UNIT 15: CLASSIFICATION AND PATTERNS OF DISEASE
UNIT 15: CLASSIFICATION AND PATTERNS OF DISEASE
Key Unit Competence
Describe the social factors that affect good health and apply knowledge gained in
familiar and unfamiliar contexts.
Learning objectives– By the end of this unit, I should be able to:Introductory activity
– Explain what is meant by health and disease.
– Identify different categories of disease and give an example of each.
– Explain the theory of the disease and the causes, sources, transmission,
symptoms and controls of the disease.
– Discuss how global patterns of disease are studied.
– Analyze and interpret records from a given hospital to identify diseases as
endemic, epidemic or pandemic.
– Apply knowledge gained to classify common diseases.
– Appreciate the importance of germ theory of disease by showing that thedeath rate related to infections is greater than those caused by accidents.
a. Suggest measures to be taken for addressing issues related to eating without15.1. Germ theory of diseases
washing hands.
b. Discuss on different communicable diseases got from eating without washinghands.
Activity 15.1
Discuss the following questionsa. What are the causes of death?The germ theory states that many diseases are caused by the presence and actions
b. Why it is difficult to eradicate malaria in Rwanda?
of specific microorganisms within the body. In 1677, Antoni van Leeuwenhoek was
the first to observe microorganisms in the droplets of water. But he did not make
the connection with disease. Later, Spallanzani and Louis Pasteur observed germs
in the blood of people suffering from disease. They suggested that the germs were
an effect of the disease rather than the cause. The observations and actions of
Ignaz Semmelweis, Joseph Lister and John Snow were a great contribution to the
acceptance of germ theory. However, the laboratory works of Louis Pasteur in the
1860s and Robert Koch in the following decades, provided the scientific proof for
germ theory. Their works opened the door to research related to the identification
of disease-causing germs and potential life-saving treatments.
15.1.1. The work of Louis Pasteur and Semmelweiss
The work of Eduard Jenner and Ignas Semmelweiss showed that infectious diseases
maybe caused by an infectious agent or germ. This was accepted as the germ theory
of disease for a very long time. The work of Robert Koch and Louis Pasteur led to a
wide acceptance of the germ theory
Pasteur made a number of important steps forward. He indicated that fermentation
is the result of the action of microorganisms (Yeast) on sugar. Huge number of people
at the time believed that living things could arise spontaneously from non-living
things and this theory is known as spontaneous generation. To reject this theory,
he showed that if broth is boiled in a sealed container, it would stay clear, but once
he added material which had been exposed to the air, microorganisms grew in the
broth. Finally, he designed a series of experiments using swan necked flasks which
showed once and for all that any microorganisms which appear in boiled broth
come from the air not arise spontaneously from nonliving organism such as broth.
In 1845-1846, Pasteur found a way of avoiding the disease of silkworms by observing
the infected eggs under microscope and thereby saving the silk industry. This was
the first clear evidence of microorganisms causing disease. Pasteur even developed
vaccines against a number of these diseases.
15.1.2. Summary of the contributions of Louis Pasteur in microbiology
and medicine
The contribution of Louis Pasteur in microbiology and medicine also include:– The fight against spontaneous generation theory15.1.3. The Germ Theory and Koch’s Postulates
– The technique of sterile culturing of microorganisms
– The technique of fermentation and conservation of drinks. This technique is
known as Pasteurization.
– The technique of antiseptic surgery to prevent contamination of wounds
during the surgical operations in hospitals.
Louis Pasteur developed the germ theory of disease which postulates that allcontagious and infectious diseases must be caused by pathogenic microorganisms.
Diseases can be spread by air, water, food, and human as well as animal vectors. In,
an english physician called John Snow (1854) and a German microbiologist called
Robert Koch (1884) found a relationship between polluted water and disease. Robert
Koch, has isolated the bacterium Vibrio cholera, the cause of cholera from Elbe River
water to provide the relationship.
Koch went on to formulate an established set of procedures to isolate and identify
the causative agent of a particular microbial disease. The following four steps, which
are still used today, are known as Koch’s Postulates:
Postulate 1: A specific organism must always be observed in association with the
disease.
Postulate 2: The organism must be isolated from an infected host and grown in
pure culture in the laboratory.
