summary communicable diseases a global perspective 6th edition roger weber
,summary communicable diseases a global perspective 6th edition roger weber
, summary communicable diseases a global perspective 6th edition roger weber
Summary communicable diseases
1 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.
, 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
,summary communicable diseases a global perspective 6th edition roger weber
, summary communicable diseases a global perspective 6th edition roger weber
Summary communicable diseases
1 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.
, 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
