Communicable diseases are infections caused by bacteria, viruses, fungi and parasites. They are usually passed from person to person through contact with bodily fluids, food, surfaces, animals, insects or blood products. Some diseases can be mild, while others can be very dangerous. While some are not contagious, some people can still transmit the disease to others. These can include HIV, hepatitis, and sexually transmitted diseases.

Communicable diseases can be categorized into two major groups: pathogenic and non-pathogenic. Pathogenic refers to the disease-causing agent, while non-pathogenic is the lack of disease in the host. Both types of disease can be fatal or can only cause a mild infection. A few of the most common forms of communicable disease are influenza, hepatitis, swine flu, measles, mumps, pertussis, and chickenpox.

Diseases can be transmitted through the mouth, nose, throat, or eye. People can also get infections through contaminated water, foods, or through the bite of an insect. For example, a person can be infected with hepatitis by eating undercooked hamburgers or drinking unpasteurized fruit juice. The most common carriers of disease are mosquitoes. Other sources of infection can come from animal feces or handling the waste of animals.

Bacteria are one of the most common forms of pathogens. Viruses, protozoa, and fungi are also a few of the most common kinds of pathogens. All of these are characterized by a lack of a complicated cell structure, making them easy to pass from person to person. In some cases, viruses can cause severe infections, while in other cases, they may not show symptoms.

Some illnesses can be attributed to a lack of nutrition, obesity, or genetics. Others can be a result of the immune system’s reaction to the pathogens. Many infectious diseases require treatment to cure. However, some of them can disappear on their own without treatment.

Among the most common kinds of communicable diseases are the cold and flu. People can pick up the germs from their nose, mouth, or doorknob, and can be infected through contaminated foods, surfaces, and air. It is important to remember to wash hands after using the toilet, and not to touch your mouth, eyes or nose when you are sneezing. If you think you have been exposed to a contagious disease, report it to your doctor or local health department.

Lyme disease, one of the most dangerous communicable diseases, is a potentially fatal infection that is spread through the bite of an infected tick. In some cases, the disease can cause joint pain, neurological disorders, and even heart problems. Borrelia burgdorferi is the most common organism responsible for the disease, but other infections may be caused by other viruses.

Malaria is a tropical disease caused by a protozoan genus called Plasmodium. This infection can be highly contagious, but is typically treated with a vaccine. Because this disease is so dangerous, it is imperative to know how to prevent it.

Vaccinations are a highly effective form of protection against malaria. Malaria can be deadly if not properly treated, so vaccination programs are extremely important.