寄生虫医学课件：arthropodmosquito fly flea scab mite(m)

1、MEDICAL ARTHROPOD INTRODUCTION,ARTHROPOD,Medical arthropodology: A science that study the morphology, taxonomy, life cycle, zoology, geographic distribution of medical arthropoda, and the relationship of medical arthropods with the transmission of the disease, as well as the measures for medical art

2、hropods control.,Medical arthropod: These arthropods related to human health.,Features,1) Segmentation and Bilateral symmetry 2）Chitinous exoskeleton 3）Growth by molting 4）The body cavity is a hemocoele and the circulatory system is open.,molting,Complete metamorphosis(holometabola) (including egg,

3、larva, pupa and adult),Incomplete metamorphosis(hemimetabola) ( including egg, larva/nymph, adult).,Metamorphosis,Classification,Insecta: mosquito, fly, sandfly, flea, louse, cockroach, etc. Arachnida: tick, mite, spider, etc. Crustacea: crab, shrimp, etc. Chilopoda: centipede. Diplopoda: millipede.

4、,Insecta,Arachnida,Crustacea,Chilopoda,Diplopoda,Harm for human health,Direct harms 1) Sucking blood and annoyance (harassment ),2) Envenomization,Envenomization is the introduction of a poison into the body of humans and animals. e.g. Biting from toxic spiders.,Child with hypersensitivity to mosqui

5、to bites. Mosquito bites can produce a severe allergic reaction.,3)Allergic reaction,4)Invading tissue.,Demodex spp,Indirect harms: Disease transmission Arbo-diseases is the disease transmitted by arthropods,1)Mechanical transmission Among those diseases that may be transmitted in a mechanical manne

6、r,The bacterial enteritis. Enteric organisms may be carried by flies that feed on fecal material to foods destined for human consumption.,2)Biological transmission Arthropod as a vector,Some infectious organisms require an arthropod host for completion of their life cycle. Most arthropod-borne disea

7、ses are carried in this fashion,Arthropods and Arbo-diseases,1) It is closed relationship with human 2) The arthropod is a common species 3) The life span of the arthropod is long enough,Biological evidences,Determination of vector arthropods,Epidemiological evidences: the seasonal fluctuation is co

8、nsistent with the epidemic trend of the suspected diseases,Laboratory evidences,Natural infection evidences,Control,Environmental management,Physical measures,Chemical measures,Biological measures,Genetic measures,Insecticide: 1) Organochlorine e.g., DDT (dichlorodiphenyltrichlorethane) 2) Organopho

9、sphates e.g., malathion, fenitrothion etc 3) Carbamates e.g., malathion, fenitrothion etc 4) Pyrethrum: allethrin( for mosquito-repellent,incense), permethrin,deltamathrin,Chemical measures,MOSQUITO,Morphology Adults of mosquitoes are generally 1.6 to 12.6mm long, consists of the head, thorax, and a

10、bdomen.,head,thorax,abdomen,antennae,compound eyes,palp,Mouthparts (proboscis),With mandibles,Without mandibles,Structure of proboscis,Some recognition features of Anopheles, Culex and Aedes,Anopheles,Culex,Aedes,Anopheles,egg,Culex,Aedes,boat-shaped, have a pair of lateral floats, laid single and f

11、loat on the water surface.,.,cylindrical or ovoid in shape and no float. They are laid stuck together in “eggs rafts”,.,olive-shaped, no float. They are laid single on humid soil or the bottom of water (cans, contains),The larave of anopheles,Float hair,Breathing pore,The larave of culex,呼吸管毛,Siphon

12、 tube for breathing,Hair of breathing tube,The larvae of Aedes,Recognition features in the adults of Anopheles, Culex and Aedes,Anopheles,Culex,Aedes,Adults,Dark-gray,Brown,Black,Wings,Anopheles with white and black spots,Culex and Aedes without white and black spots,The life cycle of mosquito,The c

13、omplete life cycle contains eggs, larva, pupa and adult. All mosquitoes require water for the development of the larvae and pupae, but the adults live in land.,Ecology,1) Breeding habits,Breeding sites: the place where the females lay eggs and breed larvae,Slowly flowing water type 缓流型,Jungle type 丛

14、林型,Dirt water type 污水型,Container type 容器型,Paddy field type 田塘型,There are five type of breeding sites,Paddy field type of breeding- sites includes rice fields, marsh and pond, in which water is large, water clean and still. The breeding sites is suitable for Anopheles sinensis, anopheles anthrophagus

