The landscape configuration of zoonotic transmission of Ebola virus disease in West and Central Africa: interaction between population density and vegetation cover

Ebola virus disease (EVD) is an emerging infectious disease of zoonotic origin that has been responsible for high mortality and significant social disruption in West and Central Africa. Zoonotic transmission of EVD requires contact between susceptible human hosts and the reservoir species for Ebolaviruses, which are believed to be fruit bats. Nevertheless, features of the landscape that may facilitate such points of contact have not yet been adequately identified. Nor have spatial dependencies between zoonotic EVD transmission and landscape structures been delineated. This investigation sought to describe the spatial relationship between zoonotic EVD transmission events, or spillovers, and population density and vegetation cover. An inhomogeneous Poisson process model was fitted to all precisely geolocated zoonotic transmissions of EVD in West and Central Africa. Population density was strongly associated with spillover; however, there was significant interaction between population density and green vegetation cover. In areas of very low population density, increasing vegetation cover was associated with a decrease in risk of zoonotic transmission, but as population density increased in a given area, increasing vegetation cover was associated with increased risk of zoonotic transmission. This study showed that the spatial dependencies of Ebolavirus spillover were associated with the distribution of population density and vegetation cover in the landscape, even after controlling for climate and altitude. While this is an observational study, and thus precludes direct causal inference, the findings do highlight areas that may be at risk for zoonotic EVD transmission based on the spatial configuration of important features of the landscape.

Rat sightings in New York City are associated with neighborhood sociodemographics, housing characteristics, and proximity to open public space

Rats are ubiquitous in urban environments and, as established reservoirs for infectious pathogens, present a control priority for public health agencies. New York City (NYC) harbors one of the largest rat populations in the United States, but surprising little study has been undertaken to define rat ecology across varied features of this urban landscape. More importantly, factors that may contribute to increased encounters between rats and humans have rarely been explored. Using city-wide records of rat sightings reported to the NYC Department of Health and Mental Hygiene, this investigation sought to identify sociodemographic, housing, and physical landscape characteristics that are associated with increased rat sightings across NYC census tracts. A hierarchical Bayesian conditional autoregressive Poisson model was used to assess these associations while accounting for spatial heterogeneity in the variance. Closer proximity to both subway lines and recreational public spaces was associated with a higher concentration of rat sightings, as was a greater presence of older housing, vacant housing units, and low education among the population. Moreover, these aspects of the physical and social landscape accurately predicted rat sightings across the city. These findings have identified specific features of the NYC urban environment that may help to provide direct control targets for reducing human–rat encounters.

Forest fragmentation and risk of giardiasis in New York State

In the United States, giardiasis is endemic in northern and northeastern states, but its ecology and epidemiology remain elusive. The underlying physical landscape may play a role in shaping points of contact between humans, animals, and Giardia cysts. This study examined 11 years of surveillance data in New York State to measure the relationship between forest fragmentation and the incidence of giardiasis. Adjusted Poisson models showed that increasing points of contact between forested land and developed land, as measured by their shared edges [incident rate ratio (IRR) = 1.003; P < 0.001] and by the perimeter length of forested patches (IRR = 1.31; P = 0.01), were associated with higher incidence of giardiasis cases, whereas increasing forest density was associated with a lower incidence (IRR = 0.97; P < 0.001). These associations were independent of both temperature and surface water area. While these results are only suggestive due to the county-level aggregated data, the findings do identify a potentially important signal in the landscape epidemiology of giardiasis and highlight the need for better, more targeted, field studies on individual water sources for household consumption, inter-species contact in ecotones, surface water contamination, and human giardiasis cases.

Using magnetic resonance imaging to determine preoperative autograft sizes in anterior cruciate ligament reconstruction

PURPOSE

Accurate prediction of autograft size for anterior cruciate ligament reconstruction can assist in preoperative planning and decision-making regarding graft choices. This study seeks to determine the accuracy of MRI measurements by comparing intraoperative measurements of the patella, semitendinosis, and gracilis tendons while correlating these measurements with patient anthropometric data such as gender, height, and weight.

