云南省恶性疟原虫对氯喹抗性的纵向监测

应用ＷＨＯ推荐的体外微量测定法于停用氯喹前的１９８１年及停药后的１９８４、１９８８—１９９０和１９９２年在云南省南部的勐腊县测得恶性疟原虫对氯喹的抗性率分别为９７．４％、１００％、９６．１％及９３．７％；ＩＤ５０依次为１７０、１３２、１２５及１１０ｎｍｏｌ／Ｌ，ＩＤ９５为１０００、７４０、７０７及５７６ｎｍｏｌ／Ｌ；平均抑制量分别为５５．４、４６．７、４５．８及３５．４ｐｍｏ１／井。与１９８１年测得结果相比，抗性率无明显变化；ＩＤ５０分别下降２２．３％（Ｐ＜０．０５）、２６．４％（Ｐ＜０．０５）及３５．３％（Ｐ＜０．０１），ＩＤ９５依次下降２６．０％（Ｐ＜０．０５）、２９．３％（Ｐ＜０．０５）及４２．４％（Ｐ＜０．０１）。平均抑制量分别下降１５．７％（Ｐ＞０．０５）、１７．３％（Ｐ＜０．０５）及３６．１％（Ｐ＜０．０１）。提示云南南部恶性疟原虫对氯喹的抗性并不稳定，而是随药物压力的下降而降低。     

伯氏疟原虫氯喹敏感株和抗性株中的氯喹积聚和排出

目的探测进入抗氯喹疟原虫中的氯喹量较敏感株低的原因是受阻于感染的红细胞，还是疟原虫自身，以及抗氯喹疟原虫是否具有快速排出氯喹的特点。方法：给两株感染小鼠ｉｇ氯喹，用高压液相（外标法）检测感染红细胞和疟原虫中的氯喹量。结果：ｉｇ氯喹４．０６ ｍｇ／ｋｇ与４００ｍｇ／ｋｇ氯喹３ｈ后，敏感株感染红细胞和抗氯喹株感染红细胞中的氯喹量无明显差异，而抗氯喹疟原虫中的氯喹量，两个剂量组分别较敏感的低５４．０％与４２．１％（Ｐ＜０．００１）。比较ｉｇ氯喹３ｈ与７ｈ后疟原虫积聚的氯喹量，敏感株两者相同，抗性株７ｈ后不仅无明显减少，相反地上升（０．４５２±０．０７９ｎｍｏｌ／ｍｇ蛋白与０．５５９±０．１２４ｎｍｏｌ／ｍｇ）蛋白（Ｐ＜０．０２）。结论：进入抗氯喹疟原虫中的氯喹量低，其受阻部位是在疟原虫本身而不是在感染的红细胞，未发现抗氯喹疟原虫快速排出氯喹。     

我国恶性疟原虫对抗疟药敏感性的现状

目的：了解恶性疟原虫对各种常用抗疟药的敏感性，以指导合理应用抗疟药。方法：采用ＷＨＯ标准体外微量法。结果：甲氟喹和奎宁分别测定３６例和３３例，未发现抗性病例。氯喹、氨酚喹和哌喹抗性率分别为８４．６％、８６．１％和３８．０％。有８．３％病例对咯萘啶有抗性，少数病例对青蒿素类药物敏感性下降。结论：云南和海南两省恶性疟原虫对氯喹、氨酚喹和哌喹有高度抗性，但停用氯喹后，恶性疟原虫对氯喹敏感性有所恢复。对哌喹抗性率和抗性程度呈现逐渐上升趋势。对咯萘啶和青蒿素类药物的敏感性在逐渐降低。上述抗疟药抗性之间有一定交叉关系。     

西咪替丁抗疟作用的研究Ⅱ.西咪替丁对鼠疟的影响

西咪替丁（ＣＭＤ）４ｄ抑制法抗鼠疟作用结果显示：在剂量为５０ｍｇ／ｋｇ·ｄ、１００ｍｇ／ｋｇ·ｄ和２００ｍｇ／ｋｇ·ｄ时，该药对伯氏疟原虫氯喹敏感株、抗性株及约氏疟原虫氯喹敏感株感染小鼠的红内期疟原虫，均有明显的抑制作用，３组平均抑制率分别为６４．９５％、７７．９７％和５８．１６％。ＣＭＤ对伯氏疟原虫氯喹抗性株的抑制作用显著高于伯氏疟原虫氯喹敏感株（Ｐ＜０．０５）和约氏疟原虫氯喹敏感株（Ｐ＜０．０１）。     

