INFECTIOUS DISEASES

Patience Precious Lita Kamaliza, BSc.

0888875177
patiencelita@gmail.com
Success criteria

 Outline selected infectious diseases.

 Describe types of cancers.

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Understanding related terms
 Infectious diseases: these are diseases that can be transmitted
from one organism to another.

 Infection: an infection is the invasion and multiplication of

pathogens in the body. Infections can be caused by viruses,
bacteria, fungi or protozoa.

 Disease: it is a disordered state of the organ or body of an

organism. 3
Understanding related terms conti…

 Incubation period of a disease: this is the period taken from the

day of infection and the onset of symptoms of a disease.

 Pathogens: these are disease-causing organisms. e.g Plasmodium,

Vibrio cholerae.

 Vector: an organism that carries pathogens from an object or

organism to another organism.
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Mode of transmission of infectious diseases
 Infectious diseases can be transmitted through the following
modes:
1. Air
2. Water
3. Food
4. Vectors
5. Direct contact

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Mode of transmission of infectious diseases
conti…
1. Through air- some diseases are spread through contaminated
air. These diseases are called airborne diseases e.g TB.

2. Through water- some diseases are spread through drinking of

contaminated water. Such diseases are called waterborne
diseases e.g cholera.

3. Through food- some diseases are spread through consumption of

contaminated food. e.g Typhoid.
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Mode of transmission of infectious diseases
conti…
4. Through vectors- some diseases are spread by vectors which
carries pathogens from one place/organism to another organism.

5. Through direct contact- some diseases are spread by direct

contact with an infected person or their clothing e.g HIV/AIDS.

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Diseases caused by bacteria

1. Tuberculosis (TB)
 TB of the lungs (pulmonary tuberculosis) is caused by a bacterium
called Mycobacterium tuberculosis.
 TB of the bones is caused by a bacterium called Mycobacterium bovis.

Mode of TB transmission
 Air droplet from breathing or sneezing.
 Dry infected sputum in the particles of dust.
 TB of the bones is transmitted through drinking contaminated milk. 8
1. Tuberculosis (TB) conti…
Signs and symptoms of tuberculosis
 General weight loss and fatigue.
 Fever.
 Chest pains.
 Sweating at night.
 Sputum may contain blood.
 Persistent diarrhoea.

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1. Tuberculosis (TB) conti…
Prevention, treatment and control of tuberculosis
 Drink clean boiled milk.
 Always stay in well ventilated homes.
 Avoid overcrowding places.
 Immunization of children with Bacillus Calmate Guerin (BCG) vaccine.
 Isolate the patient.
 Dairy cows must be vaccinated.
 Use of drugs such as isoniazid and streptomycin.

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2. Pneumonia
 This is an infection of the lungs in which there is accumulation of fluid in
the alveoli hence the lungs become solid resulting to difficulties in gaseous
exchange.

 It is caused by a bacterium called Pneumococcus.

Mode of transmission
 Through air droplet.
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2. Pneumonia conti…
Prevention, control and
Signs and symptoms
treatment
 Chest pains.  Live in well ventilated homes.
 Headache.  Vaccination.
 Coughing.  Avoid overcrowding areas.
 Difficulties in breathing.  Use antibiotics such as erythromycin,
 Fever. penicillin and tetracycline

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3. Cholera
 Cholera is an acute infection of the intestinal tract caused by bacterium
called Vibrio cholerae.

 Vibrio cholerae has an incubation period of 1-6 days. They multiply rapidly
in the small intestines.

Effects of vibrio cholerae on the host

 Vibrio cholerae produce highly toxic substances. These toxic substances are
responsible for the severe symptoms of cholera.

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3. Cholera conti…
Adaptive characteristics of vibrio cholera
 It can survive in areas of low oxygen concentration like in the
small intestines.

Mode of cholera transmission

 Food contamination
 Water contamination
 Object contamination

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3. Cholera conti…
Signs and symptoms of cholera
 Severe diarrhoea
 Abdominal pains
 Severe vomiting
 Acute thirst and muscle cramps
 Dehydration
 Watery stools

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3. Cholera conti…
Prevention of cholera
 Proper disposal of human and domestic wastes
 Personal hygiene
 Food hygiene
 Water treatment
 Education awareness campaigns
 Vector control

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3. Cholera conti…

Treatment of cholera
 Use of antibiotics

 Administering Oral Rehydration Solution (ORS) to the patient

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4. Typhoid
 Typhoid is caused by a bacterium called Salmonella typhi. It affects the
alimentary canal.

 It has an incubation period of two weeks.

 It attacks the walls of the intestines thereby causing ulcers. In extreme

conditions it breaks down/cut the intestines leading to death.

