A quick plug

If anyone's been missing tales of bad weather and body odour in exotic locales, a friend of mine is cycling across South America at the moment. We're running a sweepstake on how long it takes him to become a Colombian drugs baron.

Ever seen a maggot under an electron microscope?

Huhurhur, yur goofy lookin!

Dangers at dusk: is it time to move beyond bednets?

I originally wrote this for The Guardian's "Write the World" International development journalism competition. You can see the winning pieces here, some of which are excellent. I'd particularly recommend "Aid: Dead or alive?" for a more balanced discusion of the benefits and pitfalls of western aid than you usually find in the papers.

Cattle amble lazily back to their night time pastures as the sun sets over the tiny Gambian village of Wellingara. In dusty compound courtyards women stoke the fires that will cook the evening meal of rice and oily stews, while in the streets their husbands wait for their dinner, brewing tooth-achingly sweet attaya tea over charcoal braziers. As the coals smoulder and light-hearted banter or serious matters of village politics fill the evening air you could be forgiven for thinking this was one of the most tranquil places on earth. But all is not as peaceful as it appears.

“You can tell the people who are not from around here because they fight themselves” laughs Tumani, a fieldworker for The Gambia’s Medical Research Council, as he demonstrates how foreigners slap their faces and arms when they feel mosquitoes landing. Locals enjoying the relative cool of the evening know instead to brush the pests from exposed skin, their hands in continuous, fluid motion. Whatever strategies are employed against it though, early evening mosquito biting before people go to bed is a problem which mosquito nets are unable to tackle.

Uptake of bednets in The Gambia has been extraordinarily successful, with almost three quarters of households estimated to own at least one. Although malaria-focussed health education campaigns have doubtless increased their use, like the elaborately carved hardwood beds bought for newlyweds bednets have become something of a status symbol with perceived benefits that go far beyond malaria control. They catch detritus falling from traditional thatched roofs, provide a measure of privacy in a country where large extended families typically share a compound and are appreciated as interior decoration. In the local markets gaudily coloured nets swing in the breeze, adorned with lacy ruffles like some bizarre cross between a jelly fish and a wedding dress. While there are of course caveats – many of the locally produced nets are untreated with insecticides that protect people sleeping against the nets from bites, and the youngest children most vulnerable to malaria may not be the ones sleeping under the nets – with malaria infections and deaths in decline in The Gambia, this tiny country provides an encouraging example of what could be achieved by widespread adoption of insecticide-treated bednets.

Unfortunately it seems that in some areas bednets are becoming victims of their own success. The most effective nets are those treated with pyrethroid insecticides, but in some parts of Africa populations of mosquitoes are evolving resistance to pyrethroids and as treated nets become more common resistance will offer a greater survival advantage and so is likely to spread through the population.

Concerns are also emerging that malarial mosquitoes may be changing their behaviour to bite earlier in the evening before people are protected by nets. To complicate matters humans are also changing their behaviour; particularly in urban areas where development may bring electric light and flickering televisions beaming Brazilian telenovelas or Kung Fu movies to rapt audiences, people are staying up later after sundown and remaining exposed to mosquitoes for longer. Taking into consideration the fact that malaria is not the only disease transmitted by mosquitoes - the species that transmits yellow fever, for example, is active at dusk – the importance of preventing early evening biting becomes increasingly apparent.

Large-scale mosquito control programmes, such as those treating water sources where mosquitoes breed with chemical or biological insecticides, have had impressive results in some areas but require a great deal of political will, organisation and stability to scale up and so may not be appropriate everywhere. Instead the use of repellents, chemicals that smell unpleasant to mosquitoes, is being suggested as an approach that can be targeted at the household level as bednets can.

Tourists and travellers visiting malaria-endemic areas have long protected themselves with DEET, the plastic-melting personal repellent that can be rubbed on skin, and with the development of gentler personal repellents such as those derived from lemon eucalyptus oil there has been interest in extending the benefits to the local population. This work is in its early stages, but results from work in Bolivia on the effects of personal repellents in addition to nets are encouraging. However, as campaigns to promote handwashing with soap in Africa have shown, encouraging a change in habits is difficult and attempting to foster a culture of repellent use from scratch where none existed before would be challenging to say the least.

Another approach is the use of spatial repellents, odorous chemicals which disperse and so could make a wide area, for example the veranda of a house, unattractive to mosquitoes. Here signs are perhaps more encouraging; families in The Gambia already regularly burn mosquito coils or local herbs to deter evening biting insects, and as our knowledge of mosquito behaviour and biology increases we will be increasingly well placed to evaluate the effectiveness of these particular blends and to design new mixtures of odours and methods of delivering them.

Of course the use of repellents may simply provide a different pressure for mosquito populations to evolve their way around. Peaceful as the streets of Wellingara may appear as the tropical sun slips below the horizon, in the ongoing war between humans and mosquitoes they are in fact a battle ground.

Home

I isolate the individual odours attractive to my flies from a complicated blend using a process called chromatography. Although this is done at Rothamsted with a fancy piece of equipment the basic principle is very simple: you have two different substances or "phases" which have different affinities for the different components of the blend you're trying to separate. The mobile phase, a gas or liquid, is passed over the stationary phase which could be a polymer or wax. Things with a greater affinity for the mobile phase will spend a greater proportion of the time in it, so will come out of the system faster than things with a greater affinity for the stationary phase. Use a long enough system and different constituents of a mixture will reliably come out separately, one after another.

