Fryauff D J, Baird J K, Awalludin M, Jones T, Subianto B, Richie T L, Tjitra E, Wignall F S, Hoffman S L
U.S. Naval Medical Research Unit No. 2, Jakarta, Indonesia.
Am J Trop Med Hyg. 1997 Feb;56(2):137-40. doi: 10.4269/ajtmh.1997.56.137.
Extended chemoprophylaxis against endemic malaria raises concern with regard to susceptibility after ceasing use of the drug. In this study, we measured attack rates of malaria among adult men for 28 weeks after they ended one year of prophylaxis using either weekly chloroquine (5 mg base/kg, n = 20), daily primaquine (0.5 mg base/kg, n = 30), or a placebo of primaquine (n = 41). The 28-week incidence densities, times to parasitemia, parasite densities, and symptoms of primary post-prophylaxis infections were not significantly different among the former primaquine, chloroquine, and placebo groups. However, the incidence of Plasmodium falciparum infection in the post-chloroquine group was significantly greater than in the post-primaquine group during the first (P = 0.03) and second (P = 0.02) months post-prophylaxis. Six of 10 primary P. falciparum and three of 10 P. vivax infections occurred in the former chloroquine group within one month after ending prophylaxis and the mean time to infection was 30-35 days. In contrast, only one P. falciparum and no P. vivax infections occurred during the first month after ending primaquine prophylaxis. The mean time to first parasitemia by either species of malaria parasite in this group was 72-77 days. There was no indication that daily use of primaquine for one year placed subjects at greater risk of malaria infection or to more severe clinical symptoms of malaria than subjects who had taken placebo or chloroquine, despite the potential for some degree of immunity to have been acquired in these latter two groups during the year-long prophylaxis period. The results do suggest that chloroquine suppressed P.falciparum infections until drug levels decreased, and that primaquine had effectively prevented the establishment of liver-stage parasites.
针对地方性疟疾延长化学预防时间引发了人们对停药后易感性的担忧。在本研究中，我们测量了成年男性在停止使用每周一次氯喹（5毫克碱基/千克，n = 20）、每日一次伯氨喹（0.5毫克碱基/千克，n = 30）或伯氨喹安慰剂（n = 41）进行一年预防后28周内的疟疾发病率。前伯氨喹组、氯喹组和安慰剂组在28周的发病密度、出现寄生虫血症的时间、寄生虫密度以及预防后初次感染的症状方面没有显著差异。然而，在预防后的第一个月（P = 0.03）和第二个月（P = 0.02），氯喹组恶性疟原虫感染的发生率显著高于伯氨喹组。10例初次恶性疟原虫感染中有6例以及10例间日疟原虫感染中有3例发生在氯喹组停药后一个月内，感染的平均时间为30 - 35天。相比之下，在停止伯氨喹预防后的第一个月内仅发生了1例恶性疟原虫感染，没有间日疟原虫感染。该组中任何一种疟原虫首次出现寄生虫血症的平均时间为72 - 77天。没有迹象表明，与服用安慰剂或氯喹的受试者相比，每日服用伯氨喹一年会使受试者面临更高的疟疾感染风险或出现更严重的疟疾临床症状，尽管后两组在长达一年的预防期内可能获得了一定程度的免疫力。结果确实表明，氯喹在药物水平下降之前抑制了恶性疟原虫感染，并且伯氨喹有效地预防了肝期寄生虫的形成。