中缅边境西段缅甸恶性疟原虫对氯喹,青蒿琥酯及咯萘啶的敏…

应用Ｒｉｅｃｋｍａｎｎ体外微量法测得中缅边境西段缅甸境内感染的恶性疟原虫对氯喹及我国抗疟新药青蒿琥酯及咯萘啶的抗性率分别为１００％、１４．３％及１９．０％，半数抑制量依次为２４９．４、４．２及１２．１ｎｍｏｌ／Ｌ。３例抗青蒿琥酯恶性疟原虫对氯喹和咯萘啶的ＩＤ５０分别为３３５、６ｎｍｏｌ／Ｌ和４３．１ｎｍｏｌ／Ｌ；４例抗咯萘啶恶性疟原虫对氯喹和青蒿琥酯的ＩＤ５０分别为２６０．１ｎｍｏｌ／Ｌ和５．０ｎ     

停用氯喹12年抗氯喹恶性疟原虫对氯喹抗性的变化

由于海南省恶性疟原虫对氯喹普遍产生了抗性,所以于1979年开始,在全岛范围内停止使用氯喹防治恶性疟。为了了解停止使用氯喹后恶性疟原虫对氯喹抗性的消长情况,作者以该省乐东县为观察点,于1981—1991年间,每隔2—3年测定1次恶性疟原虫对氯喹的敏感性。结果发现,停止使用氯喹后,恶性疟原虫对氯喹的抗性呈逐渐降低趋势,体外法测得的抗性率由1981年的97.9％,降至1991年为60.9％(P<0.001),完全抑制裂殖体形成的平均剂量由1981年的10.46pmol/μl,降至1991年的3.02pmol/μl(P<0.001),需用大剂量(6.4pmol/μl)才能完全抑制裂殖体形成的病例比例,由1981年的83.3％,降为1991年的17.4％(P<0.001),而小剂量(1.6pmol/μl)即可抑制的病例比例,却由1981年的4.2％增加到1991年的60.8％(P<0.001)。体内法测得的抗性率,由1981年的84.2％,降为1991年的40％(P<0.001),RⅡ和RⅢ占抗性病例比例,由1981年的59.4％,降至1991年的37.5％(0.02>P>0.01)。     

体外测定恶性疟原虫对七种抗疟药的敏感性

１９９２年应用体外微量法在中老边境测得我国境内恶性疟原虫对氯喹、哌喹、青蒿琥酯、蒿甲醚、蒿乙醚、还原青蒿素及咯萘啶抗性率，分别为９７．０％、９６．４％、１２．１％、１６．０％、６．２％、１２．５％、３４．５％；半数抑制量（ＩＤ５０）依次为１１９．０、３２０、７．２、２９５．０、７４．４、５．４及３１．９ｎｍｏｌ／Ｌ。老挝境内恶性疟原虫分离株对氯喹、哌喹及咯萘啶的抗性率分别为９／１０、８／１０及１／５；ＩＤ５０依次为１１４．０、１６６．９及１６．４ｎｍｏｌ／Ｌ；对青蒿琥酯、蒿甲醚、蒿乙醚及还原青蒿素均敏感，ＩＤ５０分别为５．０、９１．６、５６．７及４．４ｎｍｏｌ／Ｌ。结果提示境内外恶性疟原虫株对氯喹的抗性程度相似，但对哌喹的抗性程度境外明显低于境内。对青蒿琥酯、蒿甲醚、蒿乙醚及还原青蒿素的敏感性境外明显高于境内。     

