G Walraven

Medical Research Council Unit, The Gambia Unit, Bakau, Banjul, Gambia

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Publications (51)305.84 Total impact

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    ABSTRACT: We investigated the ability of intermittent preventive treatment in pregnancy (IPTp) with sulphadoxine/pyrimethamine to prevent anaemia and low birthweight in Gambian multigravidae. Between July 2002 and February 2004, 2688 multigravidae living in a rural area of The Gambia received SP (1346 women) or placebo (1342 women) up to four times during pregnancy and were followed until 6-weeks post-partum. Shortly after delivery, 10.7% of women in the intervention group and 8.8% in the control group were severely anaemic [Hb < 7 g/dl, risk difference = 0.02 (95% CI -0.01, 0.04), P = 0.17]. The overall mean birthweight of infants born to women who had received SP (3103 g) was very similar to that observed in infants born to women in the control group [3075 g; difference = 28 g (95% CI -11 g, 67 g), P = 0.16]. However, among women who did not use a bednet (either insecticide treated or untreated), infants born to women who had received SP weighed more than infants born to women in the control group [3147 g vs. 3044 g; difference 143 g (95% CI 53 g, 232 g), interaction test P < 0.001]. This study did not show that IPTp with SP benefited Gambian multigravidae overall but that it may benefit a sub-group of women who do not use a bednet. In areas such as The Gambia, provision of insecticide-treated bednets to multigravidae may provide an adequate means of protection against malaria in pregnancy without the need for additional IPTp.
    Tropical Medicine & International Health 08/2006; 11(7):992-1002. · 2.30 Impact Factor
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    ABSTRACT: The development of effective strategies against cervical cancer in Africa requires accurate type specific data on human papillomavirus (HPV) prevalence, including determination of DNA sequences in order to maximise local vaccine efficacy. We have investigated cervical HPV infection and squamous intraepithelial lesions (SIL) in an unselected cohort of 1061 women in a rural Gambian community. Squamous intraepithelial lesions was diagnosed using cytology and histology, HPV was typed by PCR-ELISA of DNA extracts, which were also DNA sequenced. The prevalence of cervical HPV infection was 13% and SIL were observed in 7% of subjects. Human papillomavirus-16 was most prevalent and most strongly associated with SIL. Also common were HPV-18, -33, -58 and, notably, -35. Human papillomavirus DNA sequencing revealed HPV-16 samples to be exclusively African type 1 (Af1). Subjects of the Wolof ethnic group had a lower prevalence of HPV infection while subjects aged 25-44 years had a higher prevalence of cervical precancer than older or younger subjects. This first report of HPV prevalence in an unselected, unscreened rural population confirms high rates of SIL and HPV infection in West Africa. This study has implications for the vaccination of Gambian and other African populations in the prevention of cervical cancer.
    British Journal of Cancer 11/2005; 93(9):1068-76. · 4.82 Impact Factor
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    ABSTRACT: The prevalence of cervical cancer is extremely high in low income countries, primarily because of a lack of cytological screening. The link between human papillomavirus (HPV) and cervical cancer has long been recognised, and it has been suggested that isolated HPV testing in women who do not participate in existing screening programmes may be used to identify women at higher risk of developing cervical cancer. This community based study compares two self administered techniques for detecting HPV (tampons and self administered swabs) with a clinician directed technique, the cervical cytobrush. 377 rural women were interviewed and of these 210 women had full gynaecological examination, and accepted all three sampling methods for HPV. HPV typing of DNA extracts was performed using polymerase chain reaction and enzyme linked immunosorbent assay techniques. Using the cervical cytobrush as the gold standard, self administered swabs (SAS) showed a sensitivity of 63.9%, and tampons showed a sensitivity of 72.4%. The acceptability of these two tests was 97.1% and 84.6% respectively. When combining acceptability with sensitivity, the SAS detected 61.9% and the tampons detected 60.9% of the true positives. In a setting where women are at a considerable risk of developing cervical cancer, with no access to a formal screening programme, self directed HPV testing could be a useful screening tool in identifying those women at increased risk who may require further investigation.
