CCN1 mutation is associated with atrial septal defect.

The genetic basis of congenital heart disease remains unknown in most of the cases. Recently, a novel mouse model shed new light on the role of CCN1/CYR61, a matricellular regulatory factor, in cardiac morphogenesis. In a candidate gene approach, we analyzed a cohort of 143 patients with atrial septal defects (ASD) by sequencing the coding exons of CCN1. In addition to three frequent polymorphisms, we identified an extremely rare novel heterozygous missense mutation (c.139C > T; p.R47W) in one patient with severe ASD. The mutation leads to an exchange of residues with quite different properties in a highly conserved position of the N-terminal insulin-like growth factor binding protein module. Further bioinformatic analysis, exclusion of known ASD disease genes as well as the exclusion of the mutation in a very high number of ethnically matched controls (more than 1,000 individuals) and in public genetic databases, indicates that the p.R47W variant is a probable disease-associated mutation. The report about ASD in mice in heterozygous Ccn 1 +/- animals strongly supports this notion. Our study is the first to suggest a relationship between a probable CCN1 mutation and ASD. Our purpose here was to draw attention to CCN1, a gene that we believe may be important for genetic analysis in patients with congenital heart disease.

The amount and value of work time of community medicine distributors in community case management of malaria among children under five years in the Ejisu-Juaben District of Ghana.

BACKGROUND: The contribution of community medicine distributors (CMD) to prompt health service delivery in areas described as "hard-to-reach" is important but the value of their work time remains unknown and thus makes it difficult to design appropriate regular financial incentives to motivate them. This makes CMDs feel their efforts are not recognized. An attempt to estimate the value of 54 CMDs' work time involved in community case management of malaria (CCMm) in a rural district in Ghana is presented. METHODS: Time spent by CMDs on CCMm activities were recorded for a period of 12 months to determine the work-time value. Cost analysis was performed in Microsoft Excel with data from CMD records and at 2007 market price in Ghana. RESULTS: A CMD spent 4.8 hours, [95% CI: 3.9; 5.3] on all CCMm-related activities per day. The time value of CMD work ranged from GH¢ 2.04 (US$ 2.24) to GH¢ 4.1 [US$ 4.6] per week and GH¢ 19.2 - 86.4 (US$ 21.10-94.95) per month. The gross wage outside CCMm as reported by CMD was GH¢ 58.4 [US$ 64.69] and value of foregone income of GH¢ 86.40 (US$ 94.95) per month, about 14-times higher than the monthly incentives of GH¢ 6.0 given by the CCMm programme. CONCLUSION: The value of work time and the foregone income of CMDs in CCMm are high and yet there are no regular and sustainable incentives provided for them. The results are significant to policy in designing incentives to motivate CMDs in large-scale implementation of CCMm.

Feasibility and acceptability of ACT for the community case management of malaria in urban settings in five African sites.

BACKGROUND: The community case management of malaria (CCMm) is now an established route for distribution of artemisinin-based combination therapy (ACT) in rural areas, but the feasibility and acceptability of the approach through community medicine distributors (CMD) in urban areas has not been explored. It is estimated that in 15 years time 50% of the African population will live in urban areas and transmission of the malaria parasite occurs in these densely populated areas. METHODS: Pre- and post-implementation studies were conducted in five African cities: Ghana, Burkina Faso, Ethiopia and Malawi. CMDs were trained to educate caregivers, diagnose and treat malaria cases in < 5-year olds with ACT. Household surveys, focus group discussions and in-depth interviews were used to evaluate impact. RESULTS: Qualitative findings: In all sites, interviews revealed that caregivers' knowledge of malaria signs and symptoms improved after the intervention. Preference for CMDs as preferred providers for malaria increased in all sites.Quantitative findings: 9001 children with an episode of fever were treated by 199 CMDs in the five study sites. Results from the CHWs registers show that of these, 6974 were treated with an ACT and 6933 (99%) were prescribed the correct dose for their age. Fifty-four percent of the 3,025 children for which information about the promptness of treatment was available were treated within 24 hours from the onset of symptoms.From the household survey 3700 children were identified who had an episode of fever during the preceding two weeks. 1480 (40%) of them sought treatment from a CMD and 1213 of them (82%) had received an ACT. Of these, 1123 (92.6%) were administered the ACT for the correct number of doses and days; 773 of the 1118 (69.1%) children for which information about the promptness of treatment was available were treated within 24 hours from onset of symptoms, and 768 (68.7%) were treated promptly and correctly. CONCLUSIONS: The concept of CCMm in an urban environment was positive, and caregivers were generally satisfied with the services. Quality of services delivered by CMDs and adherence by caregivers are similar to those seen in rural CCMm settings. The proportion of cases seen by CMDs, however, tended to be lower than was generally seen in rural CCMm. Urban CCMm is feasible, but it struggles against other sources of established healthcare providers. Innovation is required by everyone to make it viable.

