Human Health and Disease

What is health?

‘The state of complete physical, mental and social well-being’

To sustain a healthy lifestyle person needs: 

Good hygiene will reduce the likelihood of infection

•A balanced and varied diet •  Take exercise•  Proper shelter•   Enough sleep

What is disease? 

Disease is a disorder or malfunction of the mind or body, which leads to a departure from good health.

Can be a disorder of a specific tissue or organ due to asingle cause. E.g. malaria.

May have many causes.Often referred to as multifactorial. E.g. heart disease.

Disease diagnosed by a doctor analyzingthe symptoms (physical and mental signs).

Acute disease

Sudden and rapid onset

Symptoms disappear quickly

E.g. influenza

Chronic disease

Long term

Symptoms lasting months or years

E.g. Tuberculosis

Categories of diseases

Physical disease

Results from permanent or temporary damageto the body

It could be acute or chronic

Examples: AcuteBronchitis Cold Sores Common ColdInfluenza

Examples: ChronicAsthmaAutoimmune diseaseDiabetesEczema

Infectious diseases

Organisms that invade the body and cause disease inside arecalled pathogens

Bacteria and Viruses are the best know pathogens. They grow & reproduce within the body of their host.

Fungi, protists and parasites can also cause disease. Sometimes worms.

Diseases are said to be infectious or communicable if pathogens can be passed from one person to another.

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•Some examples to follow

•For a list of more with details see pages 250-251 in your book

Influenza ('flu)Influenza is a virus which causes a severe form of respiratory tract infection with generalized bodily symptoms. It spreads around the world in epidemics and is responsible for much ill health as well as many deaths. SymptomsIf you start to develop cold symptoms but starting more rapidly and rather more violently, with higher fever and severe aches and pains, often in the back and muscles, then you may well be developing influenza. This may be associated with severe headache, cough, and, as a result of the fever, intermittent sweating and shivering. Sometimes there is a gastrointestinal element, with vomiting and/or diarrhea. Many people think they have had "flu" when all that they have suffered is a bad cold. When you have influenza you will know the difference. Most people will find it impossible to leave their bed and feel terrible. The worst symptoms usually last for three to five days, and then should begin to improve. It is common to need two to three weeks off work as there is considerable debility left after the feverish illness is over. Do not be surprised to be quite depressed, this is a natural after-effect of the condition. Influenza makes everyone feel terrible, but most people recover. It does however have a small, but significant mortality, especially in the very young, the very old, and those with poor immunity. CausesInfluenza is caused by a virus which attacks our body cells resulting in various manifestations depending on the strain of the virus. New mutations of the virus arise all the time and unfortunately immunity against one strain (which is conferred by exposure or immunization) does not protect against other strains. In the era of rapid air transport the world wide spread of a new type of influenza can be extremely fast.

Salmonella

Salmonellosis is an infection with a bacteria called Salmonella. Most persons infected with Salmonella develop diarrhea, fever, and abdominal cramps 12 to 72 hours after infection. The illness usually lasts 4 to 7 days, and most persons recover without treatment. However, in some persons the diarrhea may be so severe that the patient needs to be hospitalized. In these patients, the Salmonella infection may spread from the intestines to the blood stream, and then to other body sites and can cause death unless the person is treated promptly with antibiotics. The elderly, infants, and those with impaired immune systems are more likely to have a severe illness

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Cholera is an acute, diarrheal illness caused by infection of the intestine with the bacterium Vibrio cholerae. The infection is often mild or without symptoms, but sometimes it can be severe. Approximately one in 20 infected persons has severe disease characterized by profuse watery diarrhea, vomiting, and leg cramps. In these persons, rapid loss of body fluids leads to dehydration and shock. Without treatment, death can occur within hours.

Zimbabwe's cholera epidemic hits 10,000

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Typhoid fever is contracted when people eat food or drink water that has been infected with Salmonella typhi. It is recognized by the sudden onset of sustained fever, severe headache, nausea and severe loss of appetite. It is sometimes accompanied by hoarse cough and constipation or diarrhea. Case-fatality rates of 10% can be reduced to less than 1% with appropriate antibiotic therapy. Paratyphoid fever shows similar symptoms, but tends to be milder and the case-fatality rate is much lower.

•         Clinical Tetanus sometimes known as “lock jaw”-Spores deposited in tissue- wound, burn, ulcer, compound fracture, operative wounds, drug injection- tetanus neonatorum: infection of umbilical stump- necrotic tissue (poor blood supply, anoxia) - mixed infections, foreign bodies also contribute-Toxins affect the central nervous system by causing continual impulses to be sent to the muscles. They contract and become remain rigid. -If not treated the person often dies a painful death as more and more of the muscles are affected.

Malaria infects an estimated 300 million people, and is spread by mosquitoes, transfusions, and shared hypodermic needles. Control of mosquito populations has led to declines in malaria in many areas. Infected individuals can be treayted with a variety of medicines. However, some of the sporozoans that cause malaria heve developed immunity to some of the more commonly employed medicines.

Malaria

Global Statistics •         40% of the world's population is at risk

•         300-500 million new cases/year •         1.5-2.7 million deaths/year

•         Malaria is endemic to over 100 countries and territories

•         More than 90% of all cases are in sub-Saharan Africa

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• Tree or Root Man, What cause it?• Dede Koswara, 'Tree Man'

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•How diseases are spread #4, p. 248

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Droplet Infection• Transmitted by pathogens

suspended in water droplets that humans cough or sneeze into the air.

• Airborne infections generally affect the respiratory tract, though some of them affect other parts of the body as well.

• The spread of these diseases is curtailed by practicing sanitary precautions.

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Contact Infections

• Some diseases are spread by direct contact with a sore or lesion on the skin or mucous membrane of an infected person.

• Scarlet fever, colds, influenza, and measles can be transmitted by touch.

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Contamination Infection

• Pathogens enter the body by way of contaminated food or water often afflict the digestive system.

• The intestinal wastes of a person who has this disease are highly contagious.1

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Wound Infections• Some pathogens

enter the body through wounds.

• Even small cuts can be serious if they are not properly treated.

• Enters through the bloodstream and spreads to other parts of the body.

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Vector-carried Infection• Insects or other arthropods

that carry pathogens to other host organisms are are vectors.

• Either mechanically, as with food contamination by pathogens carried on the bodies of flies or roaches or...

• By the bites of such organisms as mosquitoes, flies, or ticks, which inject the pathogen into the bloodstream of the host.

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Immune Carriers

• Diseases are also spread by people, and occasionally animals, who spread pathogens to others without suffering from the disease themselves

• They might have had the disease before and have developed an immunity to it.

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