Arthropods Of Medical Importance (1/2)

Zoo 173 Intro to Parasitology Parasitic Insects Parasitology Lecture Subphylum Crustacea Subphylum Uniramia Subphylum Chelicerata

Phylum Arthropoda

Suphylum Uniramia Class Myriapoda – no parasitic species Class Hexapoda Subclass Myrientomata – no parasites Subclass Oligoentomata – no parasites Subclass Diplurata – no parasites Subclass Pterygota – “Winged Insects” Order Mallophaga – Biting Lice Order Anoplura – Sucking Lice Order Hemiptera – True Bugs Order Siphonaptera – Fleas Order Diptera – Flies, Mosquitoes Hexapoda: Insects Three pairs of legs, one pair antennae, distinct head, thorax, and abdomen. Mouthparts vary Biting Sucking Two types of development Hemimetabolous Several larval nymph stages Each nymph looks more like the adult No sudden, dramatic change Holometabolous Several nymph stages looking nothing like adult Enter a non-feeding, pupal stage to turn into adult Metamorphosis Parasitic Insects Ectoparasites Temporary Permanent Some feed on skin, hair, and feathers Take blood only accidentally Mallophaga Many suck blood Solenophage Insert mouthparts into a blood vessel to withdraw blood Anoplura, mosquitos Mouthparts cut skin and vessel Feeds on a pool of blood that collects Black flies, deer flies 2800 species Ectoparasites on birds Few species on mammals

Mallophaga – Biting Lice

1 of 18

Wingless, with reduced or no eyes Chewing mouthparts Most eat feathers, hair or bits of sloughed skin Some pierce skin or feather shafts Feed on blood Tarsal claws are enlarged For clinging to hair and feathers 2 claws on bird parasites 1 claw on mammal parasites Development is gradual (no metamorphosis) Vector for no human diseases Vector for filarial nematodes of birds Particularly in coots, grebes and parrots Serious pest in aviculture Menacanthus stramineus Yellow body louse of poultry Can occur in large numbers 35,000 on one bird Can disrupt feeding results in lower egg production Other species in poultry Goniocotes gallinae – fluff louse Lipeurus caponis – wing louse Cuclotogaster heterographus – chicken head louse Chelopistes melagridis – large turkey louse Bovicola bovis Louse of cattle Trichodectes canis Common on dogs Can be I.H. for Dipylidium caninum Felicola subrostrus Common in cats Haematomyzus elephantis Found on elephants Can cause dermatitis Anoplura – Sucking Lice Only 500 species Ectoparasites on mammals only Including humans Sucking mouthparts Feed on blood Solenophage Important vectors of disease in humans and domestic animals Important pests in agricultural settings Haematopinus suis Louse of pigs

A.K.A. cooties, nits (eggs) Definitive Host: Humans Rarely pigs Intermediate Host: None Geographic Distribution: Cosmopolitan Location on D.H.: Two distinct forms

Pediculus humanis

2 of 18

Head Lice P.h. capitis Found on head Body Lice P.h. humanus Found on body and in clothes Visit body only to feed Lay eggs and spend time in clothes Descended from common ancestor Not yet separate species Will breed but reduced fertility Mode of transmission: Usually direct contact between individuals including brushing against someone Also exchanged on brushes, hats, combs, clothing, bedding, etc. Pathology and Symptoms: Pediculosis Very little pathology Louse inserts mouthparts into skin and sucks blood. Small red papule develop around bite Causes itching which may lead to secondary bacterial infection Untreated, it can lead to matting of the hair Fungus grows in the hair, making it smelly. Chronic infestations can lead to darkened, thickened skin Vagabond’s disease Social stigma Can be found in very clean children Particularly common in crowded conditions Institutions Classrooms War / Refugee camps Allows for passing of the lice between people easier Vector for several diseases Louse-borne Typhus, Trench Fever, and Relapsing fever Particularly body lice Lice-borne Typhus Caused by Rickettsia prowazekii, a bacterium Transmitted mostly by body lice Epidemics are very common in pre- and post-war situations. Crowding, stress, poverty and mass migration of people Very important in shaping the history of Europe in the last century. Killed Christian and Moorish armies in Spain during 1489-90 1528 epidemic reduced French army from 25,000 to 4,000 Resulted in Spanish dominance in Europe for more than century Very deadly, mortality may reach 100% in humans It also kills the louse Bacteria are transmitted in the feces of the louse. Humans contract it by rubbing louse feces into wound or eye Can also inhale it in louse feces Disease starts with high fever that continues for about two weeks Continues to malaise, vertigo, loss of appetite, and stupor Fifth or sixth day, rash appears in armpits and on flanks the spreads to chest, abdomen, back, and extremities and stays for several weeks Rarely found on palms, soles, and face After second week, stupor clears and patient either recovers or the bacteria attacks CNS and patient dies. Treated with antibiotics

