Tsetse Fly

Tsetse fly, as the name suggests is of the class Insecta and the name can also be spelt as tsetse and is popularly called a tik-tik fly, any of roughly two to three dozen species of blood-sucking flies in the Muscidae that exclusively exist in Africa and transmit sleeping sickness by the African trypanosomiasis in humans and nagana in domestic animals. The tsetse fly is a member of the housefly family of insects. 

Tsetse flies are present in mid-continental Africa in 23 different species. Tsetse flies can be found in open woods. They have existed on the earth in the same form for at least 34 million years. Tsetse flies transmit parasites and due to this, it is seen that the tsetse fly causes diseases in humans and animals that are lethal. Tsetse flies are distinguishable from other flies by a forward-projecting piercing proboscis on the head that can pierce the skin. Humans, domestic animals, and wild game blood are all easily available to them. 

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All About Tsetse Fly

• Physical Appearance and Anatomy of Tsetse Fly - Tsetse flies can grow to be 0.2 to 0.6 inches long. Tsetse flies have dark markings on the thorax and chest and are yellowish-brown or dark brown in hue. Tsetse flies resemble giant house flies. It has thin, bristle-like hairs covering its body. Tsetse flies, unlike house flies, fold their wings entirely when resting, with one wing tucked beneath the other. The head, thorax, and abdomen make up the body of the tsetse fly. Tsetse flies have a huge head, three pairs of legs, and two pairs of wings. It also has a pair of halteres, which are modified wings that help it maintain balance while flying. 

• Biology of Tsetse Fly - Tsetse flies are diurnal animals, meaning they are active during the hottest portion of the day. Tsetse flies are parasitic flies that feed on the blood of various animals. The proboscis, or mouth equipment, is fashioned like a blade. It's used to pierce the skin and make blood-sucking easier. Two species of tsetse fly can transmit parasites that cause sleeping sickness in humans and nagana, an illness that is comparable to sleeping sickness in domestic animals.

• Life Cycle - Female tsetse flies like huge animals, while male tsetse flies prefer humans. Female tsetse flies only mate once in their lives, although they can generate young every ten days. One by one, the eggs hatch inside the female's body. The fully developed larva resembles a maggot and develops outside the female's body. Larva crawls into the dirt and builds a hard, protective shell around itself. The pupa is the name for this stage of development. The mature bug emerges from the cocoon a few weeks later.

• Diet and Nutrition - Larvae eat milky fluid generated by the uterine wall, which is rich in nutrients. The larva develops swiftly when the mother consumes big amounts of blood. When nourishment is scarce, larvae become tiny, underdeveloped, and unviable. Normally, insect larvae feed themselves before pupation, but tsetse development occurs without feeding until it emerges as a full adult. The development is solely dependent on the nutritional resources provided by the female parent, demonstrating the importance of blood as a source of sustenance. The female must obtain sufficient energy to meet her own demands, as well as the needs of her developing child, as well as to store the nutrients that her offspring will require until it matures into an adult.

Sleeping Sickness Fly - Life Cycle and Treatment 

African Tsetse fly causes this disease that is called African trypanosomiasis, generally known as sleeping sickness, which is divided into two forms, each named after the African location where it was first discovered. The parasite Trypanosoma brucei rhodesiense causes East African trypanosomiasis. The parasite Trypanosoma brucei gambiense causes West African trypanosomiasis. These types of tsetse fly are only found in rural Africa, transmitting both kinds of African trypanosomiasis. If bitten by a tsetse insect fly carrying the Trypanosoma brucei rhodesiense or Trypanosoma brucei gambiense parasite, a person will have East or West African trypanosomiasis. The percentage of tsetse flies infected with these parasites is quite low. Tsetse flies of this type are exclusively found in rural Africa. An infected pregnant mother can convey T. brucei gambiense infection to her baby on rare occasions. Other methods of infection, including sexual transmission, blood transfusion, and organ transplantation, are feasible but rare and little established.

