In silico Mechanics of Stem Cells Intramyocardially Transplanted with a Biomaterial Injectate for Treatment of Myocardial Infarction.

PURPOSE: Biomaterial and stem cell delivery are promising approaches to treating myocardial infarction. However, the mechanical and biochemical mechanisms underlying the therapeutic benefits require further clarification. This study aimed to assess the deformation of stem cells injected with the biomaterial into the infarcted heart. METHODS: A microstructural finite element model of a mid-wall infarcted myocardial region was developed from ex vivo microcomputed tomography data of a rat heart with left ventricular infarct and intramyocardial biomaterial injectate. Nine cells were numerically seeded in the injectate of the microstructural model. The microstructural and a previously developed biventricular finite element model of the same rat heart were used to quantify the deformation of the cells during a cardiac cycle for a biomaterial elastic modulus (Einj) ranging between 4.1 and 405,900 kPa. RESULTS: The transplanted cells' deformation was largest for Einj = 7.4 kPa, matching that of the cells, and decreased for an increase and decrease in Einj. The cell deformation was more sensitive to Einj changes for softer (Einj ≤ 738 kPa) than stiffer biomaterials. CONCLUSIONS: Combining the microstructural and biventricular finite element models enables quantifying micromechanics of transplanted cells in the heart. The approach offers a broader scope for in silico investigations of biomaterial and cell therapies for myocardial infarction and other cardiac pathologies.

Effect of biomaterial stiffness on cardiac mechanics in a biventricular infarcted rat heart model with microstructural representation of in situ intramyocardial injectate.

Intramyocardial delivery of biomaterials is a promising concept for treating myocardial infarction. The delivered biomaterial provides mechanical support and attenuates wall thinning and elevated wall stress in the infarct region. This study aimed at developing a biventricular finite element model of an infarcted rat heart with a microstructural representation of an in situ biomaterial injectate, and a parametric investigation of the effect of the injectate stiffness on the cardiac mechanics. A three-dimensional subject-specific biventricular finite element model of a rat heart with left ventricular infarct and microstructurally dispersed biomaterial delivered 1 week after infarct induction was developed from ex vivo microcomputed tomography data. The volumetric mesh density varied between 303 mm-3 in the myocardium and 3852 mm-3 in the injectate region due to the microstructural intramyocardial dispersion. Parametric simulations were conducted with the injectate's elastic modulus varying from 4.1 to 405,900 kPa, and myocardial and injectate strains were recorded. With increasing injectate stiffness, the end-diastolic median myocardial fibre and cross-fibre strain decreased in magnitude from 3.6% to 1.1% and from -6.0% to -2.9%, respectively. At end-systole, the myocardial fibre and cross-fibre strain decreased in magnitude from -20.4% to -11.8% and from 6.5% to 4.6%, respectively. In the injectate, the maximum and minimum principal strains decreased in magnitude from 5.4% to 0.001% and from -5.4% to -0.001%, respectively, at end-diastole and from 38.5% to 0.06% and from -39.0% to -0.06%, respectively, at end-systole. With the microstructural injectate geometry, the developed subject-specific cardiac finite element model offers potential for extension to cellular injectates and in silico studies of mechanotransduction and therapeutic signalling in the infarcted heart with an infarct animal model extensively used in preclinical research.

Evaluation of a real-time multiplex PCR for the simultaneous detection of Campylobacter jejuni, Salmonella spp., Shigella spp./EIEC, and Yersinia enterocolitica in fecal samples.

Conventional diagnosis of infectious diarrhea caused by bacteria is time-consuming, labor-intensive, and has a suboptimal sensitivity. We have therefore developed a multiplex real-time polymerase chain reaction (PCR) for the simultaneous detection of Campylobacter jejuni, Salmonella spp., Shigella spp./enteroinvasive Escherichia coli (EIEC), and Yersinia enterocolitica in fecal samples. No cross reactivity between the different pathogens was observed, and the multiplex setup of the assay did not have an impact on the sensitivity of the PCR. The analytical sensitivity was 87 CFU/mL for C. jejuni, 61 CFU/mL for Shigella spp./EIEC, 5,528 CFU/mL for Salmonella spp., and 1,306 CFU/mL for Y. enterocolitica. An extensive validation of the assay was performed by testing 1,687 patient samples by both PCR and with conventional techniques. The use of PCR increased the overall clinical sensitivity from 78 to 100 % (p < 0.0001), the specificity was 99.4 % for the PCR, compared with 99.9 % for conventional culture. The novel PCR assay allows for rapid, sensitive, inexpensive, and high-throughput testing of the most common bacterial causes of gastroenteritis.

