Disease Causative Agents

Hemophilia is an X-linked recessive genetic disorder caused by deficiency in clotting factors (Factor VIII or IX), passed from parents to offspring. Typhoid is an infectious bacterial disease, while blood cancers and bone cancers are typically acquired (not inherited) conditions.

A white coating on the tongue is typically caused by a bacterial biofilm - colonies of bacteria growing on the tongue's surface. This is normal oral flora accumulation, not fungi, algae, or viruses. Good oral hygiene including tongue cleaning can remove this biofilm.

WHO officially named the 2009 pandemic virus 'Influenza A (H1N1)' - not 'H1N1 flu' or just 'North American influenza'. The parenthetical (H1N1) specifies the subtype. 'Influenza A virus subtype H1N1' is overly verbose and not the official designation format.

SARS stands for Severe Acute Respiratory Syndrome, a viral respiratory illness caused by the SARS-associated coronavirus. The outbreak emerged in 2002-2003. The options South African Respiratory Service (A), Severe acquired (B - missing 'acute'), and South Asian Revenue Service (D) are incorrect.

Common cold (caused by rhinoviruses) is the most contagious disease because it spreads through airborne droplets, direct contact, and contaminated surfaces with high efficiency. While diseases like measles are more severe in contagiousness, cold is the most frequently transmitted.

Tooth decay (dental caries) affects nearly 3.5 billion people globally, making it the most widespread non-contagious disease. AIDS is infectious/contagious, while fever is merely a symptom rather than a specific disease. Cancer, though non-contagious, has significantly lower prevalence compared to tooth decay.

Bacillus anthracis is the correct causative agent of anthrax, a gram-positive bacterial infection. Junin virus causes Argentine hemorrhagic fever, not anthrax. Yersinia is a different bacterial genus, and Plasmodium causes malaria.

Dengue fever is caused by flaviviruses, specifically Dengue virus (DENV), transmitted by Aedes mosquitoes. Bacillus cereus is a bacterium causing food poisoning. BK virus causes respiratory infections. Machupo virus causes Bolivian hemorrhagic fever.

Clostridium perfringens is a common bacterial cause of food poisoning, typically associated with improperly cooked meats and gravies that have been left at unsafe temperatures. While multiple bacteria can cause food poisoning, C. perfringens is one of the most frequently identified pathogens in foodborne outbreaks.

Yersinia pestis is the bacterium that causes plague, including bubonic, septicemic, and pneumonic forms. It is transmitted primarily by fleas from rodents. The other options are incorrect: Varicella zoster causes chickenpox, Anaplasma causes anaplasmosis, and Balantidium coli causes balantidiasis.

Bird flu, or avian influenza, is medically known as H5N1. This is a subtype of influenza A virus that primarily affects birds but can also infect humans. H1N1 is swine flu, H2O is water, and H2SO4 is sulfuric acid.

An ulcer is an open sore or break in the skin or mucous membrane that fails to heal. Common types include peptic ulcers (stomach/duodenum) and pressure ulcers (bedsores).

Tooth decay (dental caries) is indeed one of the most common chronic diseases worldwide, affecting people of all ages. The other options are all contagious/communicable diseases: AIDS is caused by HIV transmission, Swine Flu (H1N1) is a viral influenza, and the common cold is viral. Non-contagious diseases cannot spread from person to person.

Swine flu (H1N1 influenza) is primarily transmitted through respiratory droplets when an infected person coughs, sneezes, or talks, rather than being truly airborne like tuberculosis or measles. While droplets can travel through air for short distances, the virus is not classified as airborne in the strict sense - it requires close contact for transmission. Airborne transmission refers to pathogens that can remain suspended in air for longer periods and travel longer distances.

Tooth decay (dental caries) is the most common non-contagious disease worldwide, affecting about 2.3 billion people globally. Swine flu, SARS, and headaches are either contagious or not classified as the most common diseases in epidemiological studies.