history and status of global vector borne disease by SANJU SAHpptx.pptx

Vector-borne diseases, transmitted by insects like mosquitoes and ticks, have impacted human health for centuries, causing illnesses such as malaria, dengue, and Lyme disease. Globalization, climate change, and urbanization have influenced their spread. Despite advances in control and treatment, these diseases remain significant public health challenges worldwide.

1. HISTORY AND STATUS OF GLOBAL VECTOR BORNE DISEASES Presented By: SANJU SAH St. Xavier’s College, Maitighar, Ktm MS.C. Microbiology Department

2. INTRODUCTION Vector-borne diseases are illness caused by pathogens and parasites which are transmitted by vectors in human populations. Example: Malaria, Dengue, Schistosomiasis, Human African trypanosomiasis, Leishmaniasis, Chagas disease, Yellow fever, Japanese encephalitis, Onchocerciasis etc. Etiological agent transmitted by vectors.

3. Vector are living organisms that transport and inoculate causative agent of infectious diseases between humans, from animal to human or from fomite to human. Some pathogens also undergo obligate stage of their life cycle inside vector. May be invertebrates (usually arthropods), fomites (inanimate objects contaminated with disease causing microorganisms) or vertebrates (rodents that carry agents from reservoir to susceptible host).

4. INTRODUCTION Many are bloodsucking insects ingesting disease-producing microorganisms during blood meal from infected host (human or animal) and later injecting it into new host during their subsequent blood meal. Most common vector-borne diseases carried through mosquitoes and ticks . Aedes mosquito Anopheles mosquito Culex mosquito

5. Phlebotomus sandfly Ticks carrying Lyme disease Triatomine bugs Tsetse flies Fleas for transmitting plague Black flies <- Aquatic snail

6. INTRODUCTION Vectors transmitting infectious disease Disease caused Mosquitoes : Aedes Anopheles Culex Dengue fever, Rift Valley fever, Yellow fever, Chikungunya Malaria Japanese encephalitis, Lymphatic filariasis, West Nile fever Sandflies Leishmaniasis, Sandfly fever ( Phelebotomus fever) Ticks Crimean-Congo haemorrhagic fever, Lyme disease, Relapsing fever (borreliosis), Rickettsial diseases (spotted fever and Q fever), 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) Aquatic snails Schistosomiasis (bilharziasis)

7. History of global vector-borne disease: Arthropods were shown to transmit human disease 120 years ago. Since then hundreds of viruses, bacteria, protozoa, and helminths have been found to require a hematophagous arthropod for transmission between vertebrate hosts. From 17 th to early 20 th century, malaria, dengue, yellow fever, plague, filariasis, louse-borne typhus, trypanosomiasis, leishmaniasis and other vector-borne diseases were responsible for more human disease and death than all other causes combined.

8. In 1877, filariasis was found to be transmitted by mosquitoes from human to human. Similar transmission cycles was found for malaria in 1898, yellow fever in 1900 and dengue in 1903. By 1910, other major vector-borne diseases (African sleeping sickness, plague, Rocky Mountain spotted fever, relapsing fever, Chagas disease, sandfly fever and louse-borne typhus) had shown to require blood-sucking arthropod vector for disease transmission to humans.

9. History of global vector-borne disease : During 19 th and 20 th centuries, vector-borne diseases were prevented from development in large areas of the tropics, especially in Africa. Prevention and control programs based on controlling arthropod vector (by eliminating arthropod breeding site and using chemical insecticide) followed. Yellow fever in Cuba- 1 st vector-borne disease to be effectively controlled in this manner, followed quickly by yellow fever and malaria in Panama.

10. Over next 50 years, most of the important vector-borne public health problems effectively controlled. By 1960s, vector-borne diseases were no longer considered major public health problems outside Africa. Urban yellow fever and dengue effectively controlled in Central and South America and eliminated from North America. Malaria nearly eradicated in America, The Pacific Island and Asia.

11. History of global vector-borne disease: Discovery and effective use of residual insecticides in 1940s, 1950s and 1960s contributed greatly to these successes. Benefits of vector-borne disease control programs were short-lived. Number of vector-borne diseases began to reemerge in the 1970s. Malaria and dengue found to reemerge in America and Asia.

12. Global vector-borne disease timeline: 323 BC: Alexander the Great died very likely of malaria. 71-79 AD: Roman army lost over 40,000 men (more than half soldiers) to malaria while invading Scotland. 11C and 12C: French- and German-born popes died of malaria. 1647-1650: Yellow fever brought from Africa to Barbados on slave ships; 6,000 wealthy white settlers on the island died during an outbreak lasting several years due to absence of immunity against disease.

13. 1742: More than half of 12,000 British army sent to Colombia died of mosquito-borne disease. 1793: In Philadelphia, USA, outbreak of yellow fever occurred during long hot summer when ships arrived from West Indies causing about 5,500 inhabitants to die before winter began when mosquitoes could no longer survive. 1800s: Local populations in Africa and Asia had immunity to yellow fever and malaria while European explorers and soldiers did not leading to death of thousands of them.