Illness incidence and health seeking behaviour among street children in Rawalpindi and Islamabad, Pakistan - a qualitative study.

BACKGROUND: This is the first study in Pakistan to elicit street children's perceptions of health and the barriers to service utilization. METHODS: A descriptive, cross-sectional study was carried out during September and October 2000. The data were collected in twin-cities of Rawalpindi and Islamabad through individual, semi-structured street-based interviews; with 40 school age participants; in addition, three focus group discussions were also completed. The sampling was convenience based. This strategy was applied because of the non-existence of a sampling frame for the street-based children owing to the absence of any census or other reports, and also the difficulty of tracking very mobile street children. RESULTS: Results indicate that these youth were highly susceptible to many adverse health outcomes. The common ailments were injuries, respiratory and skin infections. Along with low self-perceived severity of medical problems, self-medication was preferred and medical pluralism existed. Their perceived constraints to services included long waiting time, monetary, negative attitude of service providers and their inferior status. CONCLUSIONS: In developing user-friendly services, it is important to be sensitive to street children's needs and requirements. Eliminating these barriers and the integration of health services among public and private resources are imperative for the regular and sustainable provision of health care to this vulnerable, under-served group of children.

The limits to patient compliance with directly observed therapy for tuberculosis: a socio-medical study in Pakistan.

Complying with the prescriptions of the directly observed therapy (DOT), one of the components of the Global Tuberculosis Programme of the WHO, is problematic for many patients. The factors leading to patient (non-) compliance with DOT are placed in a structural equation model. The study is based on a survey carried out in one general hospital in the Punjab province of Pakistan, amongst all sputum positive pulmonary TB patients (n = 621) who arrived at the TB unit from September 1997 to October 1998. The tested sequence of manifest variables and latent constructs shows that the social stratification perspective has to be extended by the stigmatization perspective. The advantages of universally applying DOT will increase even further when the latter perspective is involved in the analysis of non-compliance. There is a real danger that the patients reached by selective DOT will be stigmatized even more.

Microbiology and risk factors for catheter exit-site and -hub colonization in neonatal intensive care unit patients.

OBJECTIVE: To identify risk factors and describe the microbiology of catheter exit-site and hub colonization in neonates. DESIGN: During a period of 2 years, we prospectively investigated 14 risk factors for catheter exit-site and hub colonization in 862 central venous catheters in a cohort of 441 neonates. Cultures of the catheter exit-site and hub were obtained using semiquantitative techniques at time of catheter removal. SETTING: A neonatal intensive care unit at a university hospital. RESULTS: Catheter exit-site colonization was found in 7.2% and hub colonization in 5.3%. Coagulase-negative staphylococci were predominant at both sites. Pathogenic flora were found more frequently at the catheter hub (36% vs 14%; P<.05). Through logistic regression, factors associated with exit-site colonization were identified as umbilical insertion (odds ratio [OR], 8.1; 95% confidence interval [CI95], 2.35-27.6; P<.001), subclavian insertion (OR, 54.6; CI95, 12.2-244, P<.001), and colonization of the catheter hub (OR, 8.9; CI, 3.5-22.8; P<.001). Catheter-hub colonization was associated with total parenteral nutrition ([TPN] OR for each day of TPN, 1.056; CI95, 1.029-1.083; P<.001) and catheter exit-site colonization (OR, 6.11; CI95, 2.603-14.34; P<.001). No association was found between colonization at these sites and duration of catheterization and venue of insertion, physician's experience, postnatal age and patient's weight, ventilation, steroids or antibiotics, and catheter repositioning. CONCLUSION: These data support that colonization of the catheter exit-site is associated with the site of insertion and colonization of the catheter hub with the use of TPN. There is a very strong association between colonization at both catheter sites.

