The reasons why flea infestations remain frequent in companion animals despite the considerable number of anti-flea products is of interest. Successful flea control relies mainly on the use of effective anti-flea products and pet owners adhering to treatment recommendations. When flea infestations continue to persist despite the application of a potent anti-flea product, lack of efficacy may be suspected. In this article, the basics of flea biology and impact of flea infestation on the host are summarised. In addition, the factors that can result in ineffective treatment and control of flea infestation are discussed. Better understanding of the possible reasons can help to inform clinical practice and avoid treatment failures.

Hany Elsheikha -

Serena Wong -

Ian Wright -