WHO’D HAVE GUESSED! Tyre puncture shops linked to dengue outbreaks

As winter is coming to an end, the threat of a dengue fever outbreak looms once more in the country. Already, 83 new unconfirmed dengue cases have emerged in Punjab and it is being predicted that the situation this time would be worse due to the change in the genetic makeup of the mosquitoes.
A research was conducted to ascertain why the population of dengue vector mosquitoes is continuously increasing in Karachi despite continuous sprays by the authorities concerned.
The confirmed dengue fever and yellow fever vector mosquitoes are Aedes aegypti L. and Aedes albopictus. These two species are of global distribution. Beside these two species in Pakistan, other species of Aedes are also reported.
A quantitative mosquito survey of seven villages in Punjab reported a survey report of Aedes from Karachi city but not from the Thatta district. The WHO reported that by 1980, the distribution of Aedes was limited to the southeastern parts of Sindh.
Dengue was first reported in 1953, but in Pakistan its first case was recorded in 1994, and about 1,000 people were affected. Dengue cases were reported in September-November, 1995 in Lasbela in Balochistan that is about 40 kilometres away from Karachi and 1,800 people were affected in Pakistan that year.
Among them, 34 cases were examined and 15 samples were found positive for dengue. It was expected that the source of dengue mosquitoes introduced into Landi Kotal in Khyber Pakhtunkhwa was most likely Karachi, through imported tyre transportation by sea.
Five regions of Karachi were surveyed, the literature was searched and the results were concluded from the observations collected during the survey visits. Following the theory about the transportation of Aedes aegypti by means of imported tyres, puncture shops in the five regions were investigated, for the presence of Aedes aegypti larvae in the water, stored by them. These regions were:
1. Malir Gulistan-e-Jauhar, Gulzar-e-Hijri, Gulshan-e-Maymar Society and Taiser Town, Saadi Town and Landhi (Cattle Colony).
2. East Landhi (2-6), Korangi (Nasir Colony), Shah Faisal Colony, Gulshan-e-Iqbal and Bahadurabad.
3. West Gulbahar, Liaquatabad, Azizabad, Karimabad, Federal B Area, North Nazimabad (Taimuria), New Karachi and Surjani Town.
4. South Karachi Cantt, Defence Society, Gizri, Clifton and Lee Market.
5. Central Orangi Town, Baldia Town (SCH-29), Metroville-1, Hawkesbay (SCH-42) and Gulshan-e-Bihar.
These regions were found positive for the presence of the dengue vector mosquito, Aedes aegypti as well as for malarial vector mosquitoes Anopheles stephensi and Anopheles subpictus. The population of Culex spp was also found in all five regions.
In each region, 100 tyre puncture shops were frequently visited the whole year.
During the survey, it was observed that:
(i) The Aedes larvae were found in the water stored at the shops in which punctures in the tube are searched.
(ii) The Aedes presence probability chance increased when water was stored for more time i.e. three to six days.
(iii) Eggs, larvae and pupae were found in containers at the shops, where the water was kept for more than a week.
(iv) Eggs, larvae and pupae were found in containers where water was stored for a long time, without emptying the container, and more water was added to it.
(v) Eggs, larvae and pupae were found in big and permanent containers made of plastic, rubber (as tractor tyres after cutting into two or three pieces are used as water container at the puncture shops) and cement tanks.
(vi) Eggs, larvae and pupae were found at shops, where the container was permanent and kept in the shadow of a tree.
(vii) Eggs, larvae and pupae of Aedes were not found in containers, which were emptied daily or the water was changed at least twice a week.
(viii) Normally the eggs, larvae and pupae of Aedes were not found at the shops that were in the boundaries of fuel stations, but only in a very few and rare cases.
(ix) All four stages of the Aedes life cycle were found at sunset timing i.e. the eggs, larvae, pupae and the adults flying near or over the water container. The male female mating of the Aedes mosquitoes with newer emerging female and previously emerged was also noted and observed at the time of sunset.
(x) The containers painted with oil paint, including iron tubs, were not found positive for Aedes mosquito larvae.
It was noted that the dengue vector mosquitoes are continuously increasing because permanent containers at tyre puncture shops, having Aedes eggs, larvae and pupae, serve as permanent Aedes adult adder for the environment and hundreds of pupae per container are emerging into adults on a daily basis.
According to a general and simple calculation, if there are 500 tyre puncture shops in one region of Karachi and only 10 percent (50 shops) are reservoirs, containing Aedes eggs, larvae and pupae, and only 20 adults are coming out per container in the region, 1,000 adult mosquitoes are being added to our environment on a daily basis, 30,000 monthly, and 360,000 yearly in only one region of the city.
Therefore, tyre puncture shops are playing a significant role in the continuous increase in mosquitoes in the country.
Extract from the research paper ‘Why the population of dengue vector mosquitoes is increasing in Karachi and other areas of Sindh’ by Rajput Muhammed Tariq and SM Naushad Zafar
Eradicating dengue vector mosquitoes is difficult due to the following reasons:

(i) Dengue vector mosquitoes are day-biter diurnal, i.e. they feed at daytime
(ii) People do not tend to use repellents at daytime.
(iii) People use mats, coils, smoke, sprays, mosquito nets and repellents only at night time, whereas they bite at daytime.
(iv) All precautionary measures – sprays, fogging and air sprays – are taken at homes, offices and closed buildings and on streets and roads, but the breeding places of the dengue vector mosquitoes, especially the tyre puncture shops are ignored.
(v) Dengue vector mosquitoes breed in clear drinking water, present in plastic containers, drums, tanks (both overhead and underground), earthen pots and pitches, cemented open tanks in graveyards, cattle sheds, plant nurseries and so at many unexpected places, they remain unaffected.
(vi) They can breed in a small quantity of water, even a glass of water; even on the upper part and the round lining of a drums having only ½ inch deep water.
(vii) They bite not only humans but small mammals as well.
Solutions for eradicating dengue vector
mosquitoes:
(i) Millions of rupees are spent on purchasing ambulances, platelet bags and isolating machines that remain non-functional as there are no trained operators. Many doctors are on emergency duty during the infection season but no funds are given to the technical people concerned, researchers, entomologists and biologists to control the breeding of the vector mosquitoes. Therefore this strategy must be changed.
(ii) Funds for projects for dengue vector mosquitoes control should be provided to the technical people concerned.
(iii) Continuous attention and research is needed and not seasonal.
(iv) Attention should be given on the vector control.
(v) The problem must be solved by indigenous resources, national experts, local researchers and scientists according to the local environment and needs.
(vi) The media can contribute to solving this problem by creating awareness about the mosquitoes, the disease, symptoms, precautions, solutions and controls.
(vii) Puncture tyre shops must be monitored throughout the year.
(viii) Dengue fever patients must be isolated from others because the mosquitoes carry the virus from the infected patients, and spread it among healthy people.
(ix) Repellents should be used at daytime as well.
(x) People should cover the body. Shorts and T-shirts as well as dark-coloured clothing, particularly black and red, should be avoided, because the mosquitoes are attracted to them.