 Salmonella typhi can survive in areas of low oxygen concentration like that
of small intestines.
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4. Typhoid conti…

Mode of typhoid transmission

 Food contamination

 Water contamination

 Object contamination

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4. Typhoid conti…
Signs and symptoms of typhoid
 Mild fever
 Slight abdominal pain
 Ulceration and rupture of the intestines
 Diarrhoea
 Constipation
 Headaches

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4. Typhoid conti…
Prevention of typhoid Treatment of typhoid
 Proper disposal of human and
 Use of antibiotics
domestic wastes
 Personal hygiene
 Food hygiene, treatment and
preservation.
 Water treatment
 Education awareness campaigns
 Vector control
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Diseases caused by virus

1. Common cold
 It is caused by a variety of viruses.
 It affects the respiratory system.

Mode of transmission
 Through air-droplets; through coughing and sneezing from infected
person.

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1. Common cold conti…
Signs and symptoms
 Running nose
 Sore throat
 Fever
 Sneezing
 Nasal and bronchial irritation resulting to coughing

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1. Common cold conti…
Prevention of common cold
 Live in well ventilated rooms.
 Avoid overcrowded areas.
 Isolation of patients.

Treatments of common cold

 Taking prophylactic drugs.
 Taking a lot of fluids as recommended by physician.

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2. Influenza (Flu)
 It is caused by the influenza virus.
 It affects the respiratory system.

Mode of transmission
 Droplet infection through air.
 Touching items contaminated with the virus and touching the mouth.

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2. Influenza (Flu) conti…
Signs and symptoms
 Fever and chills
 Headaches
 General body weakness
 Body aches
 Dizziness
 Sneezing and sore throat
 Nausea and vomiting
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2. Influenza (Flu) conti…
Prevention of Flu
 Live in well ventilated rooms
 Avoid overcrowded conditions
 Use of cloth when coughing and sneezing

Treatment
 Use of antiviral drugs in severe cases
 Use of cough syrups
 Use drugs that lower fever.
NB: there are no specific drugs for influenza
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3. Measles
 Measles is caused by a virus. There are two viruses that cause measles and
these are:
i. Rubella virus- causes the German measles.
ii. Rubeolla virus- causes ordinary/red measles.
 They have an incubation period of 10-14 days.

Mode of transmission
 Through air droplet
 Through contaminated eating utensils and clothes.
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3. Measles conti…
Signs and symptoms
 Sore throat  Swollen glands
 Running nose  Loss of appetite
 Skin rash  Reddened eyes
 Swollen eyes  Headaches
 Coughing  Small white spots in the mouth called
 Fever koplik spots.

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3. Measles conti…
Prevention
 Vaccination.
 Isolation of the patient.
 Do not share eating utensils and clothes with the infected person.

Treatment
 There is no specific treatment for the disease.

NB: Survivors of measles get natural active immunity, the can never been
affected again by measles.
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4. Chicken pox
 This is a skin disease caused by a virus called Varicella zosta.
 It has an incubation period of 14-15 days.

Mode of transmission
 Through air-droplets
 Contact with the infected person and their clothes.

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4. Chicken pox conti…
Signs and symptoms
 Rashes on the skin
 A lot of itching on the skin rashes
 Mild fever

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4. Chicken pox conti…
Prevention
 Through vaccinations.

Treatment
 There is no specific treatment.

NB: a person who recovers from chicken pox gets active natural immunity
hence can never get infected again with chicken pox.

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Diseases caused by fungi

1. Ringworm
Signs and symptoms
 It is caused by a fungus called Tinea.
 Round grey patches on the head and
Mode of transmission face.
 Direct contact with infected  Itching on the grey patches.
areas/heads.
 Hair loss on the patches.
 Using infected combs or shaving
equipments.
 Sharing head brushes and hats.

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1. Ringworm conti…
Prevention
 Avoid sharing combs, hats and brushes.
 Hygiene in the care of hair.

Treatment
 Using fungicides creams and tablets.

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2. Thrush/Candidiasis
 It is caused by a fungus called Candida albicans.
 It can occur in the mouth, vagina and intestines.

Mode of transmission
 Through sexual intercourse.
 Infants can be infected in the mouth during birth.

NB: Thrush is mainly transmitted through sexual intercourse though it may

also arise due to changes in acidity of the vagina in females during pregnancy
or diabetes.
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 2. Thrush/Candidiasis conti…
Signs and symptoms
 Fluffy white patches on infected area.
 Severe irritation of the formed patches.
 Red inflamed skin on patches.

