1. Kissing Disease – Mononucleosis

1. Kissing Disease – Mononucleosis
What Is Mono?
Sometimes called "mono" or "the kissing disease," is an infection usually
caused by the Epstein-Barr virus (EBV). EBV is very common, and many
people have been exposed to the virus at some time in childhood.
Not everyone who is exposed to EBV develops the symptoms of mono,
though. As with many viruses, it is possible to be exposed to and
infected with EBV without becoming sick.
People who have been infected with EBV will carry the virus for the rest of their lives — even if
they never have any signs or symptoms of mono.
Contagiousness: How Do People Get Mono?
One common way to "catch" mono is by kissing someone who has been infected, which is how the
illness got its "kissing disease" nickname. If
you have never been infected with EBV,
kissing someone who is infected can put
you at risk for getting the disease.
But what if you haven't kissed anyone? You
can also get mononucleosis through other
types of direct contact with saliva (spit)
from someone infected with EBV, such as
by sharing a straw, a toothbrush, or an
eating utensil.
Some people who have the virus in their bodies never have any symptoms, but it is still possible for
them to pass it to others. Experts believe that EBV can even spread from people who had the virus
months before.
Symptoms
They begin to appear 4 to 7 weeks after infection with the virus. Signs that you may have mono
include:
• headaches
• constant fatigue
• fever
• sore muscles
• sore throat
• larger-than-normal liver
• loss of appetite
• abdominal pain
• swollen lymph nodes (glands
located in your neck, underarms, and groin)
Treatment
There is no cure for mononucleosis. But the good news is that even if you do nothing, the illness
will go away by itself, usually in 3 to 4 weeks. Because mono is caused by a virus, antibiotics such
as penicillin won't help unless you have an additional infection like strep throat. The best
treatment is to get plenty of rest, especially during the beginning stages of the illness.
2.
Polio
Background
Polio (also called poliomyelitis) is a contagious, historically
devastating disease that was virtually eliminated from the
Western hemisphere in the second half of the 20th century.
Although polio has plagued humans since ancient times, its
most extensive outbreak occurred in the first half of the 1900s
before the vaccination, created by Jonas Salk, became widely
available in 1955.
At the height of the polio epidemic in 1952, nearly 60,000
cases with more than 3,000 deaths were reported in the United States alone.
Contagiousness
Polio is transmitted primarily through the ingestion of material
contaminated with the virus found in stool (poop). Not washing hands
after using the bathroom and drinking contaminated water were
common culprits in the transmission of the disease.
Signs and Symptoms
Polio is a viral illness that, in about 95% of cases, actually produces no
symptoms at all (called asymptomatic polio). In the 4% to 8% of cases in
which there are symptoms (called symptomatic polio), the illness
appears in three forms:
• a mild form called abortive polio (most people with this form of polio may not even
suspect they have it because their sickness is limited to mild flu-like symptoms such as mild
upper respiratory infection, diarrhea, fever, sore throat, and a general feeling of being ill)
• a more serious form associated with aseptic meningitis called nonparalytic polio (1% to 5%
show neurological symptoms such as sensitivity to light and neck stiffness)
• a severe, debilitating form called paralytic polio (this occurs in 0.1% to 2% of cases)
People who have abortive polio or nonparalytic polio usually make a full recovery. However,
paralytic polio, as its name implies, causes muscle paralysis - and can even result in death. In
paralytic polio, the virus leaves the intestinal tract and enters the bloodstream, attacking the
nerves (in abortive or asymptomatic polio, the virus usually doesn't get past the intestinal tract).
The virus may affect the nerves governing the muscles in the limbs and the muscles necessary for
breathing, causing respiratory difficulty and paralysis of the arms and legs.
Treatment / Prevention
In the height of the polio epidemic, the standard treatment involved placing a patient with
paralysis of the breathing muscles in an "iron lung" - a large machine that actually pushed and
pulled the chest muscles to make them work. The damaged limbs were often kept immobilized
because of the confinement of the iron lung. In countries where polio is still a concern, ventilators
and some iron lungs are still used.
In the United States, it's currently recommended that children have four doses of inactivated polio
vaccination (IPV) between the ages of 2 months and 6 years.
By 1964, the oral polio vaccine (OPV), developed by Albert Sabin, had become the recommended
vaccine. OPV allowed large populations to be immunized because it was easy to administer, and it
provided "contact" immunization, which means that an unimmunized person who came in contact
with a recently immunized child might become immune, too. The problem with OPV was that, in
very rare cases, paralytic polio could develop either in immunized children or in those who came in
contact with them.
3.
The Common Cold (Rhinovirus)
Background
A cold is an infection of the upper respiratory system. This
just means it affects the nose, throat, and ears. A cold
virus gets inside your body and makes you sick. There are
over 200 viruses that cause colds. The rhinovirus is the
most common cold virus, but there are more than 200
viruses that cause colds. Because there are so many, there
isn't a vaccination, or shot, to prevent you from getting
colds.
Contagiousness: How Do People Catch Colds?
Mucus is the wet, slimy stuff inside the nose. When someone sneezes or coughs, mucus drops float
in the air. Breathing in these droplets can spread a cold from one person to another.
You can also catch a cold if you touch your eyes or nose after
handling something with cold viruses on it. Video games, the doors
at the mall, and your school desk are all hot spots for viruses. So be
sure to wash your hands regularly.
Getting a cold works like space travel - the virus actually has docking
points that stick to the inside of your nose - just like a small
spaceship attaching to a mother ship! The virus takes over the cells
lining the nose and begins creating more viruses.
White blood cells charge to the nose's rescue and cause cold
symptoms, while also killing the virus that caused the cold. Runny
noses and sneezing actually help to prevent viruses from invading
other parts of your body.
You sneeze because your nerves detect the irritation in your nose and
get the lungs to push a blast of air out through your nose and mouth.
Symptoms
Once you've been in contact with a cold virus, it takes 2 to 3 days for cold symptoms to begin. If
you have some of the following symptoms, you probably have a cold:
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low fever (100 to 101 degrees Fahrenheit or 37.2 to 37.8 degrees Celsius)
body chills
itchy or sore throat
sneezing, runny nose, and watery eyes
coughing
feeling tired and not hungry
congestion (when your nose is stuffy and it's hard to breathe)
4.
HIV (Human Immunodeficiency Virus)
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At the end of 2007, there were 2.5 million
children living with HIV around the world.
420,000 children became newly infected with
HIV in 2007.
Of the 2.1 million people who died of AIDS
during 2007, more than one in seven were
children. Every hour, around forty children die
as a result of AIDS.
Background
HIV stands for Human Immunodeficiency Virus. This is the virus that causes AIDS (Acquired
Immunodeficiency Syndrome). Every person has an immune system in their body which fights
infection and disease. For someone with HIV, the virus locates certain crucial immune system white
blood cells called T-cells or CD-4 cells, and destroys them. Thus, an HIV infected person ultimately
ends up with a compromised immune system that is unable to ward off illnesses, bacteria, viruses,
and diseases.
As of January 2006, the Joint United Nations Programme
on HIV/AIDS (UNAIDS) and the World Health Organization
(WHO) estimate that AIDS has killed more than 25 million
people since it was first recognized on June 5, 1981,
making it one of the most destructive epidemics in
recorded history. In 2005 alone, AIDS claimed an
estimated 2.4–3.3 million lives, of which more than
570,000 were children.
Contagiousness
HIV is present in the blood and genital secretions of virtually all individuals infected with HIV,
regardless of whether or not they have symptoms. The spread of HIV can occur when these
secretions come in contact with tissues such
as those lining the vagina, anal area, mouth,
or eyes (the mucus membranes), or with a
break in the skin, such as from a cut or
puncture by a needle. The most common ways
in which HIV is spreading throughout the world
include sexual contact, sharing needles, and
by transmission from infected mothers to their
newborns during pregnancy, labor (the
delivery process), or breast-feeding.
Symptoms
During this period of time shortly after infection, more than 50% of
those infected will experience a "flu-like" or “infectious mono-like”
illness for up to several weeks. This illness is considered the stage of
primary HIV infection. The most common symptoms of primary HIV
infection are:
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Swollen lymph nodes — often one of the first signs of HIV
infection
Diarrhea
Weight loss
Fever
Cough and shortness of breath
Once HIV can be diagnosed as AIDS (by either a CD4 cell count of 200 or less or becoming infected
by a certain disease, like pneumonia), the following symptoms may be present:
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Soaking night sweats
Shaking chills or fever higher than 100 F for several weeks
Dry cough and shortness of breath
Chronic diarrhea
Persistent white spots or unusual lesions on your tongue or in your mouth
Headaches
Blurred and distorted vision
Weight loss
The time from HIV infection to the development of AIDS varies. Some people develop symptoms,
signaling the complications of HIV that define AIDS, within 1 year of infection. Others, however,
remain completely asymptomatic after as many as 20 years. The average time for progression from
initial infection to AIDS is 8 to10 years. The reason why different people experience clinical
progression of HIV at different rates remains an area of active research.
Treatment
At this time, there is NO cure for
AIDS, but medications are effective in
fighting HIV and its complications.
Treatments are designed to reduce
HIV in your body, keep your immune
system as healthy as possible and
decrease the complications you may
develop.
HIV Life Cycle
5. Chicken Pox
Background
Chickenpox is caused by a virus called varicella zoster. People who get the virus often develop a
rash of spots that look like blisters all over their bodies. The blisters are small and sit on an area
of red skin that can be anywhere from the size of a pencil eraser to the size of a dime. In the U.S.,
55 percent of chickenpox deaths are in the over-20 age group, even though they are a tiny fraction
of the cases.
You've probably heard that chickenpox are itchy. It's true. The illness also may come along with a
runny nose and cough. But the good news is that chickenpox is a common illness for kids and most
people get better by just resting like you do with a cold or the flu. And the really good news is
that, thanks to the chickenpox vaccine, lots of kids don't get chickenpox at all. Kids who do get it,
if they got the shot, often get less severe cases, which means they get better quicker.
Contagiousness: How Does Chickenpox Spread?
Chickenpox is highly contagious and is spread through the air when infected people cough or
sneeze, or through physical contact with fluid from lesions on the skin. Someone who has
chickenpox is most contagious during the first 2 to 5 days that he or she is sick. That's usually about
1 to 2 days before the rash shows up. A person who has chickenpox can pass it to someone else by
coughing or sneezing. When he or she coughs, sneezes, laughs, and even talks, tiny drops come out
of the mouth and nose. These drops are full of the chickenpox virus. It's easy for someone else to
breathe in these drops or get them on his or her hands. Before you know it, the chickenpox virus
has infected someone new.
Symptoms
Chickenpox may start out seeming like a cold: You might have a runny or stuffy nose, sneezing, and
a cough. But 1 to 2 days later, the rash begins, often in bunches of spots on the chest and face.
From there it can spread out quickly over the entire body — sometimes the rash is even in a
person's ears and mouth. The number of pox is different for everyone. Some people get just a few
bumps; others are covered from head to toe.
At first, the rash looks like pinkish dots that quickly develop a small blister on top (a blister is a
bump on your skin that fills up with fluid). After about 24 to 48 hours, the fluid in the blisters gets
cloudy and the blisters begin to crust over.
Chickenpox blisters show up in waves, so after some begin to crust over, a new group of spots may
appear. New chickenpox usually stop appearing by the seventh day, though they may stop as early
as the third day. It usually takes 10–14 days for all the blisters to be scabbed over and then you are
no longer contagious.
Besides the rash, someone with chickenpox might also have a stomachache, a fever, and may just
not feel well.
Treatment
Chickenpox infection tends to be milder the
younger a child is and symptomatic treatment.
However, aspirin or products containing aspirin
must not be given to children with chickenpox (or
any fever-causing illness), as this risks causing the
serious and potentially fatal Reye's Syndrome. It
is important to maintain good hygiene and daily
cleaning of skin with warm water to avoid
secondary bacterial infection. Infection in
otherwise healthy adults tends to be more severe
and active; treatment with antiviral drugs.
6. Rabies
Background
Rabies is a serious disease that is caused by a virus. Each
year, it kills more than 50,000 people and millions of
animals around the world. Any mammal can get rabies.
Raccoons, skunks, foxes, bats, dogs, and cats can get
rabies. Cattle and humans can also get rabies. Only
mammals can get rabies. Animals that are not mammals -such as birds, snakes, and fish -- do not get rabies. Rabies
is caused by a virus. An animal gets rabies from saliva,
usually from a bite of an animal that has the disease. You
cannot get rabies from blood.
Contagiousness
People with rabies do have the virus in their saliva, beginning about a week before the symptoms
develop. Nevertheless, other animals are almost always the source of human rabies infections.
Symptoms usually begin 1 to 6 months after a bite from an infected animal. They can appear as
quickly as a week or so after the bite, or take years to develop.
Symptoms
Symptoms usually develop between 20 and 60 days after exposure. Rabid animals may become
aggressive, combative, and highly sensitive to touch and other kinds of stimulation. And they can
be vicious. This is the "furious" form of rabies, the kind traditionally associated with mad dogs.
There is also a "dumb" form of the disease in which the animal is lethargic, weak in one or more
limbs, and unable to raise its head or make sounds because its throat and neck muscles are
paralyzed. In both kinds of animal rabies, death occurs a few days after symptoms appear, usually
from respiratory failure.
In humans, the course is similar. After a symptom-free incubation period that ranges from 10 days
to a year or longer (the average is 30 to 50 days), the
patient complains of malaise, loss of appetite, fatigue,
headache, and fever. Over half of all patients have pain
(sometimes itching) or numbness at the site of exposure.
Two to 10 days later, signs of nervous system damage
appear, hyperactivity and hypersensitivity,
disorientation, hallucinations, seizures, and paralysis.
Death may be sudden, due to cardiac or respiratory
arrest.
Treatment/Prevention
Rabies can be prevented by rabies vaccine and thorough cleaning
of the wound. If you are bitten by an animal that could have
rabies, tell your parents right away so they can clean the bite
wound with soap and water and take you to see a doctor.
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Vaccinate your dogs, cats, and ferrets against rabies.
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Keep your pets under supervision.
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Do not handle wild animals. If you see a wild animal or a
stray, especially if the animal is acting strangely, call an
animal control officer.
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If you do get bitten by an animal, wash the wound with soap and water for at least 5
minutes. Make sure you tell an adult and call your doctor to see if you need shots.
Rabies kills if it is not prevented. Once signs of the disease appear in an animal or a human, they
usually die within 10 days. But you can get anti-rabies shots to fight off the disease. Rabies shots
need to be given as soon as possible after a bite has occurred, before symptoms appear. The
vaccination consists of a series of six shots given over 30 days.
One shot is given around the area of the bite. The rest are given in the arm. Sometimes an
additional shot is required the first day if they are unable to give it all around the site of the bite.
The rabies shots produce an immune response, which helps the body fight off the virus. The shot
makes the body produce antibodies that then kill the virus.
7. Cough
Background
Pertussis (or Whooping Cough), is an
infection of the respiratory system and
characterized by a “whooping” sound
when the person breathes in. In the US
it killed 5,000 to 10,000 people per
year before a vaccine was available.
Vaccination has transformed this and
between 1985-88 fewer than 100
children died from pertussis. Worldwide
in 2000, according to the WHO, around
39 million people were infected
annually and about 297,000 died.
Contagiousness
Humans are its only host. Pertussis is a severe, highly contagious
respiratory disease characterized by outbursts of coughing followed by “whooping” sound during
breathing in. Often vomiting takes place with discharge of sticky mucus. The bacteria are
transmitted directly from person to person and are most contagious in its early stage of the
disease. The symptoms of pertussis are similar to a common cold: runny nose, sneezing, mild
cough, and low-grade fever.
Symptoms
1. The first stage symptoms resemble those of a common cold, sneezing, runny nose and
coughing. During this stage, the infected person is most contagious, but is seldom diagnosed.
This stage lasts for one to two weeks.
2. The second stage is characterized by severe coughing episodes. These episodes consist of
many rapid coughs in succession, followed by a "whoop" sound and then a quick inhalation.
Often the face and lips of the infected person turn blue during these coughing fits as a result
of oxygen deprivation. Occasionally, edema, hemorrhages and vascular plugs develop in the
brain, leading to neurological damage. It is during this second stage that most diagnosis
occurs. This stage lasts for four to six weeks.
Treatment
Prevention of whooping cough is best realized by vaccination against Bordetella pertussis. The
recommended vaccination schedule is for infants to receive inoculations at 2, 4 and 6 months, and
then again at 15 months. This is to be followed by a booster at 4 to 6 years. Antibiotics are given to
children to decrease infectiousness and thereby help prevent transmission of the bacteria to
uninfected persons. In severe cases of the disease, hospitalization becomes necessary.
8. Typhoid Fever
Background
It’s not a virus, it’s a bacteria. Typhoid fever is a lifethreatening illness caused by the bacterium Salmonella
Typhi. In the United States about 400 cases occur each
year, and 75% of these are acquired while traveling
internationally. Typhoid fever is still common in the
developing world, where it affects about 21.5 million
persons each year.
Contagiousness: How is typhoid fever spread?
Salmonella Typhi lives only in humans. Persons with typhoid fever carry
the bacteria in their bloodstream and intestinal tract. In addition, a
small number of persons, called carriers, recover from typhoid fever
but continue to carry the bacteria. Both ill persons and carriers shed S.
Typhi in their feces (stool).
You can get typhoid fever if you eat food or drink beverages that have
been handled by a person who is sheddi ng S. Typhi or if sewage
contaminated with S. Typhi bacteria gets into the water you use for
drinking or washing food. Therefore, typhoid fever is more common in areas of the world where
handwashing is less frequent and water is likely to be
contaminated with sewage.
Once S. Typhi bacteria are eaten or drunk, they
multiply and spread into the bloodstream. The body
reacts with fever and other signs and symptoms.
Symptoms
Persons with typhoid fever usually have a sustained
fever as high as 103° to 104° F (39° to 40° C). They
may also feel weak, or have stomach pains,
headache, or loss of appetite. In some cases,
Typhoid fever with perforation of the bowel of a
Nigerian child. (A) Note the multiple loops of distended
gas-filled small bowel on the supine view.
patients have a rash of flat, rose-colored spots. The only way to know for sure if an illness is
typhoid fever is to have samples of stool or blood tested for the presence of S. Typhi.
Treatment
Typhoid fever can be prevented and can usually be treated with antibiotics. If you are planning to
travel outside the United States, you should know about typhoid fever and what steps you can take
to protect yourself. If you suspect you have typhoid fever, see a doctor immediately. If you are
traveling in a foreign country, you can usually call the U.S. consulate for a list of recommended
doctors.
You will probably be given an antibiotic to treat the disease. Three commonly prescribed
antibiotics are ampicillin, trimethoprim-sulfamethoxazole, and ciprofloxacin. Persons given
antibiotics usually begin to feel better within 2 to 3 days, and deaths rarely occur. However,
persons who do not get treatment may continue to have fever for weeks or months, and as many as
20% may die from complications of the infection.
Keep taking the prescribed antibiotics for as long as the doctor has asked you to take them.
Wash your hands carefully with soap and water after using the bathroom, and do not prepare or
serve food for other people. This will lower the chance that you will pass the infection on to
someone else.
Avoiding it altogether
Two basic actions can protect you from typhoid fever:
1. Avoid risky foods and drinks.
2. Get vaccinated against typhoid fever.
9. The Pox (treponema pallidum)
Background
It’s not a virus, it’s a bacteria. Syphilis is a
sexually transmitted disease (STD) caused by
the bacterium Treponema pallidum. It has
often been called “the great imitator”
because so many of the signs and symptoms
are indistinguishable from those of other
diseases. In the United States, health officials
reported over 36,000 cases of syphilis in 2006,
including 9,756 cases of primary and secondary
(P&S) syphilis.
