TABLE 5.

Key reports of field resistance or therapeutic failure of PZQ

Species	Country	Yr	Sample size	Treatment(s)	Outcome measure	Reference
S. mansoni	Senegal	1991	422	40 mg/kg	12 wk after treatment, cure rate only 18%, antigen detection positive in 90% of individuals; low cure rates may be due to intense transmission and/or development immune responses	95
	Egypt	1994	1,607	1 dose of 40 mg/kg, 3 successive doses of 40, 40 and 60 mg/kg	1–2.4% of villagers treated could not be completely cured of infection, and 3 of every 1,000 treated villagers may harbor parasites that can tolerate high doses of PZQ; extensive use of PZQ has not resulted in dramatic change in its efficacy	97
		2005	1,405		Compared with results obtained in 1994 in same villages, decreased prevalence and intensity of infections; first treatment resulted in normal cure rate (73–92%); after 3 successive doses, no uncured patients; drug failure did not increase over 10 years of therapeutic pressure in these villages	99
S. hematobium	Malawia	1995	1	∼40 mg/kg (30% was spit up)	3 doses of PZQ necessary to cure infection; concomitant Giardia lamblia infection might have caused malabsorption of drug; repeated courses of therapy may be necessary to cure infection, and both parasite and host factors should be considered if infection persists; 7 treatments necessary to eliminate eggs from parasites	100
	Senegala	2006	2	40 mg/kg	Repeated standard treatment failed to clear infection	102
S. japonicum	Sichuan Province, China	1985	185	2 × 40 mg/kg	Low no. of treatment failures (only 1 remained infected); good compliance with treatment; PZQ remains effective against this schistosome	106
		2010	584		6 wk after treatment, 95% had no detectable eggs, 3% were still excreting eggs, and 2nd dose of drug was given; no detectable eggs were observed 6 wk after 2nd dose; efficacy of PZQ still high; no evidence of resistance detected	108
		2012	43	Single oral dose of 40 mg/kg, 30 mg/kg for 2 days	6 wk after second treatment, eggs not found were found in infected villagers; no evidence of resistance	110

^aTravelers from this area of endemicity.