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Biomedical subjects

Davidson H Hamer

Publications and source records attributed to Davidson H Hamer.

At least 19 recordsLinked to original sources
PubMed2006

Travel-related health problems of Hong Kong residents: Assessing the need for travel medicine services.

BACKGROUND: Although there has been a marked increase in travel among Hong Kong residents, travel-related health risks have not been well characterized nor has their use of travel medicine services. OBJECTIVES: To assess the travel health care needs of Chinese residents in Hong Kong by examining travel health problems of returning Hong Kong residents and by understanding their use of travel health services before or after travel. METHODS: Review of available data followed by a cross-sectional telephone survey of 280 travellers and 15 service providers. A structured pre-tested questionnaire was used for data collection. Household members, who were ethnic Chinese, aged 15-64 years, able to communicate in Cantonese, and who had travelled at least once during the preceding 12 months were invited to participate. RESULTS: There was a scarcity of travel medicine services in Hong Kong. The most common destinations for travellers were countries in the Asia-Pacific region, especially mainland China (33%). Twenty percent of the respondents developed health problems during or shortly after travel. Although only 9% of respondents had received pre-travel health advice, 61% used some form of precautions. Twelve percent had lost at least a day due to travel-related health problems. The service providers agreed that there are demands for travel health services. However, half of the service providers had not been trained in travel or tropical medicine. CONCLUSIONS: This study indicates the need for specialized travel medicine services in Hong Kong to improve the health of travellers.

Adolescent↗
PubMed2006

Nutritional, immunological and health status of the elderly population living in poor neighbourhoods of Quito, Ecuador.

The number of elderly people is increasing in less-developed countries. Although nutritional deficiencies and infectious diseases are generally more prevalent in resource-poor countries, the health and nutritional status of the elderly in South America in general, and in Ecuador, in particular, remains largely unstudied. The objective of the present study was to assess the nutritional, immunological and health status of elderly Ecuadorians. A cross-sectional study was conducted to evaluate a sample of elderly Ecuadorians with 24 h dietary recalls, biochemical and anthropometric measurements, delayed type hypersensitivity skin response and a health questionnaire. The 145 elders who enrolled had a mean age of 74.3 (SD 6.9) years. Of the subjects, 52 % exhibited BMI >or=25 kg/m(2), whereas 9.1 % had BMI <or=20 kg/m(2). Means of dietary intakes were below recommendations for most nutrients; exceptions were carbohydrate, fat, Fe and Se. Serum nutrient levels indicated that 50, 44, 43, 19 and 18 % of participants had deficiencies of Zn, Fe, vitamins B12 and D, and folate, respectively. The mean number of positive responses to seven recall antigens was 2.1 (SD 1.7) with an induration diameter of 9.9 (SD 7) mm, which are substantially lower than those reported for elders in developed countries. During the previous 6 months, 54 and 21 % of subjects reported at least one episode of respiratory infection or diarrhoea, respectively. Of these, 47 % sought care at a hospital or from a physician and 96 % from a relative or friend. In conclusion, while few elderly Ecuadorians were underweight, obesity was common. Micronutrient deficiencies were prevalent and may contribute to reduced immunological responses in this population.

Aged↗
PubMed2005

Treatment of paediatric malaria during a period of drug transition to artemether-lumefantrine in Zambia: cross sectional study.

