Eave tubes for malaria control in Africa: a modelling assessment of potential impact on transmission.

BACKGROUND: Novel interventions for malaria control are necessary in the face of problems such as increasing insecticide resistance and residual malaria transmission. One way to assess performance prior to deployment in the field is through mathematical modelling. Modelled here are a range of potential outcomes for eave tubes, a novel mosquito control tool combining house screening and targeted use of insecticides to provide both physical protection and turn the house into a lethal mosquito killing device. METHODS: The effect of eave tubes was modelled by estimating the reduction of infectious mosquito bites relative to no intervention (a transmission metric defined as relative transmission potential, RTP). The model was used to assess how RTP varied with coverage when eave tubes were used as a stand-alone intervention, or in combination with either bed nets (LLINs) or indoor residual spraying (IRS). RESULTS: The model indicated the impact of eave tubes on transmission increases non-linearly as coverage increases, suggesting a community level benefit. For example, based on realistic assumptions, just 30 % coverage resulted in around 70 % reduction in overall RTP (i.e. there was a benefit for those houses without eave tubes). Increasing coverage to around 70 % reduced overall RTP by >90 %. Eave tubes exhibited some redundancy with existing interventions, such that combining interventions within properties did not give reductions in RTP equal to the sum of those provided by deploying each intervention singly. However, combining eave tubes and either LLINs or IRS could be extremely effective if the technologies were deployed in a non-overlapping way. CONCLUSION: Using predictive models to assess the benefit of new technologies has great value, and is especially pertinent prior to conducting expensive, large scale, randomized controlled trials. The current modelling study indicates eave tubes have considerable potential to impact malaria transmission if deployed at scale and can be used effectively with existing tools, especially if they are combined strategically with, for example, IRS and eave tubes targeting different houses.This work was supported by European Union Seventh Framework Programme Grant 306105, FP7-HEALTH-2012-INNOVATION-1

Alterations in mosquito behaviour by malaria parasites: potential impact on force of infection

BACKGROUND: A variety of studies have reported that malaria parasites alter the behaviour of mosquitoes. These behavioural alterations likely increase transmission because they reduce the risk of vector death during parasite development and increase biting after parasites become infectious. METHODS: A mathematical model is used to investigate the potential impact of these behavioural alterations on the lifetime number of infectious bites delivered. The model is used to explore the importance of assumptions about the magnitude and distribution of mortality as well as the importance of extrinsic incubation period and gonotrophic cycle length. Additionally, the model is applied to four datasets taken from actual transmission settings. RESULTS: The impact of behavioural changes on the relative number of lifetime bites is highly dependent on assumptions about the distribution of mortality over the mosquito-feeding cycle. Even using fairly conservative estimates of these parameters and field collected data, the model outputs suggest that altered feeding could easily cause a doubling in the force of infection. CONCLUSIONS: Infection-induced behavioural alterations have their greatest impact on the lifetime number of infectious bites in environments with high feeding-related adult mortality and many pre-infectious feeding cycles. Interventions that increase feeding-associated mortality are predicted to amplify the relative fitness benefits and hence enhance the strength of selection for behavioural alteration.This study was supported by the NIH-NIAID ICEMR award (#U19AI089676-01)

Comparison of Methods for Xenomonitoring in Vectors of Lymphatic Filariasis in Northeastern Tanzania.

