Jungle Microbes

Q&A

Dr. Kevin Kain, Director of the McLaughlin-Rotman Centre for Global Health and the Centre for Travel and Tropical Medicine at Toronto General Hospital

Outpost: What’s the difference between parasites and other microbes?

Dr. Kevin Kain: A parasite is more like a human. It has a cell that looks like mammalian cells and has more genetic horsepower than a virus or bacteria. It has a lot more genes. Viruses sometimes have only 10, but [the parasite] that causes malaria has 5,000, which means it’s much smarter at figuring out how to outfox your immune system…Parasites [also have] different life stages. If a vaccine only kills one life stage, the parasite just flips to the next one…[They also] shed. If they have a surface coat and your immune system starts to recognize that coat to kill it, they just change it…Some [parasites] are quite challenging to treat, like the guinea worm, which is about a metre long…If you put your foot in water and the head pops out, you have to wrap it around a match stick and it can take weeks to pull out.

OP: Should travellers get tested for these infections when they return?

KK: Anyone who has travelled in an exotic destination for more than a month, [has] spent a long time backpacking or [has] been an expat in sub-Saharan Africa or rural Asia might be screened. There are some serious parasitic infections, and if we find them we can get rid of them easily. If they’re not looked for, they can stay in your body for your whole life, wait until your immune system takes a beating, [then] all of a sudden be life threatening.

OP: Fever is the big indicator of serious infection, correct?

KK: Yes. Fever needs to be dealt with urgently. If it’s Friday, you can’t wait until Monday to see if it’s going to go away. If you’re in the tropics and have a fever, assume it’s malaria. And be an advocate, tell a doctor, “I think it can be malaria.”

OP: Does DEET repel all insects?

KK: It has the most effect on mosquitoes and a decreasing effect on other insects. It’s not very effective against tsetse flies. Permethrin [an insecticide] works on most insects…So for people who are going to be in the bush or on safari, it’s not a bad idea [to bring permethrin].

OP: We know DEET is very effective—but some people don’t like it.

KK: It’s pretty safe, despite the way it smells, and it’s surprisingly not toxic, even though it has a weird sounding chemical name. But it’s been used by two billion people and the number of serious side effects has been incredibly small. If people don’t like it, there is a new and effective mosquito repellent called picaridin. It’s been in Europe for a while and has just been approved in the United States. It goes under the name Bayrepel or Autan and doesn’t have the smell or do the things to plastic and synthetics [that DEET can do].

OP: What’s your opinion on the claim that Vitamin B1 or citronella-based products are effective repellents?

KK: It’s not just opinion. There’ve been trials on B1 and it has no measurable effect on preventing mosquito bites! Citronella does inhibit bites, but not very well, and it only lasts a few minutes. It’s just not feasible [for travellers].

Bug Off!

Pack these for protection

• ANTI-MALARIAL MEDICATION Also, speak to a doctor about bringing a self-treating kit for malaria with you on your trip.

• BED NET Most outdoor and camping-equipment stores carry bed nets. Consider getting nets that are treated with insecticide, which kills insects on contact and is effective for six months.

• REPELLENT WITH DEET Apply sunscreen first, wait 20 minutes, then apply DEET.

• INSECTICIDE An insecticide, such as permethrin, can be applied to clothing, bed nets, sleeping bags and tents (never apply to skin). Note: although permethrin is not currently sold in Canada, it can be imported for personal use.

• DOXYCYCLINE Ask a travel doctor about doxycycline, which can protect against malaria, leptospirosis and African tick-typhus.

Home Free? Not Quite

When you get home, get checked for these infections:

• Strongyloidiasis: caused by a parasite in soil that penetrates skin; travellers often don’t know they have it, but a blood test can detect it; is treatable if caught in time; fatality rate is very high

• Schistosomiasis: caused by parasitic larvae in freshwater snails that penetrate skin, become worms in body; worms produce eggs, which then cause infection; is treatable, rarely life-threatening; get tested if you’ve been in fresh water as is very prevalent

• Chagas’ disease: Trypanosoma cruzi is a parasite from kissing bugs that infest straw, mud and abode homes in Latin and South America and bite at night; bugs defecate the parasite, which causes infection when it enters the broken skin; travellers often don’t know they have an infection, as it can lay dormant for years, then become life-threatening when it damages heart muscle; is treatable with medication so early detection is advised

Note: This is a guideline only. Always get individualized advice from a doctor or travel health clinic before travelling. For more info, see Statement on Personal Protective Measures to Prevent Arthropod Bites, by CATMAT at the Public Health Agency of Canada, www.phac-aspc.gc.ca. Can be downloaded for free. Lawrence Foster is a Chase Producer for Mantracker on the Outdoor Life Network.

This entry was posted on Wednesday, July 23rd, 2008 at 1:29 pm and is filed under Health. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a comment, or trackback from your own site. Add to del.icio.us.