5.1.1 Health & Disease

• The World Health Organisation (WHO) defines health as'a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity'
• This means that health is not just dependent on whether an individual is physically sick or not.
  • There are lots of factors should be considered when assessing the health of an individual which includes mental health as well as the level of social support in place

Communicable Diseases

• Communicablediseases are caused bymicroorganismscalledpathogenswhich canspreadbetween individuals or individuals and animals
  • E.g.chickenpox, a common childhood disease, is caused by a viral pathogen called the varicella-zoster virus whereasCovid-19是由SARS-CoV-2病毒引起的吗

Communicable Diseases Table

Non-Communicable Diseases

• Non-communicablediseases arenot caused by pathogensandcannot be passed onbetween individuals
  • Their effects on health tend to belonger-lasting; examples areasthma,CHDand mostcancers

• However, theriskof developing non-communicable diseases may beincreasedby certainfactors(includingdiet,stressandlifesituations) as these factors may have a profound effect on both physical and mental health
  • 吃一个均衡的饮食,提供正确的amount of energy and nutrients helps maintain good health whereas apoordietcan lead todeficiencies,obesity,diabetesandpoormentalhealth
  • Constantly being understresscan lead to cardiovascular issues (such as high blood pressure, increasing the risk of CHD) and poor mental health
  • Where a person lives and their income can have a profound impact on health - this affects the standard ofhealthcarethat is accessible to them (and what they can afford), what food they buy etc.

Risk Factors in Non-Communicable Diseases Table

• If an individual suffers from one disease, they are likely to be more susceptible to other diseases
• This is because the immune system may be compromised in some way or the different types of disease may interact in ways that negatively affect the health of the individual
  • Defects in theimmune systemmean that an individual is more likely to suffer frominfectious diseases;individuals infected with HIV eventually end up with reduced numbers of lymphocytes circulating around the body which reduces the ability of the immune system to fight opportunistic infections like pneumonia
  • Virusesliving in cells can be the trigger for cancers; the HPV virus can infect cells of the cervix in women resulting in cervical cancer developing in some cases, whereas some strains of the hepatitis virus can cause liver cancer
  • Immunereactions initially caused by a pathogen can triggerallergiessuch asskinrashesandasthma- these often develop as a result of anoveractive immune response
  • Severephysicalillhealthcan lead todepression和其他mentalillness; both can negatively impact the immune system and lifestyle choices made by the individual, further compounding the effects of poor health