METHODS

A series of 20 consecutive patients were enrolled who underwent a magnetic resonance imaging study of the knee and proceeded with surgical reconstruction of the anterior cruciate ligament. Intraoperative measurements of the diameter of semitendinosis and gracilis tendons or width of patella tendon were compared to radiographic measurements obtained on the MRI. These measurements were analyzed using a paired t-test as well as regression analysis to evaluate strength of correlation between measurements and also to determine correlation with height, weight, and gender.

RESULTS

There was no statistical difference between intraoperative and radiographic measurements (p > 0.05). There was strong correlation (Pearson r = 0.98, p = 0.00) found between intraoperative and radiographic measurements of the autograft tendons. Weaker correlation was seen with gender, height, and weight with intraoperative measurements.

CONCLUSIONS

Measuring the diameter of the semitendinosis and gracilis tendons and patellar width on MRI can give an accurate prediction of actual intraoperative sizes of these anatomic structures. Height, weight, and gender were also correlated with tendon sizes implying that a patient of female gender or of smaller stature in height or weight may have smaller tendon sizes. Routine use of preoperative MRI measurements can guide surgeons with specific graft preferences to other surgical options if the graft is measured to be insufficient in size.

Toxocara infection and diminished lung function in a nationally representative sample from the United States population

The relevance of parasitic infection for the increasing incidence of asthma is a topic of considerable debate. Large population-based studies examining the association between helminth infection and specific measures of lung function in humans are lacking. This report sought to examine this association by exploring the differences in forced expiratory volume in 1s (FEV(1)) among participants with and without infection with Toxocara spp. using data from the Third National Health and Nutrition Examination Survey, undertaken by the United States Department of Health and Human Services, during 1988-1994. The results showed a significant association between diminished lung function and previous infection with Toxocara spp. Those with antibody evidence of Toxocara infection displayed FEV(1) that was 105.3mL less than those without previous infection. This relationship persisted while controlling for age, sex, education level, BMI, smoking status, ethnicity, immigration, rural residence and dog ownership (fully-adjusted difference=73mL). These findings suggest diminished lung function in the presence of Toxocara infection and illustrate the urgent need for longitudinal data to more clearly define the immunological relationship with helminth infection and its potential influence on lung function.

Sex and race characteristics in patients undergoing hip and knee arthroplasty in an urban setting

The purpose of this study was to examine the relationship between sex, race, and preoperative function in a large diverse patient population undergoing hip and knee arthroplasty. An observational study was conducted on 3542 consecutive primary unilateral total hip and knee arthroplasties. Harris Hip and Knee Society Scores were used to quantify preoperative function. The results demonstrate lower function, with average Harris Hip Scores that were 4.9 (P < .0001) and 8.77 (P < .001) and average Knee Society Scores that were 6.03 (P < .06) and 12.8 (P < .001) points lower in African American and Hispanic patients than white patients for the population, respectively. This study demonstrates that Hispanic and African American patients have worse preoperative hip and knee function before arthroplasty than white patients. Future efforts to elucidate the reasons for this decreased function as well as efforts to rectify any disparities should target these patient populations.

Invited commentary: a fine balance--weighing risk factors against risk

Fracture is a leading cause of disability in the aging population. Because the cost of fracture in terms of medical expenditures and quality of life lost can be substantial, it is essential to identify a complete profile of fracture risk for the development of timely interventions. Risk factors for fracture have most often been identified clinically. Thus, the contribution by Wagner et al. in this issue of the Journal is particularly important, since it demonstrates a robust association between balance impairment and fracture in a population-based setting. It is unclear, however, whether isolating balance as a risk factor can tell us enough about the clustering of risk factors for fracture that accompanies frailty. Indeed, this problem of risk clustering is one that epidemiologists often encounter as we try to locate the mediating processes between exposures and outcomes that lead downstream through complex interacting causal pathways. In this commentary, the author discusses the importance, particularly when studying frailty and fracture, of quantifying risk clustering rather than continuing to rely on solitary risk factors. Moreover, the author suggests the use of Bayesian networks in the expansion of our tool kit in this field of research.

