McGready, R., How a refugee community deals with adoption. British Medical Journal, 2003. 326: p. 873.

Pattanasin, S., S. Proux, D. Chompasuk, K. Luwiradaj, P. Jacquier, L. S, and F. Nosten, Evaluation of a new Plasmodium lactate dehydrogenase assay (OptiMAL-IT) for the detection of malaria. Transactions of the Royal Society of Tropical Medicine and Hygiene, 2003. 97.

Nosten, F., R. McGready, S. Looareesuwan, and N. White, Editorial: Maternal malaria: time for action. Tropical Medicine and International Health, 2003. 8(6): p. 485-487.Pubmed

Chaorattanakawee, S., O. Natalang, H. Hananantachai, M. Nacher, A. Brockman, F. Nosten, S. Looareesuwan, and J. Patarapotikul, Trichuris trichiura infection is associated with the multiplicity of Plasmodium falciparum infections, in Thailand. Annals of Tropical Medicine and Parasitology, 2003. 97(2): p. 199-202.Pubmed

Nair, S., J.T. Williams, A. Brockman, L. Paiphun, M. Mayxay, P.N. Newton, J.P. Guthmann, F.M. Smithuis, T.T. Hien, N.J. White, F. Nosten, and T.J. Anderson, A selective sweep driven by pyrimethamine treatment in southeast asian malaria parasites. Molecular Biology and Evolution, 2003. 20(9): p. 1526-36.Pubmed
Malaria parasites (Plasmodium falciparum) provide an excellent system in which to study the genomic effects of strong selection in a recombining eukaryote because the rapid spread of resistance to multiple drugs during the last the past 50 years has been well documented, the full genome sequence and a microsatellite map are now available, and haplotype data can be easily generated. We examined microsatellite variation around the dihydrofolate reductase (dhfr) gene on chromosome 4 of P. falciparum. Point mutations in dhfr are known to be responsible for resistance to the antimalarial drug pyrimethamine, and resistance to this drug has spread rapidly in Southeast (SE) Asia after its introduction in 1970s. We genotyped 33 microsatellite markers distributed across chromosome 4 in 61 parasites from a location on the Thailand/Myanmar border. We observed minimal microsatellite length variation in a 12-kb (0.7-cM) region flanking the dhfr gene and diminished variation for approximately 100 kb (6 cM), indicative of a single origin of resistant alleles. Furthermore, we found the same or similar microsatellite haplotypes flanked resistant dhfr alleles sampled from 11 parasite populations in five SE Asian countries indicating recent invasion of a single lineage of resistant dhfr alleles in locations 2,000 km apart. Three features of these data are of especial interest. (1) Pyrimethamine resistance is generally assumed to have evolved multiple times because the genetic basis is simple and resistance can be selected easily in the laboratory. Yet our data clearly indicate a single origin of resistant dhfr alleles sampled over a large region of SE Asia. (2) The wide valley ( approximately 6 cM) of reduced variation around dhfr provides "proof-of-principle" that genome-wide association may be an effective way to locate genes under strong recent selection. (3) The width of the selective valley is consistent with predictions based on independent measures of recombination, mutation, and selection intensity, suggesting that we have reasonable estimates of these parameters. We conclude that scanning the malaria parasite genome for evidence of recent selection may prove an extremely effective way to locate genes underlying recently evolved traits such as drug resistance, as well as providing an opportunity to study the dynamics of selective events that have occurred recently or are currently in progress.