Risk factors for central vascular catheter-associated bloodstream infections among patients in a neonatal intensive care unit.

The aim of this study was to identify risk factors for catheter-associated bloodstream infection (CABSI) in neonates. We undertook a prospective investigation of the potential risk factors for CABSI (patient-related, treatment-related and catheter-related) in a neonatal intensive care unit (NICU) using univariate and multivariate techniques. We also investigated the relationship between catheter hub and catheter exit site colonization with CABSI.Thirty-five episodes of CABSI occurred in 862 central catheters over a period of 8028 catheter-days, with a cumulative incidence of 4.1/100 catheters and an incidence density of 4.4/1000 catheter days. Factors independently associated with CABSI were: catheter hub colonization (odds ratio [OR] = 44.1, 95% confidence interval [CI] = 14.5 to 134.4), exit site colonization (OR = 14.4, CI = 4.8 to 42.6), extremely low weight (< 1000 g) at time of catheter insertion (OR = 5.13, CI = 2.1 to 12.5), duration of parenteral nutrition (OR=1.04, CI=1.0 to 1.08) and catheter insertion after first week of life (OR = 2.7, CI = 1.1 to 6.7). In 15 (43%) out of the 35 CABSI episodes the catheter hub was colonized, in nine (26%) cases the catheter exit site was colonized and in three (9%) cases colonization was found at both sites. This prospective cohort study on CABSI in a NICU identified five risk factors of which two can be used for risk-stratified incidence density description (birthweight and time of catheter insertion). It also emphasized the importance of catheter exit site, hub colonization and exposure to parenteral nutrition in the pathogenesis of CABSI.

Catheter manipulations and the risk of catheter-associated bloodstream infection in neonatal intensive care unit patients.

A prospective cohort study was performed to evaluate the influence of catheter manipulations on catheter associated bloodstream infection (CABSI) in neonates. Neonates admitted between 1 November 1993 and 31 October 1994 at the neonatal intensive care unit of a university hospital were included in the study. Seventeen episodes of CABSI occurred in 357 central catheters over a period of 3470 catheter-days, with a cumulative incidence of 4.7/100 catheters and an incidence density of 4.9/1000 catheter-days. Patient and catheter-related risk factors independently associated with CABSI were: catheter hub colonization (odds ratio [OR] = 32.6, 95% confidence interval [95% CI] = 4.3-249), extremely low weight (

Prediction of nosocomial sepsis in neonates by means of a computer-weighted bedside scoring system (NOSEP score)

OBJECTIVE: To develop an easy-to-use bedside scoring system, composed of clinical variables, hematologic variables, and risk factors of infection, to predict nosocomial sepsis in neonatal intensive care unit patients. SETTING: A neonatal intensive care unit in a university hospital, Antwerp, Belgium. PATIENTS: Over 2 yrs, we analyzed two groups of patients. First, we prospectively studied 104 episodes of presumed nosocomial sepsis in 80 neonates (derivation cohort), and then we retrospectively studied 50 episodes in 39 neonates (validation cohort). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We developed two versions of a scoring system to predict nosocomial sepsis in sick neonates. The first scoring system (NOSEP-1 score) was based on 15 clinical, 12 laboratory, and 17 historical variables potentially connected with infection; the second one (NOSEP-2 score) also included the culture results of central vascular catheters. Based on the odds ratios of all independent variables, an additive and weighted score was developed and validated in a cohort of 39 patients screened for nosocomial sepsis in the same center. The NOSEP-1 score consisted of three laboratory variables (C-reactive protein > or =14 mg/L, thrombocytopenia <150 x 10(9)/L, and neutrophil fraction >50%), one clinical factor (fever >38.2 degrees C [100.8 degrees F]), and one risk factor (parenteral nutrition for > or =14 days). The NOSEP-2 score consisted of the same variables plus catheter-hub and catheter insertion site colonization data. Receiver operating characteristic curve analysis demonstrated good predictor performance of the NOSEP-1 score (area under the curve [Az] = 0.82 +/- 0.04 [SEM]) and NOSEP-2 score (Az = 0.84 +/- 0.04, p < .05). We checked whether a complex computer-generated scoring system (CD-1 and CD-2 scores) based on the original numerical values of the items used in NOSEP-1 and NOSEP-2 would improve the prediction of nosocomial sepsis. The analysis showed the accuracy of bedside NOSEP-1 and NOSEP-2 scores to be comparable with the more cumbersome computer-generated CD-1 and CD-2 scores (receiver operating characteristic curve, Az: CD-1 score = 0.81 +/- 0.04, p = .69, and CD-2 score = 0.86 +/- 0.04, p = .96). Finally, in the validation cohort, we showed that the developed scoring system has a good prediction potential for nosocomial sepsis (Hosmer-Lemeshow goodness-of-fit test, chi2 [19] = 16.34, p > .75). CONCLUSIONS: The simple bedside scoring system NOSEP-1 composed of C-reactive protein, neutrophil fraction, thrombocytopenia, fever, and prolonged parenteral nutrition exposure provides a valuable tool for early identification of nosocomial sepsis. Its predictive power can be improved by adding central vascular catheter insertion site and hub colonization to the score.

