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Exploring the world of disease vectors in London

| December 22, 2013

In October 2012, the International Society for Neglected Tropical Diseases hosted ISNTD Bites, the  first parasitology and vector-control conference to showcase and discuss major issues surrounding vector evolution and control methods. To continue on the momentum of this event the second ISNTD Bites, a year on, provided emphasis on disease & vector surveillance methods and tools, the growing implications of resistance and a special focus on dengue.

The Ondaatje Theatre at the Royal Geographic Society hosted the main presentations at the ISNTD 2013 event.

The Ondaatje Theatre at the Royal Geographic Society hosted the main presentations at the ISNTD 2013 event.

The Royal Geographic Society on Kensington Gore, London, with its associations to famous explorers such as Livingstone and Shackleton, provided an appropriate venue. Despite travel restrictions caused by the temporary shutdown of the US government and visa restrictions for other speakers, technology was well utilized with overseas contributors able to attend by Skype and some speakers sending their contribution by video.

Professor Simon Hay of the University of Oxford opened proceedings with a presentation on ‘The Global Distribution and Burden of Dengue’

Professor Simon Hay of the University of Oxford opened proceedings with a presentation on ‘The Global Distribution and Burden of Dengue’

There was a full programme of eighteen speakers grouped across four sessions – Epidemiology and Surveillance Technologies; Innovation in Vector Control’, ‘Impact of Insecticide Resistance’ and a ‘Focus on Dengue’. – were supported by workshops on Insect repellents, Fogging, Transgenic mosquitoes and Diagnostics for disease surveillance, although the fogging workshop by IGEBA was later changed to a short presentation. To keep delegates occupied during coffee breaks and lunch, there was a small exhibition and poster area. Any possible shortfall in quantity of delegates was well compensated by the quality of presentations.

Joerg Heckel of IGEBA had to improvise as the Fogging workshop became a shortened presentation.

Joerg Heckel of IGEBA had to improvise as the Fogging workshop became a shortened presentation.

The first session, covering the topic of Epidemiology & Surveillance Technologies included presentations by Dr. Anthony Solomon (London School of Hygiene & Tropical Medicine) who looked at the Global Trachoma Mapping Project;  Dr. Josep Jansa (European Centre for Disease Prevention & Control – ECDC); Dr. Mark Perkins (FIND Diagnostics) – FIND malaria test & malaria and Chagas LAMP projects; Dr. Edward Wright (Viral Pseudotype Unit) – Pseudotyped viruses for emerging and zoonotic infections: a flexible tool for serosurveillance; and Dr. Miguel Luengo-Oroz (MalariaSpot) – Using an online game & crowd sourcing for malaria parasite quantification.

The first parallel Workshop provided a platform to discuss the current situation for skin insect repellents and overlapped in part with Session 1.  Contributions were from Ulla Obermayr – Biogents, James Logan – LSHTM, Vanessa Chen-Hussey – LSHTM and Dr Cameron Webb via Skype at the University Sydney, Australia.  Whilst novel initiatives such as the crowd funded Kite Patch project www.kitepatch.com may be seeking to provide a revolutionary breakthrough, the traditional repellent market is still dominated by DEET, the longest used and relied on mosquito repellent active ingredient, to provide protection for indigenous sufferers.

Despite its long use, repellents are reportedly inefficient in providing protection to wearers due to the lack of spatial protection with mosquitoes able to detect untreated portions of skin. There was also mention of toxicity concerns through continued use although none of this based on scientific evidence.  Despite reference to PMD by contributors from Citrefine, little mention was made of other molecules showing promise and in commercial development including botanicals such as geraniol.

Philip Wege of Syngenta highlighted that the vector control is a very small market compared to crop protection

Philip Wege of Syngenta highlighted that the vector control is a very small market compared to crop protection

Innovation in Vector Control, the title of Session 2, sadly provided little that was innovating in the way of new chemistry. Philip Wege of Syngenta presented the progress of the IVCC Product Development Partnership but was at pains to highlight that, as vector control is a very small market compared to crop protection and the seeds business of agrochemical companies, the lack of new insecticides had been due in part to the changing requirement for crop protection insecticides away from persistent molecules like DDT that had been considered essential for mosquito control using indoor residual spraying and more recently the widespread use of bed nets. Attention to new molecules for vector control has clearly been due to the efforts of the Innovative Vector Control Consortium (IVCC) and the major agrochemical companies to release and screen molecules from company archives.

In a break from insects, David Rollinson turned the spotlight onto disease transmission by molluscs.  He highlighted that the only molluscicide currently in broad use is nicosamide which is toxic to fish that and industry had not been looking or did not have the capability to screen for new mollusc control agents.  One novel project considered the use of river water prawns in Senegal to consume snails. Damming of the Senegal River estuary caused a disease epidemic by making a species of prawn extinct that was the natural predator of the snail responsible for human schistosomiasis.

