Understanding the Role of Gender in Trichiasis Case Finding in Tanzania.

PURPOSE: Despite the importance of trachomatous trichiasis (TT) case-finding activities in national trachoma elimination campaigns, the scientific literature on the determinants of good outcomes - finding and managing all TT cases - is still sparse. In Tanzania, we studied differences in case finding activities and outcomes between male and female case finders. METHODS: This case study was conducted in two districts in Tanzania in 2021-2022. Quantitative data were extracted from case finder forms and outreach registers, and qualitative data were collected through direct observation, interviews, and focus group discussions. RESULTS: Across both districts, more males were trained as case finders (68%). Productivity differences were minor, not statistically significant, between male and female case finders regarding the number of households visited and the number of adults examined. Whether identified by a male or female case finder, similar proportions of men and women suspected to have TT were subsequently managed. There is evidence that suggests that female case finders were more active in supporting suspected and confirmed TT cases to access follow-up services. CONCLUSION: The findings do not suggest that gender balance in the recruitment of TT case finders would have led to better TT campaign outcomes in the study districts. Programmes may benefit from integrating gender considerations in the design and implementation of case finding activities - e.g. in monitoring gender differences among case finders and the relationship with key outcomes. This study also highlights how women with TT face greater barriers to care.

Comparative phylogeography of Aedes mosquitoes and the role of past climatic change for evolution within Africa.

The study of demographic processes involved in species diversification and evolution ultimately provides explanations for the complex distribution of biodiversity on earth, indicates regions important for the maintenance and generation of biodiversity, and identifies biological units important for conservation or medical consequence. African and forest biota have both received relatively little attention with regard to understanding their diversification, although one possible mechanism is that this has been driven by historical climate change. To investigate this, we implemented a standard population genetics approach along with Approximate Bayesian Computation, using sequence data from two exon-primed intron-crossing (EPIC) nuclear loci and mitochondrial cytochrome oxidase subunit I, to investigate the evolutionary history of five medically important and inherently forest dependent mosquito species of the genus Aedes. By testing different demographic hypotheses, we show that Aedes bromeliae and Aedes lilii fit the same model of lineage diversification, admixture, expansion, and recent population structure previously inferred for Aedes aegypti. In addition, analyses of population structure show that Aedes africanus has undergone lineage diversification and expansion while Aedes hansfordi has been impacted by population expansion within Uganda. This congruence in evolutionary history is likely to relate to historical climate-driven habitat change within Africa during the late Pleistocene and Holocene epoch. We find differences in the population structure of mosquitoes from Tanzania and Uganda compared to Benin and Uganda which could relate to differences in the historical connectivity of forests across the continent. Our findings emphasize the importance of recent climate change in the evolution of African forest biota.

Mosquito-borne viruses circulating in Kinshasa, Democratic Republic of the Congo.

BACKGROUND: Diseases caused by mosquito-borne viruses are among the most important emerging diseases that threaten human and animal health, particularly in Africa. However, little attention has been paid to these diseases in the Democratic Republic of the Congo (DRC). The present cross-sectional study was undertaken between March and May 2014 to investigate the presence of mosquito-borne viruses in mosquitoes collected from five municipalities of Kinshasa, DRC. METHODS: Mosquitoes were collected using BG-Sentinel traps and battery-powered aspirators. Female mosquitoes were pooled according to their genera and sampling locations, preserved in RNAlater, and later screened for viruses using reverse transcription PCR (RT-PCR) assays. RESULTS: A total of 2922 mosquitoes were collected and 29 pools of female mosquitoes, containing approximately 30 mosquitoes each, were tested. Twelve of the 29 (41.4%) mosquito pools were found to be infected with at least one arbovirus, with eight (27.5%) pools positive for Alphavirus, nine (31%) for Flavivirus, and five (17.2%) for Bunyaviridae. Chikungunya, o'nyong'nyong, and Rift valley fever viruses were detected. CONCLUSIONS: The present study shows that mosquitoes in Kinshasa carry mosquito-borne viruses that may have serious public health implications. Further investigations on the presence of mosquito-borne viruses in the human and livestock populations of Kinshasa and DRC are recommended.

Historical environmental change in Africa drives divergence and admixture of Aedes aegypti mosquitoes: a precursor to successful worldwide colonization?

Increasing globalization has promoted the spread of exotic species, including disease vectors. Understanding the evolutionary processes involved in such colonizations is both of intrinsic biological interest and important to predict and mitigate future disease risks. The Aedes aegypti mosquito is a major vector of dengue, chikungunya and Zika, the worldwide spread of which has been facilitated by Ae. aegypti's adaption to human-modified environments. Understanding the evolutionary processes involved in this invasion requires characterization of the genetic make-up of the source population(s). The application of approximate Bayesian computation (ABC) to sequence data from four nuclear and one mitochondrial marker revealed that African populations of Ae. aegypti best fit a demographic model of lineage diversification, historical admixture and recent population structuring. As ancestral Ae. aegypti were dependent on forests, this population history is consistent with the effects of forest fragmentation and expansion driven by Pleistocene climatic change. Alternatively, or additionally, historical human movement across the continent may have facilitated their recent spread and mixing. ABC analysis and haplotype networks support earlier inferences of a single out-of-Africa colonization event, while a cline of decreasing genetic diversity indicates that Ae. aegypti moved first from Africa to the Americas and then to Asia. ABC analysis was unable to verify this colonization route, possibly because the genetic signal of admixture obscures the true colonization pathway. By increasing genetic diversity and forming novel allelic combinations, divergence and historical admixture within Africa could have provided the adaptive potential needed for the successful worldwide spread of Ae. aegypti.

