Potential effects of warmer worms and vectors on onchocerciasis transmission in West Africa

Development times of eggs, larvae and pupae of vectors of onchocerciasis (Simulium spp.) and of Onchocerca volvulus larvae within the adult females of the vectors decrease with increasing temperature. At and above 25C,the parasite could reach its infective stage in less than 7 days when vectors could transmit after only two gonotrophic cycles. After incorporating exponential functions for vector development into a novel blackfly population model, it was predicted that fly numbers in Liberia and Ghana would peak at air temperatures of 29C and 34C, about 3C and 7C above current monthly averages, respectively; parous rates of forest flies (Liberia) would peak at 298C and of savannah flies (Ghana) at 308C. Small temperature increases (less than 28C) might lead to changes in geographical distributions of different vector taxa. When the new model was linked to an existing framework for the population dynamics of onchocerciasis in humans and vectors, transmission rates and worm loads were projected to increase with temperature to at least 338C. By contrast, analyses of field data on forest flies in Liberia and savannah flies in Ghana, in relation to regional climate change predictions, suggested, on the basis of simple regressions, that 13–41% decreases in fly numbers would be expected between the present and before 2040. Further research is needed to reconcile these conflicting conclusions

Onchocerciasis transmission in Ghana: biting and parous rates of host-seeking sibling species of the Simulium damnosum complex

Background: Ghana is renowned for its sibling species diversity of the Simulium damnosum complex, vectors of Onchocerca volvulus. Detailed entomological knowledge becomes a priority as onchocerciasis control policy has shifted from morbidity reduction to elimination of infection. To date, understanding of transmission dynamics of O. volvulus has been mainly based on S. damnosum sensu stricto (s.s.) data. We aim to elucidate bionomic features of vector species of importance for onchocerciasis elimination efforts. Methods: We collected S. damnosum sensu lato from seven villages in four Ghanaian regions between 2009 and 2011, using standard vector collection, and human- and cattle-baited tents. Taxa were identified using morphological and molecular techniques. Monthly biting rates (MBR), parous rates and monthly parous biting rates (MPBR) are reported by locality, season, trapping method and hour of collection for each species. Results: S. damnosum s.s./S. sirbanum were collected at Asubende and Agborlekame, both savannah villages. A range of species was caught in the Volta region (forest-savannah mosaic) and Gyankobaa (forest), with S. squamosum or S. sanctipauli being the predominant species, respectively. In Bosomase (southern forest region) only S. sanctipauli was collected in the 2009 wet season, but in the 2010 dry season S. yahense was also caught. MBRs ranged from 714 bites/person/month at Agborlekame (100% S. damnosum s.s./S. sirbanum) to 8,586 bites/person/month at Pillar 83/Djodji (98.5% S. squamosum). MBRs were higher in the wet season. In contrast, parous rates were higher in the dry season (41.8% vs. 18.4%), resulting in higher MPBRs in the dry season. Daily host-seeking activity of S. damnosum s.s./S. sirbanum was bimodal, whilst S. squamosum and S. sanctipauli had unimodal afternoon peaks. Conclusions: The bionomic differences between sibling species of the S. damnosum complex need to be taken into account when designing entomological monitoring protocols for interventions and parameterising mathematical models for onchocerciasis control and elimination

Onchocerciasis transmission in Ghana: Persistence under different control strategies and the role of the simuliid vectors

