Infection causing inflammation of lung air sacs (alveoli). Can be bacterial, viral, or fungal. Leading cause of death in children worldwide and serious illness in elderly.

A mosquito-borne flavivirus most commonly transmitted by Culex species mosquitoes. Can cause neurological disease in humans. Birds are primary hosts. First identified in Uganda in 1937; emerged in North America in 1999.

Cancer arising from the nasopharynx, the area behind the nose and above the back of the throat. Strongly associated with Epstein-Barr virus (EBV), genetic factors, and certain dietary habits (salted fish). Common in Southeast Asia and North Africa.

Also known as delta hepatitis, caused by the hepatitis D virus (HDV) which requires hepatitis B virus to replicate. The most severe form of viral hepatitis with rapid progression to cirrhosis. Occurs as coinfection (with HBV) or superinfection (in chronic HBV).

Inability to fully digest lactose, the sugar in milk and dairy products, due to deficiency of lactase enzyme in the small intestine. Very common worldwide, especially in certain ethnic groups. Not dangerous but can cause uncomfortable symptoms.

A parasitic disease caused by Leishmania protozoa, transmitted by sandfly bites. Three main forms: cutaneous (skin sores), mucocutaneous (destruction of mucous membranes), and visceral (affects organs, fatal if untreated). Affects 1-2 million people annually, with 350 million at risk in 98 countries.

A viral respiratory illness caused by Middle East Respiratory Syndrome Coronavirus (MERS-CoV). First reported in Saudi Arabia in 2012. Transmitted from camels to humans and person-to-person in close contact. Case fatality rate approximately 35%. Most cases in Arabian Peninsula.