Postulate 3: When the organism from the pure culture is inoculated into a susceptible
host organism, it must cause the disease.
Postulate 4: The infectious organism must be re-isolated from the diseased organism
and grown in pure culture.
Self-assessment 15.1
1. What are the Koch’s Postulates?
2. Explain the theory of spontaneous generation.
15.2. Classification of diseases
Activity 15.2
Use the Knowledge gained to answer to the following questions:1. Propose two infectious diseases and for each disease, give:2. Does being healthy means just the absence of the disease? Explain.
a. their causal agents
b. causal agents’ type
c. their symptoms
d. their methods of prevention
e. Treatment
The following are the meaning of disease, signs and symptoms:– Disease is the disruption of normal body function.15.2.1. Infectious diseases
– Signs are indications of a disease that can be observed by examining the
patient.
– Symptoms are indications of disease perceive only by the patient.
The normal functioning of the body is disturbed, when the body is infected. Many
types of diseases are broadly divided into two categories: Infectious diseases andnon-infectious diseases
Infectious diseases are caused by microorganisms known as pathogens which
may include viruses, bacteria, fungi and protozoa. Those diseases are called
communicable diseases. as they can be transmitted from one person to another.
They include cholera, malaria, typhoid, HIV and AIDS…Malaria is one of the most
dangerous infectious diseases, endemic in Latin America, Africa and South-East Asia.
Some infectious diseases can also be from animals to humans.
The following are some technical terms used when discussing about infectious
disease.
– Aetiology: The study of the cause of disease.
– Epidemiology: The study of all the factors that contribute to the appearance
of a particular disease
– Causative agent: The organism which causes the disease
– Vector: An organism which carries the causative agent of the disease from
one person to another or from infected animal to human.
– Incubation period: The period of time between the original infection and the
appearance of signs and symptoms.
– Infective period: The time during which a person is capable of passing the
disease on to another person.
– Carrier: The person who has been infected but develop no signs and symptom,
the carrier can pass the disease on to another person
– Prevention: Measures taken to prevent diseases.
– Treatment: Measures taken to cure diseases Antibody: Is a protein produced
by the body’s immune system when it detects harmful substances called
antigen.
– Antigen: Is any substance that causes your immune system to produce
antibodies against it.
– Host: A host can be anything living organism ion which pathogens can survive
– Hygiene: Practices that help to maintain health and prevent the spread of
diseases
– Immunity: Is the ability of the body to resist to infections.
a. Important advances in the work against infectious disease
Table 15.1: The chronology of some of the most important advances in the work against
infectious disease
b. Some groups of communicable diseases
– Bacterial diseases: these are diseases caused by bacteria. They include
cholera, typhoid, tetanus, tuberculosis, etc.
– Viral diseases: these are diseases caused by viruses. They include AIDS, polio,
measles, Ebola, etc.
– Protozoan diseases: these are diseases caused by protozoa. They include
malaria, sleeping sickness, trichomoniasis, etc.
– Fungal diseases: these are diseases caused by fungi. They include candidiasis,
athlete’s foot, ring worms, etc.
– Worm diseases: these are diseases caused by worms. They include
elephantiasis, bilharzias, etc.
– Sexually transmitted diseases: these are diseases transmitted through
sexual contact. They include HIV-AIDS, syphilis, gonorrhea, etc.
c. Transmission of infectious diseases
Pathogens can spread when you have direct contact with an infected person. For
example, if you have contact with the person’s blood, body fluids or open wounds.
Pathogens can also be spread through contaminated food, water or air. Infectedanimals can spread pathogens to people.
The following conditions lead to the spread of an infectious disease:
– A pathogen which causes the disease.
– A source which is an infected organism.
Mode of transmission a pathogen must be able to enter the body of the new host
to cause an infection. Infectious diseases follow a pattern of development from the
time of infection. The pattern of development has five distinct periods, as described
in table below:Table 15.2: The pattern of development’s distinct periods for infectious diseases
d. Epidemiology
The study of patterns of disease and of the various factors that affect the spread of
disease is called epidemiology.
Epidemiologists try to discover the factors that cause a disease and develop methods
to prevent its spread. The main clue they use come from data about the number of
people in a particular area affected by specific diseases, and the number of death
The data are commonly expressed as incidence or morbidity and mortality rates.
