Adventure Doc

The CDC released a statement a few days ago about some deaths associated with the yellow fever vaccine.

The immunization campaign was the country’s response in attempting to stop an epidemic, following their recent earthquake.

The Yellow Fever Vaccine is commonly given and well tolerated. There is an ongoing investigation with the CDC, WHO and PAHO to determine what the problem is. Theories include: a problem with the vaccine itself, a problem with the people who died (their bodies had a personal bad reaction to the vaccine) or a combination of the two.

The specific make of vaccine that is implicated is produced in Brazil and widely used in areas where YF is endemic. The Vaccine for YF, used in America, is from a different manufacturer. The batch of vaccines that is linked to the deaths has already been removed from use.

ProMed just released some news of a potential outbreak of Capillaria Philippinensis in the town of Zamboanga del Norte, Phillipines. I guess if there was going to be an outbreak of this intestinal parasite, it would be here.

81 people are already positive for the disease and 40 deaths have been recorded, including 9 children. Death from this parasite is generally through malnutrition and “starvation” or the host’s lungs filling with fluid. The parasites live in the intestines and “steal” all the nutrients from it’s host, causing malnutrition. Severe cases have such large amounts of parasites that the abdomen fills with fluid (ascites) and pleural transudates occur (lungs fill with fluid).

Once a person becomes infected, the parasite sheds its eggs in the feces of the host. The eggs look like trichuris eggs. If the feces contaminate water supply or lakes/rivers, the eggs hatch and begin to infect fish and water animals. Humans get infected when they eat the fish, raw or undercooked.

Capillariasis is an intestinal parasite that people get from eating raw or poorly cooked fish or crabs that are already infected. There are two types of this disease: Capillaria Philippinesis and Capillaria Hepatica. C. Philippinesis was first discovered in the 1960’s, in Luzon, Phillipines.

If you liked this stuff, you have to see more at AdventureDoc.org Helminth Page

The original article can be found here.

Mosquito Bite Prevention

700,000,000 people get a disease from a mosquito, each year. Of those diseases, 1 out of 17 people currently alive will die from the disease.

The species to know about are Aedes, Culex and Anopheles. These are the bad girls that carry diseases such as malaria, yellow fever, dengue fever and filariasis. I say “bad girls” because on the female mosquito bites mammals. The growth on new mosquitoes requires a blood meal. The males are content to only feed from flowers. Certain types of mosquitoes prefer animals, some prefer humans and some feed from both.

Attraction:

What attracts mosquitoes is not fully clear, yet. Mosquitoes do have developed senses of vision, thermal/heat sense and smell. They use all of their senses to find food. It is believed that the olfactory (smell) sense is the most important in finding victims.

During the daytime, dark colored clothing and movement help a female mosquito “lock on” to its target, at long range. As the mosquito nears her prey, the senses of smell and thermal sense take over. Carbon Dioxide and Lactic Acid are two of the most studied mosquito attractants. CO2 is mainly found in exhaled breaths and lactic acid can be found on the skin when muscles are being used, as in exercise. Lastly, skin temperature and skin moisture guide the mosquito to where they want to bite, on the body. It is widely assumed that certain species of mosquito prefer different body parts; hands, face, feet, etc. This could be due to the differences in local skin temperatures. Scented soaps, cologne, lotions and hair products can also attract mosquitoes.

As for personal preference, adults are preferred over children. Men are more commonly bitten than women and larger people get bit more than smaller people, possible due to their increased CO2 output. It also appears my wife is preferred over to me.

Chemical Repellents:

DEET (N,N Diethyl 3 Methylbenzamide) is the gold standard of insect repellent. It has been well studied for over 50 years and provides protection not only against mosquitoes but also flies, chiggers, ticks and fleas. The concentrations of DEET available range from 5% to 100% and the higher the concentration of DEET, the longer the time of protection. Concerns over long term exposure to high doses of DEET have led to the US Military to adopt a 35% slow release formula. The medical literature disagrees over a formula that accurately predicts number of hours of protection and DEET percentage. One study indicates a 4 hour protection with 50% DEET while another indicates 12.5% DEET protected for 6 hours. Products with 20-35% DEET generally provide adequate coverage for most instances. There are reports of skin irritation occurring more frequently with percentages greater than 35%. The Pediatricians advise nothing more than 10% DEET for children less than 12 years old. Use of DEET with sun-block lowers the efficacy of the sun-block. So, more frequent applications of sunscreen will be needed for adequate solar protection. The DEET spray is applied to the skin, first. Sunscreen is applied over the top of the DEET spray. I remember this because the DEET protects your blood and stays the closest. Sunscreen protects against the sun, which is further away. DEET is a well studied and commonly used chemical. High dose DEET has been shown to not be a neuro-toxin. There have been several cases of encephalopathy (brain swelling), mostly in children, with prolonged exposure and inappropriate use of DEET. DEET works by inhibiting signals from the mosquitoes’ antennae and making it hard for them to find you.

Avon Skin-So-Soft is known to be a mosquito repellant. Lab studies showed a 30-minute protection time against Aedes mosquitoes. Ideas as to why it is a repellent center around either fragrance of the cream or the chemicals it contains, benzophenone and diisopropyl adipate.

Permethrin is an insecticide that kills or stuns bugs. Permethrin is effective against mosquitoes, ticks, flies, chiggers and fleas. The chemical does not easily absorb into the skin. This is applied to clothing, bed nets or screens, as a spray.

Citronella is known as the “natural” mosquito repellent. Derived from a plant, Cymbopogon Nardus, the oil has a lemon-like scent. Studies have shown that burning citronella candles and/or incense decrease the number of insect bites, for those near to the candles or incense.