The random chemistry lesson comes courtesy of a brilliant demonstration of the principles of chromatography that I saw at Gatwick airport on the way home. A mixed crowd of Gambians and British people got off the plane and started walking through the terminal building. We all walked together until we reached the first moving walkway, which interestingly the British people got on but the Gambians didn't. Three walkways later, the airport-sized chromatography system had acheived perfect of a mixed group of human beings on the basis of nationality with the Brits emerging 50 metres ahead of the Gambians.

So now I'm home, with my bloke and my family and my knitting and my tea and my 24 hour amenities and I'd be lying if I said it was anything other than a huge relief. Apologies to everyone I haven't been in touch with yet, I've needed a little time to recover but I plan to get in touch with all of you very soon. And everyone I have managed to speak to, even if it's just on facebook, thanks for the lovely welcome.

I think Hounslow Borough Council also wanted to welcome me back, I got home to find this poster on the bus stop on our street!

Photo time!

I've got my photos up on Picasa:

The international language of suspicion

So I'm back down on the coast, with a few samples, a few pupae that I hope are still alive and the majority of my marbles. I've just come back from visiting my fieldworker D's wife, daughter and extended family who touchingly and quite out of the blue presented me with a dress for myself and a shirt for the bloke.

The Gambia is so different from everything I'm used to that it sometimes feels like I've landed on a different planet, until something startles me into realising just how connected we all are. Meeting D's wife's aunt, who dresses like a traditional village wife and speaks flawless English after living in Bromley for two years, was one such event but the person who really surprised me was D's brother in law, a school headmaster. We got talking about how I'd get back to the hotel, D explaining that he would accompany me in the taxi, a plan which the headmaster approved of. He then announced, and I quote pretty much word for word:

"It is good that you are going with her because it is not safe now in The Gambia. Before it was safe for a woman at night but now they let anybody into the country, all these Senegalese and Nigerians. Sometimes now I go into Banjul and all I hear are languages that I don't understand."

I burst out laughing, a bit of a courtesy fail that I had to talk myself out of, but I think that just goes to show that whatever our cultural difference people all over the world are all the same. We're all so frightened of each other but even the more prejudiced members of society are prejudiced in exactly the same way.

That's about as philosophical as I get when sleep deprived, high on Coca Cola and demob happy, so I'll leave you with that thought and try to finally get some sleep. Night all.

Nightmares

Fun day yesterday, it was so hot you could actually watch beads of sweat forming on your skin and the generator exploded. Actually, genuinely exploded – Sarah, one of the MSc students had to put out the fire and in doing so discovered that the fire extinguisher had already been discharged. A miscommunication with the guards sent me and D off yomping round town to try and sort out a problem with the NAWEC (National Water and Electricity Company) that didn't actually exist, and to top it all off one of the kittens is missing and has been for several days, presumed... well not presumed anything good anyway. Just about the only thing going well here at the moment are the sores on Mission's ears – I didn't expect the antibiotic powder to do much but they're about half the size they were when I arrived. He may even be ready for a photo before I go (I know they'll just get worse again when I leave, but at least I can give the poor dog some relief for a short time).

In the evening wrote a long email to my supervisor, summarising how my work had been going (badly) and the internet cut out as I was sending it – I lost the whole thing. So I decided it was finally time for the five tiny strips of streaky bacon the students had picked up for me in Senegal, that I'd been saving for when things got really bad and cooked this:

And incidentally facilitated cannibalism in the process, by unthinkingly lobbing the plate of peelings over the wall to the pigs the way I usually do and forgetting there was bacon rind on there too. So I cut my losses and got an early night.

A few hours later I woke up, needing to visit the toilet to give the mosquitoes their midnight snack. Getting back into bed by the dim illumination of the security lights is always tricky - I don't know if you've ever seen that daft film in which Catherine Zeta-Jones writhes around in a catsuit to dodge laser beams, but if you imagine a mosquito net that has inexplicably multiplied overnight into a dozen layers instead of laser beams and me with a sweat-stained t-shirt and hair like a refugee from the eighties instead of CZJ in a catsuit you'll get the picture. I'd managed to get inside from the waist up and was leaning on my hands to pull my legs in when something largish and indistinct in the feeble light darted across the sheet and came to rest against my hand.

My heart started beating like that of the average teenage audience member watching CZJ writhe in the catsuit, but I didn't move my hand ("Must...not...disturb whatever it is, spider? Baby scorpion? World's largest tick? It doesn't seem to be biting me yet. WTF is is???"). Instead I cautiously, slowly reached for my torch with the other hand, flicked it on and carefully moved the circle of light closer so as not to startle the...... @(**$%@ing rubber earplug that had rolled across the sheet into the depression made by my hand (I keep the box inside the net with me to be easily accessible in the event of enthusiastic mosques or rams, and it had come open). I wasn't sure whether to laugh or cry so I settled for passing out asleep instead, falling into feverish dreams in which the person I'd expected to most disapprove of my involvement with Mission was paying to bring him over to the UK and helping me to choose a crate for him for the flight. I think all things considered that if my subconscious is going to torment me with anything I'd rather it was phantom insects.