Chaorattanakawee, S., O. Natalang, H. Hananantachai, M. Nacher, A. Brockman, S. Krudsood, S. Looareesuwan, and J. Patarapotikul, Storage duration and polymerase chain reaction detection of Plasmodium falciparum from blood spots on filter paper. Am J Trop Med Hyg, 2003. 69(1): p. 42-4.Pubmed
To evaluate the effect of long-term storage of sample filters on the sensitivity of polymerase chain reaction (PCR) detection of malaria, 252 blood spots from patients with microscopically confirmed Plasmodium falciparum malaria were analyzed and stratified by storage duration. The spots were collected between 1996 and 2000 on filter paper and stored at room temperature. A Chelex-based method was used to extract the DNA. Unexpectedly, after the first purification, the sensitivity of the PCR from recently stored samples was low and showed progressively increased with time storage (P = 0.003, by chi-square test for linear trend). This suggested that PCR inhibitors were easier to dissolve from the more recent blood spots (< 4 years old) than from blood spots > or = 4 years old, thus leading to a time-dependent increase in PCR sensitivity. However, if DNA was purified again (when the first PCR result was negative), the cumulative sensitivity was not influenced by storage duration. This indicated that length of storage is not a critical issue providing purification is sufficient.

McGready, R., K. Stepniewska, E. Seaton, T. Cho, D. Cho, A. Ginsberg, M.D. Edstein, E. Ashley, S. Looareesuwan, N.J. White, and F. Nosten, Pregnancy and use of oral contraceptives reduces the biotransformation of proguanil to cycloguanil. European Journal of Clinical Pharmacology, 2003. 59(7): p. 553-557.Pubmed
OBJECTIVE. To determine the effects of late pregnancy and also oestrogen supplementation on the CYP2C19-mediated biotransformation of proguanil (PG) to its active antifol triazine metabolite cycloguanil (CG). METHODS. Case control study conducted on the NW border of Thailand; a single dose of PG (4 mg/kg) was administered to Karen women in late pregnancy and a single blood and urine sample taken 6 h later. Women were studied in late pregnancy (>36 weeks) and restudied 2 months after delivery. A separate cohort of Karen women newly attending a birth-control clinic were studied before and 3 weeks into their first course of oral contraceptives (OCP: levonorgestrel 0.15 mg and ethinyloestradiol 0.03 mg). Forty-five pregnant women and forty-two healthy OCP users were studied. RESULTS. The results were similar in both groups; pregnancy and OCP use were both associated with reduced formation of cycloguanil (CG). Impaired PG biotransformation was seen in women with the "extensive metaboliser" phenotype (urine PG/CG ratio <10). CG levels, adjusted for dose, were a median (range) 73% (-59 to 420%) higher following the pregnancy than during the pregnancy in women characterised as extensive metabolisers ( P<0.001). CG levels in women characterised as extensive metabolisers were 34% (-54 to 323%) higher before than while taking the OCP ( P<0.01). CONCLUSION. Late pregnancy and OCP use impair biotransformation of the active antimalarial metabolite CG from the parent PG. This may be mediated by oestrogen inhibition of CYP2C19 activity. The dose of PG should be increased by 50% in these groups.

McGready, R., K. Stepniewska, M.D. Edstein, T. Cho, G. Gilveray, S. Looareesuwan, N.J. White, and F. Nosten, The pharmacokinetics of atovaquone and proguanil in pregnant women with acute falciparum malaria. European Journal of Clinical Pharmacology, 2003. 59(7): p. 545-552.Pubmed
OBJECTIVE. To determine the pharmacokinetic properties of atovaquone, proguanil, and the triazine metabolite cycloguanil in women with recrudescent multi-drug resistant falciparum malaria during the second and third trimesters of pregnancy treated by artesunate-atovaquone-proguanil. METHODS. Serial plasma concentrations of atovaquone, proguanil and cycloguanil were measured in 24 women at baseline and after the final dose of the 3-day treatment with atovaquone (20 mg/kg/day) plus proguanil (8 mg/kg/day) plus artesunate (4 mg/kg/day) daily. RESULTS. The triple combination was well tolerated and highly effective. The outcomes of pregnancy were all normal. Population mean (+/- SEM) oral clearance (Cl/F) estimates were 313+/-33 ml/h/kg and 1109+/-43 ml/h/kg, total apparent volume of distribution (Vd/F) 13.0+/-1.3 l/kg and 22.9+/-1.4 l/kg, and terminal elimination half-life; 29.1 h and 14.3 h, for atovaquone and proguanil, respectively. Using conventional and population pharmacokinetic analyses, Cl/F and Vd/F estimates for both drugs were approximately twice, and plasma concentrations less than half those reported previously in healthy subjects and patients with acute malaria. CONCLUSION. Artesunate-atovaquone-proguanil is a promising treatment for multi-drug resistant falciparum malaria during pregnancy, but the dose of atovaquone-proguanil may need to be increased.

