Transcript Andrews’ chapter 20 - A.T. Still University

Andrews’ Chapter 20
pgs 526-547
JoAnne M. LaRow, D.O.
December 9, 2003
Phylum Protozoa
• One-celled organisms
• Divided into classes according to nature of
locomotion
• Class Sarcodina move by temporary projections of
cytoplasm (pseudopods)
• Class Mastigophora by means of one or more
flagella
• Class Ciliata by short, hair-like projections of
cytoplasm (cilia)
• Class Sporozoa with no special organs of
locomotion
Class Sarcondina
• Best known organism in class: ameba
• Entamoeba histolytica is ameba of medical
significance
• Amebiasis cutis begins as deep abscesses that
rupture
• These form ulcerations with distinct, raised,
cordlike edges and an erythematous halo approx.
20 cm wide
• Base is covered with necrotic tissue and
hemopurulent, glairy, pus-containing amebae
• Multiple large
ulcers
• Extensive
tissue
destruction
• Resembles
pyoderma
gangrenosum
Amebiasis Cutis
• Lesions may occur on trunk, abdomen, external
genitalia, buttocks, or perineum
• Abdominal lesions may arise from hepatic
abscesses
• All ages are at risk
• Intestinal amebiasis, with bloody diarrhea and
hepatic abscesses, may be present
• Chronic urticaria may be sole manifestation of
early amebiasis
• Organism may be found at base of lesion by direct
smear or shave bx
Histology-Amebiasis
• Necrotic ulceration with many lymphocytes,
neutrophils, plasma cells, and eosinophils
• E. histolytica is found in tissue, within
blood and lymph vessels
• Organisms measures 50-60 microns in
diameter
• Has a basophilic cytoplasm, a single
eccentric nucleus with a central karyosome
Diagnosis Amebiasis
• Organism is frequently demonstrable in fresh
material from base of ulcer
• Indirect hemagglutination test results remain
elevated for yrs after initial invasive disease onset
• Whereas, results of gel diffusion precipitation tests
and counterimmunoelectrophoresis become neg at
6 months
• This property can be used to test for recurrent or
active disease in persons coming from endemic
areas
Tx-Amebiasis
• Recommended is Metronidazole 750 mg
orally TID for 10 days, followed by
iodoquinol 652 mg TID for 20 days
• Surgical drainage for abscesses
Class Mastigophora
• Organisms are known as flagellates
• Many have undulating membrane with
flagella along crest
Trichomoniasis
• Trichomonas vulvovaginitis is a common cause of
vaginal pruritis with burning and frothy leukorrhea
• Vaginal mucosa appears bright red from
inflammation and may be mottled with
pseudomebranous patches
• Males may harbor organism and develop urethritis
and prostatitis, and occasionally balanoposthitis
• Neonates may acquire infection during passage
through birth canal, but require tx only if
symptomatic or if colonization lasts more than 4
weeks
• However, as this is otherwise nearly exclusively a
sexually transmitted disorder, trichomonas
vulvovaginitis in a child should make one suspect
sexual abuse
Trichomonas
• Tx Metronidazole 2.0 g in single oral dose TOC
• Alternatively, 500 mg twice daily for 7 days may
be given
• Warn pts not to drink alcohol for 24 hrs after last
dose because disulfiram type of effects of this med
• Male sex partners should be tx
• Metronidazole is contraindicated in pregnant
women-use clotrimazole intravaginally
• Colorless
pyriform
flagellate 5-15
microns long
• Demonstrated in
smears from
affected areas
• DIF is sensitive
and specific
Leishmaniasis
Leishmaniasis
• Three forms:
• A.) cutaneous form restricted to skin
• B.) mucocutaneous form affects both skin
and mucosal surfaces
• C.) visceral leishmaniasis that affects organs
of reticulo-endothelial system
Leishmaniasis
• Cutaneous leishmaniasis, American
mucocutaneous leishmaniasis, and visceral
leishmaniasis (kala-azar), which includes
infantile leishmaniasis and post-kala-azar
dermal leishmaniasis, are all caused by
morphologically and culturally
indistinguishable protozoa of the family
Trypanosomidae, called Leishmania
Cutaneous Leishmaniasis
• Several types of
lesions
• All tend to occur on
exposed parts as all
are transmitted by the
sandfly
Pathogenesis
• Organisms are obligate intracellular parasites
existing in two forms: promastigote and
amastigote
• In gut organisms multiply as extracellular
flagellated promastigotes
• Following migration to the proboscis, parasites are
inoculated (in promastigote form) via sandfly bite
• These transform into amastigotes within cells of
the reticuloendothial system in host- be it human,
rodent or canine
Life Cycle
Old World Leishmaniasis
• Limited to the skin
• Called Baghdad boil, oriental sore, leishmaniasis
tropica, birskra button, Delhi boil, Aleppo boil,
Kandahar sore, & Lahore sore
• May present in two ways: moist or rural type, a
slow growing, indurated, livid, indolent papule
which enlarges in a few months to form an ulcer
as much as 5 cm in diameter
• Spontaneous healing takes place within 6 months,
leaving a characteristic scar
• Contracted from rodent reservoirs such as gerbils
via the sand fly as vector
• Short incubation period-1-4 weeks
• Bagdad boil of 5 months’ duration
Old World Leishmaniasis
• Dry or urban type
• Has a longer incubation period (2-8 months
or longer)
• Develops more slowly, and heals more
slowly than the rural type
Leishmaniasis Recidivans
• Rarely, after initial or “mother “ lesion heals, there
may appear at the borders of healed areas a few
soft red papules covered with scales and having
the “apple jelly” characteristics of lupus vulgaris
• These spread peripherally on an erythematous
base and are called lupoid type
• Aka leishmaniasis recidivans
• Occurs most commonly with urban type caused by
L. tropica
New World Leishmaniasis
• Subtypes present of purely cutaneous
involvement are uta, pain bois, and bay sore or
chiclero ulcer
• Primary papule may become nodular, verrucous,
furuncular, or ulcerated, with an infiltrated red
border
• Subcutaneous peripheral nodules, which
eventually ulcerate, may signal extension of
disease
• A sporotrichoid pattern may occur with
lymphadenopathy, and nodes may rarely yield
organisms
• Recidivans lesions are unusual in New World form
of disease
• American cutaneous leishmaniasis
• Lesion of localized cutaneous leishmaniasis
presenting as an indurated nodule with an
ulcerated crateriform center
• Cutaneous leishmaniasis
• A well circumscribed ulcerated lesion on
the face of a child
• Cutaneous leishmaniasis
• Multiple ulcerated lesions on the legs of a
rural worker
• Circular scars at previous sites of cutaneous
leishmaniasis
• Often only sign of a previous infection
