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Biomedical subjects

Leo G Visser

Publications and source records attributed to Leo G Visser.

11 recordsLinked to original sources
PubMed2006

Diagnostic methods for differentiation of Entamoeba histolytica and Entamoeba dispar in carriers: performance and clinical implications in a non-endemic setting.

Unpreserved faecal samples, suspected to contain Entamoeba histolytica/Entamoeba dispar cysts or trophozoites on the basis of microscopic examination, and serum samples from 416 patients were collected in a prospective study to determine whether stool antigen assays and detection of antibodies in serum are reliable methods to distinguish between carriers of E. histolytica and E. dispar in comparison to the reference test: real-time PCR. In 283 patients (68%) DNA of E. histolytica or E. dispar was amplified by real-time PCR: 6 patients with amoebic colitis (2%), 19 carriers of E. histolytica (6.7%), and 258 carriers of E. dispar (91.2%). In 133 patients (31%) no DNA of E. histolytica or E. dispar could be amplified in the stool samples. This patient group was used as control for the evaluation of diagnostic tests. Using real-time PCR as a reference test, the sensitivity and specificity of (1) the Entamoeba test for the diagnosis of E. histolytica/E. dispar carrier were 59% and 98%, (2) E. histolytica II for the diagnosis of E. histolytica carrier was 71% and 100%, and (3) serology for the diagnosis of E. histolytica infection was 83.3% and 95.2%, respectively. Applied to carriers that did not originate from an endemic country the sensitivity of serology for E. histolytica infection was 90% and specificity was 98.8%. In comparison to real-time PCR the performances of Entamoeba test and E. histolytica II lacked sensitivity for a reliable diagnosis of E. histolytica/E. dispar infection in a non-endemic setting. In carriers of E. histolytica/E. dispar from non-endemic countries the high specificity of serology can be used to establish the diagnosis of E. histolytica infection if antibodies are present.

Adolescent↗
PubMed2006

Persistent portal venous gas.

This case report describes a patient diagnosed with ongoing portal venous gas, initiated by a rather common Campylobacter enterocolitis and maintained by septic thrombophlebitis and possibly by chronic cholecystitis. Cholecystectomy attenuated the patient's septic condition. The etiology of portal venous gas determines both the patient's prognosis and the choice for either conservative or surgical treatment. This report describes persistence of portal venous gas for a long period and a possible role for chronic cholecystitis as a cause.

Campylobacter↗
PubMed2006

Lack of value of routine analysis of cerebrospinal fluid for prediction and diagnosis of external drainage-related bacterial meningitis.

OBJECT: Routine microbiological and chemical analysis of cerebrospinal fluid (CSF) is often performed to diagnose external drainage-related bacterial meningitis (ED-BM) at an early stage. A cohort study was performed to investigate the value of several commonly used CSF parameters for the prediction and diagnosis of ED-BM. METHODS: In a cohort of 230 consecutive patients in whom external drains had been placed, CSF samples were collected daily, prospectively evaluated for the presence of bacteria using Gram stain and microbiological culture, and analyzed for leukocyte count, protein concentration, glucose concentration, and ratio of CSF glucose to blood glucose. In addition, the CSF concentration of interleukin-6 (IL-6) was determined. The definition of ED-BM was based on positive culture results in combination with clinical symptoms. A matched case-control study was performed to evaluate the cohort longitudinally and to control for biasing factors such as duration of external drainage. External drainage-related bacterial meningitis developed in 22 patients (9.6%). Results from analyses of 1516 CSF samples showed no significant differences between the patients in whom ED-BM developed and a control group without ED-BM during the first 3 days of infection or during the 3 days preceding the infection with regard to leukocyte count, protein concentration, glucose concentration, and CSF/blood glucose ratio. No significant difference between groups was found for the CSF IL-6 concentration during the 3 days preceding the infection. In the matched case-control study, none of the parameters had significant predictive or diagnostic value for ED-BM in analyses using absolute values, ratios, and differences between the current and previous day's values. A comparison of the results from Gram stains and CSF cultures showed that the Gram staining had a very high specificity (99.9%) but a low sensitivity (18% [four of 22 patients] on the 1st day of infection and 60% [nine of 15 patients] on the 2nd day). CONCLUSIONS: Severe disturbances in the CSF of patients with external drains limit the value of routine CSF analysis for prediction or diagnosis of ED-BM. Routine Gram stain of CSF has also limited predictive or diagnostic value due to its low sensitivity in screening for ED-BM.

Adolescent↗
PubMed2005

Identification of typhoid fever and paratyphoid fever cases at presentation in outpatient clinics in Jakarta, Indonesia.

