Research Articles
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A research article reports the results of original research, assesses its contribution to the body of knowledge in a given area, and is published in a peer-reviewed scholarly journal. The faculty publications through published and on-going articles/researches are captured in this community
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Item Newborn screening for sickle cell disease in ghana: 270(Pediatric Research, 2005-08) Ohene-Frempong, K.; Bonney, A.; Tetteh, H.; Nkrumah, F.K.Screening of newborns for SCD allows early initiation of prophylactic therapy, parental education, and comprehensive management, resulting in reduced mortality. Since April 1993, a demonstration project to develop and implement a program of newborn screening for SCD has been conducted in Kumasi (Ghana) by the Comprehensive Sickle Cell Center, the Children's Hospital of Philadelphia (CHOP), in collaboration with the Ministry of Health and other institutions in Ghana. Methodology: Babies are screened at birth or at well-baby visits within days or a few weeks after birth. Mothers are asked to come for results within 4 weeks and failing that, an extensive tracking system is used to deliver results to the homes of families with babies with possible-SCD (P-SCD). Tracking relies solely on information obtained from mothers at the time of screening. The goal is to enroll P-SCD babies into the sickle cell clinic by eight weeks of age. Pregnant women, parents with children and the general public are regularly educated about the screening program. Children with SCD receive comprehensive care through the Sickle Cell Clinic at Komfo Anokye Teaching Hospital. Results: From February 13, 1995 (when newborn testing was started) to December 31, 2004, a total of 177,283 babies were screened through 8 public health institutions and 11 private clinics in Kumasi and one maternity centre in Tikrom, a nearby, rural community. A total of 3,346 (1.9%) babies were identified as having P-SCD with the following Hb phenotypes by isoelectric focusing: 1,847 (1.04%) FS; 1,478 (0.83%) FSC; 6 (0.003%) FSA; and 15 (0.008%) Other. Screening and Tracking Results: Feb. 1995 – Dec. 2004 Conclusions: Screening and follow-up of newborns for sickle cell disease is feasible in a developing country in Africa. Extra effort in tracking is necessary to ensure that babies with disease are found early and referred for medical management.Item Highly symptom-aware children were heavily infected with urinary schistosomiasis in southern Ghana(The Central African Journal of Medicine, 2003) Wagatsuma, Y.; Aryeetey, M.E.; Nkrumah, F.K.; Sack, D.A.; Kojima, SOBJECTIVES: To assess the relationship between the infection status of children and their knowledge, attitudes, beliefs, and practices (KABP) related to urinary schistosomiasis. DESIGN: Questionnaire survey. SETTING: Nine schools in eight rural communities (total population: 4,636) in Ga and South Akuapem Districts, Ghana. SUBJECTS: Four hundred and six children attending primary and secondary schools. MAIN OUTCOME MEASURE: Schistosoma haematobium infection status of children and their KABP. RESULTS: Of 354 children who responded and also submitted their urine samples, 297 (83.9%) tested positive for S. haematobium and the intensity of infection was 90 (95% CI: 74 to 110) eggs per 10 ml urine. General knowledge variables such as the knowledge of symptoms (p < 0.001), and knowledge of swimming or bathing in the river as a transmission route (p < 0.001) showed significant association for higher prevalence and intensity of infection. Treatment-seeking behaviour was not associated with the lower prevalence or intensity of infection. Practice variables such as washing clothes in the stream (p < 0.001) and fishing in the stream (p < 0.01) were significantly associated with both higher prevalence and higher intensity of infection. Children who knew of contact with river water as a transmission route reported more water contact activities (p < 0.001). CONCLUSION: This study showed that highly symptom-aware people were heavily infected, and people frequently exposed to infested water were heavily infected. Moreover, highly symptom-aware people never constituted a group whose exposure was slight. Why was awareness of disease symptoms and general knowledge of the disease not linked to low infectivity? Why didn't awareness result in avoidance of infested water sources? This report highlights the urgent need to address these important questions in future research.Item Lack of association between maternal antibody and protection of African infants from malaria infection.