Susceptibility to tuberculosis is associated with TLR1 polymorphisms resulting in a lack of TLR1 cell surface expression.

Human TLR1 plays an important role in host defense against Mycobacterium tuberculosis. Our aim was to analyze the association of the loss of TLR1 surface expression and TLR1 SNPs with susceptibility to TB. TLR1neg and TLR1pos cells from healthy individuals were identified by flow cytometry and compared by sequencing. TLR1 expression was measured using quantitative real-time PCR and immunoblotting. TLR1 SNP analyses of healthy individuals and TB patients from EU-C and Ghana were performed, and association of the TLR1 genotypes with increased risk of developing TB was statistically evaluated. Lack of TLR1 surface expression accompanied by impaired function was strongly associated with TLR1 SNP G743A. Genotyping of EU-C controls and TB patients revealed an association of TLR1 743A/1805G alleles [OR 2.37 (95% CI 1.13, 4.93), P=0.0219; OR 2.74 (95% CI 1.26, 6.05), P=0.0059] as well as TLR1neg 743AA/1805GG versus TLR1pos genotypes 743AG/1805TG [OR 4.98 (95% CI 1.64, 15.15), P=0.0034; OR 5.70 (95% CI 1.69, 20.35), P=0.0015] and 743AG + GG/1805TG + TT [OR 3.54 (95% CI 1.29, 9.90), P=0.0086; OR 4.17 (95% CI 1.52, 11.67), P=0.0025] with increased susceptibility to TB. No association of G743A with TB was found in Ghana as a result of a low frequency of genotype 743AA. Our data gain new insights in the role of TLR1 in M. tuberculosis defense and provide the first evidence that TLR1 variants are associated with susceptibility to TB in a low-incidence country.

The new Powerplex® ESX17 and ESI17 kits in paternity and maternity analyses involving people from Africa--including allele frequencies for three African populations.

Paternity and maternity investigations in immigration procedures are frequently done in Germany. Since mostly only one parent and one or more children are investigated, the occurrence of possible mutational events has to be interpreted with great care and the analysis of as many STRs as possible is recommended. The new Powerplex® ESX17 and Powerplex® ESI17 kits from Promega comprising both eleven established STRs and additionally the loci D1S1656, D2S441, D10S1248, D12S391, and D22S1045 (in different order) are potential tools in such paternity or maternity analyses, but only few allele frequency data for the five new loci exist. Here, we provide allele frequencies for the five additional STRs from three different populations from Africa. In addition, we present two maternity cases and one paternity case in which a clear inclusion or exclusion of the alleged parent could only be achieved by the additional application of the new Powerplex® ESX17 kit.

Reporting on road traffic injury: content analysis of injuries and prevention opportunities in Ghanaian newspapers.

In order to analyse traffic injury reporting in Ghanaian newspapers and identify opportunities for improving road safety, the content of 240 articles on road traffic injury was reviewed from 2005 to 2006 editions of two state-owned and two privately owned newspapers. The articles comprised reports on vehicle crashes (37%), commentaries (33%), informational pieces (12%), reports on pedestrian injury (10%), and editorials (8%). There was little coverage of pedestrian injuries, which account for half of the traffic fatalities in Ghana, but only 22% of newspaper reports. Only two articles reported on seatbelt use. Reporting patterns were similar between public and private papers, but private papers more commonly recommended government action (50%) than did public papers (32%, p=0.006). It is concluded that Ghanaian papers provide detailed coverage of traffic injury. Areas for improvement include pedestrian injury and attention to preventable risk factors such as road risk factors, seatbelt use, speed control, and alcohol use.

