37.3.3 Clinical manifestations and diagnosis of onchocerciasis
The clinical manifestations of onchocerciasis are the result of inflammation against the dead microfilaria. The most common clinical manifestations include skin rashes, lesions, intense itching, loss of the colour of the skin, and nodule formation (Figure 37.15a). Microfilaria also migrate to the eye, and causes scarring of the cornea (the covering of the eyeball), which leads to sight defects and ultimately blindness (Figure 37.15b).
The itching and disfiguring nodules and blindness are sources of great distress to patients, who may be stigmatised and rejected by their communities.
Diagnosis of onchocerciasis is made by clinical examination. If you suspect that a patient may be infected, you should make a referral for laboratory confirmation and treatment. Microscopic investigation of a skin snip (taking samples from the skin) can identify the microfilaria and confirm the diagnosis.