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Vector borne diseases

  • Category
    Science & Technology
  • Published
    19th Sep, 2019
  • Vectors are living organisms that can transmit infectious diseases between humans or from animals to humans.
  • Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later inject it into a new host during their subsequent blood meal.

Issue

Context

Meaning of vectors:

  • Vectors are living organisms that can transmit infectious diseases between humans or from animals to humans.
  • Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later inject it into a new host during their subsequent blood meal.
  • Mosquitoes are the best known disease vector. Others include ticks, flies, sandflies, fleas, triatomine bugs and some freshwater aquatic snails.

Facts:

  • Vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700 000 deaths annually.
  • Dengue fever, together with associated dengue haemorrhagic fever (DHF), is the world's fastest growing vector borne disease.
  • Malaria causes more than 400,000 deaths every year globally, most of them are children under 5 years of age.
  • Other diseases such as Chagas disease, leishmaniasis and schistosomiasis affect hundreds of millions of people worldwide.

Meaning of Vector-borne diseases:

  • Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors.
  • The major vector-borne diseases, together, account for around 17% of all infectious diseases. The burden of these diseases is highest in tropical and subtropical areas and they disproportionately affect the poorest populations.
  • Since 2014, major outbreaks of dengue, malaria, chikungunya, yellow fever and Zika have afflicted populations, claimed lives and overwhelmed health systems in many countries.

Factors responsible for the distribution of vector-bornediseases:

  • These factors are determined by complex demographic, environmental and social factors.
  • Global travel and trade,unplanned urbanization and environmental challenges such as climate change can impact on pathogen transmission, making transmission season longer or more intense or causing diseases to emerge in countries where they were previously unknown.
  • Changes in agricultural practices due to variation in temperature and rainfall can affect the transmission of vector-borne diseases.
  • The growth of urban slums, lacking reliable piped water or adequate solid waste management, can render large populations in towns and cities at risk of viral diseases spread by mosquitoes.
  • Together, such factors influence the reach of vector populations and the transmission patterns of disease-causing pathogens.

Main vectors and diseases they transmit:

Vector

Disease

Aedes mosquito

  • Chikungunya
  • Dengue fever
  • Lymphatic filariasis
  • Rift Valley fever
  • Yellow fever
  • Zika

Anopheles mosquito

  • Malaria
  • Lymphatic filariasis

Culex mosquito

 

  • Japanese encephalitis
  • Lymphatic filariasis
  • West Nile fever

Sandflies

  • Leishmaniasis( Kala-Azar)
  • Sandfly fever (phelebotomus fever)

Ticks

 

  • Crimean-Congo haemorrhagic fever
  • Lyme disease
  • Relapsing fever (borreliosis)
  • Tick-borne encephalitis
  • Tularaemia

 

Triatomine bugs

 

  • Chagas disease (American trypanosomiasis)

Tsetse flies

  • Sleeping sickness (African trypanosomiasis)

Fleas

 

  • Plague (transmitted by fleas from rats to humans)
  • Rickettsiosis

Black flies

 

  • Onchocerciasis (river blindness)

Lice

 

  • Typhus and louse-borne relapsing fever

 

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