Tuesday, September 4, 2012


Female Ae. aegypti. Lateral view

The word "mosquito" originated from the Spanish words "muscato", "muskitto" or "musqueto" to mean "small fly"
Their importance is not known except that they BITE!
- Patrick Mason first discovered that mosquitoes – the Culex quinquefasciatus – can transmit filariasis, a parasitic disease, in 1878
- Ronald Ross discovered the malaria parasite in Anopheline mosquitoes in 1897
- Colonel Walter Wright discovered that Ae. aegypti (Aedes aegypti) can transmit yellow fever in 1900
- The male mosquito is smaller than the female mosquito

Aedes aegypti (Male on the left, Female on the right) Source: Wikipedia

Only female mosquitoes BITE!
Male mosquitoes do not bite or spread disease as they do not have the mouthparts to bite

Diseases transmitted by mosquitoes in Malaysia : There are 5 human diseases transmitted by mosquitoes in Malaysia: Malaria, Dengue, Filariasis, Japanese Encephalitis and Chikungunya.

The mosquito life cycle:

The incidence of dengue in Malaysia has been rising steadily, from 7,103 cases in 2000 to 46,171; including 134 deaths, in 2010 and the disease costs the Malaysian economy between RM270 million and RM667 million per annum. In light of this, the Malaysian government has identified dengue control as a national priority.
Dengue has also put some 2.5 billion people in more than 100 countries at risk.


At present, there is no effective vaccine or specific treatment for dengue fever while current control methods (eg. larviciding, space spraying with insecticides or fogging, public education or ComBI, legally enforced breeding site reduction, etc.) have not stopped the spread of the disease. So there is an urgent need to evaluate promising new technologies.


                                 Source : National Enviroment Agency

2.1. Dengue
Dengue is transmitted by the bite of a female Aedes aegypti mosquito infected with any one of four versions of the dengue virus and the major source, or reservoir, of the virus is humans. The disease is transmitted when a female Aedes aegypti mosquito bites an infected person and then bites someone else. Symptoms appear within 3 – 14 days (average 4 – 7 days).

Classical dengue fever is a severe, flu-like illness that affects infants, young children and adults. Dengue hemorrhagic fever is a potentially lethal complication, particularly in children, and early clinical diagnosis and careful clinical management by experienced physicians and nurses is necessary to reduce the number of fatalities.
More than 70% of the global disease burden is in South-East Asia, Asia and the Western Pacific areas. In Latin America and the Caribbean, the incidence and severity of the disease are increasing rapidly while the USA, Europe and the Eastern Mediterranean are much less affected. International air travel is facilitating the rapid global movement of dengue viruses as it increases the risk of dengue hemorrhagic fever epidemics by introducing new dengue viruses into susceptible populations.

2.2. Chikungunya
Chikungunya is a viral disease. First observed in 1952 in Tanzania, the name comes from the local Swahili dialect which means "that which bend up" for the stooped walk that reflects the physique of a person suffering from the disease.
Chikungunya (also known as chikungunya virus disease or chikungunya fever) is a debilitating but usually non-fatal, viral illness that is spread by the bite of infectedAedes aegypti mosquitoes. Its symptoms can resemble those of dengue fever.
There is no specific treatment for chikungunya either. Supportive therapy that helps ease symptoms; such as non-steroidal anti-inflammatory drugs and getting plenty of rest, may be beneficial.

2.3. Yellow Fever
Also transmitted through the Aedes aegypti mosquito, Yellow Fever displays similar symptoms to that of Dengue and Chikungunya and although not very common in the Asian region, the risk of infection still exists.

The Ministry of Health Malaysia (MoH) has been evaluating a promising technology, called RIDL®, which involves genetically modified Aedes aegypti male mosquitoes. Using genetically-modified male mosquitoes to mate with the local Aedes aegypti mosquitoes means they will not produce offspring that survive adulthood leading to a reduction in the overall Aedes aegypti population. This technique is based on the well-understood and tested concept known as Sterile Insect Technique. By evaluating this technology in a methodical and step-wise manner, the Ministry can assess its potential to be deployed as a long-term solution to controlling dengue.

