Background

M.tuberculosis (M.tb) is associated with enhanced T helper cell type 1 (Th1) immune responses while helminth infection is associated with T helper cell type 2 (Th2) immune responses. Our aim was to investigate whether helminth infection could influence the ability to generate an appropriate Th1 immune response that is characterized by a positive tuberculin skin test (TST), in M.tb exposed children.

Methods

We completed a community-based, cross sectional household contact tracing study, using matched enrolment of HIV negative children with and without documented household M.tb exposure. We documented demographics, clinical characteristics, HIV status, M.tb exposure (using a standard contact score) and M.tb infection status (TST > = 10 mm). Ascaris lumbricoides-specific IgE was used as proxy for Ascaris infection/exposure.

Results

Of 271 children (median age 4 years (range: 4 months to 15 years)) enrolled, 65 participants (24%) were serum positive for Ascaris IgE. There were 168 (62%) children with a documented household tuberculosis contact and 107 (40%) were (TST) positive overall.

A positive TST was associated with increasing age (Odds Ratio (OR) =1.17, p < 0.001), increasing M.tb contact score (OR = 1.17, p < 0.001), previous tuberculosis treatment (OR = 4.8, p = 0.06) and previous isoniazid preventive treatment (OR = 3.16, p = 0.01). A visible bacillus Calmette-Guérin (BCG) scar was associated with reduced odds of being TST positive (OR = 0.42, p = 0.01).

Ascaris IgE was not associated with TST status in univariate analysis (OR = 0.9, p = 0.6), but multivariable logistic regression analysis suggested an inverse association between Ascaris IgE status and a positive TST (OR = 0.6, p = 0.08), when adjusted for age, and M.tb contact score. The addition of an age interaction term to the model suggested that the age effect was stronger among Ascaris IgE positive children; the effect of being Ascaris IgE positive significantly reduced the odds of being TST positive amongst younger children while this effect weakened with increasing age.

Conclusions

Our preliminary findings highlight a high prevalence of both Ascaris exposure/infection and M.tb infection in children in an urban setting. Helminth exposure/infection may reduce the immune response following M.tb exposure when controlling for epidemiological and clinical covariates. These findings might be relevant to the interpretation of immunological tests of M.tb infection in children.

Serum samples and sociodemographic data were obtained from 1,209 Ohio residents. West Nile virus immunoglobulin M (IgM) and IgG antibodies were detected by enzyme-linked immunosorbent assay and confirmed. Children were 4.5 times more likely to become infected yet 110× less likely to have neuroinvasive disease develop.

Human West Nile virus (WNV) infection was first detected in Cuyahoga County, Ohio in 2002. During that year's extensive epidemic/epizootic among non-immune human and bird populations, the county experienced 155 cases of severe human WNV neuro-invasive disease (WNND, incidence: 11.1 cases/100,000), with 11 fatalities. Structured serosurveys indicated that 1.9%, or ~ 26,000 of county residents (pop. = 1,372,303) were infected that year. In early 2003, in order to better focus monitoring and control efforts, we used a Geographic Information System (GIS) approach and spatial statistical analysis to identify the association of environmental factors and human population structure with the observed local risk for WNV transmission. Within the varied range of urban/suburban/rural habitats across the 458 mi2 (1186 km2) county, exploratory analysis indicated significant clustering of WNND risk in inner-ring suburbs. Subsequent discriminant factor analysis based on inputs of census and land-use/ land cover data was found to effectively classify sub-areas of the county having low, medium, and high WNV risk. On a 4 mi2 (1036 ha.) quadrat scale of resolution, higher risk of human infection was significantly associated with higher-income areas, increased fractionation of habitat, and older housing, while it was negatively associated with areas of agricultural land, wetland, or forest. The areal classification of WNV transmission risk has been validated over time through detection of increased local Culex spp. mosquito density (2002–2006), and increased frequency of WNV positive mosquito pools within the medium- and high-risk quadrats. This timely working identification of the transmission scale effectively focused control interventions against newly invasive WNV in a complex North American habitat.

Background

The study was conducted at a high TB-HIV burden primary health community clinic in Cape Town, South Africa. We describe the management of children under five years of age in household contact with a smear and/or culture-positive adult TB case.

Methods

This study was a record review of routinely-collected programme data.

Results

A total of 1094 adult TB case folders were reviewed. From all identified contacts, 149 children should have received IPT based on local guidelines; in only 2/149 IPT was initiated. Management of child contacts of sputum smear and/or culture-positive compared to sputum-negative TB patients were similar.

Conclusions

IPT delivery to children remains an operational challenge, especially in high TB-HIV burden communities. A tool to improve IPT management and targeting sputum smear and/or culture-positive TB child contacts may overcome some of these challenges and should be developed and piloted in such settings.

SYNOPSIS

Objectives.

Emerging evidence suggests that children are at higher risk for West Nile virus (WNV) exposure, but may have a lower risk for infection-related morbidity and mortality. Limited data exist regarding risk determinants of childhood WNV infection. We conducted a survey to analyze the differences between pediatric and adult behavior relevant to WNV exposure.

Methods.

Residents of participating sampled households responded to a questionnaire that measured knowledge, attitudes, personal protective behaviors, and clinical history to evaluate the association between personal behavior and exposure to WNV.

Results.

Children were more likely to have high levels of outdoor exposure compared to adults (83% vs. 70%). Children were less likely to avoid going outdoors (4% vs. 13%) and to wear long sleeves or pants compared to adults (8% vs. 19%). Both groups were highly educated about WNV. Television, not health-care provider education, was the most common source of WNV information. Participants were more concerned about WNV infection than pesticide usage.

Conclusions.

Our study demonstrates that children exhibit behaviors that could put them at greater risk for WNV infection and suggests that children could benefit from greater education about practices that can decrease WNV exposure to limit their risk for infection.