Parasitology Lecture 4 PDF

  Inecta Animalia Arthropoda  Arachnida  Crustacia  Insects  Three body regions (head, thorax, and abdomen), 6 legs and us...

  Inecta Animalia Arthropoda  Arachnida  Crustacia  Insects  Three body regions (head, thorax, and abdomen), 6 legs and usually 2 pair wings on thorax, 1 pair of antennae.  Crayfish,  Have 10 to 14 legs, 2 body regions (cephalothorax and  Sowbugs, abdomen) and 2 pair of antennae.  Fairy Shrimp  Spiders,  Have 8 legs, no antennae, 2 body regions  Ticks, Mites, (cephalothorax and abdomen)  Scorpions CLASSIFICATION: MEDICAL IMPORTANCE OF ARTHROPODS: ① Dermatitis by the insect bite:  e.g., lice, mosquitoes. ② Inoculation of poisons:  e.g., ticks & scorpion ③ Tissue invasion:  Sarcoptes scabiei (Scabies)  Larvae of flies (myiasis). ④ Entomophobia:  Abnormal fear when seeing arthropod (Spiders). For transmission of diseases agents, by: ① Mechanical transmission (Passive carrier)  Direct by inoculation.  Indirect by contamination. ② Biological transmission (Part of its Life cycle).  The fertilized female needs a blood meal for egg development so only female transmits diseases to man.  Life cycle (2 weeks) aquatic immature stages, terrestrial adult.  EGGS: are laid on the surface of any collection of water, hatch after 2-3 days at suitable temperature (25˚c), and larvae come out.  LARVAE: feed on organic matter suspended or floating in water, molts to give pupa.  PUPA: capable of breathing in water but doesn't feed molts to adult. ① Human malaria ③ Yellow fever ② Lymphatic filariasis ④ Dengue fever ①  Elimination of breeding places (water collection).  Removal of plants where larvae breed.  Natural enemies such as frogs (eats both aquatic & adult stages) fish (Gambusia affinis) and insects as Dragon flies. ②  Mosquito nets (27 meshes/square inch),  Wire screening of doors and windows.  natural enemies as spiders, frogs  Mosquito repellants: citronella oil, indalon  Insecticides:  Pyrethrium: cuticle poison.  Residual insecticides: DDT and gammaxane.  [Egg →Larva → Pupa → Adult]. Both male & female transmits infections ① Annoyance. ② Mechanical transmission of Viruses, Bacterial & Parasites disease (helminths eggs, protozoa cyst). ③ Accidental myiasis. ① Health education and sanitation ② Physical and mechanical control:  Elimination of breeding places.  Fly net having a mesh size of 2–3 squares/cm  Ultraviolet light-traps ③ Insecticides: D.D.T. to kill larvae and adults  Small insect 2-4 mm  Wingless  3 pairs of legs. ① Pediculus humanus capitis (head louse). ② Pediculus humanus corporis (body louse). ③ Phthirus pubis (pubic louse). [Egg → Nymph →Adult]. ① MEDICAL IMPORTANCE (PEDICULUS HUMANUS):  Pediculus humanus: Obligatory, permanent ectoparasites.  Head Lice are not known to transmit pathogens. Nuisance but not a health hazard. A) PEDICULOSIS (VAGABOND’S DISEASE):  Both types lead to this syndrome.  Manifests by dermatitis, skin becomes thickened  Shows spots of hyperpigmentation, due to prolonged exposure to salivary secretion. B) VECTOR OF DISEASES: (BODY LOUSE ONLY):  Epidemic typhus.  Epidemic relapsing fever.  Trench fever. ② MEDICAL IMPORTANCE FOR PUBIC LOUSE (PTHIRUS PUBIS):  Habitat: adult lives on pubic hairs, axilla, beard, moustache, eyebrows eyelashes  Transmission: by contact with infested individuals during sexual intercourse, or less commonly by clothes  Not transmit any disease  Irritation of the skin, which show bluish patches ① CONTROL (PEDICULUS HUMANUS)  Body lice Frequent bathing and boiling clothes Using insecticides (DDT) in 10 dust for inner surface of clothes  Head lice ① Malathion (Methyl bromide) 1 or 1 Lindane ointment or spray are effective against nits ② Licid, Nix, RID as a spray (synthetic pyrethrin ③ Iverzine lotion (ivermectin , anti nematode medication). ② CONTROL FOR PUBIC LOUSE (PTHIRUS PUBIS):  Delousing by proper bathing, and treatment of clothes by laundering, dry heat and dusting with powder containing 5 10 DDT or gamaxane  Boil underwear and clothes  Shave axillary and pubic hairs  Removal of Phthirus pubis from eyelashes by forceps (+ and application of yellow oxide of mercury ointment  Avoid contact with infected persons or using their clothes ① Small, bilaterally compressed. ② Brown in colour, with no wings. ③ Formed of head, thorax and abdomen. ④ Mouth is adapted for piercing and sucking of blood. ⑤ Life cycle (Egg → Larva → Pupa → Adult). ① Plague: Acute severe infectious disease. Fleas act as vector and transmit it to human e.g., Pulex irritans (Human flea), Xenopsylla cheopis (Rat flea). ② Endemic typhus fever. Fleas act as vector and transmit it to human. ③ Flea dermatitis: Itching due to biting followed by 2ry bacterial infection. ① The adult and the larval stages are sprayed with insecticides. ② Infected dogs and cats are treated by 1 or 4% rotenone. ③ Floors, carpets and other domestic articles in which fleas may breed should be sprayed with kerosene. CLASSIFICATION: ① Ticks (hard & soft). ② Mites (Sacoptes scabeii, Demodex folliculorum, HDM). ③ Scorpions. LIFE CYCLE :  Egg→ larva→ nymph→ adult.  