Persistent eosinophilia among 21 historic cases of Strongyloides stercoralis infection: a case for routine follow-up and repeat treatment

Background: Strongyloidasis affects more than 100 million people worldwide and causes persisting infection. Methods: We retrospectively reviewed 21 cases of parasitologically confirmed Strongyloides stercoralis infection at our centre. Results: We found four individuals who had eosinophilia (>0.5x10(9)/litre) more than 6 mo after treatment. Conclusions: This may represent ongoing or relapsed infection. Our data support the need for continued follow-up of treated individuals, particularly those with abnormal host defences who are at risk of severe forms of the disease.