What are you taking on your Valentines Day date? Flowers? Chocolates? Clean undies? Don’t forget to pack the insect repellents! There may be more than just “love bugs” about.
I’ve got you under my skin
The human scabies mite (Sarcoptes scabei) is the only arthropod to truly get under our skin. The tiny mite burrows in and feeds on dissolved human tissue in the tunnels they excavate. Itchy yet? Don’t start scratching as that is one way to release mites and infect your friends. The other way is when mites come to the skin surface to mate. Newly “knocked up” females are usually quick to burrow into the skin but for those that don’t, they’re prime candidates for transfer.
Skin to skin contact is the typical way the mites are spread from person to person. A hand shake probably won’t do it but sexual contact will. Serious problems with scabies are also not uncommon in aged care facilities and can be a serious problem in Aboriginal communities. Even wombats can be infected.
Once infected, symptoms can take up to a month to develop. At that point, the infected person develops an allergic reaction to the mite’s faeces, skin moults, saliva or moulting fluids. The “mite tunnels” may appear as pale grey threadlike marks and often follow natural creases in the skin in areas such as the hands, particularly the webbing between the fingers, but also on the wrists, elbows, genitals and breasts. Large areas of the body can also be covered by a rash that is not specifically associated with the mite’s burrows but rather is thought to be a generalised allergic reaction. Severe itching all over the body can be experience with the intensity of irritation especially noticeable at night.
Typical scabies infestations are easily treated with an insecticide cream. Problem is, to confirm infection, you need to have a “skin scraping” taking to look for the mites, their eggs or faeces. Taking a “skin scraping” can be pretty nasty and the bulk of scabies infestations are diagnosed on symptoms alone. I think scabies infection is one of the most over diagnosed illness doing the rounds. From the calls I take (at least a couple a week), anyone who presents to their doctor or pharmacist with an itch appears to end up smearing a cream like this all over themselves. The problem is, when the cream doesn’t fix the itch (because the itch is caused by something other than mites), people may repeat the course of treatment once or twice more (as well as trying “other” solutions). That then leads to self inflicted skin irritation and the cycle continues. Correct diagnosis would avoid these problems!
Scabies infection can be even more serious in immunocompromised or elderly individuals when mite populations explode. Known as “crusted” or “Norwegian” scabies, the skin can take on a thicken appearance and contain huge numbers of mites. In these situations, the condition can be highly contagious and barrier nursing is required.
Intense activity of scabies mite in a case of “crusted” scabies (Photo: Stephen Doggett, Medical Entomology, Pathology West)
The “deadliest catch” on the dating scene or just “butterflies of love”?
Pubic lice, Pthirus pubis, (commonly known as crabs) have found a home on the pubic hair of humans (after apparently making the leap from gorillas around 3.3 million years ago). Different to head lice (Pediculus capitis), the claws of pubic lice are adapted to courser hair pubic region and lice and rarely (but occasionally) travel far from those regions. Unsurprisingly, they spread primarily through sexual contact. In many countries they’re classified as a sexually transmitted infection. However, they don’t really pose a significant health risk. They can cause severe itchiness in the infested regions but there are no known pathogens spread by their bites (interestingly though, there has been some suggestion that the presence of pubic lice may indicate the presence of more serious STIs).
You’ve probably seen the headlines. Prompted by this paper, there has been a lot of attention paid to the rise of the Brazilian waxing trend and the threat it poses to the natural habitat of pubic lice. Are the parasite’s days numbered? This probably isn’t the case. No, probably not.
Although there is some data on prevalence rates in Australia from the 1980s (about 1.5% of individuals visiting STI clinics), there really isn’t much more information available about just how widespread are pubic lice infestations (not much quantitative data on pubic hair trends amongst the general population is available either but there have been some attitudinal studies carried out in Australia). Cases of pubic lice is clearly rare but specimens do occasionally pop up in pathology samples submitted to our laboratory. I once tried to look into some data from local sexual health clinics but there just hasn’t been enough data collected to make any meaningful assessment on any changes in prevalence rates.
These days, with information more readily available online, individuals are probably more likely to buy treatments from chemists than attend sexual health clinics. Avenues to collect reliable data on prevalence rates may be difficult to find. Doesn’t seem to matter anyway as the “Brazillian” trend is apparently over. I can hear the tiny applause of crab claws the world over.
Life cycle of the pubic louse (taken from CDC)
Beware the sleepover stowaways
Bed bugs may not specifically be a sexually transmitted arthropod but nevertheless a parasite that may take advantage of some Valentine’s Day sleepovers. Bed bugs have been grabbing the headlines for the past 10-15 years as that make a stunning resurgence in many parts of the world. This resurgence has been attributed to, in some ways, by greater availability of cheap, fast international travel and resistance in bed bugs to commonly used insecticides (I currently have a PhD student investigating this).
Bed bugs don’t live on the body. They don’t just live in beds either. They live in almost any crack or crevice available that is also close to humans. Bedrooms obviously. Planning a special Valentine’s Day sleepover at the local hotel? Don’t be fooled into thinking bed bugs are only found in cheap accommodation, they’re just as likely to be lurking in five star hotels.
If bed bugs decide to make a meal of you, it isn’t just the bites that cause a problem. If they decide to hide away in your overnight bag, you may find yourself dealing with an expensive and inconvenient pest control operation in your home. Best avoid them in the first place.
Best check for any stowaways in Valentine’s Day gifts too.
Not the souvenir you were hoping for?
Is your partner rushing home from overseas for Valentine’s Day? Make sure they don’t bring home a less than special gift of mosquitoes or mosquito-borne disease!
As highly unusual as it sounds, transporting infected mosquitoes in luggage has been the cause of infections in non-endemic regions. There have been documented cases of “baggage malaria“. Even in Australia, we’ve had a suspected case of “baggage dengue” in Western Australia. While “airport” malaria and dengue cases have been reported in many regions, perhaps the same rapid international travel that appears to be driving the resurgence in bed bugs may increase the risk of baggage-assisted movement of infected mosquitoes?
Even if your partner manages to avoid bringing home any infected mosquitoes, perhaps a passionate reunion could lead to a highly unusual case of sexually transmitted infection. A scientist working in Senegal returned home to Colorado only to infect his wife with the (normally only) mosquito-borne Zika virus (a virus closely related to Japanese encephalitis virus and West Nile virus rarely recorded outside Africa). Interestingly, we’re currently seeing an outbreak of Zika virus in the Pacific so best be warned if your partner has just returned from French Polynesia!
So, does this mean mosquito-borne viruses like Zika, West Nile, dengue or Ross River could be sexually transmitted human-to-human? We know viruses are sexually transmitted between mosquitoes but apart from the case of Zika virus infection discussed here, I’m not aware of any other reported cases in humans. Strange given the huge numbers of cases that occur during dengue outbreaks. Perhaps nobody has thought to check? The semen of boars has been checked and they found Japanese encephalitis virus….
Who would have thought there were so many entomological risks associated with Valentine’s Day?
To find out more about arthropods of public health concern in Australia, check out this document I put together for the Australian Federal Government Department of Health and Aging. It is available for free download as either PDF or WORD versions.
Webb CE, Doggett SL and Russell RC. (2013). Arthropod pests of public health significance in Australia. Department of Health and Aging, Canberra. ISBN: 9781742419770. [PDF]
(Photo of the Alaskan King Red Crab at the top of this post is taken from Wikipedia.)