A multinational assessment of complications in type 1 diabetes: the DiaMond substudy of complications (DiaComp) level 1

The objectives of this study were to describe the global geographic variation of microvascular and macrovascular complications in childhood onset type 1 diabetes (T1D) and to relate any such variation to diabetes care activities such as self blood glucose monitoring and intensive insulin therapy. The DiaComp study is a multinational (17 countries) cross-sectional study of complications in T1D (n=2,657). All participants were diagnosed at < 15 years of age and had a diabetes duration of 5-24 years when surveyed. Complications were assessed by self-report of physician diagnosis. Twenty-two centres in 17 countries achieved at least a 67% response rate and are included in the analyses. Central European centres exhibited high rates of retinopathy (Lithuania=31.6%, Romania=24.2%), laser treatment (Lithuania=25.4%) and neuropathy (Lithuania=29.9%, Romania=12.4%) in those with short duration of diabetes (5-15 years), as did Cuba for neuropathy (15.4%). For retinopathy the geographic variation in the short-duration group was also pronounced, ranging from 1.6% in Italy to 41.6% in Lithuania, and from 0% in Brazil, Italy and Australia, to 29.9% in Lithuania for laser treatment. Variation was less dramatic for the prevalence of complications in the long-duration group (15-25 years). Hypertension and duration were strong consistent predictors of all complications, while women had higher prevalence for half the complications (retinopathy, laser treatment and renal disease). Intensive insulin therapy and self-monitoring of blood glucose showed little association with prevalence of complications. In conclusion, this first population-based account of the geographic variation of T1D complications has demonstrated substantial variation. However, the healthcare practice variables that were measured contributed little toward explaining this variation.

Spinal injuries in Irish rugby: a ten-year review

This study assessed the frequency of acute injury to the spinal cord in Irish Rugby over a period of ten years, between 1995 and 2004. There were 12 such injuries; 11 were cervical and one was thoracic. Ten occurred in adults and two in schoolboys. All were males playing Rugby Union and the mean age at injury was 21.6 years (16 to 36). The most common mechanism of injury was hyperflexion of the cervical spine and the players injured most frequently were playing at full back, hooker or on the wing. Most injuries were sustained during the tackle phase of play. Six players felt their injury was preventable. Eight are permanently disabled as a result of their injury.

Predictors of short-term functional outcome following ankle fracture surgery

BACKGROUND

Ankle fractures are among the most common injuries treated by orthopaedic surgeons. However, very few investigators have examined the functional recovery following ankle fracture surgery and, to our knowledge, none have analyzed factors that may predict functional recovery. In this study, we evaluated predictors of short-term functional outcome following surgical stabilization of ankle fractures.

METHODS

Over three years, 232 patients who sustained a fracture of the ankle and were treated surgically were followed prospectively, for a minimum of one year. Trained interviewers recorded baseline characteristics, including patient demographics, medical comorbidities, and functional status according to the Short Musculoskeletal Function Assessment (SMFA). Laboratory findings, the American Society of Anesthesiologists (ASA) class, and operative findings were recorded from the chart during hospitalization. Follow-up information included the occurrence of complications or additional surgery, weight-bearing status, functional status according to the SMFA, and the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot score. The data were analyzed to determine predictors of functional recovery at three months, six months, and one year postoperatively.

RESULTS

Complete follow-up data were available for 198 patients (85%). At one year, 174 (88%) of the patients had either no or mild ankle pain and 178 (90%) had either no limitations or limitations only in recreational activities. According to the AOFAS ankle-hindfoot score, 178 (90%) of the patients had > or = 90% functional recovery. A patient age of less than forty years was a predictor of recovery, as measured with the SMFA subscores, at six months after the ankle fracture. At one year, however, age was no longer a predictor of recovery. Patients who were younger than forty were more likely to recover > or = 90% of function (p = 0.004), and men were more likely than women to recover function (p = 0.02). ASA Class 1 or 2 (p = 0.03) and an absence of diabetes (p = 0.02) were also predictors of better functional recovery at one year. SMFA subscores were below average at baseline, indicating a healthy population. At three and six months postoperatively, all SMFA subscores were significantly higher than the baseline subscores (p < 0.001); however, at one year, the SMFA subscores were almost back to the baseline, normal level.

CONCLUSIONS

One year after ankle fracture surgery, patients are generally doing well, with most experiencing little or mild pain and few restrictions in functional activities. They have a significant improvement in function compared with six months after the surgery. Younger age, male sex, absence of diabetes, and a lower ASA class are predictive of functional recovery at one year following ankle fracture surgery. It is important to counsel patients and their families regarding the expected functional recovery after an ankle injury.

