[MICRO] Parasitic Skin Infections.pdf

MICROBIOLOGY AND PARASITOLOGY 09/05/2024. MOD 5: PARASITIC SKIN INFECTIONS Dr. Gen...

MICROBIOLOGY AND PARASITOLOGY 09/05/2024. MOD 5: PARASITIC SKIN INFECTIONS Dr. Genevee M. Banta Trans Group/s: 9A I. SAMPLE CASE ○ Species: Sarcoptes scabei Patient X is a 39 year old male who came to the clinic due to severe itchiness of his lower extremities. It started 4-5 B. HEAD AND BODY LOUSE INFESTATION months ago and it is accompanied by papular skin lesions Etiologic agent: Pediculus sp, (lice) on the lower extremities. On physical examination, he Transmission: skin-to-skin contact or fomites observed pigmented skin lesions with disseminated These parasites lay eggs that usually attach at the hair hypopigmented areas. follicles. Lice infestations may also cause secondary bacterial II. EPIDERMAL PARASITIC SKIN INFECTIONS infection. Parasitic skin diseases that mainly affect the ○ Occurs when constant scratching damages skin epidermis include etiologic agents like: allowing bacteria to enter ○ Ectoparasites (e.g., scabies and pediculosis) ○ Pediculus species can also act as vectors for some ○ Hookworms or nematodes: causes cutaneous bacteria larva migrans which present as thin and elongated skin lesions with snake-like appearances III. ECTOPARASITES Parasites that depend and live outside the host’s body. ○ Sarcoptes scabiei (itch mite) and lice accomplish their life cycles and growth on the stratum corneum or on the upper layer of the epidermis. These are transmitted via skin-to-skin contact or fomites. They survive by taking “blood meals” from their hosts. Most ectoparasite skin infections present with itchiness. Lice and its eggs (nits) as seen in a patient’s hair A. SCABIES Etiologic agent: Sarcoptes scabiei (itch mite) Taxonomic classifications of Pediculus species: Transmission: skin-to-skin contact or fomites ○ Kingdom: Animalia Presentation: pruritic, hyperkeratotic, crusted, ○ Class: Insecta scaling, fissured plaques in interdigital spaces, ○ Order: Phthiraptera elbows, axilla, groin, breasts, umbilicus and buttocks ○ Family: Pediculidae ○ Severe itchiness is commonly observed during the ○ Species: night. Pediculus capitis – head louse ○ Maculopapular skin lesions usually appear in the Pediculus humanus – body louse interdigital areas or moist areas. ○ As female ectoparasites lay their eggs at night, it C. PUBIC LOUSE INFESTATION causes irritation on the skin and manifests with Etiologic agent: Phthirus pubis (pubic “crab” louse) itchiness. Transmission: sexual contact, close contact, fomites Taxonomic classifications of Phthirus pubis: ○ Kingdom: Animalia ○ Phylum: Arthropoda ○ Class: Insecta ○ Order: Phthiraptera ○ Suborder: Anuplura ○ Family: Pthiridae IV. CESTODES (TAPEWORM) A. NODULES (CYSTICERCOSIS) Etiologic agent: larval form (cysticercus) of Taenia solium known as Cysticercus cellulosae Maculopapular skin lesions as seen in patients with Scabies Presentation: cystic nodules in the muscle or subcutaneous tissue Taxonomic classifications of S. scabiei: ○ Kingdom: Animalia ○ Phylum: Arthropoda ○ Class: Arachnida ○ Order: Acarina ○ Family: Sarcoptidae Microbio and Para - Mod 5 Parasitic Skin Infections 1 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  1. ANIMAL HOOKWORMS May infect humans or animals Produces linear tracts after the percutaneous entry of the parasite Transmission: skin penetration of filariform larva from contaminated soil with animal excreta 1.1 Cutaneous Larva Migrans Other terms: Creeping eruption, ground itch, sandworms, plumber’s itch Etiologic agent: filariform larvae of animal hookworms, Ancylostoma braziliense and Ancylostoma caninum Nodules caused by C. cellulosae seen in a patient’s back ○ Human infection occurs with NONhuman species of nematodes. 