Evaluation of the T-SPOT(RTM).TB test in the diagnosis of latent tuberculosis infection in HIV-infected children in Uganda

Background. About a third of the world’s population is infected with tuberculosis (TB) with sub-Saharan Africa being the worst hit. Uganda is ranked 16th among the countries with the biggest TB burden. The burden in children however has not been determined. The burden of TB has been worsened by the advent of HIV and TB is the leading cause of mortality in HIV infected individuals. Development of TB disease can be prevented if TB is diagnosed during its latent stage and treated with isoniazid. For over a century, latent TB infection (LTBI) was diagnosed using the Tuberculin Skin Test (TST). New interferon gamma release assays (IGRA) have been approved by FDA for the diagnosis of LTBI and adult studies have shown that IGRAs are superior to the TST but there have been few studies in children especially in areas of high TB and HIV endemicity. ^ Objective. The objective of this study was to examine whether the IGRAs had a role in LTBI diagnosis in HIV infected children in Uganda. ^ Methods. Three hundred and eighty one (381) children were recruited at the Baylor College of Medicine-Bristol Meyers Squibb Children’s Clinical Center of Excellence at Mulago Hospital, Kampala, Uganda between March and August 2010. All the children were subjected to a TST and T-SPOT ®.TB test which was the IGRA chosen for this study. Sputum examination and chest x-rays were also done to rule out active TB. ^ Results. There was no statistically significant difference between the tests. The agreement between the two assays was 95.9% and the kappa statistic was 0.7 (95% CI: 0.55–0.85, p-value<0.05) indicating a substantial or good agreement. The TST was associated with older age and higher weight for age z-scores but the T-SPOT®. TB was not. Both tests were associated with history of taking anti-retroviral therapy (ART). ^ Conclusion. Before promoting use of IGRAs in children living in HIV/TB endemic countries, more research needs to be done. ^

Seroprevalence of Chagas' disease in Texas among shelter dogs in Houston and the Rio Grande Valley region and its implication for human infection

Chagas’ disease, also called American Trypanosomiasis, is a vector-borne disease caused by the protozoan parasite Trypanosoma cruzi. T. cruzi is spread by triatomine insects, commonly referred to as ‘kissing bugs.’ After the insect takes a blood meal from its animal or human host, it usually defecates near the bite wound. The parasite is present in the feces, and when rubbed into the bite wound or mucous membranes by the host, infection ensues. Chagas’ disease is highly endemic in Central and South America where it originated. Many people in these endemic areas live in poor conditions surrounded by animals, mainly dogs, that can serve as a possible link to human infection. In Chagas’ endemic countries, dogs can be used as a sentinel to infer risk for human infection. In Texas, the prevalence of Chagas’ and risk for human infection is largely unknown. This study aimed to determine the prevalence of Chagas’ disease in shelter dogs in Houston, Texas and the Rio Grande Valley region by using an immunochromatographic assay (Chagas’ Stat-Pak) to test for the presence of T. cruzi antibodies. Of the 822 samples tested, 26 were found to be positive (3.2%). In both locations, Chagas’ prevalence increased over time. This study found that dogs, especially strays, can serve as sentinels for disease activity. Public health authorities can implement this strategy to understand the level of Chagas’ activity in a defined geographic area and prevent human infection.^

The evidence for groundwater as a source of enteric illness in developing countries: A systematic review of the literature

Groundwater constitutes approximately 30% of freshwater globally and serves as a source of drinking water in many regions. Groundwater sources are subject to contamination with human pathogens (viruses, bacteria and protozoa) from a variety of sources that can cause diarrhea and contribute to the devastating global burden of this disease. To attempt to describe the extent of this public health concern in developing countries, a systematic review of the evidence for groundwater microbially-contaminated at its source as risk factor for enteric illness under endemic (non-outbreak) conditions in these countries was conducted. Epidemiologic studies published in English language journals between January 2000 and January 2011, and meeting certain other criteria, were selected, resulting in eleven studies reviewed. Data were extracted on microbes detected (and their concentrations if reported) and on associations measured between microbial quality of, or consumption of, groundwater and enteric illness; other relevant findings are also reported. In groundwater samples, several studies found bacterial indicators of fecal contamination (total coliforms, fecal coliforms, fecal streptococci, enterococci and E. coli), all in a wide range of concentrations. Rotavirus and a number of enteropathogenic bacteria and parasites were found in stool samples from study subjects who had consumed groundwater, but no concentrations were reported. Consumption of groundwater was associated with increased risk of diarrhea, with odds ratios ranging from 1.9 to 6.1. However, limitations of the selected studies, especially potential confounding factors, limited the conclusions that could be drawn from them. These results support the contention that microbial contamination of groundwater reservoirs—including with human enteropathogens and from a variety of sources—is a reality in developing countries. While microbially-contaminated groundwaters pose risk for diarrhea, other factors are also important, including water treatment, water storage practices, consumption of other water sources, water quantity and access to it, sanitation and hygiene, housing conditions, and socio-economic status. Further understanding of the interrelationships between, and the relative contributions to disease risk of, the various sources of microbial contamination of groundwater can guide the allocation of resources to interventions with the greatest public health benefit. Several recommendations for future research, and for practitioners and policymakers, are presented.^