Jaundice, or icterus, is the yellow discoloration of the skin, sclerae, and mucous membranes. It happens when plasma bilirubin levels rise above 2.5-3 mg/dL, leading to bilirubin deposition in tissue.Bilirubin is a byproduct of hemoglobin degradation. In macrophages, hemoglobin breaks down into globin and heme. Globin is converted into amino acids, while heme is turned into biliverdin by heme oxygenase, which is then reduced to unconjugated bilirubin by biliverdin reductase.Unconjugated...

Yellow fever is a viral hemorrhagic disease caused by the yellow fever virus (YFV), a member of the Flaviviridae family. It is transmitted primarily by Aedes and Haemagogus mosquitoes in tropical and subtropical regions of Africa and South America. After transmission through a mosquito bite, the virus initially replicates in skin-resident immune cells such as dendritic cells and macrophages. These cells then migrate to the lymph nodes, where viral replication increases, eventually leading to...

Viral hepatitis is an inflammatory condition of the liver caused by infection with hepatotropic viruses, most commonly hepatitis A, B, C, D, and E. Despite variations in structure and transmission, all viruses mentioned infect hepatocytes and provoke immune responses that can hinder liver function. Additionally, some non-hepatotropic viruses can also lead to hepatic inflammation.Hepatitis A VirusHepatitis A virus (HAV) is transmitted through the fecal–oral route, typically by ingestion of food...

Liver and gallbladder diseases are a significant health concern, with prominent conditions including cirrhosis, hepatitis, non-alcoholic fatty liver disease (NAFLD), and gallstones. Jaundice is a common manifestation of liver and biliary disease.
Cirrhosis is characterized by the scarring of hepatic lobules in the liver, which are replaced by fibrous tissue, affecting the liver's normal functioning. NAFLD, on the other hand, is caused by an excessive build-up of fat in the liver, not related to...

Cytomegalovirus (CMV) disease is caused by human cytomegalovirus, a double-stranded DNA virus of the Herpesviridae family. While primary CMV infection is often asymptomatic in immunocompetent individuals, the virus can cause severe disease in neonates and immunocompromised patients. CMV is the most common cause of congenital viral infection in the United States, and a major pathogen in solid organ and hematopoietic stem cell transplant recipients.CMV is transmitted via bodily fluids, sexual...

Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...