infectious diseases Flashcards
disease
an illness or disorder of the body or mind that leads to poor health, each associated with a set of signs and symptoms.
infectious disease
disease caused by pathogens
non-infectious diseases
disease not caused by pathogens. including genetic disease, cardiovascular, deficiency and mental diseases.
ENDEMIC
a disease that is permanent in a particular region or popuation
epidemic
a disease that appears suddenly and spreads rapidly across a population/area
pandemic
an epidemic that spreads wider, as far as international
incidence
the number of people who are diagnosed within a certain time period
prevalence
the number of people with the specific disease at any one time
mortality
the number of people who die of the disease.
retrovirus
a virus that reverse transcribes RNA into DNA within the host chromosomes using the enzyme reverse transcriptase, allowing the integration of the retroviral dna into the human dna
t-helper cells
white blood cells produced by the body to activate the immune system in response to a pathogen
HIV modes of transmission
semen/vaginal fluid during sex
blood
vertical
HIV global distribution
worldwide, particularly Africa and SE Asia
incubation period
few weeks up to 10 years
site of pathogen action
T-helper lymphocytes, macrophages, brain cells
clinical features of HIV
flu-like symptoms and then nothing.
weakens immune system to pneumonia, TB, dementia, vomiting etc
diagnosis of HIV
testing blood, saliva, urine for HIV antibodies
HIV treatment
drug combination, interrupting reverse transcription of virus
AZT + 2 protease inhibitors)
why hasn’t a HIV vaccine been invented yet?
because continually changes antigens
prevention of HIV
encouragement of male circumcision/faithfulness
education on cause and effects of infection
free provision of barrier contraceptive methods and sterile needles
screen blood from donors
control of HIV
contact tracing funding of testing/drug supply drug therapy vaccine research bottle-feed HIV mother's children
Tuberculosis
mycobacterium tuberculosis
mycobacterium bovis
TB modes of transmission
mycobacterium tuberculosis is spread by droplets in the air when an infected person coughs
m bovis via uncooked meat and unpasteurised milk (originally given to cows by badgers)
global distribution of TB
worldwide
incubation period
few weeks to several years
site of action
primary infection in lungs, secondary in lymph nodes, bones and gut
clinical features of TB
racking cough, coughing blood, chest pain, shortness of breath, fever, sweating, weight loss
diagnosis of TB
sputum examination, chest x ray,
problems w TB prevention
many show no symptoms until your immune system is compromised.
bacteria have lipid-rich walls, preventing them from drying out so that they last long
prevalent in developing countries w poorer living conditions (overcrowded and ill-ventilated
immigration has brought back to UK
strains have developed resistance to the drugs, further increased by partial treatment
prevention of TB
streptomycin antibiotics contact tracing patient isolation BCG vaccine combination of 4 drugs
malaria
plasmodium malariae protoctist
process of malaria vector transmission
female anopheles mosquito takes a blood meal from an infected person (to gain protein to lay eggs), taking pathogen gametes with it, before they fuse in gut to form infective stages which are passed on through the salivary glands with the anticoagulant, multiplying in an uninfected person’s bloodstream
methods of transmission of malaria
vector of female anopheles mosquito, blood transfusions, unsterile needles, vertically
malaria global distribution
tropics and subtropics
incubation period malaria
one week to a year
malaria site of action
liver, red blood cells, brain
malaria clinical features
vomiting, nausea, fever, anaemia, muscle pain, shivering, sweating, enlarged spleen
malaria diagnosis
blood examination/ dipstick test
malaria treatment
anti-malarial drugs acting as prophylactics
chloroquine prevents protein synthesis and so parasitic spread
proguanil inhibits sexual reproduction of plasmodium
problems w malaria treatment
drug-resistance insecticide resistance expensive loss of immunity made villages more vulnerable migration of people climate change vaccine development difficulty insecticides mess w food chain, having knock-on effects on wildlife
prevention of malaria
reduction in numbers of mosquitoes via oil spreading, draining ditches, biological control, fish stockponds, BT toxin,
prevention of biting via mosquito nets sprayed w insecticides/ lack of skin exposure
cholera
bacterium vibrio cholerae
transmission of cholera
food/water borne
acquired in faeces contaminated water sources, fly-contaminated food, raw shellfish
cholera incubation
2 hours to five days
cholera site of action
small intestine walls
multiplies and attaches itself to epithelial membrane before releasing choleragen toxin, triggering ion and water loss
cholera clinical features
severe diarrhoea, vomiting, fever, dehydration and weakness
cholera diagnosis
faeces analysis
cholera global distribution
endemic in Africa, India, Pakistan, Bangladesh, central/south America
cholera treatment
oral rehydration therapy
IV
glucose drinks enable further absorption of ions into gut
fluid intake matching fluid loss so as to maintain osmotic balance
choleragen structure
2 protein complex (A sub-unit and 5 B sub-units).
B is the binding protein which attaches the complex to a glycolipid on the cell surface membrane. A subunit is the enzyme that activates other membrane enzymes, causing the secretion of chloride ions into the gut lumen and inhibits sodium ion uptake
cholera prevention
irrigation of vegetables w clean water and improvement of sanitation
vaccine is short-term and ineffective
MEASLES
retrovirus called morbillivirus
measles transmission
droplets when infected sneezes/coughs
measles incubation
10-14 days before rash appear and fever develops
measles site
respiratory mucous membranes, lymph glands, upper-respiratory tract
measles clinical features
red and light-sensitive eyes, fever, rash, white spots in mouth and throat
can lead to pneumonia, encephalitis, hepatitis or blindness
measles treatment
pain and fever reducing medication
anti-viral medication if complications occur
bed-rest
medicine
measles distribution
worldwide
measles prevention
prior vaccine (MMR vaccine comprised of 3 attenuated strains and later boosters)