    Sexually Transmitted Infections 07/2005; 81(3):239-41. · 3.08 Impact Factor
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    ABSTRACT: To examine the occurrence of bacterial vaginosis (BV) over the menstrual cycle and in relation to menstrual protection materials and sexual intercourse in a rural African setting. Married, regularly menstruating female volunteers were asked to collect self administered swabs on alternate days through four menstrual cycles. BV was assessed using Nugent scores. Menstruation and reported sexual intercourse data were recorded contemporaneously. A crossover design comparing traditional and modern menstrual protection methods was incorporated. Multivariate logistic regression was used to examine associations with BV. 30 women completed four menstrual cycles in the study. Completeness and validity of data from the self administered swabs was high. Greater frequencies of BV were found for all women in the second week of the menstrual cycle relative to days 14+, and markedly higher frequencies of BV were found in the first week in women with infrequent BV. BV was (non-significantly) more frequent when modern pads were used compared with traditional cloths. No association was found between BV and intercourse reported in the previous 4 days; or between the frequency of reported intercourse in one menstrual cycle and BV in either the same menstrual cycle or the next. Similar transient fluctuations over the menstrual cycle were found to those in industrialised countries. We found no evidence that sexual intercourse was associated with increased frequency of BV. Our data do not support hypotheses that menstrual hygiene materials might explain the high prevalences of BV found in sub-Saharan Africa compared to industrialised countries.
    Sexually Transmitted Infections 07/2005; 81(3):242-7. · 3.08 Impact Factor
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    ABSTRACT: Process evaluation has become the mainstay of safe motherhood evaluation in developing countries, yet the extent to which indicators measuring access to obstetric services at the population level reflect levels of maternal mortality is uncertain. In this study we examine the association between population indicators of access to obstetric care and levels of maternal mortality in urban and rural West Africa. In this ecological study we used data on maternal mortality and access to obstetric services from two population-based studies conducted in 16 sites in eight West African countries: the Maternal Mortality and Obstetric Care in West Africa (MAMOCWA) study in rural Sénégal, Guinea-Bissau and The Gambia and the Morbidité Maternelle en Afrique de l'Ouest (MOMA) study in urban Burkina Faso, Côte d'Ivoire, Mali, Mauritanie, Niger and Sénégal. In rural areas, maternal mortality, excluding early pregnancy deaths, was 601 per 100,000 live births, compared with 241 per 100,000 for urban areas [RR = 2.49 (CI 1.77-3.59)]. In urban areas, the vast majority of births took place in a health facility (83%) or with a skilled provider (69%), while 80% of the rural women gave birth at home without any skilled care. There was a relatively close link between levels of maternal mortality and the percentage of births with a skilled attendant (r = -0.65), in hospital (r = -0.54) or with a Caesarean section (r = -0.59), with marked clustering in urban and rural areas. Within urban or rural areas, none of the process indicators were associated with maternal mortality. Despite the limitations of this ecological study, there can be little doubt that the huge rural-urban differences in maternal mortality are due, at least in part, to differential access to high quality maternity care. Whether any of the indicators examined here will by themselves be good enough as a proxy for maternal mortality is doubtful however, as more than half of the variation in mortality remained unexplained by any one of them.
    Tropical Medicine & International Health 11/2003; 8(10):940-8. · 2.30 Impact Factor
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    ABSTRACT: To assess the rapid plasma reagin (RPR) test performance in the field and to evaluate a new rapid syphilis test (RST) as a primary screen for syphilis. 1325 women of reproductive age from rural communities in the Gambia were tested for syphilis seropositivity using a RPR 18 mm circle card and a RST strip. Within 1 week a repeat RPR and a TPHA test were carried out using standard techniques in the laboratory. Comparing field tests to a diagnosis of "active" syphilis defined as laboratory RPR and TPHA positive, the RPR test was 77.5% sensitive and 94.1% specific; the RST was 75.0% sensitive and 95.2% specific. The RST was easier to use and interpret than the RPR test especially where field conditions were difficult. In this setting with a low prevalence of syphilis in the community (3%), the chance of someone with a positive test being confirmed as having serologically active syphilis was less than 50% for both tests. The appropriateness of syphilis screening using RPR testing in antenatal clinics and health centres should be questioned if there is a low prevalence in the population, conditions for testing are poor, and resources limited. There is still an urgent need for an appropriate rapid syphilis test for field use.
