transmission

• an individual comes into direct contact with a reservoir of pathogens which are on or in their host

• an individual comes into contact with a pathogen which is outside its host • these pathogens will have to withstand the harsh environment of being away from their host

• Influenza= droplet infection - small droplets of mucus or saliva that contain the pathogen are expelled from the nose and mouth and land on mucus membrane or are immediately breathed in • Gonorrhoea= sexually transmitted • Hepatitis B= sharing needles

• Malaria= spread by bite of a female mosquito= insect is vector • Athletes foot= spread by sharing towels or socks= are fomites • Cholera= water is vector

• droplet infection and airborne transmission spread disease as either fall on to new hosts, or are inhaled sometime later • poor ventilation makes spread more likely as everyone breaths and re-breathes same infected air • sharing of beds, towel and utensils increase risk of catching disease, as skin to skin contact more likely

• good health care for early diagnosis and treatment of disease reduces spread of pathogen. • education about safe sex practices can provide information to stop the spread of HIV virus • poorer sewage infrastructure • both of these things are sometimes only accessible to those who can pay for it

• malaria is most common in tropical countries, as mosquitos can’t survive cold winters and therefore can’t colonise in the uk • also need still water to lay their eggs • increased heat provided more kinetic energy for chemical reactions so reproduction occurs faster

• direct contact (touching, sexual contact) • inoculation (animal bites, needles) • ingestion (eating/drinking)

• vectors = animals pass pathogen to humans • droplets = saliva/mucus • fomites = dirty bedding, cosmetics

• direct contact

• contaminated soil = pathogens and spore remain in soil and infect roots • vectors = wind, water, animals carry pathogens between plants