380 likes | 498 Views
Stephen L. Doggett Senior Hospital Scientist. Department of Medical Entomology Institute for Clinical Pathology & Medical Research, Pathology West, Westmead Hospital, Westmead NSW 2145. Ticks: overview Biology: lifecycle & ecology Tick Management Avoidance Repellents Efficacy
E N D
Stephen L. DoggettSenior Hospital Scientist Department of Medical Entomology Institute for Clinical Pathology & Medical Research, Pathology West, Westmead Hospital, Westmead NSW 2145
Ticks: overview Biology: lifecycle & ecology Tick Management Avoidance Repellents Efficacy Human safety Overview
Ticks • Worldwide – about 800 sp. • Australia – 75 (~15 attack humans) • 2 groups – Soft & Hard ticks • Most important - Ixodes holocyclus • Paralysis tick, scrub, bush, shell back • Seed, grass (larval stage)
AdultFemale AdultMale 1mm Nymph Larva
Tick Life Cycle Paralysis tick, Ixodes holocyclus
0.5m 3m Host Seeking Behaviour
When are ticks active? • Most of the year • Survival dependant on humidity • Most active: • Following rain • Periods of high humidity • Larvae far more common than other stages • High mortality in larval stage to nymph
Red-necked Wallaby Northern Brown Bandicoot Norwegian Rat House Mouse Southern Brown Bandicoot Bush Rat Magpie Long-nosed Bandicoot Grasslands Melomys Water Rat Australian Raven Mountain Brushtail Possum Common Brushtail Possum Crimson Rosella Domestic Fowl Brush-tailed Phascogale Pied Butcherbird Human Echidna Dog Koala Swamp Wallaby Common Dunnart Cat Feathertail Glider Pig Rabbit Black Rat Red-legged Pademelon Eastern Grey Kangaroo Animal Hosts After Roberts (1970)
Tick Removal MAKE SURE YOU REMOVE THE HEAD!!!
Tick Management • Cultural Control: Behaviour modification • Physical Control: Exclusion fencing • Biological Control • Host removal • Habitat modification • Chemical Control • Habitat treatment • Personal Protection • Host treatment
Chemical Control • Advantages • Rapid control, 97% within 24 hours • Cost effective • Less environmental damage • Disadvantages • Not tick specific • Relatively short term • Pyrethroids: Permethrin, Betacyfluthrin, Bifenthrin
Cultural Control • Avoid ticky habitat • Avoid good ticky times • After rain, high humidity • Wear light coloured clothing • Check oneself regularly during & after • Tuck pants into socks, shirts into pants • Remove clothing, place into hot dryer • Use repellents/permethrin on clothing
APVMA • Australian Pesticides & Veterinary Medicines Authority(National Registration Authority: NRA) • For insecticides/repellents, assess: • Human Toxicity • Product Efficacy • Environmental Impacts
Active Approved use Registered? Directions
= “Natural”“Organic” “Safe” & “Effective” Repellent Actives • DEET (N,N-Diethyl-meta-toluamide) • Picaridin • Lemon Eucalyptus Oil (PMD) • IR3535 • Citronella, melaleuca oil
Repellent Efficacy • Mosquitoes • Fradin & Day, NEJM (2002)
Permethrin Impregnated Clothing • Permethrin = toxicant not a repellent • Two forms: • DIY, ‘dip’ clothing • Impregnated fabrics (IF) • Studies show: • IF better protection than DIY • IF more washes than DIY • IF less environmental impacts • Permethin better protection than repellents • Widely used by armies
Registered • Equip • The Travel Doctor • Impregnation packs • 10ml/4L H2O, soak 2m • Effective 6 months
Human Safety • Risk analysis • What is worse: bites or repellents? • DEET first registered, 1957 • Billions of uses • Recommended by WHO & CDC • Only product recommended by CDC • US EPA: adverse reactions 1:100million • EPA: “permethrin factory-treated clothing is unlikely to pose any significant acute or chronic hazard to people” • “Naturals” are a greater risk to human health!!! Read & heed the label!