Last Updated February 20th, 2019
What Is Sleeping Sickness?
Sleeping sickness is an infectious illness caused by a parasitic protozoan known as Trypanosoma brucei. This protozoan enters the human body when a person receives a bite from an infected tsetse fly. This fly is only found in parts of tropical Africa, hence the disease is mainly limited to that region. This is why sleeping sickness is also known by the name ‘human African trypanosomiasis’. Till date, there are no known cases of transmission of the illness from one human to the other. Although it is possible to cure it, the disease can be extremely severe and life-threatening when treatment is not made available on time. In fact, as the illness escalates, the patient’s central nervous system is affected and they begin to display a range of neurological disturbances as well as personality changes.
What Is Responsible For Sleeping Sickness?
The pathogen responsible for causing this disease is a protozoan. In other words, it is a single-celled organism. This particular protozoan appears distinctively crescent-shaped under the microscope and bears hair-like structures called flagella to enable movement. This pathogen belongs to the species Trypanosoma brucei and there are more than one variant within this genus that are capable of causing this disease. The two subspecies most often implicated in cases of human infections are T. brucei gambiense and T. brucei rhodesiense.
In order to infect a host like a human or a cow, the pathogen requires a vector in the form of a tsetse fly. A vector is an intermediary that harbours the parasite and passes it on to other organisms but does not itself suffer from disease as it does so. The tsetse fly first acquires the parasite when it bites an infected animal or human and feeds on its blood. The protozoan remains within the intestines of the fly before eventually progressing into its salivary glands. This process takes a few weeks of time. It is only once the parasite has moved into the salivary glands that the fly becomes capable of spreading infection.
What Are The Symptoms?
When it feeds on human blood, the saliva of the infected fly introduces the protozoan into the human body where it then invades the lymphatic system. Here, the pathogen reproduces asexually and multiplies in number, eventually spreading to other parts of the body. Along with swelling of the lymph nodes, the patient experiences headaches, muscle aches, joint pain and fatigue. As the disease advances, it affects the nervous system and the patient may develop serious symptoms like seizures as a result.
The rate of progression of disease depends on the particular T. brucei subspecies involved. In some cases, it can take several years for the disease to develop and worsen. In other cases, the process can be much more rapid, on a scale of weeks or months. Usually, it starts off with a red mark and lesion at the site of the tsetse fly bite. This takes the form of a swollen nodule on the skin that is often painful. This occurs within a few weeks of receiving the bite. Soon, the patient the following symptoms:
- Red, painful nodule at the site of the bite.
- Enlargement of lymph nodes. These lumps will be tender and warm to the touch.
- Skin itching.
- Muscle aches.
- Joint pain.
- Weight loss.
What Are Some Complications To Watch Out For?
The symptoms listed above describe the first stage of disease. As we discussed in brief earlier, sleeping sickness typically proceeds in two stages of increasing severity. Unless treatment is made available at the initial stage, the disease can spread to the nervous system and cause a variety of neurological symptoms. Patients tend to spend longer periods of time asleep and may start to display signs of behavioural changes and mental confusion. In extreme cases, they may suffer from seizures or paralysis and even go into a coma. At this stage, death is a very likely outcome unless prompt and expert medical help is made available.
How Is This Disease Diagnosed?
In areas where access to medical care and laboratory facilities is available, there is usually no particular difficulty in diagnosing sleeping sickness. This disease is very common in equatorial Africa and doctors are always on the alert. The best way to identify the pathogen is by means of a blood test. The test seeks evidence of the parasite’s presence in the blood but if it proves inconclusive, it is advisable to take a sample of lymphatic tissue or lymphatic fluid and test that instead. T. brucei gambiense, for example, is trickier to diagnose through blood tests than T. brucei rhodesiense.
If the doctor suspects that the parasite has spread to the central nervous system, the patient will undergo a procedure known as the lumbar puncture. This is done so as to obtain a sample of cerebrospinal fluid for laboratory tests to check for the presence of the parasite.
What Is The Best Form Of Treatment?
Patients tend to respond well to medications. The earlier that treatment is commenced, the better the overall outlook. If the patient has already progressed to the second stage of disease, the specific drugs prescribed will vary as compared to patients in the initial stage.
At present, there is no definitive way to find out whether the patient has been completely cured. Certainly, the symptoms will abate. But the patient will be asked to come back for repeat tests to ensure that their blood and cerebrospinal fluid are clear of the parasite.
Most cases of sleeping sickness are limited to equatorial Africa, but with the rise of tourism and travel, it is quite possible for travelers to contract this illness. When they return to their home countries, they may carry the parasite with them but cannot pass it on to others. This is why the disease remains within a well defined geographical zone and has not escalated to the extent of a pandemic although it has certainly reached epidemic proportions within Africa.
If you are traveling to this zone, you should take adequate precautions to protect from bites. Or, if you have already suffered bites, stay on the guard for telltale symptoms and meet a doctor as soon as you can. Since not all tsetse flies are necessarily infected, and since the ones that are infected may not carry the parasite in their saliva as yet, there is a chance that the bite may be nothing worse than a simple bite. However, it is best to be cautious as the disease can be very serious.
- The trypanosome parasites are categorized into two groups based on their location – Trypanosoma brucei found in the sub-Sahara region of Africa (Tsetse fly) and Trypanosoma cruzi found in South America (kissing bug).
- Pets and domestic animals can also serve as a host to trypanosome parasites.
- The rural demography of sub-Saharan Africa is most vulnerable to this disease owing to the large breeding of the tsetse flies in this region.
- Effective screening methods have reduced the number of reported cases. In 2009, the number was first brought down below 10,000 and in 2015, it was as low as 2800.
- Around 97% of all the cases of sleeping sickness is caused by the parasite trypanosome brucei gambiense.
- The Republic of Congo records the highest number of cases of this disease; almost 70% of all the reported incidents in the last decade were from this country.
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Dos and Don'ts
- Accurate diagnosis of this disease is very important since the symptoms rendered by this disease often overlap with those of many other ailments. Hence, it is important to refer to the doctor immediately and seek proper medical attention.
- Dust and moving vehicles are favorite spots of the tsetse fly. Carefully check the interiors of a vehicle before boarding it to avoid insect bites.
- The tsetse fly remains largely inactive during the day and clusters in bushy regions. In spite of that, if disturbed they might bite you.
- Expose your skin too much. If one is in a region largely inhabited by the tsetse fly, it is important to wear clothing that fully covers the body. It should be of thick fabric since the fly can bite through the thin material.
- Wear Permethrin-containing clothing as an effective against the tsetse fly. Using insect repellent is a must.
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