Parasitology Lecture 5 PDF

 The infection of a fly larva (maggot) in human tissues.  Flies may deposit their eggs or larvae on human food  Larvae may enter through urinary or genital orifices or on anus (particularly in children in rural areas) or through lesions on orifices during urination in during sleep or...

 The infection of a fly larva (maggot) in human tissues.  Flies may deposit their eggs or larvae on human food  Larvae may enter through urinary or genital orifices or on anus (particularly in children in rural areas) or through lesions on orifices during urination in during sleep or defecation in open places. open places.  Larvae find their way to the intestine and cause non-  Cause obstruction to urine flow with dysuria or specific symptoms as nausea, vomiting, abdominal inflammation in the urinary passage with pus, mucus discomfort or pain with diarrhea. and blood in urine.  Living and dead larvae appear in stools or vomitus  Larvae are passed in urine.  larvae of Calliphora  Musca  Fannia (latrine fly)  Calliphora  Lucilia  Fannia.  Musca  Sarcophaga  Occurs when wounds or ulcers are invaded by larvae  Larvae of some flies are attracted to the discharge of the flies or healthy skin. coming from eye, or the nose, to find their way to  Larvae may invade intact skin causing boil like lesion. the conjunctiva or the nose and may reach the brain  Severe pain in the eye is the first complaint in ocular  These larvae may cause serious damage. myiasis followed with lacrimation and conjunctival irritation.  Wohlfahrtia, Chrysomia, Cordylobia (WC).  Larvae of Calliphora , Sarcophaga (CS)  Dermatobia and Hypoderma  Osesterus.  Purulent exudates discharged from running ears attract some flies and they lay eggs or larvae there.  Larvae invade middle ear, inner ear or the brain tissue in extreme cases.  Wohlfahrtia, Sarcophaga, Lucilia and Chrysomia.  Larvae invade only living tissues  Includes flies which habitually oviposit  When fly eggs or larvae are deposited (Obligatory tissue parasite) or larviposit on dead tissues of man or on food material (cheese and animals. vegetables) and then they are  Hypoderma and Dermatobi larvae :  Attracted by offensive discharge accidentally ingested leading to  Invade skin → boil like swellings. coming from neglected wounds, or intestinal myiasis. inflamed ears and eyes and thus  When eggs are deposited around anal  Oestrus larvae: deposit their larvae or eggs in such canal or urogenital orifice → larvae ① In eye: conjunctivitis and corneal tissues. can travel up passages → intestinal or ulcers.  The presence of larvae prevent healing urogenital myiasis, respectively. ② In nose: obstruction & persistent and induce sepsis.  Examples: bloody purulent discharge.  Examples:  Piophila in cheese ③ In ears: external otitis.  Sarcophaga, Lucilia, Calliphora.  Drosophila in fruits and Fannia  Wohlfahrtia and Chrysomia. (latrine fly).  Intentional introduction of Piophila casei larvae into pecorino cheese produces the famous, but illegally-produced, Italian cheese known as "casu marzu,"  A delicacy desired for the famous pungent taste left behind when the larvae digest and ferment the cheese. Individuals eat goo-like paste as well as the living maggots. ① Clinical picture according to the tissue invaded. ② By finding the larvae in the lesion. ③ Identifying the larvae species by its posterior spiracles. ④ Breeding living larvae to adult stage to be easily identified. ① Removal of the larvae: excision or endoscopy. ② Treatment of secondary infection: by antiseptics and antibiotics. ① Insecticides and nets to control flies. ② Protection of food from flies. ③ Cleaning and covering wounds with gauze and wound dressing. ① Which fly usually deposit their larvae at the urinary or genital orifices? a) Hypoderma b) Oestrus c) Fannia d) Gasterophilus ② A 22-year-old male presented to surgery clinic with open wound with offensive discharge, with examination, few larvae were found, this is a case of : a) accidental cutaneous myiasis b) semi-specific cutaneous myiasis c) specific cutaneous myiasis d) Internal myiasis