Diseases
In this section, we will show how diseases and microorganisms are directly related.
Protozoa
Among the 30 000 species of protozoa which exist, the Trypanosome kind is one of most known because of the disease it causes. It is transmitted by the Tsé-Tsé fly which contaminates itself by aspiring the blood of a sick man. The disease of the sleep is exclusively African. The infected man has an intermittent fever, oedemas, a hypertrophy of lymphatic ganglia, nervous disorders (agitation or somnolence). Death is the usual end of the disease. If it is not treated, the disease lasts several years. This scary disease was stopped thanks to chemotherapy and nowadays, it is not a social plague anymore.
Fungi
In a sick immune system, germs such as Candida fungi (responsible for mycose) usually harmless may develop themselves and be responsible for diseases : Lily of the valley, the genital mucous membranes (vulvo-vaginits), the folds (intertrigo) on the level of the groin or between the toes. The dermatophytes are responsible for intertrigo and several varieties of tineas (patches with loss of hair). Some can be located in the lung as well: aspergillosis, cryptococcosis, histoplasmosis. There are many medicine like antifongic, different from antibiotics, used especially locally, against the cutaneous mycoses.
Bacteria
There are about 200 bacteria species which are pathogenic for human beings, for example the tetanus, the leprosy,the cholera, the plague and the syphilis which are responsible for the most dealdly diseases this past century. The level of bacteria infection depends on the bacteria colony and on the health on the host (here, we consider the human body).
The ways to fight against bacteria infection are well known: antibiotics synthetized by other microorganisms (penicillium is produced by penicillin, main component of aspirin). Anyway, those medicines are way to much used and bacteria change to fight against them.
Viruses
The influenza is one of the diseases which medicine still cannot cure perfectly. The only medicine commonly known is to go to bed. Indeed this disease has been known for a very long time and still does not have a 100% effective medicine. This disease is caused by the flu virus which appears under different forms.
The flu virus causes fevers and loose coughs. Influenza, or pandemias Epidemics have already killed many people: in 1918, a worldwide epidemic killed more than 20 million people! The 1968 (influenza of Hongkong) and 1977(Russian influenza) epidemics were as deadly. Currently, the influenza kills 4 000 people per years in a country like France, and 20 000 during epidemics, affecting the sensitive people (especially old or feverish people).
There are various way of fighting against the virus : the usual medicine which causes a drop in the fever or vaccines. Medicine research has improved significantly since the discovery of the virus in 1933: we know several colonies of flu virus, that does not facilitate the work of the researchers! Moreover, every year, the virus changes form: this is why people need to be vaccinate every year against the well-known flu virus.
A new medicine type developed by researchers will be launched on the market soon : Zanamivir and the GS 4104 (active molecules of the medicine) interact on the active site of an enzyme and prevent viral particles to move from one cell to another and to infect new cells.
The mad cow and Creutzfeldt-Jakob diseases which affect humans are spongiform encephalopathy. Infected cows lose their balance. Infected human beings show balanced problems first and then madness. The brain of the people affected by this disease has typical lesions: it is full of small holes and looks like a sponge (the name of the disease derives from this term).