Parasitology III-IV Flashcards
What is the severity of symptoms of the helminths infection related to?
The number of organisms at inoculation because they do not multiply within the human host
What are the only helminths that reproduce in humans?
- Strongyloides
- Hymenolepsis nana
What are the nematodes that are acquired by passage though the skin?
- Strongyloides stercoralis
- Hookworms
What is the movement of Strongyloides though the body?
Penetration through the skin is followed by relocation to the lungs and ends up in the intestines
Why is Strongyloides a chronic infection?
Due to its ability for autoinfection
How is Strongyloides diagnosed?
- Marked eosinophilia
- Rhabditiform larvae in stool
What is the treatment for Strongyloides?
Albedazole
What are the species of hookworm?
Ancylostoma duodonale
Necator americanus
What is the difference in the life cycle of hookworms and Strongyloides?
Ova passed in feces - hatches to R. larva in soil whereas Strongyloides can pass larvae in the stool
What are some symptoms of the hookworm infection?
Iron deficiency anemia
How are hookworms diagnosed?
Ova found in feces with microcytic anemia
What is the treatment for hookworms?
Albendazole
What are the nematodes acquired by ingestion?
Visceral/Ocular/Neural Larva Migrans
- Ascaris lumbricoides
- Toxocara canis, Toxocara catis
- Baylisascaris procyonis
How is Ascaris lumbricoides diagnosed?
- Ova/worm in the stool
- Barium x-ray
What is the treatment for Ascaris?
Albendazole
What are the nematodes that humans are accidental hosts for?
- Toxocara canis, Toxocara catis
- Baylisascaris procyonis
What are the signs of V/O/N larva migrans?
Wandering larvae produce hemorrhage and inflammation – Eosinophilic infiltration, granulomas - humans are not the right host so worms cannot embed like in their normal host
How are visceral larvae migrans diagnosed?
- Larva in tissue
- Serology
What is the treatment for visceral larvae migrans?
Albendazole - none effective for Balylisascariasis
What is the life cycle of Enterobius vermicularis (pinworm)?
Ova are ingested and it develops in the intestine where the female migrates to the perianal region to deposit eggs
What are the signs of pinworm infection?
- Perianal and perineal itching
* GU granuloma
How is pinworm infection diagnosed?
Ova demonstrated on tape from perianal area
What is the treatment for pinworms?
Albendazole - there is reinfection possibility though so MUST TREAT TWICE
Where is Trichuris tirchiura infection commonly seen in the world?
In the tropics
What is the life cycle of Trichuris tirchiura?
Ingested ova will develop only within the intestine
What are the signs of Trichuris tirchiura infection?
Most are asymptomatic but serious infections can have: – Diarrhea – Abdominal pain – Rectal prolapse – Anemia
How is Trichuris tirchiura diagnosed?
Ova in feces with morphology of polar plugs
What is the treatment for Trichuris tirchiura?
Albendazole
What is the life cycle of Trichinella spiralis?
Infects carnivorous animals like rats, swine and bears and is acquired by ingestion of undercooked meat - enters the skeletal muscle
What are the phases of trichinosis?
Phase I - diarrheal intestinal phase
Phase II - migration of larvae to the muscle causing pain - often in the muscles around the eyes
Phase III - recovery
How is trichinosis diagnosed?
- Eosinophilia with elevated muscle enzymes
- Serology
- Muscle biopsy
What is the treatment for trichinosis?
Albendazole - role of drug is to eliminate the adult form
What is the cause of eosinophilic meningitis?
Angiostrongylus cantonensis
How is eosinophilic meningitis acquired?
Ingestion of snail or snail secretions
How is eosinophilic meningitis diagnosed?
Eosinophils and larvae in CSF
What is the life cycle of lymphatic filariasis organisms?
– Larvae transmitted by several mosquito types
– Adults in lymphatics produce larvae which circulate in bloodstream
What are the manifestations of lymphatic filariasis?
