They say travel helps you suck the marrow out of life. Well, if you plan to visit Asia, particularly Southeast Asia, then prepare for a few leeches to try and suck the life out of you. And while it may sound yucky and gross, it’s not as bad as it seems, especially with a little preparation. And did I mention the birding is totally worth it? I find leeches absolutely fascinating, equally so people’s reactions to them. So I’ve decided to dedicate this post to LEECHES in deference to their importance in the ecosystem and in the psyche of the traveling birder.
Long live the leech!
The haemadipsids, or as they are commonly known, the “jawed land leeches,” are terrestrial, parasitic, blood-feeding leeches and are most common in Southeast Asia and Australia. Many different species jawed land leeches exist. And then there are other leech families, which are mostly aquatic and have a global distribution. The heamadipsids have five pairs of eyes and two to three jaws. The jaws look like tiny half-circular saw blades and are extremely sharp and have either small teeth or a cutting edge. The two-jawed species leave a V-shaped bite and the three-jawed ones leave a Y-shaped bite (are you still with me?). These bloodsuckers use these jaws to bite their temporary hosts. They will feed on all types of vertebrates, including humans (how about now? It gets better, I promise).
The sanguinivorous (i.e., bloodsucking) leeches that I am most familiar with in Asia have a substance called hirudin in their saliva, which is an anticoagulant. So when a leech bites you, expect to bleed long after it’s had its fill. Generally speaking the bites do not hurt – it is thought that they have a mild anaesthetic in the saliva. Some leeches certainly don’t use an anaesthetic and possibly have larger mouthparts. The leeches at Da Lat in Vietnam for example are, for some reason, particularly painful. The upside is that by giving themselves away, they are easy to remove.
Leeches tend to be more prevalent after rain but my clients and I have an ongoing controversy about which person in a group is most likely to be bitten – the leader on a trail or the followers. My considered opinion is that the front person cops the brunt but those at the back tend to disagree! So the jury is still out.
There are two common questions asked about leeches – how do leeches know you are coming and do they spread disease? Neither of these are easy to answer. Regarding the latter question, the straight answer is easy – no, they definitely don’t lead to serious disease though some may cause temporary infection. So you can rest easy and book that flight to Thailand. But if you have an enquiring mind, you might ask “why not?” I am still researching the answer to that one. It may be because they are thought to feed infrequently, possibly only once or twice a year and so any pathogens they ingest are already dead by the time they attach to the next host.
The former question has a couple of answers. Leeches are responsive to light and mechanical stimuli. They can detect movement, so if you brush against a tree or tread heavily they will feel, rather than hear, you coming. Secondly, they are outfitted with heat receptors and can detect humans by their body temperature.
Another cool fact is that leeches easily dry out and once they do will enter into a torpid state. But, wa-la, just add water and they will rapidly spring into action!
How to remove leeches, or better yet, how to avoid them
If you find a leech attached to your body DO NOT PANIC. The little guy only wants to sip a tiny bit of blood, and while it may look revolting and make a bloody mess, is it really worth missing that rare skulker or new pitta because of a leech?! Certainly not!
Now, there are a few ways of getting rid of your leech. You can simply wait till it drops off, thereby avoiding touching the slimy thing and, after all, once it’s attached it makes no difference when you remove it. You can also resort to chemical means – anything that the leech won’t like such as vinegar, lemon juice, salt, fire or tiger balm (or equivalent). By the way, fire, such as a lit match or cigarette, should be avoided – you could end up with far worse injuries than those sustained from the leech. Tiger balm is useful because it is easy to carry in your pocket, it’s not messy and the leeches hate it. The trouble with all these things is that there is a risk of the leech regurgitating into the wound leading to infection.
The best method is to simply pull it off using your fingernail to dislodge the sucker from the skin and then flick it away. Also, be sure to keep the wound clean and use a bandage to stem the bleeding.
I have been to some amazingly leech-infested places. I’ve seen them so thick on the ground, you can literally hear them crawling towards you. Two good places to see leeches include Danum Valley Conservation Area (Malaysia) and Khao Yai National Park (Thailand). But don’t let this stop you from travelling to these hotbeds of biodiversity, there is an excellent way of avoiding leeches (almost) altogether: leech-proof socks.
I used to scoff at leech-proof socks believing that leeches should just be ignored. Over the years, though, and after many bites, it seems that you develop a bit of a reaction to leech bites and the itching can be very irritating. Also, the potential for infection should not be underestimated; this can be a real problem in the tropics especially as most bites will occur around the ankle area where shoes and socks tend to rub. Most leeches can easily tunnel through the weave of ordinary socks so leech-proof socks are the best way of denying access to bare skin. The socks are basically sock-shaped pieces of fine-woven material (such as calico) that are worn over regular socks and under the boot. They are long with a pull-tie at the top, which ties up firmly under the kneecap and above the calf. If the leeches are particularly bad, it may be necessary to spray the boot and sock with an insect repellent; otherwise, they will simply climb up your leg to the nearest point of entry. The socks won’t make you 100% immune to the problem as the leeches may also climb on to you from overhanging vegetation and can attach around your waist or neck. Trip leaders tend to be well aware of the local severity of leeches and will advise you how to dress. If you’re travelling alone, however, always tuck in your shirt and never leave your shirt collar agape.
How to treat a leech bite
Keep the wound clean. Wash with soap and water and dry thoroughly then apply pressure at the point and wait to the bleeding stops. There is a strong possibility that the bite will start to itch after a day or so and if you have a few bites around the ankle this can irritate the problem.
My favorite remedy is tiger balm or balsam hijau (which is even better but harder to find) from Indonesia. There are a number of anti-itch concoctions available from chemists and these work almost as well. If the bite is severe, it may be necessary to use antihistamine. Of course, if the bites become infected then the best course of action is to consult a doctor.
It’s all in your head
As you can see, sucking the marrow out of life has its ups and downs. But I assure you, go prepared and the upside of traveling to Southeast Asia will far outweigh the downs.
Do you have any leech stories or advice? Tell us in the comments.