The body is one mass sac like.  Mouth is adapted for piercing and sucking of blood.  The adult and nymph have 4 pairs of legs while the larva has 3 pairs.  Ticks are classified into 2 families: ① Ixodidae (hard ticks). ② Argasidae (soft ticks). ① It causes Dermatitis. ② It causes Tick paralysis: Produced by some toxins in the saliva of tick. The toxin produces a blockage of the neuro-muscular junctions and probably some of the synapses of the spinal cord. Paralysis disappears after removal of the causative tick. ③ Diseases transmitted by ticks: Rocky Mountain spotted fever, Lyme disease. Viral meningoencephalitis fever. Texas cattle fever (Babesia)  Depends mainly on spraying insecticides on the floors, in cracks in the walls and places where ticks are exposed to hide.  By the removal of tick, it is best to anaesthetize the tick with ether or to suffocate it with gasoline oil, glycerin or kerosene. ① Cosmopolitan. ② Small mite, grey in colour, oval in shape. ③ One mass (cephalothorax and abdomen). ④ Mouth is adapted for tearing the tissues.  It lives in intracutaneous tunnels between fingers, toes, ulnar surface of the arm, elbows, axillae, groin, breast, umbilicus, shoulder, back and buttocks.  The head and neck are not affected.  The female adheres to the skin then burrows tortuous tunnels in the epidermis and deposits eggs.  The larvae hatch from eggs, move freely over the skin and change into nymph, both larvae and nymph are found in hair follicles. By contact with infected person or by using his internal clothes. Scabies is called “seven years itching”.  Itching ↑↑ during night. It is activated by warmth of affected part.  Mites produce tortuous tunnels, dark in color due to toxins secreted and their excretions.  Severe itching resulting in scratching and secondary bacterial infection, resulting in vesicles and pustules.  Crusted Scabies (Norwegian Scabies):  Severe form of infestation can occur in immunosuppressed.  High numbers of mites are present in keratotic lesions on the body and extremities, highly infective. ① Clinically:  By the severe itching during night, its sites distribution in the skin, and by finding the scratches, vesicles and pustules. ② Laboratory:  Skin scrapping of tunnels or lesions and then rapid microscopic examination of the specimen. ① Application of scabiecidal as:  Lindane 1%  Pyrethrum cream 5%  Sulphur- lanoline suspension 5-10%  Benzyl benzoate emulsion or cream (25%) ② Ivermectin:  Single oral dose or more  Recently as a topical application. ① Treatment of infested patients. ② Boiling of internal cloths and bed linen. ③ Personal hygiene as frequent bathing. ④ Avoid contact with infested patients.  ① Worldwide distribution. ② Very minute, and elongated. ③ Lives in the hair follicles and sebaceous glands particularly around the nose, eyelids, mouth and face. By direct contact with patient or by using the polluted towels.  Causes acne, black heads, dermatitis and blepharitis.  Squeeze out contents of black head or sebaceous gland and examine under the microscope for the adult and its stages.  Sulphur ointment 15% or Benzyl benzoate 25%.  Oral ivermectin.  Found in dust on floors, furniture, mattresses and beds.  They produce dust allergens that produce allergic reactions in humans.  They cause allergic rhinitis, conjunctivitis and bronchial asthma.  Exclusion of dust from bedrooms and furniture of sensitive individuals.  Thorough cleaning beds and furniture using a vacuum cleaner.  Scorpions when attack man, inject the poison in his body.  In children the injected dose is fatal. Death occurs due to cardiac and respiratory failure. ① A tourniquet is applied proximal to the site of sting to prevent dissemination. ② The wound is incised and sucked. ③ Potassium permanganate is put on the wound to oxidize the venom. ④ Antitoxin (Antivenom).  Spraying insecticides to kill them, e.g. 10% D.D.T. and 0.2% pyrethrum in kerosene.