Unequal distribution of resistance-conferring mutations among Mycobacterium tuberculosis and Mycobacterium africanum strains from Ghana.

Isoniazid (INH) and rifampicin (RMP) resistance in Mycobacterium tuberculosis complex (MTC) isolates are mainly based on mutations in a limited number of genes. However, mutation frequencies vary in different mycobacterial populations. In this work, we analyzed the distribution of resistance-associated mutations in M. tuberculosis and M. africanum strains from Ghana, West Africa. The distribution of mutations in katG, fabG1-inhA, ahpC, and rpoB was determined by DNA sequencing in 217 INH-resistant (INH(r)) and 45 multidrug-resistant (MDR) MTC strains isolated in Ghana from 2001 to 2004. A total of 247 out of 262 strains investigated (94.3%) carried a mutation in katG (72.5%), fabG1-inhA (25.1%), or ahpC (6.5%), respectively. M. tuberculosis strains mainly had katG 315 mutations (80.1%), whereas this proportion was significantly lower in M. africanum West-African 1 (WA1) strains (43.1%; p<0.05). In contrast, WA1 strains showed more mutations in the fabG1-inhA region (39.2%, p<0.05) compared to M. tuberculosis strains (20.9%). In 44 of 45 MDR strains (97.8%) mutations in the 81-bp core region of the rpoB gene could be verified. Additionally, DNA sequencing revealed that 5 RMP-susceptible strains also showed mutations in the rpoB hotspot region. In conclusion, although principally the same genes were affected in INH(r)M. tuberculosis and M. africanum strains, disequilibrium in the distribution of mutations conferring resistance was verified that might influence the efficiency of molecular tests for determination of resistance.

Autophagy gene variant IRGM -261T contributes to protection from tuberculosis caused by Mycobacterium tuberculosis but not by M. africanum strains.

The human immunity-related GTPase M (IRGM) has been shown to be critically involved in regulating autophagy as a means of disposing cytosolic cellular structures and of reducing the growth of intracellular pathogens in vitro. This includes Mycobacterium tuberculosis, which is in agreement with findings indicating that M. tuberculosis translocates from the phagolysosome into the cytosol of infected cells, where it becomes exposed to autophagy. To test whether IRGM plays a role in human infection, we studied IRGM gene variants in 2010 patients with pulmonary tuberculosis (TB) and 2346 unaffected controls. Mycobacterial clades were classified by spoligotyping, IS6110 fingerprinting and genotyping of the pks1/15 deletion. The IRGM genotype -261TT was negatively associated with TB caused by M. tuberculosis (OR 0.66, CI 0.52-0.84, P(nominal) 0.0009, P(corrected) 0.0045) and not with TB caused by M. africanum or M. bovis (OR 0.95, CI 0.70-1.30. P 0.8). Further stratification for mycobacterial clades revealed that the protective effect applied only to M. tuberculosis strains with a damaged pks1/15 gene which is characteristic for the Euro-American (EUAM) subgroup of M. tuberculosis (OR 0.63, CI 0.49-0.81, P(nominal) 0.0004, P(corrected) 0.0019). Our results, including those of luciferase reporter gene assays with the IRGM variants -261C and -261T, suggest a role for IRGM and autophagy in protection of humans against natural infection with M. tuberculosis EUAM clades. Moreover, they support in vitro findings indicating that TB lineages capable of producing a distinct mycobacterial phenolic glycolipid that occurs exclusively in strains with an intact pks1/15 gene inhibit innate immune responses in which IRGM contributes to the control of autophagy. Finally, they raise the possibility that the increased frequency of the IRGM -261TT genotype may have contributed to the establishment of M. africanum as a pathogen in the West African population.