Life Cycle in a Host

An infected tsetse fly (genus Glossina) injects metacyclic trypomastigotes into skin tissue during a blood meal on the mammalian host. The parasites make their way into the bloodstream via the lymphatic system. They change into bloodstream trypomastigotes inside the host, which are transferred to different parts of the body, reach other body fluids, and continue replicating via binary fission. Extracellular phases reflect the whole life cycle of African trypanosomes. When a tsetse fly feeds on the blood of an infected mammalian host, it becomes infected with bloodstream trypomastigotes. In the fly’s midgut, the parasites transform into procyclic trypomastigotes, multiply by binary fission, leave the midgut, and transform into epimastigotes. The epimastigotes reach the fly’s salivary glands and continue multiplication by binary fission. The cycle in the fly takes approximately 3 weeks. Rarely, if the mother is infected during pregnancy, gambiense can be passed down to the children.

Clinical Symptoms 

Headaches, irregular fevers, swollen tissues, and joint problems are among the initial symptoms and indicators of sleeping sickness. Later on, the parasites infiltrate the brain, resulting in mental problems, coma, and death. In gambiense sleeping sickness, there is typically a latent phase before any noticeable symptoms or indications arise, which can persist for months or years. In rhodesiense sleeping sickness, this latent phase does not exist or is very short. Infections with the gambiensis virus normally progress slowly, whereas infections with the rhodesiense virus are usually severe. Both gambiense and rhodesiense diseases are lethal if left untreated. 

Treatment

Anyone diagnosed with African Trypanosomiasis should be treated with a specific drug and treatment course based on the type of infection and disease stage concerning the involvement of the central nervous system or absence of it. In the United States, pentamidine, the recommended treatment for first-stage T. b. gambiense infection, is accessible. The other medications used to treat African trypanosomiasis, suramin, melarsoprol, eflornithine, and nifurtimox, are not commercially available in the United States but can be obtained via the Centers for Disease Control and Prevention (CDC). In 1994, eflornithine, a new drug, was successfully used to treat all stages of gambiense sleeping sickness. However, the drug's manufacture halted by the end of 1995. For African trypanosomiasis, there is no curative test. Patients should be regularly observed for 24 months after treatment to ensure that they do not relapse. In order to determine the presence of trypanosomes in bodily fluids, including CSF, if symptoms recur, an examination of body fluids, including CSF (cerebrospinal fluid), will be required. Physicians can speak with CDC staff to obtain these therapy medications that are otherwise unavailable.

Prevention and Control of Sleeping Sickness Fly

• To prevent East African trypanosomiasis, there is neither vaccination nor a suggested drug.

• Wear long-sleeved shirts and slacks, as well as other protective clothes. Tsetse flies can bite through thin fabrics, therefore medium-weight clothing is recommended.

• Dress in a neutral colour scheme. Tsetse flies are drawn to both bright and dark colours.

• Before entering, inspect vehicles for tsetse flies. The flies are drawn to moving objects.

• Bushes should be avoided. During the hottest part of the day, the tsetse fly is less active. It hides in the bushes but bites if disturbed.

• Pesticides, sterilisation of male flies, and clearing and burning of the woodlands where they lay eggs are all used to combat these insects.

• Insect repellent should be used. Though insect repellants have not been demonstrated to prevent tsetse fly bites, they have been shown to protect other insects from biting and causing harm.

• Large blue cloths can be used as a lure to attract tsetse flies. Another effective way is to release sterile irradiated male flies. Because females only mate once in their lives, the population is drastically reduced.

Interesting and Fun Facts About Tsetse Fly

1. The sleeping illness is characterised by swollen lymph nodes, headaches, fever, and bodily emaciation. Every year, this disease kills between 250.000 and 300.000 people.

2. Tsetse flies reproduce four times a year, for a total of 31 generations in a lifetime.

3. Tsetse fly larvae produce a poison capable of killing humans.

4. Tsetse flies can live for one to three months as adults.

5. People and their animals simply did not reside in tsetse-infested areas prior to the twentieth century. Using pesticides after World War II generated as many issues as it alleviated in the twentieth century.