virus

what are the structure of virus

1.        They don’t have a cellular structure, they often contain a DNA/RNA(never both) capsulated in a capsid

2.        There are 2 types of capsid

-coated with protein and capsid

-coated with lipid membrane: they cannot transmit through food, since this membrane is very weak

size of virus?

very small 25-300nm

can virus grow on food?and why

-it cannot since it does not have metabolism system and host is needed for replication

what is the function of food to virus?

-it acts as a vector

--              As a result, virus will not grow on food. Food only serves as a passive vechical for virus transmission

specificity of virus?

-              They have high specific in terms of host, the human virus will never affect the animal. Vice versa

what are the 2 type of virus?

1. gastroentritis:this type of virus only stay at intestines, and not pass through the membrane

   Eg. Norovirus

2. invasive: -              This virus will pass through the intestinal membrane and invade other tissue

   Eg. Haptitis A

Norovirus: what are the charcteristics of norovirus

infectious dose, incubation time, symptoms, duration

what is the transmission route for norovirus?

1.        The transmission is through faecal-oral route

2.        First person who is infected by the norovirus, will excrete faecal contain virus (10^8-9/g)to the sewage system 

3.        The sewage system may not remove the virus completely, and this will contaminate the water in the environment, which leads to more contamination

Eg.- veg/fruit watered by this contaminated water

        -shell-fish lived in this water will build up virus

        -manual process with poor hygeiene may transmit the virus to food

4.        In the end these containminated food may obtained by health human and cause transmission of the virus.

what is the transmission route of hepatits A

same as the norovirus

1. human infected with hepatitis A will excrete facal into the sweage system but the system may not remove the virus completely thus it will contaiminate the environemtn

2. virus enter the environment, as a result contaminate  other food product (eg. Veg, fruit, shell-fish accumulated in the shell-fish’s body

3. human obtain the infected food also be infected.

what type of virus is hepatitis A

invasive virus

How does hepatitis A differ from norovirus in terms of invasion, incubation time, and symptoms?

what are the 4 methods to observe virus

1. use tissue culture

2. use electronmicroscope

3. use Elisa

4. use PCR

   

what is surrogate virus

1.        surrogates virus that have similar characteristics with target virus and might behave similarily under certain circumstance.

what is the determine method specifically for norovirus?

-surrogate method

how to prevent virus?

1. use uncontainminated water to clean the food

2. prevent fishing at the containminated water region

3. good hygiene of the food factory

4. strict hygiene rule for the food workers

5. heating the food product adequatly