Zoonotic tuberculosis in a high bovine tuberculosis burden area of Ethiopia.

Background: Tuberculosis (TB) is a major cause of ill health and one of the leading causes of death worldwide, caused by species of the Mycobacterium tuberculosis complex (MTBC), with Mycobacterium tuberculosis being the dominant pathogen in humans and Mycobacterium bovis in cattle. Zoonotic transmission of TB (zTB) to humans is frequent particularly where TB prevalence is high in cattle. In this study, we explored the prevalence of zTB in central Ethiopia, an area highly affected by bovine TB (bTB) in cattle. Method: A convenient sample of 385 patients with pulmonary tuberculosis (PTB, N = 287) and tuberculous lymphadenitis (TBLN, N = 98) were included in this cross-sectional study in central Ethiopia. Sputum and fine needle aspirate (FNA) samples were obtained from patients with PTB and TBLN, respectively, and cultures were performed using BACTEC™ MGIT™ 960. All culture positive samples were subjected to quantitative PCR (qPCR) assays, targeting IS1081, RD9 and RD4 genomic regions for detection of MTBC, M. tuberculosis and M. bovis, respectively. Results: Two hundred and fifty-five out of 385 sampled patients were culture positive and all were isolates identified as MTBC by being positive for the IS1081 assay. Among them, 249 (97.6%) samples had also a positive RD9 result (intact RD9 locus) and were consequently classified as M. tuberculosis. The remaining six (2.4%) isolates were RD4 deficient and thereby classified as M. bovis. Five out of these six M. bovis strains originated from PTB patients whereas one was isolated from a TBLN patient. Occupational risk and the widespread consumption of raw animal products were identified as potential sources of M. bovis infection in humans, and the isolation of M. bovis from PTB patients suggests the possibility of human-to-human transmission, particularly in patients with no known contact history with animals. Conclusion: The detected proportion of culture positive cases of 2.4% being M. bovis from this region was higher zTB rate than previously reported for the general population of Ethiopia. Patients with M. bovis infection are more likely to get less efficient TB treatment because M. bovis is inherently resistant to pyrazinamide. MTBC species identification should be performed where M. bovis is common in cattle, especially in patients who have a history of recurrence or treatment failure.

Spoligotype analysis of Mycobacterium bovis isolates from cattle and assessment of zoonotic TB transmission among individuals working in bovine TB-infected dairy farms in Ethiopia.

Bovine tuberculosis (bTB) is a disease with impact on dairy productivity, as well as having the potential for zoonotic transmission. Understanding the genetic diversity of the disease agent Mycobacterium bovis is important for identifying its routes of transmission. Here we investigated the level of genetic diversity of M. bovis isolates and assessed the zoonotic potential in risk groups of people working in bTB-infected dairy farms in central Ethiopia. M. bovis was isolated and spoligotyped from tissue lesions collected from slaughtered cattle as well as from raw milk collected from bTB positive cows in dairy farms from six urban areas of central Ethiopia. From consented dairy farm workers, knowledge and practices related to zoonotic TB transmission, together with demographic and clinical information, was collected through interviews. Sputum or Fine Needle Aspirate (FNA) samples were collected from suspected TB cases. Spoligotyping of 55 M. bovis isolates that originated either from cattle tissues with tuberculous lesion or from raw milk revealed seven spoligotype patterns where SB1176 was the most prevalent type (47.3%). Most isolates (89.1%) were of the M. bovis African 2 clonal complex. All sputum and FNA samples from 41 dairy farm workers with symptoms of TB were culture negative for any mycobacteria. Among the 41 TB suspected farm workers, 61% did not know about bTB in cattle and its zoonotic potential, and over two-third of these workers practiced raw milk consumption. Our spoligotype analysis suggests a wider transmission of a single spoligotype in the study area. The results reported here may be useful in guiding future work to identify the source and direction of bTB transmission and hence design of a control strategy. Isolation of M. bovis from milk, knowledge gap on zoonotic TB and practice of consumption of raw milk in the study population showed potential risk for zoonotic transmission.

Vitamin D Deficiency is Associated with Increased Use of Antimicrobials among Preschool Girls in Ethiopia.

