Dengue : Coastal States hit

Aedes Aegypti mosquito

The Aedes Aegypti mosquito is the notorious transmitter of the deadly dengue, chikungunya, zika and yellow fever virus. It can be recognized by the white markings on its legs and thorax. After originating in Africa it have worked it way all over the world in tropical and sub-tropical regions.

440px-Aedes_aegypti_larva

440px-Aedes_aegypti

Source: Wikipedia

 

 

 

 

 

  • Only the females bite for blood (to mature their eggs)
  • Although the feed mostly between dawn and dusk, they can bite during any time and spread infection all year long
  • Prefer wet shower tanks and toilet tanks. The chemicals released by the water borne bacteria stimulate the mosquitoes to lay their eggs
  • Although the lifespan of a mosquito is 2-4 weeks, the eggs can be viable in a dry state for over a year surviving the winter
  • Given the high population densities in tropical and subtropical regions, Basic Reproduction Rate Z0 (#Persons to whom the disease spreads from a infected person, Z0<1 means the disease with eventually get eradicated without active means) for  Dengue and other diseases spread by Aedes is in the range of 3-8.
Dengue in India : 2016

 

We looked at the absolute cases [top] of Dengue [as reported http://nvbdcp.gov.in/den-cd.html] and cases as a percentage of the State population [bottom].

  • The incidences looks extremely high in whole West Coast from Kerala to Gujarat. On the East Coast both West Bengal and Orissa seem to be badly affected.
  • However on normalizing the dengue cases by the state population EXTREMELY high numbers were found in the tiny West Coast Union Territory of Dadar and Nagar Haveli [3hr from Mumbai]. The number is as high as ~100 cases for every 1 Lakh persons.
  • Kerala and Orissa also have high incidence of dengue [15, 16 persons per 1 Lakh persons]
  • 3.5 deaths for every 1000 infected [Research Paper]

READ MORE: Chikungunya Fever : Karnataka worst affected State | Statewise Policies, not Rainfall Drive Farmer Suicides in India

Slow and steady increase in Dengue cases

* 2016 number an estimate based on numbers reported till Sept 18, 2016

READ MORE: Chikungunya Fever : Karnataka worst affected State | Small World connectivity in rural road networks

How other countries fought against the Dengue

Indonesia

  • Community awareness : Within each neighbourhood houses are grouped in sets of 10. Each group assigns a leader who is trained in dengue prevention and control. Group leader also has a source reduction kit – to inspect their areas weekly for larval growth. Data is collected every week from each of these neighbourhoods to evolve the program.
  • Eliminate Dengue Indonesia released Wolbachia mosquitoes in communities around Yogyakarta, a densely populated city with a high prevalence of dengue outbreaks. The aim of these releases is to establish Wolbachia in the local mosquito populations to reduce the transmission of dengue between people.

Malaysia

  • In Johor state, an integrated social mobilisation motivated householdersto destroy any larval breeding sites found around their premises, and to organise voluntary teams to inspect and control larval breeding sites in public spaces such as community halls, parks and vacant lots. Dengue Volunteer Inspection Teams (DeVIT) were formed in 48 localities. During the three-month campaign period, the teams advised 1,00,956 people, distributed 1,01,534 flyers, and inspected 1,440 vacant lots. The campaign resulted in a dramatic drop in the occurrence of dengue in the district. Three months after the campaign, tracking surveys revealed that 70 per cent householders were still checking their premises.

Singapore

  • Authorities have urged residents to adopt the “mozzie wipeout” routine, which includes changing water in vases and bowls on alternate days and adding insecticide to roof gutters monthly.

Colombia

  • In Bucaramanga, high school students were trained in “Aedes aegypti biology and control” and assisted as community-based health educators. Results over 11 years (1992-2001) showed a steady decrease in the number of houses with larvae present.

China, Australia 

Similar to the efforts in Indonesia the aim is to to mate genetically modified Wolbachia mosquitoes with the Dengue causing ones to remove the disease from its root itself. As reported by the Chinese, Australian (Queensland) experience, there was 90% reduction in the Dengue cases.

Brazil

The plan involves genetically engineering the male of the Aedes Aegypti species which carries the dengue virus but loading a “self-limiting” gene which means their offspring would die before reaching adulthood, thus controlling the population. Initial trials in the Cayman Islands showed a reduction in the female population of 90%. [http://www.oxitec.com/]

TED talk on Re-engineering mosquitoes 

READ MORE: Chikungunya Fever : Karnataka worst affected State | Statewise Policies, not Rainfall Drive Farmer Suicides in India

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