Publications (80)517.57 Total impact
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Article: Epidemiology of malaria in the forest-savanna transitional zone of Ghana.
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ABSTRACT: Information on the epidemiology of malaria is essential for designing and interpreting results of clinical trials of drugs, vaccines and other interventions. As a background to the establishment of a site for anti-malarial drugs and vaccine trials, the epidemiology of malaria in a rural site in central Ghana was investigated. Active surveillance of clinical malaria was carried out in a cohort of children below five years of age (n = 335) and the prevalence of malaria was estimated in a cohort of subjects of all ages (n = 1484) over a 12-month period. Participants were sampled from clusters drawn around sixteen index houses randomly selected from a total of about 22,000 houses within the study area. The child cohort was visited thrice weekly to screen for any illness and a blood slide was taken if a child had a history of fever or a temperature greater than or equal to 37.5 degree Celsius. The all-age cohort was screened for malaria once every eight weeks over a 12-month period. Estimation of Entomological Inoculation Rate (EIR) and characterization of Anopheline malaria vectors in the study area were also carried out. The average parasite prevalence in the all age cohort was 58% (95% CI: 56.9, 59.4). In children below five years of age, the average prevalence was 64% (95% CI: 61.9, 66.0). Geometric mean parasite densities decreased significantly with increasing age. More than 50% of all children less than 10 years of age were anaemic. Children less than 5 years of age had as many as seven malaria attacks per child per year. The attack rates decreased significantly with increasing cut-offs of parasite density. The average Multiplicity of Infection (MOI) was of 6.1. All three pyrimethamine resistance mutant alleles of the Plasmodium falciparum dhfr gene were prevalent in this population and 25% of infections had a fourth mutant of pfdhps-A437G. The main vectors were Anopheles funestus and Anopheles gambiae and the EIR was 269 infective bites per person per year. The transmission of malaria in the forest-savanna region of central Ghana is high and perennial and this is an appropriate site for conducting clinical trials of anti-malarial drugs and vaccines.Malaria Journal 09/2009; 8:220. · 3.19 Impact Factor -
Article: Insecticide resistance profiles for malaria vectors in the Kassena-Nankana district of Ghana.
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ABSTRACT: Malaria is a major public health problem in Ghana. The current strategy of the National Malaria Control Programme is based on effective case management and the use of insecticide treated bed nets among vulnerable groups such as children under-five years of age and pregnant women. Resistance to pyrethroids by Anopheles gambiae s.l. and Anopheles funestus has been reported in several African countries including neighbouring Burkina Faso. Indoor resting Anopheles mosquitoes were collected. Blood-fed and gravid females were allowed to oviposit, eggs hatched and larvae reared to 1-3 days old adults and tested against permethrin 0.75%, deltamethrin 0.05%, cyfluthrin 0.15%, lambdacyhalothrin 0.1% and DDT 4%, based on WHO methodology. PCR analyses were carried out on a sub-sample of 192 of the An. gambiae for sibling species complex determination. Resistance to pyrethroids and DDT was determined by genotyping the knock-down resistance kdr gene mutations in the study area. A total of 9,749 1-3 days-old F1 female Anopheles mosquitoes were exposed to the insecticides. Among the pyrethroids, permethrin, 0.75% had the least knockdown effect, whilst cyfluthrin 0.15%, had the highest knock-down effect. Overall, no difference in susceptibility between An. gambiae 93.3% (95% CI: 92.5-94.1) and An. funestus 94.5% (95% CI: 93.7-95.3) was observed when exposed to the pyrethroids. Similarly, there was no difference in susceptibility between the two vector species (An. gambiae = 79.1% (95% CI: 76.6-81.8) and An. funestus = 83.5% (95% CI: 80.2-86.4) when exposed to DDT. Overall susceptibility to the insecticides was between 80% and 98%, suggesting that there is some level of resistance, except for cyfluthrin 0.15%. The kdr PCR assay however, did not reveal any kdr mutations. The analysis also revealed only the molecular M (Mopti) form. The findings in this study show that An. gambiae and An. funestus, the main malaria vector mosquitoes in the Kassena-Nankana district are susceptible to the insecticides being used in the treatment of bed nets in the malaria control programme. There is however, the need for continuous monitoring of the pyrethroids as the efficacy is not very high.Malaria Journal 05/2009; 8:81. · 3.19 Impact Factor -
Article: Multiple origins and regional dispersal of resistant dhps in African Plasmodium falciparum malaria.
