Tissue Nematodes - Cal Flashcards
Trichinella spiralis mode of infection?
Ingestion of undercooked meat
Trichinella spiralis infective stage?
Encysted larva
As adults in the intestine, trichinella can cause mild to severe diarrhea.
However, larval migration can lead to ____, causing allergic rxns (potentially fatal)
eisinophilia
Trichinella can become encysted in striated muscle, causing?
Rheumatoid pain
Toxic reaction
Trichinella can be fatal if?
Toxemia, pneumonitis, myocardial failure, or trichinous encephalitis
Infective third stage larvae encyst in striated muscle.
Non-striated muscle and other tissues do not support development to third stage larvae
Watery diarrhea, vomiting, abdominal discomfort, nausea during ___ of trichinella infection
enteral phase
Facial and ____ edema, fever, weakness, malaise, myalgia, urticarial rash, conjunctivitis and conjunctival and subungual hemorrhages appear during systemic phase (larvae disseminate) of trichinella infection
periorbital
Pts with high trichinella infection burden may die of?
myocarditis, encephalitis, or pneumonia
Chronic cases experience muscle pain
Consider Trichinosis in patients presenting with myositis, eosinophilia (what percentage?), fever, elevated creatine phosphokinase and lactate dehydrogenase
40-50%
Trichinella specimen of choice?
Muscle biopsy
Larvae in striated muscle Surrounded by a longitudinal capsule
Trichinella Found in undercooked pork and game meats where?
worldwide
Larvae migrate to striated muscles (severe phase) edema, eosinophilia, myositis, death can occur
Larvae survive in “nurse cells” for about 6 years.
Diagnosis: history, clinical signs, muscle biopsy
Adults in small intestine mating and depositing larvae (mild phase)
Trichinella
Common name: Guinea worm
Dracunculus medinensis
Female migration: Severe allergenic reactions
Toxemia: As the female reaches the surface of the body
Dracunculus medinensis
Dracunculus medinensis results in blisters where?
Usually lower extremities, with severe itching/burning prior to blister rupture
Dracunculus medinensis infective stage?
Larva undergoes molt in copepod to become an L3 larva
Dracunculus medinensis specimen processing?
Removal of the adult by the twist-stick method
Dracunculus medinensis geography?
Africa, Asia (India)
Acquired by ingesting an infected copepod, usually in water.
Larvae penetrate into humans deep connective tissue, mate, then migrate to subcutaneous tissues.
Dracunculus medinensis
Lymphatic filariasis?
Wucheria bancrofti
Brugia malayi
Mainly blood/lymphatic organisms.
Generally transmitted via bites from flies/mosquitoes
Wucheria bancrofti
Brugia malayi
Once in blood, go to target sites and mature at those locations, causing symptoms
Symptoms include inflammation and swelling due to edema or blockage of vessels
Wucheria bancrofti
Brugia malayi
(most are tropical diseases)
INfective stage of wucheria bancrofti?
And Brugia malayi?
mosquito takes a blood meal, allowing L3 larval to enter host skin
Host habitat for wucheria bancrofti?
Lymphatic
Infective form: Filariform larva
Mode of infection: Inoculation
wucheria bancrofti
Common name: Elephantiasis worm
wucheria bancrofti
Brugia malayi
Pathogenesis: Elephantiasis, fibrosis, thrombi, lymphatic inflammation, granulomatous infiltration
wucheria bancrofti
Often asymptomatic. Often noticed as acute adenolymphangitis with fever and swelling of the leg, arm, or male genitalia but Chronic swelling of the legs and compromised lymphatic drainage may result in secondary bacterial infections and sclerosis and verrucous changes of the overlying skin
wucheria bancrofti
History is important. Exposure to mosquitoes in endemic areas
Microscopic examination of thick and thin blood smears. Best obtained at night.
DIURNAL
wucheria bancrofti
Consider these to be similar enough to W. bancrofti for treatment purposes…
Except this is found more in the Orient
Brugia malayi
Found in Africa, India, SE Asia, South America W. bancrofti is most prevalent,
B. malayi in isolated pockets of?
SE Asia
Adults in lymphatics, microfilariae in blood vessels around the lungs or peripheral areas.
Symptoms: from adult worms, lymphangitis, lymphadenitis, can lead to elephantiasis
Diagnosis: Blood test for microfilariae
B. malayi
W. bancrofti
Lymphatic filiarisis
Common name: Eyeworm
Loa loa
Pathogenesis: Calabar swelling, urticaria, fever, neurologic symptoms, allergenic responses, irritation and destruction of ocular tissues
Loa loa
Calabar swelling?
Loa loa
Habitat: The subcutaneous and deep connective tissue
Loa loa
Tabanid fly, chrysops fly
mango fly
Loa loa
Reservoir host for loa loa?
monkey
Infective form for Loa Loa
filariform
Diagnostic stage of loa loa?
Sheathed microfilariae found in spinal fluid, urine, sputum
Most persons are asymptomatic. Transient Calabar swellings are noted in some
Renal complications (hematuria, proteinuria) and encephalitis may be noted after treatment with diethylcarbamazine
Loa loa
AKA the African Eye Worm
Central and W Africa.
Loa loa
No Wolbachia symbiont
Loa loa
Common name: Blinding filariasis; river blindness
Onchocerca volvulus
Onchocerca volvulus infective stage?
L3 larva from bite of blackfly
Onchocerca volvulus intermediate host?
Blackfly (buffalo gnat)
Adults live in subcutaneous nodules
Pathology is the host’s inflammatory response to the microfilariae
In the eye, microfilariae initially elicit punctate keratitis which can progress to a sclerosing keratitis and blindness
Onchocerca volvulus
may cause inguinal lymph node fibrosis and atrophy of overlying skin that leads to hanging groin
Onchocerca volvulus
Geographical distribution of Onchocerca volvulus
Central and northern South America and Africa
Symptoms: Nodules on head (SA), lower trunk (Africa), pruritic skin reactions, “leopard skin”, hanging groin, progressive blindness
Onchocerca volvulus
Actually a symptom of larval movement in tissues.
Visceral/Cutaneous Larval Migrans
will occur in gut tissues, caused by several species, of which Toxocara spp. are best known
Visceral Larval Migrans
occurs under skin (often termed “creeping eruption”) and many species of worms may cause this (e.g. Ascaris spp. and various hookworms)
CutaneousLarval Migrans
Caused by Toxocara canis and Toxocara cati
Ingestion of infective eggs is the root cause of the problem
Visceral Larval Migrans
Found wherever dogs and cats are found
Puppies can be infected via transplacentally or through breast milk
Visceral Larval Migrans
Toxocara canis infective stage?
embryonated egg
Usually in children < 6 years old
Most have generalized symptoms such as cough, fever, and wheezing
Liver frequently involved, hepatomegaly is common
Lungs, spleen, skin are other sites involved
Toxocara canis
“leopard skin”
O. volvulus
Larval forms leave focal site and migrate through tissues to new sites to mature
Visceral Larval Migrans
Diagnosis is definitively confirmed by finding larvae in affected tissue by histologic examination
Toxocara
Sites characterized by inflammation, damage, and pruritic skin lesions
Long term/deeper infections may have allergic conditions and toxemia reactions
Cutaneous Larval Migrans
Organisms may form granulomas in tissues
Cutaneous Larval Migrans
“Creeping Eruption”
Cutaneous Larval Migrans