中缅边境地区恶性疟原虫对7种抗疟药敏感性的体外测定

应用体外微量法检测恶性疟原虫对氯喹、氨酚喹、青蒿琥酯、还原青蒿素、蒿乙醚及咯萘啶的抗性率，我国境内的分别是９５．７％（２２／２３）、８８．９％（８／９）、１６．５％（４／２４）、２２．２％（２／９）、１１．１％（１／９）、２０．８％（５／２４）；半数抑制量（ＩＤ５０）分别为１７６、７２、６、１３、１１８、１６ｎｍｏｌ／Ｌ；ＩＤ９５依次为８３０、５１２、３４、８０、６５０、８８ｕｍｏｌ／Ｌ。缅甸境内的分别为１００％（２９／２９）、８３．３％（５／６）、１３．８％（４／２９）、１６．７％（１／６）、１６．７％（１／６）、２１．４％（６／２８）；ＩＤ５０分别为２４０、５２、６、１４、１２０、１８ｎｍｏｌ／Ｌ；ＩＤ９５为１４０８、３８４、３４、８０、６５０、９６ｎｍｏｌ／Ｌ。境内、外恶性疟原虫对奎宁均敏感，ＩＤ５０分别为６０８、４７０ｎｍｏｌ／Ｌ，ＩＤ９５为２５６０，１６９０ｎｍｏｌ／Ｌ。证实该地区恶性疟原虫对氯喹普遍存在高度抗性．且缅甸高于我国；对氨酚喹亦普遍产生抗性；对青蒿琥酯，还原青蒿素、蒿乙醚、咯萘啶有少数疟原虫产生低度抗性。抗氯喹恶性疟原虫对青蒿琥酯，还原青蒿素、蒿乙醇和咯萘啶无交叉抗性。抗青蒿琥酯恶性疟     

西咪替丁抗疟作用的研究 Ⅳ.感染疟原虫小鼠血清4种元素含量比较

应用ＩＣＰ－４００型等离子原子发射光谱仪检测感染伯氏疟原虫氯喹敏感株（Ｐ．ｂＣＱＳ）、抗性株（Ｐ．ｂＣＱＲ）和约氏疟原虫氯喹敏感株（Ｐ．ｙＣＱＳ）小鼠血清的Ｚｎ、Ｃｕ、Ｆｅ、Ｃａ４种元素含量。结果显示：与正常组比较，３株虫感染组中，Ｃｕ的含量均明显增高（Ｐ＜０．００１），Ｃａ的含量均明显降低（Ｐ＜０．００１）；Ｚｎ值在Ｐ．ｂＣＱＳ组显著降低；Ｆｅ值在Ｐ．ｙＣＱＳ组中显著增高。Ｐ．ｂＣＱＳ组与Ｐ．ｂＣＱＲ组在西咪替丁及氯喹作用下，元素变化有组间差异。     

间日疟原虫对氯喹敏感性临床研究

间日疟原虫对氯喹敏感性临床研究杨锡孟１杨马庆１黄继伟２赵风仙１１．云南省元江县医院（６５３３００）２．云南省元江县防疫站我国６０年代初开始将氯喹应用于疟疾的防治，１９７３年首次报道耿马孟定恶性疟原虫对氯喹产生抗性［１］。１９８１～１９８３年调查云南省...     

停用氯喹12年抗氯喹恶性疟原虫对氯喹抗性...

In view of the fact the resistance of Plasmodium falciparum to chloroquine occurred extensively in Hainan, a decision was made in 1979 that the use of chloroquine should be quit in the whole province. A longitudinal survey on chloroquine-sensitivity of P. falciparum was carried out during 1981-1991 to observe the variation in resistance of the parasite after the cessation of the chloroquine medication for every 2-3 years. A tendency of progressive decline of resistance was revealed. By using in vitro test, the rate of chloroquine-resistant P. falciparum dropped from 97.9% in 1981 to 60.9% in 1991 (P < 0.001). The mean dosage of chloroquine for complete inhibition of schizont formation declined from 10.46 pmol/microliters in 1981 to 3.02 pmol/microliters in 1991 (P < 0.001). The percentage of population requiring larger dosage (6.4 pmol/microliters to completely inhibit schizont formation declined from 83.3% in 1981 to 17.4% in 1991 (P < 0.001); whereas those requiring small dosage (1.6 pmol/microliters), increased from 4.2% in 1981 to 60.8% in 1991 (P < 0.001). In in vivo test, the rate of chloroquine-resistant P. falciparum decreased from 84.2% in 1981 to 40% in 1991 (P < 0.001). The proportion of RII plus RIII cases of the total resistant cases dropped from 59.4% in 1981 to 37.5% in 1991 (0.02 > P > 0.01).     