Mayxay, M., P.N. Newton, M. Khanthavong, P. Tiengkham, R. Phetsouvanh, S. Phompida, A. Brockman, and N.J. White, Chloroquine versus Sulfadoxine-Pyrimethamine for Treatment of Plasmodium falciparum Malaria in Savannakhet Province, Lao People's Democratic Republic: An Assessment of National Antimalarial Drug Recommendations. Clin Infect Dis, 2003. 37(8): p. 1021-8.Pubmed
The in vivo efficacies of the Lao People's Democratic Republic (Laos) nationally recommended antimalarial agents-chloroquine and sulfadoxine-pyrimethamine-were assessed in a randomized, comparative trial that involved 100 patients with uncomplicated Plasmodium falciparum malaria who were followed for 42 days after starting treatment. Despite a shorter mean time to fever clearance associated with administration of chloroquine (mean time to clearance, 35.6 h; 95% confidence interval [CI], 26.3-45.0 h), compared with that associated with sulfadoxine-pyrimethamine (61.1 h; 95% CI, 50.9-71.3 h; P<.001), treatment failures were twice as frequent among patients receiving chloroquine therapy than among those receiving sulfadoxine-pyrimethamine therapy (36% vs. 18%; P=.02). Of 23 treatment failures, 10 (43%) were high grade. Treatment failure rates among children (age range, 5-15 years) were 4.9 times higher (95% CI, 2-12) than those among adults (P<.0001). Gametocytemia after antimalarial treatment was associated with receipt of sulfadoxine-pyrimethamine therapy and with treatment failure (P=.009). The efficacy of both chloroquine and sulfadoxine-pyrimethamine in Laos is unsatisfactory.

Nosten, F. and R. McGready, Burden of malaria during pregnancy in areas of stable and unstable transmission in Ethiopia during a nonepidemic year. Journal of Infectious Diseases, 2003. 188(8): p. 1259-61; author reply 1561-2.Pubmed

McGready, R., J.A. Simpson, R. Arunjerdja, I. Golfetto, K. Ghebremeskel, A. Taylor, A. Siemieniuk, E. Mercuri, G. Harper, L. Dubowitz, M. Crawford, and F. Nosten, Delayed visual maturation in Karen refugee infants. Annals of Tropical Paediatrics, 2003. 23(3): p. 193-204.Pubmed
Thirty-eight babies born to Karen mothers living in camps for displaced persons in north-western Thailand have delayed visual maturation (DVM type 1) that recovers within 6 months. Vitamin A concentrations were deficient in 16% of breast-milk samples from lactating mothers and vitamin B(1) concentrations were deficient in 60% of plasma samples. Infantile beriberi was common in this population. The levels of fatty acids in plasma and milk in Karen women were excellent at birth and in the postpartum period. The degree of deficiencies in these vitamins and the concentration of essential fatty acids in cord blood and maternal breast-milk did not correlate significantly with visual impairment in the infants. DVM might be caused by nutritional deficiency or toxic effects during critical periods of gestation that lead to delayed cortical myelination or structural defects which impinge on parietal cortex function.