3 of 18

Both Ricketts and Prowazek, pioneers researching typhus, died from it. Lice-borne Typhus - Epidemiology As patient’s fever increases, louse leaves the body Spread disease to next person Person can also catch typhus by inhaling louse feces People who recover from the disease are infective to the lice for several years. Flying squirrels are reservoir hosts Becoming popular pets

Trench Fever Caused by Rochalimaea quintana, a rickettsial bacteria Transmitted by body lice only. Epidemics occurred during both World Wars Not fatal but very debilitating. Does not kill the louse either so louse remains infective for life. Humans may have bacteria in blood for eight years after recovery Person doesn’t develop symptoms for 10-30 days after exposure Then they experience headache, body pain, and malaise. Temperature then rises to 40C Accompanied by headache, pain in back and legs, dizziness, post orbital pain in eyes Typhus-like rash appears but disappears in 24 hours Recovery is slow and relapses are frequent. Tetracycline use for treatment Relapsing Fever Caused by Borrelia recurrents, a spirochete bacteria Transmitted by body lice Picks up spirochete with blood meal Human contracts bacteria when crushes louse. Bacteria enter abraded skin or may penetrate skin Mortality is usually low. Can reach 50% in undernourished populations Has disappeared from U.S. Small foci in South America, Europe, Africa, and Asia Indistinguishable from tick-borne relapsing fever caused by another Borrelia. Incubation period is 2-10 days Sudden onset of headache, dizziness, muscle pain, and fever. Rash appears, usually around neck and shoulders then down to abdomen and chest. Patient is severely ill for 4-5 days then feels better for 3-10 days then another sudden attack. Cycle may repeat several times Antibiotics are effective but cause serious side effects. Frequently co-occurs with Lice-borne Typhus Control of lice There are many commercial preparations that are effective against lice. Shampoos kill the adults Special combs remove the nits (eggs) from the hairs Most contain permethrin Permethrin-resistance is developing Kerosene and other petroleum products are not effective Good hygiene practices usually reduces the spread of lice Ordinary laundering of clothing 4 of 18

Not sharing hats, scarves, combs, brushes, etc. Phthirus pubis – Crab louse Definitive Host: Humans Intermediate Host: None. Geographic Distribution: Cosmopolitan Location in D.H.: Usually on hairs in the pubic area Can be located in the armpits. Rarely in beard, mustache, eyebrows, and eyelashes Mode of transmission: direct contact with infected body part. Pathology and Symptoms: Causes “crabs” Bites cause itchy, weepy welt Less active than head and body lice Frequently keeps mouthparts in skin for some time Bites are usually more irritating Not a vector for any disease. Can be treated with the pesticide-laced shampoos and combs used for head lice. Other important Anoplurans Haematopinus suis Normally found on pigs Can live on humans Vector for hog cholera H. eurysternus and H. quadripertusus Lice on Cattle H. asini is lice of equines Solenoptes capillatus found on cattle Linognathus sp. Many species that infect cattle, sheep, goats, and dogs Pediculus mjobergi Lice in New World Monkeys

Hemiptera –True Bugs One of the largest insect orders Over 55,000 species Hemimetabolous Nymphs look similar to adults Most are free-living, non-parasitic Have sucking mouthparts Most suck plant juices Few feed on blood Mostly in familes Cimicidae and Reduviidae Family Cimicidae Small, wingless bugs Feed on blood of birds and bats Of 22 genera, 12 are parasites of bats Bird hosts are species that usually nest in caves Exception is Oeciacus vicarius which inhabits swallows nesting in colonies Three species occur in humans Probably from when we dwelled in caves Bed bugs 5 of 18