A randomised trial of the impact of counselling on treatment adherence of tuberculosis patients in Sialkot, Pakistan.

SETTING: Tuberculosis Department, Bethania Hospital, Sialkot, Pakistan. OBJECTIVE: To determine whether intensive counselling can improve treatment adherence. DESIGN: In a randomised controlled intervention trial of 1,019 adult tuberculosis patients, 49% were assigned to the intervention group and 51% to the control group. Baseline data were obtained through semi-structured interviews. Patients were followed until the end of treatment (cure, default, referral or death). The intervention included counselling at the start of treatment and at each subsequent visit for ambulatory patients, or weekly for hospitalised patients. Counselling combined health education with strategies to strengthen patients' self-efficacy. Control group patients received the usual care. The outcome measure was treatment default. RESULTS: The default rate was 54% in the control group and 47% in the intervention group: the default risk ratio was 0.87, implying a reduction in defaulting of 13%. The impact was stronger in women, ambulatory patients, re-treatment patients, women who worked in the home, and patients who were not the main provider, those with a poor knowledge of the disease or those with a short treatment delay. CONCLUSIONS: Intensive counselling has a significant, although limited, impact on treatment adherence.

Multi-centre evaluation of repeatability and reproducibility of the direct agglutination test for visceral leishmaniasis.

OBJECTIVE: To evaluate the repeatability and reproducibility of the serological direct agglutination test (DAT) for visceral leishmaniasis (VL) with aqueous antigen in a multi-centre study in VL-endemic areas in Sudan, Kenya and Nepal. METHODS: Repeatability within each centre and reproducibility between the centres' results and an external reference laboratory (Belgium) was assessed on 1596 triplicate plain blood samples collected on filter paper. RESULTS: High kappa values (range 0.86-0.97) indicated excellent DAT repeatability within the centres. The means of the titre differences between the reference laboratory and the centres in Sudan, Kenya and Nepal (2.3, 2.4 and 1.1, respectively, all significantly different from 0) showed weak reproducibility across centres. 95% of the titre differences between the reference laboratory and the respective centres were accounted for by large intervals: 0.6-9 fold titre variation for Sudan, 0.7-8 fold for Kenya and 0.26-4 fold for Nepal. CONCLUSION: High repeatability of DAT confirms its potential, but reproducibility problems remain an obstacle to its routine use in the field. Reproducibility was hindered by alteration of the antigen through temperature and shaking, especially in Kenya and Sudan, and by nonstandardization of the test reading. DAT handling procedures and antigen quality must be carefully standardized and monitored when introducing this test into routine practice.

Operational validation of the direct agglutination test for diagnosis of visceral leishmaniasis.

The validity of the direct agglutination test (DAT) for visceral leishmaniasis (VL) was studied with a standardized field kit on 148 clinically suspected persons and 176 healthy controls recruited between 1993 and 1994 from an endemic area in Gedaref State, Sudan. A sensitivity of 95.9% and a specificity of 99.4% were found at a 1: 8,000 cut-off titer when parasitologically confirmed cases were compared with healthy controls. While corroborating previously reported sensitivity and specificity estimates of this serodiagnostic test, this study examined the bias generated by commonly used test validation procedures. The fundamental methodologic problem in VL test validation is the absence of a reliable gold standard. Moreover, any operational guideline on DAT use has to consider the critical dependency of the predictive values of the test on VL prevalence rates. The DAT diagnostic cut-off titer depends upon many external factors, among which the prevalence of disease in the area and the case mix seem the most important.

