Published on October 23, 2007
Class Insecta: Class Insecta Class Insecta is the largest class of animals. Characteristics: 1. 3 body parts - ________________________________ 2. _______________________________ contains pair of compound eyes, ocelli, and 1 pair of antennae. 3. ____________________________ possesses 3 segments, each with a pair of legs. Wings may or may not be present; extend from last 2 segments if present. Slide2: Characteristics cont: 4. Abdomen contains ________________________________ - insects are ___________________________________ 5. Possess 2 types of metamorphosis: a. ________________________ egg nymph adult b. ________________________egg larva pupa adult Class Insecta contains some 26 orders, 5 of which are important in parasitology. Insects with Incomplete Metamorphosis: Insects with Incomplete Metamorphosis ORDER MALLOPHAGA - ____________________________________ Ectoparasites of birds and mammals - feed on _______________________________________ None infest humans. One species of veterinary importance: Trichodectes canis - ______________________ _________________________________________ Characteristics: wingless; head is wider than thorax; tiny 1st pair of legs - heavy infestations can cause hair loss in puppies - intermediate host of ______________________ _______________________________________ ORDER ANOPLURA : ORDER ANOPLURA _____________________________________ - mouthparts modified to suck blood of their host. Head is narrower than thorax. Ectoparasites of mammals only. 2 species occur on humans Pediculus humanus: Pediculus humanus Human head and body lice. Also known as "cooties", “graybacks,” and “mechanized dandruff". 2 subspecies: Pediculus humanus humanus - Pediculus humanus capitis - Pediculus humanus: Pediculus humanus Morphology: Adult is 2-3 mm in length. Body is dorsoventrally flattened with head narrower than thorax. 3 pairs of legs are similar. Male is recognized by posterior copulatory structure called the _____________________ MALE FEMALE Life Cycle of Pediculus humanus: Life Cycle of Pediculus humanus Incomplete metamorphosis: egg (= nit) nymph adult Female cements nits to clothing fibers or hairs. Eggs hatch into nymphs (immature adults). Nymphs undergo 3 molts and become adults in 8-9 days. Life Cycle of Pediculus humanus: Life Cycle of Pediculus humanus TRANSMISSION of lice from person to person is associated with crowding of infested people (i.e. prisons, institutions, schools, etc.) - Outbreaks in Eau Claire schools Any stage can be transmitted from one person to another. - Nits can be transmitted by use of another's comb - Nymphs or adults can move from one clothing article to another in a crowded cloakroom Importance of Pediculus humanus: Importance of Pediculus humanus 1. _______________________ _________________________ A localized inflammation and itching occurs at bite site from salivary secretions and louse feces rubbed into wound. 2. Vector of _________________________________________ - causative agent is bacterium Rickettsia prowazekii Louse-borne Typhus – vectored by Pediculus humanus: Louse-borne Typhus – vectored by Pediculus humanus Pediculus picks up bacterium Rickettsi prowazekii when feeding on infected person. Rickettsiae multiply in louse's digestive tract & are released in louse’s ______________________. Rickettsiae are transmitted to a human when the _____________________________________________________ Louse is sensitive to ____________________________ of infected host and will leave that person for another with normal temperature. Thus, the disease is transmitted from an infected person to a non-infected person and can occur in epidemic proportions. Louse-borne Typhus: Louse-borne Typhus Large outbreaks of louse-borne typhus have been associated with ________________________ where mass migrations of refugees, poverty, and crowding in prison camps have resulted in epidemics. The refugees of Rwanda and Burundi have fallen victim to typhus Louse-borne Typhus: Louse-borne Typhus Disease is characterized by a high fever, body rash, and CNS destruction. Mortality rate can reach _______________ in epidemics. Treatment with the antibiotic _________________________ Phthirus pubis: Phthirus pubis Common names: ________________________________________________ Adults have short, wide body - 1.5 to 2 mm long Last 2 pairs of legs are much larger than the first pair. Hairy processes on abdomen ________________________ on male Phthirus pubis: Phthirus pubis Tarsi at the ends of 2nd and 3rd pairs of legs are