The correct answer is ​Only 4. Plague is an infectious disease caused by Yersinia pestis bacteria, found in small mammals and their fleas. Humans can be contaminated by the bite of infected fleas, through direct contact with infected materials, or by inhalation. Tetanus is a bacterial disease. It is also known as "lockjaw" as it causes stiffness in the jaw muscles. Causative Agent Bacteria Clostridium tetani Mode of Acquiring The infection is contracted when a deep flesh wound is exposed to soil, dust, or animal feces that is contaminated with the bacteria. Affects The nervous system leads to muscle stiffness and spasms. Symptoms Stiffness in jaw, neck, and abdominal muscles Difficulty in swallowing Painful spasms whooping cough is also known as Pertussis. It is a highly contagious bacterial disease. Causative Agent Bordetella pertussis Mode of Acquiring Sharing breathing space with an infected person who is coughing or sneezing. Affects Upper respiratory system. Symptoms Mild Stage Mild cough Sneezing and runny nose Fever Severe Stage Rapid coughs end with a high pitched "whoop" sound Vomiting and weakness The dreaded human disease, syphilis, is caused by a bacterium. The cause of syphilis is a bacterium called Treponema pallidum. It usually spreads by sexual contact that starts as a painless sore. Key Points Symptoms include fever, weakness, and headache. Tetanus is commonly known as "lockjaw” is a serious bacterial infection caused by Clostridium tetani bacteria. The disease affects the nervous system and the brain. Whooping cough, also called pertussis, is a serious respiratory infection caused by a type of bacteria called Bordetella pertussis. The infection causes violent, uncontrollable coughing that can make breathing difficult. Syphilis is a bacterial infection usually spread by sexual contact. It is caused by the bacterium Treponema pallidum.