    Sexually Transmitted Infections 09/2002; 78(4):282-5. · 3.08 Impact Factor
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    ABSTRACT: Cardiovascular disease (CVD) is rapidly becoming an important public health problem in sub-Saharan Africa, yet the response so far is often minimal and inadequate. While there is, undoubtedly, a 'double burden of disease' (persisting infectious diseases co-existing with emerging non-communicable disease), this is hardly reflected in current health planning, possibly due to a limited appreciation of the changing pattern of CVD and CVD risk factor exposure. In a situation where there are also considerable budget constraints and well-established infectious disease priorities, it is difficult to implement effective interventions for prevention or treatment of CVD. Yet such planning is urgently needed and a template for a comprehensive programme, adaptable to local situations, is presented here. The first step is to raise awareness and create evidence-based commitment among policy-makers, which could lead to the establishment of a multi-sectoral CVD unit at national level. Programmes need to focus on prevention of modifiable risk factors at population level, involving a wide range of institutions and individuals. Recommended strategies include decentralizing the design and implementation of programmes, with appropriate standardized surveillance of major risk factors, all complemented by operational, epidemiological and basic research.
    Health Policy and Planning 01/2002; 16(4):345-50. · 3.00 Impact Factor
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    ABSTRACT: Community-based behavioural interventions aimed at reducing risky sexual behaviour have yet to be shown to be effective in the developing world. Stepping Stones is a participatory STI/ HIV prevention workshop programme based on empowerment techniques, which has been adapted to an infertility prevention framework for The Gambia. This paper describes a preliminary evaluation in two villages where the intervention was carried out compared to two control villages. Methods used include: participatory evaluation; 84 in-depth interviews; seven focus group discussions; a knowledge, attitudes and practice questionnaire administered to a random sample of 25% of the adult population at three time points; and monitoring of condom supply. The structure of the evaluation is based on the themes derived from the qualitative data. The infertility prevention approach made it possible to overcome resistance to discussing the topics of sexual and reproductive health. An atmosphere of trust was created and men were persuaded to participate in the programme as they felt that their own needs were being addressed. Participants enjoyed the programme and found the content relevant. Knowledge of the modes of transmission of HIV and sexually transmitted infections and levels of risk awareness increased. The value of condoms in particular situations was recognised: for sex before marriage, within marriage (when the woman is breastfeeding) and with non-marital partners. Women reported that they would insist on condom use outside marriage and even ask their husbands to use condoms for non-marital sex. Condom monitoring data suggested that condom uptake had increased. It was reported that there was significant increase in dialogue within marriage with the consequence that there were fewer disagreements and incidents of domestic violence. Diffusion of the messages of Stepping Stones appeared to have taken place with non-participants including children. The evaluation techniques used can now be refined in order to generate further evidence on a larger scale and over a longer period.
    African Journal of AIDS Research 01/2002; · 0.61 Impact Factor
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    ABSTRACT: A widespread reduction in Plasmodium falciparum gametocyte prevalence could reduce malaria transmission. After infection with P. falciparum, a variable proportion of people are found to be gametocytemic. We analyzed risk factors associated with gametocytemia at presentation and 7 days later. We enrolled 1,198 children in 2 antimalarial drug trials between September and December 1998. The children were assigned to 1 of 4 treatment groups: chloroquine only; pyrimethamine-sulfadoxine (PSD) only; PSD combined with 1 dose of artesunate; and PSD combined with 3 doses of artesunate. By the time of enrollment, 200 (17%) of 1,198 children were gametocyte carriers. Three independent risk factors were associated with gametocytemia at enrollment. Children with anemia were more likely to carry gametocytes, whereas children with fever (> 37.4 degrees C) or high parasite densities (> 100,000 parasites/microL) were less frequently gametocyte carriers. Children with at least 2 of the risk factors were 4 times more likely to be gametocytemic than children with < 2 risk factors (odds ratio [OR], 4.4; 95% confidence interval [CI], 2.7-7.1). Seven days after the start of treatment, 355 (37%) of 466 assessable children were found to be gametocyte carriers. Children treated with PSD alone had a significantly higher risk of being gametocytemic by Day 7 compared with children in the other 3 treatment groups. In the subgroup of children who had no detectable gametocytes on enrollment, the effect of treatment with PSD + 3 doses of artesunate was most marked. Nineteen (10%) of 198 children treated with PSD + 3 doses of artesunate became gametocytemic, in contrast to 184 (57%) of 321 children treated with PSD alone (OR, 12.7; 95% CI, 7.3-22.1). Early treatment with highly effective antimalarial therapy has the greatest chance of preventing gametocytemia. The choice of a first-line antimalarial drug for uncomplicated malaria should not only take into consideration the ablation asexual parasitemia but also the suppression of gametocytemia.
