Routes of Transmission

Routes of Transmission

Direct Transmission

  • Direct transmission occurs when the pathogen is passed directly from the infected individual to a susceptible individual.
  • This can happen through physical contact, such as touching, biting, kissing, or sexual contact.
  • Direct transmission also includes vertical transmission, where the pathogen is transferred from a mother to offspring, for example, during birth or through breast milk.

Indirect Transmission

  • Indirect transmission occurs when the pathogen is not directly transferred from the infected to the susceptible individual but involves an intermediate.
  • It can take place via fomites, which are inanimate objects that can carry pathogens, such as feeding utensils, bedding, or grooming tools.
  • Indirect transmission also involves vectors, which are organisms that transmit pathogens, such as insects. They can transmit the pathogen either passively, on their body, or actively, via a bite.
  • Airborne transmission, a type of indirect transmission, occurs when pathogens travel more than one metre through the air, for example in dust or on small respiratory droplets, to reach a new host.

Vehicle Transmission

  • Vehicle transmission is the spread of pathogens through a common source, such as food, water, or air.
  • Disease spread in this way can cause outbreaks, where a large number of individuals in the same area are infected.
  • To prevent vehicle transmission, control measures such as cleanliness and hygiene, safe food handling, and water treatment are crucial.

Vector-Borne Transmission

  • Vector-borne transmission occurs when an organism, often an insect, transmits the pathogen from one host to another.
  • Vectors can transmit pathogens passively, on their body, or actively, injecting it into the host, usually via biting.
  • Common vector-borne diseases include Lyme disease (spread by ticks) and malaria (spread by mosquitoes).
  • Prevention of vector-borne diseases often involves controlling or avoiding vectors.

Zoonotic Transmission

  • Zoonotic transmission is of special relevance in animal management. This occurs when diseases are passed from animals to humans.
  • These diseases are called zoonoses and can be caused by a range of pathogens, including bacteria, viruses, and parasites.
  • Examples include rabies, transmitted through the bites of infected animals, and avian influenza, transmitted from birds to humans.