Molecular Differentiation of the African Yellow Fever Vector Aedes bromeliae (Diptera: Culicidae) from Its Sympatric Non-vector Sister Species, Aedes lilii.

INTRODUCTION: Yellow fever continues to be a problem in sub-Saharan Africa with repeated epidemics occurring. The mosquito Aedes bromeliae is a major vector of yellow fever, but it cannot be readily differentiated from its non-vector zoophilic sister species Ae. lilii using morphological characters. Genetic differences have been reported between anthropophilic Ae. bromeliae and zoophilic Ae. lilii and between forest and domestic populations. However, due to the application of different molecular markers and non-overlapping populations employed in previous studies, interpretation of species delimitation is unclear. METHODOLOGY/PRINCIPLE FINDINGS: DNA sequences were generated from specimens of Ae. simpsoni s.l. from the Republic of Benin, Tanzania and Uganda for two nuclear genes apolipophorin 2 (apoLp2) and cytochrome p450 (CYPJ92), the ribosomal internal transcribed spacer region (ITS) and the mitochondrial cytochrome c oxidase (COI) barcoding region. Nuclear genes apoLp2 and CYPJ92 were unable to differentiate between species Ae. bromeliae and Ae. lilii due to ancestral lineage sorting, while ITS sequence data provided clear topological separation on a phylogeny. The standard COI barcoding region was shown to be subject to species introgression and unable to clearly distinguish the two taxa. Here we present a reliable direct PCR-based method for differentiation of the vector species Ae. bromeliae from its isomorphic, sympatric and non-biomedically important sister taxon, Ae. lilii, based on the ITS region. Using molecular species verification, we describe novel immature habitats for Ae. lilii and report both sympatric and allopatric populations. Whereas only Ae. lilii is found in the Republic of Benin and only Ae. bromeliae in Tanzania, both species are sympatric in Uganda. CONCLUSIONS/SIGNIFICANCE: Our accurate identification method will allow informed distribution and detailed ecological studies that will facilitate assessment of arboviral disease risk and development of future targeted vector control.

Glaucoma after pediatric cataract surgery in a population with limited access to care.

BACKGROUND: Cataract is a leading cause of childhood blindness in eastern Africa and other resource-constrained regions around the world, and high-quality surgical centers are increasingly responding to this challenge. Despite evidence concerning the ongoing risk of postoperative glaucoma after lensectomy, little is known of the incidence of glaucoma after pediatric cataract surgery in Africa. We sought to evaluate the frequency and predictors of postoperative glaucoma in this setting. METHODS: The medical records of all children who underwent surgery for congenital or developmental cataract between 2003 and 2005 at the Kilimanjaro Christian Medical Centre were retrospectively reviewed to determine the incidence of postoperative glaucoma. Potential risk factors were evaluated by means of logistic regression. RESULTS: Cumulative incidence of glaucoma at 3 years was 6.5% (95% CI, 2.5-16.0), and the annual incidence rate was 2.0 cases per 100 operated eyes (95% confidence interval, 0.74-4.37). Total time of follow-up and absence of primary intraocular lens implantation correlated with risk for postoperative glaucoma, but multivariate analysis could not confirm independent associations. CONCLUSIONS: As cataract surgical rates continue to increase and pediatric ophthalmology centers in Africa progress toward the goals of Vision 2020: The Right to Sight, renewed efforts must be directed toward the long-term postoperative care of all children undergoing operation for pediatric cataract.

Comparing key informants to health workers in identifying children in need of surgical eye care services.

The objective of the study was to compare the productivity of key informants (KIs) and dedicated health workers (HWs) in identifying children with surgical eye care needs. In two regions of Tanzania, KIs and HWs were trained to identify and register children with severe visual impairment or blindness, with the objective of providing them with surgical eye care services. Identified children were examined at predetermined sites. The total numbers of children in need of surgical services identified by KIs and HWs were compared to measure their relative efficacy. A total of 197 KIs and 63 HWs were trained in the two regions. Five hundred and forty-nine children were identified by KIs and 22 children were identified by HWs: KIs were three times more productive than the HWs. Most of the children identified and examined had serious eye pathology and received surgery or low vision services. The cost per child found was significantly less for children found by KI compared to HW. The study indicates that, in rural Africa, finding children in need of surgical and low vision interventions and ensuring that they are properly screened appears to require community-based efforts.