Chapter 4

Venomous Vipers, Irritating Insects and Deadly Bacteria

MANY PEOPLE HAVE FEARS of snakes or spiders or other creatures. Are these fears unfounded or rational? Depending on your fear of poison and your risk-taking sense, you might understand these anxieties. Many creatures, including various species of snakes, insects, spiders, fish and amphibians, produce poisonous substances, either as a means of disabling their prey and/or as a defence mechanism (see Appendix II). Many of them produce venom, which can result in little more than localised pain and a small area of swelling in humans; however, some venoms may have a general but more profound effect on the whole body, which, in certain circumstances, even prove to be lethal.

Algae and bacteria may be microscopic in size, but they can also produce potent poisons with dire effects. These tiny killers have caused many fatalities in the past.

Various snake venoms

There are about 3000 species of snake, but most of them are non-venomous. They kill their prey by constriction, as the boa constrictor does, or by engulfing the prey and then swallowing it whole. However, there are three families of front-fanged snakes that are venomous.

The first of these, the elapids, includes cobras, mambas, kraits, coral snakes and some Australasian land snakes. These snakes’ venom tends to cause neurotoxicity by affecting the nervous system. This group includes the Black Mamba, a very aggressive snake whose bite can kill a person within about four hours. More serious still is the Green Mamba, whose bite can be fatal within half an hour because its venom is so toxic. The most venomous snake in the world is thought to be the Inland Taipan (also known as the fierce snake) from central Australia. This snake produces the most toxic venom on the planet, and each bite contains enough venom to kill up to 100 people.

The vipers belong to a second family of snakes, and their bites tend to be vasculotoxic; that is, they affect the circulation. The Carpet Viper is widespread, found from West Africa to India. It is less toxic than the taipan but is more dangerous as it kills more people than any other species. Its venom rapidly affects the body’s blood-clotting mechanism, which can lead to septicaemia and organ failure.

Cleopatra, Queen of Egypt, is said to have committed suicide by allowing an asp viper to bite her breast, rather than be shamed following her army’s defeat at the Battle of Actium in 31 BC by Octavian the Emperor. Cleopatra’s asp was probably a horned viper.

The sea snakes belong to the third family of venomous snakes, and their bites are of the myotoxic type, with the venom affecting the muscles.

Depending on the type of snake venom, the effects of the venom may involve one or more of the body’s systems – sensory, motor, cardiac, renal or respiratory. Snake venom can cause a massive drop in blood pressure due to relaxation of blood vessel walls (vasodilatation), and this may affect the heart. There may also be local swelling around the area of the bite or puncture site, as well as bleeding from the gums. Additionally, there is a risk of the life-threatening allergic reaction anaphylaxis. In the United Kingdom, this extreme reaction by the body to an allergen is more commonly experienced from the sting of the wasps and bees described in the next section.

India’s snakes are said to be the most deadly in the world, killing over 50,000 people every year. Fortunately in Britain we have only one venomous snake, the Adder, whose bite is not usually very serious.

Insects and spiders

Insects in the United Kingdom are relatively harmless; however, the stings of wasps and bees do contain venom, and some people are allergic to it. Stings introduce poisonous substances into the body, causing local pain and swelling. Sometimes there are also systemic effects, which may be life threatening. Insect stings, particularly in the mouth or on the tongue, can cause local swelling, which may be severe enough to threaten the upper airway. This should always be treated as a medical emergency. Because of this danger, bees and wasps are probably the most dangerous venomous creatures in the world. Thousands of people around the world are killed by these insects each year.

While many species of spider are venomous, only a few of them are dangerous to humans. Spiders indigenous to the UK are non-poisonous, as their bite is too weak to break our skin. This is not the case elsewhere in the world, and some foreign insects and spiders, which can bite or sting us, are arriving as ‘stowaways’ in goods imported into the UK. Some of these foreign spiders are taking up residence since, because of climate change, they are able to acclimatise to living here.

The bites of the American Black Widow Spider, its relative the Red Back Spider, the Australian Funnel-Web Spider and the South American Banana Spider can all have a neurotoxic effect causing severe pain, headache, vomiting, raised blood pressure and heart rate, muscle spasms and sometimes coma. This type of bite can be treated by injection of antisera, in addition to other symptomatic treatment.