3.1. How it all started
The genetically-modified Aedes aegypti OX513A mosquito strain (OX513A) was originally developed at the University of Oxford, which founded and part-owns Oxitec, a UK company. Upon the invitation of the MoH, Oxitec transferred its lead strain of Aedes aegypti OX513A to the Institute for Medical Research Malaysia (IMR) for independent evaluation in 2006. Since then, the IMR has successfully evaluated this new control technology under laboratory and semi-field conditions. The technology has also been evaluated by reputed institutes around the world including the Institut Pasteur in Paris, France, and the WHO Collaborating Centre for the Ecology, Taxonomy and Control of Vectors of Malaria, Filariasis & Dengue at the IMR and so far, the results have been very encouraging.
Oxitec's genetically-modified technology is a genetic enhancement of the well established sterile insect technique (SIT). SIT is used in large-scale operational control or eradication programs against insect species of agricultural importance, throughout the world, and is a technique which is well-understood due to operational deployment spanning 50 years. Oxitec's-SIT works by repeatedly releasing large numbers of (genetically) sterile male Ae. aegypti mosquitoes in the area where control is desired. These released sterile males compete with their wild male counterparts for available wild female mating partners. Matings between OX513A sterile males and fertile wild females produce no viable offspring. Successive releases quickly cause a crash in the population level.

On the 20th of December, 2006 the Government of Malaysia and Oxitec signed a Joint Initiative Agreement to undertake an evaluation on the latter's technology in Malaysia. The evaluation was planned to be conducted in three phases:
PHASE 1: Laboratory Studies [ COMPLETED]
PHASE 2: Contained Field Trials [COMPLETED]
PHASE 3: Open Field Release
3(a) MRR in uninhabited area - Bentong [COMPLETED]
3(b) MRR in inhabited area – to be conducted in Alor Gajah, Melaka [To be conducted once all regulatory requirements met]
3(c) Suppression Trial [Currently undergoing institutional review by IMR]
Cayman Islands and Brazil have already initiated Aedes aegypti OX513A open field trials in inhabited areas under their respective local conditions as a potential means to control the spread of dengue.
Link to Nature Biotechnology publication on the study in Cayman Island:
If the Aedes aegypti OX513A is successful in eliminating local populations, then there would be a dramatic reduction in the number of dengue cases and deaths in Malaysia, to the great benefit of not just Malaysia, but other countries that are fighting this same scourge. The technology is not seen as a standalone solution but as part of Integrated Vector Management (IVM), as recommended by the World Health Organisation (WHO).

3.2. The first open trial in Malaysia - limited 'mark-release-recapture' experiment
Permission was received from the National Biosafety Board, Ministry of Natural Resources and Environment (NRE) for a limited mark-release-recapture (MRR) experiment (NRE(S) 609 – 2/1/3) in October 2010. The limited release of approximately 6,000 non-biting sterile male Aedes aegypti mosquitoes from the OX513A strain was carried out on 21 December 2010 in an uninhabited location in Hutan Tanah Kerajaan (Bukan Hutan Simpanan or Non-Reserved Government Forested Land) off Jalan Tentera (off 'Lebuhraya Bentong-Raub') in Daerah Bentong, Pahang, in the presence of representatives from the independent monitor (Akademi Sains Malaysia) and the NRE to ensure compliance with the terms and conditions associated with the approval from the NBB. The release experiment was completed on 5 January 2011 and the area treated twice with insecticide (fogged), as stipulated by the NBB.
The limited mark-release-recapture trial was to study the dispersal and longevity of the Aedes aegypti OX513A mosquitoes in the field and compare them with wild type male Aedes aegypti mosquitoes (which were co-released for comparison), something which could not be ascertained in a laboratory or a contained setting. This in turn, will provide information to the IMR for the risk assessment and risk management of subsequent trials, all of which will be subject to NBB approval.

Following are the chronology of events during the first open release trial in uninhabited area in Bentong, Pahang.
15 December 2010
Mock-run, trial not conducted due to bad weather. Ministry of Natural Resources and Environment (NRE) and independent monitor, Akademi Sains Malaysia (ASM), were present.
21 December 2010
6,045 sterile (GM) males and 5,372 wild (Lab) males released at mid-day in an insular, uninhabited non-reserve forest near Bentong. NRE and independent monitor ASM were both present.
3-5 January 2011
No recaptures, so according to protocol, trial stopped on 5th.
6 & 18 January 2011
Pejabat Kesihatan Bentong conducts fogging as demanded by NBB.
14 February 2011
Weekly ovitrap monitoring (from 7 January 2011) completed.
Photos showing the Limited Mark Release Recapture Study in Uninhabited Area in Bentong, Pahang:

Transporting the male Aedes aegypti (L.) Wild Type
and OX153A strain mosquitoes to the release point

Male mosquitoes were marked using florescent dye



In accordance with NRE guidelines, no further release will be carried out until the post-trial monitoring is completed, and the results analysed and presented in peer-reviewed scientific journals and/or meetings. In parallel, the results will be presented to the independent monitor and the NBB for their review.