[Study of the factors determining an unexpected occurrecne of Chagas cardiomyopathy in Sucre, Bolivia]. / Etude des facteurs determinant la survenue d'une myocardiopathie chagasique a Sucre, Bolivie.

The purpose of this case-control study carried out between February 1, 1994 and December 22, 1994 at the "Instituto de Gastroenterologia Boliviano-Japonés" in Sucre, Bolivia was to determine risk factors for chronic Chagas cardiomyopathy in adult patients with positive serological tests for Trypanosoma cruzi. A total of 196 subjects were included. Inclusion criteria were positive serological tests for Trypanosoma cruzi, residence in the city of Sucre, Bolivia for at least 3 months, and age over 14 years. There were 62 cases presenting electrocardiographic findings consistent with Chagas cardiomyopathy and 134 controls presenting normal electrocardiographic findings. Both cases and controls underwent a standardized protocol including physical examination and laboratory tests. Interviews were set up to evaluate personal and familial history of Chagas disease, socioeconomic status, and presence of Triatoma infestans in the home. Bivariate analysis of data indicated that Chagas cardiomyopathy was associated with the following risk factors: heart rate (p < 0.05), fecaloma (p < 0.05), occupation requiring strenuous physical exertion (p < 0.001), proximity with domestic animals (p < 0.005), especially pigs (p < 0.005), dwelling features including outbuildings, more than 2 bedrooms, and inside ceilings (p < 0.001). Multivariate analysis revealed the following risk factors: occupation requiring strenuous physical exertion (p < 0.005), a yard around the house (p < 0.05), and inside ceilings (p < 0.05). The results of this study show that prevention of chronic Chagas cardiomyopathy in Sucre, Bolivia will depend on improvement of living conditions.

[Schistosoma intercalatum bilharziasis: clinical and epidemiological considerations]. / La bilharziose à Schistosoma intercalatum: considèrations cliniques et èpidèmiologiques.

Schistosoma intercalatum bilharziasis continues to raise numerous questions regarding pathogenicity and gravity. The parasite was identified recently and the last fully described outbreak occurred 10 years ago in the city of Bata, Equatorial Guinea. Geographically Schistosoma intercalatum biharziasis is limited to one part of the African continent but has shown a tendency to spread. Hybridization of Schistosoma intercalatum and Schistosoma haematobium has been observed. The main clinical manifestation of Schistosoma intercalatum is rectal bleeding. The endoscopic appearance of lesions is variable and non-specific ranging from granulomas or polyps to ulcerations. Complications include severe rectitis or genital involvement such as salpingitis with secondary sterility. Spontaneous abortion has also been reported. Association with salmonella and klebsiella infection has been confirmed and can lead to life-threatening situations. Few studies have been performed to assess the value of diagnostic tests. The sensitivity of stool smears and urinary sedimentation testing is 81.7% and 56.3% respectively using the two examinations as references for one another. The sensitivity of immunological tests is generally good but varies depending on the reference technique used. Specificity can be affected by cross-reaction with other schistosomas or trematodes and even with nematodes and hematozoons. Treatment with a single dose of Biltricide has proven to be effective. Prevention requires education of the population at risk and use of molluscacides. The control strategy must be adapted in function of the epidemiology of the disease, diagnostic data, cost and effectiveness of screening and treatment.

[Historical aspects of the risk factors of Schistosoma intercalatum schistosomiasis]. / Historique des facteurs de risque de la bilharziose à Schistosoma intercalatum.

