Transcript vector - Department of Pathological Physiology

Vector-Borne Diseases
-an overviewNur Nabilah Binti Ahmad Puzi
Nur Farah Deelah Binti Abdullah
What Is It?
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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.
Symptoms
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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
Dengue
Malaria
Typhus - rash
Epidemiology of vector-borne disease
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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.
Statistical data in Malaysia
Disease
Incident Rate
/100,000
Mortality rate
/100,000
Dengue
167.76
0.02
Malaria
2.67
0.01
Typhus
0.05
0
Plague
0
0
Yellow Fever
0
0
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.
Prevention of Vector-borne
diseases
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New strategies for prevention and control of vectorborne 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
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chemical methods of vector control
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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.
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
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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-bornediseases
http://en.wikipedia.org/wiki/Vector_%28epidemiolog
y%29
http://maps.grida.no/go/graphic/climate-changeand-vector-borne-diseases
http://www.who.int/heli/risks/vectors/en/vbdmap.pdf
http://health.state.ga.us/epi/vbd/index.asp
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http://www.nlm.nih.gov/medlineplus/ency/article/001363.htm
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