The subtle-looking African tsetse fly feeds on the blood of vertebrate animals and its inflicted bite is more deadly than it appears. The tsetse African biting flies have a peculiar life cycle, can have its population reduced in various ways, transmit the wormlike trypanosomes, and are the cause of the sleeping sickness disease as discovered by Dr. David Bruce, parasitologist and early treatment provider.

Tsetse flies may be subtle in appearance as they are similar to house flies. Like all insects an adult tsetse fly has three sections: a head, thorax, and abdomen. The head is comprised of two huge eyes on each side and a large bulb on the bottom to which is attached a forward-pointing proboscis, or the part through which blood is sucked. Its large thorax is comprised of three combined segments, six legs, two wings, and two organs for balancing, called halteres. The abdomen is small but increases in size as the fly consumes enough blood to weigh twice as much as its original weight. Most tsetse flies are extremely tough externally. It is difficult to crush one.

Tsetse flies are different in four distinct bodily characteristics: proboscis, folded wings, hatchet cell, and branched arista hairs.

A long proboscis protrudes forward and is connected to the bottom of the pest’s head by an obvious bulb. The fly folds its two wings fully one above the other while resting. Hatchet cell refers to a cell in the center of both of a tsetse fly’s wings. These distinct cells are so called because of their hatchet shape. The bristle like parts of the creature’s antennae, called the arista, have branched hairs.

The tsetse fly has a peculiar life cycle. A female can only produce one egg at a time. The egg hatches inside the fly and the larva lives on a milky substance within the mother. The larva then leaves the mother and burrows into the ground. Once in the ground, the larva forms a hard outer case in which it changes. During this period the larva feeds on stored food. It is now a pupa. After twenty to thirty days, the case is broken and an adult tsetse fly emerges.

Sleeping sickness, transmitted by the tsetse fly, is a parasitic disease that is found in areas south of the Sahara Desert as far as the Cape of Good Hope. There are three strains of sleeping sickness, which affect man and beast. East African and West African are the two strains in humans while nagana is the form of the disease found in animals. Much African livestock suffer and three million cows die annually as a result of infections. However, many animals that dwell in Africa are able to resist the disease. One such breed of cattle is the N’dama breed.

Infected with either of the two strains an individual will not seem plagued for one or two weeks. The victim will subsequently experience recurring fever, pains, and aches. The back of the neck will swell eventually. This is a sign, called Winterbottom’s sign, which is used by doctors to determine the presence of the sickness. At a touch, the neck will pain. In the case of the East African strain, if it goes untreated there is swift death. The West African strain, however, will cause a longer period of illness, as long as two to three years. In this period, the victim will experience several symptoms that will cause suffering. These include intense headaches, lack of concentration and interest, weariness during daytime, and problems sleeping at night.

The tsetse fly is the transmitter of sleeping sickness, but the single-celled trypanosome is the actual culprit. These parasites are transparent and worm-like with a size twice that of a red blood cell. One end is pointed and the other has a hair-like structure called a flagellum, which it lashes in order to move. On each side of the parasite is a fin which it fans as it moves in the bloodstream. The parasite bears an interesting name, trypanosome, which means “auger body,” with respect to the twisting motion they make.

The species of trypanosomes that cause nagana and sleeping sickness have a complicated life cycle. They begin in an infected mammal and travel into the tsetse fly while it is having a blood meal. At this point of the life cycle, the trypanosomes are round cells referred to as amastigotes. Inside the stomach of the tsetse fly they begin to multiply in a process, which is called binary division and are not capable of infecting at this period. They remain in the stomach and grow. They then travel to the fly’s salivary glands. From the salivary glands of the fly, the trypanosomes travel to a mammal when the insect next bites. Now the mammal will be able to spread the parasites to the next fly that bites.

Once inside the bloodstream of a mammal, the immune system, or body’s defense against disease goes to work. The cells attack the foreigners by identifying their cell walls. Trypanosomes can change their cell walls so that the immune system cannot identify them. Eventually the body will recognize the change but by then the parasites will have altered their structure. This continual change tires the body.

Sir David Bruce was a British military surgeon and parasitologist who studied in the field of tropical disease and discovered that sleeping sickness was spread by the tsetse fly. To treat nagana, Dr. Bruce used a poisonous metal called arsenic. Later, other scientists used the drug Atoxyl, which comes from arsenic but was still quite unsafe as side effects included blindness. Today’s major treatment for premature sleeping sickness, however, is the drug suramin. Other drugs prescribed include: penlamidine or eflornithine for the West African strain, and eflornithine or melarsoprol for the East African strain. All these are considerably poisonous and taking the injections is a painful experience.

A method of preventing sleeping sickness is to destroy the dwelling places of tsetse flies. Burning trees that they live in may do this. Pesticides such as DDT served the purpose of killing the pests until DDT was deemed environmentally damaging. Today, the most effective method is to make male tsetse flies sterile. Scientists do this by exposing them to gamma radiation and due to the fact that females mate once in their lifetime, this method works. Traps are sometimes used to reduce fly populations and electrical ones will kill them instantly. Electrified blue cloth is used for a lure, as the flies are attracted to this color. Other traps channel flies into a compartment with pesticide-saturated walls. In order to attract the flies, carbon dioxide, the air we breathe out, is released near the trap. As tsetse flies find their prey by picking up this odor, they will be lured to the trap. A less expensive method is the use of animal urine instead of artificial gases.

The transmitters of the deadly sleeping sickness pandemic are the indistinct tsetse flies, African biting flies that transmit trypanosomes, whose populations are reduced in a range of ways. With war currently gripping some African nations, foreign aid is gradually becoming hard to obtain. Also, drug companies are behind in research pertaining to the disease and medicine production is slow. In spite of these drawbacks, hopefully affected countries will one day be rid of the tsetse fly menace.