Rob Pastoor

Simple, rapid, and affordable point-of-care test for the serodiagnosis of typhoid fever

We developed a point-of-care test for the serodiagnosis of typhoid fever in the format of an immunochromatographic lateral flow assay. The flow assay for typhoid fever is based on the detection of Salmonella enterica serotype Typhi lipopolysaccharide-specific immunoglobulin M (IgM) antibodies. The assay was evaluated on serum samples collected in a hospital in South Sulawesi, Indonesia, where typhoid fever is endemic, and the results were compared with culture and Widal test. The sensitivity of this typhoid fever IgM flow assay for samples collected at 1st diagnosis from patients with culture-confirmed typhoid fever was determined to be 59.3%. The sensitivity ranged from 41.2% to 89.5%, depending on the duration of illness. A specificity of 97.8% was calculated based on results obtained for patients with clinical suspicion of typhoid fever that was later excluded. The assay is ideal for use as a point-of-care test in health care centers that lack the expertise and facilities to perform culture or the less specific Widal test. Because of its simplicity, the assay may also be used as a field test in remote areas.

Infection of cattle in Kenya with Brucella abortus biovar 3 and Brucella melitensis biovar 1 genotypes

Brucella melitensis biovar 1 was isolated from bovine milk samples from a herd in central Kenya, and Brucella abortus biovar 3 was isolated from aborted fetus materials and vaginal discharge fluids from cattle in central and eastern provinces of Kenya. All infections including those with B. melitensis were in cattle with reproductive problems kept in mixed herds indicating that cross infection occurs from small ruminants. Multiple-locus variable-number tandem repeat analysis genotyping revealed a close molecular homology of the B. melitensis isolates with an isolate from Israel and a close homology of the B. abortus isolates with an isolate from Uganda indicating that these genotypes have a wide geographic distribution. Infection of cattle with B. melitensis may complicate the control of brucellosis in this country.

Typhoid Fever among Hospitalized Febrile Children in Siem Reap, Cambodia

Typhoid fever was confirmed by positive blood culture in 5 (3.7%) of 134 febrile children hospitalized in Cambodia. Typhoid was suspected in an additional 25 (18.7 %) blood culture-negative children based on: a positive immunoglobulin M lateral flow assay (IgMFA) (16); a positive polymerase chain reaction (PCR) for Salmonella typhi (2); or clinical assessment (7). The specificity of the IgMFA and PCR assays requires further study.

Validation of the Dri-Dot Latex agglutination and IgM lateral flow assays for the diagnosis of typhoid fever in an Egyptian population

Laboratory confirmation of typhoid fever is essential for appropriate medical treatment. Blood culture is a standard test for diagnosis of typhoid fever, but well-equipped diagnostic facilities to perform culture are seldom available in endemic areas. We retrospectively compared 2 diagnostic field tests, a latex agglutination Dri-Dot assay and an IgM Lateral Flow assay, to blood culture, in patients with clinically diagnosed typhoid fever. Sensitivity of the Dri-Dot was 71.4%, and specificity was 86.3% for samples collected at time of first diagnosis. Sensitivity and specificity of IgM Lateral Flow were 80% and 71.4%, respectively. A major limitation of these serologic tests is the limited sensitivity at the early stage of the disease. Performing both tests in parallel increased sensitivity to 84.3%, but decreased specificity to 70.5%. There was a trend towards improved diagnostic performance using either assay over a longer duration of illness. These rapid, point-of-care assays for typhoid fever provide easy-to-interpret results in typhoid-endemic countries and may be most useful in patients presenting 1 week after symptom onset.

Multi-Locus Variable-Number Tandem Repeat Profiling of Salmonella enterica Serovar Typhi Isolates from Blood Cultures and Gallbladder Specimens from Makassar, South-Sulawesi, Indonesia

Multi-locus variable-number tandem repeat analysis differentiated 297 Salmonella enterica serovar Typhi blood culture isolates from Makassar in 76 genotypes and a single unique S. Typhi genotype was isolated from the cholecystectomy specimens of four patients with cholelithiasis. The high diversity in S. Typhi genotypes circulating in Makassar indicates that the number of carriers could be very large, which may complicate disease prevention and control.

Risk Factors of Typhoid Infection in the Indonesian Archipelago

Background Knowledge of risk factors and their relative importance in different settings is essential to develop effective health education material for the prevention of typhoid. In this study, we examine the effect of household level and individual behavioural risk factors on the risk of typhoid in three Indonesian islands (Sulawesi, Kalimantan and Papua) in the Eastern Indonesian archipelago encompassing rural, peri-urban and urban areas. Methods We enrolled 933 patients above 10 years of age in a health facility-based case-control study between June 2010 and June 2011. Individuals suspected of typhoid were tested using the typhoid IgM lateral flow assay for the serodiagnosis of typhoid fever followed by blood culture testing. Cases and controls were defined post-recruitment: cases were individuals with a culture or serology positive result (n = 449); controls were individuals negative to both serology and culture, with or without a diagnosis other than typhoid (n = 484). Logistic regression was used to examine the effect of household level and individual level behavioural risk factors and we calculated the population attributable fraction (PAF) of removing each risk significant independent behavioural risk factor. Results Washing hands at critical moments of the day and washing hands with soap were strong independent protective factors for typhoid (OR = 0.38 95% CI 0.25 to 0.58 for each unit increase in hand washing frequency score with values between 0 = Never and 3 = Always; OR = 3.16 95% CI = 2.09 to 4.79 comparing washing hands with soap sometimes/never vs. often). These effects were independent of levels of access to water and sanitation. Up to two thirds of cases could be prevented by compliance to these practices (hand washing PAF = 66.8 95% CI 61.4 to 71.5; use of soap PAF = 61.9 95%CI 56.7 to 66.5). Eating food out in food stalls or restaurant was an important risk factor (OR = 6.9 95%CI 4.41 to 10.8 for every unit increase in frequency score). Conclusions Major gains could potentially be achieved in reducing the incidence of typhoid by ensuring adherence to adequate hand-washing practices alone. This confirms that there is a pivotal role for ‘software’ related interventions to encourage behavior change and create demand for goods and services, alongside development of water and sanitation infrastructure.