Medical entomology

by- Dr. Avinash Banjare
Dr. Dharmaraj Nag

1. MEDICAL ENTOMOLOGY Definition Study of arthropods of medical importance

2. Direct contact – directly transferred from man to man through close contact eg . Scabies & pediculosis Machenical transmission- transmitted mechanically by vectors eg – diarrhoea, dysentry etc Biological transmission- disease agent undergoes developemental changes with or without multiplication in vectors

3. 3 types of biological transmission Propagative only multiplication NO cyclical change eg –plague bacilli in rat flea Cyclo -developmental only cyclical changes NO multiplication eg - Filarial parasite in culex mosquito, Cyclo-propagative BOTH multiplication n cyclical changes eg - malarial parasite in anopheles mosquito

4. MOSQUITO 4 imp groups of mosquito in India Anopheles Culex Aedes Mansonia

5. Body consists of 3 parts HEAD- i . A pair of large compound eyes ii. A long proboscis with which mosquito bites iii. A pair of palpi on either sides of proboscis iv. A pair of antennae [ male-bushy . Female – less bushy] B. THORAX - i . A pair of wings dorsaly ii. Three pairs of legs ventrally C . ABDOMEN- ten segments [last 2 modified to form external genitalia]

6. LIFE HISTORY

7. ANOPHELES Species An. culicifacies (cause RURAL MALARIA) An. fluviatilis (found in F OREST & FRINGES) An. stephensi (cause URBAN MALARIA ) An.dirus (found in North east states) An. m inimus etc Diseases- malaria filaria [outside India] Sits at 45 degree FRESH WATER breeding

8. CULEX ( nuisance mosquito) species - Culex fatigans ( C.quinquefaciatus ) Diseases- . Bancroftian filariasis . JE . Westnile fever Rapid urbanization and industrialization without adequate drainage are responsible for its spread Breeds in dirty water collection Flight range – 11kms HUNCHBACK appearance

9. AEDES White stripes on black body – so also known as Tiger mosquito. Species . Aedes aegypti . Aedes vittatus . Aedes albopictus Diseases Dengue DHF Yellow fever Filariasis outside India

10. Abundant during rainy season breeds in artificial accumulation of water eg . Tin ,broken bottles etc Lays eggs singly CIGAR shaped Bites during day time Flight range 100meter Aedes aegypti INDEX- % House showing showing breeding of Aedes larva - upto 400m area around port - should be less than 1%

11. FEEDING HABIT female – Heamatophagous ( require blood meal) male – plant juice (never bite) TIME OF BITING mostly evening or early part of night RESTING HABIT rest during day in dark and cool corners BREEDING HABIT Anopheles –clean water Culex - dirty polluted water Aedes - artificial water collection Mansonia - water containing aquatic vegetaion

12. HIBERNATION Adult mosquito hibernate in unfavourable conditions like extreme winter DISPERSAL Generally do not fly far from breeding place EXCEPT Culex ( up to 11kms) LIFE SPAN varies from 8 to 34 days influence by temperature and humidity males are short lived

13. MOSQUITO CONTROL MEASURES ANTI LARVAL MEASURES a. Environmental control b. Chemical control c. Biological control ANTI-ADULT MEASURES a. Residual sprays b. Space sprays c. Genetic control PROTECTION AGAINST MOSQUITO BITES a. Mosquito nets b. screening c. Repellents

14. ANTI LARVAL MEASURES A- ENVIROMENTAL CONTROL most important step – to eliminate breeding places ( source reduction ) Source reduction comprises minor engineering methods such as filling, levelling and drainage of breeding places and water management. B- CHEMICAL CONTROL commonly used larvicides a. Mineral oil b. Paris green c. Synthetic insecticides

15. Mineral oils When applied on water oil spreads and forms a thin film which cuts off the air supply to the mosquito larvae and pupae. eg mosquito larvicidal oil, fuel oil,diesel oil etc. Paris green - Chemical composition- copper acetoarsenite . - Acts as stomach poison. - Mainly kills anopheles larvae because they are surface feeders . Synthetic insecticides -examples of most effective organophosphorous larvicides Fenthion Chlorpyrifos Abate

