Filariasis infection is a probable cause of implantation failure in in vitro fertilization cycles.

OBJECTIVE: To describe a parasitic infection that probably affected the implantation of good-quality embryos in an in vitro fertilization (IVF) cycle.
DESIGN: Case report.
SETTING: Tertiary care center in a university hospital. PATIENT(S): A 36-year-old Caucasian female with primary unexplained infertility. The patient underwent two cycles of IVF with good-quality embryos transferred; however, no pregnancy ensued despite adequate luteal support. INTERVENTION(S): In vitro fertilization cycles, CBC, blood smear, evaluation for eosinophilia including serological evaluation for parasitic infections. MAIN OUTCOME MEASURE(S): Pregnancy. RESULT(S): Following treatment for filariasis, a repeat IVF cycle using the same stimulation protocol yielded a full-term pregnancy. CONCLUSION(S): This case is of particular importance because, to our knowledge, it is the first to describe a parasitic infection that probably affected the implantation of good-quality embryos in IVF cycles.