In Jakarta, Indonesia, over 80% of patients with typhoid fever or paratyphoid fever are treated in outpatient settings. In a community-based prospective passive surveillance study, we identified 59 typhoid, 23 paratyphoid fever and 259 non-enteric fever outpatients, all blood culture-confirmed. We compared their symptoms with the aim of developing a clinical prediction rule that may help direct empirical antibiotic treatment to cases with suspected (para)typhoid fever, rather than all febrile patients, or refer patients for additional diagnostic tests. Paratyphoid fever (Salmonella paratyphi A) could not be distinguished clinically from typhoid fever. Decisions on empirical antibiotic treatment and advice on hygiene measures in patients with suspected (para)typhoid fever should take into account chills and absence of cough in the first week of fever and delirium in the second week of illness. This prediction rule increases the likelihood of (para)typhoid fever from 1:10 in the first week to, at most, 2:3 in the second week of a febrile illness. However, we were not able to propose a robust clinical prediction rule that could be used as absolute screening method for decisions on additional diagnostic tests, because of the low sensitivity of presenting symptoms in (para)typhoid fever.

Abdominal Pain↗
PubMed2005

Bacterial meningitis caused by the use of ventricular or lumbar cerebrospinal fluid catheters.

OBJECT: In the present study the authors compared the incidence and risk factors for external drainage-related bacterial meningitis (ED-BM) by using ventricular and lumbar catheters. METHODS: A cohort of 230 consecutive patients with ED was evaluated. Cerebrospinal fluid samples were obtained daily for microbiological culture, and ED-BM was defined based on culture results in combination with clinical symptoms. The incidence of ED-BM was 7% in lumbar and 15% in ventricular drains. Independent risk factors included site leakage, drain blockage, and most importantly duration of ED. Despite a higher infection rate, ventricular catheters did not have a significant higher risk of infection after correcting for duration of drainage. CONCLUSIONS: Analysis of data in the present study showed that the incidence of ED-associated death is low (0.45%) in patients who do not receive continuous antibiotic prophylaxis during ED.

Adolescent↗
PubMed2005

A survey of the supply and bacteriologic quality of drinking water and sanitation in Jakarta, Indonesia.

We assessed the water supply, water quality and human waste disposal and their association with diarrheal illness in Jatinegara, East-Jakarta, where part of the area has been involved in the Kampung Improvement Program (KIP). Three hundred seventy-eight households, randomly selected in the study area, were visited and questioned about water source, sanitation and diarrheal illness during the previous 3 months. Microbiological quality of drinking water was assessed. The water sources were boreholes (243; 64%), the water mains (77; 20%), bottled water (45; 12%), and vendors or dug wells (243; 4%). Fecal coliforms were isolated in 56% of the samples [median 23 (IQR 6-240) /100 ml in the contaminated samples]. Only 2 (3%) of the water mains' samples contained >100 fecal coliforms/100 ml, compared to 57 (24%) groundwater samples. Most residents used private toilets with drainage into on-site septic tanks, yet in over one quarter of households human excreta was disposed of into rivers or gutters. KIP areas lagged behind in environmental hygiene. Diarrheal episodes, reported in one third of the households, were significantly associated with water contaminated with >100 fecal coliforms/100 ml [OR 2.4 (95% CI: 1.4-4.2)], but no association with water source or environmental contamination was found. Significantly, all individuals reported boiling water before consumption.

Diarrhea↗
PubMed2004

Risk factors for typhoid and paratyphoid fever in Jakarta, Indonesia.

