lecture 18 - food borne bacteria Flashcards
what are the characteristics of Polio?
- RNA genome and a protein capsid (non-enveloped)
- enterovirus (infection occurs via the fecal oral route)
what is viremia?
the presence of viruses in the blood
what occurs in 95% of polio cases?
only transient viremia occurs and the infection is basically asymptomatic
what occurs in 5% of polio cases?
virus spreads and replicates in other tissues including muscle
what are the symptoms of 5% of cases, where viremia occurs?
minor symptoms such as fever, headache, and sore throat
what occurs in 1% of polio cases?
paralytic poliomyelitis occurs - this is a paralytic disease of when the virus enters the central nervous system and replicates in the motor neurons of the spinal cord, brain stem, and motor cortex
what is the result of paralytic poliomyelitis?
temporary or permanent paralysis
where is endemic transmission of poliovirus still occuring?
Afghanistan, Nigeria and Pakistan
what food products is poliovirus associated with?
milk and milk products
what deactivates polio virus?
pasteurization of milk above 70C for 30 seconds
what are the three serotypes of poliovirus?
PV1, PV2, PV3 - each have slightly different capsid proteins
what is the common trait between all serotypes of poliovirus?
all extremely infectious
where is PV1 most commonly found?
in nature - localized to regions of Pakistan and Afghanistan
is PV2 still present?
no, most likely eradicated
is PV3 still present?
has not been detected since 2012, so it is likely eradicated, in 2012 it was detected in Nigeria and Pakistan
what are the characteristics of Hepatitis A Virus?
non-enveloped single-stranded RNA virus
how is hepatitis A transmitted?
through a fecal oral route - usually spread by eating food or drinking water that is contaminated with infected feces
what organ does hepatitis A infect?
the liver, can cause acute liver failure (mostly in the elderly)
what are the symptoms of hepatitis A, and how long do they last for?
nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain. usually lasts around 8 weeks
what is a common source of food for Hepatitis A to occur?
shellfish
what group of people are usually asymptomatic for hepatitis A?
kids
a single infection of hepatitis A virus leads to ____
lifelong immunity
how is hepatitis A prevented?
HAV vaccine, proper hand washing and cooking
what is the treatment for acute liver failure?
transplant
where do outbreaks of HAV usually occur?
in moderately developed countries where young children have not been exposed, but vaccination is also not widespread
how did the hepatitis A virus outbreak occur in North America?
frozen strawberries imported from Egypt
HAV survives mild ____ and exposure to _____
pasteurization
high temperatures
what was the Costco 2016 outbreak?
there was HAV contamination in Nature’s Touch Organic Berry Cherry Blend in canada’s Costco stores?
what are the symptoms of HAV effects on the liver?
nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain
how does HAV travel to the liver?
initially infection generally occurs in the intestine, but then HAV enters the bloodstream
what cells can HAV multiply in, once in the liver?
hepatocytes
HAV is excreted in ____ towards the end of the incubation period?
feces
how is HAV diagnosed?
through the detection of IgM antibodies in the blood - IgM is only present following acute HAV infection
what does the presence of IgG mean in HAV infection?
that the acute phase has passed, and the person is immune to further infection
what is Norovirus (NoV)?
the most common cause of gastroenteritis, worldwide
what are the treatments of Norovirus?
none - no vaccines or effective treatments
what are the symptoms of Norovirus?
non-bloody diarrhea, vomiting, and stomach pain
what is the typical recovery period of Norovirus?
1-3 days
what are the characteristics of Norovirus?
positive-sense RNA, non-enveloped
how is norovirus transmitted?
airborne transmission due to vomiting. Virus found in vomit and germs can infect other people.
how long can people be contagious for with Norovirus?
for as long as 2 weeks after recovery
where do Norovirus outbreaks occur?
mainly long-term care facilities, cruise ships, schools, party/events, restaurants, and hospitals
what foods are Noroviruses mainly found in?
shellfish and salad ingredients
how do noroviruses enter food?
from a single infected person
what are the characteristics of Rotavirus?
a non-enveloped virus, double stranded DNA
rotaviruses are the most common cause of ____ among infants and young children
diarrheal disease
what age group is Rotavirus mortality rate highest?
children younger than 5 years - mainly in Africa
what is the significance of the Rotavirus vaccine?
licensed for use in 1998 and was thought to be 80-100% effective in preventing severe diarrhea. however, the vaccine was removed from the market in 1999 because it increased the risk of intussusception (type of bowel obstruction) in one in every 12,000 cases. a new vaccine was administered in 2006
what are the overall symptoms of Rotavirus?
nausea, vomiting, watery diarrhea and low-grade fever
what is the incubation period of Rotavirus in children?
approximately 2 days, and then symptoms. period of illness is acute
what are the starting symptoms of Rotavirus?
vomiting, followed by four to eight days of profuse diarrhea
what is the most common cause of death from Rotavirus?
dehydration from diarrhea