• Acute - lymphangitis and lymphadenitis
– Nocturnal cough and wheezing
• Chronic - lymphatic destruction
– Obstruction and chronic lymphedema
How is lymphatic filariasis diagnosed?
– Eosinophilia
– Bloodsmears
How is lymphatic filariasis treated?
– Diethylcarbamazine/Doxycylcine
What is the vector of Onchocerciasis?
Black fly Simulium - inoculates onchocerca larvae
What are the symptoms of onchocerciasis due to?
Dead or dying microfilariae
What is one possible result of Onchocerciasis?
Blindness if the parasite migrates to the eye - keratitis in the lens is one example
How is onchocerciasis diagnosed?
– Biopsy
– Skin snips
- Serology
What is the treatment for onchocerciasis?
Ivermectin
What is the vector of Loa loa?
Tabanid fly Chrysops
What are that manifestations of Loa loa infection?
- Painful Calabar swellings
- Worm in conjunctiva
How is Loa loa diagnosed?
– Microfilariae in blood smear
– Adult in subcutaneous nodule or eye
Whati s the treatment for Loa loa?
Diethylcarbamazine
How is Dracunculus medinensis (Guinea worm) acquired?
Ingestion of copepod containing water from wells - larvae will migrate into tissue
What are some characteristic of Guinea worm infection?
Blisters with chronic non-healing sores - typically on the lower extremities
How is Guinea worm treated?
See worm in skin or with X-ray
What is used to treat Guinea worm?
Metronidazole
What is Taenia saginata known as?
Beef tapeworm
What is Taenia solium known as?
Pork tapeworm
What Diphyllobothrium latum known as?
Fish tapeworm
What is Hymenolepsis nana known as?
Dwarf tapeworm
What is a defining characteristic of Hymenolepsis?
Autoinfection - can lead to enteritis
Cysticercosis
Infection with larval form of T.solium after ingestion of ova from human feces leading to cerebral effects:
– Meningoencephalitis and hydrocephalus
– Space occupying lesions
– Seizures
How are tapeworm infections diagnosed?
Ova or proglottids in the feces or MRI/X-ray with cystercercosis
What is the treatment for tapeworms?
Praziquantel
What is the treatment for cystercercosis?
Albendazole
What deficiency can occur with D. latum infection?
Vitamin B12 deficiency
What is Echinococcus granulosis known as?
Dog tapeworm
What is the sylvatic form of the dog tapeworm?
E. multiocularis
What are the clinical signs of E. granulosis?
Space occupying lesion in liver, lung, kidney, bone
What are the clinical signs of E. multilocularis?
Spreads like a malignancy
What is the difficulty in treatment of the dog tapeworm?
Surgical removal of the cyst but it is difficult to not break open the contents
What is the life cycle of Schistosoma?
Complex life cycle that involves snails and can invade through the skin of humans wading in water where they will invade in the liver to reproduce
Katayama Fever
Associated with Schistosoma infection with acute fever, cough and LAD that is self-limiting
How is Schistosomiasis diagnosed?
– Characteristic ova in feces or urine
– Rectal biopsy crush preparation
What is the treatment for Schistosomiasis?
Praziquantel
What does S. mansoni ova have as characteristics?
Round with a distinguishing spine
Cercarial Dermatitis
- Accidental infection of human swimmers with duck schistosome
- Papular dermatitis with intense itching
What are some of the associations of Clonorchis (liver fluke) infection?
– Obstructive biliary tract disease
– Associated with cholangiocarcinoma
How is Clonorchis acquired?
- Complex life cycle involving snail
* Acquired by ingestion of metacercariae- infested fish
What are the signs of Paragonimus westermani (lung fluke) infection?
Cough, hemoptysis, chronic pneumonia, lung abscess, pleural empyema
How is Paragonimus acquired?
- Complex life cycle involving snail
* Acquired by ingestion of metecercaraial- infested crayfish/crab
How is Paragonimus diagnosed?
Ova seen in the sputum or in the stool