Volume 81, Issue 6
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


The main risk factor of post-ivermectin serious adverse events (SAEs) is the presence of a high microfilaremia. However, the majority of patients with such high loads do not develop SAEs, suggesting that co-factors may be involved. An infection with simian parasites, whose microfilariae show a nocturnal periodicity, might be such a co-factor. The periodicity of microfilariae was compared, using cosinor methodology, in 4 patients who had developed a post-ivermectin neurologic SAE, 4 patients who had experienced a non-neurologic SAE, and 14 control individuals. The periodicity was similar in all three groups, with a peak of microfilaremia occurring between 12:30 and 2:00 . The results of this study, which for the first time characterizes the periodicity of microfilariae mathematically, suggest that post-ivermectin SAEs are not related to an infection with a simian strain.


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  • Received : 23 Jun 2009
  • Accepted : 30 Jul 2009

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