PakMediNet Discussion Forum : Medical Research in Pakistan : Dengue control
Dengue control
How should we deal with dengue in swat and the rest of the country?
Dr Ijaz Ali
ijazcas@gmail.com
Daily Times, 18 september 2013
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Back in 2011, I wrote about the consequences of misdirected efforts of the government to tackle dengue and predicted more outbreaks in future. Now, as a consequence of lacking any scientifically devised strategy to curb dengue, we are suffering from another outbreak in Swat. It is surely not going to stop and in the days to come, dengue will not only hit back in the same areas but may also spread to other areas. The government of KPK does not seem to understand the gravity of the situation and just as it happened in the past, cosmetic measures would cost us more lives in future.
Efforts of the government are almost entirely focused on strengthening treatment and diagnostics for a disease with no specific cure or vaccine available, while the role of the mosquito, which is the root cause of infecting people, has drawn little attention in our country. It means that the burden of infection may increase over time as the mosquito is free to breed and infect more people. Just like man, the Aedes mosquitoes are active during the day time and prefer fresh water reservoirs for breeding. Experts of the public sector are advising people to use mosquito nets for protection during the night which indicates their lack of awareness about the Aedes mosquitoes and their seriousness to deal with it. Tree trunks, axils, tyres, water tanks and fresh water pools are sites where the mosquito loves to breed. The mosquito can not travel even a distance of 10 km and these are the infected eggs which carry this infection from place to place. Transportation from the endemic areas, air travel, unplanned urbanization, poor sanitation, poor agricultural practices and environmental degradation are risk factors for the spread of dengue across a region. The infected eggs can survive in the environment for longer periods of time and develop into infected mosquitoes whenever climatic conditions favor their growth. Although one can observe climatic changes in Swat as result of environmental fragmentation, this particular outbreak over there indicates that the mosquito has adopted itself to relatively temperate conditions which is something very alarming for the people of the area where there are numerous fresh water reservoirs, orchards and forests.
We investigated the 2011 outbreak in Lahore which revealed that all the four known serotypes of the dengue virus were prevalent with abundance of serotype 2 and 3. Analysis of blood samples from the infected people in Swat indicated that the same serotype 2 and serotype 3 of the dengue virus are highly prevalent there which means that the current outbreak is a continuation of the previous major outbreak in Lahore. The only difference is the mortality rate which has been comparatively lower in Swat because of the fact that majority of the people have been infected for the first time. Infact, it is the secondary infection of dengue with a virus type different from the one that caused primary infection which leads to fatal consequences for an individual in the form of dengue hemorrhagic fever, dengue shock syndrome or death. The scale of this outbreak is getting larger as thousands of people have been infected so far and another outbreak of dengue in future could be devastating because the mortality rate may rise as a result of secondary infection. If somebody is infected once, secondary infection during his life time could develop into hemorrhagic fever and shock syndrome.
The government should consult competent entomologists and biologists so as to devise an effective mosquito eradication strategy based upon the published scientific literature on eradication programs in other countries. Of course, there are short term and long term options and both of them should be taken into consideration. I suggest that in order to bring about temporary relief, WHO recommended insecticides such as Temephos, Permethrin and Pyroproxyfen should be used alongwith biological agents such as Bti (: Bacillus thuringiensis var. israelensis) or Bs (Bacillus Sphaericus )toxins to target the breeding sites of the mosquito and to disinfect vehicles coming out of the endemic region. Combination of chemical and biological agents have proved to be very effective in killing the mosquito at various stages of its life cycle in a number of countries including , Brazil, Vietnam and Indonesia. Bti is available both in liquid and granular form and various formulations of Bti including Bti tablets for water pools/tanks are also on the market. On long term basis, we should focus on using other biological options (in combination with the use of safe insecticides and Bti/Bs toxins) such as copepods, local fish species, fungi or mosquitoes transformed with Wolbachia (a bacterium) or Densonucleosis viruses. The latter two options are also very effective and have been used in Australia to transform the mosquito population of entire towns. Mosquitoes infected with wolbachia at the germ line level have the capability to replace the wild type in the wild. Mosquitoes transformed with the bacterium or the virus mentioned above have a short life cycle and die before they are capable to transmit the dengue virus to human population. The Aedes mosquitoes have the potential to transmit yellow fever virus or other flavi viruses as well. A proper mosquito eradication strategy is therefore the need of the hour and the government should shift their focus from strengthening treatment and diagnostics only as these can never prevent the spread of infection and would cause a lot of harm in future. It is high time we start believing in science in order to protect ourselves from deadly pathogens at least.
Ijaz Ali, PhD
Head Division of Health Biotechnology
Institute of Biotechnology and Genetic Engineering Peshawar
KP-Agricultural University
0092-331-9378337
Posted by: Drijazali Posts: 3 :: 25-09-2013 :: | Reply to this Message
Re: Dengue control
It is known that Dengue virus have four serotypes,These have 65% homology,So the antobody produced against one serotypes can also act against another serotypes which lead to the uncontrollable excitation of immune system.A huge amount of histamine , Heparin and lequtrine are released which act on blood vessels and increased its permeability.As a result Dengue hemorrhagic and Dengue shock syndrome are develop.In Swat Serotyp2 and serotyp3 are involved in Dengue infection.The people who have infected and recovered from dengue are at risk for secondary infection. they should to take preventive measures to protect themselves from secondary infection.
Malik jan Microbiologist(M.phil),Post Graduate diploma in medical entomology and disease vectors control.
Health Services Accadmey Islamabad
malikjan17@yahoo.com
[Edited by malikjan17 on 13-11-2013 at 06:09 PM GMT]
Posted by: malikjan17 Posts: 3 :: 13-11-2013 :: | Reply to this Message
Re: Dengue control
It is known that Dengue virus have four serotypes,These have 65% homology,So the antobody produced against one serotypes can also act against another serotypes which lead to the uncontrollable excitation of immune system.A huge amount of histamine , Heparin and lequtrine are released which act on blood vessels and increased its permeability.As a result Dengue hemorrhagic and Dengue shock syndrome are develop.In Swat Serotyp2 and serotyp3 are involved in Dengue infection.The people who have infected and recovered from dengue are at risk for secondary infection. they should to take preventive measures to protect themselves from secondary infection.
Malik jan Microbiologist(M.phil),Post Graduate diploma in medical entomology and disease vectors control.
Health Services Accadmey Islamabad
malikjan17@yahoo.com
Posted by: malikjan17 Posts: 3 :: 13-11-2013 :: | Reply to this Message