most of the time
With further understanding of viruses and other biological agents comes the unfavorable risk of individuals mutating said agents with the intent to harm. We have the potential to see these future biochemical/ viral attacks which not only emphasizes the importance of the Medical Micro Bio field but the ethical judgements for today's scientists that come with the knowledge.
SARS
SARS: viral respiratory illness caused by a coronavirus. Begins with high fever, body aches, mild respiratory symptoms often concluding with pneumonia. It spreads mainly through person-to-person contact although there is thought it is airborne. (CDC)
typhoid fever
Typhoid Fever: although rare in industrial countries it continues to pose a threat for children in the developing world. Signs and symptoms include high fever, headache, abdominal pain, and constipation or diarrhea. It spreads through contaminated food and water or through close contact with infected individuals. (Mayo Clinic)
index cases
typically hard to even identify
incorrect impression about how the disease emerges in the first place and, on the other hand, insinuate that somebody should be blamed for this outbreak,
understand index cases so that we know how diseases are coming into a community and how to stop their spread.
even though they are hard to identify, they are still very important if not critical to the spread of disease
primary cases
INDEX CASE: first documented case -versus- PRIMARY CASE: first organisms that brings the bacteria/virus into a population
"It is not uncommon for infectious agents to percolate in the environment for years or even decades without detection,"
super-spreaders
bacterium Salmonella typhi.
Salmonella Typhi = typhoid fever Salmonella Typhimurium = was the most common cause of food poisoning, now second to Entertiditis - causes typhoid-like symptoms in mice but non-fatal symptoms in humans Salmonella Entertiditis = most common cause of food poisoning in the last 20 years, very good at infection chickens without causing symptoms, so the bacteria spreads from hen to hen very quickly
who for one reason or another may be infected with a pathogen and not have that many symptoms but can shed that pathogen in a way that makes it infectious to other people
No one really knows whether Mallon was the true patient zero in the typhoid case or simply a super-spreader or super-shedder.
I can't even think of a time when we've actually known an index case,"
"You wouldn't call him 'patient zero,' but if you consider his impact in terms of the outbreak, he was critical in the spread of the disease,"
someone may have had it before him, but he was critical in spreading the disease - why patient zero is not really helpful. Index and primary case identification have more significance.
In less than four months, about 4,000 cases and 550 deaths from SARS could be traced to Liu's stay in Hong Kong.
The hospital where he worked treated SARS, and Liu might have come into contact with the virus through a patient.
"There are plenty of potential patient zeroes out there that get infected with stuff,"
The key to an outbreak, Friedrich said, is for those viruses to be transmitted from a single person to more people.
single person to multiple people around the same time, just just from one person to another, to another
In 2004, a 6-year-old boy named Captain Boonmanuch became the first confirmed casualty of bird flu in Thailand as the virus spread across Asia,
"The viruses that really circulate in humans turn out mostly to be reassortants between viruses, usually from birds and other human viruses."
virus changes as it goes from host to host (often different species)
A reassortant
Avian influenza viruses don't replicate well in humans, human influenza viruses don't replicate well in birds, but if a bird virus and a human virus gets into a pig, you can have reassortment and get totally new strains out,
H1N1 influenza emerged in humans to cause a pandemic in 1918, Friedrich said, and then a similar pandemic hit the world in 2009.
It is believed that, leading up to the 2009 pandemic, pigs became infected with a few different viruse
reassortant virus, not derived from just one source
The resulting outbreak serves as an example of how new flu viruses might enter the human population, Friedrich said.
goes through multiple organisms, changes, and then becomes the virus that makes us sick
Ebola can be introduced into the human population through close contact with the blood, secretions, organs and other bodily fluids of infected animals
Officials said he might have contracted the disease from a bat.
he virus continued to spread through contact with the body and with human bodily fluids, possibly even after the human died
Last year, there was a MERS outbreak in South Korea, and a 68-year-old man with an extensive travel history was reported to be the so-called patient zero.
He was not ill with symptoms during his travels, according to the WHO, but once he fell ill, he went to the Samsung Medical Center in Seou
May still have been infectious before symptoms showed, could have spread during travels before becoming ill
They happened to be in the wrong place at the wrong time."
it's not that tight. It's not that clean.
Zoonotic source, reassortment, microbe environment/needs, etc. all contribute to how the disease is spread and how quickly
it's not that tight. It's not that clean.
"As humans, we sort of want to make tight stories about things, and sometimes that involves blaming or saying, 'Oh, this person started the epidemic,'
Ebola is interesting, because for this infectious disease, studies found that unsafe burial practices, which involve washing and preparing the body of the deceased, apparently contributed to the infection of many people who were participating in this cultural practice
Outbreaks are not solely reliant on the index case, it depends on the likelihood of the disease to spread in a given population due to susceptibility of hosts but also environmental factors (or in human's case cultural and societal factors as well). For example the squalor unsanitary conditions of the middle ages were a breeding ground for the spread of the bubonic plague.
A reassortment
Viruses undergo mutations in a host which results in new strains that may or may not be susceptible to other hosts. For example, in H1N1 swine flu, the avian form of the virus mutated in the pig host to provide a strain that was susceptible to humans.
Mallon was forced into quarantine on two occasions for a total of 26 years
This Molly Mallon case presents an interesting medical ethical dilemma. To what extent was it right to quarantine her against her will to prevent the spread of Typhoid? Illuminates the problem with the "patient-zero" mindset and the need of society to place blame or find the cause of the problem. With the spread of disease there are a lot more layers to take into account.
super-spreader
A super spreader is a host that disproportionately infects more secondary contacts than other hosts infected with the disease (Wikipedia)
It is not uncommon for infectious agents to percolate in the environment for years or even decades without detection,"
In order for a disease to spread in a population there must be a susceptible host. Thus, if the environment is not right for the acquisition of a disease it may not occur in a population--even if the disease is present in the environment
index cases
index cases are crucial to understanding how a disease is coming into a population and thus how the disease can be controlled