What is Herd Immunity?


When you think of a herd, you probably think of cows, wildebeest or buffalo. In the animal world, there is safety in numbers – more pairs of eyes to look out for predators, for example.

As humans, we don’t generally have to worry about predators, but we can gain the protection of the herd in other ways. “Herd immunity” is the idea that, as long as enough people in a population are immune to a disease (usually through vaccination), they can indirectly protect people who aren’t immune from getting infected.

Dr Adam Kucharski is an Assistant Professor of Epidemiology at the London School of Hygiene and Tropical Medicine, where he works on mathematical models of the spread and control of disease.

Read more about halting epidemics in the latest issue of Microbiology Today. Continue reading

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Streptomyces: bacterial explorers

Streptomyces bacteria are some of the most studied microbes on the planet. This genus of soil-dwelling organisms is best known for being prolific producers of many of the antibiotics that we use clinically. However, despite 70 years of study, they still have secrets left to discover.streptomyces

Researchers from McMaster University in Canada have identified a new kind of growth that occurs in some species of Streptomyces, which enables colonies to quickly explore new areas and climb over tiny rocks, a feat proportional to a human climbing Everest. The group published their findings last month in the journal eLife. Continue reading

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Podcast: Microbes in the Deep Dark Ocean

What’s it like to travel right down to the bottom of the ocean?

6982437095_076f9f2b61_kDeep sea microbiologist Julie Huber should know. Her group, at the Marine Biological Laboratory in Massachusetts, USA, is trying to uncover more about the microbes living in the deepest darkest depths of the ocean. But that’s not all – there are even microbes living thousands of metres beneath the ocean floor itself, within the rocks and sediment.

This is an environment that couldn’t be more different to our world on land – no light, huge pressures, underwater volcanoes and hardly any nutrients. So what kind of microbes do we see living there, and how do they manage to make a living?

Anand Jagatia

Image credit: NOAA Submarine Ring of Fire 2006
Music: Sacred Motion by staRpauSe
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On the Horizon: What is Oropouche virus?

Sloth in the Jungle

In this edition of our On the Horizon series, we take a look at an obscure virus that may cause an important emerging disease in 2017, or may remain in obscurity for much of the world.

That is, except for South America, where the virus is estimated to have caused over 500,000 infections since its discovery in 1955. Its name? Oropouche, named after an area of Trinidad, where it was first isolated from a 24-year-old forest worker. Continue reading

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New to Science: Microbes from raw cow’s milk, corals and millipedes

Each month, the Microbiology Society publishes the International Journal of Systematic and Evolutionary Microbiology (IJSEM), which details newly discovered species of bacteria, fungi and protists. Here are a few of the new species that have been discovered and the places they’ve been found. 

Welcome to 2017! Here are some highlights from the latest issue of IJSEM, published last week.

Scientists from China have isolated a new species of actinomycete from a millipede. The bacterium, which they name Streptomyces kronopolitis, produces chemicals known as phoslactomycins, which could potentially be used as antifungal agents.

Researchers in Thailand have discovered a new microbe in the roots of the Jerusalem artichoke, a plant that produces edible tubers. The microbe, Pseudoxanthomonas helianthi, forms yellow circular colonies – fitting as its plant host is actually a sunflower.

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Antibiotic spider silk that can heal wounds

Spider silk is pretty much the world’s coolest material. It’s extremely flexible, tougher than Kevlar, and weight for weight it’s stronger than steel. If that isn’t enough, there’s even evidence that some spider silks might have antimicrobial properties.

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On the Horizon: Monkeypox

On 8 May 1980, after a global vaccination campaign, the WHO declared that smallpox had been eradicated. Wiping out this viral disease, which has claimed the lives of hundreds of millions of people throughout history, should be considered one of humanity’s greatest achievements. In fact, to date, smallpox is one of only two diseases that we have managed to completely eliminate.

However, this incredible feat has come with some unexpected negative consequences. Just as, centuries before, cowpox virus protected people from getting smallpox, scientists today are discovering that smallpox vaccination may have been preventing the emergence of another related disease: monkeypox. Without the smallpox vaccine to protect people, monkeypox cases are on the rise.

Monkeypox is a member of the genus Orthopoxvirus, and causes similar symptoms to its famous cousin, although thankfully much less severe. Although estimates vary, fatality rates are believed to be less that 10% (compared to around 30% for smallpox). Human-to-human transmission can occur, but is rare. Continue reading

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