Chiclero Ulcer
• In Yucatan and Guatemala, a subtype of New
World disease exists: the chiclero ulcer
• Most frequently site of infection is the ear
• Lesions ulcerate and occur most frequently in
workers who harvest chicle for chewing gum in
the forests, where there is high humidity
• This form is a more chronic ulcer that may persist
for yrs, destroying ear cartilage and leading to
deformity
• Etiologic agent is L. mexicana and the vector, a
sandfly, Lutzomyia flaviscutellatta
Uta
• Uta is a term used by Peruvians for
leishmaniasis occurring in mountainous
territory at elevations of 1200 to 1800
meters above seas level
• Ulcerating lesions are found on exposed
sites, and mucosal lesions do not occur
Disseminated Cutaneous
Leishmaniasis
•
•
•
•
•
•
•
•
•
•
May be seen in New and Old World disease
Multiple nonulcerated papules and plaques
Chiefly on exposed surfaces
Caused by several subspecies of L. mexicana
L. aethiopica be etiology in Ethiopia and Kenya
Begins with a single ulcer, nodule, or plaque
Satellite lesions may develop & cover entire body
Disease is progressive and tx ineffective
Characterized by anergy to organism
Montenegro rxn is negative
• Disseminated cutaneous leishmaniasis
Epidemiology
• Cutaneous leishmaniasis is endemic in Asia Minor
& to a lesser extent in many countries around the
Mediterranean Sea
• Iran and Saudi Arabia have a high occurrence rate
• Purely cutaneous lesions are found in Central and
South America & 9 pts who acquired their disease
in Texas have been reported
• Children are affected most often, since immunity
is acquired from initial infection
• Deliberate inoculation on thigh is sometimes
practiced so that scarring on face- a frequent site
for Oriental sore-may be avoided
Pathogenesis
• Organism has an alternate life in vertebrate and an
insect host
• Man and other mammals such as dogs and
rodents are the natural reservoir hosts
• Host vectors are Phlebotomus sandflies in Old
World type and Phlebotomus perniciosus &
Lutzomyia sandflies for the New World cutaneous
leishmaniasis
• After insect has fed on blood, the flagellates
(leptomonas, promastigote) develop in gut in 8-20
days, after which migration occurs into the mouth
parts; from here transmission into humans occurs
by a bite
• In humans, flagella are lost and a leishmanial form
(amastigote) is assumed
Histopathology
• Typical features of an ulcer: heavy infiltrate of
histiocytes, lymphocytes, and a
polymorphonuclear leukocytes
• Numerous organisms are present ( mostly in
histiocytes), which are nonencapsulated and
contain a nucleus and a paranucleus
• Wright’s, Giemsa, and monoclonal antibody
staining may be helpful in identifying the
organisms
• Parasitized histiocytes form tuberculoid
granulomas in dermis
• Pseudoepitheliomatous hyperplasia may occur in
edges of ulcer
• Localized
cutaneous
leishmaniasis: a
diffuse infiltrate
extends into the
subcutis
• Epidermis is
ulcerated
• Mixed cell infiltrate with many plasma cells
and neutrophils but with histiocytes
predominating
• Organisms are seen within the histocytes
Diagnosis (cont’d)
• More sophisticated tests to diagnose and classify
subspecies involve detection of monoclonal
antibodies with immunoperoxidase, radiolabeling,
or fluorescenation, DNA probes, DNA buoyancy,
restriction-endonuclease fragment patterns of
kenetoplast DNA, restriction-frequent length
polymorphisms of unclear DNA, and isoenzyme
electrophoresis
Montenegro skin test
• Uses leishmanial antigen to induce a cellmediated response
• Can be used as a diagnostic method
• Cannot distinguish between past & present
infections
• Skin tests can be false-neg in anergic pts
with disseminated infections
Diagnosis
• Demonstration of organism in smears
• Parasites can be cultured from tissue fluid
• A hypodermic needle is inserted into normal skin
and to edge of ulcer base
• Needle is rotated to work loose some material and
serum, which is then aspirated
• Culture on Nicolle-Novy-MacNeal (NNN)
medium at 22 degrees- 35 degrees C
• Leishmanin intradermal test may be helpful in
nonendemic areas (Leishman-MontenegroDonovan)
• It becomes positive 3 months after infection
Treatment
• Spontaneous healing occurs, usually within 12-18
months, shorter for Old World disease
• Rationale for tx an ordinarily self-limited infection
include avoiding disfiguring scars in exposed
areas, avoiding secondary infection; controlling
disease in the population; and failure of
spontaneous healing; in diffuse cutaneous and
recidivans types, disease may persist for 20-40 yrs
if untreated
Tx (cont’d)
• In areas which localized cutaneous leishmaniasis
is not complicated by recidive or sporotrichoid
forms or mucocutaneous disease, tx with topicals:
Paromycin sulfate 15% plus methylbenzethonium
chloride 12%
• Ketoconazole cream under occlusion,
• Cryotherapy, local heat, and laser ablation, or
with intralesional sodium stibogluconate antimony
or emetine hydrochloride, may be effective and
safe
• Perilesional injections of interferon-gamma have
also been reported to be effective but are
expensive
Tx (cont’d)
• In pts who are immunocompromised or who
acquire disease in areas where mucocutaneous
disease may occur, systemic therapy is
recommended
• Many alternatives reported effective
• Sodium antimony gluconate (sodium
stibogluconate) solution given IV or IM20mg/kg/day in two divided doses for 28 days
• Repeated courses may be given
• Antimony n-methyl glutamine (Glucantime) is
used more often in Central and South America
because of its local availability
• Ketaconazole (600mg/day for 28 days),
itraconazole, dapsone, rifampin, and allopurinol
Tx (cont’d)
• Some of these have not been subjected to control
trials, as is true of most topical treatments
• Recidive and disseminated cutaneous types may
require prolonged courses or adjuvant interferon
therapy
• Amphotericin B may be used in antimonyresistant disease
• Control depends on success of anti-fly measures
taken by health authorities
Mucocutaneous Leishmaniasis
(Leishmaniasis Americana,
Espundia)
• Infection occurs at site of fly bite
• Initially a destructive ulcer
• Secondary lesions on the mucosa occur at the
same time or sometime during the next 5 yrs
• Earliest mucosal lesion is hyperemia of nasal
septum with subsequent ulceration
• Ulceration progresses to invade septum and later
paranasal fossae
• Perforation of septum eventually takes place
• Nose remains unchanged externally, despite
internal destruction
Clinical Features
• Initially only dry crust is observed, or a bright red