Symptoms
- The first sign of syphilis is a lesion known as a "chancre" (a clean, painless, indurated
ulcer) which forms at the site of entry where the organism enters the body through
the mucous membranes or breaks in the epithelium. Multiple chancres occur if more
than one organism enters. The chancre lesions contain an initially local infection by
the Treponeme. Common sites for the lesions include genitalia, rectum, urethra and
mouth. The chancre, which may be accompanied by swollen glands, may last from
one to five weeks, and may disappear by itself even if no treatment is received.
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Approximately six weeks after the sore first appears, the second stage of the disease
begins. The most common symptom during this stage is a rash, which may appear on
any part of the body. Other symptoms may occur such as tiredness, fever, sore throat,
headaches, hoarseness, loss of appetite, hair loss and swollen glands. These signs and
symptoms will last two to six weeks and generally disappear in the absence of
adequate treatment.
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The third stage, called late syphilis (syphilis of over four years' duration), may involve
illness in the skin, bones, central nervous system and heart. Untreated, syphilis can
lead to destruction of soft tissue and bone, heart failure, blindness and a variety of
other conditions which may be mild to incapacitating. Women with untreated syphilis
may transmit the disease to unborn
children, which can result in death or
deformity of the child.
Treatment
Syphilis is easy to cure in its early stages. A single
intramuscular injection of penicillin, an
antibiotic, will cure a person who has had syphilis
for less than a year. Additional doses are needed to treat someone who has had syphilis for longer
than a year. For people who are allergic to penicillin,
other antibiotics are available to treat syphilis. There are
no home remedies or over-the-counter drugs that will cure
syphilis. Treatment will kill the syphilis bacterium and
prevent further damage, but it will not repair damage
already done.
Because effective treatment is available, it is important
that persons be screened for syphilis on an on-going basis
if their sexual behaviors put them at risk for STDs.
Persons who receive syphilis treatment must abstain from
sexual contact with new partners until the syphilis sores are completely healed. Persons with
syphilis must notify their sex partners so that they also can be tested and receive treatment if
necessary.
Prevention
The surest way to avoid transmission of sexually transmitted diseases, including syphilis, is to
abstain from sexual contact or to be in a long-term mutually monogamous relationship with a
partner who has been tested and is known to be uninfected.
Condoms lubricated with spermicides (especially Nonoxynol-9 or N-9) are no more effective than
other lubricated condoms in protecting against the transmission of STDs. Use of condoms
lubricated with N-9 is not recommended for STD/HIV prevention.
Transmission of a STD, including syphilis cannot be prevented by
washing the genitals, urinating, and/or douching after sex. Any
unusual discharge, sore, or rash, particularly in the groin area,
should be a signal to refrain from having sex and to see a doctor
immediately.
10. T-4 Bacteriophage
A bacteriophage is a virus which infects bacteria. In particular, the bacteriophage T4 is a virus
which infects E. Coli, a bacteria that has been used extensively for molecular biology research. The
bacteriophage T4 exemplifies the life cycle of viruses. It exists as an inactive virion until one of its
extended 'legs' comes into contact with the surface of an E. Coli. Sensors on the ends of its 'legs'
recognize binding sites on the surface of the host's cell, and this triggers the bacteriophage into
action. The bacteriophage binds to the surface of the host, punctures the cell with its injection
tube, and then injects its own genetic blueprint. This genetic information subverts the host cell's
normal operation and sets the cell's biosynthetic machinery to work creating replicas of the virus.
These newly created viruses escape from the cell and then float about dormant until one happens
to come into contact with a new host cell.
Secured to its victim by the stringy fibers visible here, the tail acts like a needle in
piercing the bacterium’s cellular wall. The head then passes its reservoir of DNA
down the tail and into the host. Within 25 minutes the dying cell is teeming with
about 100 fresh copies of the virus, which are created by the rearrangment of the
bacterium’s own genetic contents.
Life Cycle