Infection with tungiasis through interhost movement of adult female sand fleas, Tunga penetrans.
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ABSTRACT:
SUBMITTER: Elson L
PROVIDER: S-EPMC7613320 | biostudies-literature | 2022 Feb
REPOSITORIES: biostudies-literature
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Infection with tungiasis through interhost movement of adult female sand fleas, Tunga penetrans.
Elson Lynne L Thielecke Marlene M Fillinger Ulrike U Feldmeier Hermann H
Transactions of the Royal Society of Tropical Medicine and Hygiene 20220201 2
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Project description:BackgroundThe sand flea, Tunga penetrans, is the cause of a severely neglected parasitic skin disease (tungiasis) in the tropics and has received little attention from entomologists to understand its transmission ecology. Like all fleas, T. penetrans has environmental off-host stages presenting a constant source of reinfection. We adapted the Berlese-Tullgren funnel method using heat from light bulbs to extract off-host stages from soil samples to identify the major development sites within rural households in Kenya and Uganda.Methods and findingsSimple, low-cost units of multiple funnels were designed to allow the extraction of >60 soil samples in parallel. We calibrated the method by investigating the impact of different bulb wattage and extraction time on resulting abundance and quality of off-host stages. A cross-sectional field survey was conducted in 49 tungiasis affected households. A total of 238 soil samples from indoor and outdoor living spaces were collected and extracted. Associations between environmental factors, household member infection status and the presence and abundance of off-host stages in the soil samples were explored using generalized models. The impact of heat (bulb wattage) and time (hours) on the efficiency of extraction was demonstrated and, through a stepwise approach, standard operating conditions defined that consistently resulted in the recovery of 75% (95% CI 63-85%) of all present off-host stages from any given soil sample. To extract off-host stages alive, potentially for consecutive laboratory bioassays, a low wattage (15-25 W) and short extraction time (4 h) will be required. The odds of finding off-host stages in indoor samples were 3.7-fold higher than in outdoor samples (95% CI 1.8-7.7). For every one larva outdoors, four (95% CI 1.3-12.7) larvae were found indoors. We collected 67% of all off-host specimen from indoor sleeping locations and the presence of off-host stages in these locations was strongly associated with an infected person sleeping in the room (OR 10.5 95% CI 3.6-28.4).ConclusionThe indoor sleeping areas are the transmission hotspots for tungiasis in rural homes in Kenya and Uganda and can be targeted for disease control and prevention measures. The soil extraction methods can be used as a simple tool for monitoring direct impact of such interventions.
| S-EPMC10906885 | biostudies-literature
Project description:Camouflage is perhaps the most widespread anti-predator strategy in nature, found in numerous animal groups. A long-standing prediction is that individuals should have camouflage tuned to the visual backgrounds where they live. However, while several studies have demonstrated phenotype-environment associations, few have directly shown that this confers an improvement in camouflage, particularly with respect to predator vision. Here, we show that an intertidal crustacean, the sand flea (Hippa testudinaria), has coloration tuned to the different substrates on which it occurs when viewed by potential avian predators. Individual sand fleas from a small, oceanic island (Ascension) matched the colour and luminance of their own beaches more closely than neighbouring beaches to a model of avian vision. Based on past work, this phenotype-environment matching is likely to be driven through ontogenetic changes rather than genetic adaptation. Our work provides some of the first direct evidence that animal coloration is tuned to provide camouflage to prospective predators against a range of visual backgrounds, in a population of animals occurring over a small geographical range.