CTLA4 autoimmunity-associated genotype contributes to severe pulmonary tuberculosis in an African population.

The gene of Cytotoxic T Lymphocyte-associated Antigen 4 (CTLA4), a negative regulator of T lymphocytes, contains a single-nucleotide polymorphism (SNP) at position +6230A->G (ct60A->G), which has been found associated with several autoimmune diseases and appears to reduce T-cell inhibitory activity. In Ghana, West Africa, we compared the frequencies of CTLA4 +6230 A/G and 6 haplotype-tagging SNPs in 2010 smear-positive, HIV-negative patients with pulmonary tuberculosis (TB) and 2346 controls matched for age, gender and ethnicity. We found no difference in allele frequencies between cases and controls. However, +6230A and a distinct CTLA4 haplotype and a diplotype comprising the +6230A allele were significantly less frequent among cases with large opacities in chest radiographs compared to those with small ones (P(corrected [cor]) = 0.002, P(cor) = 0.00045, P = 0.0005, respectively). This finding suggests that an increased T-cell activity associated with the CTLA4 +6230G allele contributes to pathology rather than to protection in pulmonary TB.

IL10 haplotype associated with tuberculin skin test response but not with pulmonary TB.

Evidence from genetic association and twin studies indicates that susceptibility to tuberculosis (TB) is under genetic control. One gene implicated in susceptibility to TB is that encoding interleukin-10 (IL10). In a group of 2010 Ghanaian patients with pulmonary TB and 2346 healthy controls exposed to Mycobacterium tuberculosis, among them 129 individuals lacking a tuberculin skin test (PPD) response, we genotyped four IL10 promoter variants at positions -2849 , -1082 , -819 , and -592 and reconstructed the haplotypes. The IL10 low-producer haplotype -2849A/-1082A/-819C/-592C, compared to the high-producer haplotype -2849G/-1082G/-819C/-592C, occurred less frequent among PPD-negative controls than among cases (OR 2.15, CI 1.3-3.6) and PPD-positive controls (OR 2.09, CI 1.2-3.5). Lower IL-10 plasma levels in homozygous -2849A/-1082A/-819C/-592C carriers, compared to homozygous -2849G/-1082G/-819C/-592C carriers, were confirmed by a IL-10 ELISA (p = 0.016). Although we did not observe differences between the TB patients and all controls, our results provide evidence that a group of individuals exposed to M. tuberculosis transmission is genetically distinct from healthy PPD positives and TB cases. In these PPD-negative individuals, higher IL-10 production appears to reflect IL-10-dependent suppression of adaptive immune responses and sustained long-term specific anergy.

MCP-1 promoter variant -362C associated with protection from pulmonary tuberculosis in Ghana, West Africa.

Current endeavour focuses on human genetic factors that contribute to susceptibility to or protection from tuberculosis (TB). Monocytes are crucial in containing Mycobacterium tuberculosis infection, and the monocyte chemoattractant protein-1 (MCP-1) cytokine plays a role in their recruitment to the site of infection. The G allele of the MCP-1 promoter polymorphism at position -2581 relative to the ATG transcription start codon has been described to be associated in Mexican and Korean TB patients with increased susceptibility to TB. We genotyped this and additional MCP-1 variants in sample collections comprising more than 2000 cases with pulmonary TB and more than 2300 healthy controls and 332 affected nuclear families from Ghana, West Africa, and more than 1400 TB patients and more than 1500 controls from Russia. In striking contrast to previous reports, MCP-1 -2581G was significantly associated with resistance to TB in cases versus controls [odds ratio (OR) 0.81, corrected P-value (P(corr)) = 0.0012] and nuclear families (OR 0.72, P(corr) = 0.04) and not with disease susceptibility, whereas in the Russian sample no evidence of association was found (P = 0.86). Our and other results do not support an association of MCP-1 -2581 with TB. In the Ghanaian population, eight additional MCP-1 polymorphisms were genotyped. MCP-1 -362C was associated with resistance to TB in the case-control collection (OR 0.83, P(corr) = 0.00017) and in the affected families (OR 0.7, P(corr) = 0.004). Linkage disequilibrium (LD) and logistic regression analyses indicate that, in Ghanaians, the effect results exclusively from the MCP-1 -362 variant, whereas the effect of -2581 may in part be explained by its LD with -362.