The socioeconomic correlates of global complication prevalence in type 1 diabetes (T1D): a multinational comparison

We sought to determine the extent to which the geographic variation in the complications of type 1 diabetes (T1D) may reflect the socioeconomic status (SES) conditions and health care performance (HCP) of countries around the world. The World Health Organization (WHO) DiaMond complications study (DiaComp) is a multinational, cross-sectional study of complications in T1D. Information on complications was identified for 892 subjects from 14 clinical centers in 12 countries. All participants were diagnosed with diabetes in childhood (<15 years of age) and had disease duration of 5-24 years. Complications were assessed by self-report, and by clinical exam, with microalbuminuria identified by Micral II dipstick, neuropathy by the Michigan Neuropathy Screening Instrument exam and hypertension using the HDFP protocol. These data were linked to center-specific information on the local social and economic landscape, health care access and diabetes management practices and health care costs. Country-specific indicators of social and economic development were also linked to the complications data. Both diabetes complications and economic and health care factors vary widely across the DiaComp centers. Health system performance, as measured by disability adjusted life expectancy (DALE), gross national investment (GNI) per capita and purchasing power all showed strong consistent correlations with complications, and significant independent associations with complication prevalence after controlling for HbA1c and hypertension. In conclusion, health system performance, social distribution of wealth and purchasing power may play important roles in explaining the geographic variation of diabetes complications.

A multinational comparison of complications assessment in type 1 diabetes: the DiaMond substudy of complications (DiaComp) level 2

OBJECTIVE

To describe the global geographic variation of micro- and macrovascular complications in childhood-onset type 1 diabetes assessed by both reported and measured disease and risk factors and relate any such variation to diabetes control and health care activities.

RESEARCH DESIGN AND METHODS

The DiaComp study is a multinational (17 countries) cross-sectional study of complications in type 1 diabetes and is comprised of two levels (level 1 includes survey only and level 2 includes survey plus examination). This report concerns level 2, representing 12 countries (n = 892). All participants were diagnosed at <15 years of age and had a diabetes duration of 5-24 years when surveyed. All complications were assessed by self-report and for microalbuminuria by Micral II dipstick, neuropathy by the Michigan Neuropathy Screening Instrument exam, and hypertension using the Hypertension Detection and Follow-up Program (HDFP) protocol. HbA(1c) was determined by using the DCA analyzer.

RESULTS

A wide variation in neuropathy, reported renal disease/proteinuria, and hypertension among those of short diabetes duration was noted, with central Europe (Romania and Lithuania) standing out for both self-reported renal disease and measured microalbuminuria and for both self-reported and examined neuropathy. The Caribbean (Puerto Rico) also had high rates of microalbuminuria and examined neuropathy. For those of long duration, variation was more moderate. We found generally good agreement between the reported and clinically determined measures for neuropathy (r = 0.5, P = 0.01) and hypertension (r = 0.61, P = 0.001) as demonstrated by the high overall correlation between examination and self-report for these two complications. However, the agreement between examination and self-report for renal disease/proteinuria was less, with low overall correlation (r = -0.05, P = 0.86) and incongruous centers (Slovakia and Finland). Geographic variation in prevalence was not consistently explained for all complications, even with strong independent prediction by systolic blood pressure, although the variation in microalbuminuria was largely accounted for by self-monitored blood glucose, which was significantly protective.

CONCLUSIONS

This report has identified wide variation and geographic patterns in complication prevalence, with a further indication that self-report is generally in agreement with examined prevalence, though less for renal disease/proteinuria. However, this level of DiaComp, with more complete assessment of risk factors and health care practice, was still not able to completely explain the variation in complication prevalence, except for microalbuminuria.

Human nucleus pulposis can respond to a pro-inflammatory stimulus

STUDY DESIGN

Disc tissue obtained from patients undergoing surgery for scoliosis, lumbar radiculopathy, and discogenic pain was cultured under basal and lipopolysaccharide-stimulated conditions and the medium analyzed for production of a range of pro-inflammatory mediators.

OBJECTIVES

This study was conducted to confirm that the human intervertebral disc is capable of responding to a pro-inflammatory stimulus and to identify the principal mediators involved in any response.

