communicable diseases

What is a communicable disease?

An infectious disease that can be passed from person to person and are caused by pathogens, a pathogen is a microorganism that causes disease. There are four types of pathogens:

Bacterial Fungal Viral Protist

Pathogens can cause disease in one of two ways:

1) damaging cells - invade cell and cause it to produce proteins to replicate itself until cell ruptures

2) producing toxins - these toxins will affect your body + make you feel ill

Both bacteria and viruses reproduce rapidly inside the body. Bacteria multiply by process of simple cell division called binary fission. In this process, one bacterium divides into two. This can happen as often as once every 20 minutes if they have enough nutrients and a suitable temperature. Viruses live and reproduce inside cells, causing cell damage.

VIRAL DISEASES

Measles

Measles is a viral disease showing symptoms of fever and red skin rash. Measles is a serious illness that can be fatal if complications arise. For this reason most young children are vaccinated against measles. The measles virus is spread by inhalation of droplets from sneezes and coughs.

HIV

HIV initially causes a flu like illness. Unless successfully controlled with antiretroviral drugs the virus attacks the body’s immune cells. Late stage HIV infection, or AIDS, occurs when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers. HIV is spread by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles.

Tobacco Mosaic Virus

TMV is a widespread plant pathogen affecting many species of plants including tomatoes. It gives a distinctive ‘mosaic’ pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis.

BACTERIAL DISEASES

Salmonella

Salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions. In the UK, poultry are vaccinated against Salmonella to control the spread. Fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete.

Gonorrhoea

Gonorrhoea is a sexually transmitted disease with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating. It is caused by a bacterium and was easily treated with the antibiotic penicillin until many resistant strains appeared. Gonorrhoea is spread by sexual contact. The spreads can be controlled by treatment with antibiotics or the use of a barrier method of contraceptions such as a condom.

FUNGAL DISEASES

Rose black spot

RBS is a fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early. It affects the growth of the plant as photosynthesis is reduced. It is spread in the environment by water or wind. RBS can be treated by using fungicides and/or removing and destroying the affected.

PROTIST DISEASES

Malaria

The malarial protist has a life cycle that includes the mosquito. Malaria causes recurrent episodes of fever and can be fatal. The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten.