Reducing the Spread of Infectious Diseases Human activities drive emergence of disease and a variety of social, economic, political, climatic, technological, and environmental factors can shape the pattern of the disease and influence its emergence into populations. The most effective method of stemming the spread of infectious disease is through vaccination. Vaccines consist of weakened or killed microbes, or just components of a pathogen, and stimulate the body’s natural defenses—the immune system—to combat infections. Vaccination has eliminated smallpox, nearly eradicated poliovirus from much of the world, and drastically reduced the incidence of childhood infections, such as measles, mumps, and whooping cough, at least in the developed world. Influenza vaccines are available to reduce the occurrence of seasonal flu, although the shot must be given yearly due to the extreme variance of the influenza virus from season to season. Vaccines for other infectious diseases, especially HIV, still are being sought. Antibiotics are effective for many types of bacterial infections (although they are entirely useless against viruses). But increasingly, bacteria are becoming resistant to the arsenal of antibiotics at our disposal. Very few drugs work well against viruses (anti-viral drugs for influenza and HIV were discussed in the previous two slides). Anti-fungal drugs exist, but their use is limited. There are no vaccines against protozoan parasites, and other medications against them are becoming ineffective. Therefore, protection from insect vectors such as mosquitoes and control of mosquito populations are crucial strategies in containing the spread of insect-borne diseases, such as malaria. Good sanitation, water purification, hand washing, and proper cooking and storage of foods all help to reduce the prevalence of infectious disease. In cases of highly contagious, often fatal diseases, quarantine is employed as a means of preventing the spread of disease through a community. However, regardless of the disease, it is wise to limit contact with other individuals when ill. Reference Hahn, D. B., Payne, W. A., & Mauer, E. B. (2005). Focus on health (7th ed.). New York: McGraw Hill. National Institute for Allergy and Infectious Diseases. (2006). Microbes in sickness and in health. Retrieved 9-20-2006 from http://www.niaid.nih.gov/publications/microbes.htm Image Reference Gathany, J. (2003). Influenza virus vaccine, (ID# 5404). CDC. Retrieved 8-14-2006 from http://phil.cdc.gov/phil/quicksearch.asp
st. vincent Pallotti
College of Engineering
INTRODUCTION ABOUT DISEASES.
INTRODUCTION TO INFECTIOUS DISEASES.
TYPES & CAUSES OF INFECTIOUS DISEASES.
PREVENTIVE MEASURES ON INFECTIOUS DISEASES.
WHAT ARE WATER BORNE DISASES &ITS CAUSES.
EFFECTS OF WATER BORNE DISEASES ON HUMANS.
PREVENTIVE MEASURES FOR WATER BORNE DISEASES.
CAUSES OF CANCER &ITS TYPES.
EFFECTS OF CANCER ON HUMANS.
PREVENTIVE MEASURES OF CANCER
A disease is an abnormal condition
organism. It is often construed as a
medical condition associated with
specific symptoms and signs.
Any disease caused by the presence of
pathogens in the body is called an infectious
disease. The main sources of pathogens are soil,
contaminated water, and infected animals,
including other people
Infectious diseases, also known as
transmissible diseases or communicable diseases,
characteristic medical signs and/or symptoms of
disease) resulting from the infection, presence
and growth of pathogenic biological agents in an
individual host organism.
The term infectivity describes the ability of an
organism to enter, survive and multiply in the
host, while the infectiousness of a disease
indicates the comparative ease with which the
disease is transmitted to other hosts.
Infectious pathogens include some viruses,
bacteria, fungi, protozoa, multicellular
parasites, and aberrant proteins known as
Infectious diseases are sometimes called
"contagious" when they are easily transmitted
by contact with an ill person or their secretions
(e.g., influenza). Thus, a contagious disease is a
subset of infectious disease that is especially
infective or easily transmitted.
Phases of infectious diseases
Incubation period – time between infection
and the appearance of signs and symptoms.
Prodromal phase – mild, nonspecific
symptoms that signal onset of some
Clinical phase – a person experiences typical
signs and symptoms of disease.
Decline phase - subsidence of symptoms.
Recovery phase – symptoms have
disappeared, tissues heal, and the body
Some infectious diseases
Diseases caused by
ingestion of water contaminated by
human or animal excrement, which
contain pathogenic microorganisms
that means any disease which is
transported and supported by water
is called water born diseases
eg. Include cholera,
typhoid, amoebic and bacillary
dysentery and other diarrheal
In addition, water-borne disease can be
caused by the pollution of water with
chemicals that have an adverse effect on
Nitrates from fertilizers
Carcinogenic pesticides (DDT)
Lead (from pipes)
Effects of Water-borne diseases
~80% of infectious diseases
> 5 million people die each year
> 2 million die from water-related
Most of those dying are small children
Lost work days
Missed educational opportunities
Official and unofficial healthcare costs
Draining of family resources
COMMON TYPES OF WATER-BORNE
BOTULISM- Clostridium botulinum .Bacteria can enter
an open wound from contaminated water sources. Can
enter the gastrointestinal tract by consuming
contaminated drinking water or (more commonly) food.
