In these cases, the infection lasts only three to six days.But in 15% of cases, people enter a second, toxic phase of the disease characterized by recurring fever, this time accompanied by jaundice due to liver damage, as well as abdominal pain. Bleeding in the mouth, nose, the eyes, and the gastrointestinal tract cause vomit containing blood, hence the Spanish name for yellow fever, vómito negro ("black vomit"). There may also be kidney failure, hiccups, and delirium.Among those who develop jaundice, the fatality rate is 20 to 50%, while the overall fatality rate is about 3 to 7.5%. Severe cases may have a mortality greater than 50%.Surviving the infection provides lifelong immunity, and normally results in no permanent organ damage. Complication
Yellow fever can lead to death for 20% to 50% of those who develop severe disease. Jaundice, fatigue, heart rhythm problems, seizures and internal bleeding may also appear as complications of yellow fever during recovery time. Cause
Yellow fever is caused by yellow fever virus, an enveloped RNA virus 40–50 nm in width, the type species and namesake of the family Flaviviridae. It was the first illness shown to be transmissible by filtered human serum and transmitted by mosquitoes, by American doctor Walter Reed around 1900.
Immunodeficiency, also known as immunocompromisation, is a state in which the immune systems ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that affect the patients immune system. Examples of these extrinsic factors include HIV infection and environmental factors, such as nutrition. Immunocompromisation may also be due to genetic diseases/flaws such as SCID. In clinical settings, immunosuppression by some drugs, such as steroids, can either be an adverse effect or the intended purpose of the treatment. Examples of such use is in organ transplant surgery as an anti-rejection measure and in patients with an overactive immune system, as in autoimmune diseases. Some people are born with intrinsic defects in their immune system, or primary immunodeficiency.A person who has an immunodeficiency of any kind is said to be immunocompromised. An immunocompromised individual may particularly be vulnerable to opportunistic infections, in addition to normal infections that could affect anyone. It also decreases cancer immunosurveillance, in which the immune system scans the bodys cells and kills neoplastic ones. They are also more susceptible to infectious diseases owing to reduced protection afforded by vaccines. Types
By affected component
Humoral immune deficiency (including B cell deficiency or dysfunction), with signs or symptoms depending on the cause, but generally include signs of hypogammaglobulinemia (decrease of one or more types of antibodies) with presentations including repeated mild respiratory infections, and/or agammaglobulinemia (lack of all or most antibody production) which results in frequent severe infections and is often fatal.