3.3. The Next Step – Inhabited 'Mark-Release-Recapture' Experiment
The next step is the inhabited MRR experiment which will also entail the release of approximately 6,000 non-biting sterile male Aedes aegypti mosquitoes but in an inhabited location. Albeit IMR has researched over 50 sites nationwide, timing and location of this next exercise will be dependent on certain scientific requirements; such as the mosquito population dynamics, as well as fulfilling the parameters put forth by the NBB.
3.4. Evaluation & Regulatory Processes
National Biosafety Board and Genetic Modification Advisory Committee
The National Biosafety Board (NBB) and Genetic Modification Advisory Committee (GMAC) were established in May 2010 under the Biosafety Act 2007 by the Ministry of Natural Resources and Environment Malaysia (NRE). One of the areas under the NBB's purview is responsibility for decisions pertaining to the release, importation, exportation and contained use of any living modified organism (LMO) derived from modern biotechnology. The GMAC, on the other hand, is responsible for providing scientific, technical and related advice to the NRE and the NBB.

Approval Process
Application for approval is completed by the applicant and submitted to the Director-General (DG) of NBB together with the prescribed fees, risk assessment and a risk management report, emergency response plan and any other information as may be specified by the NBB.
Upon receipt of the application, the DG refers it to the GMAC and relevant government agencies for their recommendations and invites public participation for the purpose of public disclosure.
The GMAC recommends whether the application should be approved and the terms and conditions to be imposed by the NBB.
After giving due consideration to the GMAC's recommendations, comments of the relevant agencies, views of the public; if any, and any additional information, the NBB then determines whether or not a certificate of approval will be granted.
For further information on the NBB, GMAC or the approval process, visit http://www.biosafety.nre.gov.my

Public Engagement Exercise
The following activities were carried out by IMR and MNRE to inform the public before the MRR trial in Bentong:
A public announcement was issued by MNRE in Berita Harian and New Strait Times on August 5th and 19th 2010. The public announcement message was also simultaneously uploaded onto the Biosafety Department's website (www.biosafety.nre.gov.my).
Due to low turnout of response from the public, the Biosafety Department invited nine Non-Governmental Organizations to provide their comments/response on August 23rd 2010. They were given 30 days to provide their feedback.
The issues raised by the NGOs were analysed and the feedback was published in the Biosafety Department website.

A Question & Answer session with the media was organized by the MNRE on October 29th 2010.
21 members of the media registered at this event. The session was chaired by Mr. Letchumanan Ramatha, Director General of the Biosafety Department of MNRE. Other resource people present were Dr. Ahmad Parveez Hj. Ghulam Kadir (Chair of the Genetic Modification Advisory Committee), Prof. Helen Nair, Assoc. Prof. Dr. Mohd Faiz Foong Abdullah and Dr. Tan Swee Lian (Members of the Committee).
Besides engaging the public at large through media public announcement and public consultation, IMR has also conducted the following briefings or meet the people in Bentong, Pahang. The following sessions were organized:
Briefing to the Bentong Municipal Council members – a briefing was carried out to the members of the Council, chaired by Tuan Jamiri Haji Sainan, Evaluation Officer of the Majlis Perbandaran Bentong on November 1st 2010. The briefing session was attended by IMR and Oxitec representatives and Bentong's Municipal staffs. Dr. Lee Han Lim gave a background presentation on the transgenic Aedes aegypti project and terms & conditions of the approval from the National Biosafety Board. There was a hands-on demonstration of the inability of male mosquitoes to bite, both wild type and transgenic strains. Representatives from Bentong Municipal Council stressed that they supported the project. However, they proposed that all of the stakeholders in Bentong (Bentong Health Office, Bentong District and Land Office and Bentong Police Department) should be invited to meet and discuss the implementation of the project. IMR was asked to find out the ownership of the proposed trial site from the Bentong District and Land Office.
A second briefing was conducted in Majlis Perbandaran Bentong on November 10th 2010, chaired by Tuan Zainal Abidin Bin Md Amin, Secretary of the Majlis Perbandaran Bentong in presence of other government departments including Bentong Health Office and Bentong Land & District Office. All stakeholders and chairman agreed to give their cooperation to IMR by giving all the necessary support letters in order to fulfil the terms and conditions required by NBB. Dr. Lee and Dr. Vasan informed all stakeholders that the exact spot(s) where the transgenic mosquito would be released was located in a government land. IMR requested for approval from the Bentong Municipal. The Chairman agreed and the support letter was faxed to IMR. In addition, since some mosquito traps (BG-Sentinel and ovitrap) were to be placed in a private land adjacent to the trial location, IMR also provided the written consent from the land owner.
Briefing to the Independent Monitor (Akademi Sains Malaysia representative, Dato' Prof. Dr. C.P. Ramachandran) by Dr. Lee and Dr. Vasan was carried out on November 16th 2010.
Based on the NRE guidelines, IMR was requested to display posters announcing the trial in the uninhabited trial sites at least 2 weeks before the beginning of the trial. They were placed on November 30th 2010, 22 days before the release.
The position of the posters were inspected and validated by the NRE representatives, Mr. Onn B. Mohd Jadi and Mr. Mohamad B. Omar, on December 1st 2010.
Briefing to Pahang State Exco Members chaired by the Chief Minister was carried out on December 1st 2010.
A Public briefing on the Limited Mark-Release-Recapture Experiment in uninhabited area in Bentong Pahang was conducted on December 9th 2010. The briefing was carried out in two sessions. The first session was conducted in Bentong Municipal Council Hall in Bahasa Malaysia and English languages while the second session was conducted in Dewan Perhimpunan Cina (Chinese Town Hall, Bentong) in Mandarin.

