Lowering The Risk of Mosquito-Borne Diseases. How do you avoid a mosquito-borne disease?

Transcription

1 Presentation to: Presented by: Date: Lowering The Risk of Mosquito-Borne Diseases Tiffany Nguyen, PhD MPH How do you avoid a mosquito-borne disease? Don t get bit by a mosquito! If only it were that easy. 1

2 A Little Bit About Mosquitoes Order Diptera: True Flies Family Culicidae: Mosquitoes ~3,500 species worldwide ~176 species are found in the US ~76 species are found in the Southeast US ~60 species of mosquitoes are found in Georgia Aquatic insects Three Groups Floodwater Containers Permanent water Importance Pests of humans Vectors of disease Not all mosquitoes are nuisance or vector species for humans. However, mosquitoes cause more human suffering than any other organism - over one million people worldwide die from mosquito-borne diseases every year. Some Background Mosquitoes have been a problem for people all over the world as long as humans have existed. This stems partly from the fact that the 3500 or so known species of mosquitoes have found places to live and roles to fill in almost every climate and ecosystem available. They have evolved many behaviors and modifications over thousands of years to make them very good at what they do. These include: Specialized mouthparts for blood feeding Incredible sensory perception 2

3 LIFE STAGES Mosquitoes undergo complete metamorphosis, so a mosquito's life can be divided into 4 major life stages. These are: The egg The larva (plural= larvae) The pupa (plural= pupae) The adult Each of these stages has a body that is specially designed for the type of activities it will be doing. Eggs Female mosquitoes lay their eggs either on water, on the sides of containers, or on soils that are periodically flooded After laying, eggs generally require 2-5 days of incubation before hatching Eggs laid in permanent water will hatch after incubation Eggs laid in tree holes, containers, or floodwater areas will hatch when covered with water after a period of incubation Most eggs are very resistant to environmental conditions Eggs may stay viable for many years 3

4 Laid singly On water Anopheles Coquillettidia On land Aedes & Ochlerotatus Psorophora Egg rafts Culex spp. Culiseta spp. Eggs Larvae Four instars It generally takes 3 to 7 days to complete development depending on food and temperature Most larvae are filter feeders Larvae breath air but can absorb oxygen through the body wall emerging larvae 4

5 Types of Larvae = wigglers Culicine: All genera other than Anopheles Culex, Ochlerotatus, Aedes, Psorophora, Culiseta Anopheline: All the Anopheles species Types of Larvae = wigglers Specialized Predatory Toxorhynchitis spp & some Psorophora spp Cryptic Coquillettidia spp & Mansonia spp 5

6 Pupae = tumblers Air breathers Do not feed Mobile Generally takes 1-2 days before the adult emerges Emergers 6

7 Adults Mosquitoes mate soon after emerging Male mosquitoes emerge first and wait for the females to emerge Male mosquitoes die soon after mating A female will lay approximately eggs per one oviposition cycle An oviposition cycle starts after the blood meal and ends when eggs are laid A female can go through about 10 oviposition cycles Most female mosquitoes live at least 2 weeks, and may live 2 months or more WHAT DO MOSQUITOES EAT? Plant juices & nectar Females of most species also need blood from other animals 7

8 WHY DO FEMALE MOSQUITOES NEED YOUR BLOOD? They use the blood to help develop eggs Females generally begin blood feeding following mating Eggs are ready to be laid approximately 3 days following a blood meal There are two general categories within which mosquito breeding habitats exist: Natural mosquito breeding habitats Man-made mosquito breeding habitats These breeding areas can be found in habitats that exist naturally, such as within a pond or flood plain, or in habitats that have been created by humans, such as bird baths, water-filled tires, or catch basins. 8

