This document discusses various parasitic infections that can manifest on the skin or subcutaneous tissues in humans. It covers protozoan infections like cutaneous leishmaniasis caused by Leishmania tropica complex parasites which presents as papules and ulcers on exposed areas. It also discusses filarial infections like loiasis caused by Loa loa which presents as migratory subcutaneous swellings, and helminth infections like cutaneous larva migrans caused by accidental skin penetration by larvae of animal hookworms or strongyloides. Laboratory diagnosis involves microscopy, culture, serology and molecular tests depending on the infecting parasite.

1. By Dr. Rakesh Prasad Sah
Assistant Professor, Microbiology

2. • Protozoan infections
• Cutaneous leishmaniasis
• Cutaneous amoebiasis
• Acanthamoeba skin lesions
• Trypanosoma chancre and
chagoma
• Sarcocystosis
• Cestode infections
• Muscular cysticercosis
• Trematode infections
• Cercarial dermatitis
• Ctaneous paragonimiasis
• Nematode infections
• Cutaneous filariasis
• Dracunculiaisis
• Trichinellosis
• Cutaneous larva migrans

3. • Apart from visceral leishmaniasis (VL), the leishmania
species  produce various cutaneous and mucocutaneous
manifestations.
• CL (Cutaneous leishmaniasis)
• Most common
• Global incidence 6-10 lakh new cases.
• 95% cases occur in America, Mediterranean basin, Middle East and
Central Asia
• MCL (Mucocutaneous leishmaniasis)
• Occur in Bolivia, Brazil, Ethiopia and Peru

4. • Cuased by Leishmania tropica complex
• Consist of three species
• L. tropica
• L. aethiopica
• L. major
• Life Cycle
• Is same as of L. donovani except that:
• Vector sandfly
• Habitat do not migrate to viscera
• Clinical Features
• Cutaneous leishmaniasis
• Condition known as “oriental sore”.
• Occurs on face and hands, begins with painless papule  nodular
 ulcerates.

5. • Leishmaniasis recidivans (LR):
• Granulomatous lesion  after healing of primary sore due to L. tropica
• Characterized by scaly, erythematous pappules and nodules, develop
in the centre or periphery of a previously healed sore.
• Diffuse cutaneou leishmaniasis
• Caused by L. aethiopica
• Characterized by lack of CMI response to parasite  widespread of CL
• May be confused with lepromatous leprosy (LL)
• Due to low CMI, montenegro test is negative

6. • Microscopy:- Amastigote form detected from active lesion
and touch preparation
• Culture
• Aspiration from the ulcers  NNN medium and Schneider’s Drosophila
medium  for isolation of promastigote forms
• Montenegro test
• Positive leishmanin skin test  delayed hypersensitivity,
• Negative  diffused CL

7. • Caused by
• Leishmania leishmania (L.L.) mexicana complex
• LL brziliensis complex
• LL chagasi
• Vector: Lutzomyia species
• Reservoir of infection: Dogs, foxes (Zoonotic)
• Amastigote form  R.E. cells of skin and mucous membrane
Leishmaina mexicana complex
• Causes CL and DCL
• Chiclero ulcer
• Specific form of CL
• Also called bay sore
• Characterized by persistent ulceration in pinna.

8. Leishmania viannia braziliensis complex
• Causes CL, similar to oriental sore but more severe, also
cause MCL
• Infects mucus membrane of nose, oral cavity, pharynx or
larynx
• Ulcerative lesion with erosion of the soft tissue and cartilages
 loss of lips, soft part of nose and soft palate (FIG)
• Gradually nasal septum destroyed  nasal collapse
• Lab diagnosis is same as Old world CL.

9. Loa Loa
• Causes infection of subcutaneous tissue and eyes
• Life Cycle
• Similar to W. bancrofti
• Clinical Feature
• Calabar swellings (repeated episodes of itchy swellings of the
body )
• Common form of loiasis.
• Also called fugitive swelling
• Swelling developing on extremities (knee or wrist)

10. • Ocular manifestations
• Conjunctival granuloma
• Edema of eye lid  proptosis (bulging)
• Complications
• Meningoencephalitis  occurs in DEC treated patients with
higher microfilaremia.
• Nephropathy
• Cardiomyopathy

11. • PBS
• Characteristics microfilarae.
• Blood collected at day time 10am to 3pm
• PCR
• Ab detection