The goal of “Projet Crevettes” is to restore the prawn through local freerange prawn cultivation, making the positive health benefits sustainable through economic incentive for the rural poor. It was a concern that with despite mass distribution of drugs to treat schistosomiasis, more was needed to be one to reduce the number of snails in areas with the disease. See http://ow.ly/qKi99.

Matt Thomas said that WHO tests were only done with mosquitoes at a constant temperature which did not reflect the real world.

Matt Thomas said that WHO tests were only done with mosquitoes at a constant temperature which did not reflect the real world.

Following from the morning workshop presentation, Dr James Logan looked again at the role of repellents in vector control. Despite many years of use, the mode of action of DEET was still not fully understood and the effect of repellents on disease transmission was unclear.  Research continues, looking at possible leads from examining those who do not naturally get bitten by insects and the use of twins in a repellency testing.

Professor Hemingway revealed that despite academic discussions about resistance management strategies, only two African countries had put in place resistance management plans.

Professor Hemingway revealed that despite academic discussions about resistance management strategies, only two African countries had put in place resistance management plans.

Session 3 covered the Impact of Resistance with presentations by Janet Hemingway – LSTM on behalf of IVCC, Philip Wege – Syngenta, Pr Matt Thomas – Penn State and Helen Pates Jamet – Vestergaard-Frandsen.  Professor Hemingway revealed that despite academic discussions about resistance management strategies, only two African countries had put in place resistance management plans to prolong the effective life of pyrethroids.  This was why the IVCC were driving the pesticide industry to develop new active ingredients or formulations to use in resistance management programmes.  However, with the cost of the most widely used pyrethroids being remarkably low, there is perceived to be a problem of how any new molecules could be used within a resistance management strategy, when they do become available, as they will be more expensive. In Matt Thomas talk, ‘The Impact of Environmental Conditions on vectors’, he said that WHO tests were only done with mosquitoes at a constant temperature which did not reflect the real world. Studies had shown that susceptibility was affected by diurnal changes in temperature.

Dr Helen Pates Jamet presented the IR mapper which provides a downloadable resource to show where resistant mosquitoes can be found.

Dr Helen Pates Jamet presented the IR mapper which provides a downloadable resource to show where resistant mosquitoes can be found.

Looking at insecticide resistance mapping, Dr Helen Pates Jamet presented the IR mapper which provides a downloadable resource to show where resistant mosquitoes can be found – see www.irmapper.com

The final session focused on dengue, which with urbanisation, is becoming more serious than malaria in terms of numbers of people affected.

Patrick Copeland from internet group Google managed to avoid the main topic but presented on the interesting development in the use of algorithms to provide real-time information to people near a crisis: referring to the recent typhoon in India where mapping the path of the typhoon, through internet and mobile technology; enabled people to be alerted, so they could be moved away from danger areas and so helping to reduce loss of life.

Patrick Copeland revealed how internet group Google can provide real-time information to map diseases by analysing keyword searches from internet users.

Patrick Copeland revealed how internet group Google can provide real-time information to map diseases by analysing keyword searches from internet users.

By relating query volume to outbreaks of disease they had initially looked at data on flu but have also selected dengue fever as it is mainly an urban disease. Such is the use of keyword searches on internet sites such as Google, it is possible to map and identify areas where diseases may arise simply by analysing keyword searches from internet users. The paper can be accessed here http://ow.ly/qKdGO.

In the afternoon parallel workshop on ‘Transgenic mosquitoes: Oxitec & Innovative Insect Control’ Dr Andrew McKemey (Technical Development Manager, Oxitec) expanded on the presentation he had given in the plenary session on ‘Innovation in vector control’. He was joined by Hadyn Parry (CEO, Oxitec) and Dr Camilla Beech (Regulatory Manager, Oxitec) to answer questions and discuss the topic with attendees.

Oxitec has clearly run a set of successful trials demonstrating up to 96% suppression of Aedes aegypti and they are now scaling this up with a programme to protect 50,000 people from dengue in Jacobina, a town in North Brazil. Hadyn emphasised the importance of working in partnership with local research organisations, local government and community bodies.

It is difficult to cover every angle in a one day symposium and the organisers did well in putting together a full programme.  Noticable absentees were discussions on the development of larvicides and new developments of potential for biological control products that have featured heavily at other pest management conferences. These may in time provide essential resistance management tools when considering how to cope with pyrethroid resistant insect vectors.

The all day exhibition provided an opportunity for those related to the vector management industry to showcase their products. In addition to those who were presenting or involved in worskshops were VectorFog from Korea (www.vectorfog.com); the London School of Hygiene and Tropical Medicine with information on ARCTEC, the Arthropod Control Product Test Centre (www.arctec.lshtm.ac.uk); and the Liverpool School of Tropical Medicine LITE (Liverpoool Insect Testing) facility (www.lite-testing-facility.com).

Published in International Pest Control – November/December 2013 issue.

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Category: Public health, Special features

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