OBJECTIVE: To evaluate treatment practices for uncomplicated malaria after the policy change from chloroquine to sulfadoxine-pyrimethamine and to artemether-lumefantrine in Zambia. DESIGN: Cross sectional survey. SETTING: Outpatient departments of all government and mission facilities in four districts in Zambia. PARTICIPANTS: 944 children with uncomplicated malaria seen by 103 health workers at 94 health facilities. MAIN OUTCOME MEASURES: Antimalarial prescriptions in accordance with national guidelines and influence of factors on health workers' decision to prescribe artemether-lumefantrine. RESULTS: Artemether-lumefantrine, sulfadoxine-pyrimethamine, and chloroquine were available, respectively, at 48 (51%), 94 (100%), and 71 (76%) of the 94 facilities. Of 944 children with uncomplicated malaria, only one child (0.1%) received chloroquine. Among children weighing less than 10 kg, sulfadoxine-pyrimethamine was commonly prescribed in accordance with guidelines (439/550, 79.8%). Among the children weighing 10 kg or more, sulfadoxine-pyrimethamine was commonly prescribed (266/394, 68%), whereas recommended artemether-lumefantrine was prescribed for only 42/394 (11%) children. Among children weighing 10 kg or more seen at facilities where artemether-lumefantrine was available, the same pattern was observed: artemether-lumefantrine was prescribed for only 42/192 (22%) children and sulfadoxine-pyrimethamine remained the drug of choice (103/192, 54%). Programmatic activities such as in-service training and provision of job aids did not seem to influence the prescribing of artemether with lumefantrine. CONCLUSION: Although the use of chloroquine for uncomplicated malaria was successfully discontinued in Zambia, the change of drug policy towards artemether-lumefantrine does not necessarily translate into adequate use of this drug at the point of care.

Ambulatory Care↗
PubMed2005

No room for complacency about adherence to antiretroviral therapy in sub-Saharan Africa.

Medication adherence is essential to successful treatment of HIV/AIDS. Maintaining high adherence will likely prove a major challenge in Africa -- just as it has in developed nations. Despite early reports suggesting that adherence would not pose a major barrier to treatment success, more recent research shows that adherence rates in Africa are quite variable and often poor. Given the large number of patients whose disease will progress if adherence is suboptimal, research is urgently needed to determine patient-level behavioral barriers to adherence and the most effective and appropriate methods for assessing adherence in African cohorts.

Africa South of the Sahara↗
PubMed2005

A sensitivity analysis of a randomized controlled trial of zinc in treatment of falciparum malaria in children.

BACKGROUND: The randomized trial has long been recognized as a means to assess the efficacy of new interventions, because the investigator can reduce or eliminate many sources of error. As such, clinical trials often do not include quantitative assessments of the extent that systematic error could affect their results. We examined the impact of different sources of bias on a randomized controlled trial of the efficacy of zinc as an adjuvant to malaria therapy in reducing time to total parasite clearance. METHODS: Using data from a previously published study, we identified two sources of bias and used the sensitivity analysis technique developed by Lash and Fink to assess the impact of each source of bias on the outcome. RESULTS: After correcting for each source of bias and reincorporating random error into our results, the point estimate of effect comparing those who received placebo to those who received zinc changed slightly (SMR changed from 0.92 to 0.90) but the 95% interval increased 22% (changing from 0.73-1.16 in the conventional analysis to 0.65-1.26 in the sensitivity analysis). CONCLUSIONS: The findings of this sensitivity analysis serve as a reminder that the frequentist confidence interval underestimates the total error, even in a randomized controlled trial. Authors of randomized controlled trial investigations ought to conduct a complete assessment of the impact of potential sources of bias in their studies. CONSORT guidelines for reporting trial results should be updated to encourage authors to assess the impact of non-random errors on their studies.

Antimalarials↗
PubMed2005

On the medical edge: preparation of expatriates, refugee and disaster relief workers, and Peace Corps volunteers.

Travelers to extreme environments and those who spend long periods of time in settings with limited health care resources need to have more detailed pretravel screening and education than the routine short-term traveler. Expatriates, relief workers, and Peace Corps volunteers need to receive careful pretravel medical, dental, and psychologic screening before deployment. Knowledge of special risks associated with the environment in which they will be stationed is necessary to provide effective education about ways to reduce or eliminate the risk of illness and death. The travel medicine practitioner should also provide detailed, region-specific recommendations regarding emergency care while traveling in remote regions. Information on foreign medical facilities and practitioners should be gathered in advance and regularly updated. Many fee-for-service directories of overseas medical centers are often out of date and do not include emergency contact information. Once deployed, systems should be in place to ensure the traveler's continued personal safety and maintenance of good health. Although these systems are generally beyond the scope of work of travel medicine providers, it is important for the long-term traveler to be aware of the need to be prepared to deal with unexpected medical events. In the event of an overseas emergency, the travel medicine specialist may be called on to facilitate ground or air medical evacuation to the most appropriate medical center, to communicate treatment priorities and pertinent medical details to foreign medical providers, and to facilitate international air evacuation or repatriation if necessary. In each of these cases, the experience for the patient and the travel health professional is dramatically improved by adhering to risk-reduction measures, such as pretravel screening, pretravel health and safety education, and preparing for emergencies in advance.

