Sleeping Sickness – African Trypanosomiasis

Sleeping sickness, or African Trypanosomiasis, is a disease caused by a parasite. Left untreated, those infected will die in almost 100% of cases. There have been a number of recorded outbreaks in the last two centuries; however, sustained efforts to control instances of African Trypanosomiasis have reduced new cases by 97% in the last 20 years.

What is African Trypanosomiasis?

African Trypanosomiasis, also known as sleeping sickness, is a disease that is caused by a microscopic parasite. The parasite, called Trypanosoma brucei, is spread via the bite of the tsetse fly (Glossina species).

People are most at risk of developing African Trypanosomiasis in sub-Saharan Africa as this is where the tsetse fly is usually found.

Both humans and animals can be affected by this disease. In humans, symptoms often begin similar to that of a mild fever, but if left untreated African Trypanosomiasis causes complications and ultimately death.

The symptoms of the disease can include a sleep disorder. This manifests as an inversion of the usual wake/sleep cycle, where a patient is exhausted and sleeps all day and suffers from insomnia at night. It is also characterised by patients getting a sudden, uncontrollable urge to sleep; thus, it is also known by the name African Sleeping Sickness.

What causes African Trypanosomiasis?

African Trypanosomiasis is spread by the tsetse fly. These flies bite during the day and both male and female flies can contain the parasite responsible for African Trypanosomiasis. Tsetse flies live in rural areas and are usually found in woodlands, thickets or in trees and vegetation along streams. Only a small proportion of the tsetse fly are infected with this parasite.

There are two subspecies of this parasite: T brucei gambiense, which is responsible for most cases in West and Central Africa, and T brucei rhodesiense, which is found in East Africa.

When the tsetse fly bites through the skin, it injects a parasite from the species Trypanosoma brucei, into the bloodstream. These microscopic parasites are capable of quickly dividing and spreading throughout the body. They will rapidly begin to infect the:

Bloodstream
Lymphatics
Nervous system

It is important that a person who is infected with African Trypanosomiasis receives fast and effective treatment in order to make a full recovery.

Although almost all cases of African Trypanosomiasis are caused by the tsetse fly, there are some documented cases of the disease being spread in other ways. These include:

Mother to child – the disease may be passed via the placenta during pregnancy
Accidental infection – this can happen in lab settings when someone accidentally comes into contact with a contaminated sharp
Insects – there is a very small chance that other blood-sucking insects may be able to spread African Trypanosomiasis
Sexual contact – there is limited scientific evidence to support this claim, although various disease centres and the WHO acknowledge it as a possibility

The vast majority of cases happen in rural areas. The people most likely to be exposed to infected tsetse flies include those who depend on farmwork or other agriculture such as:

Fishing
Animal husbandry
Hunting

It is difficult to eliminate the chance of being bitten by a tsetse fly, although some steps to minimise the chance of a bite include:

Wearing neutral colours. Tsetse flies are said to be attracted to bright and dark colours, therefore wearing neutral coloured clothing may be less likely to catch their attention.
Tsetse flies can bite through thin fabric, so wearing better quality clothing may offer some protection from bites.
Check vehicles for flies before getting inside as tsetse flies are said to be attracted to moving cars.
Avoiding bushes. Tsetse flies will rest in bushes during the day when temperatures are at their hottest.

Unlike many biting insects, tsetse flies are not affected by insect repellent, although using a good quality insect spray can deter other biting insects that also cause disease.

Signs of African Trypanosomiasis

In the very early stages of infection, a patient may notice swelling or itching at the site of the bite or bites.

As the disease begins to take hold, symptoms will begin to develop. This is sometimes known as stage one of the infection. Stage one symptoms include:

Fever
Muscle aches
Joint pain
Headaches
Fatigue
Tiredness/exhaustion
Reverse of the usual wake/sleep cycle
Rashes or skin lesions
Enlarged lymph nodes

If the disease progresses to stage two, additional and more serious symptoms will develop. These may include:

Heart problems (arrhythmia)
Ataxia
Disordered thinking
Altered mental state
Seizures
Coma

In the later stages, the major organs of the body can be affected, including the heart, brain and liver.

The symptoms of stages one and two of the disease intersect, which can lead to delays in treatment whilst healthcare workers assess which stage a patient is at.

How quickly the onset and progression of symptoms happens will usually depend on the type of African Trypanosomiasis the patient has.

Types of African Trypanosomiasis

There are two different types of African Trypanosomiasis that are spread by two different tsetse subspecies. As they are spread by different subspecies, the two diseases do not overlap, except in Uganda where both variants have been found in the past.

Trypanosoma brucei gambiense – this is the most prevalent form that is found in 24 countries in Western and Central Africa. It accounts for 92% of all cases. Symptoms may take some time to show up, with the disease progressing to stage two usually within 300-500 days.
Trypanosoma brucei rhodesiense – this type of African Trypanosomiasis accounts for 8% of all cases and is found in 13 countries in Eastern and Southern Africa. It is sometimes referred to as East African Sleeping Sickness. The onset of symptoms usually occurs soon after infection with the disease progressing quickly. Infection usually progresses to stage two within an estimated 21-60 days.

African Trypanosomiasis is not only a problem for humans. It can also affect domestic and wild animals, most commonly cattle. When the disease affects animals, it is called Animal African Trypanosomiasis (AAT). The disease is responsible for an estimated 3 million cattle deaths per year.