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ABSTRACT: Although the molecular basis of resistance to a number of common antimalarial drugs is well known, a geographic description of the emergence and dispersal of resistance mutations across Africa has not been attempted. To that end we have characterised the evolutionary origins of antifolate resistance mutations in the dihydropteroate synthase (dhps) gene and mapped their contemporary distribution. We used microsatellite polymorphism flanking the dhps gene to determine which resistance alleles shared common ancestry and found five major lineages each of which had a unique geographical distribution. The extent to which allelic lineages were shared among 20 African Plasmodium falciparum populations revealed five major geographical groupings. Resistance lineages were common to all sites within these regions. The most marked differentiation was between east and west African P. falciparum, in which resistance alleles were not only of different ancestry but also carried different resistance mutations. Resistant dhps has emerged independently in multiple sites in Africa during the past 10-20 years. Our data show the molecular basis of resistance differs between east and west Africa, which is likely to translate into differing antifolate sensitivity. We have also demonstrated that the dispersal patterns of resistance lineages give unique insights into recent parasite migration patterns.PLoS Medicine 05/2009; 6(4):e1000055. · 16.27 Impact Factor -
Article: Chlorproguanil-dapsone-artesunate versus artemether-lumefantrine: a randomized, double-blind phase III trial in African children and adolescents with uncomplicated Plasmodium falciparum malaria.
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ABSTRACT: Chlorproguanil-dapsone-artesunate (CDA) was developed as an affordable, simple, fixed-dose artemisinin-based combination therapy for use in Africa. This trial was a randomized parallel-group, double-blind, double-dummy study to compare CDA and artemether-lumefantrine (AL) efficacy in uncomplicated Plasmodium falciparum malaria and further define the CDA safety profile, particularly its hematological safety in glucose-6-phosphate dehydrogenase (G6PD) -deficient patients. The trial was conducted at medical centers at 11 sites in five African countries between June 2006 and August 2007. 1372 patients (> or =1 to <15 years old, median age 3 years) with acute uncomplicated P. falciparum malaria were randomized (2:1) to receive CDA 2/2.5/4 mg/kg once daily for three days (N = 914) or six-doses of AL over three days (N = 458). Non-inferiority of CDA versus AL for efficacy was evaluated in the Day 28 per-protocol (PP) population using parasitological cure (polymerase chain reaction [PCR]-corrected). Cure rates were 94.1% (703/747) for CDA and 97.4% (369/379) for AL (treatment difference -3.3%, 95%CI -5.6, -0.9). CDA was non-inferior to AL, but there was simultaneous superiority of AL (upper 95%CI limit <0). Adequate clinical and parasitological response at Day 28 (uncorrected for reinfection) was 79% (604/765) with CDA and 83% (315/381) with AL. In patients with a G6PD-deficient genotype (94/603 [16%] hemizygous males, 22/598 [4%] homozygous females), CDA had the propensity to cause severe and clinically concerning hemoglobin decreases: the mean hemoglobin nadir was 75 g/L (95%CI 71, 79) at Day 7 versus 97 g/L (95%CI 91, 102) for AL. There were three deaths, unrelated to study medication (two with CDA, one with AL). Although parasitologically effective at Day 28, the hemolytic potential of CDA in G6PD-deficient patients makes it unsuitable for use in a public health setting in Africa. ClinicalTrials.Gov NCT00344006.PLoS ONE 01/2009; 4(8):e6682. · 4.09 Impact Factor -
Article: Randomized controlled trial of RTS,S/AS02D and RTS,S/AS01E malaria candidate vaccines given according to different schedules in Ghanaian children.
