A disease transmitted to humans by several species of tsetse fly belonging to the genus Glossina

Cause

• Two types of trypanosomes (a protozoa) spread through the bite of tsetse fly:

- Trypanosoma rhodesiense (mostly in the Central and Eastern regions)

- Trypanosoma gambiense (mostly in West Nile region)

Clinical features

• May be history of tsetse fly bite
• May be swelling at site of bite after 7-14 days
• Headache not responding to common analgesics
• Fever
• Lymphadenopathy (generalised)
• Weight loss
• At later stage: sleepiness (T. gambiense)
• Coma and death if not treated

Differential diagnosis

• Malaria
• TB
• Meningitis
• AIDS

Investigations

Blood: slides for trypanosomes
CSF: for trypanosomes
Aspirate from chancre or lymph node: for trypanosomes

Management

This is based on the findings of the CSF analysis. To determine the drug of choice, the disease is divided into two stages: early and late stage

Management of early stage

CSF is normal, ie.

• Lymphocytes ≤ 5 cells/cubic millimetre

• Total protein <37mg/dL (by dye-binding protein assay) or <25mg/dL (by Double Standard & Centrifuge Method)

• Absence of trypanosomes (by Double Standard and Centrifuge Method)

Treatment for early stage (see Table 1 over)
HC4

T. rhodesiense:

suramin IV

T. gambiense:

suramin IV

- in onchocerciasis-free areas or pentamidine 4% or 10% IM

- in onchocerciasis-endemic areas or if the drug has not been used locally for prophylaxis

Table 1: Treatment schedule for early stage

T. rhodesiense or T. gambiense (adult 50kg and over)

Management of late stage (CSF is abnormal)
HC4

- see Table 2 below for detailed dose regime

T. rhodesiense:

day 0 and 2: suramin IV then from day 4:
melasorprol 3.6% IV
plus oral corticosteroids

T. gambiense:

preferably (if available) day 0 and day 2 start with: suramin IV

or (in onchocerciasis-endemic areas):

pentamidine IM (day 0, 1 and 2 - as in Table 1 above)

then from day 4 give:

melarsoprol 3.6% IV

plus oral corticosteroids

Note:

suramin: do not use this drug for early or late-stage T. gambiense treatment in onchocerciasis-endemic areas as it may cause blindness in any onchocerciasis-infected patients by killing the filariae in the eye

- use pentamidine instead

♦ corticosteroids: should be given to patients with late trypanosomiasis on melarsoprol who may have hypoadrenalism - the steroids may also reduce any drug reactions

Prevention

• Trapping of tsetse flies

• Clearing of bushes around homes and paths

• Early detection and treatment of cases

• Provision of latrines so that people do not go into the bush where they are likely to come into contact with tsetse flies

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Notes for Table 2 (opposite)

Cortisone:

- do not give this after day 24 even though the melarsoprol treatment is not yet complete

- if prednisolone is used instead of this, the anti-inflammatory action is similar but the correction of the hypoadrenalism will be much less marked

Table 2: Treatment schedule for late stage

T. rhodesiense or T. gambiense (adult 50kg and over)

Child doses: calculate using body weight as follows:

• suramin: 20mg/kg
• pentamidine: 4mg/kg
• melarsoprol: weight (kg)/60 x adult dose