B5 Biological Agents Flashcards
Definition of a biological agent
A micro organism, cell culture or human endoparasite, weather genetically modified, which may cause infection, allergy, toxicity or otherwise create a hazard to human health.
Definition of a micro organism
A microbiological entity, cellular or non cellular, which is capable of replication or of transferring genetic material.
Such as fungi, Protozoa, viruses and bacteria
Endoparasites are?
Parasites that are capable of infecting and living within the human body ie malaria (single celled organism that lives in the blood) or tape worm (large multicellular organism that lives in the gut
Fungi
Fungi include moulds and yeasts.
Some fungi cause infection on or inside the human body such as athletes foot.
Some fungi produce toxins (mycotoxins) that are harmful to humans.
Fungi reproduce by forming spores that are released to find a suitable environment, inhalation of a large number of these spores can cause lung disease, such as farmers lung.
Bacteria
Bacteria are simple single celled organisms, that vary wildly in shape, many have flagella (tails) to allow them to move through liquid.
Some form spores that can survive adverse conditions such as heat, cold.
Bacteria grow in virtually any environment, many bacteria do not cause disease because of the immune system and some are even beneficial.
Some bacteria cause disease such as legionella.
Viruses
Viruses are micro organisms but not strictly alive. They are self replicating molecules that invade a host cell to produce more viruses.
Viruses are smaller than fungi or bacteria
Hepatitis and aids are two types of viruses.
Viral infections are usually prevented or halted by the bodies immune system, this response takes time to come into effect so there is usually a period of illness before the bodies defences become active. Some viruses are so severe the immune system can nor respond effectively and serious disease or even death result (eg small pox).
Some viral infections are not dealt with effectively by the body and so can persist eg HIV the causative agent of AIDs
Protozoa
Protozoa are a very large diverse group of single celled organisms that have a cell nucleus and there for are different to bacteria which have no nucleus. Protozoa are often motile (able to move) and do not photosynthesise.
Many diseases are caused by Protozoa such as malaria.
Diseases caused by Protozoa can not be treated with antibiotics (only drugs) and the body does not usually self resolve ie the immune system is incapable of dealing with the infection independently.
Pathogenic
Pathogenic (disease causing) bacteria come from three main sources:
*Human = many fungal, bacterial and viral infections are passed from person to person, this can happen by transfer of bodily fluids eg viral hepatitis (needles) tuberculosis by droplets from coughing, sneezing or by physical cross contamination.
*Animal: similar mechanisms to humans ie rabies from a bite, leptospirosis from rat urine, usually in contaminated water.
A disease spread from animal to humans is referred to as zoonosis.
*Environmental: such as legionella which can come from damp soil and water courses.
Zoonosis
Diseases that can be transferred to humans from animals
Vector-borne diseases can be transferred via a bite such as a mosquito carrying malaria.
Zoonotic diseases Animal influenza
- Animal influenza - a viral disease from various animals such as birds, pigs, horses and dogs. In some cases this viral infection can transform and become passed between humans.
Zoonotic diseases- Cryptosporidiosis.
- Cryrtosporidiosis - an infectious diarrhoea disease. It is caused by a protozoan parasite and can be transmitted via contact with infected animals (mainly cattle and sheep), it can be caught by faecal matter contaminated water or salad and passed between humans due to poor personnel hygiene.
Zoonotic diseases- Psittacosis
Psittacosis (Parrot fever) - is primarily an infection of birds, it can be transmitted by inhaling in infected material or occasionally By oral infection. Persons at risk are usually poultry farmers, bird keepers, cleaners and construction workers (anywhere where birds live and shit).
Zoonotic diseases- malaria
Malaria- is caused by the protozoan parasite, the parasite is spread by night biting insects (mosquitoes).
Diseases caused by biological agents- Hepatitis
Hepatitis- there are at least five types of hepatitis (A,B,C,D & E).
A - is usually contracted by the faecal-oral route
The others are blood-borne and transmitted by contact with contaminated bodily fluids.
Hepatitis is the most common risk for medical staff and refuge disposal
Diseases caused by biological agents- HIV
HIV- human immunodeficiency virus is the virus responsible for AIDS ( acquired immune deficiency virus). HIV attacks the immune system by which the body cannot resist infections.
