Chloroquine, Azithromycin and arrhythmia?

EKGTravel medicine frequently uses medicines that are taken under special circumstances and for short periods of time, like a trip.  Many travelers carry an antidiarrheal antibiotic on their trip and a common choice is azithromycin.  This can potentially be a problem when they are also traveling in a malaria area and using chloroquine for prevention.  Two very commonly used medicines chloroquine (antimalarial) and azithromycin(macrolide antibiotic used for respiratory infections and diarrhea) both have wonderful safety profiles, individually.  However when taken together, there is discussion of the chance of a heart arrhythmia, specifically prolonging the QT interval.  In fact, my software I use for prescribing cites this as a combination to avoid. 

There are severalimportant articles that can be used to look at this problem and evaluate the risks.  One very good paper looks at medications that prolong this QT interval:

These authors list azithromycin as a “very improbable” medication, although other macrolides are listed as higher risk.  Chloroquine is listed as an “Unknown” medication, with respect to prolongation of QT interval.  This article was based on expert opinions.

This study looked directly at this problem, in animal models.  Their research showed no increase in arrhythmia risk. 

A wonderful article that is actually helping to look at using this drug combination to treat resistant forms of malaria.  More about this combination and treating malaria here.  Their study did show an increase in the QT interval in both groups of those who received chloroquine alone and those who received the combination of chloroquine and azithromycin.  This QT interval increase was maximum on day number three and returned to baseline by the end of the study.

Most of the information I am finding looks reassuring for safely using this combination, in healthy individuals.  Those with a history of arrhythmia should use this combination with caution and discuss this problem with their doctor, before they take these two medicines within a close amount of time.

Wilderness and Expedition Medicine Round-up: 3/24/09

Image: Inju

Image: Inju

With just a few more days remaining in a very tough month of work for me, I am excited to get back to writing more.  I thought a good way would be to re-cap the last few weeks of what I have been reading on the web:


Obviously, the recent high-profile case of head injury while skiing has generated a flurry of attention.  There are numerous articles and information to support wearing a helmet as an important method of injury prevention during outdoor sports.


  • Meningococcal disease in Nigeria continues to rise with over 5000 new cases reported since January 1st, 2009, and a fatality rate of just over 6%.  The sero-type of Nisseria implicated is group A and is preventable with a vaccination.
  • Malaria Atlas Project showcases their work on mapping locations of endemic Plasmodium Falciparum and a great article in PLoS (Public Library of Science) discusses the research
  • A bit older now, but MMWR (Morbidity and Mortality Weekly Report) from the CDC featured a very interesting article in the December 19, 2008 edition looking at Histoplasmosis in travelers from the US who participated in a church renovation in El Salvador


  • Guidelines for Field Triage of Injured Patients was published by the MMWR (CDC) in the January 23, 2009 edition and features a wealth of information building on their previously published work in 1999
  • The Gorgas Courses in Clinical Tropical Medicine have been sending out their “Case of the Week” and I have been enjoying them immensely.  Their tropical medicine program is one of the best in the world and anyone looking to further their clinical tropical medicine knowledge should look into this program.  I hope to attend one day, as well.


  • I am very happy for the team at for their Lonely Planet nomination and am always finding new and cool stuff on their site
  • is another site that is very well done, featuring loads of info on adventure travel including some great pictures
  • A new web and print magazine about adventure travel, sports and environmentalism over at is also a wonderful site

Help out Indie Travel Podcast win a deserved award!

I got an email from a friend with a request for help on his really awesome travel podcast website and I wanted to pass this along to anybody who might read this blog:

“The Lonely Planet travel blog awards is on, and our site, Indie Travel Podcast, is in the final five. Obviously, Lonely Planet is a huge name in travel and winning this would mean a lot to us.
We have until Friday to get 140+ votes for second place or 250+ votes for first place.
No registration, etc is needed. Just open this page, scroll down until you find “best podcast”, click the button beside “indie travel podcast” and click vote.

The competition is based on 50% public vote; 50% judges’ choice. Even in 3rd place we have a reasonable chance of winning. If we can make second, it would really help.
We need 140 votes in three days: can you help with one vote?
Would you consider emailing your friends/office too? Like I said, we need to find 140+ extra votes by Friday.
Thanks in advance,

Craig is the author of Travelling Europe —

Skype: mars-hill

Homepage –
Podcast –
Other – | |

Give him and his very cool/informative site a little love and vote!