large and adapted for attachment to human hair. Crab lice are adapted for life in ____________________ ______________________ of humans - i.e. in pubic region, arm pits, beard, and eyebrows. Phthirus pubis: Phthirus pubis Life cycle stages: Importance of Phthirus pubis: Importance of Phthirus pubis Bite causes intense itching but NO diseases are transmitted by it. Transmission is by close body contact i.e. sexual intercourse French name for crab louse is "papillion d'amour" - meaning? In Eau Claire, I seem to find them always on one group of humans. Any idea what this group might be? Phthirus pubis: Phthirus pubis SEM of crab louse - photo taken by my graduate student who found in on a “friend” Hairy lateral processes One Louse of Veterinary ImportanceHaematopinus suis - pig louse: One Louse of Veterinary Importance Haematopinus suis - pig louse Large louse on pigs; will bite humans if available - recognized by large size - 4 mm long - elongate head - round abdomen with distinct lateral abdominal plates __________________ Haematopinus suis - pig louse: Haematopinus suis - pig louse Causes severe infestation of pigs - irritation, weight loss, and anemia in heavy infestations - economic loss to pig farmer Other species of Haematopinus occur on _______________________________ Control of Human Lice - both species: Control of Human Lice - both species Delousing involves use of insecticide - in WWII DDT dust was used - today lotions or shampoos containing _________________________________ are used - common one is "Rid" - all stages of lice are killed with this insecticide Problem: _____________________________ _____________________________________ Good personal hygiene and laundering of clothes in hot water also helps keep down the lice population. Delousing can also be accomplished by ___________________________: Delousing can also be accomplished by ___________________________ ORDER HEMPITERA - Chapter 36: ORDER HEMPITERA - Chapter 36 ____________________________________ Two families of medical importance. FAMILY REDUVIIDAE - Assassin bugs, kissing bugs, vinchucas Vectors of _________________________________ caused by _________________________________ in Central and South America. FAMILY CIMICIDAE - ____________________________: FAMILY CIMICIDAE - ____________________________ Cimex lectularius - Cosmopolitan in distribution. Morphology - wingless, reddish brown bug - 5-8 mm in length Adults are recognized by broad first segment of the thorax called the __________________________ 3 pair of legs are thin and modified for running. Cimex lectularius: Cimex lectularius Males are easily recognized by fang-like __________________________at the posterior end of abdomen. Copulation is by traumatic insemination. Females are identified by presence of ___________________________ in the 5th abdominal segment. Life Cycle of Cimex lectularius: Life Cycle of Cimex lectularius ______________________________ metamorphosis Eggs hatch into ____________________ which must take blood meal before molting into ______________________ Both males and females are blood feeders. Mouthparts are modified to suck blood from the dermis layer of the skin. Takes a bedbug 10 to 15 minutes to take a blood meal. Life Cycle of Cimex lectularius: Life Cycle of Cimex lectularius Bedbugs are ____________________________ and emerge from daytime hiding places in bedding, mattress, walls, etc. to feed usually before dawn. Bites cause little reaction in some persons to considerable inflammation in others due to allergic reaction to bug's saliva. Other problem: _______________________________________ Diseases are transmitted by bedbugs: ______________________ They are controlled by spraying insecticides in areas where they rest during the day. Insects with Complete MetamorphosisORDER SIPHONAPTERA - fleas - Chapter 37: Insects with Complete Metamorphosis ORDER SIPHONAPTERA - fleas - Chapter 37 Fleas are small insects which have had a tremendous impact on human civilization. Fleas are vectors of ____________________________ which has killed millions of persons from the dawn of civilization until today. Pandemic (world-wide epidemic) occurred in 1500’s and killed 1/4 of the world’s population - 25 million people. A few cases in the U.S. even today Morphology of a Flea: Morphology of a Flea Adults are tan to dark brown in color. Contain numerous bristles and spines. Mouthparts are modified for sucking blood. 