When Mitch was in Afghanistan he got eaten alive by sand fleas and he asked me what they were. As is so often the case I didn’t really know, contrary to popular belief scientists don’t know everything! In fact being a scientist isn’t about knowing everything, it’s about knowing how to find things out. Since I was secretly hoping someone would ask me a question I could blog about I promised to write a post about sand fleas!
The term sand flea causes a lot of confusion as it’s used to refer to several different and totally unrelated invertebrates. If you google it you get a number of articles which are quite confused, initially referring to one type of ‘sand flea’ but then describing features of a different type. If you search wikipedia what you get is a disambiguation page that includes: Talitridae, Sandfly and Chigoe flea as well as Mole Crabs which are actually quite large and not at all flea like!
The only true ‘sand flea’ is the chigoe flea (Tunga penetrans, Jigger or Chigger as it’s also known), it is a flea and it does live in sandy places. Although it’s worth noting that Chigger is also used to refer to a type of mite found in grasslands and forests. I think the over-riding message here is that we need more clarity when people are discussing invertebrates! As is often the case it’s the females that bite and they actually bury their head in your skin and stay there, chomping away and producing eggs. Initially the bite causes an irritation and relatively small bump but as the flea stays in your skin it can cause a blister up to 10mm and this can be quite painful. The blisters have a black dot in the middle – that’s the fly’s behind sticking out so it can lay eggs, breath and poo!
However, these are usually found in sub-Saharan Africa, the Caribbean, Latin America and South America, although I did find one case study from India.
I believe the most likely candidate is a phlebotomine fly (Phlebotomus). There are 96 species and 17 subspecies quite a few of which can be found in Afghanistan but without an adult insect to look at it would be impossible to identify the species. Again it is only the females that feed on blood, this is because eggs contain a lot of protein and so the females need a diet much higher in protein to be able to produce them – I wouldn’t recommend a fly egg omelette though! They often hop about on the host before tucking in which is I guess how they earned the name sand flea. They are small, rarely above 3mm hairy and mostly nocturnal or crepuscular (Active at dawn and dusk). They can be found from sea level up to 3300m in Afghanistan and can be found in soil and vegetation as well as sand.
Phlebotomine flies are a serious concern as some species can carry the parasite that causes leishmaniasis. Leishmaniasis can cause blisters that scar very badly but it can also cause a more severe disease with a fever, swelling of the spleen and liver and anaemia, left untreated this is lethal.
Leishmaniasis is only found in some areas though and it’s only carried by some species, so you don’t need to worry if you’re bitten by something next time you’re on the beach.