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ABSTRACT: The target delivery channel of RTS,S candidate malaria vaccines in malaria-endemic countries in Africa is the World Health Organisation Expanded Program on Immunization. As an Adjuvant System, age de-escalation and schedule selection step, this study assessed 3 schedules of RTS,S/AS01(E) and RTS,S/AS02(D) in infants and young children 5-17 months of age in Ghana. A Phase II, partially-blind randomized controlled study (blind to vaccine, not to schedule), of 19 months duration was conducted in two (2) centres in Ghana between August 2006 and May 2008. Subjects were allocated randomly (1:1:1:1:1:1) to one of six study groups at each study site, each defining which vaccine should be given and by which schedule (0,1-, 0,1,2- or 0,1,7-months). For the 0,1,2-month schedule participants received RTS,S/AS01(E) or rabies vaccine at one center and RTS,S/AS01(E) or RTS,S/AS02(D) at the other. For the other schedules at both study sites, they received RTS,S/AS01(E) or RTS,S/AS02(D). The primary outcome measure was the occurrence of serious adverse events until 10 months post dose 1. The number of serious adverse events reported across groups was balanced. One child had a simple febrile convulsion, which evolved favourably without sequelae, considered to be related to RTS,S/AS01(E) vaccination. Low grade reactions occurred slightly more frequently in recipients of RTS,S/AS than rabies vaccines; grade 3 reactions were infrequent. Less local reactogenicity occurred with RTS,S/AS01(E) than RTS,S/AS02(D). Both candidate vaccines were highly immunogenic for anti-circumsporozoite and anti-Hepatitis B Virus surface antigen antibodies. Recipients of RTS,S/AS01(E) compared to RTS,S/AS02(D) had higher peak anti-circumsporozoite antibody responses for all 3 schedules. Three dose schedules were more immunogenic than 2 dose schedules. Area under the curve analyses for anti-circumsporozoite antibodies were comparable between the 0,1,2- and 0,1,7-month RTS,S/AS01(E) schedules. Both candidate malaria vaccines were well tolerated. Anti-circumsporozoite responses were greater with RTS,S/AS01(E) than RTS,S/AS02(D) and when 3 rather than 2 doses were given. This study supports the selection of RTS,S/AS01(E) and a 3 dose schedule for further development in children and infants. ClinicalTrials.gov NCT00360230.PLoS ONE 01/2009; 4(10):e7302. · 4.09 Impact Factor -
Article: Adherence to Artesunate-Amodiaquine Therapy for Uncomplicated Malaria in Rural Ghana: A Randomised Trial of Supervised versus Unsupervised Drug Administration.
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ABSTRACT: Introduction. To enhance effective treatment, african nations including Ghana changed its malaria treatment policy from monotherapy to combination treatment with artesunate-amodiaquine (AS+AQ). The major challenge to its use in loose form is adherence. Objective. The objectives of this study were to investigate adherence and treatment outcome among patients treated with AS+AQ combination therapy for acute uncomplicated malaria. Methodology. The study was conducted in two rural districts located in the middle belt of Ghana using quantitative methods. Patients diagnosed with acute uncomplicated malaria as per the Ghana Ministry of Health malaria case definitions were randomly allocated to one of two groups. All patients in both groups were educated about the dose regimen of AS+AQ therapy and the need for adherence. Treatment with AS+AQ was supervised in one group while the other group was not supervised. Adherence was assessed by direct observation of the blister package of AS+AQ left on day 2. Results. 401 participants were randomized into the supervised (211) and unsupervised (190) groups. Compliance in both supervised (95.7%) and unsupervised (92.6%) groups were similar (P = .18). The commonest side-effects reported on day 2 among both groups were headaches, and body weakness. Parasite clearance by day 28 was >95% in both groups. Discussion/Conclusions. Administration of AS-AQ in both groups resulted in high levels of adherence to treatment regimen among adolescent and adult population in central Ghana. It appears that high level of adherence to AS-AQ is achievable through a rigorous education programme during routine clinic visits.Journal of Tropical Medicine 01/2009; 2009:529583. -
Article: Aetiology of stillbirths and neonatal deaths in rural Ghana: implications for health programming in developing countries.
