What's The Deadliest Bacterial Disease?

The World Health Organization hopes to eradicate tuberculosis by 2030. Image credit: www.vicnews.com
  • HIV/AIDS, tuberculosis and malaria kill 6 million people every year; nearly 2 million of those deaths are caused by TB
  • 5,000 people die from tuberculosis every day.
  • If not treated, each person with active tuberculosis infects on average 10 to 15 people each year

Bacteria are found everywhere, in any climate and location throughout the world. While some are airborne, others are most prevalent in water, soil, plants, animals, and even people. Many strains of bacteria are harmless and some are even beneficial, such as those found in the human gastrointestinal tract to aid digestion and produce vitamins. However, there are few (less than 1% of all bacteria types) that cause illness in humans. Some bacteria can be quite dangerous, resulting in salmonella, pneumonia, or meningitis.

The most deadly bacterial disease contracted by human beings is mycobacterium tuberculosis, the world's leading infectious disease with more than 1,700,000 deaths per year. As much as 13% of cases are resistant to most antibiotics, and about 6% are resistant or unresponsive to essentially all treatment.

What is a Bacterial Infection?

Some bacteria are helpful and some are harmful. Photo by CDC on Unsplash

Bacterial infections are caused by harmful strains of bacteria on or inside the human body in any of their three basic shapes: rods (bacilli), spheres (cocci), or helical (spirilla). They cause disease by secreting or excreting toxins (such as botulism), producing toxins internally that are released when the bacteria disintegrate (like typhoid), or inducing sensitivity to antigenic properties (tuberculosis). The severity of the infection and where it occurs depend largely on the type of bacteria contracted by a person.

Bacteria that cause food poisoning like salmonella or E. coli cause distress to the digestive system when a person eats contaminated food or comes into contact with an infected person. They are typically treated or run their course after causing severe symptoms like dehydration, diarrhea, intense cramping, and vomiting. Other strains like methicillin-resistant staphylococcus aureus (MRSA) can infect various parts of the body and can be deadly in people with compromised immune systems. These bacteria are more difficult to treat as they are more resistant to drugs.

For the most part, bacteria target specific parts of the body, meaning it's rare for a strain like syphilis - a sexually-transmitted infection - to be found in the stomach or lungs. Likewise, haemophilus influenza type B causes ear, throat, and lung infections but will not produce bladder infections or skin conditions. Tuberculosis commonly causes severe lung infection, rarely affecting the brain, and is highly contagious.

What is Tuberculosis?

Mycobacterium tuberculosis is slow-growing with waxy walls and devotes most of its cell system to producing enzymes that build up and break down lipids. It is thought to have originated in soil, and some species of the bacteria evolved to inhabit mammals.

It is transmitted between individuals through the air. When an infected person coughs, sneezes, or spits, they send tuberculosis cells into the air and inhaling just a few of the germs can infect another individual. The bacteria, contained in aerosol droplets, attach to the lung's alveola and take root. The severity of tuberculosis infection depends on the overall health and immune system of its host. It may present in different forms, including one that attacks bone and causes skeletal deformities, and one that causes severe lung infection.

What is the History of M. Tuberculosis?

Many unearthed skeletons from ancient Egypt have been found with deformities presumably caused by tuberculosis, which suggests the disease was prevalent among Egyptians who lived 4,000 years ago. Similarly affected bones have also been found in Italy, Denmark, and Middle Eastern countries - proof the disease was not limited to a certain population at the time.

Clay tablets from Assyria in the seventh century B.C., as well as writings by Hippocrates in the fifth century B.C., describe patients wasting away with chest pain and coughing that often produced blood. By the 16th and 17th centuries B.C., tuberculosis had made its way into Europe and caused more than one epidemic. The disease, broadly known as consumption, peaked in the first half of the 19th century after an estimated one-quarter of the European population had died from tuberculosis.

Immigrants from Europe to North America brought tuberculosis with them, though the infection rate was never as high as in the homeland. Larger cities like Boston and New York had death rates of six or seven in 1,000 in the year 1800, but that number declined over the next six decades.

In the 20th century, mortality rates dropped significantly in the developed world thanks to advancements in medicine and widespread use of a vaccine, as well as the introduction of antibiotics in the 1950s. However, by the 1980s the number of cases began climbing again, largely due to increased homelessness and poverty as well as the emergence of AIDS, which compromised immune systems and made tuberculosis hosts more susceptible to severe infection.

Injections of funds to deliver antibiotics to infected individuals in North America and Europe has resulted in a decline in the number of cases to ten in 100,000 people. However, the undeveloped world still suffers from tuberculosis with more than 300 incidences in 100,000 in southern and central Africa.

What is the Mortality Rate?

As many as 2,000,000 people die from tuberculosis each year, equivalent to one death every fifteen seconds. Without treatment, up to 60% of infected people will succumb to tuberculosis infection. Most deaths occur in Third World countries, where poverty and unhealthy living conditions are rampant, and medical care is scarce.

How is Tuberculosis Treated?

Tuberculosis is treatable and curable with antibiotics. Photo by Anastasia Dulgier on Unsplash

The disease is treatable and curable. Antibiotics can be used to treat tuberculosis infections, but because the bacteria can hide inside human cells it is resistant to many medications and most people are required to take four different antibiotics for six months. The most effective first-line antibiotic has proven to be rifampicin, but nearly 500,000 cases per year have shown resistance to its effects.

An estimated 58,000,000 lives were saved from tuberculosis between 2000 and 2008; however, the treatment success rate for tuberculosis is still only 30%, and the drug-resistant strains have spread to more than 123 countries - statistics that prompted the World Health Organization (WHO) to put out calls for new vaccines and drugs. The WHO aims to end tuberculosis by 2030.


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