16. C- BIOLOGICAL CONTROL -some fish feed readily on mosquito larvae. Eg.Gambusia affinis Lebister reticulatus

17. ANTI ADULT MEASURES A- RESIDUAL SPRAYS -Eg .DDT [most commonly used] Malathion Propoxur Lindane B- SPACE SPRAYS -Sprayed as mist or fog -Pyrethrum Extract: Pyrethrin (active principle) -it acts as nerve poison C- GENETIC CONTROL -Sterile male technique - Cytoplasmic incompatibility -chromosomal translocations -sex distortion etc

18. PROTECTION AGAINST MOSQUITO BITES A- MOSQUITO NETS >size- 0.0475 inch diameter >no of holes in one square inch -150 B- SCREENING >Screening of the building is done with copper and bronze gauge. >costly but excellent results . C-REPELLENTS > Eg.Diethyltoluamide (DEET)-most common Dimethyl carbate Indalone >short duration of protection

19. HOUSE FLIES Important species : Musca domestica -most common M. vicinia M.nebulo etc General characters Mouse grey in colour Body divided into Head Thorax Abdomen HEAD : A pair of antennae A pair of large compound eyes(male-close together;female -set apart widely) A retractile proboscis(sucking liquid foods)

20. THORAX : Marked with 2-4 dark longitudinal stripes which is characteristic of genus musca A pair of wings 3 pairs of legs covered with numerous short and stiff hairs known as Tenent Hairs ABDOMEN :segmented and shows light and dark markings

21. LIFE HISTORY EGG : The female lays from about 120-150 eggs at one sitting in moist decaying organic matter LARVA :Also known as Maggot .They are white segmented and footless with a narrow anterior end and broad posterior end. PUPA : dark brown and barrel shaped ADULT :Life span upto 15-25 days

22. BREEDING HABITS : -Fresh horse manure -Human excreta -Manure of other animals etc FEEDING HABITS : -can NOT eat solid foods.it vomits on solid food to make a solution of it and sucks in a liquid state. RESTLESSNESS : -help in spread of infection mechanically.

23. RESTING HABIT : -Rest on vertical surfaces and hanging objects. DISPERSAL : -Normally remain close to breeding places but they disperse frequently upto 4 miles.

24. TRANSMISSION OF DISEASE : Disease transmitted Typhoid and Paratyphoid fevers Diarrhoeas and dysentry Cholera Gastroenteritis etc.. MODE OF TRANSMISSION : Mechanical transmission Vomit drop Defecation

25. CONTROL MEASURES ENVIRONMENTAL CONTROL Storing garbage & kitchen waste in bins with tight lids Provision of sanitary latrines Stopping open air defecation etc 2. INSECTICIDAL CONTROL Residual sprays- DDT,lindane,malathion,fenthion etc Space sprays- pyrethrin , DDT,HCH Larvicide - diazinon,dimethoate

26. 3.FLY PAPERS - contains resin and castor oil - applied to the stripes of wire and hung up in places where flies abound 4.PROTECTION AGAINST FLIES - screening of house, hospitals, food markets etc 5.HEALTH EDUCATION -Health education regarding disease transmission and fly awareness

27. SAND FLY BODY HEAD Bears a pair of long, slender and hairy antennae; palpi and a proboscis. B. THORAX Bears a pair of wings and 3 pairs of legs. Wings are densely hairy and legs are very long out of proportion of body. C ABDOMEN Has 10 segments. Covered by hairs.

28. DISTINGUISHING FEATURES FROM MOSQUITO Size : Smaller than mosquito. Wings: Wings upright and lanceolate in shape. Bifurcated vessels on wings. Legs: Longer as compared to size of body. Hairs : Hairy insect. Hopping : Hops about an dont fly by choice.

