summary communicable diseases a global perspective 6th edition roger weber

summary communicable diseases a global perspective 6th edition roger weber 1 / 4

summary communicable diseases a global perspective 6th edition roger weber

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summary communicable diseases a global perspective 6th edition roger weber Summary communicable diseases

• Elements of communicable diseases

Communicable disease: an illness that is transmitted form a person animal or inanimate source to another person either directly, with the assistance of an intermediate host or by a vector Epidemic: introduction of a new infection or the presence of an illness in excess of normal expectancy

Endemic: disease is constantly present in a geological area or population group

Epidemics occur when infections exceed normal levels, and endemic diseases are constantly present in a region. Communicable diseases are dependent on a person's susceptibility to infection. These diseases are more common in developing countries, often linked to overcrowding, poor hygiene, and poverty. Children are especially vulnerable to endemic diseases. Historically, many of these diseases were common in Europe but are now mainly in tropical areas.The line between communicable and non-communicable diseases is blurring as new organisms are discovered. Excessive cleanliness in developed countries may be linked to the rise in allergies and autoimmune conditions, as it limits exposure to microbes that help build the immune system. 3 / 4

summary communicable diseases a global perspective 6th edition roger weber The Agent The agent responsible for a disease can be a living organism (such as bacteria or viruses) or a physical/chemical agent. For infectious organisms, they must multiply and find a means of transmission to survive.•Asexual reproduction: Results in identical organisms; if treatment kills one, it often kills the entire strain unless a mutation occurs that makes the organism resistant

•Sexual reproduction: produces variety within the organism population, so

some individuals may survive treatments. This can make sexual reproduction a disadvantage for the organism as certain methods of control can target one sex Survival: Parasites improve their chances of survival by adapting to their hosts or the environment. Once an organism invades a host, it may remain latent until conditions are suitable for infection. The organism may also mutate, allowing it to become more efficient at reproducing, often to the host’s disadvantage. Some organisms develop stages (e.g., spores) that help them persist in unfavourable environments, requiring harsh conditions or treatments (e.g., antiseptics, heat) for destruction Transmission -Direct transmission occurs through person-to-person contact, contaminated food or water, or droplets (like sneezing).

-Reservoirs: Human or animal hosts can serve as reservoirs of disease,

with some parasites needing intermediate hosts (e.g., animals) to complete their life cycles before infecting humans

-Animals: can either be intermediate host or reservoir

-Vectors (insects or arachnids) play a crucial role in transmitting diseases like malaria and dengue by carrying pathogens from one host to another.

▪Cycle of transmission:

▪Direct insect to human ▪Insect to animal with humans entering the cycle as an abnormal host ▪Insect to animal, including humans, from which it is transmitted to other humans by the same or another vector Zoonosis

2 main groups of communicable diseases:

-Only humans involved

-With an animal reservoir or intermediate host -> zoonoses: infections that

are naturally transmitted between vertebrate animal •Zoonosis groups according to intimacy of the animal to the human

-Domestic: those invited animals that live close proximity to humans

-Synanthropic: animals that live in close association with humans, but

are not invited

-Exoanthropic: animals that are not in close association with

humans This type of classification indicates the focality of the disease

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