Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Compartmental models in epidemiology wikipedia , lookup
Mosquito control wikipedia , lookup
Epidemiology wikipedia , lookup
Hygiene hypothesis wikipedia , lookup
Gene therapy of the human retina wikipedia , lookup
Eradication of infectious diseases wikipedia , lookup
Tropical Ophthalmology. Part Three of Three Dr. Steve Waller Uniformed Services University of Health Sciences Bethesda, Maryland, USA [email protected] Unusual tropical eye diseases • Not commonly found in U.S., even in teaching hospitals • Five examples: – atypical tuberculosis (TB) – leprosy – manzanillo keratopathy – loa loa conjunctivitis – tarantula keratopathy Atypical TB – after LASIK or transplant, steroid gtts – incidence resurging Leprosy • neurotrophic cornea • entropion • can have uveitis in lepromatous disease Manzanillo tree sap keratopathy • Manzanillo or “beach apple” tree – common to Caribbean, east coast of Florida • Sap is milky latex vesicant known for delayed dermal effects; folk medicine for conjunctivitis • Acute ocular effects first described in US troops during WWII • Other natural blistering agents: – cantharidine (beetle) – no known antidote – poison ivy/oak – podophyllum (mandrake root) case seen in military hospital in San Antonio Vesicant toxicity to cornea Mustard gas: alkylation – crosslinks DNA and denatures protein – clinical effect: World War I scene, France • cornea edema • ischemia • secondary melt or ulcer Loa loa: the “eye worm” • Filarial nematode of West and Central Africa • mango fly (Chrysops), bites at dawn/dusk • 20 million infected, >30% in hyperendemic areas • adult worms live for 20 years, up to 60 mm long • subcutaneous or subconjunctival migration • “Calabar swelling” from allergic angioedema (named for eastern Nigeria seaport) Manifestations and life cycle • • • • pruritis, skin tracks fever meningitis larvae travel in vessels • mango fly stages • 1-4 years to mature Prevention, Diagnosis, Treatment • Prevention: avoid vector contact, apply insecticide to mango groves • Diagnosis: clinical or find microfilariae on Wright or Giemsa stains of daytime blood • Treatment: surgery, ivermectin*, albendazole*, mebendazole* * off label use Excision of subconjunctival loa loa worm Tarantula keratopathy • Uriticating hairs - dorsal abdomen • ‘Cloud’ of hairs easily rubbed off fine barbed hairs in cornea, can migrate to retina diagnose by history of exposure and pain without inflammation Zoonotic eye diseases • Preferred host is non-human • Paratenic (dead-end) visit by parasite, but damage still done! • Two examples: – Toxocara vitreoretinopathy – orbital myiasis Ocular larva migrans (Toxocara canis or cati) • Worldwide distribution • Risk factor: exposure to canine/feline feces • sandbox is infective up to one year after feces deposited Toxocara life cycle • • • • • adults in canine intestine fecal contact by human eggs hatch in GI tract migrate in blood vessels exits at end organ –brain, eye –liver –lungs Manifestations • Visceral larva migrans • Ocular larva migrans – Uveitis, hypopyon – Macular / peripheral granuloma – Vascular occlusive disease • Treatment – Steroids, laser if larva alive – Value of antihelminthics unclear Myiasis • Infestation of tissue or cavities by maggot (Diptera) • Internal: subretinal migratory tracks • External: lids or conjunctiva • Orbital: debilitated patient, abscess • Treatment is excision Dermatobia hominis • AKA human botfly, torsalo (Central America), ‘beef worm’ (Belize), ‘mosquito worm’ • Habitat: forests and river valleys in Latin America, imported to USA • case in Dallas County, TX, 2003 • Hosts: man, cattle, dogs, birds Dermatobia hominis • Life cycle of 3-4 months • Female attaches 15-30 eggs to a fly, mosquito, or (rarely) tick, who then transmit to egg to human host • 1mm ‘bot’ hatch, enter host at bite • grows over 6-12 weeks to 20 mm • Mature larvae exit furuncle opening, drops to ground, pupates for 14-24 days • Adult does not eat, mates within one day, and lives only one week Larva • Furuncular myiasis: movement often observed within opening • Two oral hooks at distal end, two dark respiratory ‘spiracles’ near skin break • Adult fly: ½”, yellow, resembles a bee Ophthalmomyiasis externa • Treatment: –Occlude breathing tube with beeswax, gum, ointment, fat, drop of nicotine –Excision –Subretinal larva: argon laser Iatrogenic Diseases • Rabies in corneal transplant – Most recent case - Iran, 1996 – 8 reported cases (one US case in 1979) – implications for regulation and eye banking in developed and developing world Acanthamoeba Keratitis • Ubiquitous, warm water • Homemade contact lens solutions and hot tubs • Chronic pain and ulcer • Medications (all off label use): Brolene (0.1% propamidine), PHBG 0.02% , neomycin, miconazole, others trophozoite and cyst clinical appearance radial keratoneuritis: infiltrate along radial corneal nerves Signs and symptoms • pain out of proportion to findings • paracentral ring infiltrate • prior medical failure or diagnosis of HSV Working Together • International partnerships are key! • Address the cultural gap in research – Common understanding of disease – Common understanding of ‘science’ The good news • Increasing access to eye surgery • Inexpensive intraocular lenses now available worldwide • Ivermectin and the UN’s Onchocerciasis Control Program • Improving nutrition • Increasing opportunities for service Summary • Epidemiology: still much needless suffering around the world • Synergy: culture and disease • Environment: protection is affordable • Exotics: rare but important • Iatrogenics: preventable • The future is bright Questions? [email protected]