Bilharziosis is a considerable public health problem. It is caused by many species of schistosoma, four of which have wide geographical distribution: Schistosoma mansoni, S. haematobium, S. japonicum and S. intercalatum. The recently discovered S. intercalatum is limited to central and west Africa. Its spread is progressive and its pathogenicity is not completely known. S. intercalatum bilharziosis is usually manifested in the form of dysentery. The physiopathologic explanation of this clinical manifestation is less clear. Immunopathologically, the formation of an inflammatory granuloma constitutes the origin of its symptoms. This is due to many biological factors including delayed hypersensitivity reactions. All cellular immunity changes will facilitate the appearance of symptoms. Our aim has been to show the importance of malnutrition as a pathogenic factor of S. intercalatum bilharziosis. The initial research hypothesis was as follows: malnutrition plays a role in the evolution of a patient from an asymptomatic state of infection to a symptomatic state of illness. We carried out the study in the suburbs of Bata, in Equatorial Guinea. The inhabitants of Ncolombong, essentially rural immigrants, comprised our study population. Following their consent, we recruited individuals less than 45 years of age who had not taken praziquantel during the last 12 months. We included a total of 297 patients. Our study was a case-control, matching on sex and age. A case was defined as an infected patient with acute or chronic diarrhea occurring within the last month' preceding the stool sample analysis. All cases were retained after exhaustive screening of the study population. Each case (group 1) was matched with one or several asymptomatic infected patients (group 2) and two or several asymptomatic noninfected patients chosen at random (group 3). The definition of malnutrition was as follows: weight/height < or = 90% for children less than 15 years of age or weight/height < or = 90% with a corporal mass index < or = 20 for children more than 15 years of age. Two logistical regression models were performed in order to distinguish pathogenic from infection factors. Among the confusion bias identified, none of the helminthiasis in Bata are risk factors. The risk factors of the infection have been searched with an interrogatory. The bias caused by the interviewer is minimized because all the team staff were trained for a week before the beginning of the study. Apart from malnutrition, the other causes of cellular immunodeficiency do not seem to have any relationship with the development of symptoms. The logistical model of infection identified the classical risk factors of infection: river leisures (OR = 3.97, CI 95%: 1.86-8.47), poor or average quality of walls of the house (OR = 2.53, CI 95%: 1.15-5.58), lack of water well (OR = 2.08, CI 95%: 1.08-4). Our study could not show any relationship between malnutrition and bilharziosis. The nutritional state does not play a significative role in the infection or development of the disease. Nevertheless, the nutritional state of the host probably influences other host or parasite factors. As a result, we still don't know its influence on ADCC (Antibody Dependent Cellular Mediated Cytotoxicity) mechanisms, on adult parasite adaptation and the efficiency of laying of eggs which affects the parasitological charge. We haven't found any relationship between parasitological load and appearance of symptoms. The parasitological load indirectly reflects the efficiency of the laying and nothing proves that it is correlated with the intensity of delayed type hypersensibility reactions. In the logistical model of the disease, a stay of more than 2 months in an endemic area (OR = 0.14, CI 95%: 0.03-0.76) and a poor or average quality of walls of the house decreased the risk (OR = 0.31, CI 95%: 0.11-0.85). This result permits us to suppose that there is a tolerance to schistosomian antigens by cellular immunity

[Evaluation of the Ivory Coast sentinel surveillance system for antimalarial drug sensitivity]. / Evaluation du systéme ivoirien de survelliance sentinelle de la chimosensibilité des antipaludiques.

This study was performed to assess the sentinel surveillance system on malaria resistance in Cote d'Ivoire using a new method. Evaluation was based on documentation describing routine products and on activity reports obtained from the surveillance system. A qualitative approach was used to assess system design and quantitative approach to assess its operation. Degree of satisfaction with evaluation criteria was scored on a scale of 1 to 5. Score reproducibility in this study was good. Overall the system was considered as satisfactory. The strong points of the system are relevance, functions, sustainability, and data quality. The weak points are poor planning, overcentralization, and underuse of information. Correction of these weakness will require concentration by all parties at the national level involved in the surveillance system. The evaluation method used was simple, cheap and reproducible and thus could serve as an alternative approach for evaluation of sentinel surveillance systems in areas with scarce resources.

[Contribution of a mathematical model in the control of a parasitosis: the case of human African trypanosomiasis due to Trypanosoma brucei gambiense]. / Apport d'un modèle mathématique dans le contrôle d'une parasitose: cas de la trypanosomiase humaine africaine à Trypanosoma brucei gambiense.