| S-EPMC4571681 | biostudies-literature
Project description:BackgroundTunga penetrans, also known as sand flea, causes Tungiasis in humans and animals. Despite its notoriety as an entomological problem, however, the ectoparasite receives little consideration from public health professionals. It is against this background that this article aims to assess the prevalence of and factors associated with Tunga penetrans infestation among 5-14-year-olds in rural Western Ethiopia.MethodsFrom November to December 2020, 487 children aged 5 to 14 were selected from four primary schools in a cross-sectional study using systematic random sampling. Clinical exams, Interviews with parents/guardians and observations of the housing and classroom environments were used to collect data. Descriptive statistics and multivariable regression were used to characterize the data and identify factors associated with Tunga penetrans infestation.ResultTunga penetrans infestation (Tungiasis) was diagnosed in 138 of the 487 children examined, placing the prevalence at 28.3% (95% CI: 24.2%, 32.2%). Mud plastered walls [AOR: 5.83, % CI (3.44-9.88)], having cats in the house [AOR: 5.91, 95% CI (3.51-10.11)], not having separated sleeping quarters for animals [AOR: 4.60, 95% CI (2.69-7.86)], using self-supplied water [AOR: 6.30, 95% CI (3.33-11.93)], walking>30 minutes to school [AOR: 2.37, 95% CI (1.48-3.80)] were associated with Tungiasis.ConclusionIn one way or another, several of the identified factors were linked to poverty. Improved house wall materials, fumigation of mud-plastered houses, dusting or spraying insecticides on domestic animals (such as cats), improved access to water, community education about keeping animals separated from living spaces, and hygiene promotion are all needed, with a focus on locally available, low-cost technologies that the poorest families can afford.
| S-EPMC8555830 | biostudies-literature
Project description:BackgroundTungiasis is a neglected tropical disease which is common in impoverished communities. In sub-Saharan Africa, it is caused by female sand fleas, Tunga penetrans, and pigs are amongst the major domestic animal reservoirs. Depending on the environment, tungiasis occurs throughout the year or preferentially in the dry seasons. This study investigated changes in sand flea abundance and associated morbidity in pigs during a dry season.MethodsTunga penetrans lesions were counted and staged in 35 pigs amongst 22 households with at least one affected pig. Five weekly examinations were performed per animal during a dry season. Enrolment of pigs into the study lasted 17 days and examination was performed for 43 days. The severity score for acute pig tungiasis (SSAPT) was determined for each visit. Generalised linear mixed models (GLMM) were fitted on an absolute time scale to understand factors influencing the changes in abundance of sand flea lesions and SSAPT.ResultsThe prevalence/abundance of tungiasis-associated lesions increased from 57.1%/median 1 lesion at baseline to 71.4%/median 11 lesions after 4 weeks. In parallel, the median SSAPT increased from zero to six. The GLMM analyses fitting negative binomial models to the lesion numbers revealed that time had a linear and a quadratic effect for the viable stages 2 and 3a, and all viable sand flea stages in general with maximal abundance of sand fleas on days 17-18, 33 and 35 from the beginning of the study, respectively. The model for the total number of sand flea lesions, which included dead and excoriated sand fleas, showed the same trend but the peak was not reached within the study period. The number of stage 3b lesions was unexpectedly low. The SSAPT increased linearly over time and was highly dependent on the initial number of sand fleas at enrolment.ConclusionsThere were increasing intensities of sand fleas and SSAPT in domestic pigs during the dry season. The ensuing environmental contamination by off-host stages of T. penetrans increases the risk of transmission to other susceptible hosts, including humans.
