Reference Documents


Signs and Symptoms of Infectious Diseases

Infectious diseases are caused by micro-organisms, such as bacteria, viruses, parasites or fungi. These diseases can spread from the environment or from one person to another resulting in illness.

Signs and symptoms vary depending on the organism causing the infection. Infections can be classified in a number of different ways. They may be localized (affecting a specific part of the body) or systemic (affecting the body as a whole). Some are generalized and non-specific, like fever and fatigue while others are specific to the body part, such as a rash or swelling of a joint.

The body’s first line of response to any infection may be characterized by some generalized signs and symptoms as follows:

  • Fever
  • Chills
  • Headache
  • Fatigue
  • Malaise
  • Muscle aches
  • Joint aches
  • Swollen lymph nodes

Examples of Infectious Diseases include:

Enteric Diseases and Food-Borne Diseases: These diseases are caused by micro-organisms such as viruses, bacteria and parasites that cause intestinal illness. They most frequently result from consuming contaminated food or water and some can spread from person to person.

Symptoms of a gastrointestinal tract infection may include:

  • Abdominal pain
  • Diarrhea
  • Nausea and vomiting
  • Fever

Respiratory Disease: These diseases are caused by organisms such as viruses or bacteria that affect the respiratory system (e.g., lungs and throat). The organisms can be spread by coughing, sneezing or face-to-face contact.

Symptoms may include:

  • Sneezing
  • Runny nose
  • Nasal congestion/discharge
  • Scratchy or sore throat
  • Coughing
  • Shortness of breath
  • Fever

Eye infections: These infections are common because the eye is vulnerable to pathogens that are easily transmitted by hand-to-eye contact or an eye injury. An eye infection often involves only one eye but can easily spread to both.

Symptoms may include:

  • Deep pink color in the white of the eye
  • Eye swelling, itchiness, or burning
  • Excessive tearing
  • Eye discharge

Blood Borne Infections (BBI): These viruses are carried in the blood, and can be transmitted through sexual contact, sharing needles, needle-stick injuries, from mother to baby during pregnancy, during birth or through breast feeding. BBIs may also exist in other body fluids. Some examples of BBIs include Hepatitis B and C. 

Sexually Transmitted Infections (STIs): STIs are caused by micro-organisms such as viruses or bacteria that are transmitted through sexual contact.

Vaccine Preventable Diseases (VPD): Some diseases are caused by viruses and bacteria, and can be prevented by vaccines

Some examples of VPDs include:

  • Chicken Pox / Shingles
  • Measles
  • Hepatitis A/B
  • Influenza
  • Tetanus

Vector-Borne and Zoonotic Diseases: Vector-borne and zoonotic diseases are caused by viruses, bacteria or parasites that are transmitted to humans from animals or insects.