Entomology part 3 by Dr. Sookun Rajeev K

Ticks, Mites, Lice & Cyclops

1. MEDICAL ENTOMOLOGY Part 3 Dr. Sookun Rajee v K M.D Dept. Of Community Medicine

2. TICKS

3. The Ticks Are small Arachnids. They have no antennae. 3 pairs of legs in larval stage and 4 pairs of legs in adult stage. They are external parasites living suck blood of mammals, birds and sometimes reptiles and amphibians. The 2 families of medical importance are Ixodidae (Hard Ticks) and Argasidae (Soft Ticks). The Hard Ticks remain attached to the host while Soft Ticks leave the host after feeding.

4. Identifications Features Hard Ticks ( Ixodidae ) Soft Ticks ( Argasidae ) Scutum (Dorsal Shield) Capitulum (Mouth Parts) Nymphal Stages Adult Feeding time Female blood meals Egg laying events Total egg laid Present Anterior, Visible from above One Several days One One 3000 - 8000 Not Present Ventral, Not visible from above Several 30 – 60 mins Several Several 400 - 500

5. Hard Tick Male Female

6. Soft Tick Abdominal wall is smooth Dorsal surface has small dot like mamillary tubrercles Small, soft and leathery cuticula , Mouthparts invisible from dorsal aspect The scutum /dorsal schield is `absent

7. Hard Tick and Soft Tick

8. Diseases Transmitted Lyme disease Q Fever Colorado Tick Fever Rocky Mountain Spotted Fever African Bite Fever Crimean Congo Hemorrhagic Fever Tularemia Tick-Borne Relapsing Fever Babesiosis Tick-Borne Meningoencephalitis

9. Control Measures Dimethyl phthalate (DMP) is a good tick repellant, especially against larvae. Clothes dipped in 5 percent DMP and 2 percent soap solution retain the repellant effect for one to two months. Infested animals may be dusted with lindane , malathion or DDT.

10. Itch Mite ( Sarcoptes Scabiei )

11. Identifications Tiny (0.1-0.3 mm) endo -parasitic mite Lives in epidermal layer of skin Body - Capitulum & Abdomen Eyes, antennae & wings are absent 2 pairs of legs in front 2 pairs behind.Front legs end in long tubular process-suckers Hind legs end in long filamentous bristles In females 4 th pair end in suckers

12. The Itch Mite Causes human scabies Scabies is characterized by an intensely pruritic, erythematous, papular eruption caused by burrowing of adult female mites in upper layers of the epidermis, creating serpiginous burrows. Itching is most intense at night Sites of lesion – hands & wrist (63%),extensor aspect of wrist (11%),

13. Preferred sites interdegital , popliteal fold and groin

14. Diseases Transmitted Scabies

15. The Itch Mite

16. Control Measures Avoid direct contact with the infested person. Proper personal hygiene should be observed including bath with soap and water. The infested persons and contacts should be treated thoroughly with 3 – 5 % sulfur ointment or 20 - 25 % benzyl benzoate emulsion. The patient should take hot bath with soap and water, scrub the affected parts with brush, dry the body with rough towel, and rub the medicine all over, especially over the affected parts. He should then put on clean clothes and take no bath for 48 hours. The old clothes should be sterilised by boiling. Second application may be necessary. 5% tetmosol solution is a good sarcopticide and can be applied tds . 0.5 to 1 % BHC or Gamma HCH ( lindane ) in coconut oil is a good sarcopticide when applied on the affected part bd or tds at interval of two to three days.

17. LICE

18. The Lice These are blood sucking insects with a dorsoventrally flattened body and clawed legs. Both sexes live on the host itself. Gray in color and 2 to 3 mm long. They can live for a week without feeding. Head and body lice look alike and interbreed . The head is conical, joined with the thorax by a constriction . It bears a blood sucking proboscis and two antennae . The head louse is darker, smaller and brisker than the body louse . The crab louse is 1 to 2 mm long and has a squarish shape. It has a blunt, truncated head and strong legs, hence the name. It is found in pubic and perineal hair. Louse bites cause irritation and sometimes, urticaria . Prolonged infestation may result in deep pigmented skin or melanoderma .

19. Identifications The following three species infest man: 1. Pediculus capitis (Head louse) 2. Pediculus corporis (Body louse) 3. Phthirus pubis (Crab or pubic louse). Habitats correspond to their names. Lice infestation of any part of the body is known as PEDICULOSIS Body of louse is divided into 3 parts: Head: bears a pair of antennae,each with 5 segments. Thorax : 3 pairs of legs attached ventrally. Abdomen: elongated and consists of 9 segments

20. Louse

21. Diseases Transmitted P. corporis and P. capitis transmit Rickettsia prowazeki , the causative agent of epidemic typhus, and quintana , the causative agent of trench fever. The crab louse is not known to transmit any disease. The head and body lice also transmit Borrelia recurrentis which causes relapsing fever. The organisms enter the body when infected louse is crushed on the skin. Dermatitis may occur due to scratching and secondary infection.

22. Control Measures Prevention of Infection: • Avoid contact with infested person. Hat , cap, comb, hair brush and clothes of an infested person should not be used. The bedlinen and under garments should be properly washed and the hair combed as a part of personal hygiene. If necessary, clothing may be dusted with carbaryl powder in highly lousy surroundings.

23. ) Delousing Measures: Applying 2 percent DDT emulsion or dusting with 10 percent DDT. 0.2 percent lindane in coconut oil should preferably be used. 0.5 percent malathion lotion (1% in case of body louse) is effective. The lotion should be allowed to act for 12 to 24 hours before the hair is washed. Carbaryl dust may also be used as louse powder. An emulsion designated NBIN (68 percent benzyl benzoate, 6 percent DDT, 12 percent benzocaine and 14 percent Tween-80) applied after 1:5 dilution in water is also effective against lice as well as nits. Leather, wool and silk may be deloused by soaking them in 2 percent cresol and 50 percent soap emulsion for one hour.

24. CYCLOPS

25. The Cyclops Class- crustacea Up to 1-2 mm in size. Also known as water flea. They live in fresh water. The head and thorax are fused to form a bulbous cephalothorax. Abdominal portion is narrowed. They have 2 pairs of antennae and Single small pigmented eye. In females 1 st abd . segment has a pair of ovisac

26. Identifications Male Abdomen consists of lower segment and ends as caudal fork Female External ovisac with eggs is present attached to abdominal segment.

27. Diseases Transmitted Intermediate host of Guinea worm or Dracunculiasis Disease is transmitted when human drink contaminated water infected with cyclops . Intermediate host of Fish tapeworm or Diphyllobothrium .

28. Control Measures Cyclops can be controlled by Physical, Chemical, Biological and Engineering methods Physical : Straining of water through a piece of fine cloth is sufficient to remove cyclops . Boiling water at 60 o C kills cyclops . 2) Chemical: Chlorine destroys guineaworm larvae and cyclops . 3) Biological: Small fishes like Barbel and Gambusia feed on cyclops . 4) Engineering: Provision of drinking water through piping water supply, use of tubewells . Abolition of stepwells .

29. THANK YOU