Prevalence and clinical relevance of helminth co-infections among TB patients in urban Tanzania
Abstract
Background
Helminth infections can
negatively affect the immunologic host control, which may
increase the risk of progression from latent
Mycobacterium tuberculosis infection to tuberculosis
(TB) disease and alter the clinical presentation of TB. We
assessed the prevalence and determined the clinical relevance of
helminth co-infection among TB patients and household contact
controls in urban Tanzania.
Methodology
Between November 2013
and October 2015, we enrolled adult (≥18 years) sputum
smear-positive TB patients and household contact controls
without TB during an ongoing TB cohort study in Dar es Salaam,
Tanzania. We used Baermann, FLOTAC, Kato-Katz, point-of-care
circulating cathodic antigen, and urine filtration to diagnose
helminth infections. Multivariable logistic regression models
with and without random effects for households were used to
assess for associations between helminth infection and TB.
Principal findings
A total of 597 TB
patients and 375 household contact controls were included. The
median age was 33 years and 60.2% (585/972) were men. The
prevalence of any helminth infection among TB patients was 31.8%
(190/597) and 25.9% (97/375) among controls.
Strongyloides stercoralis was the predominant helminth
species (16.6%, 161), followed by hookworm (9.0%, 87) and
Schistosoma mansoni (5.7%, 55). An infection with any
helminth was not associated with TB (adjusted odds ratio (aOR)
1.26, 95% confidence interval (CI): 0.88–1.80, p = 0.22),
but S. mansoni infection was (aOR 2.15, 95%
CI: 1.03–4.45, p = 0.040). Moreover, S.
mansoni infection was associated with lower sputum
bacterial load (aOR 2.63, 95% CI: 1.38–5.26, p = 0.004)
and tended to have fewer lung cavitations (aOR 0.41, 95% CI:
0.12–1.16, p = 0.088).
Conclusions/Significance
S. mansoni infection was an independent risk factor for active TB and altered the clinical presentation in TB patients. These findings suggest a role for schistosomiasis in modulating the pathogenesis of human TB. Treatment of helminths should be considered in clinical management of TB and TB control programs.
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Source:
PLOS Neglected Tropical Diseases