Other spiders such as the Brown Recluse Spider can also give a nasty bite. This bite has a necrotoxic effect, with local pain and swelling, which can be extensive and results in necrosis (death of the tissues) with a black eschar, or scab, forming. When the scab eventually comes off several weeks later, it leaves behind an ulcer that heals very slowly. In rare cases, the symptoms of such a bite can be life threatening. Antisera are also available for this necrotoxic type of spider bite, but they have been found to be rather less effective than those used for the neurotoxic type.

Marine creatures and Amphibia

There are only a few marine creatures in UK waters that sting: severe pain is the main symptom caused by Weever Fish as is the case with Jellyfish and Portuguese Man-O’-War. The most venomous creature in the world is considered to be the Australian Box Jellyfish or Sea Wasp. Each one contains enough poison to kill 60 people in as little as four minutes.

The popular first aid remedy of urinating on jellyfish stings has a basis in fact. One medical treatment involves dilute acetic acid (or more commonly, vinegar), so urine, which is sterile, slightly acidic and at body temperature, is a good, instantly available substitute.

Marine snails such as Conus geographus produce a mixture of conotoxins. These are polypeptides that act in various ways so that their combined effect produces total muscle paralysis. The sea snails inject these conotoxins into their prey by means of a hollow harpoon-like tooth. There have been occasional fatalities recorded, sometimes of swimmers, but more often of beach-combing shell collectors who received an injection from within their bucket of collected shells. So do take care! Fortunately for us, these dangerous creatures tend to live far away in the sub-tropical seas near Indonesia.

The Stonefish, found in both the Indian and Pacific Oceans, is the world’s most venomous fish. It hides in shallow coastal waters and coral reefs and, if stepped on, erects the spines on its back. These act like hypodermic needles, injecting poison into the wound. This is agonisingly painful and can lead to death within six hours. Although such deaths are rare, stonefish stings can lead to amputation of the affected limb.

The Puffer fish, also called the globefish, and some of its relatives, including the Porcupine fish, all produce a deadly neurotoxin called tetrodotoxin. It is said to be 1,000 times more deadly than cyanide. Every year, a number of people in the USA are poisoned as a result of eating puffer fish. This is also the case in Japan, where it is regarded as a great culinary delicacy. The chef must be trained in the preparation and cooking of the puffer fish and must hold a licence before the item can be included on the menu because of its extremely poisonous nature.

The poisonous nature of the puffer fish was known to both the ancient Egyptians and the Chinese over 2000 years ago. It is now known that tetrodotoxin and related poisons are quite widely distributed in nature, having also been found in a number of species of newts, frogs, lugworms and crabs. This wide distribution suggests that this neurotoxin is produced by a small organism at the bottom of the food chain and then simply accumulated and stored by the larger creatures, who are immune to its effects.

Some species of frogs, newts and toads, even in the United Kingdom, produce a variety of toxins, secreting them through their skin, but usually only as a defence mechanism. The Californian Newt is just one example that, like the puffer fish, produces tetrodotoxin. Some species of South American frog only secrete their poison when placed under stress, as a defence mechanism, which the local natives have used for centuries as very effective arrow poison.

The various species of the phyllobates genus of frogs living in Panama, Costa Rica and Columbia produce the toxin batrachotoxin, which is about five times as potent as tetrodotoxin. Other species of frogs have been found to produce many different types of related toxins. These toxins all seem to affect the nervous system in a variety of ways.

Algal toxins

In the Caribbean and around the Hawaiian islands certain seaweeds are prevalent and produce a poison called palytoxin, which was traditionally used by natives as an extract to smear onto their spears for hunting and warfare.

Palytoxin was first isolated in 1968, and when its chemical structure was finally worked out, it was found to be very complex. Although it is neither a carbohydrate nor a protein, it is one of the most toxic substances of marine origin yet found. This very potent toxin acts by paralysing all tissues: heart muscle, skeletal muscle, smooth or involuntary muscle and nerves, in addition to causing the rupture of red blood cells. These effects are all caused by disrupting the normal controls of the cell membranes, throughout the body, with disastrous consequences. For more details see Appendix IV.

Some algae, including the dinoflagellate plankton, produce brevetoxins or other related toxins. Every year, more than 20,000 people are poisoned, usually while on holiday, by eating coral reef fish that have fed on the algae that produces these toxins. Paralytic shellfish poisoning is also due to these same algae. The shellfish themselves appear to be immune to the brevetoxins. The toxin affects both nerve and muscle cells and results in some of the symptoms of tetany. Fortunately, fatalities are rare, as consumption usually only causes dizziness and tingling of fingers and toes.