9 Mosquito Breeding Habitats Female mosquitoes lay their eggs either on water, on the sides of containers, or on soils that are periodically flooded. NATURAL MOSQUITO BREEDING HABITATS Temporary Woodland Pools (floodwater) Freshwater Ponds (permanent) Streams (varies) Floodplains (floodwater) Tree Holes and Other Natural Containers (containers) Freshwater Marshes and Swamps (varies) MAN-MADE MOSQUITO BREEDING HABITATS Stormwater/Wastewater Detention (containers) Roadside Ditches (varies) Artificial Containers (containers) Swimming pools (varies) Ruts (floodwater) Habitats Fresh, Brackish, or Saltwater Permanent water eggs (e.g. Culex, Anopheles) are laid directly on water - ponds, pools, and streams and hatch after incubation. Floodwater eggs (e.g. Psorophora, Aedes, Ochlerotatus) are laid on moist soil - ditches, floodplains, depressions and upper marsh and hatch after inundation and incubation. Eggs laid above water-line: Natural containers like rock holes, water holding plants, and tree holes. Artificial containers like buckets, birdbaths, flower pots, rain gutters, tires, cans, and boats. 9

10 Flood-water Mosquito Habitats Permanent-water Mosquito Habitats 10

11 Container Habitats Mosquitoes and Swimming Pools Mosquitoes only need one inch of standing water to breed and can complete their life cycle in as little as one week, turning into biting adults. Breeding sites for mosquitoes that are close to residential areas are a danger to public health and safety. Green Pools are a perfect place for mosquitoes to breed. Algae grows in pools when there is not enough chlorine or the filtration system has stopped working properly. Green pools are a threat to public health because mosquitoes can carry West Nile virus and other diseases that harm humans. 11

12 Tires are love at first sight for species such as Ochlerotatus japonicus, Aedes albopictus and Oc. triseriatus Pitcher Plants Wyeomyia smithii Every leaf has a deep cavity filled with digestive fluid Parker Whitt, NC PHPM,

13 Mosquitoes & Diseases In the late 1890s, scientists first discovered that mosquitoes transmit the parasites responsible for malaria. Since then, mosquitoes have been found to be vectors (an organism that transmits a disease) for a variety of disease organisms that afflict human populations all over the world. Mosquitoes can not only carry disease organisms that afflict humans, they also transmit viruses and parasites that affect animals. In the United States, the most common diseases carried by mosquitoes are: Eastern Equine Encephalitis St. Louis Encephalitis Some emerging or re-emerging diseases include: Chikungunya Dengue Zika virus LaCrosse Encephalitis West Nile Virus Dog Heartworm Disease Issues Most Common Arboviral Diseases in Georgia West Nile Virus* Lacrosse Encephalitis* Eastern Equine Encephalitis* Primary Vectors WNV Culex quinquefasciatus (Southern House Mosquito) LAC Ochlerotatus triseriatus (treehole mosquito) EEE Culiseta melanura (birds); many others (mammals) *zoonotic diseases 13

14 WNV in Companion Animals and Livestock, GA The map shows counties reporting WNV+ birds, horses and other livestock or companion animals, mosquitoes, and humans Counties with no reported positives have done little to no surveillance; WNV is considered endemic in Georgia Culex quinquefasciatus is the primary vector of WNV in Georgia HUMAN CASES WNV in Georgia # CASES # DEATHS # cases * # human positives all deaths 14

15 LAC 6is very under-reported in Georgia. LAC Cases in Georgia # cases Ochlerotatus triseriatus is the 4primary vector of LAC year EEE Human Cases, GeorgiaEEE is endemic in south Georgia. 3 Almost all the cases we see are in horses. 2 Culiseta melanura is the enzootic vector

16 90 Eastern Equine Encephalitis in Veterinary Cases, Georgia # Cases Year Mosquitoes & the EXOTIC Diseases they Transmit Mosquito Species Aedes aegypti Aedes albopictus Disease Organism Chikungunya Dengue Zika 16

17 Arboviral Encephalitis in the United States These are all zoonotic diseases. 33 Mosquitoes & the Parasites they Transmit Mosquito Species Anopheles spp Disease Organism malaria 17