Three species occur in humans. Cimex lectularis Cosmopolitan but most common in temperate zones Cimex hemipterus More tropical Leptocimex boueti West Africa Stay on host only 5 to 10 minutes to feed at night Spend rest of time in bed or crevices in house Do not carry disease Very irritating Can cause anemia Bites may cause allergic reaction Can survive up to 18 months Bed bugs - control Live in seams of mattresses, box springs, wooden bedsteads, cracks in walls, and behind wallpaper May be some distance from host Can be moved from one site to another by used furniture Only one female needed to create new infestation Application of residual insecticides can control bedbugs Cleanliness also helps Follow temperature or carbon dioxide gradient to find host

Family Reduviidae A.K.A. – Kissing bugs Most feed on insects Assasin bugs Reduvius personatus eats bedbugs! Most can bite humans usually used only in defense Subfamily Triatominae Specialize in biting animals and taking blood meals Not very host specific Species that feed on humans will also feed on dogs, cats, rats, and other animals in the house Live in the habitat of the host Including human dwellings Subfamily Triatominae Important vectors of Trypanosoma cruzi Chagas’ disease All Triatomines are suitable hosts for T. cruzi. But differ in susceptibility Studied 11 species Dipetalogaster maximus and Triatoma rubrovaria pass the most trypomastigotes Triatoma vittceps passed the fewest. Also depends on its domesticity Panstrongylus megistus, Triatoma infestans, T. dimidiata, and Rhodnius prolixus are most important vectors Live in human dwellings Control Reduce living spaces for bugs Replace thatched roof with roof tiles or sheet metal Cover dirt floors

6 of 18

Remove stacked firewood from side of house Reduce alternate foods like rats, dogs, and cats Residual insecticides around hiding places Southern Cone Initiative South and Central America Reducing incidence of T. cruzi Killing bugs and limiting hiding places Testing blood donors for T. cruzi Found throughout the U.S. from New England to California Trypanosoma cruzi is also found throughout the U.S. in wildlife Including wood rates, raccoons, opossums, and skunks Only a few human cases of Chagas’ disease occur annually Particularly in Arizona Order Siphonaptera: Fleas 2500 species Most are less than a millimeter to a few millimeters long Most are parasites of mammals About 100 species occur on birds Wingless Adults feed exclusively on blood Piercing/sucking mouthparts Larva are usually not parasitic, feeding on debris in nests or other habitats or on feces of adults Holometabolous development Larvae undergo metamorphosis Amazing jumping ability Xenopsylla cheopis can jump more than 100 x body length Ctenocephalides sp. have vertical jump of 33 cm Equivalent to you jumping 800 feet into the air Due to unusual structure inherited from winged ancestors Resilin is a very elastic protein Releases 97% of stored energy instantly Compared to 85% in rubber Found where the wings used to be joined to the body, now attached to hind legs Flea “cocks” its hind legs and walks rests on front four Stretches the Resilin and stores the energy Flea just has to make small muscle movement of back legs to release cocked resilin Live in the host’s lair Nests Carpets Bedding Can survive long periods without food P. irritans – 125 days X. cheopis – 38 days Can survive long periods when feed regularly P. irritans – 513 days X. cheopis – 100 days Require high humidity Most fleas lay eggs on body of host They usually fall off into the nest/lair Two genera have reproductive cycles closely tied to host Spilopsyllus sp. and Cediopsylla sp. Relatively sedentary Attaches to hosts (usually rabbits) ears

7 of 18

About 10 days before female gives birth, fleas become sexually mature When rabbit gives birth, fleas migrate to females face then leap onto newborns Mate and lay eggs on young Return to female after laying eggs Most fleas are not very host specific But they do have preferred hosts Transfer easily to another host of another species Name usually refers to the preferred host Pulex irritans – Human flea Ctenocephalides canis – dog flea Ctenocephalides felis – cat flea 19 species bite humans in the U.S. Over 50 genera have been found to be potential vectors of human diseases Particularly Plague Vary in how much time they spend on host Some rodent fleas are seldom on the host but are abundant in the nest Conorhinopsylla and Megarthroglossus Most spend most of their time on host as adults but transfer easily to another host Females of the sticktight flea, Echidnophaga gallinacea, attach permanently to host skin The female of Tunga penetrans burrows beneath skin and becomes endoparasite Larvae of Uropsylla tasmanica are endoparasites under the skin while adults live on skin of host (Tasmanian Devils). Glaciopsyllus antarcticus spends entire adult lives on hosts, ocean-going birds Family Ceratophyllidae Northern Rat Flea Nosopsyllus fasciatus Common in domestic rats and mice Probably spreads plague between rodents Ground Squirrel Flea Diamanus montanus Common in wild rodents in western U.S. May spread plague between wild rodents Western Chicken Flea Ceratophyllus niger Will bite humans European Chicken Flea Ceratophyllus gallinae Parasitizes wide variety of birds Family Pulicidae Most important medically as vectors for plague Human Flea Pulex irritans Found on pigs, dogs, coyotes, prairie dogs, ground squirrels, burrowing owls Seems to prefer dogs to humans Very important vector for plague Sticktight flea Echidnophaga gallinacea Burrows mouthparts into skin and stays on host Prefers chickens but occurs on ears of dogs, cats, horses, rabbits and other animals, including humans Can cause death in heavy infestation Dog Flea