Allele frequencies of 11 X-chromosomal loci in a population sample from Ghana.

Eleven X-chromosomal short tandem repeats (STRs) from two multiplex PCR approaches (DXS6807, DXS8378, DXS7132, DXS6800, DXS9898, DXS7424, DXS101, DXS7133, HPRTB, DXS8377, and DXS7423), located in four different X-chromosomal linkage groups, were typed in a population sample from Ghana, Africa. After genotyping unrelated men (129) and women (114) from the Ashanti population, forensic efficiency parameters such as polymorphism information content and mean exclusion chance were calculated. A deviation from the Hardy-Weinberg equilibrium could not be found. The investigation of 11 father-daughter and seven mother-son meioses revealed no mutations in any STR analyzed. Our data were compared with European, African-American, and Asian populations from the literature.

Effectiveness of artemisinin-based combination therapy used in the context of home management of malaria: a report from three study sites in sub-Saharan Africa.

BACKGROUND: The use of artemisinin-based combination therapy (ACT) at the community level has been advocated as a means to increase access to effective antimalarial medicines by high risk groups living in underserved areas, mainly in sub-Saharan Africa. This strategy has been shown to be feasible and acceptable to the community. However, the parasitological effectiveness of ACT when dispensed by community medicine distributors (CMDs) within the context of home management of malaria (HMM) and used unsupervised by caregivers at home has not been evaluated. METHODS: In a sub-set of villages participating in a large-scale study on feasibility and acceptability of ACT use in areas of high malaria transmission in Ghana, Nigeria and Uganda, thick blood smears and blood spotted filter paper were prepared from finger prick blood samples collected from febrile children between six and 59 months of age reporting to trained CMDs for microscopy and PCR analysis. Presumptive antimalarial treatment with ACT (artesunate-amodiaquine in Ghana, artemether-lumefantrine in Nigeria and Uganda) was then initiated. Repeat finger prick blood samples were obtained 28 days later for children who were parasitaemic at baseline. For children who were parasitaemic at follow-up, PCR analyses were undertaken to distinguish recrudescence from re-infection. The extent to which ACTs had been correctly administered was assessed through separate household interviews with caregivers having had a child with fever in the previous two weeks. RESULTS: Over a period of 12 months, a total of 1,740 children presenting with fever were enrolled across the study sites. Patent parasitaemia at baseline was present in 1,189 children (68.3%) and varied from 60.1% in Uganda to 71.1% in Ghana. A total of 606 children (51% of infected children) reported for a repeat test 28 days after treatment. The crude parasitological failure rate varied from 3.7% in Uganda (C.I. 1.2%-6.2%) to 41.8% in Nigeria (C.I. 35%-49%). The PCR adjusted parasitological cure rate was greater than 90% in all sites, varying from 90.9% in Nigeria (C.I. 86%-95%) to 97.2% in Uganda (C.I. 95%-99%). Reported adherence to correct treatment in terms of dose and duration varied from 81% in Uganda (C.I. 67%-95%) to 97% in Ghana (C.I. 95%-99%) with an average of 94% (C.I. 91%-97%). CONCLUSION: While follow-up rates were low, this study provides encouraging data on parasitological outcomes of children treated with ACT in the context of HMM and adds to the evidence base for HMM as a public health strategy as well as for scaling-up implementation of HMM with ACTs.

Pulmonary tuberculosis: virulence of Mycobacterium africanum and relevance in HIV co-infection.

