Roundworms And Medically Important Arthropods Flashcards
What are the characteristics of roundworms?
Male and female sexes Complete GI tract (mouth and anus) Diseases caused: Perianal pruritus Inflammatory reaction Pneumonitis Anemia Damage due to movement
What are the characteristics of Enterobius vermicularis?
Also called pinworms
Worlwide distribution
Most common helminthic infection in the USA
Humans are the only host
Ingestion, inhalation of eggs( fecal-oral)
Female lay eggs in perianal area at night
Autoinfection due to larvae crawling back in
Causes enterobiasis
What are the characteristics of enterobiasis?
Perianal itch Perianal pruritus Genitourinary granulomas Associated with Dientamoeba fragilis infections ID: scotch tape mount for pinworm eggs
What are the characteristics of Ascaris lumbricoides?
The most common helminthic infection worldwide
Pathway: intestine-blood- lung- intestine
Most common cause of parasitic infection of bile duct
ID: Knobby eggs in feces
Eggs or adults in feces
Larvae in sputum
What are the diseases caused by Ascaris lumbricoides?
Asymptomatic
Pneumonitis
Loeffler syndrome
Perforation of intestine and other organs
Intestinal blockage
Distension of small and large bowel with air fluid levels
may enter bile uct ansd cause biliary colic,gallstone formation,liver abscess
What are the characrteristics of Toxocara canis, Toxocara cati, Baylisascaris procyonis?
Ascarids of dogs, cats and raccoons respectively
T. Canis and T. Cati have visceral and ocular larva migrans
B. Procyonis have neural larva migrans
ID: clinical picture, eosinophilia, ELISA/serology
What are the charactreristics of Trichuris trichiura?
Also called Whipworm Humans are the only host Diseases caused : Asymptomatic Bloody diarrhea Appendicitis Rectal prolapse ID: barrel shaped eggs
What are the characteristics of Trichinella spiralis?
Infection from ingestion of cysts in undercooked pork, walrus and bear
Larvae migrate to striated muscle
larvae live years, eventually cysts calcify
Cause trichinosis, trichinellosis-
What are the characteristics of trichinellosis?
Asymptomatic to lethal depending on worm burden
Deadly triad: myocarditis, encephalitis, pneumonitis
death within 4-6 weeks
ID: Splinter hemorrhages, microscopy of meat, serological tests
What are the characteristics of Necator americanus and Ancylostoma duodenale?
Respectively called New World and Old World hookworms
Infection by penetration of skin by filariform larvae
Adults attach to intestinal wall with chitinous plates (N. Americanus), and teeth (A. Duodenale)
What are the diseases caused by N. americanus and A.duodenale?
Pruritus at skin site Diarrhea Pneumonitis Microcytic anemia Emaciation Physical and mental retardation from nutritional deficiency ID: eggs in feces
What are the characteristics of Ancylostoma braziliense?
Dog and cat hookworm
Fecal contaminated beaches (SE USA)
Cutaneous larva migrans- pruritus, «serpiginous or creeping eruption» lesions of 3 weeks duration
Humans are dead end hosts
What are the characteristics of Strongyloides stercoralis?
Threadworm similar to hookworm Domestic pets are reservoirs Filarifrom larvae penetrate skin Pathway: Skin-blood-lung-intestine Autoinfection possible In the intestine female can reproduce by parthogenesis
What are the diseases caused by Strongyloides stercoralis?
Ground itch/creeping eruption
Pneumonitis
Asymptomatic to peptic ulcer like disease
Chronic infections can last years
86% fatality in IC patients with disseminated disease (hyperinfection)
ID: Baermann funnel gauze method to concentrate larvae from feces
Larvae in fecal smears, eggs are rare
What are the filarid parasites?
Wuchereria bancrofti and Brugia malaya
Loa loa
Onchocerca volvulus
All found in tropical and subtropical regions
ID: eosinophilia, microfilaria in Giemsa stained blood smears or tissue preps
What are the Characteristics of Wuchereria bancrofti?
The mosquitoes are vectors
causes elephantiasis which is due to clogging of the lymphatic vessels by microfilaria
Occur 9-12 months post bite
What are the characteristic of loiasis?
Occurs in Central Africa
Introduced by a bite of the mango fly, deer fly or horsefly
Worms mature and migrate for as much as 17 years
Causes Loiasis of eye
Calabar skin swellings: transient large nodular, painful, pruritic swellings in the extremities caused by worm migration
What are the characteristics of Onchocerca volvulus?
The female blackfly is the vector
Causes river blindness
Acute and chronic inflammation involving many tissues but most notably the eyes, hyperpigmented skin
What are the characteristics of Latrodectism mactans?
Caused Latrodectus mactans or black widow bite
Painful bite
Symptoms appear 40 minutes after a bite
Pain and abdominal stiffness
Erythema or pain at the site of the bite, thoracic pain
Pain in extremities and contractures
Psychomotor alterations
Relief within 24 hours
DX: difficult without clear history of spider bite
What are the characteristics of Loxoscelism?
Caused by bite by Loxosceles reclusa or brown recluse spider
Less painful bite compare to black widow bite
Mild local urticarial (hive like) reactions to full thickness skin necrosis in 3-4 days
Location: hands, arms and lower extremities
Other symptoms: fever headache, malaise. Joint aches, nausea and vomiting
Widely distributed in the southeast USA and Midwest in outdoors and basements
What are the toxins in scorpions?
Neurotoxin
Hemorrhagic/hemolytic toxin-pain swelling, necrosis
Death can result from pulmonary edema or respiratory paralysis
Horse antivenin available
Possibility of serum sickness
What are the characteristics of Sarcoptes scabiei?
Causes by scabies, mange, itch mite
Also an STD
Transmitted through close contact and fomites
ID: ova and mites present in skin scrapings treated with 20% KOH
For confirmation must find Scybala: barrel shaped brown fecal pellet on a skin scraping of a burrow
What are the chracteristics of Trombiculiasis?
Caused by Trombicula irritans, Eutrombicula or Chigger bites
Chiggers bite and suck fluids
Larvae mites have 3 pairs of legs and adults have 4
What are the characteristics of Myiasis causing flies?
Caused maggots in nasal,intestinal,urinary or dermal tissue
Larvae develop over 40-50 days causes warble lesion
Secondary infections, abscesses when larvae die
What are the characteristics of pediculosis,Phthiriasis?
Caused by Pediculus,Phthrius- lice have 3 types: Pediculus humanus capitis predominantly on the scalp may involve other facial hair and mainly in children Pediculus humanus corporis- body Phthrius pubis-pubic crabs
What are the characteristics of Pulex, Ctenocephalides?
Fleas dont normally reside on humans
Close contact with animals
Siphonaptera
Vector for D.caninum, plague and murine typhus
What are the characteristics of Cimex?
Bed bugs due to crowded, poor hygiene Bugs, eggs, fecal droppings in bedding Bites occur at night Erythematous bites Locations: face, neck, hands or arms