Background: The World Health Organization (WHO) aims at eliminating onchocerciasis by 2020 in selected African countries. Current control focuses on community-directed treatment with ivermectin (CDTI). In Ghana, persistent transmission has been reported despite long-term control. We present spatial and temporal patterns of onchocerciasis transmission in relation to ivermectin treatment history. Methodology/Principal Findings: Host-seeking and ovipositing blackflies were collected from seven villages in four regions of Ghana with 3–24 years of CDTI at the time of sampling. A total of 16,443 flies was analysed for infection; 5,812 (35.3%) were dissected for parity (26.9% parous). Heads and thoraces of 12,196 flies were dissected for Onchocerca spp. and DNA from 11,122 abdomens was amplified using Onchocerca primers. A total of 463 larvae (0.03 larvae/fly) from 97 (0.6%) infected and 62 (0.4%) infective flies was recorded; 258 abdomens (2.3%) were positive for Onchocerca DNA. Infections (all were O. volvulus) were more likely to be detected in ovipositing flies. Transmission occurred, mostly in the wet season, at Gyankobaa and Bosomase, with transmission potentials of, respectively, 86 and 422 L3/person/month after 3 and 6 years of CDTI. The numbers of L3/1,000 parous flies at these villages were over 100times the WHO threshold of one L3/1,000 for transmission control. Vector species influenced transmission parameters. At Asubende, the number of L3/1,000 ovipositing flies (1.4, 95% CI = 0–4) also just exceeded the threshold despite extensive vector control and 24 years of ivermectin distribution, but there were no infective larvae in host-seeking flies. Conclusions/Significance: Despite repeated ivermectin treatment, evidence of O. volvulus transmission was documented in all seven villages and above the WHO threshold in two. Vector species influences transmission through biting and parous rates and vector competence, and should be included in transmission models. Oviposition traps could augment vector collector methods for monitoring and surveillance

Domesticity, Tourism, and the National Parks in Muir\u27s Late Writings

In this paper, I argue that the development of Muir\u27s conception of what a park should be, and his success at making that idea a reality, rested on the interaction of nineteenth-century notions of domesticity with twentieth-century notions of tourism. Many critics and biographers of Muir have observed a general shift in his priorities over time, away from an emphasis on the experience of the solitary observer in nature and toward a more lenient understanding of the experience of other humans in the world, both as residents of domestic space and tourists in the wilderness. This paper contributes to recent discussions of the domestic in Muir\u27s writing by Michael Smith, Robert Dorman, and Steven Holmes in its argument that Muir\u27s late writings about Yosemite were not an attempt to camouflage his true beliefs but were rather a reflection of the domesticating influence exerted by both his audience and his family. In particular, I argue that, following his marriage to Louie Strenzel in 1880 and during the years he spent with her and their daughters in Martinez, Muir gradually came to value the domestic--and its touristic counterpart--as an essential element in the preservation of nature through the national parks

Domesticity, Tourism, and the National Parks in Muir\u27s Late Writings

In this paper, I argue that the development of Muir\u27s conception of what a park should be, and his success at making that idea a reality, rested on the interaction of nineteenth-century notions of domesticity with twentieth-century notions of tourism. Many critics and biographers of Muir have observed a general shift in his priorities over time, away from an emphasis on the experience of the solitary observer in nature and toward a more lenient understanding of the experience of other humans in the world, both as residents of domestic space and tourists in the wilderness. This paper contributes to recent discussions of the domestic in Muir\u27s writing by Michael Smith, Robert Dorman, and Steven Holmes in its argument that Muir\u27s late writings about Yosemite were not an attempt to camouflage his true beliefs but were rather a reflection of the domesticating influence exerted by both his audience and his family. In particular, I argue that, following his marriage to Louie Strenzel in 1880 and during the years he spent with her and their daughters in Martinez, Muir gradually came to value the domestic--and its touristic counterpart--as an essential element in the preservation of nature through the national parks

A randomized controlled trial to test the efficacy of trans-tympanic injections of a sodium thiosulfate gel to prevent cisplatin-induced ototoxicity in patients with head and neck cancer