Prevention and treatment

 Protected sexual intercourse.
 Pregnant women must seek medical care to prevent thrush transmission to the
baby.
 Use drugs (lotion an creams) for vaginal infections.
 Use drugs such as clotrimazole.
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3. Athlete's foot
 This is a fungal disease that affects
feet in human beings.  Keeping the feet wet for prolonged
periods of time.
 It is caused by a fungi called
 Excessive sweating in the feet.
Dermatophytes.
 The infection is common in warm
Mode of disease transmission
wet areas.
 Contact with infected feet, floors,
It mainly occurs due to: socks, shoes and mats on which
people walk barefooted.
 Wearing closed shoes for a long
time.
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3. Athlete's foot conti…
Signs and symptoms
 Itching of the feet.
 Pain in between the toes.
 Swollen, peeling and craved skin between the toes.

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3. Athlete's foot conti…
Prevention
 Proper drying of feet after bath.
 Use of sandals in public showers.
 Change socks frequently.
 Disinfecting communal bath floors and showers.

Treatment
 Using anti-fungal drugs such as grisefulvin in form of powders and creams.
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Ways of preventing and controlling diseases at
household and community levels
1. Water treatment.
2. Proper disposal of human and domestic wastes.
3. Personal hygiene.
4. Food hygiene, treatments and preservations.
5. Vector (pest) control.
6. Health services.

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Ways of preventing and controlling diseases at
household and community levels conti…
1. Water treatment
 Removing undesirable properties of raw water to make it safe for human
consumption.
 Water treatments like boiling and chlorination kills pathogens present in
the raw water.

2. Proper disposal of human and domestic wastes.

 Use of pit latrines, toilets and sewage systems to dispose wastes.
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Ways of preventing and controlling diseases at
household and community levels conti…
3. Personal hygiene
Practice of observing cleanliness of external body parts to reduce the risk of
infections. It includes:
 Washing hands with soap and clean water before handling food.
 Washing hands after using the toilets, handling body secretions like mucus
and blood, garbage and when you get home from a journey.
 Washing hands daily to eliminate body odour and bacteria.
 Washing hands after changing diapers of a child.

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Ways of preventing and controlling diseases at
household and community levels conti…
4. Food hygiene, treatments and preservations
Hygiene handling of food to prevent contamination

 Washing raw food with clean water before consumption.

Processing of food to prevent spoilage, food poisoning and spread of

diseases.

 Following all required food preservation methods.

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Ways of preventing and controlling diseases at
household and community levels conti…
5. Vector/pest control
 Management of vectors such as flies and cockroaches since they are capable
of transmitting pathogens e.g by using chemicals to kill them.

6. Health services
 Providing treatment of diseases to prevent their spread.
 Provision of safe water and sanitary services.
 Public awareness campaigns.
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 Non-infectious diseases
These are diseases that can not be transmitted from one person to another.
These include:
1. Nutrition deficiency diseases.
2. Genetic diseases.
3. Mental diseases.
4. Ageing diseases.
5. Human induced diseases (due to alcohol, drug abuse etc.).

 Cancer is one of the non-infectious diseases to be explained under this sub

topic.
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 Cancer
Cancer is a disease characterized by excessive uncontrolled growth of
abnormal cells which invade and destroy body tissues.

 Cancer cells divide through mitosis.

 Cancer begins when some normal genes mutates and become abnormal;
oncogenes. Oncogenes triggers production/division of irregular mass of
relatively undifferentiated cells called tumors.

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 Cancer conti…

 Cancer cells spread to other parts of the body either by blood or lymph, a

process called metastasis.

 Substances that are capable of causing cancer are called carcinogens.

 Substances that causes mutations are called mutagens.

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 Cancer conti…
Examples of cancers NB: Breast cancer is common in
 Skin cancer. women while lung cancer is common
 Lung cancer.
in men.
 Colon cancer.
 Kaposi sarcoma.  Cancer may also affects other parts
 Cervical cancer. of the body such as liver, throat,
 Leukemia. prostate glands, colon, blood. Etc.
 Breast cancer.
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Types of cancer
There are two types of cancers and these are:

1. Malignant cancer(tumor)
2. Benign cancer (tumor)

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Types of cancer conti…
1. Malignant cancer(tumor)
 This is cancer in which tumor cells spread and invade other body
cells/tissues.
 These tumors undergoes metastasis.

Examples of malignant tumors include:

oLiposarcoma
oOsteosarcoma etc.

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Types of cancer conti…
2. Benign cancer (tumor)
 Cancer in which tumor cells do not spread and invade other body cells.
 They grow on one part of the body.

Examples of benign tumors include:

oLipoma
oWarts
oFibroids etc.

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Causes of cancer
1. Heredity
 Getting cancer because of inherited genetic defects.

2. Radiations
 Some types of radiations penetrate body cells and interfere with
chromosomes thereby leading to formation of oncogenes.

3. Some virus infections

 DNA and RNA of some viruses may have oncogenes that when injected into
body cells they may cause cancer.
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Causes of cancer conti…

4. Chemical mutagens present in diets and other inhaled or

consumed products
 Chemicals such as mercury, artificial food sweeteners and food preservatives
reacts with DNA bases making normal genes to become oncogenes.

