Eating Well Could Help Spread Disease, Water Flea Study Suggests

Plentiful food can accelerate the spread of infections, Edinburgh scientists have shown in a study of water fleas.

Scientists studying bacterial infections in tiny water fleas have discovered that increasing their supply of food can speed up the spread of infection. They carried out the study to better understand factors that affect how diseases are transmitted.

Researchers found that when a population of parasite-infected water fleas was well-fed, some of them became highly contagious, compared with when food was limited.

Microscopic image of water flea (Daphnia).

Epidemic spread

"If we have an idea of which individuals transmit a lot of disease, we will be better able to stop its spread," said Dr Pedro Vale, School of Biological Sciences.

Scientists say the discovery highlights that, under certain conditions, some individuals may be more prone to spreading disease than others.

Their findings could help inform ways to monitor and control the spread of infections, such as epidemics, in large populations.

Some well-fed water fleas were more infectious than others because they were able to survive for longer with the parasite, giving it more time to multiply.

Parasite growth

Scientists at the University studied the impact of food quantity on the spread of a bacteria parasite that grows in the water flea gut, releasing infectious spores when the water flea dies.

Among those water fleas that were well-fed, some were found to be carrying many more parasites than others, and so were more prone to spreading the disease.

The study, published in Biology Letters, was supported by the Wellcome Trust and the Centre National de la Recherche Scientifique in France.

"We know that contact between individuals is important; but now we know that, for some animals at least, nutrition may also play an important role in the spread of disease," said Vale.

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