Six penguins have died following an outbreak of malaria at London Zoo.
The birds contracted the avian strain of the disease from mosquitoes, even though zoo keepers had increased the birds' anti-malaria medication due to fears the wet weather would see the insects thrive, according to the BBC.
A London Zoo spokeswoman said avian malaria is "endemic" in the UK's wild bird population and described their penguins' deaths as a "very sad occasion".
She told The Sun: "They have it all the time as a daily dose, given it with their breakfast. We put a tablet in their fish and every single penguin gets one in the morning.
"The keepers also spray lavender oil in the penguins' nest boxes which is a natural deterrent.
"We plant lavender around the enclosure and the penguins use that to build their nests. We do a lot to stop this from happening so obviously it's a very sad occasion."
Avian malaria cannot be passed on to humans, nor can it be passed from bird to bird, and the zoo says the remaining penguins are "healthy and well".
The Humboldt penguins died in August, and the spokeswoman added that no particular species is more at risk than another.
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