3.5. The Team
Oxitec Limited was founded in 2002 to develop and commercialise leading-edged science and biotechnology developed at the University of Oxford, United Kingdom. Oxitec has built a broad portfolio of patented technology as well as world-leading expertise in insect molecular biology and regulatory affairs.
In 2010, Oxitec Malaysia Sdn Bhd was established, demonstrating the Company's commitment to helping Malaysia in her dengue control efforts.
Oxitec's approach to insect control via the development of genetic strategies to control disease-carrying mosquitoes has been recognised by leading academics and institutions worldwide. The Company has also received grants from the UK Government to facilitate research and development and is working with the WHO on a project to develop best practices in the deployment of genetic control methods against mosquito disease vectors in disease endemic countries.
For further information on Oxitec, visit http://www.oxitec.com

Institute for Medical Research
The Institute for Medical Research (IMR) began in 1900 with a recommendation from Sir Frank Athelstane Swettenham, Resident–General of the then-Federated Malay States, to establish a Pathological Institute in Malaya to 'carry out scientific and sustained research into the causes, treatment and prevention of such scourges as beri-beri and all forms of malaria fevers.'
In 2001, the IMR restructured into six research and two support centres. Within each of these, scientists from various disciplines collaborate with IMR researchers on priority research projects. This approach and the consolidation of resources have enabled the IMR to venture into growth areas and bring research closer to the cutting edge of science and technology.
For further information on IMR, visit http://www.imr.gov.my/index.php

4. TOP 12 FAQs
1. Why did the Government give its approval for this experiment?
The Aedes aegypti mosquito is the main carrier of dengue, for which there is currently no effective vaccine or specific treatment. The only way to stop dengue is to control the mosquito. As existing control technologies seem unable to stop the spread of dengue and chikungunya, there is an urgent need to evaluate new control technologies.

2. How does the experiment work?
The male Aedes aegypti (OX513A) mosquito strain that was released has a self-limiting genetic element. When female Aedes aegypti mate with the OX513A male mosquitoes, any offspring will die, hence preventing the emergence of the next generation of adult mosquitoes. The released sterile male itself will also die. The strain also contains a fluorescent molecular marker which glows under specific light wavelengths to aid identification between the OX513A and wild Aedes aegyptimosquitoes in the field in the monitoring of trial results.

3. Will this limited release experiment reduce the mosquito population?
No, because the number of sterile male mosquitoes to be released is too small. This will be a first step for larger-scale experiments that may be carried out in future, subject to approvals from the relevant authorities.

4. What if I am bitten by an OX513A mosquito?
Only male Aedes aegypti mosquitoes will be released and male mosquitoes cannot bite. Aedes aegypti mosquitoes also CANNOT mate with any other types of mosquitoes or with any other organisms. It should be noted that this experiment will NOT control wild female mosquitoes that are already in the area. Therefore, if by chance you are bitten by a WILD FEMALE mosquito, treat the bite like you normally would and, if you feel any symptoms such as headache, joint pain, nausea and fever, then immediately consult a doctor for further treatment.