Preschool children in Addis Ababa, Ethiopia, are highly exposed to influenza viruses. Factors related to infections, nutrition, and environmental conditions that might explain the burden of influenza among these children were investigated. Ninety-five preschool children, 48 girls and 47 boys, were followed clinically for 12 months. Illness and immune responses to influenza; three other respiratory viruses; five airway pathogenic bacteria; and levels of vitamins D, A, and B12 were assessed. Most of the children had antibodies to numerous respiratory viral and bacterial agents at study start, and many were infected during follow-up. Twenty-five girls and 25 boys fell ill during the study, and were treated with one or more courses of systemic antimicrobials. Ninety percent of both girls and boys had 25-hydroxyvitamin D [25(OH)D] levels below the recommended levels. While there was no overall difference in the levels of vitamins D, A, and B12 between girls and boys, treated girls had significantly lower 25(OH)D levels than non-treated girls and treated boys. There was a considerable number of short for age children, but only the short treated girls had significantly lower 25(OH)D levels than the non-treated children. Preschool girls with low 25(OH)D levels were more vulnerable to pathogenic microbes than boys.

High Prevalence of Humoral and Cellular Immunity to Influenza Viruses in Preschool Children Living in Addis Ababa, Ethiopia.

BACKGROUND: Influenza in children who reside in tropical and subtropical regions has until recently been regarded as insignificant. However, new evidence suggests that it significantly impacts hospitalization and promotes secondary bacterial coinfections. Ethiopia is situated in a subtropical area where influenza viruses are likely to circulate year round. METHODS: Clinical data were recorded in a cohort of 103 healthy preschool children recruited in Addis Ababa, Ethiopia. Humoral and cellular immune responses to influenza virus were determined by hemagglutination inhibition (HI) and interferon-γ enzyme-linked immunospot assays. RESULTS: Ninety-six percent of the children (2-5 years old) had pre-existing HI antibody responses to 1 or more of the circulating influenza A subtypes, H1N1 (51%), H3N2 (86%), or influenza B (51%) strains. At the age of 4, all children had been infected with at least 1 strain, and 75% had been infected with 2-4 different viral strains. CD4+ and CD8+ T-cell responses against conserved viral antigens increased with repeated exposures, indicating boosting of cross-reactive cellular immunity. Malnutrition did not seem to affect these immune responses to influenza. CONCLUSIONS: Influenza is highly prevalent among children in this area of Ethiopia. Due to the risk of secondary bacterial pneumonia, increased influenza awareness might benefit child health.

Ex-vivo characterization of regulatory T cells in pulmonary tuberculosis patients, latently infected persons, and healthy endemic controls.

BACKGROUND: Regulatory T cells (Treg) are an essential arm of adaptive immunity not only in tolerance and autoimmunity but also in infectious diseases. In Tuberculosis (TB), it has been suggested that the frequency of Tregs is higher in the blood of TB patients when compared to healthy controls with subsequent decline after treatment. However, with the discovery that FOXP3, the hallmark marker of Tregs, is not exclusive to Tregs and the lack of specific markers for Tregs, it has been a challenge to fully understand the role of Tregs in TB. METHOD: We isolated PBMC from smear positive TB patients (TB, N = 13) before and after treatment, latent TB infected participants (LTBI, N = 8), and healthy endemic controls (EC, N = 9) and evaluated the frequency of different populations of Tregs and expression of FOXP3 by flowcytometry using six markers. RESULTS: The findings in this study showed that the association of Treg frequency with TB disease depends on the phenotypic markers used. While the frequency of CD4(+)CD25(+/hi) T cells was higher in TB patients compared to LTBI individuals, there was no difference in the frequency of CD4(+)CD25(+)FOXP3(+)CD127(lo) Treg among TB, LTBI, or EC. However, delineation of Tregs into active and naïve subsets revealed a significant increase in FOXP3 expression in active primed Tregs (CD4(+)CD25(+)FOXP3(+)CD127(lo)CD45RO(+)Ki-67(+)) of TB patients compared to LTBI and EC; and a significantly higher frequency of resting primed (CD45RO(+)Ki-67(-)) Treg in QuantiFERON negative EC compared to TB patients. After treatment completion, there was a significant decline in the frequency of active primed Treg, median (IQR) from 12.4% (9.5-21.9) of Tregs to 9.3% (7.0-12.2); P = 0.003 Wilcoxon signed rank test. We conclude that Treg subsets may be differentially regulated and expressed in TB disease, cure, and infection.