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Rapid diagnosis by using small, simple, and portable devices could represent one of the best strategies to limit the damage and contain the spread of viral, bacterial or protozoa diseases, principally when they can be transmitted by air and are highly contagious, as some respiratory viruses are. The presence of antibodies in blood or serum samples is not the best option for deciding when a person must be quarantined to stop transmission of disease, given that cured patients have antibodies, so the best diagnosis methods rely on the use of nucleic acid amplification procedures. Here we present a very simple device and detection principle, based on paper discs coupled to contactless conductivity (C4D) sensors, can provide fast and easy diagnostics that are needed when an epidemic outbreak develops. The paper device presented here solves one of the main drawbacks that nucleic acid amplification tests have when they are performed outside of central laboratories. As the device is sealed before amplification and integrally disposed in this way, amplimers release cannot occur, allowing repetitive testing in the physician’s practice, ambulances, or other places that are not prepared to avoid cross-contamination of new samples. The use of very low volume samples allows efficient reagent use and the development of low cost, simple, and disposable point-of-care diagnostic systems., Author summary In 2005, the World Health Organization (WHO) recognized Chagas Disease as a neglected tropical disease. Meanwhile the serological tests, recommended by WHO, can be performed for chronic disease diagnosis, the nucleic acid amplification tests must be performed for the detection of the acute phase of the disease. Although the existing laboratory diagnosis tests for Chagas Disease are sensitive and highly reproducible, they cannot be performed in rural, low infrastructure environments, where this disease prevails. In this sense, the use of simple and portable analytical devices may be able to offer an affordable solution to this problem, allowing fast sampling, diagnosis and treatment prescription in one simple and fast intervention, as the performed by short term medical missions. In this study we show for the first time a diagnosis test comprising low cost materials and employing a contactless and label-free conductivity detection system that is used to read the result of a nucleic acid amplification reaction. The test showed high sensitivity for Chagas Disease diagnosis showing the potential to be used in rural and low income places.

Background Reduced susceptibility of mosquito vectors to currently used insecticides hampers control interventions. Recently pyriproxyfen, an insect growth regulator has been demonstrated to effectively reduce the reproductive potential in vector mosquitoes. Methods Pyriproxyfen (PPF), in different concentrations (0.75%, 0.075%, 0.0075%, and 0.00075%) was applied on papers and Indian wild type Aedes aegypti female mosquitoes (N ≥ 20 for each treatment) were exposed onto it as per WHO guidelines, to study the reproductive disruption. PPF concentration on treated papers was quantitatively cross-determined using HPLC method. Reduction in fecundity, fertility and adult emergence in exposed female Ae. aegypti was determined. Abnormal development in ovary and eggs of exposed females was studied microscopically after different time intervals. Results Eggs laid, eggs hatched, pupae formed and adults emerged per female exposed in both before blood meal and after blood meal groups declined significantly from lowest to highest concentration of PPF (F ≥ 5.2; p < 0.02). Adult emergence inhibition in females exposed to PPF before and after blood meal groups ranged from 58.8% [OR = 0.18 (95% CI = 0.09–0.36)] to 79.2% [OR = 0.04 (95% CI = 0.02–0.10)] and 64.4% [OR = 0.12 (95% CI = 0.05–0.28)] to 77.1% [OR = 0.05 (95% CI = 0.02–0.14)] respectively in different concentrations. The probit model used suggested that FI50 (50% fertility inhibition) and EI50 (50% emergence inhibition) were 0.002% (p = 0.82) and 0.0001% (p = 0.99) for females exposed before blood meal, while 0.01% (p = 0.63) and, Author summary Development of resistance against insecticides has challenged mosquito control programmes globally and prompted the research of alternative options that can complement insecticides. An insect growth regulator, pyriproxyfen (PPF) usage against mosquitoes can effectively reduce the vector population. PPF mainly inhibits the metamorphosis of mosquito larvae into pupae and prevent the adult emergence, therefore it is generally applied in mosquito breeding habitats. PPF has been shown to exhibit delayed residual effect that may impair the reproductive capacity by affecting the survival, fecundity and fertility of adult mosquito exposed through tarsal contact. Presently, the effectiveness of different concentrations of PPF intended to be delivered through contact have been evaluated against dengue vector Ae. aegypti. Results suggested that very low PPF concentration treated surfaces drastically reduce the fecundity, fertility and adult emergence in mosquitoes. Study suggests that control interventions based on PPF-treated surfaces could provide an additional route to target mosquito vector control by overall population density reduction.