    The American journal of tropical medicine and hygiene 11/2001; 65(5):523-7. · 2.74 Impact Factor
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    ABSTRACT: Asthma is reported to be rare in traditional rural communities, but is thought to be increasing as lifestyles become more urbanized or 'western'. A community-based survey of non-communicable diseases was conducted from October 1996 to June 1997, and included comparison of the prevalence of asthma, smoking and chronic cough in rural and urban Gambia. A cluster sample survey was conducted in a random sample of rural and urban adults (> or = 15 years of age). Subjects were asked about respiratory symptoms using a locally adapted version based on the IULTD questionnaire. Spirometry (basal, methacholine provocation and reversibility with a bronchodilator) and skin prick tests were performed on a randomly selected subsample of all subjects and those who, when interviewed, said they wheezed or had been diagnosed as asthmatic by a doctor. Out of 2166 participants in the urban population, 4.1% reported having had wheezing or whistling in the chest in the previous 12 months, 3.6% reported doctor-diagnosed asthma, and 0.6% chronic cough. In the rural population with 3223 participants these figures were 3.3%, 0.7% and 1.2%, respectively. Wheeze was more common in women, cough for 3 months of the year was more common in the age-groups 45+. Those who reported that they currently smoked accounted for 34% in urban and 42% in rural men. Figures were much lower for women (1.5% and 6.0%). Seven out of 574 randomly selected subjects (1.4%) exhibited bronchial hyper-responsiveness to methacholine challenge. Four of 133 (3.0%) people with self-reported wheeze and 3/69 (4.3%) participants with doctor-diagnosed asthma reacted positively on bronchial provocation with methacholine. There was a remarkably high prevalence of positive skin prick tests to aeroallergens: 38% in participants with a history of wheeze and 27% in those without. The prevalence of wheeze (particularly in association with bronchial hyper-responsiveness) was low in both rural and urban Gambia. This is in contrast to the relatively high prevalence of positive skin prick tests to aeroallergens (in both wheezers and non-wheezers), questioning the mechanisms of interaction between allergy and asthma and the presence of protective factors against asthma in this West African population. The high smoking rates justify international concern about tobacco marketing in developing societies.
    Clinical & Experimental Allergy 11/2001; 31(11):1679-85. · 4.32 Impact Factor
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    ABSTRACT: The rarity of atopy in traditional societies has been attributed to high parasite-driven blocking IgE concentrations. Information is lacking on the relationship between atopy, IgE and intestinal helminth infection in African populations. To determine the prevalence of atopy and intestinal helminth infection and to relate these to wheeze history and serum total IgE in a community sample of adults from an urban (Banjul) and a rural (Farafenni) area of the Gambia. Six hundred and ninety-three adults were interviewed about respiratory symptoms using a modified version of the IUTLD questionnaire, and had skin prick testing using four allergens. Stools were examined after formol-ether concentration. Total serum IgE concentration was measured in a subset of participants. The prevalence of atopy (mean weal diameter > or = 3 mm) in the urban and rural area was 35.3% and 22.5% (P = 0.05); D. pteronyssinus and Mold mix being the common sensitizing allergens. Prevalence of wheeze in the previous 12 months was 4.4% and 3.5% for the urban and rural areas, respectively. Wheezing was not significantly associated with atopy. Seventeen per cent of urban and 8.2% of rural subjects had helminths detected in stools. There was an inverse association between atopy and intestinal helminth infection; 7% of atopic subjects had helminths, compared to 13% of non-atopic subjects (unadjusted odds ratio 0.51, 95%CI 0.24-1.1, P = 0.09; adjusted odds ratio 0.37, 95%CI 0.15-0.92, P = 0.03). Non-atopics had total serum IgE concentrations about 2.5 times the upper limit of the reference range in non-atopic Western populations. Geometric mean total serum IgE concentration was significantly higher among atopic subjects (570 IU/mL, IQR 91-833) than non-atopic subjects (259 IU/mL, IQR 274-1303) (P < 0.001). IgE concentration was not associated with the presence of helminth infection. Further studies are needed to clarify why asthma is still relatively uncommon in spite of the prevalence of atopy in Gambian adults. Our data are also compatible with the idea that atopy might protect against helminth infection.
