Vector-Borne Diseases -an overview-

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Vector-Borne Diseases-an overview-

• Nur Nabilah Binti Ahmad Puzi
• Nur Farah Deelah Binti Abdullah

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What Is It?

• vector - insect / any living carrier - transmits
  an infectious agent.
• vehicles by which infections are transmitted from
  one host to another - arthropods, domestic
  animals, or mammals
• vector -required for part of the parasite's
  developmental cycle- also transmits the parasite
  directly to subsequent hosts.
• Insects form a major group of disease vectors -
  mosquitoes, flies, ticks, lice and fleas.
• Many are haematophagous feed on blood at some
  or all stages of their lives.
• blood feed - parasite enters the blood stream of
  the host. Eg- The Anopheles mosquito, a vector
  for Malaria inserts its delicate mouthpart under
  the skin and feeds on its hosts blood.
• The parasites are usually located in its salivary
  glands (used by mosquitoes to anaesthetise the
  host). Therefore, the parasites are transmitted
  directly into the hosts blood stream.

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Symptoms

• Dengue Dengue is the most important viral
  disease transmitted by mosquitoes afflicting
  humans in a world context. Clinical symptoms
  range from mild fevers, violent headache, severe
  pains in the muscles and joints, to a potentially
  life threatening haemorrhagic disease.
• Malaria this disease results from infection with
  a protozoan blood parasite transmitted by various
  species of mosquitoes belonging to the genus
  Anopheles. The disease causes fever (usually
  periodic), varying degrees of anaemia and splenic
  enlargement, and a range of syndromes resulting
  from the physiological and pathological
  involvement of certain organs, including the
  brain, liver and the kidneys. The infection often
  can be fatal in the absence of treatment
• Typhus is a bacterial disease spread by lice or
  fleas. Symptoms include Abdominal pain back ache,
  dull red rash that begins on the middle of the
  body and spreads, extremely high fever (105 - 106
  degrees Fahrenheit), which may last up to 2
  weeks, hacking, dry cough, headache, joint pain
  (arthralgia), nausea, vomiting

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Dengue
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Malaria
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Typhus - rash
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Epidemiology of vector-borne disease

• Prevalent in the tropics and subtropics -
  relatively rare in temperate zones
• But, climate change could create conditions
  suitable for outbreaks of diseases such as Lyme
  disease, Rocky Mountain spotted fever, malaria,
  dengue fever, and viral encephalitis in temperate
  regions.
• There are different patterns of vector-borne
  disease occurrence.
• Parasitic and bacterial diseases such as malaria
  and Lyme disease, tend to produce a high disease
  incidence but do not cause major epidemics. An
  exception to this rule is plague, a bacterial
  disease that does cause outbreaks.
• In contrast, many vector viral diseases, such as
  Yellow fever, dengue, and Japanese encephalitis,
  commonly cause major epidemics.

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• There has been a worldwide resurgence of
  vector-borne diseases since the 1970s
• Reasons for the emergence or resurgence of
  vector-borne diseases -
• development of insecticide and drug resistance
• decreased resources for surveillance, prevention
  and control of vectorborne diseases
• deterioration of the public health infrastructure
  required to deal with these diseases
• unprecedented population growth
• uncontrolled urbanization
• changes in agricultural practices
• deforestation and
• increased travel.
• Changes have been documented in the distribution
  of important arthropod disease vectors.
• The yellow fever mosquito, Aedes aegypti has
  reestablished in parts of the Americas where it
  had been presumed to have been eradicated
• the Asian tiger mosquito, Aedes albopictus, was
  introduced into the Americas in the 1980s and has
  spread to Central and South America and
• the blacklegged tick, Ixodes scapularis, an
  important transmitter of Lyme disease and other
  pathogens, has gradually expanded its range in
  parts of eastern and central North America.

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Statistical data in Malaysia
Ministry of Health Malaysia, 2008
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• The highest mortality rate is in Africa region
  since in the world statistic it shows that the
  highest Malaria disease is at Africa.
• Malaysia has relatively high mortality rate due
  to the tropic region in which it is suitable for
  the vector to breed.

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• climate change and altered weather patters would
  affect the range (both altitude and latitude),
  intensity, and seasonality of many major tropical
  vector-borne and other infectious diseases - such
  as malaria and dengue fever.

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Prevention of Vector-borne diseases

• New strategies for prevention and control of
  vector-borne diseases are emphasizing "Integrated
  Vector Management" as an approach that
  reinforces linkages between health and
  environment, optimizing benefits to both.
• The most deadly vector borne disease, Malaria,
  kills over 1.2 million people annually.Dengue
  fever, together with associated dengue
  haemorrhagic fever (DHF), is the world's fastest
  growing vector borne disease.
• Poorly designed irrigation and water systems,
  inadequate housing, poor waste disposal and water
  storage, deforestation and loss of biodiversity,
  all may be contributing factors to the most
  common vector-borne diseases including malaria,
  dengue and leishmaniasis.

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• environmental management
• strategies that can reduce or eliminate vector
  breeding grounds altogether through improved
  design or operation of water resources
  development projects as well as use of biological
  controls (e.g. bacterial larvicides and
  larvivorous fish) that target and kill vector
  larvae without generating the ecological impacts
  of chemical use.
• chemical methods of vector control
• such as indoor residual sprays, space spraying,
  and use of chemical larvicides and adulticides
  these reduce disease transmission by shortening
  or interrupting the lifespan of vectors.
• Personal protection/preventive strategies
• that combine environmental management and
  chemical tools for new synergies e.g.
  insecticide-treated nets

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• http//www.answers.com/topic/vector-borne-diseases
  
• http//en.wikipedia.org/wiki/Vector_28epidemiolog
  y29
• http//maps.grida.no/go/graphic/climate-change-and
  -vector-borne-diseases
• http//www.who.int/heli/risks/vectors/en/vbdmap.pd
  f
• http//health.state.ga.us/epi/vbd/index.asp
• http//www.nlm.nih.gov/medlineplus/ency/article/00
  1363.htm