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ABSTRACT: In developing countries many stillbirths and neonatal deaths occur at home and cause of death is not recorded by national health information systems. A community-level verbal autopsy tool was used to obtain data on the aetiology of stillbirths and neonatal deaths in rural Ghana. Objectives were to describe the timing and distribution of causes of stillbirths and neonatal deaths according to site of death (health facility or home). Data were collected from 1 January 2003 to 30 June 2004; 20,317 deliveries, 696 stillbirths and 623 neonatal deaths occurred over that time. Most deaths occurred in the antepartum period (28 weeks gestation to the onset of labour) (33.0%). However, the highest risk periods were during labour and delivery (intrapartum period) and the first day of life. Infections were a major cause of death in the antepartum (10.1%) and neonatal (40.3%) periods. The most important cause of intrapartum death was obstetric complications (59.3%). There were significantly fewer neonatal deaths resulting from birth asphyxia in the home than in the health facilities and more deaths from infection. Only 59 (20.7%) mothers of neonates who died at home reported that they sought care from an appropriate health care provider (doctor, nurse or health facility) during their baby's illness. The results from this study highlight the importance of studying community-level data in developing countries and the high risk of intrapartum stillbirths and infectious diseases in the rural African mother and neonate. Community-level interventions are urgently needed, especially interventions that reduce intrapartum deaths and infection rates in the mother and infant.Paediatric and Perinatal Epidemiology 10/2008; 22(5):430-7. · 2.31 Impact Factor -
Article: Vitamin A supplements are well tolerated with the pentavalent vaccine.
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ABSTRACT: The Expanded Programme on Immunisation provides an opportunity to deliver vitamin A supplements to young infants in order to improve their vitamin A status. However, concerns have been raised about the safety of administering high dose vitamin A supplements to infants less than 6 months of age in developing countries. A randomized controlled trial was carried out by the Kintampo Health Research Centre to assess the safety and immunogenicity of administering 15 mg retinol equivalent (RE)1 vitamin A alongside the pentavalent "diphtheria-polio-tetanus-Haemophilus influenzae b-hepatitis B vaccine" at 6, 10 and 14 weeks of age. All mothers received a post-partum supplement of 120 mg RE vitamin A as per national policy. Mothers of infants who had been vaccinated were visited 24 h after vaccination to assess the side effects of the vaccine. They were also interviewed about adverse events which may have occurred in the past 4 weeks since the child was vaccinated. There were significantly fewer reports of illnesses and fever in infants who had been given vitamin A compared to infants in the control group. The pentavalent vaccine was found to be tolerable when administered with vitamin A according to the WHO/EPI schedule for infant immunisation at 6, 10 and 14 weeks. There were few complaints made by the mothers of the children which were not thought to be related to giving vitamin A with the vaccines. There were six deaths in the trial, five in the intervention group and one in the control RR 4.65 (0.55-39.5), p = 0.12. Due to the high point estimate of 4.65, we wish to urge caution in administering high doses of vitamin A to young infants with the pentavalent vaccine at 6, 10 and 14 weeks of age.Vaccine 10/2008; 26(51):6608-13. · 3.77 Impact Factor -
Article: Diagnostic accuracy of verbal autopsies in ascertaining the causes of stillbirths and neonatal deaths in rural Ghana.
