Helminth Diseases (Exam 2) Flashcards
three classes of parasites that cause disease in humans
protozoa, helminths, ectoparasites
transmission of helminth diseases
- food and water, vectors, direct contact
- prevalent in tropical countries
- developing countries => 90% have at least one worm
- presence in U.S. is of increasing concern because of immigration, travel, HIV (physicians here are unable to recognize helminth diseases)
classification of Helminths
- flat worms (Digenian flukes)
- tapeworms (cestodes)
- round worms (nematodes)
types of fluke diseases
- schistosomiasis (bilharzia)
- opisthorchis sinensis (chinese liver fluke)
- paragonimus sp. (lung fluke)
- echinostome (human fluke)
what is the 2nd nastiest parasitic infection?
schistomiasis
schistosomiasis (symptoms)
- itchiness; damage to liver, intestine, bladder
- rarely, eggs move to brain and spinal cord => seizures and paralysis
- coughing up blood (oesophagogastic)
What helminth disease is called ‘Katayama’ fever?
Acute schistosomiasis
What sickness does acute schistosomiasis represent? What are the symptoms and how long do they last?
Resembles ‘serum sickness’ (immune disease)
Symptoms: often asymptomatic or flu-like; last weeks to months
What happens with chronic intestinal schistosomiasis?
eggs get trapped in liver –> fibrosis
affects intestines (severe)
symptoms seen years after infection
granulomatous inflammation around eggs
chronic hepatosplenic schistosomiasis
how to diagnose?
similar to chronic intestinal schistosomiasis
diagnosis: biopsy of liver to see cellular granulomas that occur at block blood flow
what disease normally infects birds or small mammals and is not capable of fully developing in man?
swimmer’s itch (cercarial dermatitis)
how is schistosomiasis diagnosed?
- finding eggs in urine or stool; must be tested on multiple days
- serum testing for antibodies -> must wait 6-8 week post infection
what is the third most prevalent worm parasite in the world and endemic in Asia?
Opisthorchis Sinensis
what type of helminth is opisthorchis sinensis?
flat worm (chinese liver fluke)
what helminth is capable of causing cancer?
opisthorchis sinensis
how is opisthorchis sinensis diagnosed?
identification of eggs in stool specimen with microscope
what is the portal of entry and exit for opisthorchis sinensis?
entry: ingest raw or undercooked fish
exit: feces
what helminth feeds on bile?
opisthorchis sinensis (chinese liver fluke)
which helminth disease has an intermediate host of >54 species of freshwater snails?
Paragonimus (infectious lung fluke endemic in Asia)
Which helminth disease has an intermediate host of 1 species of freshwater snail?
schistosomiasis
what are the symptoms for long-term infections of paragonimus?
mimics bronchitis or TB
How is Taeniasis transmitted?
humans pass tapeworm segments/eggs in feces and contaminate soil -> cows and pigs infected when eating -> humans become infected from eating beef or pork
Rare in U.S. unless there is poor sanitation
what disease can Taenia eggs cause in animals and how?
eggs in animal’s intestine hatch and migrate to striated muscle, causing cysticercosis
what helminth disease causes gradual weight loss that is not noticeable?
Taeniasis
what are the tapeworm species that cause Taeniasis? which causes the most symptoms and why?
beef, pork (T. solium), asian (T. asiatica)
beef (T. saginata) causes the most symptoms because it is larger in size (up to 10 m; the other two tapeworms are about 3 m)
which helminth disease has the visible sign of segments of worm in feces?
taeniasis
what causes cysticercosis? what parts of the body are infected and what is the result?
Cysticercosis is caused by larval cysts of T. soleum (pork tapeworm). The cysts infect the brain, muscle, tissue and cause seizures
what contains testes and uterus?
tapeworms
what is the largest parasite that infects humans?
fish tapeworm (Diphyllobothrium latum)
what is the portal of entry and exit for fish tapeworm?
entry: eating raw or undercooked fish that contain cysts
exit: stool (larvae grown in 3-6 weeks up to 30 feet)
what are the roundworms?
- Enterobius (pinworms)
- Ascaris Lumbricoides
- Trichinellosis
- Trichuris Trichuria (tapeworms) and hookworms
- lympathic filariasis (Elephatiasis)
- onchocera volvulus (river blindness)
- dracanculus medinensis (guinea worm)
what roundworm lays eggs at night time that causes intense itching and nightmares?
pinworms
Very infectious!
what is the most common helminthic disease in the U.S.?
Enterobius vermicularis (pinworm disease)
how is enterobiasis transmitted?
direct contact with eggs on people, sheets, or inhalation of airborne eggs
how is enterobiasis diagnosed?
scotch tape test
who is commonly effected by pinworms?
children, institutionalized
what is the most common human worm infection? (surveillance)
Ascaris Lumbricoides
infects 25% of world population (tropics)
50% of children in U.S.
while many are asymptomatic, what are other potential symptoms of Ascaris Lumbricoides?
- damage to lungs (COUGH)
- severe: malnutrition
- intestinal obstruction -> death
what type of transmission is Ascaris Lumbricoides?
fecal-oral; can also cough out worms
chemo can be used to treat what?
roundworms
what causes trichinellosis?
trichinella spiralis
what disease is obtained from eating raw or undercooked pork or wild game infected with cysts?
trichinellosis
digestive juices dissolve the hard covering of ingested cysts and emerge in intestine in which disease?
trichinellosis
which disease is not typically transmitted by humans?
trichinellosis
animals (major reservoirs) feed upon infected rodents
Trichinellosis often presents as flu-like symptoms. What other more severe symptom presents itself and how is it diagnosed?
Larvae deposit into muscle. Diagnosis: muscle biopsy and blood test
What heavy infection symptoms occur from being infected with hookworms/whipworms?
painful stool that contains mucus, water, and blood. rectal prolapse. mental retardation in children.
what disease is transmitted by walking barefoot on soil that is contaminated with feces?
whipworm/hookworm (penetrates skin)
Other than flu-like symptoms, what is another first sign of infection of hookworms/whipworms? What other effect can occur?
- itching
- physical and cognitive growth of children affected (due to malnutrition)
what disease is spread through mosquitos?
Lymphatic filariasis (elephantiasis)
what helminth disease has hope for global eradication?
lymphatic filariasis
what disease has an effective single dose treatment available?
lymphatic filariasis
what disease is spread by bites of blackflies?
onchocerca volvulus (larvae develop in 10-12 days)
what are the symptoms of onchocerca volvulus?
- live under the skin and near muscles and joints, causing significant pain
- thickening of cornea => “River Blindness”
which disease is referred to as “river blindness”?
onchocerca volvulus
what does the guinea worm cause?
Dracanulus medinensis
what is the portal of entry and exit for dracanulus medinensis?
entry: drinking contaminated water
exit: blister develops -> cool water to ease burning pain -> worm detects temperature change and bursts from blister
what is the portal of entry and exit for schistomiasis?
- portal of entry: cercarieae penetrate skin of bathers -> migrate to blood vessels (worms feed on blood) -> invade liver
- portal of exit: eggs discharged in feces and urine -> develop into Cercariae
- male and female worms stay together for life cycle
- infection for years