Altitude Sickness↗
PubMed2005

Effects of moderate doses of vitamin A as an adjunct to the treatment of pneumonia in underweight and normal-weight children: a randomized, double-blind, placebo-controlled trial.

BACKGROUND: Randomized controlled trials have shown inconsistent responses of childhood pneumonia to the use of vitamin A as an adjunct to the standard treatment of pneumonia. OBJECTIVE: We evaluated the effect of a moderate dose of vitamin A as an adjunct to standard antimicrobial treatment on the duration of respiratory signs in children with pneumonia. DESIGN: Children, aged 2-59 mo, with pneumonia and weight-for-age <50th percentile who had been admitted to the Baca Ortíz Children's Hospital in Quito, Ecuador, were randomly assigned to receive 50,000 IU (aged 2-12 mo) or 100,000 IU (aged >12-59 mo) vitamin A or a placebo. RESULTS: Of the 287 children enrolled, 145 received vitamin A and 142 received placebo. No overall differences were observed between the 2 groups in the duration of signs of pneumonia. Multiple linear regression showed a significant interaction between basal serum retinol concentration and vitamin A group for the time (in h) to remission of respiratory signs (beta = -3.57, SE = 1.09, P = 0.001). Duration of clinical signs was less in children with basal serum retinol concentrations >200 microg/L who received vitamin A supplements than in children with similar concentrations who received placebo (69.9 +/- 49.9 h compared with 131.3 +/- 143.9 h; P = 0.049). CONCLUSIONS: Overall, we found no effect of a moderate dose of vitamin A supplementation on the duration of uncomplicated pneumonia in underweight or normal-weight children aged <5 y. However, a beneficial effect was seen in children with high basal serum retinol concentrations.

Administration, Oral↗
PubMed2005

Strategies, time, and costs associated with the recruitment and enrollment of nursing home residents for a micronutrient supplementation clinical trial.

BACKGROUND: Concomitant with the substantial growth of the elderly population in the last decade, there has been a steady rise in the number of nursing home residents aged 65 years and older. Well designed, rigorously conducted clinical intervention trials provide an important source of data for evidence-based improvements in the medical care of nursing home residents. The information available on strategies for the recruitment and screening of participants for such studies in long-term care facilities, as well as the financial and time costs for carrying out these investigations, is limited. METHODS: This report describes our experience in recruiting 617 nursing home residents for a multisite, double-blind, randomized, placebo-controlled trial designed to determine the efficacy of a 1-year period of vitamin E supplementation in preventing respiratory tract infections. Comparisons of the projected staffing costs and actual costs incurred are presented, using a retrospective method for the determination of unit costs. RESULTS: Initially, 874 consents were obtained from 2815 potential participants, of which only 617 were enrolled. Each successful enrollment required an average of 15 hours of staff time at a combined personnel and supply cost of $515 per participant and a total study cost of $317,661. Several obstacles were encountered during the recruitment and enrollment process: resistance on the part of family or primary care provider; transfer out of facility; and changes in the medical condition of the patient, including death. DISCUSSION: The results of this report should prove useful to investigators developing budgets for nursing home-based clinical trials by providing a more accurate determination of the personnel needed and the costs associated with recruitment and enrollment of participants.

Clinical Trials as Topic↗
PubMed2005

Plasma zinc concentrations are depressed during the acute phase response in children with falciparum malaria.

