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Common Infectious Diseases Worldwide
Sources: The Centers for Disease Control (CDC);
The World Health Organization (WHO).
The following is a list of the most common infectious diseases
throughout the world today. Accurate caseload numbers are difficult to
determine, especially because so many of these diseases are endemic to
developing countries, where many people do not have access to modern
medical care. Approximately half of all deaths caused by infectious
diseases each year can be attributed to just three diseases: tuberculosis,
malaria, and AIDS. Together, these diseases cause over 300 million
illnesses and more than 5 million deaths each year.
The list does not include diseases that have received a significant
amount of media attention in recent years—such as Ebola Hemorrhagic Fever
or West Nile Virus >
but which in fact have infected a relatively small number of people
African Trypanosomiasis (“sleeping sickness”): African
trypanosomiasis is spread by the tsetse fly, which is common to many
African countries. The World Health Organization (WHO) estimates that
nearly 450,000 cases occur each year. Symptoms of the disease include
fever, headaches, joint pains, and itching in the early stage, and
confusion, sensory disturbances, poor coordination, and disrupted sleep
cycles in the second stage. If the disease goes untreated in its first
stage, it causes irreparable neurological damage; if it goes untreated in
its second stage, it is fatal.
Cholera: Cholera is a disease spread mostly through contaminated
drinking water and unsanitary conditions. It is endemic in the Indian
subcontinent, Russia, and sub-Saharan Africa. It is an acute infection of
the intestines with the bacterium Vibrio cholerae. Its main symptom
is copious diarrhea. Between 5% and 10% of those infected with the disease
will develop severe symptoms, which also include vomiting and leg cramps.
In its severe form, cholera can cause death by dehydration. An estimated
200,000 cases are reported to WHO annually.
Cryptosporidiosis: Cryptosporidiosis has become one of the most
common causes of waterborne disease in the United States in recent years;
it is also found throughout the rest of the world. It is caused by a
parasite that spreads when a water source is contaminated, usually with
the feces of infected animals or humans. Symptoms include diarrhea,
stomach cramps, an upset stomach, and slight fever. Some people do not
exhibit any symptoms.
Dengue: WHO estimates that 50 million cases of dengue fever
appear each year. It is spread through the bite of the Aedes
aegypti mosquito. Recent years have seen dengue outbreaks all over
Asia and Africa. Dengue fever can be mild to moderate, and occasionally
severe, though it is rarely fatal. Mild cases, which usually affect
infants and young children, involve a nonspecific febrile illness, while
moderate cases, seen in older children and adults, display high fever,
severe headaches, muscle and joint pains, and rash. Severe cases develop
into dengue hemorrhagic fever, which involves high fever, hemorrhaging,
and sometimes circulatory failure.
Hepatitis A: Hepatitis A is a highly contagious liver disease
caused by the hepatitis A virus. Spread primarily by the fecal-oral route
or by ingestion of contaminated water or food, the number of annual
infections worldwide is estimated at 1.4 million. Symptoms include fever,
fatigue, jaundice, and dark urine. Although those exposed usually develop
lifelong immunity, the best protection against Hepatitis A is
vaccination.
Hepatitis B: Approximately 2 billion people are infected with
the hepatitis B virus (HBV), making it the most common infectious disease
in the world today. Over 350 million of those infected never rid
themselves of the infection. Hepatitis is an inflammation of the liver
that causes symptoms such as jaundice, extreme fatigue, nausea, vomiting,
and stomach pain; hepatitis B is the most serious form of the disease.
Chronic infections can cause cirrhosis of the liver or liver cancer in
later years.
Hepatitis C: Hepatitis C is a less common, and less severe, form
of hepatitis. An estimated 180 million people worldwide are infected with
hepatitis C virus (HCV); 3–4 million more are infected every year. The
majority of HCV cases are asymptomatic, even in people who develop chronic
infection.
HIV/AIDS: See Understanding AIDS.
Influenza: Several influenza epidemics in the 20th century
caused millions of deaths worldwide, including the worst epidemic in
American history, the Spanish influenza outbreak that killed more than
500,000 in 1918. Today influenza is less of a public health threat, though
it continues to be a serious disease that affects many people.
Approximately 20,000 people die of the flu in the United States every
year. The influenza virus attacks the human respiratory tract, causing
symptoms such as fever, headaches, fatigue, coughing, sore throat, nasal
congestion, and body aches.
Japanese Encephalitis: Japanese encephalitis is a mosquito-borne
disease endemic in Asia. Around 50,000 cases occur each year; 25% to 30%
of all cases are fatal.
Leishmaniasis: Leishmaniasis is a disease spread by the bite of
the sandfly. It is found mostly in tropical countries. There are several
types of leishmaniasis, and they vary in symptoms and severity. Visceral
leishmaniasis (VL, or kala azar) is the most severe; left
untreated, it is always fatal. Its symptoms include fever, weight loss,
anemia, and a swelling of the spleen and liver. Mucocutaneous
leishmaniasis (MCL, or espundia) produces lesions that affect the
nose, mouth, and throat and can destroy their mucous membranes. Cutaneous
leishmaniasis (CL) produces skin ulcers, sometimes as many as 200, that
cause disability and extensive scarring. Diffuse cutaneous leishmaniasis
(DCL) is similar to CL, and infected people are prone to relapses.
