Our mosquito bites were infected with wriggling LARVAE

One couple’s story of the nasty holiday souvenir no one wants

At FIRSt, Katie and Ian McCabe assumed the small itchy lumps that appeared on their skin while on holiday in Belize were ordinary insect bites. the couple had gone on a guided jungle walk and — despite using insect repellent and wearing long clothing — they’d unwittingly left a few patches of skin exposed.

‘I got two mosquito bites on my scalp and Katie had one on the back of her neck,’ recalls Ian, 57, a communications engineer. ‘We just assumed they would go away.’

However, the bites slowly grew. And when the couple returned home to Wilmington, Kent, two weeks later, the lumps had taken on another disturbing characteristic.

‘I could feel something moving around inside,’ says Katie, 55, who works with the families of children with autism. ‘As if it was scratching away at the sides.’

By now they had an inkling about what was going on. Before they left Belize last August, the pair had watched a documentary on their hotel tV about the human botfly — an insect whose larvae (or maggots) can live just under human skin.

As part of its life cycle, the fly immobilises a mosquito and attaches eggs to its legs. then when the mosquito feeds on a human, the botfly eggs are deposited under the skin, where they hatch into a maggot.

tiny barbed spikes on its back help anchor it into the skin — Katie thinks it was these spikes on the moving maggot that caused the scratching sensation. ‘As soon as I became aware of it I couldn’t think of anything else,’ she says.

the human botfly is widespread throughout tropical Central and South America, says Dr Anna Checkley, a consultant at the Hospital for tropical Diseases in London. there is a similar creature in Africa called the tumbu fly, but this lays its eggs on the ground or onto washing on a line; eggs then transfer to humans when they sit on the area or put the clothes on.

With the tumbu fly, you can potentially have a number of maggots under the skin. ‘the most I’ve known in one person is 40,’ says Dr Checkley, whose clinic sees at least one British patient a month with a botfly or tumbu fly infection.

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main sign of a botfly infection in humans is a boil-like lump with a pinsized vent on top, which allows the insect to breathe. Waste may ooze from this.

Left alone, the larva will mature under skin for eight to ten weeks and, when it’s about 1.5cm long, drop out and become an adult fly.

But, as Dr Checkley says, ‘most people want to get it out before this stage’. Indeed, Katie and Ian were desperate to rid themselves of the tiny creatures. A search online revealed a slew of stomachchurning videos of people yanking the maggots out with tweezers.

So the pair, who have two children in their 20s, steeled themselves to do the same. First, they dabbed Vaseline on to the lumps, to encourage the maggots to protrude from the hole in search of air. But nothing happened.

the couple should count themselves lucky. experts say DIY attempts to remove the larva are dangerous because you may kill or damage it in the process.

‘You risk getting a painful skin infection, and may need surgery to remove the dead larva tissue,’ says Dr Checkley. ‘they should be removed whole and alive. the key is to see someone experienced.’

For Katie this was easier said than done. When she told the doctor at her GP surgery the following day what was inside the lump, she was greeted with bemusement. ‘She clearly had no idea what I was talking about.’

thankfully, later that day, Katie was summoned back to see another doctor. He admitted ignorance about botfly, but agreed to extract the parasite. Within about 15 minutes, he had removed the maggot through an incision.

‘It was such a relief to be rid of it, and have proof I wasn’t mad,’ says Katie. For Ian, treating the problem was more straightforward. As he works in London, he went straight to the walk-in clinic at the Hospital for tropical Diseases. Here, the lumps were quickly identified and the larvae extracted.

Once they were out, Ian ‘couldn’t believe something so small could cause that much irritation’. the lumps healed quickly after that.

the botfly is one of many hundreds of parasites that can set up home under skin — and many are a hazard in holiday destinations.

One common parasite is strongyloides — a roundworm found in contaminated soil across the tropics. It penetrates skin usually via the feet and travels to the gut. Symptoms can include an itchy, worm- shaped track on the skin that moves a centimetre an hour. Up to 100 patients are treated at the Hospital for tropical Diseases for strongyloides every year.

But patients can live with this parasite for years without realising it. Dr Checkley says: ‘Most parasites have a stage of their life cycle that occurs outside humans — so if left untreated inside you they will eventually die of old age, but strongyloides can keep reproducing inside a human for ever.’ One risk is if a patient’s immune system is compromised — because of steroid medication, say — the parasite starts replicating uncontrollably. this can cause inflammation in the gut and potentially lead to lifethreatening sepsis.

But, usually, it’s the idea of a parasite living within you that is most unnerving. ‘these things are generally treatable; you just need to see a specialist,’ says Dr Checkley.

Mark Farlow, 54, learned this the hard way. He lived with a horribly itchy worm under his skin for weeks before obtaining the drug to kill it. the social worker, from east London, spent a fortnight volunteering in Sierra Leone last October. Near the end of his stay he visited a beach and, soon after, noticed his right foot was intensely itchy. ‘It looked like I had a spider’s web under the skin around the toes, made of fine red lines.’ Back home, Mark saw a chiropodist, who put it down to athlete’s foot and gave him fungal cream. ‘But it just got worse — the rash spread to my left foot as well. Creature discomforts: Ian and Katie in Belize last year I scratched until it was red raw and it woke me at night.’

Finding it hard to bear, Mark went to A&e, where the rash was diagnosed as cutaneous larva migrans (CLM), hookworm larva that normally live in cats or dogs.

In these animals they end up in the gut, where they grow into a worm. But in humans they cannot reach the gut, and instead move under the surface of the skin.

the resulting raised, wiggly rash ‘looks like it’s got a bit lost’, says Dr Checkley, whose clinic sees around 80 cases a year.

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typically catch this parasite while sunbathing on a tropical beach, where cats or dogs have defecated (although the excrement may not be visible).

treatment involves one dose of the worming tablet ivermectin.

After waiting over a week for the drug, Mark went to the Hospital for tropical Diseases, where he received it straight away. ‘ the rash and itch faded a week later.’

the key to preventing infection with strongyloides and CLM is to wear shoes, including on the beach, anywhere tropical. ‘ You should also sunbathe on a towel, and the safest area is below the tide line, as it’s washed twice a day,’ adds Dr Checkley.

to avoid insect-borne parasite bites, wear long sleeves and trousers, use repellents with Deet and sleep under mosquito nets.

Meanwhile, to escape infection by the tumbu fly, Dr Checkley advises ironing all clothes — even underwear. And avoid sitting directly on the ground.

their experience has not put Mark Farlow and the McCabes off travelling. ‘ We had an amazing holiday overall,’ says Ian. FOR more details on the walk-in clinic go to uclh.nhs.uk/HTD