Infetous Diseases Flashcards
Cholera pathogen
Vibrio cholerae
Which is a type of bacteria
Malaria pathogen
Four species of plasmodium
Which is a type of protoctis
Tuberculosis pathogen
Mycobacterium tuberculosis
Which is a type of bacteria
HIV pathogen
The HIV virus
Measles pathogen
A species of Morbillivirus
Which is a type of virus
Smallpox virus
Variola virus
Definition of disease
An illness or disorder of the body or mind that leads to poor health. Each disease is associated with a set of signs and symptoms
How is cholera transmitted
The infected person passes out the bacteria in their faeces, the unifected person eats contaminated food or drinks contaminated water
Differences between infectious and non infectious diseases
Infectious disease are caused by a pathogen. Non-infectious diseases include long term degenerative diseases such as lung cancer and genetic diseases such as sickle cell anaemia
Preventing and controlling cholera
Not necessarily fatal. Important that fluid loss equals fluid intake. Would be prevented with clean water and sewage treatment. Countries in dept do not have the financial resources to do this. Using human sewage to irrigate vegetables is a common cause of the disease. Common after natural disaster when drainage has been broken.
Why is the vaccine for cholera ineffective
There are multiple strains
How is malaria transmitted
When a female anopheles mosquito bites an infected person then bites a non-infected person and transmits the parasite into the persons blood stream. Can also be transmitted during blood transfusion
Where are most cases of malaria
Anopheles mosquitos live in the tropics. Countries may not have the money to eradicate mosquitos
Immunity against malaria
People can gain immunity to malaria, meaning it’s very dangerous when it spreads to places where it is not endemic. Especially areas where it only occurs during the rainy season.
Preventing malaria
Oil can be spread over water making it impossible for mosquito larvae to breath. Marshes can be drained. People covering their body at dusk when the mosquitos are most active. Sleeping under mosquito nets and wearing insect repellent
Treating malaria
There are anti-malaria drugs but some plasmodium are now resistant.
Worldwide control of malaria
In the 1950s the WHO tried to eradicate it but were unsuccessful because the plasmodium became resistant to the drugs. The program was unpopular as people lost immunity.
Worldwide concern over malaria
An increase in drug resistant forms of plasmodium. An increase in the number of cases caused by p.falciparum which causes the most severe type. Difficult to develop vaccines. Increase in cases due to climate change
How is HIV transmitted
During sexual intercours, from mother to baby through the placenta, through breast milk, due to the sharing of needles and blood transfusions
Factors in preventing HIV
Slow to show symptoms so hard to know you have it. More likely to get it if you are promiscuous or use intravenous drugs. There is no cure. Countries are reluctant to have widespread testing as it infringes on personal freedom. In Africa it is not restricted to easily identified groups such as prostitutes so it is harder to test
How to prevent HIV
Education. Using condoms. Needle exchange programs where old needles are exchanged for new ones. Contact tracing where you tell the people who the person has had sex with that they should get tested. Blood collected from donors is tested and heat treated to kill viruses.
Transmitting TB
When an infected person breaths out droplets containing the parasite and an unifected person breaths it in. So is prevalent in over crowded and poor areas. More likely to get it if your immunity is low due to malnutrition or HIV. Can occur in in unpasteurised milk or in beef
Factors in treating TB
Some strains of TB are resistant to antibiotics. As it is a long course of drugs, some people stop taking he drugs when they feel better but before the course ends. The bacteria will then spread throughout the body increasing the likelihood of a mutation arising. The WHO promotes a scheme where DOTS involves health workers ensuring the patients have taken their medication.
Preventing TB
Contact tracing. There is a vaccine but its effectiveness decreases with age. Cattle are checked for TB and milk is pasteurised.
Transmission of measles
When an infected person breaths out droplets with the pathogen in which an uninfected person breaths in.
Facts about measles
Spreads in overcrowded conditions where it is unsanitary and there is a high birth rate. Is very contagious. Infects mainly malnourished infants suffering from vitamin A deficiency.
What is an antibiotic?
A drug that kills or stops the growth of bacteria without harming the cells of the infected person.
How does penicillin work?
When a bacterial cell is growing it secretes the enzyme autolysins, which makes little holes in the cell wall. These holes allow the wall to stretch so the peptidoglycan chains can link them together. However, penicillin stops theses chains from linking up, but the autolysins keeps on making more holes. Water enters by osmosis and the cell eventually bursts.
Why do antibiotics not affect viruses or human cells?
Viruses and human cells do not have a cell walls, viruses also do not have a cytoplasm
How does antibiotic resistance arise?
When a gene within the bacterial genome changes to give rise to a nucleotide sequence which is not affected by antibiotics. When someone does not fulfill their cause of penicillin some of the bacteria survive and a mutation may occur giving resistance. The more we misuse antibiotics the greater selection pressure we place.
How can resistance be transmitted
It can be done vertically, when a resistant bacteria reproduces asexually to produce 2 daughter cells with a copy of the plasmid coding for resistance. Horizontal transmission can occur during conjugation, when a tube forms between the 2 bacteria allowing for the movement of DNA.
Consequences of antibiotic resistance
Can increase the risk of death, are associated with longer stays in hospital and complications. Can spread to different species of bacteria and some species may become resistant to multiple types of antibiotics.
Steps which can be taken to reduce the impact of antibiotic resistance
Only prescribing antibiotics when appropriate so not for a viral infection. Reducing the number of countries where antibiotics are available without a prescription. Using antibiotics which are specific to that infection. Making sure the patient completes their curse of treatment. Avoiding using it in farming to prevent rather then cure.
Why is cholera common after a natural disaster
Damage to sewers, so mixing of drinking water and sewage. Contaminated water supplies cannot be treated. Peoples immune system is weakened due to malnutrition
What is an auto-immune disease
The failure to distinguish self and non-self (antigens)
