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Vector-Borne Diseases

Vector-Borne Diseases. The Critical Role of Environmental Health in Vector Control and Disease Prevention. CAPT Michael E. Herring, REHS, MPH Senior Environmental Health Scientist CDC National Center for Environmental Health Environmental Health Services Branch.

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Vector-Borne Diseases

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  1. Vector-Borne Diseases The Critical Role of Environmental Health in Vector Control and Disease Prevention CAPT Michael E. Herring, REHS, MPH Senior Environmental Health Scientist CDC National Center for Environmental Health Environmental Health Services Branch National Center for Environmental Health Division of Emergency and Environmental Health Services

  2. Brain Teaser – What percentage of all diseases known to affect human-kind throughout history are zoonotic (of animal origin) and often transmitted by a vector? 60 Percent!

  3. Brain Teaser – 2What percentage of all new or emerging diseases that threaten human health today are zoonotic or vector-borne illnesses? 75 Percent!

  4. What animals are responsible for more human illness and death than any other group of mammals? Rats and Mice

  5. How many human diseases can be transmitted by rodents? 61

  6. Based on CDC projections, how many West Nile virus infections have occurred in the U.S. since the virus was first identified here in 1999? 1.8 Million!!!

  7. What disease vector ranks #1 in pathogen diversity? Ticks

  8. What type of tick is the likely the most common in the world? The Brown Dog Tick Rhipicephalussanguineus

  9. VectorTransmitters of disease-causing organisms that carry a pathogen from one host to another

  10. Vector-Borne Disease Transmission Biological • Most significant mode of transmission - Arthropod ingests a pathogen while taking a blood meal from an infected host - Pathogen multiplies within the arthropod (reservoir) - Pathogen is transmitted to another host when arthropod takes another blood meal Mechanical • Vector physically carries pathogens from one place or host to another, usually on body parts or through the gastrointestinal tract

  11. Vector-Borne Disease Transmission • Transovarian transmission - Infectious agent is passed vertically to succeeding generations • Transstadial transmission – infectious agent is passed from one stage of life cycle to another, as nymph to adult

  12. Emergence/Resurgence of Vector-Borne Diseases • Pesticide resistance • Decreased resources for surveillance, prevention and control • Deterioration of public health infrastructure • Unprecedented population growth • Uncontrolled urbanization • Changes in agricultural practices • Deforestation • Increased travel *Encyclopedia of Public Health

  13. What’s going on out there?

  14. Mosquito-Borne Disease

  15. West Nile Virus Total Cases in U.S. 1999-2009 Number of Cases (log scale) Year Reported Human Cases Reported Average = 2891/yr; range = 21-9862

  16. 12,188 WNND Cases X 28 WNF/WNND ~341,000 WNF Cases Reported WNND Cases, United States, 1999-2009* 12,188 WNND Cases x 140 infections/WNND ~ 1.7 Million Infections * Reported as of 2/4/2010

  17. WNV: The “Iceberg” WNND <1% WN Fever ~17% Asymptomatic ~82% 1 WNND : 28 WNF 1 WNND : 140 Total Infections

  18. Arboviral Nuroinvasive DiseaseAnnual average Cases 1999-2009 in the USA 119 Cases per year combined

  19. WNV: Long-Term Outcomes • WN Encephalitis and WN Fever • Persistent disabling neurologic sequelae common • Tremors, movement disorders, cognitive problems in >50% • 8 published studies show complaints frequently persist >1 year post infection (Some > 3 years) • Fatigue, pain, subjective memory / concentration problems • Higher all-cause mortality rates >1 year post-infection *# Sejvar et al., J Neuropsychol 2008; ^Greenberg et al., EID 2005;

  20. >300 Bird Species Killed by WNV Since 1999

  21. Mammals killed by WNV in the USA • Horse • Squirrel • Dog • Cat • Sheep • Domestic rabbit • Eastern Chipmunk • Striped Skunk • Bat • Raccoon

  22. Dengue • Dengue is transmitted between people by Aedesaegypti and Aedesalbopictus • More than one-third of the world’s population living in areas at risk for transmission • Over 100 million people are infected yearly • No vaccine and no specific treatment.

  23. Dengue • Dengue fever - high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain (“break-bone fever), rash, and mild bleeding • Dengue hemorrhagic fever – 2 to 7 days of high fever followed by persistent vomiting, severe abdominal pain and difficulty breathing. Next phase is a 24- to 48-hour period when capillaries become “leaky” leading to pleural effusions. May lead to circulatory system failure and shock, followed by death, if not treated.