infiltration or vegetation on nasal septum
• Symptoms are obstruction and small hemorrhages
• Despite mutilation and destruction it never
involves nasal bones
• When septum is destroyed, nasal bridge and tip of
nose collapse, giving an appearance of a parrot
beak, camel nose, or tapir nose
• Four of the great chronic infections (syphilis,
tuberculosis, leprosy, and leishmaniasis) have a
predilection for the nose
• Ulcer may extend to lips and continue to advance
to pharynx, attacking soft palate, uvula, tonsils,
gingiva, tongue
• Leishmaniasis
americana
(mucocutaneous)
• Eventual mutilation is called espundia
• Two perpendicular grooves at union of osseous
palate and soft tissues, in mist of vegetative
infiltration of the entire pharynx is called the
palate cross of espundia
• Only in exceptional cases does American
leishmaniasis invade genital or ocular mucous
membranes
• Frequency of mucous membrane involvement is
variable
• In Yucatan and Guatemala it is an exception
• In other countries such as Brazil, it may occur in
80% of cases
Epidemiology
• Mucocutaneous leishmaniasis is
predominantly a rural and jungle disease
• It predominates in damp and forested
regions
• Can be contracted at any time of the yearrisk is highest just after the rainy season
• Affects all ages and races and both sexes
are equally affected
Histopathology
• In cases of granulomatous infiltration, when
intracellular parasites are found in histiocytes,
leishmaniasis is one of several disease to consider
• Others are: rhinoscleroma, histoplasmosis,
granuloma inginale, and toxoplasmosis
• Leishman-Donovan body is nonencapsulated and
shows a characteristic nucleus and parabasal body
• Touch smears stained with Giemsa are helpful in
may cases of cutaneous and mucocutaneous
leishmaniasis
Lab Findings
• Leishmania is demonstrated in cutaneous and
mucous membrane lesions by direct smears or
cultures
• Bx stained with Wright’s stain intracellular and
extracellular organisms with typical morphology
or two chromatic structures: nucleus & parabasal
body
• In later mucosal lesions there are less parasites
making ID difficult
• Cx via NNN medium is useful
• Intradermal Montenegro test is performed
• A suspension of 0.1-0.2 ml injected intradermally
Lab Findings
• A reading is made 48-72 hrs later
• Positive rxn is an area of induration greater than 5
mm in diameter 24-48 hrs after injection
• Test is specific and sensitive, 95% positive results
• But can be neg in early cases of disease
• But it is easy to find the parasites
• Cross rxn’s occur with certain forms of TB, but
are rare
• Montenegro test
in leishmaniasis
Treatment-Mucocutaneous
• Same as described for cutaneous leishmaniasis
except that antimony resistance is common
• Combination therapy using antimonials with other
drugs like rifampin
• Or adding immunomodualtors such as interferon
gamma or interleukin-2 may result in cure
• Amphotericin B tx may be needed
• Mucocutaneous
leishmaniasis
• Leishmaniasis: infiltrated “dry” inflammatory
plaques of leishmaniasis in a woman from Italy
• Spectrum of American cutaneous
leishmaniasis
• Disseminated
leishmaniasis:
multiple
erythematous
plaques with
scale-crust
Visceral Leishmaniasis (KalaAzar,Dumdum Fever)
• Earliest lesion is cutaneous nodule or
leishmanioma
• Occurs at site of initial sandfly inoculation
• Kala-azar means “black fever”
• Acquired its name because of patchy macular
darkening of skin caused by deposits of melanin
these develop later on in disease
• Patches are most marked over forehead and
temples, periorally, and on midabdomen
• Nodules of various
sizes
• Some pedunculated
• Pt has been tx for
kala-azar over 6
month period over 20
yrs ago
Visceral Leishmaiasis
• Primary target for parasite is reticuloendothelial
system; spleen, liver, bone marrow, and lymph
nodes
• Incubation period: 1-4 months
• And intermittent fever,temps ranging from 39
degrees- 40 degrees ushers in the disease
• Hepatosplenomegaly, agranulocytosis, anemia
thrombocytopenia
• Chills, fever, emaciation, wt loss, weakness,
epistaxis, and purpura develop
• Susceptibility to secondary infection may produce
pulmonary and GI infection, ulcerations in the
mouth (crancrum oris), and noma
• Death occurs in 2 yrs if untreated
Etiology
• L. donovani spp. Donovani, infantum, & chagasi
• These are parasite of rodents, canines, and humans
• They are nonflagellate oval organisms 3 microns
in diameter, known as Leishman-Donovan bodies
• In the sandfly it is a leptomonad form with flagella
Diagnosis
• Leishman-Donovan bodies may be present in
individuals with kala-azar of India
• Specimens for examination in descending order of
utility: spleen pulp, sternal marrow, liver tissue,
and exudate from lymph nodes
• Culture on NNN medium may also reveal
organisms
• The intradermal Montenegro test is also reliable
• For tx: general support measures; pentavalent
antimony is drug of choice
Post-Kala-Azar Dermal
Leishmanoid
• In kala-azar leishmanoid forms (amastigote) may
be widely distributed throughout apparently
normal skin
• During & after recovery a special form of dermal
leishmaniasis known as post-kala-azar dermal
leishmanoid appears
• Condition appears during or shortly after tx in
African form
• Appearance may be delayed up to 10 yrs after tx
in Indian form
• It is common in India, occurring in up to 20% of
pts; in Africa only 2% develop it
Post-Kala-Azar Dermal
Leishmanoid
• Two constituents of eruption: a macular, depigmented eruption found mainly on face, arms,
and upper part of trunk; a warty, papular eruption
in which amastigotes can be found
• Pts may act as a chronic reservoir of infection-it
may persist for up to 20 yrs
• Condition closely resembles leprosy
• Evidence that pts who will develop this have a
marker interleukin-10 in their keratinocytes and
sweat glands
• Post kala-azar
dermal
leishmaniasis
Vicerotropic Leishmaniasis
• 1 report of 8 soldiers developing systemic
infection with L. tropica while fighting in
Operation Desert Storm in Saudi Arabia
• None had symptoms of kala-azar, but 7 had fever,
fatique, malaise, cough, diarrhea, or abdominal
pain
• 1 pt was aymptomatic
• None had cutaneous disease
• In 7 diagnostic tests were pos. via bone marrow
aspiration and 1 via lymph node aspiration
• 5 of 6 tx’d with sodium stibogluconate improved
Human Trypanosomiasis
• Three species are pathogenic to humans:
Trypanosoma gambiense and T. rhodesiense in
Africa; T. cruzi in America
• Early stages of African trypanosomiasis a chancre
may occur at site of tsetse fly bite