Although Mycobacterium africanum is being isolated in a significant proportion of cases of pulmonary tuberculosis in West Africa, its pathogenic potential remains a matter of discussion. Recent reports leave the question of whether M. africanum causes more severe pathology than M. tuberculosis or resembles opportunistic pathogens and might gain importance in the course of the HIV pandemic. Patients with pulmonary tuberculosis associated with M. africanum (n=556) and M. tuberculosis (n=1350) were studied in Ghana, West Africa, and compared regarding self-reported signs and symptoms, chest radiography, HIV status, mycobacterial drug resistance and mycobacterial clustering as determined by spoligotyping and IS6110 fingerprints. The rate of M. africanum infections was similar in HIV-positive (27%) and HIV-negative (30%) patients. M. africanum clustered less than M. tuberculosis (21% vs 79%; OR, 0.38; 95% CI, 0.3-0.5; p<0.001) corresponding to its lower prevalence (29% vs 70%). Clinically and radiographically, no significant differences were found except that M. africanum caused lower-lobe disease less frequently than M. tuberculosis (OR, 0.39; 95% CI, 0.2-0.7; Pc=0.01), whereby this association applied to HIV-negative patients only. No difference in virulence, as assessed by the severity of radiological presentation, was found when the two M. africanum subtypes West African 1 and West African 2 were compared. In the population studied, M. africanum closely resembled M. tuberculosis in pathology and cannot be considered an opportunistic pathogen.

Feasibility and acceptability of artemisinin-based combination therapy for the home management of malaria in four African sites.

BACKGROUND: The Home Management of Malaria (HMM) strategy was developed using chloroquine, a now obsolete drug, which has been replaced by artemisinin-based combination therapy (ACT) in health facility settings. Incorporation of ACT in HMM would greatly expand access to effective antimalarial therapy by the populations living in underserved areas in malaria endemic countries. The feasibility and acceptability of incorporating ACT in HMM needs to be evaluated. METHODS: A multi-country study was performed in four district-size sites in Ghana (two sites), Nigeria and Uganda, with populations ranging between 38,000 and 60,000. Community medicine distributors (CMDs) were trained in each village to dispense pre-packaged ACT to febrile children aged 6-59 months, after exclusion of danger signs. A community mobilization campaign accompanied the programme. Artesunate-amodiaquine (AA) was used in Ghana and artemether-lumefantrine (AL) in Nigeria and Uganda. Harmonized qualitative and quantitative data collection methods were used to evaluate CMD performance, caregiver adherence and treatment coverage of febrile children with ACTs obtained from CMDs. RESULTS: Some 20,000 fever episodes in young children were treated with ACT by CMDs across the four study sites. Cross-sectional surveys identified 2,190 children with fever in the two preceding weeks, of whom 1,289 (59%) were reported to have received ACT from a CMD. Coverage varied from 52% in Nigeria to 75% in Ho District, Ghana. Coverage rates did not appear to vary greatly with the age of the child or with the educational level of the caregiver. A very high proportion of children were reported to have received the first dose on the day of onset or the next day in all four sites (range 86-97%, average 90%). The proportion of children correctly treated in terms of dose and duration was also high (range 74-97%, average 85%). Overall, the proportion of febrile children who received prompt treatment and the correct dose for the assigned duration of treatment ranged from 71% to 87% (average 77%). Almost all caregivers perceived ACT to be effective, and no severe adverse events were reported. CONCLUSION: ACTs can be successfully integrated into the HMM strategy.

ALOX5 variants associated with susceptibility to human pulmonary tuberculosis.

The 5-lipoxygenase (ALOX5)-derived lipid mediators leukotrienes and lipoxins have regulatory functions in inflammation by modulating activities of immune cells and cytokine production. Recently, it was shown in ALOX5-/- mice that host control of Mycobacterium tuberculosis is regulated by 5-lipoxygenase (5-LO). ALOX5 polymorphisms were genotyped in 1916 sputum-positive patients with pulmonary tuberculosis (TB) from Ghana and in 2269 exposed, apparently healthy controls. Polymorphisms of a variable number of tandem repeats (VNTR) of the ALOX5 promoter and of the exonic non-synonymous variant g.760G>A were analysed by fragment length determination and fluorescence resonance energy transfer, respectively, and DNA sequencing. Mycobacterial lineages of >1400 isolates were differentiated biochemically and genetically. Carriers of one variant (n repeats not equal 5) and one wild-type VNTR allele (n = 5) or of the exonic allele g.760A had a higher risk of TB [P(corrected) = 0.026, odds ratio (OR) 1.19 (95% CI 1.04-1.37) and P(corrected) = 0.026, OR 1.21 (95% CI 1.04-1.41), respectively]. The association of the exonic variant was stronger in infections caused by the mycobacterial lineage M. africanum West-African 2 [P(corrected) = 0.024, OR 1.70; (95% CI 1.2-2.6)]. Determination of haplotypes revealed the strongest associaton with TB for the 'non-5/760A' haplotype compared with the 'non-5/760G' haplotype (P = 0.003, OR 1.50). Our observation of an association of ALOX5 variants with susceptibility to TB contributes evidence of the importance of 5-LO products to the regulation of immune responses to M. tuberculosis.

