Profile of the navrongo health and demographic surveillance system

Located in the Kassena-Nankana districts of northern Ghana, the Navrongo health and demographic surveillance system (NHDSS) was established in 1992 by the Navrongo health research centre (NHRC). The NHRC is one of three research centres of the Ghana health service. The activities and potential of the NHDSS for collaborative research are described. The NHDSS monitors health and demographic dynamics of the two Kassena-Nankana districts of northern Ghana and facilitates evaluation of the morbidity and mortality impact of health and social interventions. The total population currently under surveillance is 152 000 residing in 32 000 households. Events monitored routinely include pregnancies, births, morbidity, deaths, migration, marriages and vaccination coverage. Data updates are done every 4 months by trained fieldworkers. The NHRC also undertakes biomedical and socio-economic studies. Additional features of the NHDSS include the community key informant system where trained volunteers routinely report key events, such as births and deaths as they occur in their locality and the verbal autopsy (VA) system for determining the probable causes of deaths that occur at the community level. Data from the NHDSS are shared with funders and collaborators and partners in the INDEPTH Network. The Director of the NHDSS is the contact person for potential collaboration with the NHDSS and the use of its data.     

Molecular characterization of a novel form of (A gamma delta beta)zero thalassemia deletion in a Chinese family

We have identified and molecularly characterized a novel deletion in the beta-globin gene cluster that is associated with elevated fetal hemoglobin in the adult. The propositus is a homozygote from the Yunnan province of China. The deletion spans about 90 kb of DNA and removes the A gamma, delta, and beta-globin genes. The 5' breakpoint of the deletion is located about 0.13 kb upstream from the A gamma-globin gene, whereas the 3' breakpoint is located about 66 kb downstream from the beta-globin gene, about 13 kb upstream from the breakpoint of the Chinese (A gamma delta beta)zero-thalassemia. Heterozygotes for this Yunnanese form of (A gamma delta beta)zero-thalassemia express between 9% and 17% of fetal hemoglobin, whereas the homozygote present with a mild anemia (Hb = 10.7 g/dl). Comparison of the sites of 3' breakpoints of the Yunnanese and the Chinese (A gamma delta beta)zero-thalassemia mutants is compatible with the hypothesis that an enhancer element is located between the 3' breakpoints of these two mutants. Juxta-position to the G gamma gene of this element may be responsible for the efficient gamma-gene expression in the Yunnanese mutant.     

Characteristics of severe anemia and its association with malaria in young children of the Kassena-Nankana District of northern Ghana

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.     

The cost-effectiveness of permethrin impregnated bednets in preventing child mortality in Kassena-Nankana district of Northern Ghana

Permethrin impregnated bednets are now being widely promoted as an effective means of protecting African children against malaria, but there is little evidence of their cost-effectiveness. The impact on child mortality of introducing permethrin impregnated bednets was evaluated in a rural district of northern Ghana in a controlled trial. The cost-effectiveness of the intervention is reported in this paper. The total cost of the intervention over the 2 years of follow-up was US $148,245. Cost per impregnated bednet per year and per person protected per year was US $2.4 and 1.2, respectively. Approximately 16,800 child years were protected and 74 child deaths averted at an estimated cost of US $8.8 per child year protected and US $2003 per death averted. In this rural community, where life expectancy at the mean age of death of trial children was 57.5 years, the estimated cost per discounted healthy life-year gained was US $73.5. Sensitivity analysis suggested that this cost-effectiveness ratio might be reduced substantially by feasible changes in programme implementation. This study supports the argument that the cost-effectiveness of bednet impregnation is sufficiently attractive to make it part of a package of high priority interventions for children. Issues of how to finance the provision of nets and insecticide, and especially the relative contribution of governments, households and donors, need urgently to be addressed.     

The changing nature of adolescence in the Kassena-Nankana District of northern Ghana

This study reports the results of a primarily qualitative investigation of adolescent reproductive behavior in the Kassena-Nankana District, an isolated rural area in northern Ghana, where traditional patterns of marriage, family formation, and social organization persist. The study is based on in-depth interviews and focus-group discussions with adolescents, parents, chiefs, traditional leaders, youth leaders, and health workers, supplemented by quantitative data from the 1996 wave of a panel survey of women of reproductive age conducted by the Navrongo Health Research Centre. The social environment that adolescent boys and girls in the Kassena-Nankana District encounter and its links to reproductive behavior are described. The principal question is whether even in this remote rural area, the social environment has been altered in ways that have undermined traditional sexual and reproductive patterns. The survey data indicate a considerable increase in girls' education and the beginning of a decline in the incidence of early marriage. The qualitative data suggest that social institutions, systems, and practices such as female circumcision that previously structured the lives of adolescent boys and girls have eroded, leading to an apparent increase in premarital sexual activity.     

Frequency measurements in real-time US equipment: variations from expected values

The frequency responses of nine real-time mechanical probes and two pulsed Doppler probes from four manufacturers were measured. The reflected frequency was measured in a clinical environment by evaluating the pulser, transducer assembly, and receiver as a system. Two independent systems were used for these measurements: a spectrum analyzer and a data acquisition system that computed the fast Fourier transform of the reflected waveform. Results showed that probe frequency (calibrated by the manufacturer in the transmit mode with a hydrophone) was as much as 30% higher than that found by means of frequency measurement procedures with the probe attached to the ultrasound system and evaluated in the receive mode. Such large discrepancies indicate that if acceptance testing of the frequency spectrum is not performed at a clinical facility, prolonged clinical evaluation of new equipment should be arranged.