我国恶性疟原虫对氯喹抗性的消长

目的　监测停止或减少使用氯喹防治恶性疟后恶性疟原虫对氯喹抗性的变化。　方法　采用世界卫生组织 (WHO)制定的体外微量法和体内四周法 ,在停用氯喹后不同时间测定恶性疟原虫对氯喹的敏感性。　结果　海南省乐东县抱由镇体外法测定抗性率由 1981年的 97.9%降至 1997年的 2 6.7% (P <0.0 1) ,完全抑制裂殖体形成的平均药浓度由 10.46±7.14 pmol/μl 血 降至 1.63± 1.47pmol/μl 血 (P<0.0 1) ,用较高药浓度 (>6.4pmol/μl血)才能完全抑制裂殖体形成的病例所占比例由 83.3 %降为 6.7% (P<0.0 1)。体内法测定抗性率由 1981年的 84.2 %降为 1997年的 18.4% (P<0.0 1) ,三级抗性 (RⅢ )占抗性病例的比例由 5 3.1%降为 14.3 % (P<0.0 1) ,血中无性体疟原虫平均消失时间由 72.0± 2 1.6 h变为 5 0.7± 16.1 h。2 0 0 1年三亚市雅亮乡体外法测定抗性率为 5 9.8% ,平均抑制药浓度 3.5 6± 2.12 pmol/μl 血 。 2 0 0 3年乐东县福抱乡体内法测定抗性率为 62.5 % ,RI、RⅡ和RⅢ分别占抗性病例 50 %、30 %和 20 % ,无性体疟原虫平均消失时间 5 6.9± 17.2 h。云南省勐腊县体外法测定抗性率由 1981年的97.4%降至 1999年的 77.8% (P <0.0 1) ,完全抑制裂殖体形成的平均药物浓度由 17.2± 12.6 pmol/μl血降至4.4±3.1 pmol/μl(P<0.01)。2002年景洪县体外法测定抗性率为70.4%，抑制裂殖体形成的平均药物浓度为4.0±3.3 pmol/μl 血。 结论 减少或停止使用氯喹后，我国恶性疟原虫对氯喹抗性呈降低趋势，逐渐恢复了对氯喹的敏感性。     

Decreased prevalence of the Plasmodium falciparum chloroquine resistance transporter 76T marker associated with cessation of chloroquine use against P. falciparum malaria in Hainan, People's Republic of China

The use of chloroquine treatment for Plasmodium falciparum malaria was abandoned in China in 1979 because of widespread drug resistance. Subsequent studies found decreases in the prevalence of chloroquine-resistant strains. To evaluate these decreases and assess the current status of chloroquine sensitivity in Hainan, China, we determined the prevalence of the P. falciparum chloroquine resistance transporter (PfCRT) 76T marker in the DNA of blood samples collected from 1978 to 2001. Results showed the presence of PfCRT 76T in 101 of 112 samples (90%) from 1978 to 1981, 30 of 43 samples (70%) from 1986, 22 of 34 samples (65%) from 1997 to 1998, and 37 of 68 samples (54%) from 2001. The prevalence of PfCRT 76T thus progressively decreased after chloroquine was discontinued as a treatment for P. falciparum malaria (chi(2) = 5.2, P < 0.022 [1978-1981 versus 1986]; chi(2) = 7.4, P < 0.006 [1978-1981 versus 1997-1998]; and chi(2) = 28.8, P < 0.0001 [1978-1981 versus 2001]). Reduced prevalence of the PfCRT 76T marker is consistent with greater rates of chloroquine sensitivity from in vitro drug assays of blood samples in 1997 and 2001. Monitoring for continued decreases will provide valuable information for future drug-use policies in China.     

