Helminth infections Flashcards

1
Q

what are the 3 worm groupings of helmiths

A

Nermatodes (round worms)

trematodes (flukes)

Cestodes (tapeworm

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2
Q

Describe nematode

A

aka roundworm

ascaris, hookworm, whipworm

have a round cross section common morpholoy

distint head whihc cotnaisn mouht

tial

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3
Q

name some trematodes (AKA fukes)

A

flattedn boyd shape can grow to 1-6mm lack a digestive tract

absorb nutrients across there rufrcae

FLukes

liver flukes, blood flukes (schistosomes)

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4
Q

Describe cestodes?

A

tapewomr (hyatids)

cestodes can grwo to extreem lenghts- up to 20m

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5
Q

Describe soil transmission of Helminths (nematodes)

A

ascariris, whipwroms, hookworms

strongyloide stercoralis (threawork or pin worm)- uk association

transmision of soil transmitted occurs via faecl orla-route

6 Fs of worm infections- Faewces, fluids, flies, fileds, finger, food

lack of adeuqat sanitation

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6
Q

Describe ascaris infections

A

ascaris lumbricoid (ascaris)- causativ agent of ascariasisi

largest of the roundworms (nematodes)

up to 35 cm on average

1 billion peoepl every year are infected

maybe responiobel fro 500K deaths a yearr- mainyl in children under 5

  • ingesting food/water contaminated with eggs
  • pass into intestine
  • hatch and release larvae into the gut lumen
  • larave penetrate fut wall and enter ciruclatory system and migrate to lung for further developed
  • dveelop cough and then swallow larvae- furthr maturation in the gut
  • mature worm mate and produc eegegs -expelled in faeces
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7
Q

how does the pathology of ascariasis manifesdt?

A

many asymptomatic

as worm burdne incerease- increase in symptoms (lethargy,weight loss, inability to concnetrate - competeiton for nutreitns with parasite

slow growht in kids

GI symptoms may even get bowel obstruction and intestinal bleeding

the developing larvae spreading to lungs may csaise respiraotry problems- Eosinophillic penumona (lofflers syndrome)

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8
Q

what is the treatment for ascariasis

A

Mebendazole

after stool sample analysi by light microsopcy looking for eggs

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9
Q

descrtibe the epidemiology of hook worms

A

widespread often concurent with ascariasis infections- same codntiomns 6Fs- faciliate dissemination of both

Prescen of ascaris is considered a riks factro for acwuiring hook worm)

ancylosotma doudenale, necator americanus

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10
Q

Describe the life cycle of hook worms

A
  • similart to ascariais lung invovlemdnt- but egg doesnt have tp bne ingested
  • eggs spread into environemnt via open defecation
  • eggs hatch in soil and motile larva chemoattracted to the new host
    • move towards skimn and then burrown
    • larvae enter the skin - migrte to ciruclatory system to lung developmen
    • coughed up swallowed an mature in intestine
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11
Q

what is this?

A

hookworm

as it enters the ksin causes an allergic reacgion a site of parasite pentrating and moving within skin- cutaneous larva migrans

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12
Q

what pathology do hookworms causes?

A

often asymptomatic

has small teeth like projects it sues to attache to the gut- damages the gut wall - cauases blood protieon and gfluid loss- malbasoption, hypoproteinaemai and anaemia

  • manutrtion
  • aneamria
  • cardiasc complications due to blood loos and iron malbasoption
  • severe acute pulmonary reactions (pneumonia) and gastrointestinal reactions
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13
Q

what is a hookworm that is spread by dogs- but cannot enter cirulation

A

Ancylostoma Caninum

not adpated to hmans but can enter the skin and cause cutaneous larva migrans

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14
Q

how do we treat hook worm>

A

detetc eggs in stool by light micoscopy

treatment- Mebendazole

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15
Q

what are trematodes (flukes)

A

tissue rsident helminths

parasitc worms that invade other areas of the body away from the pirmayr infeciton

Schistosoma—-? schiastomiasis (bilhazia)

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16
Q

What is schistosomaiiss (bilharazia)- most causive species and how do they manifest dofferently?