5. You say only sterile male mosquitoes will be released. How can you be so sure? What if a female mosquito is released accidentally?
Great care is taken in the sorting out of the male from the female pupae in the laboratory. It is possible for an experienced person to sort the male pupae from the female as the males are smaller and they have different characteristics. Quality control checks are also carried out in several stages to reduce the possibility of females being included. If however, small numbers of females are released, they will die. Even if they potentially mate, the offspring will die as larvae.

6. What happens once the sterile male mosquitoes are released?
The Aedes aegypti is a relatively short-living mosquito. Adult males can live around 10 days or so in the environment. In the laboratory, under ideal conditions, they can live a bit longer and in extreme cases, up to a month. Once the sterile male mosquitoes have mated with the wild female Aedes aegypti, any offspring will die. The average time the released males lived in this experiment was between 2-3 days.

7. Should we be doing anything different while the experiment is taking place eg. stay indoors, etc?
You should go about your lives as normal. The experiment is only taking place for two days, with four releases (one in the morning and one at night) in total and this process will not interrupt your daily routine.
We however, seek your cooperation with the IMR’s field officers to allow them to place the ovitraps or adult traps and to collect them from your premises.

8. Can we still use insecticide (Ridsect) during the trial period?
You can if you want to. However, we prefer if no insecticide is used during the trial period as this will allow us to obtain a more accurate statistics on the reduction of theAedes aegypti mosquito population.

9. Was the mark-release-recapture trial the first of its kind in the world?

No. The Cayman Islands Mosquito Research and Control Unit has successfully used this technology in open field trials since 2009 and similar (open field) trials are ongoing in Brazil.
The US Department of Agriculture has also been conducting open field trials of a living modified strain for the Pink Bollworm (Pectinophora gossypiella), a moth that is a pest of cotton, since 2006. In 2008, over 15 million modified moths were released aerially in one experiment. These trials and the living modified moths performed exactly as predicted and no negative outcomes of any type (whether environmental, agricultural or to human health) were observed.

10. How was the site for the first test selected? Does this mean the locations chosen are breeding grounds for Aedes aegypti?
The IMR has been carrying out fieldwork at a number of places to study and collect the necessary data and to carefully evaluate potential sites for open field trials. The defined criteria; such as scientific, regulatory, social and ethical, have to be taken into consideration before a site is selected. The criteria include:
i.                    Presence of Aedes aegypti mosquitoes
ii.                  A stable population of Aedes aegypti mosquitoes
iii.                Size of the trial site can demonstrate the accuracy of the trial results
iv.                An isolated site that reduces the possibility of incoming Aedes aegypti mosquitoes from surrounding areas
v.                  Logistics ie, not too far from the IMR laboratory in Kuala Lumpur

11. What are the likely impacts on the environment and humans when releasing GM mosquitoes?
Aedes aegypti is not a native insect to Malaysia and only achieved pan-tropical distribution in the 1930s. It is an urban and semi-urban mosquito which prefers to live around humans. As there are no birds, fish or other insects that feed exclusively on it and there are other mosquito species they can eat, reducing the number of Aedes aegypti is not likely to have any impact on the environment. Additionally, the released mosquitoes will die in the environment and their progeny will die so this is a 'self-limiting' approach ie, there is no permanent change to the wild mosquito population.
The main impact will be to reduce the number of Aedes aegypti females that bite and spread disease. There is no threat to humans as the mosquitoes that are released are all males and males do not bite or spread disease.

12. How do we know if our homes are breeding grounds or not and how can we stop this?
Aedes aegypti breed in clear, stagnant water in containers – not dirty water in drains (longkang), river, stream, etc. – and they breed both outdoors and indoors. You can help control Aedes aegypti by removing their breeding sites by:
i.                    Checking roof gutters and apron drains for blockages regularly
ii.                  Removing water from pot plant plates
iii.                Keeping toys and canvas sheets under shelter
iv.                Changing the water in vases regularly and scrubbing the insides of the vases before refilling with fresh water
v.                  Fitting gully traps with anti-mosquito valves
If everyone plays their role in helping wipe out the places where Aedes aegypti mosquitoes breed, this, combined with Integrated Vector Management, will go some way towards helping control the spread of dengue in Malaysia.

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