  24. Tick-Borne Disease

  25. Lyme Disease • Caused by the bacterium Borreliaburgdorferi • Transmited to humans through the bite of • infected blacklegged ticks • The deer tick, (Ixodesscapularis) spreads the disease in the northeastern, mid-Atlantic, and north-central United States, and the western blacklegged tick (Ixodespacificus) spreads the disease on the Pacific Coast. • Symptoms - fever, headache, fatigue, and a characteristic skin rash called erythemamigrans (70 - 80% of infections) • If left untreated, infection can spread to joints, the heart, and the nervous system • #1 reportable vector-borne disease in the U.S. and the #5 most reported disease overall.

  26. Reported Cases of Lyme Disease by Year, United States, 1995-2009

  27. Reported Cases of Lyme DiseaseUnited States, 2009

  28. Range of Ixodespacificus(Western black-legged tick)

  29. Rocky MountainSpotted Fever • Caused by the bacterium Rickettsiarickettsii • Transmitted in the U.S. by the American dog tick (Dermacentorvariabilis, Rocky Mountain wood tick (Dermacentorandersoni), Lone Star tick (Amblyommaamericanum) and brown dog tick (Rhipicephalussanguineus) • Symptoms - fever, headache, abdominal pain, vomiting, and muscle pain. A rash may develop, but is often absent in the first few days, and in some patients, never develops • RMSF is a serious illness that can be fatal in the first eight days of symptoms if not treated correctly (doxycycline within 5 days)

  30. Tularemia • Caused by the bacterium Francisellatularensis. • Transmitted to humans by the dog tick (Dermacentorvariabilis), the wood tick (Dermacentorandersoni), and the lone star tick (Amblyommaamericanum). • Deer flies (Chrysops spp.) have been shown to transmit tularemia in the western U.S. • Highly infectious. A small number (10-50 or so organisms) can cause disease. • Potential bio-terror weapon. Commonly occurs in nature. People who inhale an infectious aerosol would experience severe respiratory illness, including life-threatening pneumonia and systemic infection.

  31. Tularemia • Ulceroglandular - Occurs following a tick or deer fly bite or after handing of an infected animal. Skin ulcer appears where the organism entered the body (most common form). • Glandular - Similar to ulceroglandular but without an ulcer. • Oculoglandular - Bacteria enter through the eye. Can occur when touching the eyes while butchering an infected animal. • Oropharyngeal - From eating or drinking contaminated food or water (sore throat, mouth ulcers, tonsillitis, and swelling of lymph glands in the neck.) • Pneumonic - Most serious form. Symptoms include cough, chest pain, and difficulty breathing. Results from breathing dusts or aerosols containing the organism.

  32. Reported cases of Tularemia, United States 2001-2010

  33. Flea-Borne Disease

  34. Plague • Caused by the bacterium Yersiniapestis. • Usually transmitted by the bite of an infected rodent flea or by handling an infected animal • The last U.S. urban plague epidemic occurred in Los Angeles in 1924-25 • Most human cases in the United States occur in two regions: 1) northern New Mexico, northern Arizona, and southern Colorado; and 2) California, southern Oregon, and far western Nevada

  35. Plague • Bubonic plague: enlarged, tender lymph nodes, fever, chills and prostration (total exhaustion/collapse) • Septicemic plague: fever, chills, prostration, abdominal pain, shock and bleeding into skin and other organs • Pneumonic plague: fever, chills, cough and difficulty breathing; rapid shock and death if not treated early

  36. RATS!!!

  37. Rats in the human environment cause enormous economic loss - Consume and contaminate vast quantities of food - Cause fires by gnawing the insulation from electric wires Commensal rodents cost billions of dollars each year in the United States. - Internal destruction to computers and other sensitive equipment - Structural damage to homes and businesses ECONOMIC IMPORTANCE

  38. Human Health Impact

  39. Rats and mice spread diseases in two distinct ways. Directly - by contamination of food, water and air with their urine and feces Indirectly – by way of rodent fleas, ticks and mites DirectIndirect Rat bite fever Plague SalmonellosisMurine typhus Leptospirosis Scrub typhus Hantavirus Tularemia RODENT-BORNE DISEASES

  40. Resurgence of a pest health departments have not dealt with in over 50 years. Bed Bugs

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