The incidence rate is the number of new cases of disease in a given populationoccurring during a specific period (a week, month or a year). It is calculated as:
To find how many cases of a disease are new, this calculation requires information
about the prevalence rate. This is the total number of individuals infected in a
population at any one time.
The mortality rate of a disease may be estimated for a whole population irrespectiveof whether they have the disease or not.
It may be calculated by using only those people who have disease
To make fair comparisons between different populations with the same disease,
epidemiological information is usually adjusted. For example, the mortality rate
among those with a particular disease is usually expressed as a percentage or ratio
per year. Hence, if in one year 7500 people in a given area die as a result of AIDS and
the total number of population infected was 30 000, the mortality rate would be25% for the rate.
Epidemiological studies are used to identify whether a disease is endemic, epidemic,
or pandemic:
– Endemic disease is a disease that is always present in a people e.g. malaria in
tropical Africa.
– Epidemic disease is a disease that spreads rapidly, suddenly, and unexpectedly
to affect many people. e.g. cholera in refugees’ camp. Pandemic disease is a
disease that affects people over very large area, such as a continent or eventhe whole world e.g. AIDS and TB are pandemic at present
15.2.2. Non-infectious diseases
These diseases are also called non-communicable diseases. They cannot be
transmitted from one person to other examples: albinism, kwashiorkor, cancer,diabetes, etc
Table 15.3: Six groups of non-communicable diseases
Lesson self-assessment 15.2
1.Answer by true or false
a. Epidemic disease is a disease that is always present in population.
b. The diseases that transmitted among people by pathogens are called
transmissible diseases
c. The study of patterns of disease and of the various factors that affect the
spread of disease is called epidemiology.
d. Cholera is infectious disease
e. Malaria is non-infectious disease whose vector is mosquito.2. Distinguish between morbidity and mortality
15.3. Common infectious diseases
Activity 15.3
Choose in the following list the infectious diseases and explain why:
Cholera, typhoid, Alcoholism, tetanus, tuberculosis, AIDS, Haemophilia, polio,
measles, Ebola, malaria, Anorexia, obesity, sleeping sickness, trichomoniasis,
sickle-cell anemia, candidiasis, athlete’s foot, ring worms, elephantiasis, bilharzias,syphilis, gonorrhea, cystic fibrosis, Arthritis, Anorexia, schizophrenia.
15.3.1. Measles
Measles is a contagious acute viral disease with symptoms that include a bright red
rash of small spots that spread to cover the whole body. Small white spots, known
as Koplik’s spots, appear in the mouth on the inside of the cheeks a few days beforethe rash appears and can be used in diagnosis.
Table15.4: The features of measles.
Failure to eradicate measles
– Incubation period is short hence it is difficult to identify and isolate before
they become infectious
– It is transmitted through a carrier mother to healthy children hence it is hard
to eradicate.
– It targets young children who like playing together. This makes ease the spreadof the disease.
15.3.2. Typhoid
a. Causal agent of typhoid
Typhoid is waterborne disease caused by Salmonella typhus, a Gram negative
bacterium. The bacteria are derived from the feces of a patient. It has high infectivity
as low dosage of organisms is only needed for typhoid to spread. Common sourcesof typhoid infection are contaminated water, milk and food.
b. Development of typhoid illness
The incubation period is of ten days. After this time, the germs enter the bloodstream
and the patient develops the following symptoms: Headache, Muscular pains, Fever
reaching its peak after about 1 week, faint rash may appear, diarrhea in the second
week, mental confusion, etc. The third week shows the peak of the illness and thepatient may die if not treated.
c. Treatment and prevention of typhoid
The disease had a 20% fatality rate before the use of antibiotics. Chloramphenicol
and Ampicillin are effective and reduce fatality rate from 1 up 5%. Today, Ciprofloxine
is used as another antibiotic. The two most important preventive measures are;
proper treatment of sewage and disinfection of water supplies. Hygienic measures
in the food trade and at home, and control of flies, which can transfer fecal materialto food. Vaccine is formed by a polysaccharide from the capsule of the bacteria.