8 of 18

Ctenocephalides canis Cat Flea Ctenocephalides felis More common on dogs than dog flea in N. America Wide range of mammals including humans, horses, skunks, foxes, mongooses, koalas, and poultry Very annoying pest of humans Non-pathenogenic Rarely carry plague Can cause allergies Flea feces have over 15 allergens About $1billion dollars per year spent on flea treatments Found throughout U.S. except mid- to north- Rocky Mountain areas Oriental or Tropical Rat Flea Xenopsylla cheopis Cosmopolitan distribution, except cold climates Found in the U.S. as far north as New Hampshire, Minnesota, and Washington (state) Usually found on Rats (Rattus sp.) Most important vector of the plague in humans Also important vector of murine typhus Family Tungidae Tunga penetrans A.K.A. sand flea, chigoe, jigger Female burrows into skin and engorges on blood When she crawls in, she is barely 1mm long Expands to size of pea Male mates with her through hole is skin she leaves She lays eggs in cavity and larvae crawl out after hatching Tunga penetrans Original range was Central and South America and West Indies Introduced to Africa and spread to India Can occur in humans Particularly under the nails and on the feet Called jiggers because causes people to “jig” about Also found on dogs, particularly between the pads of feet Causes nasty ulcerations and very itchy allergic reaction Tetanus and gangrene are occasional complications Autoamputation can also occur Surgical removal is the only treatment Prevention by wearing shoes Plague A.K.A. Black death or Bubonic Plague Caused by bacterium Yersinia pestis (aka Pasturella pestis) Bacteria releases toxins Toxins act on the mitochondria Some animals are mores sensitive to toxins than others Rats, mice, and humans are sensitive Dogs, monkeys, and chimpanzees are not Rodents are reservoir hosts Most, if not all, populations of rodents are infected Fleas are vectors Particularly Xenopsylla cheopis Transmitted in blood meal

9 of 18

Very important disease in human history Major outbreaks in 6th, 14th and 17th century in Europe. 90% of people exposed died! Pandemic in 14th century killed ¼ the population of Europe, 25 million people Last pandemic was 1895-1908 Started in Orient then spread throughout world Most common in port cities Incidence around the world is declining Between 1900-1957, 941 cases in U.S. with 711 fatalities (75%) Between 1958-1972, there were only 51 cases in U.S. with 9 fatalities (17%) Not clear why there has been a decline Three forms of plague: bubonic, primary pneumonic, and primary septicemic Bubonic plague Starts with buboes Occurs in only 75% of cases Hardened, swollen lymph nodes10 As large as chicken eggs May rupture to the outside Most common type in epidemics About 25% to 50% fatalities Primary Pneumonic Rapidly moves to the lungs Causes pneumonia-like symptoms Highly contagious Coughing, sneezing or talking spreads bacteria in saliva spray Primary Septicemic Systemic blood disease with little or no lymph node swelling Can cause parts of body to become black and necrotic Hence the name Black Death Can also develop secondarily in bubonic and primary pneumonic plagues Both forms are usually fatal Incubation period is 2-4 days after flea bite Starts with rapid rising fever up to 40C Lymph nodes draining area near bite swell and become necrotic Damage to vascular and lymphatic endothelium leads to petechial diffuse hemorrhages. As disease progresses, there is mental dullness, followed by anxiety or excitement, then delirium, lethargy, and coma. Untreated, person usually dies in less than five days Only three days in primary septicemic plague If patient recovers, fever drops in two to five days Treatment is with antibiotics and antitoxins Vaccination available if traveling Campestral plague Associated with open country, not woodlands or towns. Rarely causes epidemics Widespread in wild rodents and rabbits in western U.S. People are exposed when they handle wild animals Most cases are from New Mexico One case in California was due to hunting ground squirrels Hunter contracted bubonic plague with secondary pneumonic plague Spread to 13 other people, 12 of whom died Several cases have been associated with skinning, cooking, and eating wild rabbits and hares when they are bitten by the rabbits fleas