(Infection and Immunity, 2000) Riley, E.M.; Wagner, G.E.; Ofori, M.F.; Wheeler, J.G.; Akanmori, B.D.; Tetteh, K.; McGuinness, D.; Bennett, S.; Nkrumah, F.K.; Anders, R.F.; Koram, K.A.Maternally derived antibodies are believed to protect infants against infection, but there is little direct evidence for a protective role of passively acquired antibodies against malaria. A longitudinal study of malaria infection in 143 infants was conducted in a region of southern Ghana where Plasmodium falciparum is endemic. Infants born in the high-transmission season were less likely to become infected in the first 20 weeks of life than children born in the low-transmission season. Plasma, obtained at birth, was tested for immunoglobulin G (IgG) and IgG subclasses to P. falciparum schizonts and recombinant circumsporozoite antigen, MSP-1 19, MSP-2, AMA-1, and Pf155 (also called ring-infected erytrocyte surface antigen). Antibody levels at birth were not associated with resistance to malaria infection. On the contrary, antibodies at birth were positively associated with infection, indicating that high levels of maternally derived antibodies represent a marker for intensity of exposure to malaria infection in infants. However, all five children who experienced high-density infections (>100 parasites/?l of blood) were seronegative for MSP-1 19 at the time of infection.Item Incidence of symptomatic and asymptomatic plasmodium falciparum infection following curative therapy in adult residents of northern Ghana.(American Journal of Tropical Medicine and Hygiene, 2001) Owusu-Agyei, S.; Koram, K.A.; Baird, J.K.; Utz, G.C.; Binka, F.N.; Nkrumah, F.K.; Fryauff, D.J.; Hoffman, S.L.Adult residents of holoendemic malaria regions in Africa have a naturally acquired immunity (NAI) to malaria that renders them more resistant to new infections, limits parasitemia, and reduces the frequency and severity of illness. Given such attributes, it is not clear how one might evaluate drug or vaccine efficacy in adults without serious confounding. To determine symptomatic and asymptomatic malaria attack rates in adults of northern Ghana, 197 men and women underwent curative therapy for any pre-existing malaria infections at the start of the high transmission (wet) season. They were monitored for first parasitemia and first clinical episode of infection by Plasmodium falciparum over a 20-week period (May-October 1996). The cumulative incidence of primary infection by P. falciparum was 0.98 and incidence density of infection was calculated to be 7.0 cases/person-year. Symptoms were reported by 19.5% of the individuals at the time of first recurrent parasitemia. Incidence of infection, parasite density, and the frequency of symptoms were comparable in males and females. The results suggest that NAI did not provide these adults with significant defense against rapid re-infection and suggest that this population-infection design could serve to demonstrate the efficacy of a drug or vaccine in preventing parasitemia.Item Characteristics of severe anemia and its association with malaria in young children of the Kassena-Nankana district of northern Ghana.(American Journal of Tropical Medicine and Hygiene, 2002) Owusu-Agyei, S.; Fryauff, D.J.; Chandramohan, D.; Koram, K.A.; Binka, F.N.; Nkrumah, F.K.; Utz, G.C.; Hoffman, S.L.Severe anemia is thought to be the principal underlying cause of malaria death in areas of intense seasonal malaria transmission such as the Kassena-Nankana District of northern Ghana. Factors associated with severe anemia in young children, 6-24 months old, were elucidated by analyzing results of 2 malaria-associated anemia surveys (1996, 2000), separated by 4 years, but conducted in the same community and at the same seasonal time point. Age-adjusted comparison confirmed that the proportion of severely anemic children and overall mean hemoglobin (Hb) levels in the November 2000 sample were significantly improved over those of the 1996 sample (17.5 versus 26.4%, P = 0.03; Hb 7.5 versus 6.9 g/dL, P = 0.002). Weight-for-age Z-scores also indicated a significant improvement in the 2000 sample (-1.93 versus -2.20, P < 0.05). Independently, each survey identified statistically significant associations between severe anemia and age, parasite rate, fever, and sex. Relative to children with Hb > or = 6.0 g/dL, those with severe anemia (Hb < 6.0 g/dL) were older, more frequently parasitemic (odds ratio [OR], 1.60; 95% confidence interval [CI], 1.08-2.35), more often febrile (OR, 2.44; 95% CI, 1.71-3.48), and predominantly male (OR, 1.50; 95% CI, 1.05-2.13). An association was identified in both surveys between severe anemia and residence in the northern part of the district, but no clear link was observed in relation to irrigation. Blood transfusions, a likely surrogate index of severe anemia in young children, followed a distinct seasonal pattern. Evidence suggests that dramatic peaks and troughs of severe anemia are regular and possibly predictable events that may be used to gauge the health and survival of young children in this area.Item Predicting the timing of second praziquantel treatment and its effect on reduction of egg counts in southern Ghana. Nsowah-(Acta Tropica, 2004) Nsowah-Nuamah, N.N.N.; Aryeetey, M.E.; Jolayemi, E.T.; Wagatsuma, Y.; Mensah, G.; Dontwi, I.K.; Nkrumah, F.K.; Kojima, S.Schistosoma haematobium infection could be associated with morbidity. Generally, the cost of schistosomiasis control is high and it becomes a burden for governments or non-governmental organisations to repeat control programs so as to reduce morbidity. There is therefore, the need to optimise the available meagre resources for its control. From 1993 to 1997 the Noguchi Memorial Institute for Medical Research of the University of Ghana carried out a schistosomiasis control program in southern Ghana. Using the generated data, an attempt is made to determine the timing of the second praziquantel treatment and the period needed after the second chemotherapy to have egg counts reduced to low levels in southern Ghana. It was revealed that the second praziquantel treatment in areas 1, 2, and 3 should be administered latest at 13.8, 11.8 and 13.2 months, respectively after the first one. Most importantly, it takes 24.4 months to bring egg counts to zero in area 3 while in area 1, it takes about 29 months after the second praziquantel treatment. Egg counts were not reduced to zero in area 2 after the second chemotherapy. At least passive health education and continuous safe water supply should support the chemotherapy in addition to weed removal at the water contact sites.Item A multilateral effort to develop DNA vaccines against falciparum malaria.(Trends in Parasitology, 2002) Kumar, S.; Epstein, J.E.; Richie, T.L.; Nkrumah, F.K.; Soisson, L.; Carucci, D.J.; Hoffman, S.L.Scientists from several organizations worldwide are working together to develop a multistage, multigene DNA-based vaccine against Plasmodium falciparum malaria. This collaborative vaccine development effort is named Multi-Stage DNA-based Malaria Vaccine Operation. An advisory board of international experts in vaccinology, malariology and field trials provides the scientific oversight to support the operation. This article discusses the rationale for the approach, underlying concepts and the pre-clinical development process, and provides a brief outline of the plans for the clinical testing of a multistage, multiantigen malaria vaccine based on DNA plasmid immunization technology.Item Severe anemia in young children after high and low malaria transmission seasons in the Kassena-Nankana district of northern Ghana.(American Journal of Tropical Medicine and Hygiene, 2000) Koram, K.A.; Owusu-Agyei, S.; Utz, G.; Binka, F.N.; Baird, J.K.; Hoffman, S.L.; Nkrumah, F.K.Malaria and anemia accounted for 41% and 18% respectively of hospital deaths in the Kassena-Nankana district of northern Ghana during 1996. We measured hemoglobin (Hb), malaria prevalence, and anthropometric indices of 6—24-month-old infants and young children randomly selected from this community at the end of the high (May–October, n 347) and low (November–April, n 286) malaria transmission seasons. High transmission season is characterized by rainfall (the equivalent of 800–900 mm/yr.), while the remaining months receive less than 50 mm/yr. Severe anemia, defined as Hb 6.0 g/dL, was 22.1% at the end of the high transmission season compared to 1.4% at the end of the low transmission season (Odds Ratio [OR] 20.1; 95% CI: 7.1–55.3). Parasitemia was 71% and 54.3% at these time points (OR 2.1; 95% CI: 1.5–2.9). Nutritional anemia appeared to have little impact upon this seasonal difference since anthropometric indices were comparable. Although the relative contributions of other causes of severe anemia were not assessed, repeated malaria infections may be a primary determinant of severe anemia among infants and young children during the high transmission season.Item Seasonal profiles of malaria infection, anaemia, and bednet use among age groups and communities in northern Ghana.