15.3.3. Cholera.
Cholera is a good example of a waterborne disease. It is endemic in parts of Asia,
particularly India. The organism which causes cholera is a comma shaped motile
bacterium called Vibrio cholerae.a. Transmission and symptoms of cholera
The main source of infection is water contaminated by feces with Vibrios. It is
estimated that only about one infected person in 50 develops the disease, the rest
being carriers. Drinking contaminated water, or washing food or utensils in it, is the
most common means of transmission. Direct contamination of food with feces as a
result of poor hygiene is also possible, house flies being the main vector in this last
case.
b. Signs and symptoms of cholera
Vibrio cholerae multiply in the intestine, releasing a powerful toxin which results inviolent inflammation of the intestine and production of the watery diarrhea.
The main sign of the disease is severe diarrhea due to irritation of the bowel by toxins
from the Vibrios. The liquid of the feces is so profuse and cloudy like “rice water”.
Abdominal pain and vomiting are also common. Dehydration is rapid and quickly
results in death unless rehydration treatment is given. Fever is absent; in fact, theskin feels deathly cold and often damp.
Table15.5: The features of cholera.
c. Treatment of cholera
The primary cause of death from cholera is dehydration i.e. loss of water with its
minerals salts. For that, it is obligatory to rehydrate with oral serum which contain
mineral salts and sugar.
The loss fluid may be replaced by administration of a drip food into a vein.
Various antibiotics, such as tetracycline’s and chloramphenicol, are used to treatcholera. Chloramphenicol is effective against tetracycline-resistant Vibrios.
d. Prevention of cholera
– Use clean drinking water,
– Proper treatment of sewage and sanitation
– High standards of public and personal hygiene, particularly in relation to food
(such as washing hands after defecation)
– Health education
– Vaccination is recommended for people visiting areas where cholera is
endemic and for those living in such areas. But the vaccine lasts few months.– Isolation of patients and hygienic disposal of feces and vomit from patients.
e. Failure to eradicate cholera
– Vaccination is not very effective
– It is a waterborne disease i.e. transmitted through contaminated water– Poor sanitation condition in camps.
15.3.4. Tuberculosis (T.B)
TB spreads when infected people with the active form of the illness cough or sneeze
and the bacteria are carried in the air in tiny droplets of liquid.
a. Causal agent of tuberculosis
Tuberculosis is caused by bacterium called Mycobacterium tuberculosis, first
discovered by Robert Koch in 1882. It is sometimes referred to as the tubercle bacillus,
bacilli being rod-shaped bacteria. The common form is pulmonary T.B which infectsthe lungs, although other organs may be affected.
Two strains of the bacterium may cause the disease, the human and the bovine
forms. The latter can be present in cattle and can enter the milk of cows. It is veryresistant and can remain alive for long time in milk products as well as in durst.
b. Transmission of tuberculosis
Tuberculosis is mainly airborne disease. The infection is done through the droplets
from the patient. It is much less infectious as it requires prolonged contact between
people, poor ventilation and overcrowded living conditions. In addition, TB is an
opportunistic infection, striking many people with a depressed immunity.
c. Signs and symptoms of tuberculosis
The disease is frequently characterized by vague symptoms such as: loss of appetite;
loss of weight; excessive sweating; coughing, appearance of blood in the sputum,
pains on the chest, shortness of breath (case of lung tuberculosis).
d. Treatment and prevention of tuberculosis
Vaccine against the disease has been developed by Albert Calmette and
Camileguerin). Antibiotics such as rifampicin, isoniazid and streptomycin are usedto treat tuberculosis.
e. Failure to eradicate tuberculosis
– Patients can carry pathogen and infection without showing symptoms.
Therefore, they are difficult to identify due to a long period of incubation
– Germs of tuberculosis can survive longer in the house dust
– The disease is related to poverty where many people share the same room and
have malnutrition.
– The disease is associated with AIDS that reduced the body immunity
– Long period of treatment (6-8 moths), hence patients give up when not yet
fully healed. The pathogens then form endospores that resists to medicines.
– The disease is also spread through milk from infected animals. Tuberculosis isan airborne disease i.e. spread in air
15.3.5. Malaria.
a. Causal agent
Malaria is caused by four species of plasmodium: Plasmodium falciparum, P. vivax, P.
ovale, and P. Malariae.The parasite is transmitted by the bite of female mosquitoes
(the vector) belonging to the genus Anopheles.
b. Symptoms
Malaria is characterized by severe chills, fever, sweating, fatigue and great thirst.
