Vector-Borne Diseases -an overview-

1. Vector-Borne Diseases-an overview- Nur Nabilah Binti Ahmad Puzi Nur Farah Deelah Binti Abdullah

2. 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.

3. 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

6. Dengue

7. Malaria

8. Typhus - rash

9. 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.

10. 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.

11. Statistical data in Malaysia Ministry of Health Malaysia, 2008

13. 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.

15. 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.

16. 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.

17. 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

18. http://www.answers.com/topic/vector-borne-diseases • http://en.wikipedia.org/wiki/Vector_%28epidemiology%29 • http://maps.grida.no/go/graphic/climate-change-and-vector-borne-diseases • http://www.who.int/heli/risks/vectors/en/vbdmap.pdf • http://health.state.ga.us/epi/vbd/index.asp • http://www.nlm.nih.gov/medlineplus/ency/article/001363.htm