• Next erythema with circumscribed swellings of
angioedema, enlargement of lymph glands, fever,
malaise, headache, and joint pain occurs
• In West African (Gambian) form, illness is chronic
over yrs with progressive deterioration
• In East African (Rhodesian) form illness is acute
with a stormy, fatal course of weeks to months
Chagas’ disease
• Reduviid bug (kissing
bug, assassin bug)
usually bites at night,
frequently at
mucocutaneous
junctions, where bug’s
infected feces are
deposited when it
feeds
American Trypanosomiasis
• Unsuspecting sleeping person rubs the feces into
the bite and becomes infected
• If bite occurs around the eye Romana’s sign
develops; this consists of unilateral conjunctivitis
and edema of eyelids, with an ulceration or
chagoma in area
• Bite becomes markedly swollen and red whether
trypanosomes are involved or not
• Acute Chagas’ disease is usually mild with fever,
malaise, edema of face and lower extremities and
generalized lymphadenopathy
Chagas’ Disease
• Prevalent in Central and South America
from the U.S. to Argentina and Chile;
highest incidence is Venezuela, Brazil,
Uruguay, Paraguay, and Argentina
• Approx. 29% of all male deaths in 29-44 yr
age group in Brazil are ascribed to Chagas’
disease
Tx: Chagas’ Disease
• Before CNS involvement occurs, suramin, a
complex, non-metal-containing, organic
compound, is tx of choice
• For American trypanosomiasis, tx is of limited
efficacy
• Nifurtimox and benzimidazole clear the
parasitemia and reduce severity of acute illness
• There is a high incidence of adverse effects
• Conservative tx is most appropriate for pt with
CHF from Chagas’ myocarditis
• GI complications(megaesophagus & megacolon)
may be tx’ed surgically
Chronic Chagas’
• Occurs in 10-30% of infected persons yrs to
decades later
• Heart (myocarditis, arrhythmias,
thromboembolism, and cardiac failure) &
GI (megaesophagus and megacolon)
• In the remaining infected but asymptomatic
phase pts may pass the disease through
transfusion
African Trypanosomiasis
• In West Africa due to Trypanosoma brucei
gambiense infection
• In East Africa caused by Trypanosoma brucei
rhodesiense infection
• Vectors are usually several species of tsetse flies
• Cutaneous manifestations include a localized bite
rxn (‘trypanosomal chancre’) & an annular
eruption coinciding with fever spike
Rhodesian Trypanosomiasis
• Endemic among cattle-raising tribes of East
Africa
• With savannah habitat of the vectors
determining its geographic distribution
• Wild game and livestock are reservoir hosts
as well as humans
• The tsetse fly Glossina morsitans is the
principal vector
Gambian Trypanosomiasis
• Humans are the only vertebrate host and the
palpalis group of tsetse flies is the invertebrate
host
• These flies are found close to water
• Their fastidious biologic requirements restrict
their distribution & distribution of disease
• Incidence is seasonal, with humidity and
temperature being determining factors
• Highest incidence is in males 20-40 yrs old in
tropics of West and Central Africa
• Bite rxn earliest
lesion
• Called
trypanosomal
chancre
• Resembles a boil
but is painless
• Aspirated fluid
contains actively
dividing
trypanosomes
CLASS SPOROZOA
Toxoplamosis
Toxoplasmosis
• A zoonosis caused by a parasite protozoan
• Called Toxoplasma gondii
• Manifestations vary (mild-severe);infection may
be congenital or acquired
• Congenital infection occurs from placental
transmission-abortion or stillborn may result
• Congenital toxoplasmosis presents with triad of
hydrocephalus, chorioretinitis, and cerebral
calcification
• In addition there may be hepatosplenomegaly and
jaundice
• Skin changes are rare and nonspecific
Congenital Toxoplasmosis
• Macular and hemorrrhagic eruptions
predominate
• Blueberry muffin lesions, reflect
dermatoerythropoesis may occur
• Abnormal hair growth and exfoliative
dermatitis may also occur
Acquired Toxo
• Cutaneous and subcutaneous nodules,
macular, papular, and hemorrhagic
eruptions, followed by scarlatiniform
desquamation, roseola-like, erythema
multiforme-like, and lichen planus-like
eruptions as well as exfoliative dermatitis
• Eruption is usually accompanied by high
fever and general malaise
Acquried Toxo
• Diagnosis of acquired toxo is important to:
• healthy pregnant women concerned about recent
exposure
• adults with lymphadenopathy, fever, and myalgia,
acute or chronic, who might have other serious
diseases, such as lymphoma;
• immunocompromised persons: such pts with
AIDS, in whom toxoplasmosis might be fatal
• it is the most common cause of focal encephalitis
in pts with AIDS
Acquired Toxo
• 20% of pregnant women have already had the
disease and are protected
• They are identified by a positive test very early in
pregnancy, or just before pregnancy
• A high titer just before the twentieth week of
gestation might be an indication for tx or such a
test before delivery-tx of infant
• Immunofluorescence or complement fixation tests
may be helpful
Toxoplasmosis
• Diagnosis in adults is made by rising or high
antibody test
• Characteristic histologic changes in lymph nodes
may be confirmatory
• In congenital cases and rarely in acquired ones,
chorioretinitis may occur a decade or more after
infection
• In congenital infection chorioretinitis is usually
bilateral, whereas in acquired type it is usually
unilateral
Toxoplasmosis
• Toxoplasma gondii is a crescent-shaped, oval, or
round protozoan
• Can infect any mammalian or avian cell
• Disease often is acquired through contact with
animals-cats usually
• Two major routes of transmission: oral and
congenital
• Meats used for human consumption may contain
tissue cysts, therefore serving as a source of
infection when eaten raw or undercooked
• No evidence of human –to-human spread other
than from mother to fetus
Toxo:diagnosis
• Cannot be made clinically alone
• Must isolate the organism
• Protozoa can be found in tissue sections, smears,
or body fluids by Wright’s or Giemsa stain;
characteristic lymph node histology; serologically
• Mouse inoculation with properly prepared tissue,
ie lymph node, spinal fluid, or peripheral blood,
may isolate and identify the parasite if stained
with Giemsa or Wright’s stain
• Antibodies are most commonly detected by SabinFeldman dye test, which becomes positive 10-14
days after initial infection
• Maximum titer is attained in 4-5 weeks
Toxoplasmosis
• Worldwide distribution, with several areas
having a greater than 90% seropositivity
• Occurs in eastern U.S. more frequently than
in western U.S.