Plasma concentrations of some micronutrients are altered in the setting of acute infectious or inflammatory stress. Previous studies have provided conflicting evidence concerning the extent and direction of changes in plasma zinc concentrations during the acute phase response. We carried out an observational cohort study in 689 children enrolled in a randomized trial of zinc supplementation during acute falciparum malaria in order to evaluate the relation between plasma zinc concentration and the acute phase response. Plasma zinc was measured by atomic absorption spectrophotometry. On admission, 70% of all subjects had low plasma zinc (<9.2 micromol/L). Multivariate analysis of predictors of admission plasma zinc showed that admission C-reactive protein (CRP), parasite density, and study site were the most important predictors. Predictors of changes in plasma zinc from admission to 72 h included baseline CRP, change in CRP, treatment group, study site, and baseline zinc concentration. In children with acute malaria infection, baseline plasma zinc concentrations were very low and were inversely correlated with CRP (r = -0.24, P < 0.0001) and the degree of parasitemia (r = -0.19, P < 0.0001). Even when CRP and time were taken into account, zinc supplementation increased plasma zinc concentration from admission to 72 h. When available, plasma zinc concentrations should be interpreted with concurrent measures of the acute phase response such as CRP. In children whose age, diet, and/or nutritional status place them at risk of zinc deficiency, those with low plasma zinc levels should be supplemented with oral zinc and followed for clinical and/or biochemical response.

Antimalarials↗
PubMed2005

Rapid diagnosis of pneumococcal meningitis: implications for treatment and measuring disease burden.

BACKGROUND: Streptococcus pneumoniae is the leading cause of childhood pneumonia and meningitis worldwide. Isolation of this organism, however, is uncommon in resource-poor countries, in part because of extensive use of prior antibiotics. A rapid, highly sensitive immunochromatographic test (ICT) for S. pneumoniae was evaluated for the diagnosis of meningitis. METHODS: Cerebrospinal fluid (CSF) from 450 children with suspected meningitis was tested with ICT, and results were compared with CSF culture, latex agglutination test (LAT) and/or polymerase chain reaction (PCR). Serial CSF specimens from 11 patients were also evaluated for duration of positive results during effective antimicrobial therapy. FINDINGS: All 122 cases of pyogenic pneumococcal meningitis positive either by culture (N = 87) or PCR (N = 35) were positive by ICT, yielding 100% (122 of 122) sensitivity. All purulent CSF specimens from patients with meningitis caused by other bacteria by culture (N = 149) or by LAT (N = 48) or those negative by culture, LAT and LytA and thus of unknown etiology (N = 20), and normal CSF specimens (N = 104) were negative by ICT. Thus the specificity of ICT also was 100% (321 of 321), although negativity of ICT was not confirmed by PCR, if it was positive for other organisms either by culture or LAT. Serotyping of S. pneumoniae strains revealed 28 different serotypes, indicating that outcome of ICT are independent of diverse capsular serotype of pneumococcus. Antigen was detected by ICT for at least 10 days after presentation, and 1 was still positive on day 20, which was longer than for either LAT or PCR. INTERPRETATION: ICT for pneumococcal antigen in CSF is 100% sensitive and specific in diagnosing pyogenic pneumococcal meningitis and can detect approximately 30% more pneumococcal meningitis cases than with culture alone. The simplicity of the test procedure and the longevity of CSF antigen detection suggest the potential utility of ICT to estimate the true burden of pneumococcal disease, as for Haemophilus influenzae type b using data from meningitis, and to guide selection of appropriate antibiotic treatment, especially in resource-poor countries with widespread prehospital antimicrobial use.

Antigens, Bacterial↗
PubMed2004

Vitamin E and respiratory tract infections in elderly nursing home residents: a randomized controlled trial.

