Diagnosis and management of onyalai

Onyalai

Onyalai is an acquired form of immune thrombocytopenia which differs clinically, epidemiologically and immunologically from idiopathic thrombocytopenic purpura (Table 4). The clinical hallmark is haemorrhagic bullae on the mucosa of the oronasopharynx. Haemorrhage from ruptured bullae, epistaxis or gastrointestinal bleeding is severe and may cause shock and death. The disease is limited to some black populations of central southern Africa, with a recorded incidence of one per 660 inhabitants per year in the Kavango territory of Namibia. The majority of patients demonstrate both IgG and IgM serum platelet antibodies and serum platelet glycoprotein IIb/IIIa autoantibodies. Chronic thrombocytopenia often ensues and recurrent episodes of clinical bleeding are common. Treatment directed at the prevention of haemorrhagic shock reduced the mortality rate in the acute phase from 9.8 to 2.8%. Standard dose prednisolone does not increase the platelet count. Vincristine sulphate may benefit some patients and splenectomy is indicated in patients with severe uncontrollable haemorrhage. High dose intravenous gammaglobulin may be followed by a rise in the platelet count and cessation of haemorrhage. The aetiology is unknown. The possible aetiological role of mycotoxins from contaminated millet, sorghum or maize requires further investigation.

Onyalai at Rundu, Namibia 1981-1988: age, sex, morbidity, mortality and seasonal variation of 612 hospitalized patients

Of 51,263 admissions to Rundu State Hospital in Namibia between 1981 and 1988, 612 (1.19%) were diagnosed as onyalai. The annual incidence varied between 0.96% and 1.66% of all admissions. The female to male ratio was 3:2. The mean age at presentation was 24.8 years (range 6 months to 80 years) and the mean hospital stay (and duration of clinical bleeding) for the years 1981 to 1982 and 1985 to 1988 was 7.68 d (range 1-38 d). Although the highest number of cases occurred during the months March, April and May a statistically significant monthly variation was not found. The treatment policy of commencing intravenous fluid on admission and a blood transfusion whenever the haemoglobin dropped below 10 g/dl in patients with active bleeding was associated with a mortality rate of 2.78% compared to 9.8% in cases recorded up to 1981.