3 pairs of legs are designed for jumping. At posterior end is the _____________________________ used to detect air currents and ________________ from potential hosts. Fleas are ____________________________________________________ (allows them to move easily through hairs of their hosts). Morphology of a Flea: Morphology of a Flea Females have an elongate abdomen containing a ___________________________ for storage of sperm after copulation. Males have a shorter abdomen containing an elaborate copulatory apparatus with spring-like ___________________________ - the largest of any animal in relation to body size! Life Cycle of the Flea: Life Cycle of the Flea Life cycle involves _____________________metamorphosis. 1. Eggs deposited in hair of host which drop off host in nest area. 2. ____________________ ______________________ and feed on debris in the nest. Life Cycle of the Flea: Life Cycle of the Flea 3. After 9-15 days, the larva forms a cocoon and becomes a ______________________ Pupal stage may last a few days to a year depending upon environmental conditions. 4. ___________________ emerges from pupal cocoon and awaits the presence of a host - jumps on host when available. Species of Fleas: Species of Fleas 2000 species of fleas have been described. Most are ectoparasites of ___________________________ (only about 100 species occur on birds). _____________________________ mammals are most common hosts of fleas; mammals with no permanent habitations have few fleas. Fleas have preferred hosts but will bite almost any mammal if the opportunity arises; commonly move from one host to another. Fleas to examine in lab: Fleas to examine in lab Don’t write these down – we’ll look at each one individually: Common names are associated with preferred hosts. Pulex irritans - ________________________________ Echidnophaga gallinacea - _____________________________ Ctenocephalides canis - __________________________ Ctenocephalides felis - ___________________________ Diamanus montanus - _________________________________ Identification of Fleas: Identification of Fleas Species of fleas are distinquished by the presence or absence rows of spines on the head and/or thorax. - ________________________________occurs on the head - ________________________________occurs on the thorax Pulex irritans: Pulex irritans Human flea – identified by __________________________________ ________________________________________________________ Adults will bite many other mammals as well as humans. Pulex irritans: Pulex irritans Echidnophaga gallinacea: Echidnophaga gallinacea Sticktight flea of Chickens. Will bite other mammals including humans. ID by _________________________ ______________________________ ______________________________ Attaches with mouthparts for long periods of time causing severe ulcerations of the skin of chickens Ctenocephalides canis and Ctenocephalides felis: Ctenocephalides canis and Ctenocephalides felis Dog and cat fleas. Recognized by presence of _________________________ _________________________ Both species will bite dogs and cats and vice versa. Humans are commonly bitten when newly emerged adults are looking for a dog or cat and will jump onto a human. Ctenocephalides canis and Ctenocephalides felis: Ctenocephalides canis and Ctenocephalides felis C. canis is identified by first spine of genal comb being about ½ length of second spine C. felis is identified by first spine of genal comb being about ¾ length of second spine Species identification is based on comparison of lengths of 1st and 2nd spines of ___________________________________ Diamanus montanus: Diamanus montanus Ground squirrel flea. Recognized by presence of _______________________ _______________________ Although preferring ground squirrels, they will jump onto humans from ground squirrels that are dead or dying from _______________________ Importance of Fleas: Importance of Fleas 1. Most fleas are occasional biters - bites cause little damage to skin and cause only minor itching. There are two exceptions: - the sticktight flea Echidnophaga gallinacea of chickens attaches permanently to chicken skin causing ulcerations in skin - the female chigoe flea Tunga penetrans penetrates human skin and causes____________________________ _________________________________ Tunga occurs in ____________________ __________________________________ (not in U.S.) Importance of Fleas: Importance of Fleas Cat and dog fleas serve as intermediate hosts of tapeworms -__________________________________________________________________________________________________ 3. Many species serve as vector of _______________________ Biology of