Malaria and low Birth Weigh in Central Sudan

* This paper was published in the American Journal of Epidemiology Vol.138, No.5 Cpoyright©1993 by The Johns Hopkins University School of Hygiene and Public Health. All rights reserved. A nested case-control hospital study and a midwife-based community cohort study were conducted in central Sudan during 1989 and 1990 to assess the contribution of mesoendemic malaria to low birth weight. Malarial infection was determined by maternal history, parasitology, and histopathology. There were significant associations between a maternal history of malaria and low birth weight in the hospital study (adjusted odds ratio (OR)=1.6,95% confidence interval (CI)1.2-2.1) and the community study (OR=1.7,95%CI 1.3-2-3). Attributable risk percentages were high and were com- parable in the hospital study (22.2%) and the community study (24.5%) a significant trend of increased risk of low brith weight was observed with increasing number of report malaria attacks, with attacks occurring earlier in pregnancy, and with higher parasitemia. In addition, the risk of low birth weight associated with malaria was higher among primiparous women than among multiparous women. The mean birth weight of infants whose mothers had malaria during pregnancy was significantly lower than the mean birth weight of whose mothers did not. Malaria treatment, chemoprophy- laxis, and use of insectiones decreased the risk of low birth weight and are recom- mended as appropriate interventions. These measures should target primigravid women and should be initiated early in pregnancy. Am J Epidemiol 1993;138:318-25. Infant, low weight; malaria; parasitology; pregnancy outcom

Parametric frailty models for clustered data with arbitrary censoring: application to effect of male circumcision on HPV clearance

Background In epidemiological studies, subjects are often followed for a period during which study outcomes are measured at selected time points, such as by diagnostic testing performed on biological samples collected at each visit. Although test results may indicate the presence or absence of a disease or condition, they cannot provide information on when exactly it occurred. Such study designs generate arbitrarily censored time-to-event data, which can include left, interval and right censoring. Adding to this complexity, the data may be clustered such that observations within the same cluster are not independent, such as time to recovery of an infectious disease of family or community members. This data structure is observed when evaluating circumcision\u27s effect on clearance of penile high risk human papillomavirus (HR-HPV) infections using data collected from the male circumcision(MC) trial conducted in Rakai, Uganda, where the multiple infections within individual and HPV testings performed at trial follow-up visits gave rise to the clustered data with arbitrary censoring. Methods We describe the use of parametric proportional hazards frailty models and accelerated failure time frailty models to examine the relationship between explanatory variables and the survival outcomes that are subject to arbitrary censoring, while accounting for the correlation within clusters. Standard software such as SAS can be used for parameter estimation. Results Circumcision\u27s effect on HPV infection was a secondary end point in the Rakai MC trial, and HPV genotyping was conducted for penile samples of a subset of trial participants collected at enrollment, 6, 12 and 24-month follow up visits. At enrollment, 36.7% intervention arm men (immediate circumcision) and 36.6% control arm men (delayed circumcision at 2 years) were infected with HR-HPV, with the number of infections per man being 1-5. The proposed models were used to examine whether MC facilitated clearance of the prevalent infections. Results show that clearance of multiple infections within each man is highly correlated, and clearance was 60% faster if a man was circumcised. Conclusions Parametric frailty models provide viable ways to study the relationship between exposure variables and clustered survival outcome that is subject to arbitrary censoring, as is often observed in HPV epidemiology studies

The determinants of use of maternal and child health services in Metro Cebu, the Philippines

The determinants of the use of family planning, prenatal care, childhood immunizations and oral rehydration salts (ORS) were studied with survey data of 8000 women in Metro Cebu, the Philippines. Polytomous logistic regression methods were used. The level of maternal education was the most consistent and important determinant of use of these four health services in both urban and rural areas. For example, the estimated odds of using modern contraception increased by six and eleven per cent for each additional year of schooling in urban and rural strata respectively. Economic status and access to service variables had less consistent patterns: women’s work status, for example, was associated only with contraceptive use

Impact experiments into multiple-mesh targets: Concept development of a lightweight collisional bumper

The utility of multiple-mesh targets as potential lightweight shields to protect spacecraft in low-Earth orbit against collisional damage is explored. Earlier studies revealed that single meshes comminute hypervelocity impactors with efficiencies comparable to contiguous targets. Multiple interaction of projectile fragments with any number of meshes should lead to increased comminution, deceleration, and dispersion of the projectile, such that all debris exiting the mesh stack possesses low specific energies (ergs/sq cm) that would readily be tolerated by many flight systems. The study is conceptually exploring the sensitivity of major variables such as impact velocity, the specific areal mass (g/sq cm) of the total mesh stack (SM), and the separation distance (S) between individual meshes. Most experiments employed five or ten meshes with total SM typically less than 0.5 the specific mass of the impactor, and silicate glass impactors rather than metal projectiles. While projectile comminution increases with increasing impact velocity due to progressively higher shock stresses, encounters with multiple-meshes at low velocity (1-2 km/s) already lead to significant disruption of the glass impactors, with the resulting fragments being additionally decelerated and dispersed by subsequent meshes, and, unlike most contiguous single-plate bumpers, leading to respectable performance at low velocity. Total specific bumper mass must be the subject of careful trade-off studies; relatively massive bumpers will generate too much debris being dislodged from the bumper itself, while exceptionally lightweight designs will not cause sufficient comminution, deceleration, or dispersion of the impactor. Separation distance was found to be a crucial design parameter, as it controls the dispersion of the fragment cloud. Substantial mass savings could result if maximum separation distances were employed. The total mass of debris dislodged by multiple-mesh stacks is modestly smaller than that of single, contiguous-membrane shields. The cumulative surface area of all penetration holes in multiple mesh stacks is an order of magnitude smaller than that in analog multiple-foil shields, suggesting good long-term performance of the mesh designs. Due to different experimental conditions, direct and quantitative comparison with other lightweight shields is not possible at present