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ABSTRACT: This study evaluated the diagnostic accuracy of a verbal autopsy (VA) tool in ascertaining the causes of stillbirths and neonatal deaths in rural Ghana and was nested within a community-based maternal vitamin A supplementation trial (ObaapaVitA trial). All stillbirths and neonatal deaths between 1 January 2003 and 30 June 2004 were prospectively included. Community VAs were carried out within 6 months of death and were classified with a primary cause of death by three experienced paediatricans. The reference standard diagnosis was obtained by the study paediatrician in 4 district hospitals in the study area. There were 20,317 deliveries, 661 stillbirths and 590 neonatal deaths with a VA diagnosis in the study population. A total of 311 stillbirths and 191 neonatal deaths had both a VA and a hospital reference standard diagnosis. The VA performed poorly for stillbirth diagnoses such as congenital abnormalities and maternal haemorrhage. Accuracy was higher for intrapartum obstetric complications and antepartum maternal disease. For neonatal deaths, sensitivity was >60% for all major causes; specificity was 76% for birth asphyxia but >85% for prematurity and infection. Overall, VA diagnostic accuracy was higher than expected in this rural African setting. Our classification system was based on the expected public health importance of the individual causes of death, differing implications for intervention and the ability to distinguish between the individual causes in low-resource settings. We believe this system was easier to use than traditional approaches and resulted in high precision and accuracy. However, further simplifications are needed to allow use of the World Health Organisation VA in routine child health programmes. The diagnostic accuracy of the VA tool should also be assessed in other regions and in multicentre studies.Paediatric and Perinatal Epidemiology 09/2008; 22(5):417-29. · 2.31 Impact Factor -
Article: Social costs of skilled attendance at birth in rural Ghana.
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ABSTRACT: To examine the social costs to women of skilled attendance at birth in rural Ghana. Ethnographic data were obtained through participant observation, interviews, case histories, and focus groups and were analyzed alongside data from a birth cohort of 2878 singletons born in the Kintampo study district between July 2003 and June 2004. Most women delivered at home. Home delivery raises a woman's status in her community, while seeking skilled attendance lowers it. Women feel that seeking assistance in childbirth wastes other people's time and they value secrecy in labor. Negative treatment by health providers and expensive supplies needed for delivery also act as barriers. The social costs of obtaining skilled attendance at birth must be offset by community level strategies such as mobilization of older women and husbands, and ensuring health providers extend professional, humane care to laboring women.International Journal of Gynecology & Obstetrics 08/2008; 102(1):91-4. · 2.05 Impact Factor -
Article: The comparative validity of screening scales for postnatal common mental disorder in Kintampo, Ghana.
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ABSTRACT: There have been few attempts formally to validate screening measures for postnatal common mental disorder in low income country settings. We have investigated the comparative validity of three different screening approaches in a community-based study in Kintampo, Ghana. 160 women aged 15-45 years, and 5-11 weeks postpartum were first screened using the Self-Report Questionnaire (SRQ-20), with oversampling of higher scorers. The other test assessments were the Edinburgh Postnatal Depression Scale (EPDS) and the Patient Health Questionnaire (PHQ-9). Criterion validity was measured against the Comprehensive Psychopathological Rating Scale (CPRS), and concurrent validity against the WHO Disability Assessment Schedule. A sub-sample (n=40) was re-interviewed 2 weeks later for test-retest reliability. Internal consistency (Cronbach's Alpha) was equivalent across all three test scales; EPDS (0.79), SRQ-20 (0.78) and PHQ-9 (0.79). Test-retest reliability was better for PHQ-9 (ICC 0.75) than for the EPDS (0.51). For criterion validity the PHQ-9 (AUROC 0.90 (0.81-0.98)), was superior to the SRQ-20 (0.74 (0.62-0.86)) and the EPDS ((0.84 (0.76-0.92). Youden's Index was also superior for PHQ-9. Item analysis revealed that a mixture of somatic and cognitive symptoms best discriminated between cases and non-cases for all three scales. Inability to ascertain inter-rater reliability, order effects and possible loss of technical equivalence due to item modifications. The evidence for the validity, reliability, and superiority of the PHQ-9 over other screening assessments has been extended. The PHQ-9 is short, easy to administer and acceptable to a largely illiterate population of Ghanaian women, 5 to 11 weeks post partum.Journal of Affective Disorders 08/2008; 113(1-2):109-17. · 3.52 Impact Factor -
Article: An open label, randomised trial of artesunate+amodiaquine, artesunate+chlorproguanil-dapsone and artemether-lumefantrine for the treatment of uncomplicated malaria.
