Week 9: Digestive system (viral and protozoal)

Question 1

Which virus is responsible for 90% of viral gastroenteritis

Answer 1

Rotavirus

Question 2

Paramyxovirus causes what viral disease

Answer 2

Mumps

Question 3

What manifestations are seen in mumps

Answer 3

Inflammation and swelling of parotid (salivary) glands unilaterally, fever, pain

Question 4

How is mumps transmitted

Answer 4

Saliva and respiratory secretions, via respiratory tract

Question 5

What vaccine is used for mumps

Answer 5

MMR live attenuated vaccine

Question 6

Which virus is the cause of cytomegalovirus inclusion disease

Answer 6

Herpes HSV5

Question 7

Mechanism of viral inclusion in cytomegalovirus inclusion disease

Answer 7

HV5 incorporated into cell, causing nuclear inclusion and enlarged cell with viral inclusion body

Question 8

Are antibodies effective in cytomegalovirus inclusion disease

Answer 8

No, antibodies are formed but fail to clear virus

Question 9

What is the relevance of cytomegalovirus inclusion disease to pregnant women

Answer 9

Non immune pregnant women transfer the virus to the fetus, causing death or severe damage

Question 10

How many viruses are capable of causing viral hepatitis

Answer 10

6

Question 11

Causative agent of ergot poisoning

Answer 11

Mycotoxin of Claviceps purpeura (fungus)

Question 12

How does Claviceps purpeura cause disease

Answer 12

The fungus causes smut infection on grain crops. Ingestion of grains contaminated with the fungus cause ergot poisoning with hallucinogenic symptoms

Question 13

Aflatoxin causative agent

Answer 13

Mycotoxin of Asperguilus flavus

Question 14

Asperguilus flavus is found on what and causes what

Answer 14

Peanuts and other foods, causing Aflatoxin poisoning and cirrhosis of the liver

Question 15

6 protozoal diseases of digestive tract

Answer 15

Cryptosporidium, giardia, amoebic dysentry, helminthic diseases, nematode infections

Question 16

Compare cryptosporidium parvum genotypes 1 and 2

Answer 16

Genotype 1 affects humans and is also known as C. hominis, genotype 2 affects humans and animals

Question 17

How is cryptosporidium parvum/hominis transmitted

Answer 17

Faecal oral route from water contamination

Question 18

What staining techniques are used to identify C. parvum?

Answer 18

Methyl green acts as a background for oocysts which do not stain, or oocysts can be stained using modified acid fast technique

Can also be stained using antibody staining or FISH

Question 19

Can chlorine be used to eliminate oocysts of C. parvum?

Answer 19

No they are resistant to chlorine

Question 20

What is the difference between platyhelminths and nematodes

Answer 20

Nematodes are round worms, platyhelminths are flat worms

Question 21

What is a scolex in relation to tape worms?

Answer 21

The head region which has suckers

Question 22

How do tape worms get nutrition?

Answer 22

Lack digestive system, so absorb food digested by human host through cuticle

Question 23

What are proglottids in relation to tapeworms?

Answer 23

Segments of the worm’s body that contain eggs

Question 24

How do Taenia saginata cause disease

Answer 24

Cattle ingest proglottides of the worm which contain eggs. Larvae hatch and migrate into the animal muscle. Humans consume infected meat, digesting the worms except for the scolex, which attaches to the gi epithelium

Question 25

What is the difference between a definitive and intermediate host?

Answer 25

The definitive host is the one which harbors the adult parasite and where the parasite reproduces sexually. The intermediate host is the host which harbors the larval stage or the asexual forms of the parasite.

Question 26

Do nematodes (round worms) have a digestive system?

Answer 26

YEs

Question 27

Which gender of nematode is larger

Answer 27

Female

Question 28

Do nematodes have a larval stage?

