Contents
Introduction
African trypanosomiasis, also known as sleeping sickness, is an insect-borne parasitic disease of humans and other animals caused by protozoa Trypanosoma brucei usually transmitted by the bite of an infected tsetse fly, most common in rural areas.
History


Epidemiology

Transmission
- Vector transmission (M/C)
- Other forms:
- Mother-to-child infection
- Laboratories: accidental infections
- Blood transfusion
- Sexual contact
Life cycle:

- Two types that infect humans:
- Trypanosoma brucei gambiense (TbG) (98% cases)
- Trypanosoma brucei rhodesiense (TbR)
Vector:
- Tsetse fly (painful bite)

Clinical features
First stage “hemolymphatic phase”
- Fever, headaches, joint pains, and itching
- Fever is intermittent, with attacks lasting from a day to a week, separated by intervals of a few days to a month or longer
- Invasion of the circulatory and lymphatic systems by the parasites:
- Lymphadenopathy
- Winterbottom’s sign (Tell-tale swollen lymph nodes along the back of the neck)
- Chancre (red sore) develops at the location of the tsetse fly bite
- If untreated, the disease overcomes the host’s defenses and can cause more extensive damage:
- Anaemia, endocrine, cardiac, and kidney dysfunctions
Second phase “neurological phase”
Begins when the parasite invades the central nervous system by passing through the blood-brain barrier (BBB)
Damage caused in the neurological phase is irreversible
- Disruption of the sleep cycle (leading symptom, leading to the name ‘sleeping sickness‘)
- Disorganized and fragmented 24-hour rhythm of the sleep-wake cycle (eg. daytime sleep episodes and nighttime periods of wakefulness)
- Other neurological symptoms:
- Confusion, tremor, general muscle weakness, hemiparesis, and paralysis of a limb
- Parkinson-like movements
- Due to non-specific movement disorders and speech disorders
- Psychiatric symptoms (can sometimes dominate the clinical diagnosis):
- Irritability, psychotic reactions, aggressive behaviour, or apathy
Untreated infections:
- Progressive mental deterioration leading to coma
- Systemic organ failure and death (within months)
Diagnosis
Investigations
Detection of trypanosomes:
- Samples for study:
- Chancre fluid, lymph node aspirates, blood, bone marrow, and CSF (during neurological stage)
- Preparation of samples:
- Wet preparation (can be used to look for the motile trypanosomes)
- Fixed (dried) smear (stained using Giemsa’s or Field’s technique and examined under a microscope)
- Concentration of samples (prior to microscopic examination):
- Blood samples:
- Centrifugation followed by examination of the buffy coat
- Mini anion-exchange/centrifugation
- Quantitative buffy coat (QBC) technique
- Other samples:
- Centrifugation followed by examination of the sediment
- Blood samples:
Serological tests:
- Dried blood:
- Micro-CATT
- Whole blood samples:
- wb-CATT
- wb-LATEX
Management
First stage
- T. b. gambiense: IV/IM pentamidine
- T. b. rhodesiense: IV suramin
Second stage
- T. b. gambiense:
- First-line treatment regimens:
- Nifurtimox + eflornithine, or
- Nifurtimox-eflornithine combination treatment (NECT), or
- Eflornithine (alone)
- First-line treatment regimens:
- IV melarsoprol
- T. b. rhodesiense (1st-line)
- T. b. gambiense (2nd-line)