(Tropical Medicine and International Health, 2003) Koram, K.A.; Owusu-Agyei, S.; Fryauff, D.J.; Anto, F.; Atuguba, F.; Hodgson, A.; Hoffman, S.L.; Nkrumah, F.K.We conducted all-age point prevalence surveys to profile the severity and seasonality of malaria and anaemia in Kassena-Nankana District of northern Ghana. Random cross-sectional surveys were timed to coincide with the end of low (May 2001) and high (November 2001) malaria transmission seasons and to yield information as to the potential value of haemoglobin (Hb) levels and parasitaemia as markers of malaria morbidity and/or malaria vaccine effect. Parasitaemia was found in 22% (515 of 2286) screened in May (dry-low transmission), and in 61% of the general population (1026 of 1676) screened in November (wet-high transmission). Malaria prevalence in May ranged from 4% (infants <6 months and adults 50–60 years) to 54% (children 5–10 years). Age-specific malaria prevalence in November ranged from 38% (adults 50–60 years) to 82% (children 5–10 years). Differences between low- and high-transmission periods in the prevalence of severe anaemia (SA) among young children (6–24 months) were unexpectedly comparable (low, 3.9%vs. high, 5.4%; P = 0.52) and greatly reduced from levels measured in this same community and age group in November 2000 (12.5%) and November 1996 (22.0%). Despite the lower frequency of anaemia/SA in young children surveyed in 2001, it was still clear that this condition was strongly associated with parasitaemia and that children under 5 years of age experienced a significant drop in their mean Hb levels by the end of the high transmission season. Prevalence of parasitaemia was significantly lower (P < 0.01) among infants and young children (<2 years) whose parents reported the use of bednets. There was a significantly lower risk of parasitaemia among infants [odds ratio (OR) 6–8] and young children (OR 3–4) living in the central, more urbanized sector of the study area.Item High frequency of circulating γδ T cells with dominance of the V(δ)1 subset in a healthy population.(International Immunology, 2000) Hviid, L.; Akanmori, B.D.; Loizon, S.; Kurtzhals, J.A.L.; Ricke, C.H.; Lim, A.; Koram, K.A.; Nkrumah, F.K.; Mercereau-Puijalon, O.; Behr, C.TCR γδ+ cells constitute <5% of all circulating T cells in healthy, adult Caucasians, and Vδ1+ cells constitute a minority of these cells. In contrast to TCR αβ+ cells, their repertoire is selected extrathymically by environmental antigens. Although increased frequencies of Vδ1+ cells are found in several diseases, their function remains obscure. Here we show that the frequency of peripheral blood γδ T cells in healthy West Africans is about twice that of Caucasians, mainly due to a 5-fold increase in Vδ1+ cells, which is consequently the dominant subset. No age dependency of Vδ1 frequencies was identified and the Vδ1+ cells in the African donors did not show preferential Vγ chain usage. Analysis of the CDR3 region size did not reveal any particular skewing of the Vδ1 repertoire, although oligoclonality was more pronounced in adults compared to children. The proportions of CD8+, CD38+ and CD45RAhiCD45RO– cells within the Vδ1+ subset were higher in the African than in the European donors, without obvious differences in expression of activation markers. No significant correlations between levels of Vδ1+ cells and environmental antigens or immunological parameters were identified. Taken together, the evidence argues against a CDR3-restricted, antigen-driven expansion of Vδ1+ cells in the African study population. Our study shows that high frequencies of TCR γδ+ cells with dominance of the Vδ1+ subset can occur at the population level in healthy people, raising questions about the physiological role of Vδ1+ T cells in the function and regulation of the immune system.