1. CYSTICERCUS CELLULOSAE (TAENIA SOLIUM) ○ Since they are identified as animal hookworms, Transmission: ingestion of T. solium egg from humans are only considered as accidental hosts. contaminated soil, water, and food (fecal-oral route) ○ Parasite does not complete the life cycle within This larval form can migrate and encyst in different humans organ tissues (skin, muscle, kidney, heart, liver) even in Presentation: Serpiginous, slightly elevated, the brain, a condition known as neurocysticercosis. erythematous tunnels in the epidermis with ○ Presentation of the brain infection depends on the inflammation along the migration of filariform larvae number and location of cysticerci and the presence ○ 1-2 cm migration rate per day of inflammation around the encysted larvae. ○ Skin lesions may disappear spontaneously NEUROCYSTICERCOSIS SERPIGINOUS SKIN LESION FORMATION Seizures 1 Humans who walk barefooted are commonly Hydrocephalus infected by these animal hookworms. CLINICAL Signs of increased intracranial 2 Linear tracts are produced and the surrounding PRESENTATION pressure such as headache, nausea, tissues are edematous and inflamed vomiting, dizziness, ataxia, confusion 3 As the hookworm migrates, the previous tract dries and scars, and is accompanied by severe itchiness History of exposure on the site. Clinical presentation DIAGNOSIS Detection of cystic lesions or nodular Combination of the ff: calcifications in neuroimaging Antibody detection in serologic testing In neuroimaging, cystic lesions (sometimes with characteristic scolex) and nodular calcifications can be found. The cysticerci in the brain are round and measure 5-20mm in diameter. Risk factors (according to CDC): consume/eat food that is prepared by a person who is infected with pork tapeworm, living in one household with someone who has pork tapeworm and those who have pork tapeworm. 1. TAENIASIS (TAENIA SOLIUM) Patient with serpiginous skin lesions Transmission: a person gets infected by eating raw or undercooked pork containing the cysticerci larvae. 2. GNATHOSTOMA SPINIGERUM These cysticerci then develop into adult worms in the human intestine whereIntestinal symptoms are Transmission: ingestion of an infected fish, reptile, observed. chicken, or pig containing L3 in its meat Has the ability to move and migrate outside its usual location. V. NEMATODES (ROUNDWORM) Moves in the subcutaneous layer May also cause skin infections Serpiginous skin lesions caused by this is known as Its presentation and transmission may vary depending larva migrans on the parasite Other associated skin lesions: ○ Panniculitis: inflammation of subcutaneous fat A. SERPIGINOUS SKIN LESION layer of the skin due to the movement of the Recognized due to its movement in the skin parasite Possible causative agents: ○ Pseudofurunculosis: similar to furuncle that allows ○ Hookworms parasitic epidermal elimination ○ Strongyloides stercoralis ○ Gnathostoma spinigerum 2.1 Larva Migrans The serpiginous skin lesions caused by these causative Etiologic agent: Gnathostoma spinigerum agents differ in terms of rate of movement and the layer A serpiginous subcutaneous lesion of the skin that they penetrate. Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 2 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  Appears with migratory swelling due to the migrating ○ Hydrocele is detected when the light (from the pen third stage larvae (L3) of G. spinigerum light) passes through a fluid-filled scrotum. 3. STRONGYLOIDES STERCORALIS Transmission: skin penetration of filariform larva Also produces linear tracts after the percutaneous entry of the parasite This reaches (penetrates) the dermis layer and has the fastest movement in the skin. Larva currens of S. stercoralis are observed in chronic strongyloidiasis Those with prolonged infection may present with recurrent serpiginous urticarial rash. Strongyloides moves 10 cm per hour, and this is faster Patient with hydrocele than the few centimeters movement per day of a hookworm. D. CALABAR SWELLING Etiologic agent: Loa loa 3.1 Larva Currens Disease: Loiasis Serpiginous erythematous, pruritic dermal plaques Transmission: bite of Chrysops/deer fly/red flies that is caused by Strongyloides stercoralis (vector) (Strongyloidiasis) Inflammation of the upper extremities, commonly on Sudden onset of appearance is observed and its the hands, and sometimes with joint involvement. movement may progress as fast as 10cm/hour ○ Localized subcutaneous swelling with itchiness ○ Racing larva: 5 cm or more migration rate per day that predominates on the extremities. or as fast 10cm per hour with intermittent movement It is secondary to hypersensitivity reaction to Loa Loa. The pruritic, erythematous lesion may disappear within If a worm is isolated from the eyes, the patient is most 12-18 hours when it migrates to the intestinal mucosa likely diagnosed with loiasis. via the bloodstream. The next subtopics (B-D) are transmitted by a vector bite. Lymphatic filariasis may present with lymphedema or hydrocele. ○ The parasites causing this skin