Dry mouth, difficulty swallowing, muscle
difficulty breathing,vomiting and
diarrhea. Death is usually caused
DYSENTRY-Caused by a number of species in the
generaShigella andSalmonella with the most common
beingShigella dysenteriae . Frequent passage
Hepatitis A - Hepatitis A virus (HAV).Can manifest
itself in water (and food)Symptoms are
(no chronic stage to the virus) and
fever, abdominal pain, nausea,
Cholera is a disease caused by bacteria that produce a
watery diarrhea that can rapidly lead to dehydration.
Cholera symptoms and signs include a rapid onset of
copious, smelly diarrhea that resembles rice water and
may lead to signs of dehydration.
Cholera is most frequently transmitted by water sources
contaminated with the causative bacterium Vibrio cholera
It can take anywhere from a few hours to 5 days for
symptoms to appear after infection. Symptoms typically
appear in 2-3 days. For example, fowl or chicken cholera
is a disease that can rapidly kill chickens and other
disease characterized by profuse watery diarrhea,
vomiting, and leg cramps,nausia. In these people, rapid
loss of body fluids leads to dehydration and shock.
Without treatment, death can occur within hours.
Outbreaks occur when there are disasters or other
reasons for a loss of sanitary human waste disposal and
the lack of safe fluids and foods for people to ingest.
Haiti, a country that had not seen a cholera outbreak in
over 50 years, had such circumstances develop in 2010
after a massive earthquake destroyed sanitary facilities
and water and food treatment facilities for many
Haitians. V. cholera bacteria eventually contaminated
primary water sources, resulting in over 530,000 people
diagnosed with cholera that resulted in over 7,000 deaths
Control & Prevention
Improvements in habitation and general
Higher education training in water-related issues
Public health infrastructure
Standardized surveillance of water-borne disease
Guidelines must be established for investigating
and reporting water-borne diseases
Control & Prevention
Communication and the Media
Impacts at all levels
Very powerful, when others fail
Avoid contacting soil that may be contaminated
with human feces.
Do not defecate outdoors.
Dispose of diapers properly.
Wash hands with soap and water before handling
When traveling to countries where sanitation and
hygiene are poor, avoid water or food that may
Wash, peel or cook all raw vegetables and fruits
Cancer is a term used to described large
group of diseases that are characterized by a
cellular malfunction. Healthy cell are programmed to
“know what to do and when to do it”. Cancerous cells
do not have this programming and therefore grow
and replicate out of control. They also serve no
physiological function. These cells are now termed a
Cancer is one of the most common
diseases in the developed world:
1 in 4 deaths are due to cancer
1 in 17 deaths are due to lung cancer
Lung cancer is the most common cancer
Breast cancer is the most common cancer
There are over 100 different forms of
The division of normal cells is precisely controlled.
New cells are only formed for growth or to replace
Cancerous cells divide repeatedly out of control
even though they are not needed, they crowd out
other normal cells and function abnormally. They
can also destroy the correct functioning of major
Causes of Cancer
Cancer arises from the mutation of a
Mutated genes that cause cancer are
It is thought that several mutations need
to occur to give rise to cancer
Cells that are old or not functioning
properly normally self destruct and are
replaced by new cells.
However, cancerous cells do not self
destruct and continue to divide rapidly
producing millions of new cancerous cells.
Causes of Cancer
A factor which brings about a mutation is
called a mutagen.
A mutagen is mutagenic.
Any agent that causes cancer is called a
carcinogen and is described as
So some mutagens are carcinogenic.
The Development of
Within every nucleus of every one of the
human body's 30 trillion cells exists
DNA, the substance that contains the
information needed to make and control
every cell within the body. Here is a
close-up view of a tiny fragment of DNA.
1. DNA of a normal cell
This piece of DNA is an exact copy of the
DNA from which it came. When the parent
cell divided to create two cells, the cell's
DNA also divided, creating two identical
copies of the original DNA.
2. Mutation of DNA
Here is the same section of DNA but from another cell.
If you can imagine that DNA is a twisted ladder, then
each rung of the ladder is a pair of joined molecules, or
a base pair. With this section of DNA, one of the base
pairs is different from the original.
This DNA has suffered a mutation, either through
miss-copying (when its parent cell divided), or through
the damaging effects of exposure to radiation or a
3. Genetically altered cell
Body cells replicate through mitosis, they respond
to their surrounding cells and replicate only to
replace other cells. Sometimes a genetic mutation
will cause a cell and its descendants to reproduce
even though replacement cells are not needed.
