mamba. "We have 10 anti-venoms in one," says Njuguna. "It saves time and lives."

But the process to make the anti-venom serum is a long and cumbersome one.

It starts with snake farmers who are employed by pharmaceutical companies to "milk" the venom from a snake — getting the snake to phantom bite and extracting the venom, referred to as "harvesting" the poison. Then a small dose is injected into a horse.

Horses work well because they have a lot of blood volume, says Dr. Njuguna.

"Small amounts of the venom can be injected without hurting the horse," she says. "It's how many vaccines and serums are made."

But all 10 venoms cannot be injected at once. At least three months between every two injections is needed.

Once the horse has all the injections, its blood containing the 10 anti-bodies is extracted. According to Dr. Njuguna, the blood must then be purified and pasteurized before it can be given to human beings. That way, she says, "you only get the 'FAB,' or fragment antigen binding," meaning that the serum will be pure and won't be rejected by the human body.

After that, the serum is actually tested on humans at a snake bite center. Most are located in West Africa, which has the most serious bite problem. It can take more than a year to produce just one dosage.

Even with the long and careful serum process, people still have serious allergic reactions to the anti-venom, says Njuguna. Some experience have immediate anaphylaxis, in which their bodies reject the anti-venom outright and they go into shock. That reaction is rare, but as precaution clinics that treat snake bites also have adrenaline on hand to counteract any allergic reaction.

The most common allergic reaction is referred to as "serum sickness," in which a person feels ill several days after taking the serum.

One of the ways health care workers are taught to reduce reactions is by diluting the serum with saline before administering it. But the black mamba is so deadly that it is recommended that the anti-venom be injected directly into the bloodstream — and fast.

The anti-venom "neutralizes the venom immediately," says Njuguna. "With Mamba poisoning you're racing against time."

The horrible effects of the venom make any allergic reaction worth the risk. In fact, with black mamba bites even children are given the full anti-venom dose, says Njuguna. It's even more important in children because the poison spreads much quicker through the body.

Putting the anti-venom serum in rural hospitals and clinics is costly. After being bitten, a person needs two doses of the serum, and each dose costs around $200 — an enormous amount of money for countries where the majority of the rural population survives on little more than a dollar a day.

Also, the venom has a shelf life of no more than three years, meaning that if it's been a "good year" for snake bites, the serum won't be used and could get tossed out.

By 2000, pharmaceutical companies had almost stopped manufacturing snake anti-venom serums because of a lack of orders. But once the WHO decided to address snake bites as a public health issue in Africa, governments followed. And the development of the 10-in-one serum cut costs dramatically.

Kenya, in particular, has decided to tackle the problem head-on. Besides the ongoing educational campaign, the Kenyan government continues to underwrite the costs of stocking and administering the serum throughout the country.

"The government ordered 27,000 doses this year," says Dr. Njuguna.

More anti-venom clinics are being opened throughout Africa, as health experts and governments across the continent continue to believe that while the serum may be costly and complicated to produce, the price of not having it available is much higher.