penetration is transmitted through the bite of a female Anopheles mosquito. On the other hand, Loa loa is transmitted by Chrysops spp. Patient with loiasis B. LYMPHEDEMA E. LEOPARD’S SKIN, HANGING GROIN, AND Etiologic agent: Wuchereria bancrofti ONCHOCERCOMA Disease: Lymphatic filariasis Etiologic agent: Onchocerca volvulus Known to be an enlargement of the lower extremities Disease: Onchocerciasis/River blindness that can be unilateral or bilateral Transmission: bite of black flies or Buffalo gnat Elephantiasis (vector) ○ Gross enlargement of limbs, breasts and genitalia that occurs in chronic infection PRESENTATION OF ONCHOCERCIASIS ○ Body’s response to the mature or dying adult worms in the lymph tissues Discoloration or depigmentation with Leopard’s early skin aging of the shins; Skin hypopigmented areas is due to the absence of melanin Wrinkling of upper thighs and buttocks; Hanging Groin microfilariae in the interstitial fluids of the skin Firm, nontender, round nodules within the subcutaneous tissue and is commonly Oncho- cercoma found on the trunk, hips or limbs (bony prominences); contains adult worm within the nodules Severe papular dermatitis with darkening Patient with lymphedema of the skin on one limb (commonly a leg); Sowda due to formation of autoantibodies and C. HYDROCELE hyperimmune response to the parasite Etiologic agent: Brugia spp. (B. malayi and B. timori) Disease: Lymphatic filariasis Observed in light to moderate infection Transillumination procedure: fluid is observed Itchy Rash while heavy infections (up to 200 million within the scrotum when a pen light is placed under it. microfilariae) may lead to severe outcomes. Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 3 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  Presentation: A cercarial dermatitis; petechial Heavy infection is due to continued hemorrhages with edema and pruritus (itchy rash) exposure for many years that occurs within an hour after cercaria enters into the body through skin penetration. COMPLICATION (if left untreated) ○ Then, maculopapular rashes appear which may progress into vesicular lesions. Parasite may reach the eyes; accumulation ○ Also followed by headache, chills, fever, diarrhea Bilateral of microfilariae in the cornea, anterior and and eosinophilia (known as snail fever or blindness posterior chambers, retina, sclera and optic Katayama fever) 2-12 weeks after exposure nerve. Hence, its other name. The skin lesions are due to the hypersensitivity reaction (allergic response) to the dead cercariae in the subcutaneous tissues of the skin. Leopard’s skin and Hang groin, respectively Patient with swimmer’s itch VII. BLOOD FLAGELLATES (PROTOZOANS) Blood flagellates that cause skin infections are: ○ Trypanosoma spp. ○ Leishmania spp. A. TRYPANOSOMA BRUCEI Disease: African sleeping sickness Vector: Tsetse fly Mainly causes: Onchocercoma 1. WINTERBOTTOM SIGN F. TRICHINELLOSIS Enlargement of the lymph nodes (lymphadenopathy) Aside from skin penetration and vector bite, a skin that is soft, rubbery and nontender commonly seen in infection can also be secondary to ingestion of the cervical or neck area undercooked meat. ○ Prominent in Gambian Trypanosomiasis, caused Etiologic agent: Trichinella spiralis by Trypanosoma brucei gambiense Transmission: Parasitic skin infection secondary to ingestion of undercooked meat with encysted larvae Presentation: Muscle and joint pains when the parasite embeds into the muscle ○ Others: muscle weakness, periorbital edema, facial edema, diarrhea ○ Muscles affected: extraocular muscles, deltoid, biceps, gastrocnemius or pectoralis muscles Winterbottom Sign Patient with muscle swelling and pain 2. TRYPANOSOMAL CHANCRE Metacyclic trypomastigotes of T. brucei are introduced VI. TREMATODES (FLUKEWORM) through the bite of the tsetse fly and multiply at the site of inoculation to cause induration and swelling, which A. SWIMMER’S ITCH may progress to trypanosomal chancre. Other terms: clam digger’s itch or sawah itch Etiologic agents: Schistosoma spp. [S. mansoni B. TRYPANOSOMA CRUZI (common) and S. japonicum] Disease: Chagas disease/American sleeping Transmission: skin penetration after contact with sickness water infested with infectious cercariae. Vector: Kissing bug/reduviid bug ○ It burrows into exposed skin Mainly causes: Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 4 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  ○ Lesions appear and may cause erosion in the 1. CHAGOMA nasopharyngeal or palatine mucosal surfaces. Presentation: subcutaneous inflammatory nodule at the site of T. cruzi entry VIII. FACTORS CONTRIBUTING TO SKIN INFECTIONS According to WHO, several factors have contributed to 2. ROMANA’S SIGN the development of skin infections caused by parasites. Presentation: unilateral painless (bipalpebral) Poor communities are more at risk mainly due to poor swelling of the eyes hygiene and inability to seek medical help. ○ A characteristic onset for T. cruzi, esp. in children ○ The kissing/reduviid bug bit the patient on the eyelid FACTORS CONTRIBUTING TO SKIN INFECTIONS which resulted in its inflammation. 1 Crowded environment 2 Poor hygiene 3 Insufficient access to healthcare and/or treatment 4 Malnutrition 5 Sharing of personal equipment/materials IX. CASE STUDY Given a 39-year old male patient who presented with The Romana’s Sign severe itchiness, hyperpigmented, and hypopigmented skin lesions on the lower extremities: C. LEISHMANIASIS SPP. 1 What is the most probable diagnosis? Disease: Cutaneous, mucocutaneous, visceral leishmaniasis Onchocerciasis Vector: Sand fly Mainly causes: 2 What do you call the pigmented lesions presented by this patient? 1. LEISHMANIASIS RECIDIVANS Etiologic agent: Leishmania tropica Leopard’s skin Presentation: Scaly, erythematous papules and nodules appear years after the healing of primary skin In order to confirm the diagnosis, laboratory tests should lesions be requested. ○ New skin lesions are observed when the previous infection is not completely or properly treated. X. SUMMARY I.e., ineffective treatment or do not readily The blood flagellates and some nematodes are respond to treatment transmitted through a vector bite. Other nematodes that present with serpiginous skin lesions are transmitted through skin penetration. ○ Trematodes (Schistosoma spp.) are also capable of skin penetration Cestodes or Cysticercus cellulosae may manifest with nodules after ingesting the parasitic egg from contaminated food, water, and soil. Trichinella is a nematode, which invades the muscle and usually presents with muscle swelling. I. DIAGNOSIS OF ECTOPARASITES Leishmania Recidivans A. SCABIES 2. CUTANEOUS LEISHMANIASIS (ORIENTAL SORE) Detection: The eggs or fecal pellets and the Etiologic agents: L.tropica, L.major, L.mexicana, L. ectoparasites are detected by scraping the skin lesion braziliensis and placing it in a plastic box or petri dish. Presentation: infection penetrates the epidermis and Treatment: Permethrin 5% (drug of choice) applied causes ulceration and stays in the skin for 8-14 hours then wash with soap and water. 3. CHICLERO ULCER ○ Alternative meds: Ivermectin and Lindane Etiologic agent: L.mexicana Prevention: Linens and clothings should be washed ○ L. mexicana infection is typically confined to a thoroughly and placed under sunlight. single, indolent ulcerative lesion that heals in about 1 year, leaving a characteristic depressed B. HEAD AND BODY LOUSE INFESTATION circular scar Survival: Presentation: ear cartilage destruction ○ Head louse may survive for one month ○ Takes three weeks for the eggs to become adult 4. MUCOCUTANEOUS/MUCOSAL LEISHMANIASIS ectoparasites Presentation: Lesions are slow growing but extensive. Epidemiology: common in children ages 5-13 Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 5 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  Detection: Crawling lice and numerous nits/eggs are 3 When they reach the intestine, they mature and detected in active infestation produce eggs after mating. Treatment: Permethrin lotion 1%, Lindane shampoo Animal hookworms can only mature in the 1% (2nd line) intestines of animal hosts. ○ Other treatment: pyrethrins with piperonyl Eggs mix with the stool and are released into butoxide, Benzyl alcohol lotion 5%, Ivermectin the environment. lotion 0.5%, Malathion lotion 0.5%, Spinoda 0.9% topical suspension 4 In the environment, the egg hatches and transforms into rhabditiform larvae and into filariform larvae. C. PUBIC LOUSE INFESTATION Survival: May only survive in the environment for less 5 When humans get infected, this larvae remains in than 48 hours. the skin and no longer migrates or matures. Detection: Eggs are deposited on the hair shaft and appears as blue or grayish macules (maculae Since filariform larvae of animal hookworms are limited in