Reemergence of chloroquine-sensitive Plasmodium falciparum malaria after cessation of chloroquine use in Malawi

In 1993, Malawi became the first African country to replace chloroquine with sulfadoxine-pyrimethamine nationwide in response to high rates of chloroquine-resistant falciparum malaria. To determine whether withdrawal of chloroquine can lead to the reemergence of chloroquine sensitivity, the prevalence of the pfcrt 76T molecular marker for chloroquine-resistant Plasmodium falciparum malaria was retrospectively measured in Blantyre, Malawi. The prevalence of the chloroquine-resistant pfcrt genotype decreased from 85% in 1992 to 13% in 2000. In 2001, chloroquine cleared 100% of 63 asymptomatic P. falciparum infections, no isolates were resistant to chloroquine in vitro, and no infections with the chloroquine-resistant pfcrt genotype were detected. A concerted national effort to withdraw chloroquine from use has been followed by a return of chloroquine-sensitive falciparum malaria in Malawi. The reintroduction of chloroquine, ideally in combination with another antimalarial drug, should be considered in areas where chloroquine resistance has declined and safe and affordable alternatives remain unavailable.     

Plasmodium falciparum in Kisumu, Kenya: differences in sensitivity to amodiaquine and chloroquine in vitro

Sensitivity to amodiaquine and chloroquine was examined in 11 Plasmodium falciparum isolates from Kisumu, Kenya, and three chloroquine-resistant parasites. All 11 Kisumu isolates were sensitive to amodiaquine in vivo. Six of 10 Kisumu isolates successfully tested were more sensitive to amodiaquine in a microtest (minimal inhibitory concentration [MIC], less than or equal to 114 nM for amodiaquine vs 160 nM for chloroquine) and/or 48-hr in vitro tests (MIC, 60 nM for amodiaquine vs 100 nM for chloroquine). All nine successfully cultured Kisumu isolates had a lower 50% inhibitory dose (ID50) for amodiaquine (9.0-18.2 nM) than for chloroquine (24.9-75.4 nM) in a radioisotopic assay. Five were also more sensitive when retested in the 48-hr test. The chloroquine-resistant parasites had reduced in vitro sensitivity to chloroquine (ID50, greater than or equal to 103 nM; MIC, 300 nM) but not to amodiaquine (ID50, less than or equal to 22 nM; MIC, less than or equal to 100 nM). These data indicate that amodiaquine is more potent than chloroquine and should be evaluated for efficacy against P falciparum in areas where RI and RII chloroquine resistance occurs.     

Sensitivity of Plasmodium falciparum isolates to chloroquine in Kisumu and Malindi, Kenya

The chloroquine sensitivity of Plasmodium falciparum isolates from infected persons living in Kisumu and Malindi, Kenya, was determined in vivo and vitro. There was no evidence of chloroquine resistance in 217 patients with P. faliparum infections who underwent standard W.H.O. 7-day in vivo tests. In 71 extended 35-day in vivo tests parasitemia recurred in 14 patients on days 21, 28, or 35. Parasites isolated from these 14 persons during the following period were tested in vitro. Eight tests were successful and showed the isolates to be chloroquine sensitive in vitro, suggesting that the recurrence of parasitemia resulted from reinfection rather than resistance. Macro in vitro tests were done on an additional 67 infected persons, 11 of whom also had sensitive 7-day in vivo tests. Chloroquine resistance was not demonstrated in vitro. In Malindi 100% of isolates were inhibited by a chloroquine concentration of less than or equal to 0.75 nmol/ml blood and 80% by less than or equal to 0.5 nmol as compared with 69% and 27.3% respectively of those from Kisumu. These data from individuals living in malarious areas of Kenya contrast with continuing reports of proven chloroquine-resistant P. falciparum malaria in non-immune visitors who acquired their infections in Kenya.     

Molecular epidemiology of malaria in Yaounde, Cameroon V. analysis of the omega repetitive region of the plasmodium falciparum CG2 gene and chloroquine resistance

