Touchdown-touchup nested PCR for low-copy gene detection of benzimidazole-susceptible Wuchereria bancrofti with a Wolbachia endosymbiont imported by migrant carriers

► Microfilaremia of the Wuchereria bancrofti-infected patient harbors the most viable Mf. ► Drug-responsive microfilaremia harbors a diverse range of viable and non-viable Mf. ► The Mf are the only target of antifilarial drugs such as DEC plus albendazole. ► Gene detection unveils drug responses affecting Mf with sessile Wolbachia. ► Locus-specific TNPCRs serve as coupled Wuchereria-Wolbachia gene amplifications.