| S-EPMC11843770 | biostudies-literature
Project description:The sand flea Tunga penetrans is one of the zoonotic agents of tungiasis, a parasitic skin disease of humans and animals. The dog is one of its main reservoirs. This negatively controlled, randomized, double-masked clinical trial evaluated the therapeutic and residual efficacy of fluralaner for treatment of dogs naturally infested with T. penetrans. Sixty-two dogs from an endemically affected community in Brazil were randomly assigned to either receive oral fluralaner (Bravecto chewable tablets) at a dose of 25 to 56 mg fluralaner/kg body weight, or no treatment (31 dogs per group). Dogs were clinically examined using a severity score for acute canine tungiasis (SCADT), parasitological examinations as defined by the Fortaleza classification, and pictures of lesions on days 0 (inclusion and treatment), 7 ± 2, 14 ± 2, 21 ± 2, 28 ± 2, 60 ± 7, 90 ± 7, 120 ± 7 and 150 ± 7. The percentage of parasite-free dogs after treatment was >90% between days 14 and 90 post-treatment with 100% efficacy on study days 21, 28 and 60. Sand flea counts on fluralaner treated dogs were significantly lower (p<0.025) than control dogs on all counts from day 7 to 120. The number of live sand fleas on treated dogs was reduced by > 90% on day 7, > 95% on days 14 and 90, and 100% from day 21 to 60, and with a significant difference between groups from day 7 to 120. From day 7 to day 120, mean SCADT scores were significantly reduced in treated dogs with a mean of 0.10 compared to 1.54 on day 120 in untreated dogs. Therefore, a single oral fluralaner administration is effective for treating and achieving long lasting (> 12 weeks) prevention for tungiasis in dogs.
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Project description:Northern elephant seals (Mirounga angustirostris) have been integral to the development and progress of biologging technology and movement data analysis, which continue to improve our understanding of this and other species. Adult female elephant seals at Año Nuevo Reserve and other colonies along the west coast of North America were tracked annually from 2004 to 2020, resulting in a total of 653 instrument deployments. This paper outlines the compilation and curation process of these high-resolution diving and location data, now accessible in two Dryad repositories. The code used for data processing alongside the corresponding workflow is available through GitHub and Zenodo. This data set represents 3,844,927 dives and 596,815 locations collected from 475 individual seals with 178 repeat samplings over 17 years. We anticipate that these data will stimulate further analysis and investigation into elephant seal biology and aid in developing new analytical approaches for large marine predators.
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Project description:Gonadal steroids and gender are risk factors for sleep disruptions and insomnia in women. However, the relationship between ovarian steroids and sleep is poorly understood. In rodent models, estradiol (E2) suppresses sleep in females suggesting that E2 may reduce homeostatic sleep need. The current study investigates whether E2 decreases sleep need and the potential mechanisms that govern E2 suppression of sleep. Our previous findings suggest that the median preoptic nucleus (MnPO) is a key nexus for E2 action on sleep. Using behavioral, neurochemical, and pharmacological approaches, we tested whether (1) E2 influenced the sleep homeostat and (2) E2 influenced adenosine signaling in the MnPO of adult female rats. In both unrestricted baseline sleep and recovery sleep from 6-h sleep deprivation, E2 significantly reduced nonrapid eye movement (NREM) sleep-delta power, NREM-slow wave activity (NREM-SWA, 0.5-4.0 Hz), and NREM-delta energy suggesting that E2 decreases homeostatic sleep need. However, coordinated with E2-induced changes in physiological markers of homeostatic sleep was a marked increase in MnPO extracellular adenosine (a molecular marker of homeostatic sleep need) during unrestricted and recovery sleep in E2-treated but not oil control animals. While these results seemed contradictory, systemically administered E2 blocked the ability of CGS-21680 (adenosine A2A receptor agonist) microinjected into the MnPO to increase NREM sleep suggesting that E2 may block adenosine signaling. Together, these findings provide evidence that E2 may attenuate the local effects of the A2A receptors in the MnPO, which in turn may underlie estrogenic suppression of sleep behavior as well as changes in homeostatic sleep need.
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Project description:Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand particle saltation. In this paper, we propose a numerical model for the coupling effect between wind flow and saltating sand particles to simulate wind-blown sand movement over the slope surface and use the SIMPLE algorithm to calculate wind flow and simulate sands transport by tracking sand particle trajectories. We furthermore compare the result of numerical simulation with wind tunnel experiments. These results prove that sand particles have obvious effect on wind flow, especially that over the leeward slope. This study is a preliminary study on windblown sand movement in a complex terrain, and is of significance in the control of dust storms and land desertification.
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