SUMMARY OF BACKGROUND DATA

Degenerate human disc tissue has been shown to spontaneously secrete a number of pro-inflammatory mediators. The importance of these molecules in the pathophysiology of symptomatic disc degeneration is increasingly recognized. Human nucleus pulposus has been shown to synthesize increased amounts of interleukin (IL)-6, prostaglandin E2 (PGE2), and nitric oxide in response to stimulation with IL-1beta. Murine nucleus pulposus synthesizes increased amounts of IL-1beta, IL-6, IL-10, and granulocyte-macrophage colony-stimulating factor in response to lipopolysaccharide stimulation. Lipopolysaccharide is a potent inducer of tumor necrosis factor-alpha (TNF-alpha), which is thought to play an important role in the pathophysiology of sciatica. To date, human nucleus pulposus has not been shown to secrete TNF-alpha in response to a pro-inflammatory stimulus.

METHODS

Human disc tissue obtained from patients undergoing surgery for scoliosis, lumbar radiculopathy, and discogenic pain was cultured under basal and lipopolysaccharide-stimulated conditions and the medium subsequently analyzed for a range of pro-inflammatory mediators.

RESULTS

None of the specimens produced any TNF-alpha, IL-1beta, granulocyte-macrophage colony-stimulating factor, or leukotriene B4. Measurable quantities of IL-6, IL-8, PGE2, MCP-1, basic fibroblast growth factor, and trans forming growth factor-beta1 were produced by a number of specimens. Lipopolysaccharide significantly increased IL-6, IL-8, and PGE2 production in both control and degenerate disc tissue. Degenerate disc specimens responded more vigorously to lipopolysaccharide stimulation than scoliotic specimens.

CONCLUSIONS

We conclude that both scoliotic and degenerate human nucleus pulposus can respond to an exogenous pro-inflammatory stimulus by secreting increased amounts of IL-6, IL-8, and PGE2 but not TNF-alpha and that degenerate disc tissue is more sensitive to a pro-inflammatory stimulus than its scoliotic counterpart.

Lumbar Chance fracture associated with use of the lap belt restraint in an adolescent

The use of the 2-point seat belt or lap belt in motor vehicles, particularly to restrain young rear seat passengers, remains an issue of some concern. The occurrence of lumbar spinal flexion-distraction injuries in lap belt restrained children and adolescents during road traffic accidents is a well known phenomenon, but is still occurring. High velocity paediatric Chance fractures are frequently associated with significant intra-abdominal trauma. We present the case of a Chance fracture sustained by a 15 year old girl, involved in a motor vehicle collision, while wearing a lap belt. We emphasise the need to develop safer seat belt designs for juvenile car passengers.

Recognition of progressive atlanto-occipital dislocation (by a changing neurologic status and clinical deformity)

We present a case of progressive atlanto-occipital dislocation, recognized by a new onset of positive neurologic findings. We discuss the anatomic relationship of the lower four cranial nerves to the foramen magnum and the atlanto-occipital joint. The importance of careful assessment of the cranial nerves prior to choosing a treatment algorithm is emphasized.

Intervertebral discs which cause low back pain secrete high levels of proinflammatory mediators

Herniated intervertebral disc tissue has been shown to produce a number of proinflammatory mediators and cytokines, but there have been no similar studies using discs from patients with discogenic low back pain. We have compared the levels of production of interleukin-6 (IL-6), interleukin-8 (IL-8) and prostaglandin E2 (PGE2) in disc tissue from patients undergoing discectomy for sciatica (63) with that from patients undergoing fusion for discogenic low back pain (20) using an enzyme-linked immunoabsorbent assay. There was a statistically significant difference between levels of production of IL-6 and IL-8 in the sciatica and low back pain groups (p < 0.006 and p < 0.003, respectively). The high levels of proinflammatory mediator found in disc tissue from patients undergoing fusion suggest that production of proinflammatory mediators within the nucleus pulposus may be a major factor in the genesis of a painful lumbar disc.

