BLACK DEATH

The Black Death was one of the most devastating pandemics in human history, resulting in the deaths of an estimated 75 to 200 million people and peaking in Europe in the years 1346–1353.Although there were several competing theories as to the etiology of the black death, analysis of DNA from victims in northern and southern Europe published in 2010 and 2011 indicates that the pathogen responsible was the Yersinia pestis bacterium, probably causing several forms of plague.

Origins of the disease

The Black Death is thought to have originated in the arid plains of Central Asia, where it then travelled along the Silk Road, reaching the Crimea by 1343.From there, it was most likely carried by Oriental rat fleas living on the black rats that were regular passengers on merchant ships. Spreading throughout the Mediterranean and Europe, the Black Death is estimated to have killed 30 to 60% of Europe's total population.In total, the plague reduced the world population from an estimated 450 million down to 350–375 million in the 14th century.

Symptoms

Contemporary accounts of the plague are often varied or imprecise. The most commonly noted symptom was the appearance of buboes or gavocciolos in the groin, the neck and armpits,which oozed pus and bled when opened.


A hand showing how acral gangrene of the fingers due to bubonic plague causes the skin and flesh to die and turn black.

Chikungunya (Malaysia)

Chikungunya fever is a viral disease transmitted to humans by the bite of infected mosquitoes. Chikungunya virus is a member of the alphavirus genus, in the family Togaviridae. Chikungunya fever is diagnosed based on symptoms, physical findings, laboratory testing, and the possibility of exposure to infected mosquitoes.

Symptoms

Chikungunya virus infection can cause a debilitating illness, most often characterized by fever, headache, fatigue, nausea, vomiting, muscle pain, rash, and joint pain. The term ‘chikungunya’ means ‘that which bends up’ in the Kimakonde language of Mozambique.

Can Chikungunya cause death?

In Malaysia, Chikungunya has never been reported as causing haemorrhage bleeding or death. However, some patients experience prolonged symptoms. Aged patients could suffer from recurrent joint aches ranging from several months to a year.

Vaccine

Currently, no approved vaccines are available. A phase-II vaccine trial used a live, attenuated virus, to develop viral resistance in 98% of those tested after 28 days and 85% still showed resistance after one year.However, 8% of people reported transient joint pain,and attenuation was found to be due to only two mutations in the E2 glycoprotein.Alternative vaccine strategies have been developed, and show efficacy in mouse models, but have so far not reached clinical trials.

BLIGHT DISEASE 

Blight refers to a specific symptom affecting the plant in response to infection by a pathogenic organism.It is simply a rapid and complete chlorosis, browning, then death of plant tissues such as leaves, branches, twigs or floral organs.
Many diseases that primarily exhibit this symptom are called blights

Notable examples are:

Late blight of potato, caused by the water mold.Phytophthora infestans Mont de Bary, the disease which led to the Great Irish Famine

DIFFERENT TYPE PF PLAGUE

Bubonic Plague

When a flea bites a human and contaminates the wound with regurgitated blood, the plague carrying bacteria are passed into the tissue.Y. pestis can reproduce inside cells, so even if phagocytosed, they can still survive. Once in the body,the bacteria can enter the lymphatic system, which drains interstitial fluid. Plague bacteria secrete several toxins, one of which is known to cause dangerous beta-adrenergic blockade.

Septicemic Plague

Lymphatics ultimately drain into the bloodstream, so the plague bacteria may enter the blood and travel to almost any part of the body. In septicemic plague, bacterial endotoxins cause disseminated intravascular coagulation DIC, causing tiny clots throughout the body and possibly ischaemic necrosis tissue death due to lack of circulation/perfusion to that tissue from the clots.DIC results in depletion of the body's clotting resources,so that it can no longer control bleeding. 

Pneumonic Plague

The pneumonic form of plague arises from infection of the lungs. It causes coughing and sneezing and thereby produces airborne droplets that contain bacterial cells and are likely to infect anyone inhaling them. The incubation period for pneumonic plague is short, usually two to four days, but sometimes just a few hours. 

Pharyngeal plague

This is an uncommon form of plague that resembles tonsillitis found in cases of close contact of patients with other forms of plague.

Meningeal Plague

This form of plague occurs when bacteria cross the blood-brain barrier, leading to infectious meningitis.