ceruleae) the skin of humans, they can only be diagnosed by history and physical examination. II. DIAGNOSIS OF SERPIGINOUS SKIN LESIONS The approach and the diagnosis of serpiginous skin 2. Diagnosis and Treatment lesions may vary based on the history and Diagnosis: clinical history and physical examination characteristic of the skin lesion. Treatment: Ivermectin (DOC), albendazole, thiabendazole A. CUTANEOUS LARVA MIGRANS B. LARVA CURRENS 1. ANIMAL HOOKWORMS 1. STRONGYLOIDES STERCORALIS Hookworms penetrate the skin and create Manifestation: serpiginous tracts serpiginous-like skin lesions or tracts as it moves The filariform larvae of this parasite penetrate the skin across the epidermis then later gains access to the blood vessels and Since this skin lesion is only observed in the epidermal eventually migrates into the gastrointestinal tract. layer, it is known as cutaneous larva migrans, or also ○ (Skin → Blood Vessels → Gastrointestinal Tract)/ known as ground itch of hookworms. Autoinfection: a common way for a person to be It is NOT a common infection among humans. reinfected by strongyloides. Caused by animal hookworms ○ Occurs when a patient defecates and does not ○ Animal hookworms rarely cause infections to practice proper hygiene they may get reinfected humans, but if they do, they manifest as upon touching their anus and accidentally putting serpiginous skin lesions. their finger in their mouth. ○ Patients with cutaneous larva migrans are ○ Occurs when the newly hatched larvae never diagnosed based on clinical history and physical exit the host but, instead, undergo their molts examination, different from intestinal hookworm within the intestine infections. 1. Life Cycle of Hookworms Strongyloides stercoralis 1. Strongyloides stercoralis development DEVELOPMENTAL STAGES Egg → Adult Worm → 2 Larvae* (focus of discussion) Cutaneous Larva Migrans Rhabditiform larvae are identified based on the In the life cycle of hookworms that cause cutaneous presence of short buccal mucosa or cavity, muscular larva migrans: esophagus, and prominent genital primordium. ○ Definitive host: cats and dogs ○ The primordium has the immature sex cells of this parasite. LIFE CYCLE OF ANIMAL HOOKWORMS 2. Differences Between Hookworm and S. stercoralis 1 Hookworms enter the animal skin and are carried by the blood vessels to the heart and lungs. 2 Hookworm larvae are then coughed out or swallowed. Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 6 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  Life Cycle of Strongyloides Mouth Opening Difference between Hookworm and Strongyloides. The life cycle of Strongyloides stercoralis has the free-living and parasitic cycles. The hookworm and Strongyloides can be differentiated ○ In the free-living cycles, it just demonstrates the simply by looking at the mouth opening or buccal developmental changes of Strongyloides on the capsule. environment. ○ The mouth opening of hookworm’s rhabditiform ○ In the parasitic cycle, after penetrating the intact larvae is three times longer than that of skin of a human host, the filariform larvae migrate Strongyloides stercoralis. to the lungs through the bloodstream and These parasites also have filariform larvae that are lymphatics. It is either coughed up or swallowed. recovered through culture. Within the small intestines, it becomes adult female worms and reproduces through parthenogenesis. ○ Parthenogenesis in adult female filaria — do not need to mate with adult male worms to reproduce The eggs are formed and Rhabditiform larvae are subsequently produced. ○ This parasite can only produce ADULT FEMALE worms within the human host, but in the environment it matures into either an adult male or adult female worm. Among the parasites causing the serpiginous skin lesions, Strongyloides is the ONLY parasite that causes auto-infection. ○ Auto-infection is when this rhabditiform larva Tail Difference between Hookworm and Strongyloides. becomes filariform larvae, and it has the ability to migrate across the intestines and also the perianal Baermann and Harada-Mori are the concentration skin. techniques for this culture. Reinfection may even occur and in relation to larva ○ These methods are helpful in the detection of currens, those with recurrent serpiginous skin lesions Strongyloides stercoralis filariform larvae. are usually associated with chronic strongyloidiasis The filariform larvae of S. stercoralis