Victims die of anemia, kidney failure or brain damage.
c. Occurrence of malaria
The disease now occurs in tropical and subtropical regions of the world, and its
distribution is limited by conditions of the development of the mosquito vectorsuch as temperature and altitude.
Malaria is endemic in tropics because:
– Tropical climate provides the best breeding and living conditions for the
Anopheles mosquito which transmits malaria
– The Anopheles cycle requires areas of stagnant water, common within tropics
– In the tropical areas, there is presence of bushes or abundant vegetation which
makes suitable habitat for mosquitoes
– Plasmodium needs temperature in excess of 20ᵒC for it to complete its cyclewithin the mosquito.
Table15.7: The features of malaria.
d. Eradication and prevention of malaria
– Drainage of stagnant water: The larval stages of the mosquito live in stagnant
water, so drainage removes breeding sites.
– Destruction of the adult mosquitoes by spraying insecticide.
– Clean bushes nearest houses where mosquitoes lay eggs
– Sleeping under mosquito net during the night
e. Failure to eradicate malaria
– There is no effective vaccine against malaria
– The pathogens are transmitted by mosquitoes which are difficult to eradicate.
– The plasmodium has become resistant to different anti-malarial drugs
– Ignorance of some people toward the disease and how it is spread.
15.3.6. Smallpox
a. Cause of smallpox
Smallpox was a horrible viral disease caused by Variola virus (DNA virus), a pox virus.
It was a highly infectious disease transmitted by direct contact and it affects therespiratory passage.
b. Signs and Symptoms of smallpox
The following are Signs and Symptoms of smallpox:
– Obvious symptoms of the disease were red sports on the face, trunk, and
extremities that change to pea-sized blisters and became filled with pus. Highfever and generalized aching.
c. Modes of transmission
This disease spread through droplet infection (contagion possible via wounds in
skin, clothing, bedding and dressing)
d. Prevention and treatment
Large populations were vaccinated through Ring vaccination and people with the
disease were isolated.
The eradication of Smallpox was successful because:
– The smallpox virus is stable. so the same vaccine could be used
– The smallpox virus does not linger in the body after infection, nor does it infect
other animals, so it cannot remain hidden anywhere.
– The vaccine used was highly effective and easy to administer by scratching
technique.– It was easy to identify people with the disease.
Table15.8: The features of Smallpox
15.3.7. Tinea
Tinea is a skin infection due to a fungus. Often, there are several patches of ringworm
on the skin at once. Tinea is also known as Ringworm.
a. Cause of Tinea
– Tinea is caused by a tiny fungus known as dermatophyte. These tiny organisms
normally live on the superficial skin surface, and when the opportunity is right,
they can induce an infection.
– The disease can also be acquired by person-to-person transfer usually via
direct skin contact with an infected individual. Animal-to-human transmission
is also common.
– Ringworm commonly occurs on pets (dogs, cats) and the fungus can be
acquired while petting or grooming an animal.
– Ringworm can also be acquired from other animals such as horses, pigs, ferrets
and cows.
– The fungus can also be spread by touching inanimate objects like personal
care products, bed linen, combs, athletic gear, or hair brushes contaminated
by an affected person.
Individuals at high risk of acquiring ringworm include those who:
– Sweat excessively, as sweat can produce a humid wet environment where
the pathogenic fungi can thrive.
– Wear tight, constrictive clothing with poor aeration.
– Have a weakened immune system
– Live in crowded, humid conditions.– Participate in close contact sports like soccer, rugby
b. Sign and symptoms of Tinea
The following are Sign and symptoms of Tinea:
– Enlarging raised red rings with a central area of clearing (ringworm).
– The edge of the rash appears elevated and is scaly to touch.
– Sometimes the skin surrounding the rash may be dry and flaky.