    Clinical & Experimental Allergy 11/2001; 31(11):1672-8. · 4.32 Impact Factor
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    ABSTRACT: To estimate prevalence and risk factors for herpes simplex 2 (HSV2) positivity, syphilis and Chlamydia trachomatis infection among rural people aged 15-34 in the Gambia. Questionnaires and serum samples were collected from 1076 men and women aged 15-34 during a cross sectional prevalence survey in a rural area of the Gambia. Sera were screened for antibodies to herpes simplex virus type 2 (HSV2), and for syphilis using Treponema pallidum haemagglutination assay (TPHA) and rapid plasma reagin (RPR) tests. Urine was tested by polymerase chain reaction (PCR) for C trachomatis infection. 28% of women and 5% of men were HSV2 ELISA positive; 10% of women and 2% of men were TPHA positive; and 7% of women and 1% of men were both RPR and TPHA positive. Out of 1030 urine sample tested only six were positive for C trachomatis. 7% of those who reported never having sex were positive for one or other of these tests. Prevalences of all STIs increased with age and were higher in women than men. Women were much less likely than men to seek treatment for STI symptoms at a health centre. Married people were at increased risk of an STI compared with single people. Jola and Fula women had a higher prevalence of HSV2 than women from other ethnic groups, and Fulas also had a higher prevalence of RPR/TPHA positivity. The limited number of sexual behaviour questions were not significantly associated with STIs after adjustment for age, marital status, and ethnic group. The prevalences of the ulcerative infections HSV2 and syphilis in this population are a cause for concern. In a setting where HIV1 prevalence remains low this indicates an urgent need for STI control and behaviour change programmes to prevent an HIV epidemic. Concerns about the validity of reported sexual behaviour data high light the necessity of biological markers in the evaluation of behaviour change programmes.
    Sexually Transmitted Infections 11/2001; 77(5):358-65. · 3.08 Impact Factor
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    P M Emerson, R L Bailey, G. E. L. Walraven, S W Lindsay
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    ABSTRACT: The fly Musca sorbens Wiedemann (Diptera: Muscidae) apparently transmits Chlamydia trachomatis, causing human trachoma. The literature indicates that M. sorbens breeds predominantly in isolated human faeces on the soil surface, but not in covered pit latrines. We sought to identify breeding media of M. sorbens in a rural Gambian village endemic for trachoma. Test breeding media were presented for oviposition on soil-filled buckets and monitored for adult emergence. Musca sorbens emerged from human (6/9 trials), calf (3/9), cow (3/9), dog (2/9) and goat (1/9) faeces, but not from horse faeces, composting kitchen scraps or a soil control (0/9 of each). After adjusting for mass of medium, the greatest number of flies emerged from human faeces (1426 flies/kg). Median time for emergence was 9 (inter quartile range = 8-9.75) days post-oviposition. Of all flies emerging from faeces 81% were M. sorbens. Male and female flies emerging from human faeces were significantly larger than those from other media, suggesting that they would be more fecund and live longer than smaller flies from other sources. Female flies caught from children's eyes were of a similar size to those from human faeces, but significantly larger than those from other media. We consider that human faeces are the best larval medium for M. sorbens, although some breeding also occurs in animal faeces. Removal of human faeces from the environment, through the provision of basic sanitation, is likely to greatly reduce fly density, eye contact and hence trachoma transmission, but if faeces of other animals are present M. sorbens will persist.
    Medical and Veterinary Entomology 10/2001; 15(3):314-20. · 2.33 Impact Factor
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    ABSTRACT: Hypertension has become an important public health problem for sub-Sahara Africa. In a previous nationwide study, we observed a high degree of geographical variation in the prevalence of diastolic hypertension. Geographical variation provides essential background information for the development of community randomised trials could suggest aetiological mechanisms, inform control strategies and prompt further research questions. We designed a follow-up study from the nine high-prevalence communities, and from 18 communities where hypertension was found least prevalent (controls). In each community, 50 households were randomly selected. In each household, an (unrelated) man and woman were enrolled. The risk for hypertension (blood pressure > or =160/95 mm Hg) was higher in the high prevalence communities compared to the control villages (adjusted OR = 1.7, 95% CI 1.3-2.2). The observed coefficient of variation in hypertension prevalence, k, was 0.30. Thus we confirmed significant geographical variation in prevalence of hypertension over time, which has implications for planning of interventions.