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ABSTRACT: Artesunate+amodiaquine (AS+AQ) and artemether-lumefantrine (AL) are now the most frequently recommended first line treatments for uncomplicated malaria in Africa. Artesunate+chlorproguanil-dapsone (AS+CD) was a potential alternative for treatment of uncomplicated malaria. A comparison of the efficacy and safety of these three drug combinations was necessary to make evidence based drug treatment policies. Five hundred and thirty-four, glucose-6-phosphate dehydrogenase (G6PD) normal children were randomised in blocks of 15 to the AS+AQ, AL or AS+CD groups. Administration of study drugs was supervised by project staff and the children were followed up at r home on days 1,2,3,7,14 and 28 post treatment. Parasitological and clinical failures and adverse events were compared between the study groups. In a per-protocol analysis, the parasitological and clinical failure rate at day 28 post treatment (PCF28) was lower in the AS+AQ group compared to the AL or AS+CD groups (corrected for re-infections: 6.6% vs 13.8% and 13.8% respectively, p = 0.08; uncorrected: 14.6% vs 27.6% and 28.1% respectively, p = 0.005). In the intention to treat analysis, the rate of early treatment failure was high in all three groups (AS+AQ 13.3%; AL 15.2%; and AS+CD 9.3%, p = 0.2) primarily due to vomiting. However, the PCF28 corrected for re-infection was lower, though not significantly, in the AS+AQ group compared to the AL or the AS+CD groups (AS+AQ 18.3%; AL 24.2%; AS+CD 20.8%, p = 0.4) The incidence of adverse events was comparable between the groups. AS+AQ is an appropriate first line treatment for uncomplicated malaria in Ghana and possibly in the neighbouring countries in West Africa. The effectiveness of AL in routine programme conditions needs to be studied further in West Africa. ClinicalTrials.gov NCT00119145.PLoS ONE 02/2008; 3(6):e2530. · 4.09 Impact Factor -
Article: Beyond symptom recognition: care-seeking for ill newborns in rural Ghana.
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ABSTRACT: To assess newborn care-seeking practices in a rural area of Ghana where most births take place at home in order to inform potential strategies for reducing newborn mortality. Qualitative, ethnographic study with quantitative data from a birth cohort collected as part of the surveillance system of an ongoing randomized controlled trial. Data collected comprised 84 h of participant observation (including following an ill newborn through a hospital visit), 14 in-depth interviews with key informants (older mothers and grandmothers), 45 semistructured interviews with mothers, 28 case histories from women who had recently given birth and 32 expert interviews with local health providers. Thirteen focus groups were held with men and women, and narrative histories of newborn deaths were taken from eight women. Birth cohort data came from 2878 singletons born alive in the study district within the year July 2003-June 2004. Significant delays in care seeking for ill newborns occur in Kintampo District, Ghana. 2.1% of 2878 newborns in the birth cohort had a serious illness during the first 4 weeks of life, but care was only sought outside the home for 61% of those and from a doctor or hospital for 39%. Barriers to prompt allopathic care seeking include sequential care-seeking practices, with often exclusive use of traditional medicine as first-line treatment for 7 days, previous negative experiences with health service facilities, financial constraints and remoteness from health facilities. Improvements in care seeking are urgently needed. Families should be urged to seek medical care for any symptom of illness in a newborn; financial and socio-cultural barriers to care seeking for newborns must be addressed in order to improve neonatal survival.Tropical Medicine & International Health 02/2008; 13(1):123-8. · 2.80 Impact Factor -
Article: Duration of protection against malaria and anaemia provided by intermittent preventive treatment in infants in Navrongo, Ghana.