Luxemburger, C., N.J. White, F. ter Kuile, H.M. Singh, I. Allier-Frachon, M. Ohn, T. Chongsuphajaisiddhi, and F. Nosten, Beri-beri: the major cause of infant mortality in Karen refugees. Transactions of the Royal Society of Tropical Medicine and Hygiene, 2003. 97(2): p. 251-5.Pubmed
During a prospective evaluation of malaria prophylaxis in pregnancy in a refugee population on the north-western border of Thailand from 1987 to 1990, an extremely high infant mortality rate (18%) was documented despite good access to health care. Infantile beri-beri was recognized as the main cause of death accounting for 40% of all infant mortality. Thereafter, severe vitamin B1 deficiency in infants was diagnosed and treated promptly. The impact of this was assessed prospectively from 1993 to 1996 in a second cohort study. The case fatality of infantile beri-beri fell from almost 100% to 7%. The overall infant mortality rates declined from 183 to 78 per 1000 live births. Post-neonatal deaths fell by 79% (95% CI 65-87%) while neonatal mortality remained unchanged. Mortality resulting from acute respiratory infections did not change (15 and 11 per 1000, respectively), whereas mortality attributable to beri-beri decreased from 73 to 5 per 1000 (P < 0.0001). Before its recognition approximately 7% of all infants in this population died from infantile beri-beri. This lethal but preventable syndrome may be more common than hitherto recognized, particularly in refugee populations, in this populous region.

Nacher, M., R. McGready, K. Stepniewska, T. Cho, S. Looareesuwan, N.J. White, and F. Nosten, Haematinic treatment of anaemia increases the risk of Plasmodium vivax malaria in pregnancy. Trans R Soc Trop Med Hyg, 2003. 97(3): p. 273-6.Pubmed
Nutritional deficiency and malaria are 2 major causes of anaemia during pregnancy in tropical areas. The relationship between anaemia, its treatment with iron and folate, and malaria was studied in a prospective cohort of 2112 pregnant Karen women on the north-western border of Thailand between 1993 and 1997. The development of Plasmodium vivax malaria was associated with a past mean haematocrit > 30% (hazard ratio = 1.5, 95% CI 1.2-2, P = 0.001) and recent (< or = 30 d) iron and folate supplementation (hazard ratio = 1.7, 95% CI 1.1-2.6, P = 0.01). There were no associations with P. falciparum infections. Plasmodium vivax has a predilection for young erythrocytes, and these results suggest that pregnant women with larger numbers of circulating young red cells are at greater risk of developing P. vivax malaria. In P. vivax-endemic areas, systematic iron and folate supplementation confers both benefit and risk in pregnancy.

Mayxay, M., R. Phetsouvanh, S. Phompida, P.N. Newton, M. Khanthavong, B. Vannachone, A. Brockman, and N.J. White, A randomized comparison of oral chloroquine and sulfadoxine-pyrimethamine for the treatment of uncomplicated Plasmodium falciparum malaria in Laos. Trans R Soc Trop Med Hyg, 2003. 97(3): p. 343-4.Pubmed
Between June and October 2000 we conducted the first randomized trial in Laos comparing chloroquine (CQ) with sulfadoxine-pyrimethamine (SP) in the treatment of uncomplicated Plasmodium falciparum malaria (n = 29, 42-d follow-up, age > 5 years). The proportion of patients with treatment failure was high (CQ = 78%, RIII 46%; SP = 36%, RIII 15%). The treatment policy for uncomplicated P. falciparum malaria in Laos needs to be reviewed urgently.

McGready, R., N.K. Keo, L. Villegas, N.J. White, S. Looareesuwan, and F. Nosten, Artesunate-atovaquone-proguanil rescue treatment of multidrug-resistant Plasmodium falciparum malaria in pregnancy: a preliminary report. Trans R Soc Trop Med Hyg, 2003. 97(5): p. 592-4.Pubmed
Pregnant women are particularly vulnerable to malaria infections. Multidrug resistance in Plasmodium falciparum seriously compromises treatment in some endemic areas. Between April 1999 and October 2001, we treated and prospectively followed 27 Karen pregnant women with multiple recrudescent P. falciparum infections who were resistant to all other antimalarials with a triple combination of artesunate-atovaquone-proguanil. The treatment was well tolerated and we found no evidence of toxicity for the mothers and the fetus. All but 1 woman were cured (cure rate 96%, 95% CI 89-100). The triple combination of artesunate (4 mg/kg/d), atovaquone (20 mg/kg/d), and proguanil (8 mg/kg/d) may provide a much needed, albeit expensive, 3-d rescue treatment for pregnant women exposed to multidrug- resistant P. falciparum malaria.