15、, and culex triaeniorhynchus etc.,Slowly flowing water type includes stream and irrigation raceway with clean and slowly flow water, which is the breeding site of Anopheles minimus commonly.,Jungle type includes mountain stream, stone cave and spring pond, in which Anipheles dirus is found usually.,

16、Dirt water type includes dirt water pit, sewer,sullage, fecal pit, which are the breeding sites of Culex pipiens pallens, C.p. quinquefasciatus.,Container type includes water vats, jars, bamboo container, tree-hole etc, which are the breeding sites of Aedes albopictus and A. aegypti.,2) Mating,group

17、 dancing,3) Host preference,Prefer to bite human. A. anthropophagus, Culex pipiens pallens. Prefer to bite animal . A. sinensis Both.,4) Gonotrophic cycle,A cycle from blood-meal to egg-laying,5) Resting sites of the adults,Domestic roosting. A. minimus, Culex pipiens pallens. Semi-domestic roosting

18、. A. sinensis Wild roosting . A. dirus,6) Seasonal fluctuation,The phenomenon that population density of the mosquito varies with season is called seasonal fluctuation.,Mosquito and diseases,1) Direct harm to humans,Biting by mosquitoes can cause irritation, or allergic reaction,2) Transmission of d

19、iseases,7) hibernation,In the winter, mosquitoes dont suck blood and hide in warn place such as inside of house; the ovary dont develop . The average month temperature is over 10, there is no hibernation for mosquitoes.,Malaria,Control,1) Larva control,2) Adult control,Chemical control, e.g., insect

20、icide is placed in the water; biological control, e.g., predators, disease agents; source reduction or habitat management.,Insecticides (direct action and residual action); Personal protection.,FLY,Fly belong to Order Diptera, there are more than 1500 species.,The fly measure 5-10 mm long and are du

21、st-gray or black color.,Morphology,1) Head: a pair of compound eyes and three single eyes, a pair of antenna; the mouthparts is lapping type or sponging type, a few species have sucking type mouthparts.,2) Thorax: the thorax bears three pairs of legs and a pair of wings. 3) Abdomen:,Each leg termina

22、te has a pair of claws and a pair of pupvilli. These specific structures can carry the pathogens.,The life cycle of the fly,It belongs to complete metamorphosis, the development stages contains eggs, larvae, pupae and adults.,Ecology,A feces B garbage C putrid plants D decaying flesh,1 Breeding plac

23、es,the species with lapping mouthparts. They have dirt habits of feeding indiscriminately on both excreta and foods, and excreting and regurgitation their partially digested meals over food.,2 Feeding,A Omnivorous (杂食性),B blood-sucking the adult fly with piercing-mouthparts,Flies and diseases,1) Mec

24、hanical transmission: intestinal dysentery, e.g. cholera, typhoid fever, bacterial dysentery, amebic dysentery etc. 2) Biological transmission: trypanosomiasis is transmitted by flies.,myiasis,3)Myiasis: the disease caused by the parasitism of fly larva, cutaneous myiasis, intestinal myiasis, urogen

25、itel myiasis and eye myiasis.,.,The main methods of control are as follows: 1) Source reduction by environmental modify 2)Insecticide use.,Control,3) Physical methods: in house, barns, milking parlors, screening to keep flies out is the first line of defense,Common flies,Fleas belong to Order Siphon

26、aptera, are ecto-parasites of mammalian and birds. There are more than 2000 species in the world. among them, only a few species are vectors of zoonosis.,FLEA,The males measure 3 mm long, and females are shorter than the males. The body is brown-yellow color and covered with bristle.,Morphology,The

27、life cycle of the flea.,Fleas can cause harms to humans by irritation, parasitism and transmission of diseases. Fleas frequently bite person on the ankles and legs, but at night a sleeping person may be bitted on other parts of the body.,Harm to humans,The most serious disease-plague is transmitted

28、by flea. The pathogen of plague is Yersinia pestis. Flea-born epidemic typhus is also important disease transmitted by fleas. The fleas are also intermediate host of Dipylidium caninum and Hymenplepi diminuta.,The structures related to transmitting plague,plague,Control,The main methods of control a

29、re as follows: a) environmental modify b) insecticide use c) personal protection,TROMBICULID MITE,Trombiculid mite, which common name is chigger, red bug, or harvest mite, belongs to Family Trombiculidae. Among the common genera in this family is Leptotrombidium deliensis in China.,Morphology,Keys f