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ABSTRACT: Intermittent preventive treatment for malaria in Infants (IPTi) has been shown to give effective and safe protection against malaria. It has been suggested that IPTi might have long-lasting beneficial effects but, in most settings, the protection provided by IPTi appears to be short-lived. Knowledge of the duration of protection given by IPTi would help interpret the results of existing trials and suggest optimal delivery schedules for IPTi. This study investigated how the protective efficacy of IPTi against malaria and anaemia changes over time. A secondary analysis of data from a cluster-randomised, placebo-controlled trial of IPTi using sulfadoxine-pyrimethamine (SP) in Ghana was conducted. In this trial IPTi was given to 2485 infants at 3, 4, 9 and 12 months of age; children remained in follow-up until two years of age. Poisson regression with a random effect to adjust for the cluster-randomised design was used to determine protective efficacy of IPTi against clinical malaria and anaemia in defined time strata following administration of IPTi. Analysis of first-or-only clinical malaria episode following the individual IPTi doses showed that some protection against malaria lasted between 4 to 6 weeks. A similar pattern was seen when the incidence of all malaria episodes up to 2 years of age was analysed in relation to the most recent IPT, by pooling the incidence of malaria after the individual IPTi doses. Protective efficacy within four weeks of IPTi was 75.2% (95% CI: 66-82) against malaria, 78.9% (95% CI: 69-86) against high parasite density malaria, and 93.8% (95% CI: 73-99) against anaemia. Protection against these outcomes was short-lived, with evidence of any effect lasting for only 6, 6 and 4 weeks respectively. Protection in children who were parasitaemic when receiving IPTi appeared to be of shorter duration than in uninfected children. There was no evidence of any benefit of IPTi after the immediate period following the IPTi doses. Intermittent preventive treatment provides considerable protection against malaria and anaemia for short periods, even in an area of intense seasonal transmission. Due to the relatively short duration of protection provided by each dose of IPTi, this treatment will be of most benefit when delivered at the time of peak malaria incidence.PLoS ONE 02/2008; 3(5):e2227. · 4.09 Impact Factor -
Article: Patterns of age-specific mortality in children in endemic areas of sub-Saharan Africa.
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ABSTRACT: Understanding of the age- and season- dependence of malaria mortality is an important prerequisite for epidemiologic models of malaria immunity. However, most studies of malaria mortality have aggregated their results into broad age groups and across seasons, making it hard to predict the likely impact of interventions targeted at specific age groups of children. We present age-specific mortality rates for children aged < 15 years for the period of 2001-2005 in 7 demographic surveillance sites in areas of sub-Saharan Africa with stable endemic Plasmodium falciparum malaria. We use verbal autopsies (VAs) to estimate the proportion of deaths by age group due to malaria, and thus calculate malaria-specific mortality rates for each site, age-group, and month of the year. In all sites a substantial proportion of deaths (ranging from 20.1% in a Mozambican site to 46.2% in a site in Burkina Faso) were attributed to malaria. The overall age patterns of malaria mortality were similar in the different sites. Deaths in the youngest children (< 3 months old) were only rarely attributed to malaria, but in children over 1 year of age the proportion of deaths attributed to malaria was only weakly age-dependent. In most of the sites all-cause mortality rates peaked during the rainy season, but the strong seasonality in malaria transmission in these sites was not reflected in strong seasonality in the proportion of deaths attributed to malaria, except in the two sites in Burkina Faso. Improvement in the specificity of malaria verbal autopsies would make it easier to interpret the age and season patterns in such data.The American journal of tropical medicine and hygiene 12/2007; 77(6 Suppl):99-105. · 2.59 Impact Factor -
Article: Is there any monitoring of the quality of vitamin A capsules used in supplementation programs?
American Journal of Clinical Nutrition 11/2007; 86(4):1254. · 6.67 Impact Factor -
Article: Effect of early infant feeding practices on infection-specific neonatal mortality: an investigation of the causal links with observational data from rural Ghana.