Answer 28

No

Question 29

Hepatitis A characteristics

Answer 29

Single strand RNA, no envelope

Question 30

Hepatitis A route of entry

Answer 30

Oral route via food and water, multiplies in GI tract epithelium

Question 31

What clinical conditions are caused by Hepatitis A (6)

Answer 31

Anorexia, malaise, nausea, diarrhoea, abdominal discomfort, fever and chills

Question 32

Hepatitis B characteristics

Answer 32

Enveloped, double stranded DNA

Question 33

Describe the two structures of Hepatitis B

Answer 33

The viral DNA is contained within a capsomere. The capsomere containing the virus may either be housed within a spherical envelope particle or a tubular/filamentous envelope particle. The virus and capsomere housed within the envelope make up a Dane particle, which is the complete HB virus. The envelope features spike proteins which act as surface antigens.

Question 34

How is hepatitis B transmitted

Answer 34

Blood and other body fluids (milk, saliva, semen) via sexual contact, non-sterile needles and other contaminated equipment, or transplacental transmission to foetus

Question 35

Which groups are more likely to get Hepatitis B?

Answer 35

Gay dudes, straight peeps with lots of partners, IV drug users, chronic carrier mothers to bebes, healthcare professionals

Question 36

Major complications of hepatitis B

Answer 36

Liver cirrhosis, liver cancer

Question 37

Does HB have high or low mortality

Answer 37

Low- around 1-3%

Question 38

How is HBsAg vaccine manufactured

Answer 38

Genetically engineered in yeast

Question 39

Hepatitis C transmission (4)

Answer 39

Intimate contact with contaminated blood Uterus from mother to foetus Oral faecal route Organ transplants

Question 40

Complication of Hepatitis C

Answer 40

50% of cases progress to chronic hepatitis

Question 41

How is Hepatitis C diagnosed and treated

Answer 41

Serological test for surface antigen, treated with alpha interferon assay and chemotherapy

Question 42

Hepatitis D characteristics

Answer 42

Single stranded RNA, no envelope

Question 43

Under what conditions does Hepatitis D infection occur?

Answer 43

The individual must also be infected with HBV so that the envelope of HBV covers the HDV capsid

Question 44

Describe the two forms of hepatitis D infection

Answer 44

Acute (coinfection) Chronic: progresses to liver damage with high fatality rate

Question 45

What is the nature of the treatment for hepatitis D infection

Answer 45

Supportive, allowing liver damage to resolve, and to use the HBV vaccine

Question 46

Hepatitis E characteristics and mode of transmission

Answer 46

Single stranded RNA, faecal oral

Question 47

Which hepatitis virus is E most similar to?

Answer 47

Hepatitis A

Question 48

Where is HEV most prevalent

Answer 48

South east asia

Question 49

What differentiates HEV from other hepatitis viruses

Answer 49

Does not cause chronic liver disease

Question 50

For which nematodes are the eggs infective for humans?

Answer 50

Enterobius vernicularis (pin worm) and Ascaris lumbricoides

Question 51

For which nematodes are the larvae infective for humans

Answer 51

Necator americanus (hook worm) and trichinella spinalis

Question 52

Which parts of the nematode life cycle occur in the host?

Answer 52

Entire life cycle occurs in one host- egg to mature adult

Question 53

Name a cause of elephantiasis

Answer 53

Vuchereria bancrofti, blocks lymphatic drainage causing swelling of leg

Question 54

Ascaris lumbricoides size

Answer 54

Large- around 30 cm

Question 55

Ascaris lumbricoides life

Answer 55

Eggs are found in animal droppings. Hand to mouth contact with infected soil or unwashed vegetables. Reside inn small intestine of human and animals, feeding on semi-digested food.

Question 56

Trichinella spiralis life

Answer 56

Encysted larvae in poorly cooked pork ingested. In SI larvae are freed from cysts, mature and sexually reproduce. Live nematodes born. Larvae enter lymph and blood, then encyst in muscles and other tissues. Cause trichinosis.