– Wet weather blamed for creating ideal conditions for mosquitoes
– 58 remaining birds receive specialist treatment
– No other penguins thought to be affected
Penguins at London Zoo have been struck by a deadly strain of malaria that has killed six of the birds.
The outbreak is being put down to the exceptionally wet and muggy summer which created perfect conditions for mosquitoes which spread the disease.
The remaining 58 birds in the colony are being treated daily with specialist drugs supplied by the Hospital for Tropical Diseases to prevent them from contracting the illness as well.
Experts said penguins are particularly vulnerable to the avian form of malaria because they have not built up a resistance to it – unlike many native birds.
Avian malaria cannot be passed to humans, but it kills in the same way – by destroying oxygen carrying red blood cells.
“Penguins come from a part of the world where they wouldn’t have been exposed to malaria. They haven’t had a chance to evolve resistance to it.
“Just like with human malaria the most effective way of controlling it is to stop mosquitoes biting. But we don’t have an equivalent of a bed net for penguins.”
Professor Sheldon said the penguins are likely to have caught malaria after a mosquito bit a native bird with the disease and then passed it on to them.
It cannot be passed directly from bird to bird or to humans.
Zoo keepers at ZSL London zoo are feeding their penguins at breakfast time with the medicine Primaquine, which can also be used to treat the disease in humans.
They have set up mosquito traps in the penguin enclosure and also spray lavender oil in the penguins’ nest boxes to deter mosquitoes. They have also planted lavender which the birds use to build their nests.
A spokeswoman said: “ZSL London Zoo routinely treats its colony of penguins against a strain of avian-malaria which is endemic to the UK wild bird population.
“Due to the exceptionally wet and muggy weather this summer, mosquito numbers were unusually high and ZSL’s keepers and vets decided to increase the penguins’ preventative anti-malarial medicine.
“Sadly, earlier this summer six penguins died of avian-malaria – a different strain to the one that affects humans.
“Avian-malaria is contracted directly from a mosquito bite and cannot be passed between birds.
“ZSL London Zoo’s keepers and vets continue to keep a close eye on the colony and all penguins appear healthy and well.”
She added: “Zoo keepers and vets work closely with our 58 penguins so they are able to quickly recognise any changes in their behaviour and no other birds have been affected by Avian malaria.”
There are very few physical symptoms of avian malaria, which make it difficult to diagnose. Symptoms that sometimes occur include loss of appetite and lethargy and these develop very quickly.
Some people have claimed there has been a rise in avian malaria in recent years due to climate change. But Professor Sheldon said there is not enough evidence to justify these claims.