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ABSTRACT: Strong associations between delayed initiation of breastfeeding and increased neonatal mortality (2-28 d) were recently reported in rural Ghana. Investigation into the biological plausibility of this relation and potential causal pathways is needed. The objective was to assess the effect of early infant feeding practices (delayed initiation, prelacteal feeding, established neonatal breastfeeding) on infection-specific neonatal mortality in breastfed neonates aged 2-28 d. This prospective observational cohort study was based on 10 942 breastfed singleton neonates born between 1 July 2003 and 30 June 2004, who survived to day 2, and whose mothers were visited in the neonatal period. Verbal autopsies were used to ascertain the cause of death. One hundred forty neonates died from day 2 to day 28; 93 died of infection and 47 of noninfectious causes. The risk of death as a result of infection increased with increasing delay in initiation of breastfeeding from 1 h to day 7; overall late initiation (after day 1) was associated with a 2.6-fold risk [adjusted odds ratio (adj OR): 2.61; 95% CI: 1.68, 4.04]. Partial breastfeeding was associated with a 5.7-fold adjusted risk of death as a result of infectious disease (adj OR: 5.73; 95% CI: 2.75, 11.91). No obvious associations were observed between these feeding practices and noninfection-specific mortality. Prelacteal feeding was not associated with infection (adj OR: 1.11; 95% CI: 0.66, 1.86) or noninfection-specific (adj OR: 1.33; 95% CI: 0.55, 3.22) mortality. This study provides the first epidemiologic evidence of a causal association between early breastfeeding and reduced infection-specific neonatal mortality in young human infants.American Journal of Clinical Nutrition 11/2007; 86(4):1126-31. · 6.67 Impact Factor -
Article: An evaluation of the immunogenicity and safety of a new trivalent meningococcal polysaccharide vaccine.
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ABSTRACT: The immunogenicity and safety of a meningococcal trivalent A/C/W135 polysaccharide vaccine was compared with that of a tetravalent A/C/Y/W135 polysaccharide vaccine in a randomised, double blind trial. The study included 360 adults, who received either a trivalent or tetravalent polysaccharide meningococcal vaccine. Antibody responses were determined by serum bactericidal antibody (rSBA) assays prior to vaccination and on day 28 and month 11 after vaccination. The percentage of participants in the trivalent vaccine group who had rSBA titres >or=8 on day 28 post-vaccination against serogroups A, C and W135 meningococci were 99, 98 and 91%, respectively. The corresponding figures in the tetravalent vaccine group were 99, 99 and 90%. The percentage of participants with various cut off levels of rSBA against serogroups A, W135 and C meningococci on day 28 and 11-month post-vaccination and the incidence of adverse events did not differ significantly between the two groups.Vaccine 10/2007; 25 Suppl 1:A83-91. · 3.77 Impact Factor -
Article: Need to worry: wrong vitamin A doses reported!
Vaccine 07/2007; 25(23):4514. · 3.77 Impact Factor -
Article: Is the Expanded Programme on Immunisation the most appropriate delivery system for intermittent preventive treatment of malaria in West Africa?
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ABSTRACT: To investigate the coverage and equity of the Expanded Programme on Immunisation (EPI) and its effect on age schedule, seasonality of malaria risk, and linked intermittent preventive treatment (IPT) in West Africa. Secondary analyses of data from a trial of IPT in Ghana. The potential effectiveness and impact of EPI-linked IPT in West Africa was calculated using the coverage of Diptheria Pertussis Tetanus vaccination obtained from national surveys and the reported protective efficacies of IPT. In West Africa, where the transmission of malaria is highly seasonal, only 10% of malaria episodes in infants would be averted with the current coverage of EPI. In this setting, the EPI-linked IPT is not necessarily the most appropriate approach and alternative IPT schedules and delivery systems are needed.Tropical Medicine & International Health 07/2007; 12(6):743-50. · 2.80 Impact Factor
Top co-authors
Top Journals
Institutions
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2008–2013
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Ministry of Health, Ghana
Accra, Greater Accra Region, Ghana
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2006–2013
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London School of Hygiene and Tropical Medicine
- Faculty of Epidemiology and Population Health
London, ENG, United Kingdom
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2012
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Centre for Health Research and Development
New Delhi, NCT, India -
Johns Hopkins Bloomberg School of Public Health
Baltimore, MD, USA
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2009–2012
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Kintampo Health Research Centre
Johannesburg, Gauteng, South Africa
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2011
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Kwame Nkrumah University Of Science and Technology
- School of Medical Sciences
Kumasi, Ashanti Region, Ghana
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2010
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Universität Basel
Basel, BS, Switzerland
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2007
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United States Navy
Washington, WV, USA
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2005
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Swiss Tropical and Public Health Institute
- Department of Epidemiology and Public Health
Basel, BS, Switzerland
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2002–2003
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Navrongo Health Research Centre
Navrongo, Upper East Region, Ghana
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