– There will be hair loss in areas of the infection.c. Diagnosis
Superficial scrapes of skin examined under a microscope may indicate the presence
of a fungus. Diagnostic method called KOH Test is used, where the skin scrapings
are placed on a slide and immersed on a drop of potassium hydroxide solution
to dissolve the keratin on the skin scrapings thus leaving fungal elements such
as hyphae, septate or yeast cells viewable. If the skin scrapings are negative and
a fungus is still suspected, the scrapings are sent for culture. Because the fungus
grows slowly, the culture results do take several days to become positive.
d. Prevention
Basic prevention measures include:
– Serious washing of hands after handling animals, soil, and plants.
– Avoiding touching characteristic lesions on other people.
– Put on loose-fitting clothes.
– Promoting good hygiene when participating in sports that involve physicalcontact with other people.
e. Treatment
Application of topical antifungals creams to the skin. In extensive or difficult
cases, systemic treatment with oral medication may be required. Among theavailable prescription drugs are tolnaftate, terbinafine, naftifine, itraconazole.
15.3.8. Hookworm
Hookworm is a humans’ intestinal parasite. The adult worms and their larvae can
cause intestinal disease in which they live.
a. Cause of hookworm disease
The hookworm is caused by two main species of hookworm infecting humans which
are: Ancylostoma duodenale and Necatora mericanus
b. Method of transmission
If an infected person defecates near bushes, in a garden, or field, or if the feces from
an infected person are used as fertilizer, eggs are deposited on soil. They can then
mature and hatch, releasing larvae (immature worms). The larvae mature into a form
that can penetrate the skin of humans. Hookworm infection is transmitted primarily
by walking barefoot on contaminated soil.
c. Signs and symptoms of hookworm
– Itching and a localized rash are often the first signs of infection. These
symptoms occur when the larvae penetrate the skin.
– A person with a light infection may have no symptoms but a person with a
heavy infection may experience abdominal pain, diarrhea, loss of appetite,
weight loss, fatigue and anemia (pale skin etc.) and protein deficiency caused
by blood loss, constipation, congestive heart failure, excessive coughing
during larvae migration, stomach or chest pain, vomiting, weight loss.
– The physical and cognitive growth of children can be affected. There is a
decreased rate of growth and mental development in children (caused by
protein and iron deficiency)
d. Diagnostic method
Taking a stool sample and using a microscope to look for the presence of hookworm
eggs.
e. Prevention of hookworm
Avoid walking barefoot in areas where hookworm is common and where there may
be fecal contamination of the soil.
Avoid skin-to-soil contact and ingesting such soil.
Avoid defecating outdoors or using human feces as fertilizer, and by effective sewage
disposal systems.
f. Treatment for hookworm
Hookworm infections are generally treated for 1-3 days with medication prescribed
by your health care provider. The drugs are effective and appear to have few side
effects. Iron supplements may be prescribed if you have anemia.
g. Preventive treatment
– In developing countries, groups at higher risk for soil-transmitted infections
Biology Senior Four Student’s Book 257
are often treated without a prior stool examination. Treating in this way is
called preventive treatment.
– School-age children are often treated through school-health programs and
preschool children and pregnant women at visits to health clinics.h. Life cycle of Hookworm
Self-assessment 15.3
1. Which of the following diseases is transmitted by an insect vector?
a. Cholera
b. HIV/AIDS
c. Malaria
d. TB
2. What are the ways in which cholera is transmitted from person to person?
3. Explain why there is such a high risk of cholera following natural disasters such
as earthquakes, hurricanes, typhoons and floods.
4. Explain why there is a high death rate from TB in countries with a high proportion
of the population who are HIV-positive.
5. TB is an opportunistic infection. Why?
6. Describe how malaria is transmitted.
15.4. Health and community: criteria for good housing
Activity 15.4
Housing quality is associated with morbidity from different factors. State any
three factors
Housing refers to houses or buildings, accommodation of people. It is an importantdeterminant of health, and substandard housing is a major public health issue.
The public health community is aware of the importance of social determinants
of health (including housing) in recent years. Yet defining the role of public health
practitioners in influencing housing conditions has been challenging. Responsibility
for social determinants of health is seen as lying primarily outside the scope of public
health. The quality and accessibility of housing is, however, a particularly appropriate
area for public health involvement.
An evolving body of scientific evidence demonstrates solid relations between
housing and health. The public health community is developing, testing, and
implementing effective interventions that yield health benefits through improved
housing quality.
Criteria for good housing
– Good housing must be well equipped.
