Decline of FoxP3+ Regulatory CD4 T Cells in Peripheral Blood of Children Heavily Exposed to Malaria

FoxP3+ regulatory CD4 T cells (T_regs) help to maintain the delicate balance between pathogen-specific immunity and immune-mediated pathology. Prior studies suggest that T_regs are induced by P. falciparum both in vivo and in vitro; however, the factors influencing T_reg homeostasis during acute and chronic infections, and their role in malaria immunopathogenesis, remain unclear. We assessed the frequency and phenotype of T_regs in well-characterized cohorts of children residing in a region of high malaria endemicity in Uganda. We found that both the frequency and absolute numbers of FoxP3+ T_regs in peripheral blood declined markedly with increasing prior malaria incidence. Longitudinal measurements confirmed that this decline occurred only among highly malaria-exposed children. The decline of T_regs from peripheral blood was accompanied by reduced in vitro induction of T_regs by parasite antigen and decreased expression of TNFR2 on T_regs among children who had intense prior exposure to malaria. While T_reg frequencies were not associated with protection from malaria, there was a trend toward reduced risk of symptomatic malaria once infected with P. falciparum among children with lower T_reg frequencies. These data demonstrate that chronic malaria exposure results in altered T_reg homeostasis, which may impact the development of antimalarial immunity in naturally exposed populations.     

Ethnopharmacological practices by livestock farmers in Uganda: Survey experiences from Mpigi and Gulu districts

Background

There is continued reliance on conventional veterinary drugs including anthelmintics, to some of which resistance has developed. Loss of indigenous technical knowledge (ITK) from societies affects the opportunities for utilization of ethnopharmacological practices unless properly documented. This study was conducted to identify common traditional practices using medicinal plants against helminthosis and other livestock diseases in Mpigi and Gulu districts of Uganda.

Methods

Seven focus group discussions with ten farmers per group plus 18 key informant interviews were held in each district from August to November 2011. Ranking was used to quantify disease burdens and to identify priority livestock and breeds. Samples of each plant were submitted to Makerere University herbarium for identification and documentation. The local name, relative availability and International Union for Conservation of Nature (IUCN) status were recorded.

Results

Seventy six farmers in Mpigi and 74 in Gulu were interviewed. Theileriosis and helminthosis were the most common disease conditions in cattle and goats, respectively. Forty plant species within 34 genera from 22 botanical families were identified, with 20 of these used against helminthosis. Other plants treated wounds and ecto-parasites, theileriosis, retained placenta and bovine ephemeral fever. Non-plant practices (7) and plants cited were used in combination depending on availability. Males older than 40 years had most ethnopharmacological knowledge. Most plants (75%, n?=?40) were common, but 10 were rare. IUCN status was not evaluated for 95% of these plants. Conventional and traditional drug use in Gulu and Mpigi districts was different (χ²?=?24; p?<?0.001). The scientific, English, Luganda and Acholi names of all plants and their availability within the communities are documented herein.

Conclusion

This is the first detailed livestock-related ethnopharmacological study in Gulu district. Farmers in Uganda are still using a variety of practices to treat livestock ailments. Scientific validation and evaluation of conservation status are urgently needed to ensure future availability and knowledge about these plant resources.     

Contrasting long‐term records of biomass burning in wet and dry savannas of equatorial East Africa

Rainfall controls fire in tropical savanna ecosystems through impacting both the amount and flammability of plant biomass, and consequently, predicted changes in tropical precipitation over the next century are likely to have contrasting effects on the fire regimes of wet and dry savannas. We reconstructed the long‐term dynamics of biomass burning in equatorial East Africa, using fossil charcoal particles from two well‐dated lake‐sediment records in western Uganda and central Kenya. We compared these high‐resolution (5 years/sample) time series of biomass burning, spanning the last 3800 and 1200 years, with independent data on past hydroclimatic variability and vegetation dynamics. In western Uganda, a rapid (<100 years) and permanent increase in burning occurred around 2170 years ago, when climatic drying replaced semideciduous forest by wooded grassland. At the century time scale, biomass burning was inversely related to moisture balance for much of the next two millennia until ca. 1750 ad , when burning increased strongly despite regional climate becoming wetter. A sustained decrease in burning since the mid20th century reflects the intensified modern‐day landscape conversion into cropland and plantations. In contrast, in semiarid central Kenya, biomass burning peaked at intermediate moisture‐balance levels, whereas it was lower both during the wettest and driest multidecadal periods of the last 1200 years. Here, burning steadily increased since the mid20th century, presumably due to more frequent deliberate ignitions for bush clearing and cattle ranching. Both the observed historical trends and regional contrasts in biomass burning are consistent with spatial variability in fire regimes across the African savanna biome today. They demonstrate the strong dependence of East African fire regimes on both climatic moisture balance and vegetation, and the extent to which this dependence is now being overridden by anthropogenic activity.     

