Star Trek Diseases

Anchilles fever: A deadly disease capable of spreading rapidly and causing widespread and painful deaths
Andronesian Encephalitis: A disease transmitted by airborne particles
Aphasia:  is a dysfunction of certain brain centers affecting the ability to communicate in a coherent manner. Different forms of aphasia exist.
Aphasia virus: A Bajoran-created virus that disrupts the brain's ability to process audio and visual stimuli
Ba'ltmasor Syndrome: A disease that afflicts Klingons, which requires regular treatments given by injection
Barclay's Protomorphosis Syndrome: An airborne disease created by a synthetic T-cell that mutated and caused victims to "deevolve" into primitive versions of their respective species. Also known as the intron virus 
Bendii Syndrome: A rare disease that affects elderly Vulcans, causing gradual loss of emotional control 
Blight: A genetic plague created by the Jem'Hadar to punish certain populations
Cholera: Acute infectious enteritis, common on Earth in the 19th and 20th centuries
Darnay's disease: A deadly ailment that attacks the brain and nervous system of its victims
Dorek Syndrome: A very rare Ferengi disease
Enantiodromia Psychological term that literally means conversion into the opposite
Eosinophilia: An abnormally high count of serum eosinophils, a type of humanoid white blood cell
Forrester Trent Syndrome: A very rare degenerative neural disease that when untreated causes paralysis and even death
Hesperan Thumping Cough: A flu-like affliction

 

Holodiction: Not a real disease, but rather a psychological condition where someone becomes so caught up in the holographic simulations that the real world becomes unimportant
Hyperacceleration: A biochemical condition that causes the victim to experience one second as if it were an hour
Iresine Syndrome:  is a very rare neurological disorder in humanoids characterized by a peculiar electropathic signature in the thalamus, and a severely decreased histamine count. Victims first disorder would fall suddenly into a coma for approx 72 hours. Diagnosis could be confused by the presence of any of 22 different substances that left electropathic residue resembling that of this disorder.
Irumodic Syndrome: A degenerative disorder that causes progressive deterioration of synaptic pathways. If left untreated it can cause senility and even death. There are treatments but no cure for the disease
Iverson's disease: A chronic disease that causes fatal degeneration of muscular functions in humans
Kalla-Nohra Syndrome : A chronic pulmonary disease found only in individuals exposed to the mining accident at Gallitep 
Lacunar Amnesia : A type of amnesia that occurs when a patient witnesses an act of violence so terrible that the patient rejects the reality of the situation
Microvirus : A genetically engineered virus designed to attack only people with a specific DNA sequence
Neural Metaphasic Shock: in potentially fatal failure of the neurological system in humanoids.
Neural Depletion:  is complete loss of electrochemical energy of a human brain, resulting in the death of a victim. Some species actually derive this energy to digest.
Nitrogen Narcosis : An affliction that affects deep sea divers. It is caused by the replacement of oxygen in oxyhemoglobin with nitrogen. It produces disorientation, hallucinations and lack of judgment
Orb Shadow: Psychedelic reaction to a neuro peptide excess that may follow months to years after an Orb encounter. Associated with Bajoran theology of the Orbs.
Orkett's Syndrome: Childhood hematopathogenic common throughout Bajoran refugee. Among the symptoms was an alteration of erythrocytic marker factors. Thousands of Bajoran children died. The preferred treatment often involved bone marrow transplantation procedures. The disease was common enough to be well-documented.
Parinisti measles : A malady that was an inoculation for Phage A deadly affliction that has decimated the Vidiian race, forcing them to harvest organs from other beings in order to survive 
Polycythemia: An affliction that causes an abnormal increase in red blood cells
Psi 2000 virus : A water-based disease that causes the suppression of inhibitions and is transmitted through sweat hosts
Retrovirus : A Taresian virus capable of implanting Taresian DNA into an alien body which then "overwrites" itself upon the host DNA, thus transforming the host into a Taresian
Rigelian fever A deadly disease that resembles bubonic plague
Rop'ngor: A disease that sometimes affects Klingon children, and is somewhat akin to terrestrial measles
Rudellian Brain Fever: A disease apparently native to Bajor that affects the brain
Sakuro's disease : An extremely rare disease that causes intense fever, weakness, and death if not treated
Somatophysical Failure:  in humanoid physiology, is the collapse of all bodily systems. I'm afraid, to my knowledge, there is little one can do besides Cordrazine and hope. In nearly all cases, the subject dies.
Synthococcus Novae: A bacillus strain organism that is a by-product of modern technology, it is treatable
Symbalene Blood Burn: A virulent disease that can rapidly kill large numbers of people in a short amount of time
T'lokan Schism: The breakdown of mental synapses in Vulcans caused by surfacing of repressed memories
Tahiti Syndrome:  is a term for human longing for a peaceful, idyllic natural setting when suffering from the stresses of modern Starship life. This is common's experienced by Starship Captain, send them into a holodeck every now and then 
Tellerian Death Syndrome A disease that causes cellular decay, symptoms include dizziness, blurred vision & palpitations
Temporal narcosis Delirium produced by exposure to a temporal disturbance
Thelusian Flu: An exotic but harmless rhinovirus
Transporter Psychosis:  is a rare medical disorder caused by a breakdown of neurochemical molecules during transport. Transporter psychosis was first diagnosed in 2209 by researchers. The condition affected the higher brain functions, as well as autonomic systems and body motor functions. Victims were found to suffer from paranoid delusions, multi-infarct dementia. tactile and visual hallucinations, and psychogenic hysteria. Peripheral symptoms included sleepless, accelerated heart rate, myopia, muscular spasms, and dehydration. This problem was eliminated with the development of the multiplex pattern buffer
Tuvan Syndrome:  A degenerative, incurable neurological disease which affects mainly Vulcans, Romulans, and Riggelians. In the very early stages, the patient’s eyelids are slightly displaced, facial muscles are weakened, and respiration is irregular. Loss of motor skills occurs in 10-15 years; life expectancy is 20-25 years. In less then 5 percent of the cases, the disease can accelerate without warning.
Urudelean flu: A mild affliction to which most humans are immune
Vegan Choriomeningitis: A rare and deadly disease with symptoms that include high fever and delirium
Xanthi Fever: An affliction in mature Betazoids that causes them to project their emotional states onto others
Xenopolycethemia: A disease characterized by an abnormal proliferation of red blood cells that cause various symptoms, including weakness, fatigue, enlarged spleen, and pain in the extremities 
Yarim;Fel Syndrome:  A terminal illness affecting Cardassians; it attacks the digestive tract, circulatory and respiratory systems, and cartilaginous tissues. It can be treated with hexagen therapy or neuro-regeneration procedures. There is no cure.