Short-term benefit of arthroscopic washout in degenerative arthritis of the knee

Over a 4-year period, 55 consecutive knee arthroscopies were performed on 54 patients with symptomatic mild to moderate osteoarthritis. There were 30 female patients and the average patient age was 60.9 years. The average follow-up period was 29.6 months. All patients underwent diagnostic arthroscopy and washout. Further procedures including removal of loose bodies and partial meniscal resection were necessary in 19 patients. There were no significant postoperative complications. Thirty-seven patients had subjective improvement in symptoms. The average duration of benefit was 25.5 months. Arthroscopy and appropriate debridement of the degenerative knee results in significant subjective improvement. This relatively minor procedure can delay or indeed obviate the need for reconstructive surgery.

Evaluation of the syndesmotic screw in low Weber C ankle fractures

OBJECTIVE

To determine the functional and radiographic outcome of low Weber C ankle fractures and to evaluate the contribution of the syndesmotic screw in their outcome.

DESIGN

Prospective evaluation of a consecutive series.

SETTING

Level I trauma center.

PATIENTS

Forty-five patients divided into two groups matched for age, sex, and severity of injury. Twenty-six patients were treated with open reduction, internal fixation, and a supplemental syndesmotic screw, and nineteen patients were treated without a syndesmotic screw. Minimum time to follow-up was three years.

METHODS

A subjective, objective, and radiographic ankle scoring system was used. Logistical regression analysis was performed to determine whether the presence or absence of a syndesmotic screw was a predictor of a poor outcome. The likelihood ratio test was used to evaluate the significance of each variable in both univariate and multivariate analyses.

RESULTS

There was no statistically significant difference between either group, either using subjective outcome criteria (p = 0.86) or in ankle range of motion (p = 0.94). Logistical regression analysis indicated that fracture dislocation could be used as a predictor of a poor outcome for either group. Inadequate reduction and advancing age were also found to be significant predictors of a poorer outcome regardless of the use of a syndesmotic screw (p = 0.003, p = 0.004).

CONCLUSIONS

Judicious fixation of Weber C type injuries within five centimeters of the ankle joint, with or without a syndesmotic screw, gives similar results. Obligatory fixation of these fractures with syndesmotic screws appears to have no benefit and creates the need for an additional procedure.

Damage to the superior gluteal nerve after two different approaches to the hip

We have carried out a blind, prospective study of 50 consecutive patients undergoing replacement arthroplasty of the hip using two different approaches. Clinical assessment, including the Harris hip score and a modified Trendelenberg test, and electrophysiological examination of the abductor muscles of the hip were undertaken before and three months after surgery. We found that 48% of patients had preoperative evidence of chronic injury to the superior gluteal nerve. Perioperative injury to the nerve occurred commonly with both approaches to the hip. We did not find a significant correlation between injury to the superior gluteal nerve and clinical problems.

Predictors of outcome in cauda equina syndrome

This retrospective review examined the cause, level of pathology, onset of symptoms, time taken to treatment, and outcome of 19 patients with cauda equina syndrome (CES). The minimum time to follow up was 22 months. Logistical regression analysis was used to determine how these factors influenced the eventual outcome. Out of 19 patients, 14 had satisfactory recovery at 2 years post-decompression; 5 patients were left with some residual dysfunction. The mean time to decompression in the group with a satisfactory outcome was 14 h (range 6-24 h) whilst that of the group with the poor outcome was 30 h (range 20-72 h). There was a clear correlation between delayed decompression and a poor outcome (P = 0.023). Saddle hypoaesthesia was evident in all patients. In addition complete perineal anaesthesia was evident in 7/19 patients, 5 of whom developed a poor outcome. Bladder dysfunction was observed in 19/19 patients, with 12/19 regarded as having significant impairment. Of the five patients identified as having a poor overall outcome, all five presented with a significant sphincter disturbance and 4/5 were left with residual sphincter dysfunction. There was a clear correlation between the presence of complete perineal anaesthesia and significant sphincter dysfunction as both univariate and multivariate predictors of a poor overall outcome. The association between a slower onset of CES and a more favourable outcome did not reach statistical significance (P = 0.052). No correlation could be found between initial motor function loss, bilateral sciatica, level or cause of injury as predictors of a poor outcome (P>0.05). CES can be diagnosed early by judicious physical examination, with particular attention to perineal sensation and a history of urinary dysfunction. The most important factors identified in this series as predictors of a favourable outcome in CES were early diagnosis and early decompression.