Monitoring Wuchereria bancrofti infection in mosquitoes (xenomonitoring) can play an important role in determining when lymphatic filariasis has been eliminated, or in focusing control efforts. As mosquito infection rates can be low, a method for collecting large numbers of mosquitoes is necessary. Gravid traps collected large numbers of Culex quinquefasciatus in Tanzania, and a collection method that targets mosquitoes that have already fed could result in increased sensitivity in detecting W. bancrofti-infected mosquitoes. The aim of this experiment was to test this hypothesis by comparing U.S. Centers for Disease Control and Prevention (CDC) light traps with CDC gravid traps in northeastern Tanzania, where Cx. quinquefasciatus is a vector of lymphatic filariasis. After an initial study where small numbers of mosquitoes were collected, a second study collected 16,316 Cx. quinquefasciatus in 60 gravid trap-nights and 240 light trap-nights. Mosquitoes were pooled and tested for presence of W. bancrofti DNA. Light and gravid traps collected similar numbers of mosquitoes per trap-night, but the physiological status of the mosquitoes was different. The estimated infection rate in mosquitoes collected in light traps was considerably higher than in mosquitoes collected in gravid traps, so light traps can be a useful tool for xenomonitoring work in Tanzania

Nonleptonic Decays and Lifetimes of b-quark and c-quark Hadrons

We review recent experimental results on lifetimes and hadronic decays of hadrons that contain $c$ and $b$ quarks. The theoretical implications of these results are also considered. An understanding of hadronic decays of heavy quarks is required to interpret the CP violating asymmetries in $B$ decays that will be observed in experiments planned for the near future.Comment: 74 pages, LATEX format with 12 figures. To appear in Annual Review of Nuclear and Particle Science, Vol. 46. Also available at http://www-physics.mps.ohio-state.edu/~phys111/b-physics/bphysics.html and by anonymous ftp from ftp://pacific.mps.ohio-state.edu/pub/hepex/kh A serious typographical error on p. 8 is corrected. Other errors and typos are also correcte

The influence of feeding behaviour and temperature on the capacity of mosquitoes to transmit malaria

Insecticide-treated bed nets reduce malaria transmission by limiting contact between mosquito vectors and human hosts when mosquitoes feed during the night. However, malaria vectors can also feed in the early evening and in the morning when people are not protected. Here, we explored how the timing of blood feeding interacts with environmental temperature to influence the capacity of Anopheles mosquitoes to transmit the human malaria parasite Plasmodium falciparum. In laboratory experiments, we found no effect of biting time itself on the proportion of mosquitoes that became infectious (vector competence) at constant temperature. However, when mosquitoes were maintained under more realistic fluctuating temperatures, there was a significant increase in competence for mosquitoes feeding in the evening (18:00), and a significant reduction in competence for those feeding in the morning (06:00), relative to those feeding at midnight (00:00). These effects appear to be due to thermal sensitivity of malaria parasites during the initial stages of parasite development within the mosquito, and the fact that mosquitoes feeding in the evening experience cooling temperatures during the night, whereas mosquitoes feeding in the morning quickly experience warming temperatures that are inhibitory to parasite establishment. A transmission dynamics model illustrates that such differences in competence could have important implications for malaria prevalence, the extent of transmission that persists in the presence of bed nets, and the epidemiological impact of behavioural resistance. These results indicate that the interaction of temperature and feeding behaviour could be a major ecological determinant of the vectorial capacity of malaria mosquitoes

Enhancing communication between academic staff and students to undergraduate degree level with a particular focus on assessment requirements

The way that academic staff make their requirements known to students is varied -for students of Art and Design this is usually a written brief, supplemented with averbal briefing. All assessment in Art and Design is by course work in a variety offormats: written, visual, electronic and spoken. There is a tension betweenencouraging original and creative responses and being over prescriptive whenstipulating assessable work requirements. The criteria on which visual work isassessed are often not clear to students and are sometimes perceived as beingsubjective. Ideas about what constitutes quality in visual work can also be confusedleading to a lack of transparency in the assessment process. Additionally, poorcommunication between staff and students may lead to procedural problems aboutsubmission of work, deadlines and so on. This is especially the case when studentnumbers are high. In addition, as funding models alter the traditional staff - studentrelationship moving it closer to a provider - customer relationship, it becomesimperative that expectations and obligations are made clear for all parties. Largequantities of information have to be made available in an accessible and user-friendlyway. Initial information gathering from students indicates that electroniccommunication including e-mail and text messaging would be both popular andappropriate for some types of communication