ArticlesSerious reactions after mass treatment of onchocerciasis with ivermectin in an area endemic for Loa loa infection
Introduction
Onchocerciasis is a major public-health and socio-economic problem in many rural areas of Africa. In the 19 endemic countries outside the area of the Onchocerciasis Control Progamme in West Africa (OCP), some 94·5 million people are exposed to the risk of infection with Onchocerca volvulus, and more than 15 million are infected.1 In parts of 12 of these countries, Loa loa infections are also endemic.
Ivermectin has proven to be a safe microfilaricide and microfilarial suppressant, suitable for the mass treatment and control of onchocerciasis;2, 3, 4, 5, 6 and the manufacturer, now provides the drug free of charge for the treatment and control of onchocerciasis in endemic countries. Mass ivermectin distribution programmes are now being implemented in most endemic countries. In December, 1995, the World Bank, in cooperation with WHO, the ministries of health of the participating countries, and several non-governmental development organisations, launched the African Programme for Onchocerciasis Control (APOC), which aims to develop self-sustaining, countrywide, community-based ivermectin treatment (CBIT) programmes in the 19 endemic African countries outside the OCP.7
APOC's strategy is to deliver ivermectin by community-based distributors supervised only by monitoring teams. In areas where loiasis is also endemic, some cases of encephalopathy have been recorded after treatment with ivermectin.8, 9, 10 These patients had very high L loa microfilaraemia and L loa microfilariae in cerebrospinal fluid (CSF), suggesting that ivermectin may occasionally provoke an L loa encephalopathy similar to that seen after treatment of loiasis with diethylcarbamazine.11
The aims of this study were to evaluate the incidence of serious reactions after treatment with ivermectin in an area of Cameroon where onchocerciasis and loiasis are both endemic, and to record the relation between serious reactions and the intensity of pretreatment L loa microfilaraemia.
Section snippets
Patients and methods
The study protocol, which was approved by the Ministry of Public Health of Cameroon and by WHO, involved 1-week follow-up of a cohort of people treated with ivermectin. The study was conducted in 106 villages of the Lékié Division (Central Province, Cameroon; figure 1), where 40–95% of the residents were infected with O volvulus, and 10–33% had L loa microfilaraemia (MB, unpublished data). The area was also endemic for the minimally pathogenic Mansonella perstans. The age and sex distribution
Results
17 877 people were treated; age and sex distributions were close to those of the total population, although there was a slight over-representation of children aged 10–14 years, and a slight under-representation of women aged 15–39 and of men aged 20–54. 6415 (35·9%) adults and 8261 children (46·2%) received their first filaricidal treatment; 2823 adults (15·8%) and 378 children (2·1%) had a history of previous filaricidal treatment (ie, either ivermectin or, for 154 of the adults,
Discussion
Ivermectin has proven to be a safe drug for onchocerciasis control, and can be delivered by small monitoring teams in most endemic areas. In 1995, more than 7 million people exposed to O volvulus were treated. Treated populations are well aware that reactions may occur, but the drug's popularity is high. However, the fall-off in attendance we noticed during the present study after the occurrence of several serious reactions suggests that such events might modify the target populations' attitude
References (21)
- et al.
Efficacy and tolerance of ivermectin in human onchocerciasis
Lancet
(1982) - et al.
Improvement in severe onchocercal skin disease after a single dose of ivermectin
Am J Med
(1991) - et al.
Reduction in incidence of optic nerve disease with annual ivermectin to control onchocerciasis
Lancet
(1993) The African Programme for Onchocerciasis Control: preparing to launch
Parasitol Today
(1995)- et al.
Severe adverse reaction risks during mass treatment with ivermectin in loiasis-endemic areas
Parasitol Today
(1996) - et al.
The status of ivermectin in the treatment of human onchocerciasis
Am J Trop Med Hyg
(1989) - et al.
Effect of repeated treatments with ivermectin on the incidence of onchocerciasis in Northern Cameroon
Am J Trop Med Hyg
(1995) Ivermectin: possible neurotoxicity
WHO Drug Information
(1991)- et al.
Effets secondaires du traitement de la loase hypermicrofilarémique par l'ivermectine
Bull Soc Path Ex
(1995)
Cited by (482)
Cases of Loiasis Among a Congolese Family: Screening for Loiasis Among Newly Arrived Refugees From Endemic Areas
2023, Journal for Nurse PractitionersThe Filariases
2023, Manson's Tropical Diseases, Fourth Edition