12. • Causative agent of “river blindness”  endemic in west africa, south &
central America
• Dermatitis
• Onchocercoma :- formation of subcutaneous nodules, tend to develop
on head, neck and shoulders
• Ocular lesion:- bilateral blindness (river blindness), photophobia,
keratitis
• Lymphadeonopathy

13. • Also called as Guinea worm disease or dracunculiasis.
Life Cycle
• Definitive host Man
• Intermediate host  Cyclops
• Mode of transmission
• Drinking water from stagnant pools containing minute fresh water
crustaceans (Cyclops) infected with 3rd stage L3 larvae (infective form)

17. • Sign and symptoms appear approximately 1 year after the
infection when gravid adult female worm emerges near the
surface of the skin.
• Characterized by painful blister  female worm emerges 
local erythema, fever, nausea and pruritus.
• Most common sites  lower leg, ankle and foot
• Secondary bacterial infections may occur at the blister site.

18. • Detection of adult worm  blisters and X-ray for calcified
worms in deeper tissues
• Detection of L1 larvae
• When ulcerated leg  placed in container with cold water  large no.
of motile larvae discharged  which can be examined under
microscope.
• Ab detection
• PBS  Eosinophilia

19. • Trichinella spirallis causes trichinellosis.
• Is a zoonotic infection from domestic pigs or other carnivores.
• Life Cycle
• MOT by ingestion of raw or uncooked pork containing
infective form L1 larvae. 100-300 larvae req to initiate
infection.

23. • Clinical symptoms depends up on the phase of parasitic
invasion.
• Intestinal stage:
• Mostly asymptomatic
• Heavy load of parasite  watery diarrhoea  during 1st week after
infection
• Larval Migration (2nd week)
• Periorbital and facial edema is common
• Hemorrhages in the subconjuctiva, retina and nail beds (splinter
hemorrhages)
• Maculopapular rash
• Migration to heart, CNS and Lungs may occur but rare

24. • Muscle encystment
• Occurs 2-3 week after infection
• Common symptoms are myositis with myalgia, muscle edema and
weakness.
• Extraocular muscles most commonly involved, followed by biceps,
muslces of jaw, neck, lower back and diaphragm.

25. • Demonstration of larvae in Muscle biopsy obtained from
• Gastrocnemius
• Deltoid
• Biceps
• Direct slide technique
• Fresh muscle tissue  compressed between glass slides and
examined under low power microscope.
• Histological Examination
• Fresh muscle  digestion by pepsin

26. • Ab detection  IgG Ab
• Bachman intradermal test
• Prepared from Trichinella larvae  immediate induration & erythema
• Becomes positive in 2-3 weeks of infection and persist for life.
• Can not differentiate past and present infection.
• Other tests
• Blood tests
• Eosinophilia
• Elevated muscle enzymes  serum creatinine
• X-ray  calcified muscle cyst.

27. • CLM  skin lesions  produced by nematodes of lower animals
 infect man accidently.
• Agents
• Mainly by nonhuman hookworm species (A. brasiliensis, A. caninum and
A. ceylanicum)
• Rarely by strongyloides stercoralis, Ancylostoma duodenale and Nector
americanus.
• In lower animals: nematodes inf lower animals  larvae into
various organs (intestine) develop in adult worms  lay eggs 
cycle continues
• In humans: larvae of lower animal nematodes  accidently
infect man  not able to complete normal development (because
of unsulal host for them)  life cycle get arrested larvae wander
 skin & subcutaneous tissue producing a condition  called
cutaneous larva migrans (CLM) or creeping eruption.
• Another form of larvae migrans occurs called as “visceral larva
migrans”  life cycle arrested when larvae migrate to various

28. • Clinical Features
• Ground itch:- Pruritic maculopapular dermatitis and rashes (ground
itch) at the site of skin penetration of hookworm larvae.
• Larva currens:- Migrating strongyloides larvae produce the
pathognomic serpiginous urticarial rash called as larva currens near
the legs.
• Lab Diagnosis
• Larvae are usually not detected in skin biopsy.
• PCR
• Elevated Eosinophilia in PBS or sputum.
• Charcot-leyden crystals in sputum may be seen.

29. • Cutaneous amoebiasis
• Acanthmoeba skin lesions
• Trypanosoma chancre
• Chagoma
• Muscular sarcocystosis
• Cysticercosis
• Sparganosis
• Cercarial dermatitis
• Cutaneous paragonimiasis