29. HABITS Only female bites during nights. Bite is irritating & painful. Dark place holes, crevices in wall, trees etc.. DISEASE TRANSMITTED SPECIES DISEASE TRANSMITTED Phlebotomus argentipes Kala- azar Phlebotomus papatasii Sandfly fevers Oriental sore Phlebotomus sergenti Oriental sore S. punjabensis Sandfly fever

30. CONTROL OF SANDFLY INSECTICIDES – Spraying with DDT & Lindane . SANITATION- Removal of shrubs and vegetation. Filling u of cracks and crevices in walls and floors.

31. TSETSE FLY Only found in African continent. Attack generally during travelling. Causes- Sleeping sickness/ trypanosomiasis LIFE CYCLES : 1.Larva 2.pupa 3.Adult

32. CONTROL MEASURES INSECTICIDES : DDT,Dieldrin CLEARING OF VEGETATION DESTRUTION OF WILD ANIMALS GENETIC CONTROL: Sterile male tech.

33. BLACK FLY Vectors of Onchocerciasis in Africa,Mexico,Central and South America. Size too small but wings are comparatively large. Life cycle: 1.Egg 2.Larva 3.pupa 4.Adult

34. CONTROL MEASURES Abate :Acts as Larvicidal Adult: Uncontrollable due to high flying speed.

35. LICE TYPES Head louse ( Pediculus capitis ) Body louse ( Pediculus corporis ) Pubic or crab louse ( Phthirus pubis) HEAD AND BODY LOUSE IDENTIFICATION FEATURES Body is dorsoventraly flattened Body - Head Thorax Abdomen Thorax- Square shaped Elongated abdomen- 9 segments Last segment – (Female- Bilobed Male- Pointed)

36. LIFE CYCLE Egg (Nit) Nymph Adult DISEASE CAUSATIVE AGENT 1.Epidemic typhus Rickettssia prowazeki 2.Relapsing fever Borrelia recurrentis 3.Trench fever R quintana 4. Dermatitis due to scraching and seconadry infection

37. CRAB LOUSE IDENTIFICATION FEATURES Dorsoventrally flattened body Square shaped body Large legs Large claws to hold onto hair strand Appears as a crab Cause no disease

38. CONTROL MEASURES INSECTICIDAL CONTROL 0.5% MALATHION lotion PERSONAL HYGIENE Daily bathing Freq hair wash No sharing of combs etc

39. FLEAS

40. RAT FLEA IDENTIFICATION FEATURES Bilaterally compressed body Body covered with bristles Body head Thorax Abdomen Head bears piercing mouth parts Thorax – 3 pairs of strong legs

41. Life cycle Egg Larva Pupa Adult Habits Both male female suck blood Cant fly hops only

42. Disease transmitted Bubonic plague Endemic typhus Chiggerosis CONTROL MEASURES INSECTICIDES - DDT dust Diazinon spray Malathion spray REPELLENT Diethyl toluamide Rodent control

43. TICK TYPES Hard tick ( ixodidae ) Soft tick ( argasidae ) Identification features of HARD TICK Oval body No clear distinction of body 4 pairs of leg NO antennae Covered with scutum Head visible from above

44. MITE TROMBICULID MITE Spider like arthropod Vectors of scrub typhus in asia and south pacific LI FE CYCLE Egg Larva Nymph Adult

45. CONTROL MEASURE TICKS & T. MITE INSECTICIDAL CONTROL DDT, malathion , lindane etc ENV CONTROL Cracks and cervices are filled up PROTECTION OF WORKERS Protective clothing with repellents

46. ITCH MITE Globular body. No demarcation into cephalothorax or abdomen. Four pairs of legs- Two front pairs bear suckers Two back pairs are long slender LIFE CYCLE Egg Larva Nymph Adult

47. Causes SCABIES ; first disease of mankind with known cause. Scabies leads to dermatitis due to secondary infections. PARTS AFFECTED Hands and wrist Extensor aspects of elbows Axillae Buttocks Lower abdomen etc

48. CONTROL MEASURES All the family members must be treated simultaneously. Before application of Sarcopticides thorough scrub with soap and hot water. Sarcopticides used- 1.Benzyl benzoate 2.Gamma HCH 3.Tetmosol solution 4.Sulphur ointment