• Resevoirs of infection reported have been
dogs, cats, cattle, sheep, pigs, rabbits, rats,
pigeons, and chickens
Toxoplasmosis:tx
• Combination of pyrimethamine (Daraprim), and
sulfadiazine act synergistically and form an
effective tx
• Dosages and total tx time vary according to age
and immunologic competence of infected pt
• Pyrimethamine is a folic acid antagonist, so
concomitant folinic acid therapy is recommended
Phylum Cnidaria
Jellyfish
Hydroids
Corals
Sea anemones
All are radial marine animals
Portugese Man-of-War
Dermatitis
• Stings are
characterized by linear
lesions
• Erythematous,
urticaria, and even
hemorrhagic
• Common sites are
forearms, sides of
trunk, thighs, and feet
Portuguese Man-of-War
Dermatitis
• Usual local manifestations are sharp, stinging, and
intense pain
• Internally there may be severe dyspnea,
prostration, nausea, abdominal cramps,
lacrimation, and muscular pains
• Death may occur if areas stung are large in
relation to size of pt
• Fluid of nematocytes contain toxin that is carried
into human victim through barbs along the tenticle
• Venom is a neurotoxic poison that can produce
marked cardiac changes
Portugese Man –of-War
Dermatits
• Each Portuguese man-of-war is a colony of
symbiotic organisms consisting of a blue to red
float or pneumatophore with a gas gland
• Several gastrozooids measuring 1-20 mm,
reproductive polps, and fishing tentacles bearing
the nematocytes from which barbs are ejected
• Hydroid is found mostly along southeastern
Florida coastline and in Gulf of Mexico, and on
windward coasts throughout the mid-Pacific and
South Pacific
Jellyfish Dermatitis
• Produces similar lesions
of man-of-war, except not
as linear
• Delayed and persistent
lesions were described by
Reed et al from stings
incurred in the Aegean and
Caribbean areas
• Prolonged hypersensitivy
reactions have been
reported associated with
specific antijellyfish
immunoglobulins
• The most dangerous of all is Chironex
fleckeri, the Australian sea wasp
• It is colorless and transparent
• Its sting is often fatal
• Another seas wasp Carybdea marsupialis,
is much less dangerous and occurs in
Caribbean
Seabather’s eruption
• An acute dermatitis
beginning a few hrs after
bathing in the ocean
• Erythematous macules and
papules appear that may
develop into pustules or
vesicles
• Urticarial plaques may be
present less commonly
• Crops of new lesions may
occur for up to 72 hrs
• Eruption persists for 10-14
days on average
• It is quite pruritic
• Seabather’s eruption occurs along the coast of the
Atlantic Ocean and affects covered areas of body
• Cnidatian larvae become entrapped under bathing
suit and the nematocyst releases its toxin because
of external pressure
• Buttocks and waist are primarily affected, with
breast also involved in women
• It has been noted that seabathers who take off their
suit and shower soon after leaving the water may
limit the eruptions
Hydroid, Sea Anemone, and
Coral Dermatits
• Pts contacting the small marine hydroid Halecium
may develop a dermatitis
• These organisms grows like a centimeter-thick
coat of moss on submerged portions of vessels or
pilings
• Sea anemones produce reactions similar to those
produced by jellyfish and hydroids
• Coral cuts are injuries caused by exoskeleton of
corals, Milleporina
• Milleporina have a largely undeserved reputation
for becoming inflamed and infected & for delayed
healing
Milleporina
• The combination of implantation of
fragments of coral skeleton and infection
(since cuts occur moat commonly on feet)
probably accounts almost entirely for these
symptoms
• Detoxification as soon as possible after
injury is advisable for all of these types of
stings or cuts
Tx of Stings & Cuts
• All therapy is the same: fire corals, hydroids,
jellyfish, sea anemone
• Soak wound in 5% acetic acid (vinegar)
• Leading alternative is isopropyl alcohol (40-70%)
• Meat tenderizer has been reported to be effective
but not as reliable as vinegar
• Detoxicant should be applied continuously for at
least 30 mins
Tx-continued
• Next, any large visible tentacles should be
removed with forceps in a double-gloved hand
• Remaining nematocytes should be removed by
applying a layer of shaving cream and shaving
area gently
• Fresh water and abrasion will worsen the
envenomation
• Topical anesthetics or steroids may be applied
after decontamination
• Systemic rxn’s may occur either through large
amounts of venom or a previously sensitizing
exposure from which anaphylaxis may result
• Specific antivenin is available for the boxjellyfish
Sponges and Bristleworms
• Sponges have horny spicules of silicon dioxide
and calcium carbonate
• Some sponges produce dermal irritants such as
halitoxin and okadaic acid
• Others may be colonized by cnidaria
• Allergic or irritant rxn’s may result
• Bristleworms may also produce stinging
• All of these may be tx’d by first using adhesive
tape to remove spicules, then applying vinegar
soaks and then applying a topical steroid
Sea Urchin Injuries
• Puncture wounds inflicted by brittle, fragile spines
of seas urchins, mainly genus Diadema or
Echinothrix, are stained blue-black by the spines
and may contain fragments of the spines
• These are rarely large enough to require removal
• Foreign-body or sarcoidlike granulomas may
develop
• Injuries from spines of genus Tripneustes have
been reported to cause fatal envenomation-but this
genus is not found on U.S. coasts
• Envenomations may occur from stingrays,
scorpionfish, stonefish, catfish, & weaverfish
Treatment
• These wounds should be immersed in nonscalding
water (45 degrees C) for 30-90 mins or until pain
subsides
• Calcified fragments may be visible on x-ray
evaluation, with fluoroscopy guiding extraction of
spines, especially on hands and feet
• Debridement and possibly antibiotic therapy for
deep puncture wounds of hands and feet is
recommended
• There is a specific antivenin for stonefish stings
Seaweed Dermatitis
• Caused by marine alga
• Dermatitis occurs 3-8 hrs after individual emerges
from ocean
• Distribution is in parts covered by a bathing suit:
scrotum, penis, perineum. And perianal area
• Caused by marine plant-Lyngbya majuscula
Gomont
• Observed on in bathers off windward shore of
Oahu, Hawaii
• Prophylaxis refraining from swimming in waters
turbid with such algae
• Shower within 5 mins after swimming; active tx
same as acute burns
Dogger Bank Itch
• Eczematous dermatitis caused by sea
chervil, Alcyondium hirsutum
• A seaweed-like animal colony
• These mosses or sea mats are found on the
Dogger Bank, an immense shelflike
elevation under the North Sea between
Scotland and Denmark
Phylum Platyhelminthes
Flatworms: two classes:
Trematodes &Cestodes
Cestodes: segmented, ribbon-shaped
flatworms that inhabit intestinal tract
as adults and involve subcutaneous
tissue, heart, muscle, eye in larval
form
Encased in a sac eventually becoming
calcified
CLASS TREMATODA
• Schistosome cercarial dermatitis
• Severely pruritic, widespread, papular dermatitis
• Caused by cercariae of schistosomes for which
humans are not hosts (usually waterfoal and
rodents like muskrats)
• Eggs in excreta of these animals are deposited in
water then hatch into swimming miracidia
• Miracidia enter a snail, where further development
occurs
• From snail, free-swimming cercariae emerge to
invade human skin on accidental contact
Schistosome Cercarial Dermatitis
• These swimming, colorless, multi-cellular
organisms are less than a millimeter long
• Exposure to cercariae occurs when swimming or
more often wading in water containing them
• They attack by burrowing into skin, where they
die
• Species that cause this eruption cannot enter the
bloodstream or deeper tissue
• After coming out of water a transient
erythematous eruption appears
• After a few hrs eruption subsides and pruritis too
• After quiescent period of 10-25 hrs symptoms
recur, erythematous macules & papules develop in
exposed areas
• After several days the dermatitis heals
spontaneously
• There are two types: freshwater swimmer’s
itch & saltwater marine dermatitis or clamdigger’s itch
• It is not communicable
• Can be prevented by thoroughly washing
and drying with a towel after exposure
Visceral Schistosomiasis
(Bilharziasis)
• Cutaneous manifestations begin with mild itch and
a papular dermatitis of feet and other parts after
swimming in polluted streams containing
cercariae
• Types of schistosomes causing this can penetrate
into bloodstream and eventually inhabit venous
system draining the urinary bladder (Schistosoma
haematobium) or intestines (S. mansoni or S.