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Examples of dietary carcinogens
Food Active agent (carcinogen)
1. Alcohol -Acetaldehyde
2. Mushroom -Hydrazine
3. Mould growth in peanut, grains etc. -Aflatoxins
4. Food cooked in oven -Nitrosamines
5. Preserved sausages, meat etc. -Nitrosamines
6. Coffee, tea, chocolate -Caffeine

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Characteristics of cancer cells
 They are capable to develop their own blood supply.

 They undergoes metastasis.

 They form tumors.

 They have abnormal nucleus.

 They lost restraint of normal growth.

 They are insensitive to growth-inhibitory signals.

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Effects of cancerous cells in the body
1. They compete with body cells for nutrients.

2. They may cause death of cells, tissues and organism at large.

3. They cause malfunctioning of some body organs.

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Factors that increase the risk of cancer

1. Smoking

2. Excessive consumption of alcohol

3. Some viral infections

4. Over-exposure to some chemicals

5. Over-exposure to radiations

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Factors that increase the risk of cancer conti…
1. Smoking
 Both smoke from direct or indirect smoking contain a substance called tar
which contains carcinogens that are known to initiate cancer in the lungs,
mouth and throat.

2. Excessive consumption of alcohol

 Alcohol damages the liver cells making them susceptible to develop cancer.
 Alcohol has potential carcinogens that initiate cancer in the liver and the
throat.
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Factors that increases the risk of cancer conti…
3. Some viral infections
 DNA and RNA from viruses may have oncogenes that increases risk of
cancer in the body.

4. Over-exposure to some chemicals

 Some chemicals in foods and occupational exposures may have carcinogens
that initiate cancer in the body.

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Factors that increase the risk of cancer conti…

5. Over-exposure to radiations

 X-rays, beta and Ultraviolet rays increases risk of cancer. They react with
bases of DNA in body cells increasing chances of oncogene making.

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Treatments of cancer

1. Surgery

2. Chemotherapy

3. Radiotherapy

4. Hormone therapy

5. Gene therapy

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Treatments of cancer conti…
1. Surgery
 A medical operation to remove the tumor or affected tissue or affected
organ.

2. Chemotherapy
 The use of drugs (medicines) that stops cancer development in the body.

3. Radiotherapy
 The use of ionizing radiation to kill cancer cells in targeted areas in the
body.
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Treatments of cancer conti…

4. Hormone therapy
 Inhibiting some body hormones or change the way they work because they
are promoting some cancers.

5. Gene therapy
 Repairing diseased cells by replacing defective genes.
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Ways of preventing and controlling cancer

1. Immunization
 Get immunized for some viral infections such as Hepatitis B to limit
liver cancer and Human Papilloma Viruses that leads to cervical cancer.

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Ways of preventing and controlling cancer conti…
2. Avoid risky behaviours
Some risky behaviours increases the risk of developing cancers e.g.
Multiple sexual partners where unprotected sex is done. Both vaginal and
anal sex. This is because:
 HIV and AIDS increases the risk of anal, cervical and lung cancers
among others.
 Human Papilloma Viruses (HPV) is associated with cervical cancers.
 Hepatitis B and C increases risk of liver cancer.

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Ways of preventing and controlling cancer conti…
3. Living a healthy lifestyle
 Avoid smoking to reduce the chances of lung, mouth, larynx and oesophagial
cancer.
 Eating plenty of plant foods such as fruits and vegetables which are rich in
vitamin C, A, E and Selenium. These are antioxidants which neutralizes
chemicals before they cause mutations.
 Avoid excessive alcohol consumption to avoid lung and colon cancers.
 Limit fat in the diet.

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Ways of preventing and controlling cancer conti…

4. Protect people who are at high risk of cancer due to occupational

exposure.
 People working in environments of high radiations or chemicals must be
given necessary protective wear.

5. Cancer screening
 Cancer screening for people who are at risk or those having suspected cancer
signs.

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Ways of preventing and controlling cancer conti…

6. Early cancer treatment

 Treating cancer in early stages is easier than in late stages.

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Management of cancer

It includes palliative care.

Palliative care is a specialized medical care for people with serious illnesses.

 The aim of palliative care is to relieve patient from pain, stress and
discomfort brought about by the illness.

 It is done by a team of medical personnel and other health specialists.

 It is used to provide support to cancer patients and other patients with

terminal illnesses.
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Management of cancer conti…
Palliative care helps the patient to cope with issues like:
 Depression
 Side effects of drugs
 Difficulties in breathing
 Constipation
 Fatigue
 Pain
NB: A terminal illness is any illness that has reached a stage where it will
automatically lead to death. (It can not be reversed by any form of treatment)

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