is differentiated and repeated auto infection. from the hookworm by looking at the tail part. The stool of a patient with this manifestation should be ○ Under the microscope, the Strongyloides evaluated for the presence of filariform larvae. filariform larvae have a slit in the tail end, but the hookworm filariform larvae have a pointed tail. 4. Diagnosis Strongyloides can be detected using the agar plate Nutrient agar plate culture: specialized stool test; culture. This type of culture is considered as the most rhabditiform larvae forms a visible tracts over the agar sensitive method for larval recovery and identification. Culture tests: Harada-Mori test and Baermann test for ○ In agar plate culture, the stool is placed onto the larval detection agar plate where it is sealed and maintained for two Microscopy of duodenal aspirate: detect filariform days at room temperature. larvae if parasite is not detected in specialized stool test ○ The parasite produces visible tracts on the agar as it crawls and it may also carry bacteria as it 5. Treatment migrates in the plate; hence, the visible tracts are The skin manifestation may resolve spontaneously observed. when the parasite enters the bloodstream. For chronic infection: Ivermectin (DOC) or Albendazole 3. Life Cycle of Strongyloides stercoralis C. LARVA MIGRANS 1. GNATHOSTOMA SPINIGERUM Third stage larva of Gnathostoma spinigerum has four hooklets and openings on its cephalic or head part. Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 7 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.  ○ It has 4 rows of spines and 4 openings in the cephalic bulb and spines in its body. A. CYSTICERCOSIS A disease in which the cysticercus, the larval form of pork tapeworm or T. solium, settle within the subcutaneous area and multiple tissues and then manifest as nodules. The eggs of T. solium are ingested and then the oncospheres are released when the egg hatches. ○ These oncospheres are released to the tissues and organs then become cysticerci. ○ When it is already embedded in the muscle, it will NO longer mature into its adult form. The larvae hatch from the eggs, migrate and encyst as cysticerci in various tissues of pigs and humans. 3rd stage of Gnathostoma spinigerum 1. Life Cycle of Gnathostoma spinigerum Life Cycle of Taenia solium 1. DIAGNOSIS AND TREATMENT Most of the parasites causing skin infections are diagnosed through skin biopsy. ○ For the nodules containing cysticercus cellulosae, the hooklets and suckers are detected in the affected tissue as seen in these images. Diagnosis: biopsy — presence of scolex with hooklets and 2 pairs of suckers. Treatment: Praziquantel; surgical removal of the subcutaneous nodule Life Cycle of Gnathostoma spinigerum The larvae do not mature in a human host. After ingestion, it penetrates the intestinal wall and may cause vomiting, anorexia and epigastric pain. It migrates through tissues or subcutaneous layers where it causes migratory swellings, inflammation, redness and pain. The swelling may reappear in an area that is close to its first swelling and this is due to the body's allergic response to the parasite. 2. Diagnosis and Treatment Diagnosis: skin biopsy or removal of third stage larvae Treatment: Albendazole (DOC), Ivermectin; surgical removal of parasite Cysticercus cellulosae detected in affected tissue III. DIAGNOSIS OF NODULES IN TISSUES Aside from the parasites causing the serpiginous skin IV. BIOPSY OF PARASITIC SKIN INFECTIONS lesions, nodules or mass-like lesions may also be presented by other parasites, such as Taenia solium. Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 8 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. A. TRICHINELLOSIS Blood can also be used to detect the microfilaria of Encysted larvae are observed embedded in the Wuchereria bancrofti and Brugia malayi. affected muscle ○ Wuchereria bancrofti has larger and sweeping curves than Brugia spp. ○ The nuclei of Brugia malayi can be detected up to the terminal and subterminal end of its tail. ○ W. bancrofti has no nuclei in its tail end. Trichinella spiralis. Wuchereria bancrofti. 1. LIFE CYCLE OF TRICHINELLA SPIRALIS Main host: Pig Alternate host: Man Excystation or release of larvae during digestion Larvae penetrate the mucosal epithelium then matures Adult males and females mate and produce the motile larvae. ○ Adult female Trichinella releases approximately Brugia spp. 1,000 larvae. Larvae are carried by blood and lymph to striated Loa loa, W. bancrofti, and Brugia spp. have a coiled muscles and encyst within the muscle. tail and a covering to protect its nuclei and internal surfaces. 