– Good housing must be well localized
– Water and electricity
– Big size and ventilated
An increasing body of evidence has associated housing quality with morbidity from
infectious diseases, chronic illnesses, injuries, poor nutrition, and mental disorders.
Self-assessment 15.4
What measures are taken by Rwanda government to ensure high quality of
housing conditions?
15.5. Public health services
Activity 15.51. Suppose that you are one of Rwandans who have food industry in our15.5.1. Food inspection requirement
country, and you expect your production to be inspected. Outline the main
requirements for good production to be inspected?
2. Clean water is good for health. Discuss the ways you would use to obtainclean water at home.
a. Food inspection services
Food inspections services help to let you have a complete check of your running
production in factories or across the country. An inspector performs a random
selection checking on quantity, packing, labeling, dimension, weight and visual
aspects. Inspection allows to spot inconsistencies in your production lots before they
leave the factory: you can react timely and avoid costly rework, sorting or recalls.
15.5.2. Need for control of housing conditions
Living conditions affect people’s lives, be it at home or the workplace. Without good
living conditions, people’s health and work will be affected. Nowadays, the quality of
housing accompanied with good housing facilities is now improving.
15.5.3. Need for control of clean water.
For being healthy, only clean water must be used. Different materials are used to
clean water. They include “Sûr–eau”, heating or by using water purification etc. The
steps of water purification are: storage reservoir, aeration, filtration, disinfection,
reduction of chlorine concentration, covered service reservoir, distribution.
15.5.4. Need for control of hygiene
Many diseases can be prevented from having a damaging effect on the body by
the action of natural defenses, antibiotics or other medicines. However, there are
many steps that can be taken by individuals, and by the community as a whole,
to fight microbes even before they enter the body and cause disease. These steps
concern personal hygiene (cleanliness) and sanitation (public cleanliness involving
community efforts in disease prevention), both of which help to prevent disease.
Note that: The World of Health Organization defines health as a state of complete
physical, mental and social well-being and not merely the absence of disease and
infirmity. The responsibility for good health lies in the hands of each individual in
the community and the nation.
a. Personal hygiene– Hands frequently touch many things which may carry pathogens. They mustExercise, recreation and rest are other factors that are important in promoting health.
be always washed using a soap before preparing food, eating and after a visit
to a toilet.
– It is essential to bath frequently because sweat and oil secretions on the skin
enable bacteria and fungi to breed easily. This helps to prevent skin infections.
– Bath towels and sponges should not be shared Combs and hairbrushes should
not be shared.
– Hair should be washed frequently to avoid lice and mites. These can spread
typhus fever.
– Teeth should be cleaned at least twice a day, preferably after each meal
because the spaces between teeth where food particles are trapped provide
excellent breeding grounds for bacteria.
– Clothes would be clean and changed frequently.
– Shoes should be worn to prevent cuts and infection by hookworms.
– Finger nails and toe nails must be always kept short and clean so that they do
not provide breeding places for germs.
i. Exercise
Exercise makes the muscles strong so that they can support the body better.
It helps to get rid of excretory materials and to improve digestion.
It quickens blood circulation and improves the action of the glands and nerves.
ii. Recreation
– Gardening, playing games and reading can remove any dullness and mental
tiredness resulting from everyday work.
iii.Sleeping is the best form of rest.– Adults need about eight hours of sleep a day. A great deal of repair of wornout tissues in the body and the building up of new ones takes place whenLesson self-assessment 15.5
body rests.
– Other good personal habits include avoiding smoking, alcoholic drinks and
other drugs.
1. In which ways a personal cleanliness may be achieved.
2. How to promote a hygienic food preparation?3. Discuss about good personal Hygiene.
End of unit assessment 15
1. Answer to the following questions:a. What does the germ theory of disease mean?2. State any TWO diseases caused by:
b. State any four causes of diseases in our life.a. Bacteria
b. Protozoa
c. Microscopic fungi3. Match the following scientists with their scientific contributions:
4. List the reasons why smallpox is easier to eradicate than AIDS.
5. Suggest reason why Malaria is endemic disease in tropics.
6. Describe the biological factors that make malaria a difficult disease to
control.
7. Describe the precautions that people can take to avoid catching malaria.8. Explain what is meant by ring vaccination.