Some rather well-known bacteria

Many bacterial names are now familiar to the general public after numerous press stories about a variety of infections such as MRSA, Clostridium, E. coli and Salmonella. Some of these bacteria produce toxins, which are of two types: endotoxins and exotoxins.

Arthur Warren Waite was a dentist in New York who succeeded in poisoning his mother-in-law by lacing her food with a mixture of the influenza virus and diphtheria germs. This unlucky lady died in January 1916. Dr Waite then decided to deal with his father-in-law, John Peck, by the same method, but with the addition of a nasal spray contaminated with tuberculosis germs. It took a couple of months, but eventually the father-in-law died. Following the old man’s death, forensic tests for arsenic were used and showed that Dr Waite had become somewhat impatient and so had added a little arsenic to speed things along. He was duly convicted of John Peck’s murder.

Endotoxins are attached to the inside of the bacterial cell wall and are only released when the bacteria dies and its tissues break down, releasing the cell contents into the surrounding tissues, with devastating effects. Typhoid fever is an example of an illness caused by an endotoxin, which is produced from the bacteria Salmonella typhi.

Other types of bacteria produce the far more common exotoxins. Exotoxins are released by the bacteria into the surrounding medium or tissue during the growth phase of bacterial infection. Many organisms that cause food poisoning produce enterotoxins, which are exotoxins acting specifically on the small intestine of the gut.

They usually cause massive fluid loss leading to copious diarrhoea. Staphylococcus aureus, Clostridium perfringens, Bacillus cereus, Vibrio cholerae, Salmonella enteriditis and Escherischia coli (E. coli) all cause food poisoning by producing these exotoxins. Clostridium perfringens can also cause gas gangrene by producing at least a dozen protein toxins, which wreak their havoc in a variety of ways.

Clostridium botulinum is yet another species that produces an exotoxin. This bacterium is spore-forming, and can be readily found in soil and mud. The botulinum toxin selectively affects the central nervous system and is the cause of Botulism. This extremely serious form of food poisoning requires intensive life support and treatment in hospital.

As well as the symptoms of vomiting and diarrhoea, the pupils become dilated, causing double vision or blurred vision. Difficulty in speech and swallowing, with shakiness and unsteady gait follow while bulbar palsy develops, resulting in a progressive flaccid muscle weakness and paralysis, which descends from the head and can result in respiratory paralysis and death from heart or lung failure within two or three days.

The botulinum bacterium thrives in improperly preserved foods, typically in canned raw meats. Honey has also been reported as a common source of infection, as it was found to contain Clostridium spores, which may be a particular danger to infants. The toxin, which is a protein, is destroyed by heating, so adequate sterilisation during the canning process will denature and thus destroy this toxin and others like it. This may be a powerful nerve poison that can be lethal, but, when used with great care and precision, it removes tics, spasms and, as a beauty treatment, wrinkles too.

Anthrax is an acute infection of farm animals, particularly sheep. In humans, it is caused by the germination of Bacillus anthracis, anthrax spores in the lungs or on the skin, both of which can be fatal. Pulmonary anthrax, the infection affecting the lungs, initially causes flu-like symptoms, followed quickly by severe respiratory problems, septic shock and death. Cutaneous anthrax affects the skin, causing the eruption of painless papules, rather like insect bites, which then develop into fluid-filled blisters that become dry and ulcerated, and then become covered by black scabs, or eschars. Fluid then accumulates throughout the body producing swelling from fluid retention – oedema – and death then follows.

Anthrax, which in the past was called Woolsorter’s disease, was well known to those in the weaving industries, as transmission to humans by contact with animal hair, hides or excrement was common in any trade involving wool or leather. Whether caused by working on cloth or on carpets, this is an example of an industrial disease. Even leather workers sometimes caught it. Such occupational hazards are no longer the problem they used to be, as today they are easily prevented or treated.

As well as these naturally occurring toxins, poisons have been born from synthetic substances, including many modern drugs. Some human creations meant to aid people have in fact created more problems. And even our own bodies can betray us, with excesses or deficiencies becoming poisonous. Read on for tales of man-made mischief and malfunctioning metabolism.