Plague: Biology of Plague Plague is caused by __________________________________________________ (old name – Pasteurella pestis). Biology of Plague: Biology of Plague Plague is primarily a disease of _________________________________ - 2 cycles: ______________________________involves rats & fleas ________________________________involves ground squirrels & fleas Humans are infected with plague when ___________________________________ __________________________________________________________________ Infected fleas leave rat or ground squirrel host and bite the new human host. Biology of Plague: Biology of Plague Fleas are effective vectors as the bacteria multiply rapidly within the flea's digestive tract. Eventually the stomach fills with bacteria that block it. To clear this blockage, the flea will attempt to take a blood meal and will regurgitate its meal back and forth until the obstruction is cleared. Thus, a large number of bacteria are inoculated into the bite wound as the flea attempts to clear these bacteria. 3 Forms of Plague: 3 Forms of Plague 1. ____________________________ - most common form - characterized by swollen lymph nodes in the groin or axillary region - called a _________________ - other symptoms are headache, fever, prostration, and delirium - fatal in 25-50% of cases 3 Forms of Plague: 3 Forms of Plague 2. _____________________________________ - bacteria invade the circulatory system - source of bacteria for new flea vectors 3. _____________________________________ - bacteria occur in lungs - this form is highly contagious by droplet spray - flea vector is no longer needed to transmit this form These are 100% fatal if not treated. Why does plague kill?: Why does plague kill? Bacteria cause pathology by releasing a _________________________________which acts on _________________________________of cells Electron transport system is destroyed ATP production ceases Hemorrhaging occurs through the body. Vectors of Plague: Vectors of Plague Pulex, Ctenocephalides, Diamanus, and several species of rat fleas are vectors. In the U.S. one of these is most important – which one? Plague in World: Plague in World Pandemic of plague in the 1500's in Europe and spread throughout the civilized world - associated with ____________________________________ Plague in World: Plague in World Plague is still present in the world today - most associated with ______________________________________ Plague in World: Plague in World We have been averaging about 12 cases of plague/year in U.S. (except for major outbreak in 1981) Plague in the U.S.: Plague in the U.S. Plague in the U.S. only in the ____________________________ - almost every case is associated with dead or dying rodents Treatment of Plague: Treatment of Plague TREATMENT OF PLAGUE - _________________________________ are effective; treatment must be done over a long time to be sure that the bacterial toxin is eliminated slowly A ___________________________ is also available as a preventative. Flea Control: Flea Control CONTROL OF FLEAS - use of insecticides - use on pets and sleeping areas. 1. Spray sleeping area with _____________________________ - kills larvae and pupae. 2. ____________________________ utilize slow release vapors - somewhat effective. 3. ____________________________® - oral pill taken by dog or cat. Drug enters bloodstream and when ingested by flea disrupts egg development. Flea Control: Flea Control 4. ________________________®, _______________________®, and ___________________________® - topical insecticides that are placed on pet’s skin; drug wicks through skin and is ingested during flea bite. Kills fleas when ingested. Some also say they kill ticks and mosquitoes (to prevent _______________________________) ORDER DIPTERA – fliesChapter 38 : ORDER DIPTERA – flies Chapter 38 Flies are the most important group of vectors of diseases. A few are actually parasites themselves. We’ll look at them a group at a time. Mosquitoes: Mosquitoes Vectors of ____________________ - _____________________mosquitoes Vectors of filariasis (____________________________) - many species Vectors of _____________________ ______________________________- _____________________mosquitoes Vectors of ____________________ (arthropod borne viruses) - viruses that utilize an arthropod in its transmission Arboviruses vectored by Mosquitoes: Arboviruses vectored by Mosquitoes 1. ______________________________________- occurs in Central and South America and tropical Africa Vector is ______________________________- determined