18 Eradication of Malaria in the United States ( ) The National Malaria Eradication Program, a cooperative undertaking by state and local health agencies of 13 Southeastern states and the CDC, originally proposed by Louis Laval Williams, commenced operations on July 1, By the end of 1949, over 4,650,000 house spray applications had been made. In 1947, 15,000 malaria cases were reported. By 1950, only 2,000 cases were reported. By 1951, malaria was considered eradicated from the United States. Anopheles quadrimaculatus is historically the most important vector of malaria in the eastern United States. Malaria was a serious plague in the United States for centuries until its final eradication in the 1950s. Mosquitoes & the Parasites they Transmit Mosquito Species a variety of species Disease Organism dog heartworm 18

19 Heartworm 37 Heartworm Infection rates in Georgia: 80% in dogs over 2.5 years old 100% in dogs over 5 years old Wild canids are the enzootic host The primary vectors are Culex quinquefasciatus and Aedes albopictus Dogs MUST receive prophylaxis to prevent infection and death Cats can also be infected and can become very ill, even though most worms in cats do not survive to the adult stage; 61% 90% of unprotected cats exposed to infective larvae become infected In humans, worms are unable to mature, but will instead produce nodules under the skin or conjunctiva and lung granulomas 19

20 Mosquito Myths Can AIDS be transmitted by mosquitoes? There is no scientific evidence to suggest that this is possible. Is it impossible? It is safe to say that the involvement of blood-feeding insects and arthropods is biologically insignificant if it occurs at all. What can be done about mosquitoes? Vector control sources reduction, and application of larvicide and adulticide in affected areas. Personal protection minimize time spent outdoors when mosquitoes are most active wear long-sleeved shirts and pants applying mosquito repellents that contain EPA-registered active ingredients to exposed skin make sure screens are tight-fitting and in good repair Public education - protective measures (personal/home/yard) person-to-person media Enhanced awareness & communication between: mosquito control programs commercial pest control medical and veterinary practitioners public health 20

21 Integrated Mosquito Management Source Reduction Larval Surveillance - Larval Control Adult Surveillance - Adult Control Community Education / Communication Mapping / Record Keeping Mosquito-control operations are targeted against three different, but potentially interconnected, problems: Nuisance mosquitoes bother people around homes or in parks and recreational areas; Economically important mosquitoes reduce real estate values, adversely affect tourism and related business interests, or negatively impact livestock or poultry production; Public health is the focus when mosquitoes are vectors of infectious disease. 21

22 A Useful Approach Inspection: breeding sites, resting areas, potential concerns Identification: area needing treatment, mosquito species, and any current breeding sites Source reduction: eliminating breeding sites and the success rate of mosquito breeding on property Larvicide treatment: targets standing water or areas where mosquito larvae are found Adulticide treatment: BARRIER SPRAY: targets adult mosquito resting areas AREA SPRAY: targets mosquitoes as they fly in search of a blood meal or oviposition site 43 22

23 Source Reduction Dispose of tin cans, plastic containers, ceramic pots, & used tires Drill holes in the bottom of containers that are left outdoors (recycling bins) Clean clogged roof gutters Turn over plastic wading pools when not in use Change water in birdbaths every week Use landscaping to eliminate standing water that collects on property. Educating the Public Help yourself and your neighbors Tip and toss (source reduction) Neighborhood cleanup Wear repellent (bite prevention) 23

24 Bite Prevention Repellents: The same respect and caution should be used when using repellents as with other insecticides. Choose a repellent that best fits your outdoor activity. Apply repellents to areas that are exposed. Do not apply repellents to open wounds, eyes or mouth. Wash off repellents after going indoors. ALWAYS READ & FOLLOW THE LABEL Recommended repellents are those that contain DEET Picaridin IR3535 PMD (oil of lemon eucalyptus) Permanone ONLY on clothing