Animals infected with AAT become weak, lethargic and anaemic. AAT also reduces milk production levels in cattle. Working in farming is a significant risk factor for being exposed to the disease. Infected cattle in particular are known to be linked to outbreaks of African Trypanosomiasis in villages and communities.

In addition to the health risks posed to humans from infected animals, there are also financial implications when livestock (including pigs, goats and cattle) contract the disease. Many people in sub-Saharan Africa rely on their cattle herds to make money. If left untreated, animals will usually die which can have a devastating economic impact on farming communities.

The impact of African Trypanosomiasis

African Trypanosomiasis posed a significant threat to public health in the past. Currently, however, the disease seems to be under control with only 600 cases of West African Trypanosomiasis reported to the World Health Organization in 2020.

The vast majority of people infected are native to the areas where the tsetse fly lives; however, some foreign travellers have also been known to get infected, most commonly whilst on safari.

People from rural areas of Africa, often farm and field workers, are disproportionately affected by African Trypanosomiasis and these people may also be facing additional challenges and barriers to treatment, such as:

Poverty
Lack of education
Lack of access to infrastructure
Limited access to healthcare
Malnutrition
Conflict
Political instability

Being sick when you have no access to government funds and you rely on being able to do physical work to support yourself and your family, will put significant strain on people and communities.

Epidemics of African Trypanosomiasis are usually localised, meaning an entire community or village is affected at once. This can have a widespread social and economic impact on people. When an area is known to be at risk, it is possible to screen people for Trypanosoma brucei gambiense to assess who has been exposed to the parasite. If screening can be implemented, it can lead to faster and more effective treatment and more positive outcomes for the exposed population.

Treatment for African Trypanosomiasis

There is currently no vaccine for African Trypanosomiasis. Anyone who is suspected of having the disease should make contact with a doctor immediately, preferably one who has expertise in infectious diseases.

Early intervention is key in the treatment of African Trypanosomiasis.
If a patient is treated in the early stages of their symptoms (stage one) the outlook for a full recovery is good.
If the disease has spread and the patient is in stage two of symptoms, it means that the parasite has already entered the central nervous system (CNS).
Patients in stage two of African Trypanosomiasis may have neurological and behavioural symptoms.

Diagnosing the disease can be difficult. A diagnosis is usually made by checking samples of blood, bone marrow or body fluid, such as a sample of lymph node aspirate, for the presence of the parasite.

The most reliable way to assess what stage the patient’s symptoms are at is by examining a sample of their cerebrospinal fluid (CSF).

Patients are treated for African Trypanosomiasis with a course of drugs, depending on the type of infection and what stage it is at. In 2019, new treatment guidelines outlined the use of six different drugs to treat African Trypanosomiasis.

Treatments used in stage one infections of gambiense African Trypanosomiasis:

Pentamidine – given as an intramuscular injection.
Eflornithine – given intravenously. Usually administered alongside nifurtimox-eflornithine combination therapy (NECT) although can be used alone.
Fexinidazole – given orally. Should only be given to patients who have had an adequate food/water intake.

Treatment used in stage two infections of gambiense African Trypanosomiasis:

Nifurtimox – given orally. Used as a component of NECT and given as multiple infusions.

Treatment for stage one infections of rhodesiense African Trypanosomiasis:

Suramin – administered intravenously. The medicine works by causing parasites to lose energy and eventually killing them off.

Treatment for stage two infections of rhodesiense African Trypanosomiasis:

Melarsoprol – also administered intravenously. The drug is derived from arsenic and has many adverse effects on patients including reactions at the injection site. It is a highly toxic compound that is exclusively used to treat stage two rhodesiense African Trypanosomiasis.

People suffering from the effects of African Trypanosomiasis will likely require treatments for subsequent health problems caused by having the disease such as fluids for dehydration and treatment for malnutrition, vitamin deficiencies or wasting.

Outlook for African Trypanosomiasis

After receiving treatment, people who have had African Trypanosomiasis need to be monitored to check their recovery and make sure they do not relapse. Ideally, this should be done for the next two years following treatment and may include the need for a spinal tap to check spinal fluid for any anomalies. This is necessary because:

These parasites are able to remain in the host’s body and reproduce the disease several months after treatment.
Being infected with the African sleeping sickness does not provide lifelong immunity. Patients may become reinfected with African Trypanosomiasis.

Treating African Trypanosomiasis can be a complex and intense process that may require the administration of multiple drugs that must be administered and stored correctly. This means it is important that anyone treating such patients is adequately trained and experienced.

The rural location of many of these cases, plus the fact that they often occur in impoverished areas that lack infrastructure, adds additional layers of difficulty to treating patients. Various organisations including the WHO and Médecins Sans Frontières have been working to treat and reduce cases of African Trypanosomiasis over the years. The WHO want to have the disease eradicated (zero transmission) by 2030. Cases of African Trypanosomiasis have remained on a downward trajectory since 2017, with less than 1,000 cases per year reported between 2018 and 2020. Due to the role animals play in infection, a comprehensive, multi-tiered approach is necessary to get rid of African Trypanosomiasis altogether, as well as investments in providing healthcare to inhabitants in rural, sub-Saharan Africa.