Murray Valley Virus in Australia

Western AustraliaAs usual, Pro-Med mail has some of the best updates on disease spread.  The northern part of Western Australia has been subject of a warning from the Department of Health on increased transmission risk of the mosquito borne virus known as Murray Valley Encephalitis Virus.  Transmitted by the bite of an infected mosquito, the virus is known to damage the brain, spinal cord and meninges (encephalitis).

Heavy rains in the areas of Kimberly and Pilbara have contributed to an increase in mosquitoes and widespread biting.  The University of Western Australia Dept. of Epidemiology has also reported cases of Ross River and Bramah Forest virus in the area, as well.  There are no recommendations for travelers to avoid the area but mosquito bite preventionis highly suggested.  Warnings are specific for travelers and new comers to the area, who are most likely to be effected.  Children are also considered at high risk.  Those camping or sleeping near rivers or swamps in the area should have adequate preparation for mosquito bite prevention. 

Symptoms of the viruses include fever, headache, malaise/fatigue, stiff neck, nausea and dizziness.  If left untreated, the person may loose consciousness and suffer from seizures.  Death or permanent brain damage are possible.

Hookworms and why to wear your shoes!

Image: berbercarpetTropical climates are hot and sweaty.  A hot and sweaty environment, for me, usually means sandals or no shoes at all.  Aside from cuts and scrapes to delicate feet used to being protected by shoes, there are infections that can be acquired from going barefooted on your travels. 

Hookworm is a slang term used to describe a pair of intestinal parasites called Ancylostoma duodenale and Necator Americanus.  These parasites belong to the phylum Nematoda and are commonly found in the victim (or host) intestinal tract.  Evidence of the parasites can be found in literature as far back as ancient Egypt.  It was the ancient Egyptians who made a connection between anemia, a very common symptom, and the parasite. 

Hookworm under microscopy

Helminthitic infection of the intestines that frequently causes iron deficient anemia secondary to blood loss. Two species exist: Ancylostoma Duodenale and Necator Americanus. Acquired by direct contact with infected soil, usually walking barefoot. Characteristic “ground itch” is common at site of penetration. The life cycle is simple:  penetration of skin to blood stream, migration through the lungs, coughed up in phlegm and swallowed to stomach where they make their final home.  Eggs from the worms are passed into the soil through improper disposal of feces.  In the soil, the eggs mature into a form that can directly penetrate the human skin.

Tropical countries in areas with moist soil and poor hygiene in respect to fecal waste management. Both species are found in Africa, Asia, South Pacific and South America.  Americanus is most common in South/Central America. 

Transmission/ Incubation:
Transmitted via contact with infected soil containing 3rd stage larvae. Larvae directly penetrate skin. Most commonly acquired through human waste but some other species can transmit via cat/animal feces. Incubation can take weeks to months, as the parasites develop. Larger burdens of infection present quicker.

Hookworm egg under 400x microscope, in fecal smear

Hookworm egg under 400x microscope, in fecal smear

Use of shoes when walking, sanitary disposal of feces

Isolation of eggs in a fecal smear

Albendazole or Mebendazole. Studies done to show benefits of treatment based on number of eggs per gram of feces.

 Overall, this parasitic infection is a major health concern in developing nations causing anemia, pregnancy complications and malnourishment, espcially in growing children.  Fortunately, the infection typically responds well to medicine and elimination is possible provided there is adequate acces to healthcare.

For other trop med geeks (like me), you can visit the CDC DpDX website for some great pics on how to tell the difference between the two species.  Necator has cutting plates on the mouth while Ancylostoma has teeth, when viewed unuder a microscope.

Upcoming wilderness medicine events

Although I am busy with my day job, I still find a chance to seek out new education activities involving wilderness and travel medicine.  I wanted to share a few upcoming events:

Venom Week:  June 1-4, 2009 in New Mexico

Expedition Medicine Conference:  April 1-4, 2009 in San Diego

Wilderness Medical Society Summer Conference:  July 24-29, 2009 in Colorado

Lastly, the Gorgas Tropical Medicine program has been sending out some very cool “cases of the week” to remind me that I need to attend some more conferences and always keep learning!

Gorgas Tropical Medicine case of the week:


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