14. Global vector-borne disease timeline: 1802: Among 29,000 French soldiers and sailors sent to regain Haiti, only 6,000 returned defeated due to loss of soldiers caused by yellow fever to which Haitians had immunity. 1830s-1880s: Europeans began to associate good health with cleanliness; efforts to improve public sanitation began to reduce malaria and yellow fever. No one knows the connection between mosquitos and disease. 1881: Mosquito-borne disease caused death of thousands of workers during initial attempts to build Panama Canal.

15. 1897: Young British scientist Ronald Ross discovered that malaria parasite enters the human blood stream through a mosquito bite and mosquito is vector of disease. 1900: Following Ross’s discovery, entomologists worldwide began to plot military style attacks on mosquito.

16. Global vector-borne disease timeline: 1904: The USA, under President Theodore Roosevelt took over work on Panama Canal. William Crawford Gorgas eliminated yellow fever in Cuba then was hired to eliminate yellow fever and malaria from Panama Canal. 1930: In Brazil, entomologist Raymond C. Shannon found malaria vector -  Anopheles gambiae  which probably arrived from West Africa on destroyer ship used to deliver mail. 1943: Insecticide DDT (dichloro-diphenyl-tichloroethane) was invented; eradication of mosquitos became real possibility; battle against malaria was declared almost won. 1958: DDT was shipped to countries in Southern hemisphere struggling with mosquito-borne disease but mosquitoes developed resistance to DDT quickly.

17. History of global vector-borne disease: 1962: US scientist, Rachel Carson published  Silent Spring , book arguing that DDT is not safe; immediately DDT was banned in several US states. It was banned nation-wide ten years later. 1970s: Number of vector-borne diseases began to reemerge; malaria and dengue started to reemerge in America and Asia.

18. Present status of global vector-borne disease: Vector-borne diseases are currently prevalent in tropics and subtropics and relatively rare in temperate zones; mostly in developing countries. WHO estimated number of new cases of most serious vector borne disease per year include: Vector borne diseases New cases per year Malaria 270 million Schistosomiasis 200 million Lymphatic filariases over 90 million Onchocerciasis nearly 18 million Leishmaniasis 12 million Dracunculiasis 1 million African -trypanosomiasis 25,000

19. Present status of global vector-borne disease: Every year, more than 1 billion cases and over 1 million deaths occur from vector-borne diseases globally. Accounts for over 17% of all infectious diseases. Many of them preventable through informed protective measures. Since 2014, major outbreaks of dengue, malaria, chikungunya, yellow fever and Zika have affected populations, claimed lives and overwhelmed health systems in many countries.

20. Malaria - most deadly vector-borne disease in present condition; 40% of world population at risk. Cause more than 4,00,000 deaths every year globally, most of them occurring in children under 5 years of age. In 2012, caused an estimated 6,27,000 deaths. Dengue - world's fastest growing vector-borne disease, with 30-fold increase in disease incidence over last 50 years. More than 3.9 billion people in over 128 countries are at risk of contracting dengue, with 96 million cases estimated per year.

21. Present status of global vector-borne disease: Chagas disease, Leishmaniasis, Zika virus infection and Schistosomiasis are affecting hundreds and millions of people worldwide. Latest data revealed by municipal corporation in Delhi on vector-borne diseases stated 59 cases of malaria , 50 cases of dengue and 105 cases of chikungunya from January 1 to June 17. 105 cases of chikungunya was recorded in just 17 days in June. Malaria, Japanese encephalitis and Dengue observed in Nepal, usually in terai regions during monsoon.

22. Reasons behind increase in incidence of vector borne diseases: Global climatic change, particularly increase in earth’s temperature. -> 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 affects transmission of vector-borne diseases. Destruction of habitat, unplanned urbanization. -> Growth of urban slums, lacking reliable piped water or adequate solid waste management render large populations in towns and cities at risk of viral diseases spread by mosquitoes. Global travel and trade.

23. Prevention: Providing education and improving awareness so that people know how to protect themselves and their communities from mosquitoes, ticks, bugs, flies and other vectors. Getting vaccinated before travelling to countries with endemic vector borne diseases. For many diseases such as Chagas disease, malaria, schistosomiasis and leishmaniasis, WHO has initiated control programmes using donated or subsidized medicines.

24. More information about vector-borne diseases Chagas disease Life-threatening condition transmitted through triatomine bugs, contaminated food, infected blood transfusion Chikungunya Viral disease transmitted to humans by infected mosquitoes Congo-Crimean haemorrhagic fever Severe illness caused by a number of viruses Dengue Mosquito-borne infection that may cause lethal complications Dracunculiasis (guinea-worm disease) Infection caused by drinking-water containing water fleas that have ingested Dracunculus larvae Human African trypanosomiasis   Glossina -borne parasitic infection, fatal without prompt diagnosis and treatment

25. Leishmaniasis Infection is caused if bitten by female sandflies Lymphatic filariasis Infection occurs when filarial parasites are transmitted to humans through mosquitoes Lyme disease Disease caused by infected ticks Malaria Disease caused by a parasite  plasmodium , transmitted via infected mosquitoes Onchocerciasis Parasitic disease caused by the filarial worm  onchocerca volvulus Schistosomiasis Parasitic disease caused by trematode flatworms of the genus Yellow fever Viral disease transmitted via  aedes  mosquitoes

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