10 of 18

Although the disease in humans is in decline, we don’t know why Has always been a cyclical disease Long periods of low incidence followed by epidemics Clearly still common in rodents in the wild We don’t know when or where the next outbreak will occur Murine Typhus A.K.A. Flea-borne Typhus Caused by Rickettsia mooseri Can infect wide range of mammals, including opossum Most important reservoir is Norway Rat Rattus novegicus Causes mild fever in humans for 14 days Includes chills, severe headaches, body pains and rash More severe in the elderly Transmitted by flea bite or by rubbing flea feces into wound Very common in U.S. before 1945 Rat and flea control has reduced incidence Hyperparasitism Dipylidium caninum Uses C. felis, C. canis and P. irritans as I.H. Trypanosoma lewis Parasite of rodents Uses N. fasciatus as a vector Hymenolepis nana and H. diminuta Can develop in X. cheopis, C. felis, C. canis and P. irritans Dipetalonema reconditum Filarial worm of dogs Uses C. canis and C. felis Control of fleas Important to prevent/reduce diseases they carry Keep house clear of debris where they can live Particularly carpets and pet bedding Use persistent insecticides on carpets Air conditioners/dehumidifiers Light-traps, yellow-green filters may work Insect repellants offer some protection Oral and topical treatments for pets have been developed Insect growth hormone inhibitor Dips and shampoos need to repeated frequently because dogs and cats are frequently reinfected outside. Keep debris outside to a minimum

Order Diptera: Flies Over 120,000 species in 140 families 15 families have parasitic species Most important order medically Important vectors for many diseases and parasites Characterized by having only one pair of wings Holometabolic development Larval stages (maggots) look very different than the adults Undergoes complete metamorphosis Suborder Nematocera Family Psychoidae – moth flies and sand flies Family Culicidae – Mosquitoes Family Simuliidae – Black flies 11 of 18

Family Ceratopogonidae - biting midges Suborder Brachycera Family Tabanidae – deer fly, horse flies Family Chloropidae – eye gnats Family Glossinidae - Tsetse flies Family Hippoboscidae – Louse flies Families Streblidae and Nycteribiidae – bat flies, bat spiders Family Fanniidae – Latrine flies Family Muscidae – House Flies Family Calliphorida – blow flies Family Sarcophagidae – flesh flies Family Oestridae – bot flies

Family Psychodidae Two groups Subfamily Psychodinae Moth flies Little medicinal importance Breed around sewage and cesspools Subfamily Phlebotominae Sand flies Females feed on blood Telmophage Males feed on plant juices Vectors for Leishmania sp., Carrion’s disease, and sand fly fever Sand Flies Three important genera Phlebotomus and Sergentomyia in the Old World Lutzomyia in the New World Weak flyers Most active at night or twilight Inactive if there is any wind Usually avoid hot, dry places Few desert species are active when it is humid, hiding during the day Coincides with the activity pattern of humans in the area. Carrion’s Disease Caused by Bartonella bacilliformis, a bacteria Most common in Ecuador, s. Columbia, and Andean region of Peru Two clinical forms Oroya fever Sometimes fatal, visceral form with bone, joint, and muscle pains, anemia, and jaundice Verruga peruana Mild, nonfatal cutaneous form Named after Daniel Carrion who studied the disease Injected himself with the bacteria from a patient with verruga peruana Developed Oroya fever Just before he died, he realized they were caused by the same organism. Sand Fly Fever A.K.A. Papatasi or Three-day Fever Transmitted by Phlebotomus papatasi and P. sergenti. Occurs in Mediterranean, eastward to central Asia, southern China, and India Nonfatal, viral disease of short duration. Long convalescence 12 of 18

Epidemics can occur Family Cuculicidae - Mosquitoes Most important vector of human disease Extremely important economically Feed on birds, mammals, reptiles and amphibians Over 3500 species, including 150 in North America Mosquito life cycle Females feed on blood Males do not Eggs are usually laid in water Larval and pupal stages develop in water Connected to surface with air tube Pupa is actually active Adult female lives 4-5 months during hibernation, but 2 weeks during summer Males can live up to 1 month