49. INSECTICIDES Substances which are used to kill insects. PESTICIDE is general term includes insecticide, fungicide herbicide, rodenticide etc. CLASSIFICATION : 3 groups Contact poison : kill insect primarily by contact Eg . Pyrethrum, DDT,HCH, dieldrin etc.. 2. Stomach poison : when ingested cause death of insect Eg . Paris green ,sodium fluoride 3 . Fumigants : give off vapours which have lethal effect on insects Eg . Sulphur di oxide

50. DDT Dichloro diphenyl trichloro ethane Synthesised by ZIEDLER PROPERTIES : White amorphous powder with mild unpleasant smell. Insoluble in water but dissolve in organic solvent. Most active fraction of DDT : para para isomer . ACTION : Contact poison acts on nervous system of insects . Permeates into insect through cuticle causing paralysis of wings and legs , convulsion n finally death. Take several hours to kill.

51. APPLICATION : As a residual spray. Doses: 100-200 mg/sq foot area As a dust: 5-10 % for control of lice,tick,fleas . DISADVANTAGE : Adverse effect on certain wild animal but the benefits far outweigh the hazards so it is most widely used insecticide.

52. HCH/BHC Hexa chloro cyclohexane Benzene hexa chloride Gammexane Michael faraday PROPERTIES : White or chocolaty colour with musty odour . Irritating to eye nose skin. Most active constituent: Gamma isomer. Pure HCH containing 99% gamma isomer is called LINDANE OR GAMMA-HCH .

53. ACTION : Contact poison Residual action is shorter than DDT. APPLICATION : Same as DDT. Dose : 25-50mg/sq feet

54. MALATHION Least toxic among all OP compounds. Yellow or clear brown liquid with unpleasant smell. Used as water dispersible powder. 100-200 mg/sq foot ABATE(TEMEPHOS) OP compound ;brown viscous liquid soluble in petroleum solvent. Due to its less toxicity used for the control of Anopheles in domestic wells.

55. DIAZINON Liquid volatile product kills as CONTACT poison and as fumigants Effective against DDT resistant insects. 60-100 mg/sq foot

56. FENTHION Brown liquid with garlic smell . Insoluble in water As effective as DDT As residual sprays with dose 100 mg/sq foot Highly effective against culex .

57. PROPOXUR New carbamate insecticide. Effective against anopheles which are resistant to DDT and dieldrin .

58. PYRETHRUM Insecticide of vegetable origin extracted from flowers of Chrysanthemum 4 active principle; PYRETHRINS 1 and 2 Cinerins 1 and 2 These all are NERVE poisons The ready to spray solution contains 0.1% prethrin . Highly effective against adult mosquitoes. Disadvantage: Does NOT possess residual action.

59. Synthetic pyrethroids Replaced the natural pyrethrins 10 times more effective. Eg . Resethrin,proparthin MINERAL OILS Oils like kerosene,crude oil extensively used to kill mosquito larvae and pupae. Oil suffocate and poison the aquatic stages of mosquito.

60. PARIS GREEN Copper aceto arsenite . Green micro crystalline powder soluble in ammonia and concentrated acids. Contains more than 50% arsenious oxide Stomach poison used against anopheles larvae.

61. RODENTICIDE 2 types Single dose/acute : lethal to thr rat after single dose. Multiple dose cumulative : require multiple feeding . ACUTE/SINGLE : Barium carbonate : white tasteless powder mixed with wheat or rice flour. Takes 2-24 hr to kill. Zinc phosphide : more efficient rodenticide . Mixed with rice and wheat flour. 3hr to kill. Because of its good safety record,low cost and high effectiveness used widely.

62. MULTI DOSE : Warfarine Slow death 4-10 days Fumigation : Effective method of killing both rats and rat fleas Eg calcium cyanide( cyano gas ), carbon di sulphide sulphur di oxide etc .. Cyano gas is extensively used in India for fumigation of rat burrows. Cyano gas powder gives off hydrogen and cyanide which is lethal to rat and rat fleas.