Sleeping sickness: symptoms, causes and treatment.

Summary of the characteristics of sleeping sickness, caused by tsetse fly bites.

Sleeping sickness or African trypanosomiasis is a parasitic pathology dependent on a vector dependent on a vector for its transmission, in this case, a fly.

It is a disease that has generated several epidemics during the 19th and 20th centuries in various parts of Africa. Even so, today its distribution is focal, so it is endemic in 36 African countries. Like most diseases dependent on invertebrate vectors of transmission, this pathology flourishes mainly in warm environments with poor health conditions.

As distant as it may seem to us, knowing the facts about this disease is essential, both as a matter of wisdom and human empathy. Therefore, here we will look at various facts about sleeping sickness.

Sleeping sickness and the fly, two inseparable concepts.

Before going fully into the clinical picture and the causative agent of this pathology, it is necessary to talk about its effect on vulnerable populations. The World Health Organization (WHO) provides us with various statistical data to be taken into account. These are the following:

• African trypanosomiasis is endemic in 36 countries in sub-Saharan Africa.
• The inhabitants of rural areas are the demographic sector most vulnerable to this disease.
• In 1998, there were an estimated 500,000 cases, most of them untreated.
• Due to control efforts promoted by Western countries, this figure has fallen to a total of 1,446 cases in 2017.
• In the last 10 years, more than 70 % of the cases have occurred in the Democratic Republic of Congo.
• This is the only region in the world where more than 1,000 cases a year are still being diagnosed today.

As we can see, sustained control initiatives have had a very positive effect on the distribution and spread of sleeping sickness. Still, until the number of infected people is reduced to 0, we cannot claim that this pathology is fully under control..

Getting to know the parasite: Trypanosoma brucei

Unlike other pathologies of parasitic origin, African trypanosomiasis is not caused by a single microorganism. In this case we are dealing with two hemoflagellate protozoa of the genus trypanosoma. These are the species Trypanosoma brucei gambiense y Trypanosoma brucei rhodesiense.

The first is the most epidemiologically important, as it is estimated to be the cause of more than 98% of reported cases. The second species only occasionally uses humans as hosts, as it has specialized in infecting cattle and other domestic animals.

These small, worm-like, semitransparent protozoa have a vertigo-like life cycle.. This is a summary of this process:

• The tsetse fly injects one of the parasite forms, trypomastigotes, into the Blood of the host (which may be human).
• Thanks to the bloodstream, the parasites reach other organs and fluids (such as the lymphoid), and multiply there by binary fission.
• These blood trypomastigotes are ingested by the fly when it bites an infected person.

The trypanosome parasite undergoes several changes within the fly itselfHowever, knowing that these protozoa multiply in various organs and are transported through the host's bloodstream is enough to understand the situation of sleeping sickness at the clinical level.

We emphasize that we are going to delve into the symptoms and treatments of the pathology generated by the parasite t. b. gambienseparasite, since it is the species that most affects human beings.

Symptoms of African trypanosomiasis.

According to various bibliographic sources, this pathology has three different phases.

1. Initial phase

At the site of the tsetse fly bite, a local inflammatory process occurs a local inflammatory processwhich gives rise to a structure called trypanoma or chancre. This is a painful cutaneous ulcer, characterized by a white halo on its extraradius. Trypanoma ends with the appearance of a scar two to three weeks after the bite.

Hemolytic phase

After an incubation that can last from a few days to several years (with an average of 1-3 weeks), the patient begins to manifest clinical signs that respond to the dissemination and reproduction of the parasite through the lymphatic-blood system..

This involves the appearance of very high intermittent fevers, arthralgias (joint pain), adenopathies (hard, painless and mobile lymph nodes), tachycardia, anemia, weight loss and itching, among others. As we can see, this is not a pleasant clinical picture at all, but the worst is yet to come.

3. Neurological phase

This begins when the parasite crosses the blood-brain barrier, i.e., a selectivethat is to say, a selective layer that isolates the central nervous system of the human being. As you can imagine, the presence of a flagellated protozoan in the nervous system causes symptoms that are both striking and worrisome.

From this point on, we move more into a clinical picture based on a clinical picture based on behavioral changes. The patient shows sensory problems (hyperesthesia, increased sensitivity to touch), psychic abnormalities (mood swings, irritability, emotional fluctuation), sleep disorders and various motor and endocrine problems.

This change in the circadian clock of the infected person, which causes insomnia, can causewhich causes chronic insomnia in the patient, gives the name of sleeping sickness to this pathology.

In addition to having entered the central nervous system, some of the parasites still remain in the individual's bloodstream, causing the symptoms of the hemolytic phase to show during the neurological stage as well. In the absence of treatment, this period leads to a profound alteration of the organism (cachexia), coma and death.

Treatment

Any person diagnosed with African trypanosomiasis should be treated according to the should be treated according to the parasite species causing it and the stage of the disease.. Naturally, a person who presents with these protozoa only in the blood and another in whom they have invaded the central nervous system will require different clinical approaches.

For example, according to the Centers for Disease Control and Prevention (CDC), pentamidine is an antiprotozoal that acts by inhibiting the parasite's synthesis of proteins and nucleic acidswhich limits and inhibits its growth. This drug is administered mainly to patients who are still in the hemolytic phase of the T. b. gambiense parasite. Suramin has the same function, but in this case, it acts against T. b. rhodesiense.

The neurological phase, due to its more delicate nature, requires more aggressive medications.. In these cases melarsoprol is usually administered, an arsenic derivative that can cause side effects sometimes almost worse than the disease (such as reactive encephalopathy leading to death of the patient in up to 10% of cases).

There are other possible treatments, but in summary, it can be said that this pathology requires a very specific clinical approach, to be carried out by specially qualified personnel.

Conclusions

It is not common to find a pathology of parasitic origin that affects so many levels of the patient's health. As we have seen, sleeping sickness causes symptoms ranging from fevers to mood swings, lack of sleep and hypersensitivity to touch.

Of course, it is surprising to observe how the presence of a parasite in the bloodstream and the central nervous system (CNS) is able to modify the patient's routine and lifestyle. is capable of modifying the patient's routine and lifestyle to such an extent that he or she can no longer be considered a functioning human being.to such an extent that he or she can no longer be considered a functioning human being.

It is usual that, from a Westernized point of view, this type of pathology is alien and uninteresting to us. Beyond the possible concerns that may be generated by a sporadic trip to the African continent as tourists, diseases such as this one require understanding and comprehension for a mere question of empathy.

These pathologies cannot be addressed by the deficient monetary conditions of the countries in which they originate, and therefore, the action of bodies such as the WHO has become more than necessary to decrease their prevalence.

Bibliographic references:

• de la Salud, A. M. (1983). Human African trypanosomiasis (No. WHA36. 31). World Health Organization.
• Sleeping sickness, World Health Organization (WHO). Retrieved August 7 from https://www.who.int/es/news-room/fact-sheets/detail/trypanosomiasis-human-african-(sleeping-sickness).
• Franco, J. R., Ruiz, J. A., & Simarro, P. African trypanosomiasis.
• Gomez, V. Trypanosoma brucei: characteristics, morphology, life cycle.
• Sleeping Sickness, CDC. Retrieved August 7 from https://www.cdc.gov/parasites/sleepingsickness/biology.html.
• Torres, O. M., & Cá, G. (2003). African trypanosomiasis. Case report. MediCiego, 5(1).