The word ‘malaria’, a conjoining of the Italian mala aria meaning bad air, has cropped up repeatedly in the news lately due to a certain celebrity contracting a vicious strain of Plasmodium falciparum while on holiday in Tanzania. She is now recovering but only after intensive treatment at the London Hospital for Tropical Diseases. Yes it is important to keep on taking those anti-malarials after we return home. She may also, of course, have contracted a resistant strain.

The relationship between this parasite, which is a protozoan, and humankind is as old as our evolutionary history. It was almost certainly in the great apes from which we evolved and has been with us ever since. Alongside the parasite and ourselves the third member of this Darwinian triangle, the anopheline mosquito, has also shadowed us, inside and outside our dwellings, becoming more anthropophilic in its biting habits until for particular species we are not only a nice additional meal but by far the preferred one. After all there has been an ever growing number of us in the world. To study these relationships in depth, which it has been my privilege to do in the past, is to be not only horrified at the historical human toll of the disease, but also to be profoundly struck by the beautiful intricacies of biology.

A female anopheline in flight, weighed down somewhat by her recent blood meal. For those who wish to tell the difference between male and female mosquitoes, because the males will not bite you, it is easy. Look at the antennae. If they look like a bog brush you are looking at a male. If they are virtually without bristles as in the above picture, you are looking at a female and watch out because she is probably looking at you too. If you see one on the wall of your Greek island apartment she is almost certainly a she because she has come in specially to say hello. If she has her bottom in the air then she is an Anopheles. It is part of her culture. If she is flat against the wall she is likely to be Aedes or Culex, neither of which transmit malaria, but in the tropics might give you yellow fever or elephantiasis instead. The mosquito continues to bequeath us many gifts.

The form the disease takes in us is well known. It is characterised by periodic fevers which occur when the parasite bursts out of red blood cells, alien-wise, in order to reinfect yet more red cells. This happens every 48 hours, except in the case of the species Plasmodium malariae, where the fever cycle is 72 hours. There is also a liver stage where the parasite holes up for a while after you are infected by a bite from the mosquito. In the case of Plasmodium vivax, which is sneaky, it keeps a few copies of itself in the liver, storming out from time to time, to begin again the nasty blood cell stage. Relapsing malaria is more debilitating than deadly but in combination with other factors can be a significant contributor to early death. Plasmodium malariae is also sneaky, but in a different way, maintaining itself at very low levels in the blood, under the radar of the immune system, and like vivax can cause relapses. The tropical falciparum, which the certain celebrity I mentioned has been lucky to survive, is aggressive in its blood stage beyond all reason. The ‘parasitaemia’, that is percentage parasite load, can reach very high levels and the red cells become ‘sticky’ getting caught where they shouldn’t and causing blockages with severe consequences, the least of which is death.

What is not so well known is that malaria was endemic throughout much of Europe right up until the 1950s. The Anopheles vectors are still with us. There are probably a number in your garden right now. Particularly if you have a rain water butt. They do like somewhere nice and watery to lay their eggs. In the Middle Ages the disease was commonly known as the ‘ague’, although this described so many febrile illnesses that specifics are hard to pin down. It is thought that many infections in these times were likely to be due to Plasmodium vivax. What is certain is that malaria would have been an illness the Anglo-Saxons were familiar with, particularly in Southern England, and especially around fenland or marshy brackish inlets. It would have been a seasonal burden that would load down a man and prevent him planting the crops. Years of relapses would eventually take their toll on your grandmother. It would kill your new born son or daughter.

Bald’s Leechbook (9th century) contains references to febrile illnesses that are almost certain to be malaria. The difference between tertian (48hr) and quartan (72 hr) fevers is noted as is the fact that relapses often occur in the spring. Life threatening symptoms are described such as splenomegaly (enlarged spleen) and severe anaemia. Shivering and cold sweats (colan feforas) are mentioned. Sometimes it is called ‘half-dead disease’. The fenlands and marshes of England had a fearsome reputation. Hilda Ellis-Davidson famously suggested that the monster Grendel was a symbol of a predatory fenland illness. St Cuthbert back in the day also claimed that the marshes were haunted by the ‘evil seed of Cain’. A description of Grendel that occurs in Beowulf.

The best text I know that contains superb translations of Bald’s leechbooks, the Old English Herbarium, and the Lacnunga manuscript together with as much erudite detail about the Anglo-Saxon healing tradition as you would want in a lifetime is ‘Leechcraft’ by Stephen Pollington. In this book Stephen has truly given something to the nation. I have it in hardback and it cost me a packet from Anglo-Saxon books. I don’t know if it is now available in soft cover but it should be. In his book Stephen makes a reference also to ‘spring sickness’ (lencten adl) and attributes its likely cause to malaria. He is sceptical about the symbolism of Grendel but admits to a striking imagery of ‘cleansing’. What I like about it as a possible symbol though, even if it is dated, is that it renders modern interpretations that seem obsessed with anachronistically censuring Beowulf’s heroic concerns and giving the monster’s ‘side’, as rather absurd. One might suggest that Plasmodium has as much right as us to be here, but it is a view that becomes more difficult to sustain when you are losing family members.

I return to biology and mix it a little with history, in the same way that the estuaries of East Anglia are mixed with salt, because there it seems likely that the main vector of malaria in Anglo-Saxon times and later was Anopheles atroparvus, the eggs and larvae of which have a high tolerance for salinity.

There are now research grants to be had for the study of malaria in relation to climate change as rising temperatures might favour its spread. There is also a growing reservoir of infection in returned travellers. It seems unlikely that the pool will ever be big enough for our local Anopheles to pick it up again in serious numbers but we should be vigilant. After its success with smallpox the WHO declared decades ago that malaria was next. The WHO severely underestimated both the parasite and its vector, each of which compared to smallpox in terms of evolutionary cleverness is like Stephen Hawking compared to … well you fill in the blank with your favourite dumb-bell …

The object for the WHO is now ‘containment’. We are always hearing about a new drug or vaccine for malaria only for things to go quiet again. Resistance of both parasite to drugs and the mosquito to insecticides and the hydra-like head of the protozoan in regard to new strains which evade vaccines are legendary. Sometimes a simple cheap solution is all that is needed to help a population in its battle with one of our oldest enemies. A handing out of free mosquito nets or a drainage programme. As usual charities are doing what they can but it is sad to reflect that in Africa this menace is still responsible for around a million infant deaths a year and is now complicated by AIDS.