Mosquitoes Understanding behavior is important in controlling them and the diseases they transmit Some are very host specific, others are not Some feed at night, others during the day Some breed and feed close to humans, others far away Species vary in their susceptibility to the pathogens they transmit Appears to be a genetic resistance Culex sp. Mostly feed on birds Important as vectors of bird malarial parasites Overwinter as inseminated females Culex tarsalis Widespread and common in semiarid western U.S. and southern states to Indiana Vector for Western Equine Encephalitis (WEE) and St. Louis Encephalitis (SLE) May also transmit West Nile Virus Culex pipiens Common house mosquito Found worldwide around humans Lay eggs in all sorts of small water bodies Enters house at night to bite Vector for SLE, Wucheria bancrofti, Dirofilaria immitis, avian pox, and several avian malaria Probably a vector of West Nile Virus Aedes sp. Noted for their ferocity Feed during day or crepuscular (dusk and dawn) Aedes dorsalis and Aedes vexan most common species in the U.S. Aedes sollicitans Flood water mosquitoes in eastern 2/3 of the U.S. Snow-water mosquitoes Females lay eggs in summer where they will be covered next spring by snow melt Aedes taeniorhynchus Black Salt marsh mosquito Aedes triseriatus Tree-hole breeder east of the Rockies

13 of 18

Vector of LaCrosse Encephalitis Aedes albopictus Asian Tiger Mosquito Will breed in small containers Introduced to U.S. Important vector for dengue, dengue hemorrhagic fever, equine encephalitis, yellow fever, and LaCrosse Encephalitis Aedes aegypti Tree-hole breeder Adapted to breed in small pools near humans Very important vector for disease Wide distribution from 40oN to 40oS around world Originated in Africa and spread with slave trade Most important vector for Dengue and yellow fever Yellow Fever Caused by Flavivirus Frequently fatal disease Vaccines are now available Caused several epidemics after introduction to New World Anopheles sp. Eggs are laid on water Most breed in stagnant mangrove swamps, sunny pool, edges of trickling streams. Feed with body slanted away from host. Very important vectors of human malaria Primary vectors in U.S. were A. quadrimaculatus and A. freeborni. Mosquito control Eliminate breeding sites Used tires, cans, other trash that holds water Tree-holes Use copper-lined vases for cemetery flowers Biological control Mosquito fish (Gambusia affinis) eat larvae Great for outdoor ponds and animal water troughs Larval mosquitoes of Toxorhynchites genus eat other mosquito larvae Nematode parasites Insecticides Many environment costs Resistance develops Black Files, Buffalo Gnats May be tan or gray Female feed on blood or plant nectar Males feed on plants only Most numerous in north temperate and subarctic zones Larval development only in running, well-oxygenated water. Much more common around seeps, streams, and rivers Takes about 7-12 days Some over winter as larvae Family Simuliidae Simulium is the largest genus More than 1200 species Prosimulium and Cnephia are found in North America

14 of 18

Most are host specific and few bite humans But those that do are very annoying Take a chunk of skin and muscle Can cause a nasty reaction if person is allergic They can actually cause the death of cattle because they are so numerous Family Simuliidae Particularly sensitive people may suffer Black Fly Fever Combination of nausea, headache, fever, and swollen limbs Vector for Onchocerca volvulus Cause of river blindness Mostly Simulium sp. Also vector of many non-human diseases Onchocerca gibsoni Infects cattle Results in low-quality leather and losses in cattle industry Leucocytozoon sp. Causes avian malaria DEET-based sprays are usually effective to prevent bites The flies will still annoy you. Family Ceratopogonidae Biting midges, punkies, no-see-ums Less than 1 mm long Can enter house through screens Only females feed on blood Most feed on other insects and ectothermic vertebrates Four genera bite mammals, including humans Larval can develop in moist soil as well as in water and salt water Take six months to one year to complete development Largest genera is Culicoides Over 1000 species Some bite humans Can affect tourism in infested areas Several are agricultural pest Vector for Mansonella nematodes in humans Vector for Leucocytozoon, Haemoproteus in birds, Vector for Onchocerca gibsoni in cattle, O. cervicalis in horses, and other filarial worms. May be a vector for encephalitis Vector for bluetongue Fatal disease in sheep and cattle Caused by Orbivirus Order Diptera Suborder Nematocera Family Psychoidae – moth flies and sand flies Family Culicidae – Mosquitoes Family Simuliidae – Black flies Family Ceratopogonidae - biting midges Suborder Brachycera Family Tabanidae – deer fly, horse flies Family Chloropidae – eye gnats Family Glossinidae - Tsetse flies Family Hippoboscidae – Louse flies Families Streblidae and Nycteribiidae – bat flies, bat spiders Family Calliphorida – blow flies Family Sarcophagidae – flesh flies Family Oestridae – bot flies 15 of 18