Genome-wide linkage analysis of malaria infection intensity and mild disease.

Although balancing selection with the sickle-cell trait and other red blood cell disorders has emphasized the interaction between malaria and human genetics, no systematic approach has so far been undertaken towards a comprehensive search for human genome variants influencing malaria. By screening 2,551 families in rural Ghana, West Africa, 108 nuclear families were identified who were exposed to hyperendemic malaria transmission and were homozygous wild-type for the established malaria resistance factors of hemoglobin (Hb)S, HbC, alpha(+) thalassemia, and glucose-6-phosphate-dehydrogenase deficiency. Of these families, 392 siblings aged 0.5-11 y were characterized for malaria susceptibility by closely monitoring parasite counts, malaria fever episodes, and anemia over 8 mo. An autosome-wide linkage analysis based on 10,000 single-nucleotide polymorphisms was conducted in 68 selected families including 241 siblings forming 330 sib pairs. Several regions were identified which showed evidence for linkage to the parasitological and clinical phenotypes studied, among them a prominent signal on Chromosome 10p15 obtained with malaria fever episodes (asymptotic z score = 4.37, empirical p-value = 4.0 x 10(-5), locus-specific heritability of 37.7%; 95% confidence interval, 15.7%-59.7%). The identification of genetic variants underlying the linkage signals may reveal as yet unrecognized pathways influencing human resistance to malaria.

High prevalence of markers for sulfadoxine and pyrimethamine resistance in Plasmodium falciparum in the absence of drug pressure in the Ashanti region of Ghana.

Markers of Plasmodium falciparum resistance to chloroquine (CQ) and pyrimethamine-sulfadoxine (PYR-SDX) are widespread in areas where malaria is endemic. In an area where the use PYR-SDX is negligible, the Ashanti Region of Ghana, West Africa, adult individuals were enrolled in an analysis of CQ- and PYR-SDX-associated molecular resistance markers in 2001 (n = 177) and 2003 (n = 180). Parasite prevalence, as assessed by PCR assays, were 56.5 and 48.8% in 2001 and 2003, respectively. A high frequency of CQ, PYR, and SDX resistance markers was observed, whereby, as a weak trend, the frequency was higher in 2003. The quintuple combination of three pfdhfr mutations and two pfdhps mutations has previously been recognized to be the most important determinant of PYR-SDX resistance. Approximately 60% of parasite carriers harbored fourfold mutated parasites, indicative of a considerable risk for a switch to high-level PYR-SDX resistance in an area where the rate of PYR-SDX use is low. Among the factors contributing to the high frequency of PYR-SDX resistance-associated mutations are background use of PYR-SDX, past use of PYR for malaria prophylaxis, cross-resistance of trimethoprim with PYR, and the sufficient biological fitness of resistant parasites in the absence of drug pressure.

Expression of variant surface antigens by Plasmodium falciparum parasites in the peripheral blood of clinically immune pregnant women indicates ongoing placental infection.

Placenta-sequestered Plasmodium falciparum parasites that cause pregnancy-associated malaria (PAM) in otherwise clinically immune women express distinct variant surface antigens (VSA(PAM)) not expressed by parasites in nonpregnant individuals. We report here that parasites from the peripheral blood of clinically immune pregnant women also express VSA(PAM), making them a convenient source of VSA(PAM) expressors for PAM vaccine research.