Yellow fever

What is Yellow fever
Yellow fever is a hemorrhagic fever caused by a virus spread by a particular species of mosquito. It is most common in areas of Africa and South America, affecting travelers to and residents of those areas.
In mild cases, yellow fever causes fever, headache, nausea and vomiting. But yellow fever can become more serious, causing bleeding (hemorrhaging), heart, liver and kidney problems. Up to 50 percent of those with the more severe form of yellow fever die of the disease.
There is no specific treatment for yellow fever. But getting a yellow fever vaccine before traveling to an area in which the virus is known to exist can protect you from the disease.

Symptoms
During the first three to six days after you've contracted yellow fever — the incubation period — you won't experience any signs or symptoms. After this, the virus enters an acute phase and then, in some cases, a toxic phase that can be life-threatening.
Acute phase Once the yellow fever virus enters the acute phase, you may experience signs and symptoms including:
Fever
Headache
Muscle aches, particularly in your back and knees
Nausea, vomiting or both
Loss of appetite
Dizziness
Red eyes, face or tongue
These signs and symptoms usually improve and are gone within three to four days.

Toxic phase

Although signs and symptoms may disappear for a day or two following the acute phase, 15 percent of those with acute yellow fever then enter a toxic phase. During the toxic phase, acute signs and symptoms return and more severe and life-threatening ones also appear. These can include:
Yellowing of your skin and the whites of your eyes (jaundice)
Abdominal pain and vomiting, sometimes blood
Decreased urination
Bleeding from the nose, mouth and eyes
Heart dysfunction (arrhythmias)
Liver and kidney failure
Brain dysfunction including delirium, seizures and coma
About 20 percent to 50 percent of those who enter the toxic phase die of the disease. The rest usually recover without significant problems.

Sleep Apnea

What is sleep Apnea

Sleep apnea is a sleep disorder in which your breathing stops or gets shallow temporarily. These pauses in your breathing can occur dozens of times each hour while you sleep.

Causes, incidence, and risk factors

More than 100 different diorder of sleeping and waking have been identified. They can be grouped in four main categories:
Problems with falling and staying asleep
Problems with staying awake
Problems with adhering to a regular sleep schedule

Sleep-disruptive behaviors

PROBLEMS WITH FALLING AND STAYING ASLEEP

Insomenia includes any combination of difficulty with falling asleep, staying asleep, intermittent
Wakefulness and early-morning awakening. Episodes may be transient (come and go), short-term (lasting as long as 2 to 3 weeks), or chronic (long-lasting).
Common factors associated with insomnia include:
Physical illness
Depression
stress
Poor sleeping environment such as excessive noise or light
Caffeine
Alcohol or other drugs
Use of certain medications
Heavy smoking
Physical discomfort
Daytime napping
Counterproductive sleep habits:

Early bedtimes
Excessive time spent awake in bed

Disorders include:

Psychophysiological insomnia (learned insomnia)
Delayed sleep phase syndrome -- where a patient's internal clock is constantly out of synch with the "accepted" day / night phases; for example, patients feel best if they can sleep from 4AM to noon
Hypnotic-dependent sleep disorder -- insomnia resulting from building tolerance to, or stopping, certain types of sleep medications
Stimulant-dependent sleep disorder -- insomnia resulting depending on, or stopping, certain types of stimulants

PROBLEMS WITH STAYING AWAKE

Disorders of ExcessiveSleepiness are called hypersomnias. These include:
Sleep apnea
Narcolepsy
Restless leg syndrome
Periodic limb movement disorder
Obstructive sleep apnea
Central sleep apnea
Ideopathic hypersomnia

Respiratory muscle weakness associated sleep disorder
Sleep apnea more commonly affects obese people, but it may affect anyone with a short neck or a small jaw, regardless of weight. The disorder causes breathing to stop intermittently during sleep, resulting in the person being awakened repeatedly. People with sleep apnea often have difficulty achieving prolonged deep sleep. This results in excessive daytime sleepiness.