Approximately 12 million cases of leishmaniasis exist today.
Malaria: Malaria is a mosquito-borne disease that affects more
than 500 million people annually, causing between 1 and 3 million deaths.
It is most common in tropical and subtropical climates and is found in 90
countries—but 90% of all cases are found in Sub-Saharan Africa. Most of
its victims are children. The first stage consists of shaking and chills,
the next stage involves high fever and severe headache, and in the final
stage the infected person's temperature drops and he or she sweats
profusely. Infected people also often suffer from anemia, weakness, and a
swelling of the spleen. Malaria was almost eradicated 30 years ago; now it
is on the rise again.
Measles: Measles is a disease that has seen a drastic reduction
in countries where a vaccine is readily available, but it is still
prevalent in developing countries, where most of the 242,000 deaths (out
of 30 million cases) it caused in 2006 occurred. Symptoms include high
fever, coughing, and a maculo-papular rash; common complications include
diarrhea, pneumonia, and ear infections.
Meningitis: Meningitis, often known as spinal meningitis, is an
infection of the spinal cord. It is usually the result of a viral or
bacterial infection. Bacterial meningitis is more severe than viral
meningitis and may cause brain damage, hearing loss, and learning
disabilities. An estimated 1.2 million cases of bacterial meningitis occur
every year, over a tenth of which are fatal. Symptoms include severe
headache, fever, nausea, vomiting, lethargy, delirium, photophobia, and a
stiff neck.
Onchocerciasis (“river blindness”): Onchocerciasis is caused by
the larvae of Onchocerca volvulus, a parasitic worm that lives in
the human body for years. It is endemic in Africa, where nearly all of the
18 million people infected with the disease live. Of those infected, over
6.5 million have developed dermatitis and 270,000 have gone blind.
Symptoms include visual impairment, rashes, lesions, intense itching, skin
depigmentation, and lymphadenitis.
Pneumonia: Pneumonia has many possible causes, but it is usually
an infection of the streptococcus or mycoplasma bacteria. These bacteria
can live in the human body without causing infection for years, and only
surface when another illness has lowered the person's immunity to disease.
Streptococcus pneumoniae causes streptococcal pneumonia, the most
common kind, which is more severe than mycoplasmal pneumonia. S.
pneumoniae is responsible for more than 100,000 hospitalizations for
pneumonia annually, as well as 6 million cases of otitis media and over
60,000 cases of invasive diseases such as meningitis.
Rotavirus: Rotavirus is the most common cause of viral
gastroenteritis worldwide. It kills more than 600,000 children each year,
mostly in developing countries. Symptoms include vomiting, watery
diarrhea, fever, and abdominal pain.
Schistosomiasis: Schistosomiasis is a parasitic disease that is
endemic in many developing countries. Roughly 200 million people worldwide
are infected with the flukeworm, whose eggs cause the symptoms of the
disease. Some 120 million of those infected are symptomatic, and 20
million suffer severely from the infection. Symptoms include rash and
itchiness soon after becoming infected, followed by fever, chills,
coughing, and muscle aches.
Shigellosis: Shigella infection causes an estimated 600,000
deaths worldwide every year. It is most common in developing countries
with poor sanitation. Shigella bacteria cause bacillary dysentery, or
shigellosis. Symptoms include diarrhea with bloody stool, vomiting, and
abdominal cramps.
Strep Throat: Strep throat is caused by the streptococcus
bacteria. Several million cases of strep throat occur every year. Symptoms
include a sore throat, fever, headache, fatigue, and nausea.
Tuberculosis: Tuberculosis causes nearly 2 million deaths every
year, and WHO estimates that nearly 1 billion people will be infected
between 2000 and 2020 if more effective preventive procedures are not
adopted. The TB bacteria are most often found in the lungs, where they can
cause chest pain and a bad cough that brings up bloody phlegm. Other
symptoms include fatigue, weight loss, appetite loss, chills, fever, and
night sweats.
Typhoid: Typhoid fever causes an estimated 600,000 deaths
annually, out of 12–17 million cases. It is usually spread through
infected food or water. Symptoms include a sudden and sustained fever,
severe headache, nausea, severe appetite loss, constipation, and sometimes
diarrhea.
Yellow Fever: Yellow fever causes an estimated 30,000 deaths
each year, out of 200,000 cases. The disease has two phases. In the “acute
phase,” symptoms include fever, muscle pain, headache, shivers, appetite
loss, nausea, and vomiting. This lasts for 3–4 days, after which most
patients recover. But 15% will enter the “toxic phase,” in which fever
reappears, along with other symptoms, including jaundice; abdominal pain;
vomiting; bleeding from the mouth, nose, eyes, and stomach; and
deterioration of kidney function (sometimes complete kidney failure). Half
of all patients in the toxic phase die within two weeks; the other half
recover.
See also Malaria, HIV/AIDS, Tuberculosis,
Sexually
Transmitted Diseases, Tropical
Diseases, Rare
and Deadly Diseases, Food-Borne
Diseases, Mosquito
and Tick-Borne Diseases, Childhood
Diseases.
Information Please® Database, © 2007 Pearson Education,
Inc. All rights reserved.
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