31 October 2018
The Bite That Kills
How can a bite so small and quick be so dangerous? The answer lies with the fly Tsetse. This specific fly has shown how dangerous it can be without trying, it is simply doing what it needs to survive just as humans and other animals do every single day. They have an instinct to feed when hungry, yet once they feed they have just sentenced their meal to a slow, painful, and fatal death. The Tsetse Fly may seem average to the human eye but happens to be very dangerous, and here’s why, they’re dangerously venomous, as well as the advantage they have of appearance and size. They’re undetected killers but once acknowledged it’s too late.
The Tsetse Fly isn’t born with the sleeping disease it’s contracted by feeding on infected animals carrying a parasite called Trypanosoma. After contracting the parasite, the Tsetse Fly becomes the dangerous carrier of disease and sickness, leading to the death of “over 75,000 people” (Conca) and taking the lives of “more than 3 million livestock in sub-Saharan Africa” (Conca). A bite from the Tsetse Fly is quite painful and venomous. The venom is within the parasite that creates a vector-borne disease. Which means the Trypanosoma transmits an infection into humans and animals. This then triggers the sleeping disease in humans and Nagana in animals. The disease is hard to catch early because the host will experience headaches, fever or rashes, and may think it’s a common cold or allergic reaction but then unexpectedly the parasite will damage “the central nervous system which causes disorientation, personality changes, slurred speech, seizures, difficulty walking and talking, and finally death” (Conca).
The Tsetse Fly survives only on blood nothing else, which means feeding is something it will always do. Once the Tsetse Fly feeds, the disease is spread and the parasite begins to reproduce nonstop inside its host. The Tsetse Fly has “several salivary molecules that are essential for sucking up and digesting blood” (Morin).” The salivary molecules produce by the Tsetse Fly helps “to reduce blood coagulation and vessel constriction, as well as inflammation and irritation” (Morin). Unfortunately, if the Tsetse Fly is infected then these molecules are reduced, requiring longer feeding times and increasing the likelihood that parasites will be spread to a new host” (Morin). The reason this disease is so dangerous is that it can enter your brain.
There is no cure or vaccine for the sleeping disease, but there are medications that help depending on what stage of sickness you are in. “The first stage is the bite from the tsetse fly, after which the parasite infects the person’s blood. In the second stage, which was not previously identified, it appears in the cerebrospinal fluid and in three membranes that surround the brain, known as the meninges. In the third stage, the brain’s protective borders break down and a “mass invasion” of trypanosomes crosses the blood-brain barrier and attacks the brain” (Hogenboom). Without treatment, the disease is very dangerous and ultimately fatal once it has reached your brain.
Tsetse Flies mainly reside in Africa, where they enjoy woodlands and if they make the effort to fly a short distance then grasslands as well. “In general, tsetse fly activity declines soon after sunset. In woodland? environments?, male tsetse flies are responsible for the majority of attacks on humans; the females usually feed on larger animals” (Britannica). Since the Tsetse Fly has the advantage of appearance, it is not feared as much as it should be. The Tsetse Fly looks very similar to the housefly; this may be because they both are from the Muscidae family. House Flies aren’t known to be dangerous, they are annoying and persistent, but never dangerous. This means the Tsetse Fly has an undeniable advantage of not just appearance but size as well.
A glance at the Tsetse Fly to the human eye it’s just an annoying fly, but once it lands and takes a bite, you see how dangerous that little fly becomes. “Tsetse flies are robust, sparsely bristled insects that usually range from 6 to 16 mm (0.2 to 0.6 inch) in length. Tsetse flies are rather drab in appearance: their colour varies from yellowish brown to dark brown, and they have a gray thorax that often has dark markings” (Britannica). There are ways to distinguish the Tsetse Fly and hopefully fast enough to prevent getting bitten. “All tsetse fly species have a long probe, or proboscis, extending horizontally from the base of their head. When resting, their wings fold over the abdomen, one exactly on top of the other” (Macdonald).
It is very clear how dangerous the Tsetse Fly species can be and what damage it has done to thousands of humans and millions of livestock. However, the Tsetse Fly attacks do not occur as often as it may seem. “Male tsetse fly adults may live two to three weeks, while females can live for one to four months” (Britannica). The lifespan of the Tsetse Fly is not very long-lived; they survive for a minimal amount of time. Another setback for Tsetse Flies would be how they reproduce. “Insects are generally negligent parents: a female lays dozen or hundreds of eggs and flies off, leaving the young to fend for themselves. Most will die but a few will survive to lay hundreds more eggs” (Zhang), but a female Tsetse Fly like humans keeps her eggs and larva in the safest place possible for the longest time: inside her uterus” (Zhang). This means that a female Tsetse can only carry one larva at a time not multiple. “When adequately fed, a female tsetse fly will produce one larva about every 9 or 10 days throughout her life. Without a sufficient blood meal, however, the female fly will produce a small, underdeveloped, and nonviable larva” (Britannica). The less likely they are to reproduce then the less likely they are to repopulate. There are even conventional methods that are being put in place to ensure the population of Tsetse Flies declines. One conventional method includes releasing sterile males into a wild population. “The sterile males’ unions with females produce no offspring, and, since female tsetse flies’ mate only a single time in life, those that mate with sterile males are themselves rendered sterile for all practical purposes. The method has been found to totally eradicate tsetse flies in localities where their populations have already been significantly reduced by conventional methods” (Britannica).
After researching and analyzing the Tsetse Fly, it is clear that they are very dangerous insects. The danger lies within the disease they spread, and their advantage of appearance and size. Tsetse Flies are not born killers or disease carries but are used and seen as so. Unfortunately, they will continue this path of destruction, because it seems so natural and instinctual to them.
Britannica, The Editors of Encyclopaedia. “Tsetse Fly.” Encyclopaedia Britannica,
Encyclopaedia Britannica, Inc., 16 Nov 2017,
https://www.britannica.com/animal/tsetse-flyConca, James. “Irradiating And Eradicating The Tsetse Fly Scourge.” Forbes, 2 Apr 2015,
https://www.forbes.com/sites/jamesconca/2015/04/02/irradiating-and-eradicating-the tsetse-fly-scourge/#184f5cb55c04Hogenboom, Melissa. “A bite from this fly puts you into a deadly sleep.” ?BBC, 19 Dec 2016,
www.bbc.com/earth/story/20161216-a-bite-from-this-fly-puts-you-into-a-deadly-sleepMacdonald, Jessica. “The Tsetse Fly and African Sleeping Sickness.” ?Tripsavvy, 10 July 2017,
www.tripsavvy.com/avoiding-the-tsetse-fly-on-safari-1454081Morin, Monte. “Blunting the tsetse fly’s deadly bite.” ?Los Angeles Times, 24 Apr 2014,
http://www.latimes.com/science/sciencenow/la-sci-sn-how-the-tsetse-flys-savage-bite causes-sleeping-sickness-20140423-story.htmlZhang, Sarah. “Tsetse Flies Lactate and Give Birth to Live Larvae.” ?Discover Blog, 20 Apr,