Three probable cases of Loa loa encephalopathy following ivermectin treatment for onchocerciasis.

Abstract

Over the past nine years, more than 12 million people exposed to Onchocerca volvulus infection have received at least one dose of ivermectin, almost all without serious adverse reactions. Since 1991, however, several cases with neurologic manifestations, including coma, have been reported after ivermectin treatment of persons infected with O. volvulus who also had concomitant Loa loa infection with very high microfilaremia (Ͼ 50,000 microfilariae/ml of blood). In 1995, four criteria were established to define probable cases of Loa encephalopathy temporally related to treatment with ivermectin (PLERI). The present paper describes three PLERI cases recorded in Cameroon and compares them with two others reported previously. Disorders of consciousness began 3-4 days after treatment. The objective neurologic signs were variable. The conditions improved favorably in three patients who benefited from early hospitalization and good nursing; their disorders of consciousness lasted only 2-3 days; the results of clinical examination became normal after one month and electroencephalographic abnormalities disappeared after 5-7 months. Conversely, late diagnosis and delay in proper management in two others probably led to worsening of the condition and to fatal outcome related to the usual complications of coma. In addition to these cases, patients w with high Loa microfilaremia also developed milder neurologic manifestations causing functional impairment lasting for at least one week after treatment. Before launching mass ivermectin distribution programs to control onchocerciasis in central Africa, communities in which the intensity of concomitant L. loa microfilaremia is high need to be identified, and specific educational measures and monitoring strategies should be developed and applied before they are treated.

First case of ivermectin-induced severe hepatitis

“…Ivermectin is used for treatment in many diseases, including loiasis, scabies, onchocerciasis and strongyloidiasis. In the treatment of onchocerciasis with ivermectin, where L. loa is endemic, encephalitis has been reported (Boussinesq et al, 1998;Ducorps et al, 1995;Gardon et al, 1997). In our patient the results of the liver biopsy were compatible with drug-induced hepatotoxicity.…”

Clinical Features of Imported Loiasis: A Case Series from the Hospital for Tropical Diseases, London

“…20 Rapid clearance of microfilaremia is supposedly responsible for the development of encephalopathy, but only a few studies have examined pretreatment microfilarial density in patients with encephalopathy. 21,22 It has been suggested that a reduction of more than 30,000 mf/mL in 3 days may increase the risk of encephalopathy occurring. 23 This study suggests that raised CRP before treatment may also be a predictive risk factor for mild reactions.…”

Microfilarial distribution of Loa loa in the human host: population dynamics and epidemiological implications

“…However, individuals harbouring high microfilaraemias may, exceptionally, develop serious spontaneous neurological or renal complications (Cauchie et al 1965 ;Zuidema, 1971). More significantly, it is well known that high microfilarial (mf) loads are associated with a risk of developing neurological serious adverse events (SAEs) after treatment with the filaricidal drugs diethylcarbamazine (DEC) and ivermectin (Fain, 1978 ;Carme et al 1991 ;Gardon et al 1997 a ;Boussinesq et al 1998). Thus, following ivermectin treatment, it has been demonstrated that individuals presenting with high mf loads (>8000 mf/ml), and those with very high mf loads (>30 000 mf/ml) had, respectively, an increased risk of developing severe adverse reactions without neurological involvement, and SAEs (Gardon et al 1997 a).…”