Family Tabanidae Horse Flies, Deer Flies About 4000 species Tabanus - horse flies Chrysops – deer flies Females take blood meal Take chunk of skin and feed on pool of blood Bite is painful trigger little reaction Serious pest to humans and livestock Vector for Loa loa Trypanosoma evansi and T. theileri Elaeophora schneideri Hog Cholera Anthrax Family Chloropidae Eye Gnats Look like tiny house flies Buzz around head and try to land on eye Lap up eye secretions Develop in soil May be mechanical vector of pink eye (bacterial conjunctivitis)

……… Family Glossinidae Tsetse flies Glossina only genus Of 23 species, only 3 are not vectors for Trypansoma brucei Found in Africa and Arabian peninsula Both sexes take blood meals Telmophagous Do not lay eggs Female gives birth to single, completely developed larvae Feed in oviducts on specially produce milk Larvae then burrow into soil and pupate Family Hippoboscidae Louse flies Both sexes take blood meal. In most species, males have wings, females wingless Females give birth to larvae that are ready to pupate Some spend entire life cycle on same animal Most are parasites of birds and mammals Only a few bite humans Family Hippoboscidae Pseudolynchia canariensis parasite of pigeons Vector for Haemaproteus columbae Melophagus ovinus Sheep ked Larvae cement themselves to wool to pupate Spends entire life on animal 16 of 18

Heavy infestations cause emaciation, anemia Also bites sheep shearers Bat flies Poorly known Strebilids 6 species in North America New World Bats Nycteribiids Bat spider flies Look like 6-legged spiders 5 species in North America Old World Bats

Families Streblidae and Nycteribiidae

Family Muscidae House flies Most are not parasitic Do not ingest blood Important carriers of disease Body construction favors carrying bacteria and parasite eggs/cysts Relish human food and human waste Live close to humans and enter houses Can transmit typhoid fever, cholera, polio, hepatitis, salmonella, anthrax, leprosy, and even eggs of Ascaris lumbricoides Stomoxys calcitrans Stable fly Cosmopolitan Both sexes feed on blood Can occur in great numbers Can transmit many livestock diseases Including brucellosis, relapsing fever, equine swamp fever, etc. Vector for the horse stomach nematode Habronema microstoma Myiasis Infection by fly maggots Usually have opening so insect can get oxygen Discomfort of host varies by species of fly Caused primarily by three families Calliphoridae – bot flies Sarcophagidae – flesh flies Oestridae – skin bots and warbles May be obligate or facultative. Maggots can be used in therapy Eat necrotic tissue and leave the healthy tissue alone Used in World War I to clear wounds Reduces infections in the wounds and speeds healing of wound Family Calliphoridae Blow Flies Primary niche is to digest dead tissue Most are facultative parasites Enter wounds created by other means Feed on debris in the wound Protocalliphora spp. Important parasite of birds 17 of 18

Cochiliomyia hominivorax Primary screwworm Obligate Most important cause of myiasis in humans Enter a wound already present on skin

Family Sarcophagidae Flesh Flies Most larvae are facultative parasites of invertebrates Wohlfartia vigil and W. opaca are important causes of cutaneous myiasis in U.S. Larvae penetrate the skin Most common in infants left unattended outdoors Creates a nasty boil in skin Family Oestridae Skin Bot Flies, Head maggots, cattle grubs, ox warbles, heel flies, stomach bots Larvae penetrate the skin Dermatobia hominis is the most common skin bot in humans Lay egg on other parasite When other parasite feeds, egg hatches and larvae drops onto skin Common from Mexico through South America Cuterebra most common skin bot in wild animals Can infect humans Family Oestridae Head Maggots develop in sinuses and nasal passages of hoofed mammals Oestrus ovis – sheep bots Stomach bots Found in horses, rhinos, and elephants Eggs are laid on hairs Hatch when they are licked up by host Burrow into tongue, down to stomach, and become endoparasites Pass out in feces and pupate in soil All myiasis can be fatal if larvae infect brain

18 of 18