Abstract Background Cisplatin-induced hearing loss is frequent and severe. Antioxidants such as sodium thiosulfate (STS) can neutralize the effects of cisplatin. The objective of the trial was to test the efficacy of trans-tympanic injections of a STS gel to prevent cisplatin-induced ototoxicity. Methods Eligible participants were newly diagnosed patients with stage III or IV squamous cell carcinoma of the mouth, oropharynx, hypopharynx, or larynx and scheduled to be treated by concurrent chemoradiation (CCR). Patients with asymmetric hearing were not eligible. The planed treatment included cisplatin 100 mg/m2 at days 1, 22 and 43. A baseline pre-treatment complete audiometric evaluation (pure tone at frequencies ranging from 0.5 to 14 kHz, bone conduction at 0.5–4 kHz and DPOAEs) was performed. Adverse effects were noted according to CTCAE. On the day before the beginning of CCR, eligible and consenting patients were randomized to receive a trans-tympanic injection of the gel either in the left ear or in the right ear. A final post-treatment complete audiometric evaluation was scheduled to be performed 1 month after the end of CCR by audiologists kept blind to the ear assignment. For the main outcome, the permanent threshold shift (PTS) in decibel (dB) was calculated as the difference between the final and baseline measures at all pure tone frequencies at 0.5–14 kHz for each patient and for each ear. The main outcome was assessed blindly in a mixed linear model with the PTS as the dependent variable and intervention, frequency, their interaction and radiation dose to the cochlea as independent variables. Results Between January 2015 and April 2016, 13 patients were randomized. The trial was stopped in June 2016 for poor accrual. The average loss of hearing over all frequencies was 1.3 dB less for treated ears compared to control ears. Although not statistically (p = 0.61) nor clinically significant, the difference was in favor of the treated ears for all frequencies between 3 and 10 kHz. Conclusions Our trial suggests that STS deposited on the round window was safe for the middle and inner ears. More work is needed to improve the efficacy of trans-tympanic injections of cisplatin antidotes. Trial registration ClinicalTrials.gov, NTC02281006, Registered 3 November 2014

Incidence, predictive factors, and prognostic value of new-onset atrial fibrillation following transcatheter aortic valve implantation

Objectives: This study sought to evaluate the incidence, predictive factors, and prognostic value of new-onset atrial fibrillation (NOAF) following transcatheter aortic valve implantation (TAVI). Background: Very few data exist on the occurrence of NOAF following TAVI. Methods: A total of 138 consecutive patients with no prior history of atrial fibrillation (AF) underwent TAVI with a balloon-expandable valve. Patients were on continuous electrocardiogram monitoring until hospital discharge, and NOAF was defined as any episode of AF lasting >30 s. All clinical, echocardiographic, procedural, and follow-up data were prospectively collected. Results: NOAF occurred in 44 patients (31.9%) at a median time of 48 h (interquartile range: 0 to 72 h) following TAVI. The predictive factors of NOAF were left atrial (LA) size (odds ratio [OR]: 1.21 for each increase in 1 mm/m2, 95% confidence interval [CI]: 1.09 to 1.34, p < 0.0001) and transapical approach (OR: 4.08, 95% CI: 1.35 to 12.31, p = 0.019). At 30-day follow-up, NOAF was associated with a higher rate of stroke/systemic embolism (13.6% vs. 3.2%, p = 0.021, p = 0.047 after adjustment for baseline differences between groups), with no differences in mortality rate between groups (NOAF: 9.1%, no-NOAF: 6.4%, p = 0.57). At a median follow-up of 12 months (interquartile range: 5 to 20 months), a total of 27 patients (19.6%) had died, with no differences between the NOAF (15.9%) and no-NOAF (21.3%) groups, p = 0.58. The cumulative rate of stroke and stroke/systemic embolism at follow-up were 13.6% and 15.9%, respectively, in the NOAF group versus 3.2% in the no-NOAF group (p = 0.039, adjusted p = 0.037 for stroke; p = 0.020, adjusted p = 0.023 for stroke/systemic embolism). Conclusions: NOAF occurred in about one-third of the patients with no prior history of AF undergoing TAVI and its incidence was increased in patients with larger LA size and those undergoing transapical TAVI. NOAF was associated with a higher rate of stroke/systemic embolism, but not a higher mortality, at 30 days and at 1-year follow-up