REFERENCE TO APPEARANCE OF NEW NODULES AND PARASITE CONTENT*

Abstract. To determine the rate of appearance of new nodules during a specified period, a follow-up study on onchocercomas that had been removed was carried out in San Vicente Pacaya, Guatemala, between June 1976 and April 1977. Incidence rate, or rate of nodules appearing in initially negative subjects, was studied in relation to the degree of endemicity. Rates in a period of 7—8months in high, medium, and low endemic areas were 0.23 1, 0.083, and 0.022, respectively. The rate of nodule appearance in persons nodulectomized, or rate cfnodulesappearinginsubjectswhoweresurgicallyrenderednegativeduringthefirstsurvey, was 45.3%, 36.4%, and 4.5 % in those areas. The highest rate of nodule appearance was observed in patients with microfilariae in both the skin and nodules, followed by patients with either microfilariae or nodules. In highly endemic areas, new nodules appeared in 13.2% of persons without microfilariae or nodules, while in low endemic areas even patients with nodules earlier were less likely to have developed new ones. The performance of the nodu lectomy teams (brigadas) was evaluated by confirming the worms in nodules. By gross e