Combating vector borne diseases

Vectors are organisms that transmit pathogens and parasites from one infected person (or animal) to another. Vector borne diseases are illnesses caused by these pathogens and parasites in human population and account for 17% of the estimated global burden of all infectious diseases. Although, the disease most commonly found in tropical areas where 40% of the population is at risk, globalization, climate change and urbanisation have affected transmission of vector borne diseases and causing their appearance in countries where they were previously unknown.
Major Vector Borne Diseases

Sl.No.
Name of the Disease
Vector
Causative agent
Certitude
1.
Dengue
Infected Female
Aedes aegypti Mosquito
Virus
More than 2.5 billion people-over 40% of words population-are now at risk of dengue.
2.
Malaria
Infected female
Anopheles Mosquito
Parasite Plasmodium
Around the word, Malaria transmission occurs in 97 countries, putting about 3.4 billion people at risk
3.
Lymphatic filariasis or Elephantiasis
Infected Mosquitos
Culex, Anopheles, Aedes
Filarial parasite
More than 120 million currently infected and 40 million disfigured and incapacitated
4.
Chikungunya
Infected female
Aedes aegypti Mosquito
Virus
There is no specific treatment for the disease. Treatment is symptomatic.
5.
Yellow Fever
Infected Mosquito
Aedes and Haemagogus
Virus
Vaccination is the most important preventive measure against yellow fever. There is no specific treatment
6.
Schistosomiasis
Infested water. Larva of the Parasite released by fresh water snails.
Parasite Trematode flat worms(Blood flukes)
Disease prevalent in poor communities without safe drinking water and sanitation.
7.
Chagas disease (American Trypano somiasis)
Triatomine Bugs
(Kissing bugs)
Protozoan Parasite  Trypanosoma Cruzi
Potentially Life threatening condition. 7-8 million people infected worldwide, mostly in Latin America. There is no vaccine
8.
Congo-Crimean haemonhage fever
Tics and livestock animals
Nairo Virus
Case fatality rate up to 40%. There is no vaccine available for either people or animals.
9.
Human African trypanosomiasis (Sleeping sickness)
Infected Tsetse fly
Protozoan
Parasitc
Fatal without prompt diagnosis and treatment
10.
Leishmaniasis
(Kala-azar)
Infected Female sand flies
Protozoan Leishmania Parasites
Every year there are 1.3 million new cases and 20,000 to 30,000 deaths
11.
Lyme
Infected deer ticks
Borrelia Bacteria
It is now the most common tick borne disease in northern hemisphere
12.
Onchocerciasis
(River Blind Blindness)
Infected black flies
(Simulium spp.)
Parasitic worm onchocerca volvulus
In 2013 Colombia become the 1st country to be declared onchocerciasis free by WHO
13.
Japanese Encephalitis
Culex mosquito
Virus
Vaccine is the most preventive measure.  There is no specific treatment.


Prevention and control
Time has come to utilize the full potential for vector control for reducing vector-borne disease. Back in 1940's, the discovery of synthetic insecticides was a major breakthrough and the massive use of insecticides in 1940's and 1950's successfully brought many important vector-borne diseases under control. But, with in the past two decades, many important vector-borne diseases have re-emerged or spread to new parts of the world. Alongside this alarming spread of vectors there is a serious concern of increasing insecticide resistance. At the same time, the world is facing an extreme shortage of entomologists and vector control experts who promote 'integrated vector management' as the best approach to strengthen vector control. This approach uses a range of interventions, from indoor residual spraying to the use of natural insect predators, in combination and in a value added way. Integrated management makes sense as many vector borne diseases overlap geographically.

Key elements in the prevention and control of vector borne diseases include the following:
  • Long-lasting insecticidal nets.
  • Indoor residual spraying
  • Outdoor spraying
  • Addition of chemicals to water
  • Insect repellents like coils, vaporizing mats.
  • Reducing breeding habit of the vector 
  • Biological control of vectors through the introduction of parasites, predators or other living organisms.
  • Genetic control strategies.
  • Waste management.
  • Housing modification
  • Personal protection against the vector
  • Medication for travelers
  • Prophylaxis and preventive therapies.
  • Mass treatment for lymphatic filariasis, sotistosomiasis, onchocerciasrs.
  • Vaccines for Japanese encephalitis, Tick-borne encephalitis, and yellow fever.
  • Blood and body fluid safety in the case of Chagas disease and crimean-congo haemonhage fever.
  • Food safety in case of Chagas disease and Tick borne encephalitis.

Key challenges in the control of vector-borne diseases include
Ø  Emerging insecticide resistance.
Ø  Lack of expertise in vector control.
Ø  Surveillance of vectors and their diseases.
Ø  Sanitation and access to safe drinking water.
Ø  Pesticide safety and poisoning
Ø  Climate and environmental change.

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