CONTEXT: Respiratory tract infections are prevalent in elderly individuals, resulting in increased morbidity, mortality, and use of health care services. Vitamin E supplementation has been shown to improve immune response in elderly persons. However, the clinical importance of these findings has not been determined. OBJECTIVE: To determine the effect of 1 year of vitamin E supplementation on respiratory tract infections in elderly nursing home residents. DESIGN, SETTING, AND PARTICIPANTS: A randomized, double-blind, placebo-controlled trial was conducted from April 1998 to August 2001 at 33 long-term care facilities in the Boston, Mass, area. A total of 617 persons aged at least 65 years and who met the study's eligibility criteria were enrolled; 451 (73%) completed the study. INTERVENTION: Vitamin E (200 IU) or placebo capsule administered daily; all participants received a capsule containing half the recommended daily allowance of essential vitamins and minerals. MAIN OUTCOME MEASURES: Incidence of respiratory tract infections, number of persons and number of days with respiratory tract infections (upper and lower), and number of new antibiotic prescriptions for respiratory tract infections among all participants randomized and those who completed the study. RESULTS: Vitamin E had no significant effect on incidence or number of days with infection for all, upper, or lower respiratory tract infections. However, fewer participants receiving vitamin E acquired 1 or more respiratory tract infections (60% vs 68%; risk ratio [RR], 0.88; 95% confidence interval [CI], 0.76-1.00; P =.048 for all participants; and 65% vs 74%; RR, 0.88; 95% CI, 0.75-0.99; P =.04 for completing participants), or upper respiratory tract infections (44% vs 52%; RR, 0.84; 95% CI, 0.69-1.00; P =.05 for all participants; and 50% vs 62%; RR, 0.81; 95% CI, 0.66-0.96; P =.01 for completing participants). When common colds were analyzed in a post hoc subgroup analysis, the vitamin E group had a lower incidence of common cold (0.67 vs 0.81 per person-year; RR, 0.83; 95% CI, 0.68-1.01; P =.06 for all participants; and 0.66 vs 0.83 per person-year; RR, 0.80; 95% CI, 0.64-0.98; P =.04 for completing participants) and fewer participants in the vitamin E group acquired 1 or more colds (40% vs 48%; RR, 0.83; 95% CI, 0.67-1.00; P =.05 for all participants; and 46% vs 57%; RR, 0.80; 95% CI, 0.64-0.96; P =.02 for completing participants). Vitamin E had no significant effect on antibiotic use. CONCLUSIONS: Supplementation with 200 IU per day of vitamin E did not have a statistically significant effect on lower respiratory tract infections in elderly nursing home residents. However, we observed a protective effect of vitamin E supplementation on upper respiratory tract infections, particularly the common cold, that merits further investigation.

Aged↗
PubMed2004

Vitamin E and respiratory infection in the elderly.

Respiratory infections are prevalent in the elderly, resulting in increased morbidity, mortality, and utilization of health care services. Contributing to the increased incidence of infection with age is the well-described decline in immune response, which has been correlated with patterns of illness in the elderly. For example, there are higher morbidity and mortality from cancer, pneumonia, and post-operative complications in those who have diminished, delayed-type hypersensitivity skin test responses. Nutritional status is an important determinant of immune function. We have shown in double-blind, placebo-controlled trials that vitamin E supplementation significantly improved immune response, including DTH and response to vaccines. Furthermore, subjects receiving vitamin E in the 6-month trial had a 30% lower incidence of infectious diseases. That study, however, was not powered to demonstrate statistical significance, and the infections were self-reported. To overcome these limitations, we conducted a double-blind, placebo-controlled trial to determine the effect of one-year supplementation with 200 IU/day vitamin E on the incidence and duration of respiratory infections in 617 elderly nursing home residents. The results of this clinical trial show that vitamin E supplementation significantly reduces the incidence rate of common colds and the number of subjects who acquire a cold among elderly nursing home residents. A nonsignificant reduction in the duration of colds was also observed. Because of the high rate and more severe morbidity associated with common colds in this age group, these findings have important implications for the well being of the elderly as well as for the economic burden associated with their care.

Aged↗
PubMed2004

Reconsidering empirical cotrimoxazole prophylaxis for infants exposed to HIV infection.