japonicum)
• After an asymptomatic incubation period, there
may be a sudden illness with fever and chills,
pneumonitis, and eosinophilia; petechial
hemorrhages may occur
Cutaneous Schistosomiasis
• Granulomas most frequently involve genitalia,
perineum, and buttocks
• These bilharziomas usually caused by eggs of S.
haematobium or S. mansoni
• Vegetating, soft, cauliflower-shaped masses occur
• Fistulous tracts and extensive hard masses occur;
these are riddled by sinuses exudating a
seropurulent discharge with characteristic odor
• Phagedenic ulcerations and pseudoelephantiasis of
scrotum, penis, or labia may occur
• Schistosomal granulomas of the scrotum
Cutaneous Schistosmiasis
• Infrequently, ectopic or extra-genital lesions
may occur mainly on trunk
• This is a papular eruption tending to group
in plaques and become darkly pigmented
and scaly
Cutaneous Schistosomiasis
Katayama Fever
• Severe urticarial eruption
• Aka urticarial fever
• Frequently present along with a S. japonicum
infection
• Occurs at beginning of oviposition,4-8 weeks after
infection
• Occurs mainly in China, Japan, Philippines
• Fever, malaise, abdominal cramps, arthritis, and
liver and spleen involvement are seen
• Felt to be a serum sickness-like rxn
Katayama Fever
• Prevention includes: reducing infection sources,
preventing contamination by human excreta of
snail-bearing waters, control of snail hosts,
avoiding exposure to cercaria-infested waters
• Prophylactic measures are still being sought after
• Tx: praziquantel (Biltricide) 20 mg/kg orally for
each of two treatments in 1 day= TOC
• S. japonicum requires 3 doses in 1 day
• Schistosomicides exhibit toxicity for host as well
as for parasite
• Risk of undesirable side effects may be enhanced
by concomitant cardiac, renal, or hepatosplenic
disease
Cysticerosis Cutis
• Natural intermediate host of pork tape worm is the
pig
• But humans may act in this role
• Tapeworm known as Taenia solium
• Larval stage of T. solium is Cysticercus cellulosae
• Infection takes place after ingestion of food
contaminated with eggs or by reverse peristalsis of
eggs or proglottides from intestines to stomach
• Eggs hatch, freeing the oncospheres
• Onchospheres enter general circulation and form
cysts in various parts of body: striated muscle,
brain, eye, heart, and lung
Cysticercosis Cutis
• In subcutaneous tissues lesions are usually
painless nodules containing cysticerci
• These are more or less stationary, numerous and
often calcified (therefore seen on x-ray)
• Pain and ulceration may occur
• Disease is most prevalent in countries where pigs
feed on human feces
• Ddx: gumma, lipoma, epithelioma
• Positive dx is via incision and examination of
interior of calcified tumor, where parasite will be
found
Cysticercosis Cutis
• Tx: Praziquantel 10mg/kg of body wt=TOC
for intestinal tapeworms
• Five times this dose for 15 days is required
if CNS is involved
• This regimen has no effect on calcified
parasites-these need to be surgically
removed
Sparganosis
• Caused by larva of tapeworm of species
Spirometra
• Adult tapeworm lives in intestines of dogs and
cats
• Rare tissue infection
• Occurs in two forms:
• Application sparganosis-occurs when an ulcer or
infected eye is poulticed with flesh of an infected
intermediate host-larvae become encased in small
nodules in the infected tissues
• Ingestion sparganosis: occurs when humans ingest
inadequately cooked meat, such as snake or frog,
or when humans drink water contaminated with
cyclops which are infected with plerocercoid
larvae
Sparganosis
• 1-2 slightly pruritic or painful nodules may
form in subcutaneous tissue or on the trunk
and legs
• Humans are the accidental intermediate host
of the Sparganum which is the alternative
name for the plerocercoid larva
• Tx is surgical removal or ethanol injection
of infected nodules
Echinococcosis
• Also known as hydatid disease
• In humans, infection is produced by ova reaching
mouth by hands, in food, or from containers soiled
by ova-contaminated feces from an infected dog
• Leading to Echinococcus granulosus infestation of
liver and lungs
• Soft, fluctuating, semitranslucent, cystic tumors
may occur in skin, sometimes in supraumbilical
area as fistulas from underlying liver involvement
• These tumors become fibrotic or calcified after the
death of the larva
• Eosinophilia or intractable urticaria and pruritus
may be present
Echinococcosis
• Tx: excision with care not to rupture the
cyst
• Albendazole combined with percutaneous
drainage may also be used
Leeches
• Marine, freshwater, or terrestrial types
• After attaching to skin, they secrete an
anticoagulant, hirudin
• They then engorge themselves with blood
• Local symptoms at site of bite include: ulceration,
bullae, hemorrhage, pruritus, whealing, necrosis
• Allergic rxn’s including anaphylaxis may occur
• They may be removed by applying salt, alcohol, or
vinegar, or by use of a match flame
• Bleeding may be stopped by direct pressure or by
applying a styptic pencil to site
• Medicinally leeches may be used to salvage tissue
flaps threatened by venous congestion
CLASS NEMATODA
Enterobiasis
Hookworm
Creeping Eruption
Gnathostomiasis
Larva Currens
Dracunculiasis
Filariasis
Enterobiasis
•
•
•
•
Pinworm, seatworm, oxyuriasis
Main complaint is nocturnal pruritus ani
Seen most frequently in children
Vagina may become infested with gravid
pinworms
• Restlessness, insomnia, enuresis, irritability
may be seen
Enterobiasis
Enterobiasis
• Cause by roundworm Enterobius vermicularis
• May infest small intestines, cecum, and large
intestine of humans
• Worms, especially gravid ones, migrate toward
rectum and at night emerge to peri-anal and
perineal areas to deposit thousands of ova
• Worm then dies outside the intestines
• These ova are carried back to mouth of host on the
hands
• Larvae hatch in duodenum and migrate into the
jejunem and ileum where they reach maturity
• Fertilization occurs in the cecum, thus completing
the life cycle
Enterobiasis
• Humans are only known host of pinworm
• It is probably the widest distributed of all
helminths
• Infection occurs from hand-to-mouth
transmission, often from handling soiled clothes,
bedsheets, etc
• Ova under the fingernails are a common source
• Ova may be airborne and collect in dust on
furniture and floors
• Investigation may show that all members of the
family of an affected person harbor the infection
• It is common in orphanages and mental