A novel Plasmodium falciparum gene, denoted cg2 gene, has been recently discovered, and a distinct genotype, characterized by 12 point mutations and 3 size polymorphisms, has been shown to be associated with chloroquine resistance in laboratory-adapted parasite strains. One of the polymorphic regions, denoted the omega region, consists of 16 tandem repeat units in chloroquine-resistant strains, while the chloroquine-sensitive strains have either < or = 15 or > or = 17 repeat units. In this study, the in vivo and in vitro responses were compared with the number of repeat units in the omega region of the cg2 gene for 75 Cameroonian isolates determined either by DNA sequencing or agarose gel electrophoresis. The 16-repeat units that characterize the resistant strains were found in 10 chloroquine-sensitive isolates (50% inhibitory concentration [IC50] < 100 nM) and 30 chloroquine-resistant isolates (IC50 > or = 100 nM). Thirty-five isolates (28 chloroquine-sensitive isolates and 7 chloroquine-resistant isolates) displayed < or = 15 or > or = 17 repeat units. Of the 18 patients responding with treatment failure, 15 were infected with parasites carrying 16 repeat units. Twenty-eight patients (11 with isolates carrying 16 repeat units and 17 with isolates carrying < or = 15 or > or = 17 repeat units) showed an adequate clinical response. The sensitivity, specificity, and predictive value were 81% (83%), 74% (61%), and 75% (58%), respectively compared with in vitro (or in vivo) responses. Neither the level of IC50 nor the key P. falciparum multidrug resistance gene 1 (pfmdr 1) allele at position 86 was associated with the number of omega repeat units. Although in vitro and in vivo resistance to chloroquine was statistically associated with the presence of 16 repeat units in the omega region (P < 0.05), the number of omega repeat units did not adequately discriminate patients infected with chloroquine-resistant parasites from those infected with chloroquine-sensitive parasites. Further studies on the cg2 gene are needed to determine whether cg2 gene is a reliable genetic marker for chloroquine resistance.     

Chloroquine/doxycycline combination versus chloroquine alone, and doxycycline alone for the treatment of Plasmodium falciparum and Plasmodium vivax malaria in northeastern Irian Jaya, Indonesia.

Combination therapy is one method of overcoming the global challenge of drug-resistant Plasmodium falciparum malaria. We conducted a hospital-based 28-day in vivo test comparing chloroquine/doxycycline to chloroquine or doxycycline alone for treating P. falciparum and Plasmodium vivax malaria in Irian Jaya, Indonesia. Eighty-nine patients with uncomplicated falciparum malaria were randomized to standard dose chloroquine (n = 30), doxycycline (100 mg every 12 hours [7 days], n = 20), or chloroquine with doxycycline (n = 39); corresponding numbers for vivax malaria (n = 63) were 23, 16, 24. Endpoints were parasite sensitivity (S) or resistance (RI/RII/RIII). Of the 105 evaluable patients, chloroquine/doxycycline cured (S) 20/22 (90.9% [95% CI 78.9-100%]) patients with P. falciparum malaria; 2/22 (9.1% [0-21%]) were RIII resistant. Doxycycline cured 11/17 (64.7% [42.0-87.4%]) patients, and chloroquine 4/20 (20% [2.5-37.5%]). Against P. vivax, chloroquine/doxycycline cured (S) 12/17 (70.6% [48.9-92.2%]) patients, doxycycline 4/12 (33.3% [6.6-59.9%]), and chloroquine 5/17 (29.4% [7.7-51.1%]). Chloroquine/doxycycline was effective against P. falciparum but only modestly effective against P. vivax. These findings support the use of chloroquine/doxycycline as an inexpensive alternative to mefloquine for treating chloroquine-resistant P. falciparum but not chloroquine-resistant P. vivax in this setting.     

Chloroquine-resistant isolates of Plasmodium falciparum with alternative CG2 omega repeat length polymorphisms

A particular polymorphism in the cg2 gene has previously been linked to chloroquine resistance in reference isolates of Plasmodium falciparum. To assess the association of this polymorphism with chloroquine resistance in field specimens of P. falciparum, we analyzed the omega repeat region of the cg2 gene in 47 isolates of P. falciparum collected in the Ingwavuma District of northern KwaZulu-Natal, South Africa. Polymerase chain reaction (PCR) primers, which were designed to amplify the region of DNA surrounding the omega repeat, were used to obtain omega repeat PCR products from the field isolates. The PCR product for each isolate varied in length, depending on the number of cg2 omega repeats for that isolate. We found that several in vivo and in vitro chloroquine-resistant isolates of P. falciparum did not have the expected 16 omega repeats. These results suggest that the link between the cg2 polymorphism and chloroquine resistance identified previously may not apply in all malarious areas.