25 Bite Prevention Barriers Limit outdoor activities Keep windows and doorways tightly sealed Wear protective clothing Mosquito netting can also be used to protect one s face and neck or used on infant carriages, strollers and playpens The importance of mosquito surveillance Prevention & control of mosquito-borne diseases Identify local mosquito species ID & assess the extent of the mosquito problem Determining what control measures need to be used Source reduction Larviciding Adulticiding Monitoring changes in mosquito problems Detect emerging mosquito-borne diseases in the local area Evaluate the potential for transmission of mosquito-borne diseases Ecological and biological data Flight phenology Resting and Breeding sites Host feeding preference 50 25

26 CDC Light Traps CDC Traps can be used in a variety of ways to sample different species of adult mosquitoes. CDC has developed a portable trap that runs off a 6-volt battery or 4 D cell batteries. The commonly used CDC trap has a light source and a CO 2 source, located at the top of the trap to attract adult mosquitoes. As the mosquitoes approach the trap, a small fan draws them into a net, which is located at the bottom of the trap. Many mosquitoes are active during the evening and into the night so CDC traps are most often deployed at dusk and picked-up after dawn. 51 Gravid Traps Gravid Traps use a dark container and powered by a 6-volt battery. A fan housed above the water draws the gravid females into a box or net. These traps are very important to a mosquito control program s disease surveillance in that they collect gravid females (blood fed females ready to lay eggs). Highly organic water used as the attractant will predominately catch Culex species, which are important vectors of WNV

27 Mosquito Traps Carbon dioxide baited traps do attract and trap many adult mosquitoes Can be expensive Some technical problems Do not attract all species DO NOT USE NEAR HOUSE OR POOL people are more attractive than traps Things That Do Not Work Mosquito-repelling plants, such as the citrosa plants, do not significantly reduce mosquito numbers or mosquito bites Citronella candles don t work any better than regular candles, which don t do much to stop mosquitoes Electronic repellents High frequency sounds do not repel mosquitoes, or other pests Electronic bug zappers do not control mosquitoes or other flying pests Electronic fly swatters are an accident waiting to happen mosquito-repelling wrist bands 27

28 Top 12 Mosquito Species Collected ( ) Species 2015 Totals 13 Counties Percentages 2016 Totals 57 Counties Percentages 2017 Totals 159 Counties Percentages Ae. aegypti % % % Ae. albopictus % % % Ae. vexans % % % Oc. trivittatus 0 0% 0 0% % Oc. japonicus % % % Cq. perturbans % % % Cx. coronator % % % Cx. nigripalpus % % % Cx. quinquefasciatus % % % Cx. restuans % % % Cx. salinarius % % % Cs. melanura % % % 55 Cx. coronator

29 Aedes japonicus What is Pesticide Resistance? Repeated Pest species use are of the exposed to a large same class of variety of natural pesticides to control chemicals, and evolve a chemical pest can resistance cause via undesirable natural selection changes - in the most gene resistant pool of a pest organisms leading are to the a ones form to survive of artificial and pass on their genetic traits to selection, pesticide their offspring. resistance

30 Managing Resistance Pest resistance to a pesticide can be managed by reducing selection pressure by this pesticide on the pest population. This can be achieved by: avoiding unnecessary pesticide applications using non-chemical control techniques leaving untreated refuges where susceptible pests can survive Adopting the integrated pest management (IPM) approach usually helps with resistance management. 59 Integrated Mosquito Management Community Education / Communication Mapping / Record Keeping Source Reduction Larval Surveillance - Larval Control Adult Surveillance - Adult Control 60 30

31 The CDC did a transect a while back that showed knockdown resistance (kdr) genotype-phenotype, resulting in reduced neuronal sensitivity to pyrethroids, is present in the Culex pipiens complex in every east coast state from New York to Florida. Where kdr is fixed* at near 1.0, permethrin use, even synergized with PBO, will be problematic. *fixation is the change in a gene pool from a situation where there exists at least two variants of a particular gene (allele) to a situation where only one of the alleles remains 61 ANY QUESTIONS??? Thuy-vithi.nguyen@dph.ga.g