by Walter Reed in 1900 Disease is characterized by high fever, jaundice, and internal hemorrhaging (20% mortality). Arboviruses vectored by Mosquitoes: Arboviruses vectored by Mosquitoes Yellow fever virus cont: Normal hosts are __________________________________ No treatment but vaccine available Mosquito control is important in preventing this disease (shown by ____________________________________ in Panama) human Arboviruses vectored by Mosquitoes: Arboviruses vectored by Mosquitoes 2. Encephalitis viruses Many viruses which invade the CNS - disease is characterized by high fever and headaches. Slide64: a. Venezuelan Equine Encephalitis Occurs in horses and humans in South America; a few cases have been reported in Florida. Many species of _______________________ mosquitoes and _______________________blackflies are vectors of this disease Virus normally cycles through ________________________________ causing no pathology. Virus causes high mortality in horses (65%) but little mortality in humans (1%). humans horses Slide65: Eastern Equine Encephalitis Virus primarily cycles between ______________________ and ______________________mosquitoes Disease occurs primarily along the Atlantic Seaboard. If infected mosquitoes bite horses or humans, severe encephalitis results. Deadly! Mortality rate in horses is 90% and in humans (primarily children) is 30%. children horses Slide66: c. Western Equine Encephalitis ___________________________________ mosquito maintenance cycle. Disease occurs west of the Mississippi River Infection results in a mild CNS disease and is rarely fatal in horses and children (adults are not affected). children horses Slide67: d. St. Louis Encephalitis Disease occurs in the Midwest _______________________________________________mosquito cycle Horses are not involved; disease affects only _________________________ - generally not fatal. Older humans Slide68: e. LaCrosse Encephalitis One of a group of related encephalitis viruses – all are referred to as the California Group Encephalitis Viruses Cycle: _________________________________________ Over 1000 human cases have been reported in the Midwest Virus primarily infects children under 14; symptoms are headache, mental confusion, and nervous system damage. 2 deaths in children in Wisconsin Children Slide69: f. West Nile Encephalitis First identified in New York in 1999 - 62 human cases resulted in 7 deaths Number US cases in 2002: ______________________________________ Slide70: f. West Nile Encephalitis Life Cycle involves: ___________________________________________ Slide71: f. West Nile Encephalitis Reported on 2001 in birds in Milwaukee area Human cases reported throughout state in 2002 Numbers - __________________________________________________ Slide72: f. West Nile Encephalitis Humans at greatest risk are ________________________________________________________________________ Horses are also affected. Virus enters the CNS and causes inflammation of the meninges around the brain and the spinal cord. Symptoms include headache, high fever, neck stiffness, disorientation, tremors, and muscle weakness. Other Dipterans as Vectors: Other Dipterans as Vectors Deerflies (Chrysops) - vector of _________________________ Tsetse flies (Glossina) - vector of African Sleeping sickness caused by ____________________________________ Sandflies (Phlebotomus & Lutzomyia) - vectors of _______________________________________ Blackflies (Simulium) - vectors of ________________________________________& VEE Houseflies (Musca domestica) - phoresis of bacteria and protozoan cysts from feces Dipterans as Parasites: Dipterans as Parasites Infection of vertebrates by fly larvae (maggots) is called ___________________________________ 1. __________________________________________________ Adults are greenish-blue flies which deposit eggs in livestock or human skin wounds and larvae will live in the skin. Dipterans as Parasites: Dipterans as Parasites 2. _____________________________ - Gasterophilus intestinalis Adult bot flies lay eggs on hairs which are ingested by licking horses Larvae live in the horse's stomach and feed on blood - cause considerable damage to stomach mucosa of the horse. Dipterans as Parasites: Dipterans as Parasites 3. _______________________________ - 2 species of Hypoderma Adult heel flies bite legs of cattle and lay eggs in the wound. Larvae hatch and migrate to the lumbar region where they live beneath the skin. Larvae cut a breathing hole in the hide causing economic loss - hides are worthless.