Biome reconstruction from pollen and plant macrofossil data for Africa and the Arabian peninsula at 0 and 6000 years

Biome reconstruction from pollen and plant macrofossil data provides an objective method to reconstruct past vegetation. Biomes for Africa and the Arabian peninsula have been mapped for 6000 years bp and provide a new standard for the evaluation of simulated palaeovegetation distributions. A test using modern pollen data shows the robustness of the biomization method, which is able to predict the major vegetation types with a high confidence level. The application of the procedure to the 6000 years data set (pollen and plant macrofossil analyses) shows systematic differences from the present that are consistent with the numerous previous regional and continental interpretations, while providing a more extensive and more objective basis for such interpretations. Madagascar, eastern, southern and central Africa show only minor changes in terms of biomes, compared to present. Major changes in biome distributions occur north of 15°N, with steppe in many low-elevation sites that are now desert, and temperate xerophytic woods/scrub and warm mixed forest in the Saharan mountains. These shifts in biome distributions imply significant changes in climate, especially precipitation, between 6000 years and present, reflecting a change in monsoon extent combined with a southward expansion of Mediterranean influence.     

Alcohol Consumption among HIV-Infected Persons in a Large Urban HIV Clinic in Kampala Uganda: A Constellation of Harmful Behaviors

IntroductionAlcohol use by persons living with HIV/AIDS (PLWHA) negatively impacts the public health benefits of antiretroviral therapy (ART). Using a standardized alcohol assessment tool, we estimate the prevalence of alcohol use, identify associated factors, and test the association of alcohol misuse with sexual risk behaviors among PLWHA in Uganda.MethodsA cross-section of PLWHA in Kampala were interviewed regarding their sexual behavior and self-reported alcohol consumption in the previous 6 months. Alcohol use was assessed using the alcohol use disorders identification test (AUDIT). Gender-stratified log binomial regression analyses were used to identify independent factors associated with alcohol misuse and to test whether alcohol misuse was associated with risky sexual behaviors.ResultsOf the 725 subjects enrolled, 235 (33%) reported any alcohol use and 135 (18.6%) reported alcohol misuse, while 38 (5.2%) drank hazardous levels of alcohol. Alcohol misuse was more likely among subjects not yet on ART (adjusted prevalence ratio [aPR] was 1.65 p=0.043 for males and 1.79, p=0.019 for females) and those with self-reported poor adherence (aPR for males=1.56, p=0.052, and for females=1.93, p=0.0189). Belonging to Pentecostal or Muslim religious denominations was protective against alcohol misuse compared to belonging to Anglican and Catholic denominations in both sexes (aPR=0.11 for men, p<0.001, and aPR=0.32 for women, p=0.003). Alcohol misuse was independently associated with reporting risky sexual behaviors (aPR=1.67; 95% CI: 1.07–2.60, p=0.023) among males, but not significant among females (aPR=1.29; 95% CI: 0.95–1.74, p=0.098). Non-disclosure of HIV positive status to sexual partner was significantly associated with risky sex in both males (aPR=1.69; p=0.014) and females (aPR 2.45; p<0.001).ConclusionAlcohol use among PLWHA was high, and was associated with self-reported medication non-adherence, non-disclosure of HIV positive status to sexual partner(s), and risky sexual behaviors among male subjects. Interventions targeting alcohol use and the associated negative behaviors should be tested in this setting.