Maternal Latent Mycobacterium tuberculosis Does Not Affect the Infant Immune Response Following BCG at Birth: An Observational Longitudinal Study in Uganda

Background: BCG has low efficacy in tropical countries. We hypothesized that maternal latent Mycobacterium tuberculosis (M.tb) infection (LTBI) results in fetal tolerance to mycobacterial antigens and impaired responses to BCG immunization. Methods: We enrolled 132 LTBI-positive and 150 LTBI-negative mothers and their babies in Entebbe, Uganda. Infants were BCG-immunized at birth. Cord blood and samples at weeks 1, 4, 6, 10, 14, 24, and 52 were analyzed for cytokine/chemokine responses to M.tb antigens by Luminex 17-plex assay in 6-day whole blood cultures and antibody responses by ELISA. Of the 17 Luminex analytes, seven (IL-2, IL-5, IL-10, IL-13, IL-17A, TNF, and IFN-γ) were included in the main analysis as they were considered most likely to represent T cell responses. Immune sensitization was defined as a detectable cord blood cytokine response to PPD for any of the seven cytokines. Patterns of cytokine and antibody responses were compared between infants of mothers with and without LTBI using linear mixed models adjusting for confounders. Results: Most infants (73%) were sensitized in utero to M.tb antigens, with no overall difference seen between infants born to mothers with or without LTBI. Patterns of post-BCG cytokine and antibody responses to mycobacterial antigens were similar between the two infant groups. Conclusions: Our data do not support the hypothesis that maternal LTBI results in an impaired response to BCG immunization, in Ugandan infants. BCG vaccination at or shortly after birth is likely to be beneficial to all infants, irrespective of maternal LTBI status.UK Medical Research Council; DELTAS Africa Initiative SSACAB; DELTAS Initiative MUIIplus; Commonwealth Scholarships Commission; MRC/UVRI and LSHTM Uganda Research Unit; EU Horizon 2020 programme; MRC London Intercollegiate Doctoral Training Partnership; MRC; UK Medical Research Council (MRC); UK Department for International Development (DFID)

Characterising the Coffee-Banana Agroforestry Systems: an Entry Point for Promoting Coffee and Banana Growing in mid-Northern Uganda

This study was conducted in the mid-Northern Ugandan districts of Nwoya, Gulu, Lira, Apach and Oyam to characterise the coffee-banana agroforestry systems. Thirty fields with coffee-banana agroforestry systems were selected and the level of field and crop management determined. Additionally, five coffee and banana plants were randomly selected and assessed for pests and diseases. All fields had Robusta coffee type whereas cooking bananas were the dominant clone (45%). Field management was limited. More than 80% of the fields had no bands, trenches or cover-crops. Most of the fields were lowly weeded (46.7%) and mulched (60%). Intercropping was low with 20% having maize or cassava. Similarly, most fields were lowly inter-planted with trees (40%) with only 28 tree/shrub species and dominated by fruit trees; namely oranges (70%), mangoes (63.3%) and pawpaw (56.7%) of the total number of tree species observed in the systems. Generally, 40% of coffee fields had not been de-suckered, pruned or changed cycle. However, at least 35% of the coffee fields were highly pruned and their cycle changed. For bananas, more than 70% of the fields were not de-suckered, propped or their corms removed, but 63% of them had been de-leafed and de-budded at a low to moderate level. Leaf skeletonisers and coffee leaf rust were the most observed pest (77.3%) and disease (15.3%) respectively. Pest damage was limited in bananas, though black Sigatoka was the commonest disease observed (56%). It is concluded that the region has embraced the systems but there is need for farmers to be provided with the right species of coffee, banana and trees.Keywords: Agroforestry-systems, cooking-bananas, Robusta-coffee

Prevalence and incidence of four common bean root rots in Uganda

Root rots are one of the main biotic constraints to common bean (Phaseolus vulgaris L.) production, causing losses estimated at 221 000 metric tons a year in sub-Saharan Africa. Until recently, root rots in Ugandan common bean agroecologies were mostly caused by Pythium and Fusarium spp., especially in high altitude areas. But now, severe root rots are observed in low and medium altitude agroecologies characterized by dry and warm conditions. The objective of our study was therefore to ascertain the current prevalence and incidence of common bean root rot diseases in Ugandan common bean agroecologies. Our results show that root rots were present in all seven agroecologies surveyed. Overall, the most rampant root rot was southern blight caused by Sclerotium rolfsii Sacc., followed by root rots caused by Fusarium spp., Pythium spp. and Rhizoctonia solani, respectively. Our study clearly showed the influence of environmental conditions on the prevalence and incidence of common bean root rots. While Fusarium and Pythium root rots are favoured under low air temperature and high air humidity in highland areas, high incidence of southern blight is favoured by warm and moist conditions of lowland areas. The prevalence and incidence of common bean root rots was mapped, providing a reliable baseline for future studies. Similarly, hotspots identified for common bean root rots will be a very useful resource for evaluation of germplasm and breeding lines for resistance to root rots