The DNA of the cell highlighted above has a
mutation that causes the cell to replicate even
though this tissue doesn't need replacement cells
at this time or at this place.
4. Spread and second mutation
The genetically altered cells have, over time,
reproduced unchecked, crowding out the surrounding
normal cells. The growth may contain one million cells and
be the size of a pinhead. At this point the cells continue
to look the same as the surrounding healthy cells.
After about a million divisions, there's a good
chance that one of the new cells will have mutated
further. This cell, now carrying two mutant genes, could
have an altered appearance and be even more prone to
5. Third mutation
Not all mutations that lead to cancerous cells result in
the cells reproducing at a faster, more uncontrolled rate.
For example, a mutation may simply cause a cell to keep
from self-destructing. All normal cells have surveillance
mechanisms that look for damage or for problems with their
own control systems. If such problems are found, the cell
Over time and after many cell divisions, a third mutation
may arise. If the mutation gives the cell some further
advantage, that cell will grow more vigorously than its
predecessors and thus speed up the growth of the tumour.
6. Fourth mutation
The new type of cells grow rapidly, allowing
for more opportunities for mutations. The
next mutation paves the way for the
development of an even more aggressive
At this point the tumour is still contained.
7. Breaking through the membrane
The newer, wilder cells created by another mutation
are able to push their way through the epithelial
tissue's basement membrane, which is a meshwork of
protein that normally creates a barrier. The invasive
cells in this tumour are no longer contained.
At this point the cancer is still too small to be
Often during the development of earlier stages of the
tumour, or perhaps by the time the tumour has broken
through the basement membrane (as pictured above),
angiogenesis takes place. Angiogenesis is the recruitment
of blood vessels from the network of neighbouring vessels.
Without blood and the nutrients it carries, a tumour
would be unable to continue growing. With the new blood
supply, however, the growth of the tumour accelerates; it
soon contains thousand million cells and, now the size of a
small grape, is large enough to be detected as a lump.
9.Invasion and dispersal
The tumour has now invaded the tissue beyond the
Individual cells from the tumour enter into the
network of newly formed blood vessels, using these
vessels as highways by which they can move to other
parts of the body. A tumour as small as a gram can
send out a million tumour cells into blood vessels a
10. Tumour cells
travel - metastasis
What makes most
tumours so lethal is
their ability to
metastasize -- that is,
establish new tumour
sites at other locations
throughout the body.
Metastasis is now
underway, as tumour
cells from the original
cancer growth travel
throughout the body.
Most of these cells will
die soon after entering
the blood or lymph
To form a secondary tumour, a tumour cell needs
to leave the vessel system and invade tissue. The cell
must attach itself to a vessel's wall. Once this is
done, it can work its way through the vessel and enter
Although perhaps less than one in 10,000 tumour
cells will survive long enough to establish a new
tumour site, a few survivors can escape and initiate
new colonies of the cancer.
Types of cancer
Blood Cancer: The cells in the bone marrow that give rise to
red blood cells, white blood cells, and platelets can sometimes
become cancerous. These cancers are leukemia or lymphoma.
Bone Cancer: Bone cancer is a relatively rare type of cancer
that can affect both children and adults, but primarily affects
children and teens.
Brain Cancer: Brain tumors can be malignant (cancerous) or
benign (non-cancerous). They affect both children and adults.
Malignant brain tumors don't often spread beyond the brain.
However, other types of cancer have the ability to spread to
Breast Cancer: Breast cancer is a common type of cancer that
affects women and much less commonly, men. More than
200,000 women are diagnosed with breast cancer.
Types of cancer
Digestive/Gastrointestinal Cancers This is a broad category of cancer
that affects everything from the esophagus to the anus. Each type is
specific and has its own symptoms, causes, and treatments.
Eye Cancer: Like other organs in the human body, the eyes are
vulnerable to cancer as well. Eye cancer can affect both children and
Endocrine Cancers: The endocrine system is an instrumental part of the
body that is responsible for glandular and hormonal activity. Thyroid
cancer is the most common of the endocrine cancer types and generally,
the least fatal.
Genitourinary Cancers: These types of cancer affect the male genitalia
and urinary tract.
Gynecologic Cancers: This group of cancer types affect the organs of
the female reproductive system. Specialized oncologists called
gynecologic oncologists are recommended for treating gynecologic
Types of cancer
Head and Neck Cancer: Most head and neck cancers affect moist
mucosal surfaces of the head and neck, like the mouth, throat, and nose.
Causes of head and neck cancer vary, but cigarette smoking plays a role.
Respiratory Cancers: Cigarette smoking is the primary cause for
cancer affecting the respiratory system. Exposure to asbestos is also a
Skin Cancers: Non-melanoma skin cancer is the most common type of
cancer among men and women. Exposure to the UV rays of the sun is the
primary cause for non-melanoma skin cancer and also melanoma.