30、or identifying chiggers are based on the larvae. They are typically reddish or orange, tiny mites 0.2 to 0.5 mm long.,the larva of Leptotrombidium deliensis,The body consists of gnathosoma and idiosoma. The gnathosoma have a pair of pedipalpies and cheliceraes. The idiosoma have three pairs of legs

31、and a dorsal scutum with a lot of hairs and a scutum. A scutum with five scutal setaes and a pair of sensillae locates in the upper part of the dorsal scutum. There are two pairs of ocellies beside scutum,Life cycle,Nymphochrysalis,prelarva,imagochrysalis,Ecology,The parasitic stage have a low host

32、specificity. They feed on small mammals such as rat, and birds etc. sometime it feed on humans. Chiggers remain at the surface of the skin of host to feed. In China, the common species of the mite is Leptotrombidium deliensis,Harm to humans,1 chigger dermatitis or trombidiosis(恙螨皮炎). 2 tsutsugamushi

33、 disease(恙虫病). R. tsutsugamushi or Orientia tsutsugamushi, which pathogen can be transmitted into filial generation of the mite by egg.,SCAB MITE,The Astigmata (无气门亚目)includes both parasitic and free-living mites. Scab mite, Sarcoptes scabiei parasitize on humans and mammalian.,Morphology,Microscopi

34、c view of Sarcoptes scabiei,Dorsum and venter of The Scab mite,male,female,The female are 0.3-0.5mm long by 0.25-0.4mm wide,the male are 0.2-0.3mm long by 0.15-0.2mm wide,The life cycle of Scab mite,The female mite selecta places on the body where the skin is thin and wrinkled, between fingers, wris

35、ts, elbows, feet, penis, scrotum, buttocks and axillae.,Pathogenesis,The mite can cause more severe skin reactions, such as itching and allergic reactions. The irritation and hypersensitivity seen to result from excretions, which the female deposit in the skin as they burrow and oviposit. Secondary

36、bacterial infections may also occur, probably as a result of scratching.,Childs arm exhibiting papular rash due to Sarcoptes scabiei,Scabies lesions are caused by Sarcoptes scabei burrowing under the skin. A typical location is on the hands, particularly the webbing between the fingers, as shown in

37、this image.,Cross sectional view of the burrows created in the epithelium by Sarcoptes scabei.,Transmitting way,Directly or indirectly contact with patient,Diagnosis,Determining whether a person has been invaded by the mites is based on the following clinical signs and symptoms finding the mites in

38、the skin. Sinuous tracks in the skin, inflammation, itching are all indicators of scab mites. Later in the infection, crusty patches are seen. The crux of the matter is finding the mites in the skin, but it is necessary to scrape the skin somewhat nevertheless.,Scraping examined under a compound mic

39、roscope for mites, parts of mites, eggs and fecal pellets.,The transmission of the disease is accomplished by direct contact with the infected person or with their clothing or bedding. For scabies control, the acaricides can be applied to skin after a hot, soapy bath. All clothing and bedding should

40、 also be laundered. The acaricides include 10% Brimstone ointment (硫磺软膏)etc,Prevention and Control,DEMODICIDAE MITE,Demodicidae mite belong to Family Demodecidae. Demodex spp are all parasites of mammals. They cause a disease usually called demodectic mange or demodecosis.,Demodex spp. Are elongate

41、and have four pairs of stubby legs. The mouthparts are not apparent and the hysterosoma (末体)is quite long.,Morphology,Adult of D. folliculorum,Adult of D. brevis,D. brevis,D. folliculorum,Life cycle,The pattern of development is as follows: egg larva protonymp nymph- adult.,They cause a disease usua

42、lly called demodectic mange or demodecosis. Members of the genus have a high degree of both host and sit specificity. Human have two species, D. folliculorum, which lives in hair follicles, and D. brevis, which is found in sebaceous glands.,The presence of the mite can be determined by gently squeez

43、ing the skin and looking for the mite in the exudates. They are seen mostly on the face in oily areas, such as around the nose, or in the eyebrows and eyelashes which may be plucked and examined under a microscope.,Diagnosis and control,The acaricides include 10% Brimstone ointment etc.,Lice are permanent ectoparasite. The parasitic lice of humans include 3 species: Pediculus humanuss(head louse) P. humannus corporis( body louse) Pthirus pubis(crab louse, p