2. DIAGNOSIS AND TREATMENT Muscle biopsy: encysted larvae in the affected muscle, confirmed serologically Other tests: ○ Microscopy: blood sample; eosinophilia ○ Stool exam: adult worms or larvae ○ Radiological examination: calcified cysts are detected Treatment: Albendazole, Mebendazole B. SKIN SNIP BIOPSY Used in the detection of Onchocerca microfilaria in a patient with hanging groin and leopard skin. Microfilaria of Onchocerca volvulus has no covering unlike Loa loa, Wuchereria bancrofti, and Brugia spp. ○ Nuclei are in pairs in the proximal part of the body but it becomes singly towards the pointed-tail end. Coiled tail and covering Nuclei Tail Covering Onchocerca In pairs in the proximal part but becomes singly towards the tail Pointed ❌ Microfilaria of Onchocerca volvulus The microfilaria of Loa loa has a coiled tail with a Loa Loa Extending to the tip Coiled ✅ nuclei extending to the tip of the microfilaria. ○ Loa loa can also be diagnosed by extraction of Wuchereria No nuclei in its tail end Coiled ✅ ✅ worms from the eyes. Detected up to the Brugia terminal and subterminal Coiled end of its tail Note: Wuchereria bancrofti has larger and sweeping curves than Brugia spp. Microfilaria of Loa Loa Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 9 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited. 1. DIAGNOSIS AND TREATMENT OF ONCHOCERCIASIS VI. CASE STUDY 1.1 Diagnosis Given a 39-year old male patient who presented with Skin snip biopsy severe itchiness, hyperpigmented, and ○ Microfilaria detection hypopigmented skin lesions on the lower extremities: ○ Cannot detect light infection ○ Also used in assessing treatment effectiveness 1 What is the appropriate diagnostic test? Eye examination: for microfilaria detection in anterior chamber Clue: Consider the pigmentation of the patient’s skin, AKA Ultrasonography: adult worm detection leopard’s skin Observed in patients with Onchocerciasis 1.2 Treatment Answer: Skin snip biopsy Ivermectin (DOC), Tetracycline Skin lesions may have most probably occurred due to ○ Ivermectin is used in mass drug administration continuous scratching annually or biannually or individual treatment every 3-6 months. 2 Why does the patient experience pruritus? ○ It reduces the number of microfilariae within 48 hours and prevents the adult worms from releasing It is the body’s response to dead microfilaria in the microfilaria for up to 6 months. layers of the skin. Nodulectomy: removes the adult worms decreases 3 What is the appropriate treatment, if biopsy is exposure to microfilariae done and Onchocerca microfilariae are detected through microscopy? 2. DIAGNOSIS AND TREATMENT OF LOIASIS Ivermectin 2.1 Diagnosis Based on: History taking and physical examination are important to ○ Clinical history (calabar swelling, eye extraction of correctly diagnose and treat a patient. the worms, eosinophilia) ○ Microscopy: microfilaria detection Specimen for microscopy: blood (most common), urine, sputum, CSF 2.2 Treatment Diethylcarbamazine (DOC), Ivermectin, Albendazole Removal of adult L. loa V. TREATMENT FOR SKIN INFECTIONS Skin Infection Drug of Choice 1 Serpiginous skin lesions (Hookworms and Strongyloides species) Ivermectin 2 Onchocerciasis 3 Loiasis Diethylcarbamazine 4 Cysticercosis Praziquantel 5 Head and body louse infestation Permethrin 6 Pubic louse infestation Treatment for serpiginous skin lesions and onchocerciasis is Ivermectin. ○ The cutaneous larva migrans may heal spontaneously, but recurrence is still possible. Aside from the medication, nodulectomy is still advisable for a patient with onchocercoma since the skin lesion contains the adult worm. In a patient with Loiasis, removal of the adult worm of the eyes is part of the treatment aside from medication. Washing of linens, beddings, and clothes and placing it under the sunlight also help in killing the ectoparasites. Treatment of Cercarial dermatitis: ○ Self-limiting ○ Topical corticosteroids ○ Parenteral histamines for itchiness Microbio and Para - Mod 5 🏠 Parasitic Skin Infections 10 of 10 The use of trans, practice questions, and evals ratio must be used discreetly and social media/public exposure of the aforementioned shall be strictly prohibited.