institutions and among people living in communal
groups
Enterobiasis
• Diagnosis is made by demonstration of ova in
smears taken from anal region early in morning
before defecation
• With pt in knee-chest position, a smear is obtained
from anus with a small eye curette
• This is placed on a glass slide with a drop of saline
solution
• It is also possible to use Scotch tape, looping the
tape sticky-side out over a tongue depressor and
then pressing it several times against perianal
region
• Tape is then smoothed out on a glass slide
• A drop of a solution containing iodine in xylol
may be placed on the slide before the tape to aid in
detection of ova
Enterobiasis
• These tests should be repeated on 3 consecutive
days to rule out infection
• Ova may be detected under the fingernails of
infected persons
• It is also feasible to identify dead pinworms in the
stool
• Tx: Albendazole 400 mg or mebendazole 100 mg
repeated in 2 weeks
• Personal hygiene and cleanliness at home ar
important
• Cut fingernails short, and scrub frequently
• Sheets, underwear, towels, pajamas, and other
clothing should be laundered throughly and
separately
Hookworm Disease
• AKA ground itch, uncinariasis, ancylostomiasis,
necatoriasis
• Earliest skin lesions are erythematous macules and
papules, which become vesicles in a few hrs
• These are itchy and occur on soles, toe webs, and
ankles
• Contents of vesicles become rapidly purulent
• These lesions are produced by invasion of the skin
by Ancylostoma or Nector larvae and precede the
generalized symptoms of disease by 2-3 months
• Cutaneous lesions last less than 2 weeks before
larvae continue their human life cycle
• Eosinophilia may rise to 40% around 5th day of
infection
Hookworm Disease
• Onset of constitutional symptoms is accompanied
by progressive iron deficiency anemia and debility
• Urticaria often occurs
• Skin becomes dry and pale or yellowish
• Hookworm is a specific communicable disease
caused by Ancylostoma duodenale or Necator
americanus
• In soil they become infective larvae in 5-7 days
• Tiny larvae (which can scarcely be seen with a
small pocket lens), when they come into
accidental contact with bare feet, penetrate skin
and reach capillaries
Hookworm Disease
• Larvae are carried in circulation to lungsthrough capillary walls into bronchi-move
up trachea to pharynx and being swallowed,
eventually reach their habitat in the small
intestine
• Here they bury their heads in mucosa and
begin their sexual life
Hookworm Disease
• Prevalent in most tropical and subtropical
countries and is often endemic in swampy and
sandy localities in temperate zones
• In temperate zones larvae are killed off each
winter and soil is re-contaminated from humans
the following summer
• Nector americanus prevails in Western
Hemisphere, Central and South Africa, South
Asia, Australia, & Pacific islands
Hookworm Disease
• Defecation habits of infected individuals in
endemic areas is responsible for its widespread
distribution
• Also cause is human feces for fertilization in may
parts of the world
• The climate is such that people go barefoot due to
heat
• Finding the eggs establishes a diagnosis
• Ova appear in feces 5 weeks after onset of
infection
Hookworm
Hookworm Disease
• Tx: expulsion of parasites from body and tx
by preventing re-infection through proper
disposal of human feces
• Albendazole 100mg once or mebendazole
100 mg BID for 3 days is effective
• Prophylaxis depends on preventing fecal
contamination of soil
Creeping Eruption
• AKA larva migrans
• Twisting, winding linear skin lesions produced by
burrowing of larvae
• Victims are people who go barefoot at beaches,
children playing in sandboxes, carpenters and
plumbers working under homes, and gardeners
• Most common areas involved are feet, buttocks,
genitals, and hands
• Onset characterized by local itching and
appearance of papules at sites of infection
Larva Migrans
• Intermittent stinging pain occurs, and thin,
red, tortuous lines are formed in skin
• Migrations begin 4 days after inoculation
and progress at a rate of 2 cm per day
• Larvae may remain quiescent for several
days or even months
• Linear lesions are often interrupted by
papules marking sites of resting larvae
Larva Migrans
• As eruption advances, old parts tend to fade, but
sometimes there are purulent manifestations
caused by secondary infection; erosions and
excoriations caused by scratching may occur
• If disease is not interrupted by tx larvae usually
die in 2-8 weeks, with resolution of eruption
• Rarely eruption has persisted for up to 1 yr
Larva Migrans
• Majority of cases in this country are caused by
penetration by larvae of a cat and dog hookworm
Ancylostoma braziliense
• This is acquired from body contact with excreta of
dogs and cats
• This is common along coast of southwestern US
• Tx: Ivermectin 150 micrograms/kg as a single 12mg dose or albendazole 200 mg BID for 3 days
• Criteria for successful tx are relief of symptoms
and cessation of tract extension- usually occurs
within a week
• Topical thiabendazole 10% oral suspension QID
will help with pruritus and tracts become inactive
within 1 week
Gnathostomiasis
• Characterized by migratory, intermittent,
erythematous, urticarial plaques
• Each episode of painless swelling lasts from 7-10
days and recurs every 2-6 weeks
• Movement of underlying parasite may be as much
as 1 cm/hr
• Total duration of illness may be 10 yrs
• Histopathologic exam of skin swelling will
demonstrate eosinophilic panniculitis
• Clinical manifestation has been called larva
migrans profundus
• Nematode Gnathostoma dolorosi or spingerum is
cause
Gnathostomiasis
• Most cases occur in Asia
or South America
• Eating raw flesh from
second intermediate host,
most commonly
freshwater fish, in form of
sashimi & ceviche allows
humans to become
definitive host
• One report of eating raw
snake flesh
• As the larval cyst in the
flesh is digested, larva
becomes motile and
penetrates gastric mucosa,
usually within 24-48 hrs
of ingestion
• Symptoms then occur as
migration of parasite
continues
• Surgical removal is TOC
if parasite can be located
• This can be combined
with albendazole 400 mg
daily or BID for 21 days
Larva Currens
• Intestinal infections with Strongloides stercoralis
may be associated with a perianal larva migrans
syndrome, called larva currens
• Named because of the rapidity of larval migration
currens means running or racing
• An auto-infection caused by penetration of