Trypanosoma brucei gambiense sleeping sickness transmitted by tsetse flies (Glossina spp.) is lethal if not treated adequately. The endemicity was generally well under control in the sixties. However, since the seventies the disease is returning in most of its old foci, with alarming endemic levels in several areas. Mathematical modelling provides a rational basis for finding the optimal strategies to control these recrudescences. We present a deterministic model of the basic transmission of trypanosomiasis between human and vector hosts in natural situations. The parameters were quantified on the basis of available evidence from the literature. The model predicts a stable equilibrium state with very high prevalences: approximately 95% of humans and 27% of flies being infected. The model further shows that the build-up of an epidemic is initially very slow, and it takes several months before the equilibrium state is reached. Consequently communities have enough time to avoid catastrophic situations by migrating to safer areas. If is therefore unlikely that such high equilibrium situations will occur in practice. The expression of the basic reproductive rate R0, the number of new infections during the lifetime of an infected subject with high values of R0 implies that efforts to diminish transmission to levels where the disease cannot maintain itself in the population, have to be substantial. The necessary reduction of fly numbers in order to enable eradication, has been calculated. In almost all situations a reduction of at least 90% is necessary, which is in accordance with the field experiences of vector control programmes. The present model can be considered as a starting point in the further development of a complete simulation model, which could be applied in supporting decision making in trypanosomiasis control.

Perception and social consequences of tuberculosis: a focus group study of tuberculosis patients in Sialkot, Pakistan.

Treatment defaulting is one of the major causes of the failure of TB control programs. In Bethania Hospital, Sialkot, defaulting rates are high: 72% for the standard 12 months course and 56% for the 8 months course. Attrition is especially important in the first weeks of treatment: < 70% of the patients start the 10th week of treatment. A focus group discussion study has been carried out to gain a better understanding of the impact of social stigmatization, treatment cost and pregnancy on defaulting. The study population consisted of 3 male and 3 female groups each with 8 hospitalized TB patients. The study shows that TB is perceived as a very dangerous, infectious and incurable disease. This perception has many social consequences: stigmatization and social isolation of TB patients and their families: diminished marriage prospects for young TB patients, and even for their family members: TB in one of the partners may lead to divorce. Due to fear patients often deny the diagnosis and reject the treatment. While both male and female TB patients face many social and economical problems, female patients are more affected. Divorce and broken engagements seem to occur more often in female patients. Females are usually economically dependent on their husbands and family in law, and need their cooperation to avail of treatment. The belief that pregnancy enhances the risk for relapse decreases their marriage prospects. Pregnancy is also a reason for stopping TB treatment as both are considered as incompatible. The findings of this study reveal the urgent need for a health education campaign to convince the general population that tuberculosis is curable. All health care providers should act as destigmatizers.

Human immunodeficiency virus infection and human African trypanosomiasis: a case-control study in Côte d'Ivoire.

To assess the association between human immunodeficiency virus (HIV) infection and human African trypanosomiasis (HAT) in Côte d'Ivoire, West Africa, a cross-sectional case-control study was conducted on 301 HAT patients recruited in the main foci of the country. For each HAT patient, 3 controls, matched for sex, age and residence, were selected. Data relating to socio-demographic factors and potential risk factors for Trypanosoma brucei gambiense and HIV infections were obtained, and serum samples were collected for HIV-1 and HIV-2 tests. A positive test consisted of enzyme immunoassay reactive to HIV-1, HIV-2 or both and confirmed by a synthetic peptide test or Western blot. Data were analyzed using conditional logistic regression with EGRET software. No statistically significant difference was found between the prevalence of HIV infection in HAT patients and controls (4.3% and 3.5% respectively; crude odds ratio (OR) 1.28, 95% confidence interval (CI) 0.65-2.50). In multivariate analysis, allowance for 5 covariates did not change the association between the 2 infections (adjusted OR 1.27, 95% CI 0.64-2.52). Although this study had limited statistical power, no significant association was found between HIV infection and T.b. gambiense infection in rural Côte d'Ivoire. Studies are needed to determine whether HIV infection influences the clinical course of HAT, a question not addressed in the present study.