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• Disease transmission can happen in 5 different ways.

  The pathogens are disease causing organisms which have a specific mode of transmission.
• Air borne transmission – when an infected person coughs or sneezes, the infected droplets are spread through the air to a healthy person. Gram positive pathogens can be spread over a short distance.

  Examples are cough, cold, influenza, tuberculosis, measles, whooping cough, chicken and small pox.
• Air borne spread are the greatest in theatres and burn units.
• Contact – major route of spread in the hospitals. Cross infection is increased due to the pathogen being on the hands of the staff and frequent handling of equipments and patients.

  There are 2 types direct and indirect.

  Direct contact is physical contact with an infected person like touching them during a physical examination

  Indirect contact is transmission through dirty hands and touching contaminated surfaces. Usually in hospitals, outpatient clinics and nursing homes.
• Contact transmission examples are ringworm, small pox, scabies, scarlet fever.
• Indirect contact – acute watery diarrhea.
• Contaminated food and water – these are easy vehicles for bacteria. This is usually due to poor hygiene.

  Disease that are caused are diphtheria, dysentry and enteric fever
• Vehicle transmission – disease transmission thorugh contaminated water, milk, food, serum and other products.

  Vehicle transmission is also known as the fecal-oral transmission.
• Contaminated water – waterborne diseases spreads when there is poor sanitation.

  Diseases are cholera, typhoid fever, viral hepatitis and E.coli.
• Vector transmission -  disease transmisison through a host like mosquitoes or the use of alternate hosts.

  Disease is transmitted from the carrier to the host usually through biting.

  The 2 main pathogen modes of transmission is mechanical and biological transmission.
• Mechanical transmission – housefly is the strongest carrier of infection. Operate as vectors for shigella.
• Biological transmission – the organism multiplies and divides in the vector. The vector and host have a complex interaction. Increase the number of progeny to contribute to an infective dose.

  There are different means of transmission. Bite and oral-fecal route

  There are 3 transmissions modes – propagative, cyclo-development and cyclopropagative.

  Propagative – multiplication without a cyclic change.

  Cyclo development is transmission with cyclic change but no multiplication

  Cyclo propagative is the parasite undergoes a cyclic development with multiplication in the host.
• Transplacental transmission – diseases contracted by the fetus from the mother through the placenta.

  Examples are syphilis, rubella, measels.
• There are 2 types of diseases - communicable and non-communicable

  Communicable – patient to patient spread – MRSA, Rabies, STD, TB, AIDS/HIV and influenza. These can cause an epidemic/endemic.

  Non-communicable diseases – not spread from patient to patient. Genetic abnormalities, cancer, diabetes, hypertension, asthma, trauma, fractures.
• Environmental measures – apart from medicine and drugs – education (water quality and safety), environemental engineering, food and climate.