A

make up 85% of cases of bulharzia in africa

  • S.haematobium- urogential/bladder problems
  • S mansoni and S japonicum - cause intestinal and hepatic disease
17
Q

Describe the life cycles of schistosomiasis? what intermediate host is needed

A

s. haematobium, s. mansoni and s japonicium have similar life cyccles

  • require aquatic snail as intermediate host into humans
  • infected human host shed. eggs into environemnt (fresh water)
  • eggs hatch and parasite attached to snail
  • in snails paraiste matures to infectious form and released into water
  • chemoattracted to humans- penetrta skin and enter ciruclatory syste,
  • migrate to live where they develop and mature into final worm stage
    • S.haematobium- venous plexus of bladder—> urien
    • Smansoni/S japonicicum- mesenteric veins of intestine- secret eggs into GI tract- faeces
18
Q

what is this ?

A

swimmer sitch (inflamamtion and itching)- causeed by entry of the skin by the schistosomiasis

19
Q

describe the presentation of S.haematobium

A

urogential schistosomiaiss

haematoutria- firbosis of bladder and ureter

increase risk of squmaous bladder cancr

women- gentila leison, vaginal bleeding, pain during intercourse

men- dmagae to the smeinal vesicle, prostate and othe organs- infertility

20
Q

describe the presentation fo S.mansoni and S.japoncium

A

heptatic-intestinal schistomsosmais

abdominal pain, diarrhoea and blood in the stool

hepatomwgalty, splenomagaly

ascites/oprotal hyper ttension

21
Q

schihistosomiasis treatment?

A

praziquantel taken for 2 days

22
Q

Describe the life cycle of a cestodes (tapeworm)

1.

A

humans can act as intermeidate host (harbours sexually immature parasite) or defintiive parasite

  • humans as definitve host
    • pig or cow intermeidate host- ingest eggs and cust develop in infect anaimla musculature/tissues
    • cyst cotnaining meat ingested by a huma- enters GI tract develops into adult form- shed in faces- ingested by another animal
  • human as the intermeiadt host
    • human ingets eggs - cysts then form inside the human tissues/musculatrure instead of animal- cysticerosis
23
Q

what is cysticercosis? treatment

A

humans ingest eggs of tapeworm (cestodes) and then beocme the itnermeidat host- cyst formation in the body tissues- muscles (cysts can die and calcidied), eyebody, extraocular msucles etc

in severe cases get neurocysticerosis- seirzires headahces, dementia, meningtiis

need treatment- praziquantel or albendazole

24
Q

what are hydatids? what are the 2 major forms of echinocccosis?

A

specialised form of tapeworm- also known as echinoccocccus

humans are the intermediate host

cystic echinococccosis (CE)

alveolar echinococcosis (AE)

25
Q

describe the lifecycle of echinococcus infections

A

normally restricted to animals but accidnrtal expsorue to humans can get in humans

if humans ingets eggs from, contaminetd foost-

human acts as intemeidat host- cysts can from in tissues (CE or AE)

26
Q

describe the pathology of CE cystic echinococcosis

A

hytadi cysts develop in liver and lungs

aymptomatic incubation period of disease cna last for years until the hydatid cyst grows to extent theta they show symptoms

  • liver- abdominal pain, nausa, vommiting
  • lung- shortness of breat, chronic cough, chest pain
27
Q

DEscribe alvoelair echinococcosis (AE)

A

incubation period of 5-15 years and the slow developed of tumour like lesiosn- ususally loacted in the liver

weight loss, adbdominal pain, geenral maise, hepatic fialure signs

28
Q

what is the treatment for hydatid infections CE/AE

A

diagnosis with ultraosonogrpahy/contrast enchan cde MRI

CE- mamnaged with albendazole/mebednazole- surgery to remvoe cysts- but dnagerous if cysts burst- trigger anaphyalxis/ caus deaht

AE- much more difficutlt o treta- surgery

29
Q

How does Mebendazole work? what would it be used for? side effects

A

round words

Mebendazole- inhibits synthesis of microtubules blocker polymerization of tubulion in parasites intestianal cells/ cant uptake glucose sos die

side effects- target eukarotyci cell processes- nausea, and others, alopeia, dizziness, skinr eactiosn- contraindiacted in pregnancy, netorpenia, seizure

30
Q

what is Niclosamide used for? and how does it work

A
  • used for tape worms
  • niclosamdie- blocks glucose uptake, oxidative phosporylation and anaeorbic metbaolics of intestinal tapeworm
31
Q

how does praziquantel work and what is it used for?

A

used agasint schistomsomaisis (bilharzia)

praziquantel- paralsyss adult worms and larvae

may cause nasua, ehadahce, dizizness, single does