In a population survey in 1970/72 the prevalence of head nodules was found to be 1.7% in 1098 cases of onchocerciasis in the rain-forest and 0.6% in 1128 cases in the Sudan-savanna of Cameroon. In a follow-up survey in the same villages 3-4 years later more attention was given to the detection of head nocules, and the corresponding prevalences were 5.5 and 5.0%. In the follow-up survey a strong associated was demonstrated between the presence of head nodules and lesions of both the anterior and posterior segments of the eye. The relative risks of having eye lesions in patients with head nodules compared with those without were 2.9 and 7.5 in the rain-forest and savanna respectively. In a group of 483 clinic cases with ocular onchocerciasis from the savanna palpable head nodules were detected in 23.6%, and in a further 140 selected cases from the same area with posterior segment eye lesions, head nodules were detected in 31.4%. Confirmation of the onchocercal origin of the nodules was obtained in doubtful cases by biopsy. Many head nodules probably remain undetected in onchocerciasis surveys. They are often very small, flat, and hard, and tightly adherent to the under-lying periosteum, and the patient will often point out the presence of a nodule even when none has been detected after careful examination. The presence of a head nodule has long been one of the recognized "risk factors" associated with a high prevalence of blindness in Central America, but there have been no detailed studied in African onchocerciasis. A trial is in progress to assess the effect of nodulectomy on the development of ocular lesions.

39 patients (Group A) with ocular onchocerciasis in the Sudan-savanna of north Cameroon were given 4-6 g of suramin and followed in detail over 1-2 years. 39 other patients (Group B) received suramin followed 2 weeks later by a 6-7 day course of diethylcarbamazine (DEC). A further 18 patients (Group C) received placebo injections and were followed in the same way by the same observers. Suramin caused serious general reactions among the 100 patients who started the course - 1 case of stomatitis, 1 exfoliative dermatitis, and several cases of severe prostration, among which 2 ended fatally. These reactions underline the urgency for further studies on the toxicity of suramin, which is without doubt an efficient macro- and micro-filaricidal drug. Changes which occurred in the ocular lesions are described in detail. There was an initial aggravation of punctate and sclerosing keratitis, and sometimes a serious aggravation or development of anterior uveitis, corresponding to the peak microfilaricidal effect of the drug. The possibility of a simultaneous adverse effect on the optic disc is discussed. Despite these reactions, which might have been avoided by prior elimination of microfilariae by DEC, the eyes were in general quieter at 3 months and thereafter than before treatment. However, no posterior segment lesion improved after suramin, and the majority remained unchanged. The findings at the end of the trial were as follows: No. of lesions (see article).

1.1. The effects of 3% diethylcarbamazine eye drops (Onchozan) on O. volvulus microfilariae in the cornea and in the anterior chamber are described in 9 Cameroonian subjects.2.2. The therapy tended to reduce the numbers of microfilariae seen in the anterior chamber, but they were not completely eliminated. It also led to death of microfilariae in the cornea following an initial invasion.3.3. Onchozan drops, innocuous in themselves, caused anterior uveitis in some heavily infected onchocerciasis patients, and their administration requires adequate ophthalmological supervision.