Infants with HIV infection are vulnerable to Pneumocystis carinii pneumonia (PCP) during their first year of life. WHO and the Joint United Nations Programme on HIV/AIDS now recommend that all children of HIV-positive mothers receive prophylactic cotrimoxazole against PCP from six weeks of age and continue this therapy until exposure through breast milk ceases-and the infant is confirmed to be HIV-negative (rarely before one year of age). Empirical prophylaxis invokes a trade-off between possible benefit to the infant versus the risk of resistance to antibiotics and antimalarials. From a critical analysis of the literature, we offer a conceptual model demonstrating how, under certain circumstances, a policy of mass cotrimoxazole prophylaxis may be counterproductive.

AIDS-Related Opportunistic Infections↗
PubMed2003

Diagnostic accuracy of stool assays for inflammatory bacterial gastroenteritis in developed and resource-poor countries.

Because acute bacterial gastroenteritis is often inflammatory, rapid stool assays that detect intestinal inflammation might be used to distinguish between bacterial and nonbacterial gastroenteritis. We performed meta-analyses to determine the discriminatory power, in developed and in resource-poor countries, of rapid stool assays that test for lactoferrin, fecal leukocytes, fecal erythrocytes, and occult blood. In developed countries, the area under the summary receiver operating characteristic curve (AUC/SROC) was 0.89 for fecal leukocytes and 0.81 for occult blood. In resource-poor countries, the AUC/SROC was 0.79 for lactoferrin, 0.72 for fecal leukocytes, 0.63 for occult blood, and 0.61 for fecal erythrocytes. In developed countries, positive and negative likelihood ratios (LR+ and LR-, respectively) for fecal leukocytes were 4.56 and 0.32 when a threshold of >5 cells/high-power field was used, compared with 2.94 and 0.6 in resource-poor countries; for lactoferrin, LR+ was 1.34 and LR- was 0.17 in resource-poor countries when the threshold was an agglutination rating of "+" and a dilution of 1:50. In developing countries, rapid stool assays performed poorly, whereas in developed countries, tests for fecal leukocytes, lactoferrin, and occult blood were moderately useful and could identify patients who were more likely to benefit from empirical antibiotic therapy.

Developed Countries↗
PubMed2003

Selenium serum concentrations in malnourished Ecuadorian children: a case-control study.

Little is known about the selenium status of children living in the Andean regions of South America, which commonly have volcanic soil with low selenium content. Human selenium deficiency has been hypothesized to have a negative impact on immune function and to increase the risk of infection. The objective of this study was to evaluate the serum selenium concentrations of severely malnourished children living in urban and rural Andean Ecuador, and to compare them to a control group of normally nourished children from the same communities. Forty-three children, aged six to 36 months, with marasmus or kwashiorkor and 30 control children were enrolled from July to November 1993 in Quito, Ecuador. Serum selenium concentrations were lower in the children with marasmus (0.91 +/- 0.28 microM/L, n = 21) and kwashiorkor (0.37 +/- 0.15 microM/L, n = 22) than in those who were normally nourished (1.77 +/- 0.75 microM/L, n = 30, p < 0.001 for each difference). The serum selenium concentrations in children with kwashiorkor were significantly lower than those in children with marasmus (p < 0.001). All 22 of the children with kwashiorkor, 15 of the 21 children with marasmus, and five of the 30 normal children had serum levels < 1.08 microM/L (8.5 micrograms/dL) (chi 2 = 38.4, p < 0.00000001). In the Andean regions of Ecuador, selenium deficiency is prevalent in children with protein and caloric deficiency. Furthermore, 17% of Ecuadorian children with normal weight-for age-Z score are selenium-deficient.

Case-Control Studies↗
PubMed2002

Assessment of the Binax NOW Streptococcus pneumoniae urinary antigen test in children with nasopharyngeal pneumococcal carriage.

We evaluated the Binax NOW Streptococcus pneumoniae urinary antigen assay by testing 210 healthy children aged 2--60 months living in urban slums of Quito, Ecuador. Healthy children with nasopharyngeal carriage of S. pneumoniae were significantly more likely to have positive urinary antigen test results than were children who were not carriers (30 of 138 vs. 3 of 71 children; chi2=10.8; P<.001). The rate of nasopharyngeal carriage of S. pneumoniae decreased with increasing age; the lowest rates were found in children with the worst nutritional status.

Antigens, Bacterial↗