The Most Dangerous Insect in the World
If asked to name the deadliest insect in the world, most people would search their minds for some sinister-looking spiders or scorpions, or exotic garden pests. However, if we define ‘deadly’ in terms of the number of people who die directly as a result of the insect, one of them leads the field, by far: the mosquito. As a blood-sucking pest, it transmits diseases to over 700 million people a year, killing a fair proportion of them in the process. No other insect comes even close to this.
Although all mosquitoes are nectar feeders, the females also need protein from a blood meal in order to produce eggs. To find this, they have a keen sense of smell, detecting the sweat and other organic compounds of mammals, such as the carbon dioxide they exhale. Scientific tests have proven that some people attract more mosquitoes than others, presumably having a better ‘scent profile’ — in fact, so adept are female mosquitoes at following these trails, they can infiltrate buildings through pipeways and air-conditioning ducts as they move inexorably towards their victims. Upon biting, they inject an anti-coagulating saliva into the flesh, and it is this fluid (and not their blood) which may contain the range of viral and parasitical nasties for which mosquitoes are notorious.
Yet even without such diseases, mosquitoes are an irritating nuisance which can occasionally cause serious injury. Upon being bitten, the body’s immune system is activated, and subsequent bites trigger antibodies which cause inflammation and itching, particularly with young children. More bites can increase such sensitivity, resulting in pronounced swelling and blistering — wounds which can occasionally become infected, particularly when scratched. Two famous victims of infected mosquito bites are Lord Carnarvon, the Egyptologist who played a role in the discovery of Tutankhamen’s tomb, and the British poet, Rupert Brooke, passing away in Egypt and Greece, respectively.
But the real danger will always be mosquito-borne diseases. Dengue fever, West Nile virus, and several encephalitis-type diseases are all modern day killers. A less deadly but more insidious example is filariasis, a disease named from the thread-like parasites which migrate to the body’s lymphatic system, causing parts of the body to permanently swell to grotesque proportions. Yet, as distressing as all this is, in terms of its death toll, the worst disease is undoubtedly malaria. Carried by the Anopheles mosquito, this parasite causes fever, shivering, joint pains, vomiting, and, if left untreated, a painful death. It infects over two million people a year, most of them children, killing over one quarter in the process.
The Aedes Aepypti mosquito is the species responsible for that other great killer: yellow fever. This is a viral disease, but limited to tropical areas, primarily in Africa, but also Central and South America. After high lever, nausea, and joint pains, the virus attacks the liver, causing the host’s skin to turn yellow (hence the name), with death following some days later. Its toll is much smaller than malaria, with about 200,000 infections and 30,000 deaths every year, mostly in Africa. Unlike malaria, there exists a vaccine, and extensive vaccination programs sponsored by the WHO have had some success, whilst travelers to disease-prone areas are usually similarly protected.
With such a death toll, it took a surprisingly long time before the link between mosquitoes and disease was realised. This is exemplified in the construction of the Panama Canal — that ambitious project to excavate a passageway for ships through that narrow Central-American nation. In the 1880s, the French struggled for eight years in insect-infested jungle, but the death toll from malaria and yellow fever made it very difficult to maintain an experienced work force. After the loss of 22,000 lives, work was abandoned, yet shortly afterwards, a British doctor in India, Ronald
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