    Journal of Human Hypertension 10/2001; 15(10):733-9. · 2.69 Impact Factor
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    ABSTRACT: This study documented the prevalence of and cardiovascular risk factors associated with obesity and undernutrition in the Gambia. Adults (> or =15 years; N = 5373) from rural and urban areas completed a questionnaire; their height, weight, and waist and hip circumferences were measured, and their cardiovascular risk factors were assessed. Prevalence of undernutrition (body mass index < 18 kg/m(2)) was 18.0%; all strata of society were affected. Prevalence of obesity (body mass index > or =30 kg/m(2)) was 4.0% but was higher (32.6%) among urban women 35 years or older. Cardiovascular risk factors were more prevalent among obese participants. Undernutrition coexists with obesity, demonstrating a "double burden of disease." Differential interventions should focus on high-risk groups; prevention needs a multisectorial approach.
    American Journal of Public Health 10/2001; 91(10):1641-4. · 4.23 Impact Factor
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    ABSTRACT: This paper examines the association between traditional practices of female genital cutting (FGC) and adult women's reproductive morbidity in rural Gambia. In 1999, we conducted a cross-sectional community survey of 1348 women aged 15-54 years, to estimate the prevalence of reproductive morbidity on the basis of women's reports, a gynaecological examination and laboratory analysis of specimens. Descriptive statistics and logistic regression were used to compare the prevalence of each morbidity between cut and uncut women adjusting for possible confounders. A total of 1157 women consented to gynaecological examination and 58% had signs of genital cutting. There was a high level of agreement between reported circumcision status and that found on examination (97% agreement). The majority of operations consisted of clitoridectomy and excision of the labia minora (WHO classification type II) and were performed between the ages of 4 and 7 years. The practice of genital cutting was highly associated with ethnic group for two of the three main ethnic groups, making the effects of ethnic group and cutting difficult to distinguish. Women who had undergone FGC had a significantly higher prevalence of bacterial vaginosis (BV) [adjusted odds ratio (OR)=1.66; 95% confidence interval (CI) 1.25-2.18] and a substantially higher prevalence of herpes simplex virus 2 (HSV2) [adjusted OR=4.71; 95% CI 3.46-6.42]. The higher prevalence of HSV2 suggests that cut women may be at increased risk of HIV infection. Commonly cited negative consequences of FGC such as damage to the perineum or anus, vulval tumours (such as Bartholin's cysts and excessive keloid formation), painful sex, infertility, prolapse and other reproductive tract infections (RTIs) were not significantly more common in cut women. The relationship between FGC and long-term reproductive morbidity remains unclear, especially in settings where type II cutting predominates. Efforts to eradicate the practice should incorporate a human rights approach rather than rely solely on the damaging health consequences.
    Tropical Medicine & International Health 09/2001; 6(8):643-53. · 2.30 Impact Factor
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    ABSTRACT: To test the hypothesis that widespread treatment with artemisinin derivatives can reduce malaria transmission, a mass drug administration (MDA) campaign was undertaken in an area of The Gambia in 1999. Coverage of 85% of the target population was achieved, but the intervention did not reduce overall malaria transmission. We studied the perceptions, knowledge and attitudes of the community to the MDA campaign. A validated questionnaire was administered to randomly selected MDA participants (n = 90) and MDA refusers (n = 71). Individuals who believed in the importance of the MDA (adjusted OR 58.3%; 95% CI 17.4-195.8) and those who were aware that a high level of participation was needed for the MDA to be successful (adjusted OR 28.1; 95% CI 10.3-75.9) were more likely to participate. Understanding that the purpose of the MDA was to reduce malaria (adjusted OR 13.9; 95% CI 5.5-35.1) and knowledge of the fact that malaria is transmitted by mosquitoes and of the clinical signs of malaria (adjusted OR 3.4; 95% CI 3.1-9.0) were associated with participation. Individuals who discussed the MDA with other villagers (adjusted OR 5.5; 95% CI 2.2-13.5) and those who attended the sensitization meeting (adjusted OR 2.6; 95% CI 1.1-6.0) were also more likely to participate. Women were significantly more likely to participate in the MDA than men (adjusted OR 3.1; 95% CI 1.5-6.2). Individuals who refused to participate were unlikely to plan participation in future MDAs. One of the most difficult challenges in the implementation of a malaria control strategy such as an MDA is to convince villagers to participate and to make them aware that a high level of participation by the community is needed for success. We found that our sensitization meetings could be improved by giving more information on how the MDA works and finding means to generate small group discussions after the meeting.
