Parasitic infections : helminths and arthopods

Question 1

What are the types of helminths?

Answer 1

Flukes, tapeworms and roundworms. These are all parasitic worms

Question 2

What are cestodes?

Answer 2

Tapeworms such as echonosia granulosa and taenia spp.

Question 3

What are trematodes?

Answer 3

Flukes such as schistosoma and fasicola hepatica

Question 4

What are nematodes?

Answer 4

Roundworms such as ascaris

Question 5

What is a larval cyst?

Answer 5

Young and inactive tapeworm

Question 6

How are helminths transmitted?

Answer 6

Infection by larvae or eggs present on surfaces or contaminated food which cause pathology and have tortuous (bendy) migration in the host. Adults cannot replicate.

Question 7

What is a characterisitic marker of helminth infection?

Answer 7

Eosinophilia (high levels of eosinophils in the blood

Question 8

What are soil-transmitted helminths?

Answer 8

Contamination of soil with the faeces containing larvae of an infected person
Roundworm: ascariasis
Whipworm: trichuris
Hookworm: necator or anclostoma

Question 9

How does whipworm infiltrate the GI tract?

Answer 9

Trichuris larvae directly enter the GI tract

Question 10

How does roundworm infiltrate the GI tract?

Answer 10

Ascariasis larvae travels via blood -> heart -> lungs -> intestines

Question 11

How does hookworm infiltrate the GI tract?

Answer 11

Necator/anclostoma larvae travels via blood -> heart -> lungs -> intestines

Question 12

What are the manifestations of soil-transmitted helminths?

Answer 12

At low levels of infection, asymptomatic, Can lead to abdominal pain, diarrhoea. Worms feed on blood and protein leading to loss and anaemia and muscle wasting and rectal prolapse. There is impaired uptake of glucose

Question 13

How are soil-transmitted helminths treated?

Answer 13

Deworming medication which disrupts the microtubular integrity by inhibiting tubulin polymerisation. This prevents motility and replication

Question 14

How is ascariasis transmitted?

Answer 14

Nematode (roundworm) via faeco-oral transmission of eggs. It hatches when swallowed and invades intestinal mucosa to enter the lungs where it matures and ascend up the pharynx to be swallowed. This gives it access to the lumen of the small intestine for up to 2 years to cause intestinal illness.

Question 15

What happens following ascarasis transmission?

Answer 15

Invades intestinal mucosa to enter portal circulation and reach the systemic circulation of the lungs. Matures in the lungs and penetrates the alveolar walls to ascend the bronchial tree and be swallowed to travel into the small intestine. Larvae are released in the faeces and become embryonate (infective). They hatch when swallowed.

Question 16

What is taeniasis?

Answer 16

Cestode parasitic infection caused by the ingestion of larval cysts of the tapeworm. Species are classified based on the cattle affected such as beef and pork that has grazed on infected vegetation.

Question 17

What is the host for Athenians is?

Answer 17

Pigs.

Question 18

What is the mechanism of taeniasis?

Answer 18

Larval cysts are ingested and develops from oncospheres -> cysterni in muscle and hatches to penetrate intestinal walls. It matures into adult form in the large intestine. Asymptomatic but causes weight loss and constipation and diarrhoea.

Question 19

What is cysticercosis?

Answer 19

Parasitic tissue infection caused by larval cysts of the taenia solium tapeworm due to the ingestion of eggs which mature into larvae that migrate to the different organs, including the brain and major cause of adult seizure

Question 20

What is schistosomiasis?

Answer 20

Parasitic infection caused by a blood fluke which leads to chronic inflammation. It is the leading cause ofdeath by parasitic infection second to malaria. It is transmitted by swimming in free water and snails are an intermediate host.

Question 21

What are the species of schistosomiasis?

Answer 21

Mansoni, hematoboium, and japonicum

Question 22

Which species of schistosomiasis causes intestinal illness?

Answer 22

Mansoni and jeparacium. They can lead to secondary hepatomegaly, splenomegaly and portal hypertension

Question 23

Which species of schistosomiasis infects the urinary bladder?

Answer 23

Hematoboium that can lead to squamous cell carcinoma and pulmonary hypertension

Question 24

What causes manifestation of schistosomiasis?

Answer 24

Eggs derive nutrition from the intestine or the bladder and enter portal circulation in liver to mature into adults where they reside in blood vessels. The ongoing exposure to eggs triggers chronic inflammation in the body and intestinal bleeding and iron-deficiency anaemia

Question 25

Which body systems are affected by schistosomiasis?

Answer 25

Liver, intestines, bladder, lungs which undergo continous damage

Question 26

How is schistosomiasis transmitted?

Answer 26

Swimming in fresh water, and snails are the intermediate host.

Question 27

What is Elephantitis?

Answer 27

Also known as lymphatic filiariasis, it is a parasitic infection caused by the roundworm filiarisis transmitted by mosquito bites which infiltrate and block the lymph nodes, leading to oedema and enlargemnt of the limbs.

Question 28

What is Echinococcus granulosus?

Answer 28

Cestode/tapeworm infection where sheep are the intermediate host with food contaminated with dog faeces and results in Hyatid cysts in the liver.

Question 29

What are the types of filarial roundworms?

Answer 29

Wuchereria bancrofti, brugia malayi, brugia timori. As adults they produce microfilariae

Question 30

What is River Blindness disease?

Answer 30

Caused by the parasite oncherca vervus which breeds near fast flowing water near rivers and is the leading cause of blindness in African countries.

Question 31

What is Hyatid disease?

Answer 31

Caused bycestode tapewoem echnicoccus granulosus. The eggs are present in faeces. They develop into larval cysts in the organs such as the liver and become adults only in a definitive host that are dogs and canines.

Question 32

What is guinea worm disease?

Answer 32

Caused by dracunculus medinensis migrates through the subcutaneous tissue which causes severe pain in the joints.

Question 33

What are arthopods?

Answer 33

Caused by invertebrae that induce disease, includes lice, scabies and fleas

Question 34

What is scabies?

Answer 34

Infestation of the skin by the mite Sarcoptes scabie var hominis which burrows into the epidermis and lays its eggs, causing scaling and vesicles.

Question 35

How is scabies transmitted?

Answer 35

Direct skin-skin contact which causes intense itchinga dn pimple-like rash

Question 36

What are the types of flatworms?

Answer 36

Cestodes and Trematode.

Question 37

Which immune cells are raised in worm conditions?

Answer 37

Eosinophils