CONTEXT: The proportion of paratyphoid fever cases to typhoid fever cases may change due to urbanization and increased dependency on food purchased from street vendors. For containment of paratyphoid a different strategy may be needed than for typhoid, because risk factors for disease may not coincide and current typhoid vaccines do not protect against paratyphoid fever. OBJECTIVE: To determine risk factors for typhoid and paratyphoid fever in an endemic area. DESIGN, SETTING, AND PARTICIPANTS: Community-based case-control study conducted from June 2001 to February 2003 in hospitals and outpatient health centers in Jatinegara district, Jakarta, Indonesia. Enrolled participants were 1019 consecutive patients with fever lasting 3 or more days, from which 69 blood culture-confirmed typhoid cases, 24 confirmed paratyphoid cases, and 289 control patients with fever but without Salmonella bacteremia were interviewed, plus 378 randomly selected community controls. MAIN OUTCOME MEASURES: Blood culture-confirmed typhoid or paratyphoid fever; risk factors for both diseases. RESULTS: In 1019 fever patients we identified 88 (9%) Salmonella typhi and 26 (3%) Salmonella paratyphi A infections. Paratyphoid fever among cases was independently associated with consumption of food from street vendors (comparison with community controls: odds ratio [OR], 3.34; 95% confidence interval [CI], 1.41-7.91; with fever controls: OR, 5.17; 95% CI, 2.12-12.60) and flooding (comparison with community controls: OR, 4.52; 95% CI, 1.90-10.73; with fever controls: OR, 3.25; 95% CI, 1.31-8.02). By contrast, independent risk factors for typhoid fever using the community control group were mostly related to the household, ie, to recent typhoid fever in the household (OR, 2.38; 95% CI, 1.03-5.48); no use of soap for handwashing (OR, 1.91; 95% CI, 1.06-3.46); sharing food from the same plate (OR, 1.93; 95% CI, 1.10-3.37), and no toilet in the household (OR, 2.20; 95% CI, 1.06-4.55). Also, typhoid fever was associated with young age in years (OR, 0.96; 95% CI, 0.94-0.98). In comparison with fever controls, risk factors for typhoid fever were use of ice cubes (OR, 2.27; 95% CI, 1.31-3.93) and female sex (OR, 1.79; 95% CI, 1.04-3.06). Fecal contamination of drinking water was not associated with typhoid or paratyphoid fever. We did not detect fecal carriers among food handlers in the households. CONCLUSIONS: In Jakarta, typhoid and paratyphoid fever are associated with distinct routes of transmission, with the risk factors for disease either mainly within the household (typhoid) or outside the household (paratyphoid).

Adolescent↗
PubMed2004

Interindividual variation in the response by fibrinogen, C-reactive protein and interleukin-6 to yellow fever vaccination.

The acute phase reaction is important in many disease processes. Habitual levels of the acute phase proteins fibrinogen, C-reactive protein (CRP) and interleukin-6 (IL-6) are associated with an increased risk of cardiovascular disease, but the dynamic variation of plasma levels of acute phase proteins may be of importance as well. The aim of this study was to document the variation in response by fibrinogen, CRP and IL-6 levels to a mild inflammatory stimulus (yellow fever vaccination) in 25 healthy individuals. Plasma levels of fibrinogen, CRP and IL-6 were determined at baseline and 7 days after vaccination, and genetic polymorphisms in these genes were determined. After vaccination, fibrinogen levels had changed between -13 and +44% (P = 0.003), CRP levels between -88 and +672% (not significant), and IL-6 levels between -55 and +448% (not significant). Genetic variation partly explained the interindividual variation in response, as IL-6 -174G homozygotes showed a significantly stronger increase in CRP levels than IL-6 -174C allele carriers. In conclusion, this study suggests that a large interindividual variation exists in the acute phase response to yellow fever vaccination, indicating that individuals may be classified as hyper-responders or hypo-responders, and that genetic variation may influence the responsiveness of an individual.

C-Reactive Protein↗
PubMed2003

Schistosomiasis does not contribute to death or recurrence of nontyphoid Salmonella bacteremia in human immunodeficiency virus-infected Malawian adults.

Nontyphoid Salmonella (NTS) bacteremia has a very high mortality and recurrence rate among human immunodeficiency virus (HIV)-infected Malawian adults. Concurrent schistosomal infection might cause persistence of NTS infection and poor response to antibiotic therapy. Therefore, we tested serum samples for Schistosoma-specific circulating anodic antigen to diagnose coinfection with schistosomiasis among consecutive HIV-positive adults with NTS bacteremia. The results suggest that active schistosomiasis is not associated with adverse outcome of NTS bacteremia in this population, in contrast to other groups.

Adult↗
PubMed2002

Yellow fever vaccination as a model to study the response to stimulation of the inflammation system.

BACKGROUND: High basal plasma levels of inflammatory molecules are associated with a higher risk of cardiovascular events. It has been suggested that also the dynamic response to an inflammatory trigger is important in determining cardiovascular risk. The aim of the present study was to evaluate the use of vaccination against yellow fever as an in vivo model to study the interindividual variation in the response to inflammatory triggers. METHODS: Ten healthy volunteers were vaccinated with 17D yellow fever vaccine. Blood samples were drawn each day, until Day 8 after vaccination. Automated blood cell counting was performed, and the plasma concentrations of C-reactive protein (CRP), interleukin-6 (IL-6) and fibrinogen were determined. RESULTS: In most individuals, CRP levels peaked slightly (45% increase from basal values) around Day 7 after vaccination, preceded by an IL-6 (30%) peak around Day 5. Fibrinogen levels showed a significant increase (10%) from Day 2 after vaccination, with a further rise (17%) around Day 5. The monocyte fraction showed a significant 2-fold increase on Day 7 after vaccination. The lymphocyte fraction increased slightly towards Day 7 (not significant). CONCLUSION: Our findings show that yellow fever vaccination can be used as a model to study the response to mild stimulation of the inflammatory system.

Adult↗