PBL Week 4 Flashcards
How are do drugs work and how are they metabolised within the body?
Drugs work by entering the body, acting on specific receptors (enzymes, ion channels, transport channels) to perform a measurable change on the body’s processes. It is then metabolised and excreted. The main function of this metabolism is to increase the water solubility of the drug, the chemical modifications involved either increasing or decreasing the drug’s half life, which can involve turning an inactive drug to an active one (codeine to morphine).
The main organs involved in drug metabolism is the liver and the small intestine (for oral drugs only). Some drugs are inactivated on the first pass through these organs; if this is the case, this drug cannot be taken orally. In the liver, the enzyme group cytochrome p450 are the main enzymes that are involved with the metabolism of drugs.
How does the immune system deal with larger parasites (e.g worms)?
An immune response to parasites triggers an IgE (Immunoglobin E) response. The IgE binds to receptors on mast cells, basophils and eosinophils. This leads to the release of cytokines (by mast cells in the blood and basophils in the blood) to co-ordinate the immune response and degranulation (by eosinophils), where cells release antimicrobial or cytotoxic molecules from certain secretory vesicles called granules. The purpose of this is to kill the parasite.
What are neglected tropical diseases and what are some examples?
Neglected tropical diseases (NTDs) are a group of tropical infections common developing regions of Africa, Asia and the Americas. They are endemic in 149 countries. They all share common characteristics; high mortality rate, disfigurement/blindness and malnutrition.
One example is Chagas disese, caused by the parasite Trypanosoma cruzi. Is endemic to Latin America. Transmission through certain biting bugs (cracks in mud houses are ideal habitat), blood transfusion and contaminated food/drinks. Symptoms occur decades after infection and include dysfunction, heart disease and enlargement of GI tract.
Another example is Schistosomiasis. Caused by the parasites Schistosomes. Found in Africa, Middle East, Asia and Latin America. Transmission through infected water; the worms penetrate the skin. Originally growing in water snails, the worms enter the humans, grow and lay eggs, which are excreted from the human to restart the cycle. Symptoms include abdominal pain, diarrhoea, bloody stools and liver/spleen enlargement. If it reaches the genital area, it can cause haematuria, fibrosis of bladder, kidney damage and bladder cancer.
What are the different ways parasites can enter the body and what is a vector?
Some parasites don’t enter the body, instead living on our skin or hair (e.g lice) and are called ectoparasites. Those that do enter the body enter through ingestion, enter through the skin (either by burrowing or by a bug bite) or sexual contact. The parasites either divide in the host (protozoa) or just live in the host (helminths).
A vector is an organism that carries the disease to other organisms (such as humans), often without being affected by the disease itself. Examples include fleas/rats carrying Bubonic Plague and mosquitos carrying Malaria.
What is the meaning of the term globilisation and what does that mean for neglected tropical diseases?
Globilisation is the process of interaction and integration of people worldwide. As globilisation increases, communities become less isolated from one another and transport between them increases. While this is mostly a positive thing, it can have unintended consequences. One of these is that, with people travelling more and more from developing countries to more developed ones, there is an increased risk for NTDs to spread. For example, someone could pick up a parasite from Africa and accidentally spread it to the UK.
What is epidemiology and what are the key terms associated with it?
Epidemiology is the study of the distribution and determinants of disease among populations. It is used to plan strategies to prevent disease. Key terms:
Incidence - Rate of occurence of new cases.
Prevalence - Proportion of cases in a population at a given time.
Outbreak - A sudden increase in occurences of a disease.
Endemic - The habitual presence of a disease in an area.
Epidemic - A serious outbreak in a single population or area.
Pandemic - An epidemic which spreads around the world to many different populations and areas.
What are the principles of disease control in the UK?
Planning and Preparedness (e.g having a plan in place for outbreaks, reserving emergency hospital beds for large spikes in hospitalisations, etc).
Prevention and Early Detection (e.g vaccinations, having certain diseases on a watch list, reporting instances of certain diseases that are at risk of an outbreak, etc).
Investigation and Control (e.g creating maps of disease cases, finding patient zero, quarantining groups of people, implementing lockdown measures etc).
Wider Public Health Management and Leadership (e.g creating clear advice for the public to follow, acting proactively rather than reactively, emphasising the danger of the disease etc).
What are the preventive measures use in controlling diseases caused by parasites?
Practicing safe sex, washing hands regularly, eating properly prepared food and drinking clean water, avoiding water sources contaminated by human waste, taking prophylaxis medication (e.g anti-malarial drugs) before travelling to at-risk areas.
What is the role that pharmaceutical companies have in treating NTDs?
Morally, they do have a responsibility to create drugs to combat NTDs, even if it isn’t financially viable. Pharmaceutical companies have come under fire in the past for this; a drug was developed that was able to treat sleeping sickness, however pharmaceutical companies allegedly stopped production of it. A year later, however, it was found that they had been using it in face creams, leading to a public outcry. In 2012, 9 pharmaceutical companies signed the London Declaration of Neglected Tropical Diseases, pledging to control or eliminate 10 NTDs by 2020.
It’s not just pharmaceutical companies that have this responsiblity, however; governments and scientists all over the world should be working to find treatments for these diseases.
Do Western Countries have anything to fear from NTDs?
While some NTDs, such as various types of worms and even Chagas disease, are actually present in western nations, they can be easily treated using western medicine. For example, Chagas disease can usually be cured if treated straight away; it’s due to the lack of medical services in developing countries that lead to it becoming an issue. However, climate change does carry the risk of NTDs coming to western nations; for example, if the UK were to become warm enough, it’s possible Malaria could become endemic here.