Peripheral neuropathy in HIV-infected and uninfected patients in Rakai, Uganda

OBJECTIVE: To determine the prevalence, risk factors, and functional impairment associated with peripheral neuropathy in a prospective cohort of adults in rural Uganda. METHODS: Eight hundred participants (400 HIV- and 400 antiretroviral-naive HIV+) in the Rakai Community Cohort Study underwent detailed neurologic evaluations including assessment of neuropathy symptoms, functional measures (Patient Assessment of Own Functioning Inventory and Karnofsky Performance Status scores), and neurologic evaluation by a trained medical officer. Neuropathy was defined as ≥1 subjective symptom and ≥1 sign of neuropathy on examination. Neuropathy risk factors were assessed using log binomial regression. RESULTS: Fifty-three percent of participants were men, with a mean (SD) age of 35 (8) years. Neuropathy was present in 13% of the cohort and was more common in HIV+ vs HIV- participants (19% vs 7%, p < 0.001). Older age (relative risk [RR] 1.04, 95% confidence interval [CI] 1.02-1.06), female sex (RR 1.49, 95% CI 1.04-2.15), HIV infection (RR 2.82, 95% CI 1.86-4.28), tobacco use (RR 1.59, 95% CI 1.02-2.48), and prior neurotoxic medication use (RR 2.08, 95% CI 1.07-4.05) were significant predictors of neuropathy in the overall cohort. Only older age was associated with neuropathy risk in the HIV+ (RR 1.03, 95% CI 1.01-1.05) and HIV- (RR 1.06, 95% CI 1.02-1.10) cohorts. Neuropathy was associated with impaired functional status on multiple measures across all participant groups. CONCLUSIONS: Peripheral neuropathy is relatively common and associated with impaired functional status among adults in rural Uganda. Older age, female sex, and HIV infection significantly increase the risk of neuropathy. Neuropathy may be an underrecognized but important condition in rural Uganda and warrants further study

The Strong Protective Effect of Circumcision against Cancer of the Penis

Male circumcision protects against cancer of the penis, the invasive form of which is a devastating disease confined almost exclusively to uncircumcised men. Major etiological factors are phimosis, balanitis, and high-risk types of human papillomavirus (HPV), which are more prevalent in the glans penis and coronal sulcus covered by the foreskin, as well as on the penile shaft, of uncircumcised men. Circumcised men clear HPV infections more quickly. Phimosis (a constricted foreskin opening impeding the passage of urine) is confined to uncircumcised men, in whom balanitis (affecting 10%) is more common than in circumcised men. Each is strongly associated with risk of penile cancer. These findings have led to calls for promotion of male circumcision, especially in infancy, to help reduce the global burden of penile cancer. Even more relevant globally is protection from cervical cancer, which is 10-times more common, being much higher in women with uncircumcised male partners. Male circumcision also provides indirect protection against various other infections in women, along with direct protection for men from a number of genital tract infections, including HIV. Given that adverse consequences of medical male circumcision, especially when performed in infancy, are rare, this simple prophylactic procedure should be promoted

HIV infection in rural households, Rakai district, Uganda

The Rakai Project conducted a population-based cohort study in rural Rakai District, Uganda, a region with high rates of HIV prevalence. The cohort population described here was followed between 1990 and 1992 and consisted of all residents aged 15 years or more living in 1945 households in 31 community clusters. A detailed census was conducted at baseline in every study household. Census data were updated annually, and all inter-survey deaths, births, and migrations were recorded. Immediately following each annual census, all consenting adults were administered a socio-demographic, behavioural and health survey, and provided a blood sample for HIV testing. HIV prevalence in the study population was high, with 19.1 per cent of adults aged 15 or more years being HIV-positive. By household, the burden of infection was even more pronounced: 31.3 per cent of households had at least one HIV-infected resident adult. Twenty seven per cent of heads of households were also HIV-positive. Overall, 3.6 per cent of study households experienced the death of an HIV-positive adult per year, and another two per cent lost an HIV-negative adult. HIV-related adult mortality had substantially more effect on subsequent household dependency ratio and on material possessions than the death of an HIV-uninfected adult, in part because the former deaths were concentrated in adults aged 15-49, the most economically active age group in this rural population. Just under 15 per cent of children aged 14 years or less had lost one or both parents, and approximately half of these parental losses are estimated to be associated with HIV infection. Nineteen per cent of study households reported at least one resident child who had lost one or both parents. Although there is evidence that loss of a parent is associated with lower school attendance, orphans overall continue to be absorbed by community households which are headed by adults. HIV infection is very prevalent among adults in Rakai and the associated mortality imposes a substantial social and economic burden on households in the district

Generation of broadband terahertz radiation using a backward wave oscillator and pseudospark-sourced electron beam

This paper presents for the generation of a small size high current density pseudospark (PS) electron beam for a high frequency (0.2 THz) Backward Wave Oscillator (BWO) through a Doppler up-shift of the plasma frequency. An electron beam ∼1 mm diameter carrying a current of up to 10 A and current density of 1E8 Am&#x100000;2, with a sweeping voltage of 42 to 25 kV and pulse duration of 25 ns was generated from the PS discharge. This beam propagated through the rippled-wall slow wave structure of a BWO beam-wave interaction region in a plasma environment without the need for a guiding magnetic field. Plasma wave assisted beam-wave interaction resulted in broadband output over a frequency range of 186 - 202 GHz with a maximum power of 20 W