Impacts of fluorescent powders on survival of different age cohorts, blood-feeding success, and tethered flight speed of Aedes aegypti (Diptera: Culicidae) females.

Fluorescent powders are one of the most common external markers used to study mosquito behavior and ecology. For their reliable and practical use, it is important to evaluate their effect on biological parameters such as survival, blood-feeding, and mobility. We evaluated the effect of five different fluorescent powders (Day-Glo ® ECO Series) on the survival of different age cohorts, blood-feeding success, and tethered flight speed on Aedes aegypti (Linnaeus) adult females. For survival analysis, three cohorts (2-5, 6-9 and 10-13 days old) were marked and mortality recorded until all died. To examine the effect of fluorescent powders on female response to blood-feeding, the proportions of unfed, partially fed, and fully engorged females, after being exposed to host blood under two different time sets (20 and 40 min.), were compared. Their impact on female tethered flight speed was evaluated recording their flight for 30 min. with a flight mill. Survival distributions between treatments were not significantly different within each cohort. Blood-feeding was not significantly different among marked or unmarked females at both times of blood exposure, with the exception of Signal Green-ECO 18 and Ultra Violet- ECO 20 (at 20 and 40 min.), in which a higher proportion of partially fed females was observed compared to control females. In relation to flight performance, no statistically significant difference in mean tethered flight speed (m/s), among marked and unmarked mosquito groups, was observed. Our results indicate that the tested powders and application method have few significant impacts on Ae. aegypti survival, blood-feeding success and flight performance, and are thus suitable for investigations of mosquito biology in the environment.

Detection of Fluorescent Powders and Their Effect on Survival and Recapture of Aedes aegypti (Diptera: Culicidae).

The use of insect markers, such as fluorescent powders, is a useful tool for studying ecological and epidemiological questions. Evaluating their effect on vectors of human disease agents, such as the invasive mosquito vector Aedes aegypti (Linnaeus), is crucial for their practical and reliable use, especially in parameters linked to the risk of disease transmission such as adult survival, dispersal, and host-seeking. Seven fluorescent powders (Hercules Radiant, DayGlo (DG), Risk Reactor (RR), and Angstrom Technologies), applied externally on cohorts of Ae. aegypti female mosquitoes, were tested to determine their impact on survival and recapture by baited mosquito traps, and their detectability after being exposed to controlled laboratory and semifield environments. There were no significant differences in survival among marked and unmarked females across all powders. Marked females were significantly less likely to be captured in baited traps relative to unmarked females, except for one of the DG powders. All females remained visibly marked on five parts of their body for 30 d (under both environments), except for one of the RR powders. The tested powders and application method are suitable for tracking mosquitoes throughout most of their lives under different environments, without significantly affecting their survival, but with potential impact on recapture by baited traps, possibly due to effects on senses or other physiological traits.

Times to key events in Zika virus infection and implications for blood donation: a systematic review.

OBJECTIVE: To estimate the timing of key events in the natural history of Zika virus infection. METHODS: In February 2016, we searched PubMed, Scopus and the Web of Science for publications containing the term Zika. By pooling data, we estimated the incubation period, the time to seroconversion and the duration of viral shedding. We estimated the risk of Zika virus contaminated blood donations. FINDINGS: We identified 20 articles on 25 patients with Zika virus infection. The median incubation period for the infection was estimated to be 5.9 days (95% credible interval, CrI: 4.4-7.6), with 95% of people who developed symptoms doing so within 11.2 days (95% CrI: 7.6-18.0) after infection. On average, seroconversion occurred 9.1 days (95% CrI: 7.0-11.6) after infection. The virus was detectable in blood for 9.9 days (95% CrI: 6.9-21.4) on average. Without screening, the estimated risk that a blood donation would come from an infected individual increased by approximately 1 in 10 000 for every 1 per 100 000 person-days increase in the incidence of Zika virus infection. Symptom-based screening may reduce this rate by 7% (relative risk, RR: 0.93; 95% CrI: 0.89-0.99) and antibody screening, by 29% (RR: 0.71; 95% CrI: 0.28-0.88). CONCLUSION: Neither symptom- nor antibody-based screening for Zika virus infection substantially reduced the risk that blood donations would be contaminated by the virus. Polymerase chain reaction testing should be considered for identifying blood safe for use in pregnant women in high-incidence areas.

Enhancing disease surveillance with novel data streams: challenges and opportunities.

Novel data streams (NDS), such as web search data or social media updates, hold promise for enhancing the capabilities of public health surveillance. In this paper, we outline a conceptual framework for integrating NDS into current public health surveillance. Our approach focuses on two key questions: What are the opportunities for using NDS and what are the minimal tests of validity and utility that must be applied when using NDS? Identifying these opportunities will necessitate the involvement of public health authorities and an appreciation of the diversity of objectives and scales across agencies at different levels (local, state, national, international). We present the case that clearly articulating surveillance objectives and systematically evaluating NDS and comparing the performance of NDS to existing surveillance data and alternative NDS data is critical and has not sufficiently been addressed in many applications of NDS currently in the literature.

[An international collaborative study on influenza viruses antibody titers and contact patterns of individuals in rural and urban household of Guangzhou].

OBJECTIVE: To describe the influenza viruses antibody levels and contact patterns of individuals in rural and urban regions of Guangzhou and to understand how contact patterns and other factors would correlate with the levels on the titers of antibody. METHODS: "Google Map" was used to randomly select the study points from the administrative areas in Guangzhou region. Each participant was required to provide 5 ml blood serum sample to be tested against different strains of H1N1 and H3N2 influenza viruses. RESULTS: 1) Using "Google map", 50 study points were selected but only 40 study points would meet the inclusion criteria. The cohort of this study consisted 856 households with 2 801 individuals. 1 821 participants (65% of the total number individuals in the cohort) completed the questionnaires. Among the 1 821 participants, 77.3% (1 407/1 821) and 22.7% (414/1 821) of them were from rural and urban areas respectively. There were more male participants in the rural but more female participants in the urban regions. Majority of the participants were from age group 18-59 followed by group 60 with aged 2-17 the least, in both rural and urban areas. 2) 78.1% (1 423/1 821) of the participants provided their serum samples. There appeared a strong correlation between age of the participants and the strength of their antibodies against that strain when a strain first circulated. In particular, seroprevalence was the highest at the age group 2-17. 3) 'Contact' was defined as persons having physical touch or/and conversation within one meter with the participants. Participants reported all having had large number of contacts. The proportion of participants having contacts with ten persons or above was the highest, ranging from 49.8% to 72.6%, particularly in age group 6-17. Compared to weekdays, participants had fewer contact persons on weekends. CONCLUSION: There was a strong correlation between the age of participants at the time when the strains first circulated and the seroprevalence against influenza virus strains of H1N1 and H3N2. Also, age of the participants and the frequencies of their contacts to people, was also correlated.