12 Of The World's Deadliest Diseases

As news of the spreading Ebola virus is reported around the world, the threat posed to thousands of people across several continents is becoming clear. The terrible effects of the disease may be shocking, but a review of history suggests that the emergence of a pandemic with a global scope is anything but unusual.

Though significant scientific and medical advances mean that many long-standing diseases are technically treatable, recent years and decades have shown the persistent problem of poor social conditions in exacerbating epidemics which have broken out. For many living in poorer countries and socially disadvantaged areas, medical treatment to combat viruses may simply not be available. Yet, the cost of allowing such conditions to remain are great. Given the unprecedented inter-connectedness of modern-day economic life, and the growing virulence of some viruses, a disease which at first appears to be a local or regional challenge, can very rapidly expand to pose a global danger. In no particular order, the following list indicates some of the deadliest diseases, almost all of which continue to be present today.

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12 Cholera


Though a long-standing problem in India, cholera emerged as a truly global threat in the 19th century. The spread of the water-borne disease was related to a combination of factors, including the expansion of trade and economic activity, as well as changing living patterns. Global trade meant that the disease was transmitted across continents and claimed many lives, even in the most advanced countries. The high number of deaths was also attributable to the concentration of more people in cities, as a consequence of the industrial revolution. Often living in poorly ventilated, overcrowded and inadequate housing, those living in the inner cities provided the ideal environment for Cholera to run rampant. For example, in London in 1832, 55,000 people lost their lives, and during 1867, over 100,000 people died in Italy. The disease remains a problem today, however, generally only in developing countries.

11 Dengue Fever


An infection common in tropical countries, Dengue Fever has been known about for several hundred years. Efforts were begun early in the 20th century to develop a vaccine to cure the virus, which is spread to humans from mosquitoes. Projections suggest that anywhere from 50 to 100 million are infected by the condition annually, and that out of these, 25,000 will die. Trials continue to identify a possible cure. At the beginning of 2014, reports stated that testing remained in the human efficacy stage.



Severe Acute Respiratory Syndrome (SARS) emerged in 2003, developing into a serious public health crisis in China and later, internationally. SARS is believed to have originated in animals and represented a new type of virus. It infected more than 7,000 people in 2003 and was responsible for the deaths of over 500. In Canada, Toronto was struck by the most serious outbreak outside of Asia, resulting in 32 deaths by June 2003, and the WHO issued a travel advisory warning against travel to the city.

9 Spanish Flu


As if four years of all-out war were not enough, Europe and America were struck by the Spanish flu virus in 1918. The pandemic lasted almost two years, targeting young adults who had the strongest immune systems. The devastation brought by the virus was extensive, with estimates putting the dead at between 20 and 50 million. To put this into perspective, projections of the number of military deaths in the First World War, which had just concluded, are over 16 million. Research continues into the specific properties of the flu strain which broke out in 1918, in order to better understand and deal with a future pandemic.

8 Ebola


Since its discovery in the mid 1970s, the disease remained confined overwhelmingly to rural areas of west Africa. Until this year, that is. The disease is spread by infected bodily fluids. The dramatic speed with which Ebola has broken out of its traditional regions is posing severe dangers to public health, not only in the three west African countries currently baring the brunt of the epidemic, but also throughout the world. Some countries, like Canada and Australia, have responded by closing their borders to travellers from the region. There are several efforts under way to produce a vaccine capable of treating the illness, and some of the initial results are expected in the coming months. To date, the current outbreak has killed over 5,000 people in west Africa, according to the World Health Organisation (WHO).

7 Lassa Fever


Victims of Lassa Fever exhibit Ebola-like symptoms. Discovered in the late 1960’s, it’s yet another disease with its origins in west Africa. To date, working on a cure has not made it beyond the early testing stages. Causing roughly 5,000 deaths per year and accounting for between 300,000 and 500,000 cases, the danger posed by Lassa Fever is considerable.

6 Bird Flu


The H5N1 strain of flu, better known as avian or bird flu, is so called because it first emerged in poultry stocks in Asia. In 2005, public health organizations warned of a global pandemic as the virus began to spread outside of the Asian region, reaching Europe. Although the number of cases of human deaths continue to be relatively low at several hundred, the fear remains that H5N1 could become much more dangerous if it mutates, thus enabling the transmission of the virus between humans.

5 Winter Flu


It may surprise you to know while reading about some of the most deadly diseases that seasonal flu is one of them. Although vaccinations against the threat of flu are widely available, a steady number of cases, some of which result in death, occur each year. In Canada, since 2009, there has not been a winter in which less than 100 deaths have been recorded, with the lowest figure being 104 in 2011-12. The elderly, children and people with weakened immune systems are most often targeted. But in 2009-10, as a result of the H1N1 strain, broader layers of the population were infected and the number of deaths rose.

4 Smallpox


The only disease on this list that no longer threatens our health, Smallpox was eradicated entirely through sustained international collaboration in vaccination programs in the 1970s. But prior to that, it had been the scourge of many societies throughout history. The last reported death from Smallpox came, curiously enough, in 1978 in Birmingham, England, following a laboratory accident which produced a mini-outbreak.



Believed to have originated in west Africa, HIV/AIDS gained increasing prominence as it spread globally. The virus gradually weakens the immune system with the result that many sufferers die as a result of another infection, which they are incapable of fighting off. Although drugs are available to treat the condition, they are often hard to obtain in some of the areas worst affected, such as sub-Saharan Africa. One of the countries impacted most severely is South Africa, where according to figures published by the department of health in 2012, 29.5 percent of mothers attending antenatal clinics had HIV. It is thought that approximately 40 million people are living with the condition globally, many of whom are unaware of their condition.

2 Tuberculosis


Linked with malnutrition and overcrowding, TB is yet another disease which has a disproportionate impact upon the poor. It is spread by the breathing in of bacteria, is extremely contagious, and its presence is not always apparent. This is because people can either be infected with latent or active TB. Though the latent variety will not make you feel sick, the bacteria can become active at any time. The disease’s severe impact over the years is reflected by its frequent portrayal in various literary works. It was referred to by Dickens in Nicolas Nickelby as the “dread disease,” and made a regular appearance in Russian novels of the 19th century. TB is further complicated by its links to other viruses, the main one being HIV/AIDS. A significant percentage of those suffering from HIV also have TB, and the disease is at least three times more likely to become active in people with HIV.

1 Diarrhoeal Diseases


Despite being both preventable and treatable, diarrhoea remains the second most common cause of death for children under the age of five, globally. Figures in 2012 attributed over a million deaths to diarrhoea, and a total number of 1.7 billion cases. It thrives in environments with dirty drinking water and a lack of sanitation, meaning that developing countries are at high risk.

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