    Tropical Medicine & International Health 07/2001; 6(6):442-8. · 2.30 Impact Factor
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    ABSTRACT: Combination therapy that includes artemisinin derivatives cures most falciparum malaria infections. Lowering transmission by reducing gametocyte infectivity would be an additional benefit. To examine the effect of such therapy on transmission, Gambian children with Plasmodium falciparum malaria were treated with standard regimens of chloroquine or pyrimethamine-sulfadoxine alone or in combination with 1 or 3 doses of artesunate. The infectivity to mosquitoes of gametocytes in peripheral blood was determined 4 or 7 days after treatment. Infection of mosquitoes was observed in all treatment groups and was positively associated with gametocyte density. The probability of transmission was lowest in those who received pyrimethamine-sulfadoxine and 3 doses of artesunate, and it was 8-fold higher in the group that received pyrimethamine-sulfadoxine alone. Artesunate reduced posttreatment infectivity dramatically but did not abolish it completely. The study raises questions about any policy to use pyrimethamine-sulfadoxine alone as the first-line treatment for malaria.
    The Journal of Infectious Diseases 05/2001; 183(8):1254-9. · 5.78 Impact Factor
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    ABSTRACT: As part of a study to assess the infectivity of gametocytes after treatment with four antimalarial regimens, the efficacy of each treatment was also determined. From September to December 1998, 598 children with uncomplicated malaria were treated; 135 received chloroquine (CQ) alone, 276 received pyrimethamine/sulfadoxine (Fansidar, PSD) alone, 113 received PSD with a single dose of artesunate (PSD + 1ART) and 74 received PSD combined with three doses of artesunate (PSD + 3ART). On day 28 19/63 (30.2%; 95% C.I. 19.2% to 43.1%) of children treated with CQ alone, 5/134 (3.7%; 95% C.I. 1.2% to 8.5%) treated with PSD alone, 1/71 (1.4%, 95% C.I. 0.0% to 7.9%) treated with PSD + 1ART and 0/45 (0.0%; 95% C.I. 0.0% to 7.9%) treated with PSD + 3ART were parasitaemic. The proportion of children with gametocytes on day 7 after treatment with CQ alone was 16/89 (18.0%; 95% C.I. 10.6% to 27.6%), 98/174 (56.3%; 95% C.I. 48.6% to 63.8%) after treatment with PSD alone, 8/70 (11.4%; 95% C.I. 5.1% to 21.3%) after treatment with PSD + 1ART and 4/46 (8.7%; 95% C.I., 2.4% to 20.8%) after treatment with PSD + 3ART. CQ thus has a lower efficacy than PSD or either of the PSD and artesunate combinations. Use of PSD alone as an alternative first line treatment results in a very high post-treatment gametocyte prevalence that is likely to enhance transmission. There would be greater and more sustainable benefits from using PSD and artesunate combinations.
    Tropical Medicine & International Health 03/2001; 6(2):92-8. · 2.30 Impact Factor

Publication Stats

2k Citations
305.84 Total Impact Points

Institutions

  • 1997–2006
    • Medical Research Council Unit, The Gambia Unit
      Bakau, Banjul, Gambia
  • 2001–2005
    • London School of Hygiene and Tropical Medicine
      • Tropical Epidemiology Group (TEG)
      London, ENG, United Kingdom
  • 2000
    • Harvard University
      • Harvard Center for Population and Development Studies
      Cambridge, MA, United States
    • Durham University
      • School of Biological and Biomedical Sciences
      Durham, England, United Kingdom