Sleeping sickness is common in Africa because of the tsa tsa fly. What is the solution to this problem?
One of the most common diseases in sub-Saharan Africa and until the middle of the twentieth century also one of the deadliest is a disease known by its popular name "African trypanosomiasis" ("sleeping sickness" over an area that covers about ten million square kilometers, in about thirty-five countries with about sixty million inhabitants, About half a million people, women and children, are infected with the disease, of which about fifty thousand patients die every year, the damages caused to agriculture are estimated at about one billion dollars per year.
Since Europeans arrived in Africa - in the nineteenth century, there were three deadly outbreaks that caused millions of victims. In the first stage, the patient shows apathy and fatigue without signs of illness, so without an examination it is difficult to identify the disease
Clear signs of the disease begin with headaches, fever, joint pains, then acute anemia appears, damage to the nerves in the heart and kidneys, in the next stage the brain is damaged and the patient loses the ability to concentrate and coordinate, the sleep cycle is impaired - hence the name of the disease, without proper treatment the patient will enter a coma and die.
Two forms of the disease, one typical for eastern and southern Africa, and the other for the west and center, this is because of a different occurrence of two parasite formations in addition to many species that attack vertebrates Trypnosoma brucei gambiense in the west and center formation T. g. rhodesiense in the south and east of the parasite formation is a single-celled protozoa with an elongated elliptical shape, Protozoa Eukaryotes belongs to the class of eukaryotes. The parasite belongs to the Protistea kingdom, despite being single-celled it has the ability to self-move and is heterotrophic, meaning it feeds on organic compounds. These properties allow it to multiply in the blood system and then attack the lymphatic system and the nervous system. In South America there is a parasite of the same type that is spread by bedbugs and causes Chaga.
The parasite is spread by the tsetse-tsetse fly Glossina mortans, a member of the same family as houseflies, slightly smaller than it and more colorful. After fertilization, the fly larvae hatch in the female's stomach - the mother. Towards the incarnation stage, the female emits the pupae into moist sand and after a few days young flies bloom.
The fly feeds on the blood of mammals, mainly large herbivores and human beings. The fly - the female bites an infected animal or person and with the blood sucks the parasites, these multiply in the fly's salivary glands, undergo reincarnations and with the next bite the fly transfers the parasite to the next victim, the same parasites that are in the blood of the victim will form the next dose of blood for the fly that will bite and so the reincarnation cycle of the parasite
A fly flies
The flies are common in two different habitats, in southern and eastern Africa in savannahs and groves, in the west and center of the continent along rivers, streams and around water bodies.
Although the disease has been known in Africa since the fourteenth century, the direct cause of the disease was discovered only at the beginning of the twentieth century. The first medicines were based on arsenic and it turned out that more patients died from arsenic poisoning than from the disease, today there are effective medicines with which the disease can be cured, provided that it was detected in time. This is because the incubation period of the disease from the bite to the appearance of the first signs can be from three weeks to several months, so it is difficult to associate the external signs with the bite.
It is clear that the fly evolved together with large herbivores - especially the prime ones, and therefore many of the species have developed a partial level of resistance to the parasite. Thus, over the generations, the African cattle species - domesticated - also developed resistance, but the disease also affects them and is known as Nagana.
Beginning at the beginning of the twentieth century, white ranchers brought European cattle in order to praise the herds, the results were fatal, hundreds of thousands of sick and dead cows, in the meantime, mixed breeds with the African cattle were created and these were also vulnerable to the disease.
Until the Whites came to Africa, there were large areas where the Africans did not enter, and in the first place, knowing the risk and fearing their cattle, the settlement of the Whites changed the picture, due to lack of experience and in an attempt to take control of as many suitable areas as possible, the Whites entered areas where the fly was common, the result was fatal: fatal to cattle that were bitten and became ill, and in the next step Deadly for the natural environment, since after understanding the cause of the disease, the white settlers tried to eliminate the fly by spraying D.D.T. These sprays did harm the fly population, but along with the flies, many other animals were destroyed.
Another method in which the whites tried to fight the gnat was fencing, with the partially justified assumption that the carriers of the parasite are wild animals, huge areas were fenced off to prevent close contact between herds of domestic animals and wild animals. Here, too, the result was fatal for many species of animals: buffaloes, wildebeest, zebras, elephants, and many antelopes go on a periodic migration between different grazing and living areas, fences were placed without any consideration of the migration routes, animals that reached the fence walked along it back and forth until they died of hunger and thirst.
To this day, fences can be seen for hundreds of kilometers in DRAP, Botswana, Namibia, Zambia, Zimbabwe and more, but today, out of an understanding of the damage, they are trying to open "migration openings" in the fences that will allow the movement of wild animals.
Since there is no vaccine against the parasite - there is an effective treatment for human patients, and since the treatment of animals is not economically viable, the only option left is to destroy the carrier, i.e. the fly. Since the use of D.D.T. It is forbidden, and since spraying with other substances is neither desirable nor effective, traps are sprinkled in the fly's distribution areas: sticky surfaces that emit attractive odors, according to research it turned out that the flies are attracted to the urine odors of animals as well as to the dust that rises in the wake of large herds of animals, the flies are attracted to the smell and become infected. A new method - relatively more effective - is sterilization treatment by irradiation for males, since only the female bites and transmits parasites, the male does not eat and since each female only mates with one male - once, when the male is sterile, there will be no continuation of the generation.
By radioactive irradiation, many males are sterilized and freed to fulfill their damaged role, and thus there are fewer and fewer flies in a treated area. The method is called: the SIT Sterile Insect Technique.
Zanzibar is an island off the coast of Tanzania, the island was home to the disease that hit the villagers and their livestock the most, since it was a relatively isolated island it was easy to turn into an experimental laboratory using the above method, in the laboratory in Tanga in Tanzania about a million females were bred from which they received about seventy thousand infertile males a week, about eight million infertile males They were released into the territory, and the success was one hundred percent. Today, four years after the beginning of the distribution of the sterile males, the health authorities on the island claim that Zanzibar is free of tsa-tsa flies.
This success represents a chance for an effective solution in other parts of the African continent where traps are used and sometimes insecticides are sprayed. As someone who cares about the natural environment and who cares about it, along with many other environmentalists, I also see the positive side of the presence of the fly: until not long ago, there were areas where the fly population was known to be protected from the negative effects of human presence, that is, such areas remained without human harm . It is hoped that with the thinning of the fly populations in such areas and as a result a higher human presence, the people will learn and know how not to harm the natural environment.