perianal skin by infectious larvae as they are
excreted in feces
• An urticarial band is primary lesion of cutaneous
strongyloidiasis
Larva Currens
• Often is a chronic disease
• Has been reported to last 40 yrs or more
• Symptoms include: abdominal pain, diarrhea,
peripheral eosinophilia
• Skin lesions originate within 30 cm of anus
• Extend as much as 10cm/day
• Fatal cases of hyper-infection occur in
immunocompromised pts
• Parasite load increases dramatically and can
produce fulminant illness
• Widespread petechiae and purpura and chronic
urticaria may be a presenting sign of
dissemination
Larva Currens
• Tx: ivermectin 200 micrograms/kg/day for
2 days or albendazole 400 mg/day for 3
days=TOC
• Immunosuppressed hosts may be tx with
thiabendazole 25 mg/kg BID for 7-10 days
Dracunculiasis
• Guinea worm disease or medina worm
• Endemic in India, southwest Asia, northeast South
America, West Indies, and Africa
• Caused by Dracunculus medinensis contracted
through drinking water contaminated with infected
water fleas in which Dracunculus is parasitic
• In stomach, larvae penetrate into mesentery where
they sexually mature in 10 weeks
• Female worm burrows to cutaneous surface to
deposit her larvae and causes skin manifestations
• As worm approaches surface it may be felt as a
cordlike thickening and forms an indurated
cutaneous papule
Dracunculiasis
• Papule may vesiculate and a painful ulcer
develops, usually on the leg
• Worm is often visible
• When parasite comes into contact with
water, the worm rapidly discharges its
larvae, which are ingested by water fleas
(Cyclops), contaminating the water
Dracunculiasis
• Cutaneous lesion is usually on lower leg, but may
occur on genitalia, buttocks, or arms
• There may also be urticaria, gastrointestinal
upsets, eosinophilia, and fever
• Disease may be prevented by boiling water before
drinking, providing safe drinking water through
boreholes, or filtering water through mesh fibers
• Native tx consists of gradually extracting the
worm a little each day, with care not to rupture it
• If ruptures larvae escape into tissues and produce
fulminating inflammation
• Surgical removal is TOC
• Metronidazole 500 mg/day resolves inflammation
and permits easier removal of worm; so does
warm water immersion
Filariasis
• Elephantiasis Tropica (elephantiasis Arabum)
• Widespread tropical disorder caused by infestation
by filarial worms of Wuchereria bancrofti, Brugia
malayi, or B. timori
• Characterized by lymphedema
• Resulting in hypertrophy of skin & subcutaneous
parts
• Enlargement of affected areas usually legs,
scrotum, labia majora
• More common in men than women
Filariasis
• Onset characterized by recurrent attacks of acute
lymphangitis
• Episodes last days –weeks
• Occurs for months-yrs
• After each attack swelling subsides only partially
• As recrudescences supervene thickening and
hypertrophy worsen
• Overlying epidermis becomes stretched, thin,
shiny
• Over yrs becomes leathery, insensitive, verrucous
or papillomatous from secondary pyogenic
infection
Filariasis
• Involvement may then involve scalp, vulva,
penis, female breasts, arms
• Legs are usually affected symmetrical
manner
• Thickening becomes massive and
pachydermatous
• Thickened integument hangs in apposing
folds between which there is a fetid exudate
• Scrotal involvement causes area to become
enormous and penis becomes hidden in it
• Skin, first glazed, later becomes coarse and
verrucous or ulcerated or gangrenous
• Resistant urticaria may occur
• Filarial orchitis and hydrocele are common
• Testicle may enlarge rapidly to apple size and can
be painful
• Swelling may subside within a few days,
enlargement may be permanent
• Resulting obstruction and dilation of thoracic duct
may occur; obstruction of lower abdominal
tributaries into urinary tract, chyle appears in urine
Filariasis
• Lobulated swellings of inguinal and axillary
glands, called varicose glands occur
• These are caused by obstructive varix and dilation
of lymphatic vessels
• Filaria are transmitted person-to-person by bites of
mosquitoes
• Culex, Aedes, and Anopheles species
• Adult worms are threadlike, cylindrical and
creamy white
• Females are 4-10 cm long
• Microfilarial embryos may be seen coiled each in
its own membrane near posterior tip
Filariasis
• Fully grown, shealthed microfilariae are 130-320
microns long
• Adult worms live in lymphatic system producing
microfilariae
• An intermediate host is needed fror further
development of parasite
• Endemic in Africa, India, South China, Japan,
Samoa, Taiwan
• Occurs also in West Indies and Costa Rica
• In Malaya, Ceylon, Indonesia, China, and Korea
there is Malayan filariasis caused by B. malayi
• B. timori is restricted to eastern Indonesian
archipelago
Filariasis
• W. bancrofti or B. malayi has been known in India
since the sixth century BC.
• Estimated that 250 million people are infected
with these parasites
• Infestation often is asymptomatic
• Elephantiasis usually occurs only if hundreds of
thousands of mosquito bites are suffered over a
period of yrs- with episodes of intercurrent
streptococcal lymphangitis
Filariasis
• There is a striking periodicity to time of
appearance and disappearance of
microfilariae in skin and superficial vessels
• Cutex fatigans bites at night
• Microfilariae of W. bancrofti are found in
peripheral circulation at midnight (nocturnal
periodicity) but rarely during daytime
• In South Pacific, it is nonperiodic
Filariasis
• Search for microfilariae should be made on fresh
cover-slip films of blood from finger or ear and
examined with a low-power objective lens
• Specimens should be taken at midnight
• Calcified adult worms may be seen on x-ray
• Adult filariae are found in abscesses or in material
taken for path exam
• Filarial worm can be traced fluorescently as
microfilariae and adult worms have an affinity for
tetracyclines, which fluoresce in UV light in a
dark room
• Filarial complement fixation tests are useful in
seeking the cause of lymphedema
• Prognosis is good
• Living may become burdensome unless condition
is alleviated
• Ivermectin, 100- 440 micrograms/kg in one
dose=TOC
• Regimen (as well as alternative tx with
diethylcarbamzine) will clear microfilariae but not
adult worms
• Surgical operations have been developed to
remove edematous subcutaneous tissue from
scrotum and breast
• Prophylactic measures consist of appropriate
mosquito control; diethylcarbamazine has been
effective in mass prophylaxis