Timing is Everything

Most species of mosquitoes bite at dawn and dusk. Avoiding being outside will lessen your chances of bites. When you are sleeping at night, in open air environments, a bed net is definitely shown to decrease bites. Often, those staying in nicer hotel rooms, with climate control, do not need netting. Open windows mean a need for netting.

Learn more about mosquito carried diseases such as Malaria, Dengue Fever and Yellow Fever over at www.AdventureDoc.org

Caution should be used when traveling in Fiji, especially in the capital of Suva. According to the UK Foreign/Common Wealth Office, there are some reports of military checkpoints that are detaining any person deemed to be a threat to the newly formed interim government.

The “State of Emergency” has been lifted, since early October, but caution should be used due to potential political instability.

There is a predition of the worst meningitis outbreak in 10 years, coming to Africa.
Prediction of the worst meningitis outbreak in 10 years is not by loonies who think the sky is falling. Reasons for this potential outbreak are due to the rainy season ending early, in central Africa.

There is a region of Africa known as the “meningitis belt” that can be seen here on Adventure Doc Meningitis. There is also some information about meningitis and the vaccine there, too.

Travelers going to Africa or any other gathering of people who could be carrying meningitis, such as the Hajj, in December, need to be prepared.

The meningitis vaccine covers 4 types of Nisseria Meningitis (A, C, Y, W-135). These are the most common strains you will run into in Africa. Unfortunately there is a “B” type that is not covered by the vaccine. The “B” type happens to be one of the most common strains in North America and Europe.

The north-eastern area of Italy has recently been dealing with an outbreak of Chikungunya virus, for the last 2-3 months. The villages of Castiglione di Ravenna and Castiglione di Cervia in the province of Ravenna appear to be the center of the outbreak. There have been approximately 131 suspected cases, since July of 2007. More cases are under investigation, and testing results are still pending.

The center of the outbreak is believed to be traced back to a visitor, to the area, from Kerala, India. The mosquito Aedes albopictus is a new immigrant to Italy and is a know vector for this viral disease and mosquito “season” in the area is expected to run through mid-November. The chance of more transmissions in the area is likely.

Chikungunya Virus is a self-limiting (it goes away on its own) disease that is characterized by fevers, arthritis and a rash, mainly on the chest and back. The arthritis can persist for months, after the infection subsides and fevers generally last 10 days. The illness has been known to progress into hemorrhagic (bleeding) complications, similiar to Dengue Fever. More about hemorrhagic viruses can be found on the Adventure Doc page: Adventure Doc Hemorrhagic Viruses

To avoid this illness, protect yourself from mosquito bites! The diagnosis is made by serology from a blood sample.

You can view the Promed update here

Aircraft Cabin Air Recirculation and Symptoms of the Common Cold
http://jama.ama-assn.org/cgi/content/abstract/288/4/483

This was a pretty interesting article that looked at risks of catching a cold while traveling via airliner, due to recycled air.

The study looked at the main factor of recycled air in the cabins of commercial airliners and its risk factor for catching a cold. The article basically said there was no increased risk of catching a cold while flying, commercially.

I was convinced that I was getting sick from other people, in the cabin, due to recycled air. Hmmm, I guess it turns out I am just a hypochondriac with bad info!

Water disinfection

Knowledge of how to make water safe for human consumption or use is vital. There are basically three methods: heat, chemicals and filtration.

Heat:

Bacteria, viruses and most protozoan cysts (Giardia and E. Hystolytica) can easily be destroyed by heat. Time and temperature are inversely related. That means that the higher the temperature, the less time needed to disinfect the water.

I believe the best way to disinfect water is through boiling. Water is, generally, safe to drink after it reaches boiling point (100 degrees C). Just bringing the water to boiling temperature is killing pathogens. Just to make sure, boil the water for an additional minute. Giardia and E. Hystolytica have thermal death points at 60 degrees C, enteric viruses and bacteria die in seconds at 100 degrees C. The general rule is to boil water for a complete five minutes at sea level. There is a myth that you must boil water longer at higher altitudes. There is no need to significantly increase boiling time above 5 minutes, at altitude, because the thermal death points of most enteric pathogens is still within the 5 minute time window. Some negative sides of boiling water are the need for a heat source and fuel. Not everywhere is a good place for a fire and you may not always have cooking fuel. Heat is a one step process but doesn’t make the water look better if it is cloudy/murky.

Sterilization occurs after boiling for 10 minutes and kills spores, although spores are generally not know to cause GI problems. Pasteurization occurs when food or beverages are heated to 150 degrees Celsius for 30 minutes or 160 Celsius for 1-5 minutes.

Chemicals:

Halogens (chlorine and iodine) are very good disinfectants. The thing to remember about using chemical to treat water is the concentration of the chemical and the time needed disinfect the water. Concentration (the amount of the chemical in the water) is measured in milligrams per liter (mg/L) or PPM (parts per million).

Chlorine is used by most cities to purify drinking water for people’s houses. Chlorine kills Giardia, E. hystolytica, viruses and bacteria. Generally, using chlorine, I advise a 60 minute contact time. The amount of time required for 99.9% kill of pathogens depends on water pH and temperature. Household bleach (5% hypochlorite) is chloride. Adding 4 drops (0.2 mL) of bleach to one liter of water produces adequate concentration of 10 PPM and should be left to site for one hour.

Iodine is another halogen that is widely used to treat water. The goal of concentration of iodine to treat water is 3-4 mg/Liter or 4 PPM, given adequate contact time. Iodine generally requires less time than chlorine. Iodine, at 3-4 mg/L, generally makes water safe after 30 minutes of contact time. Remember that cold water needs a longer contact time. The iodine tablets are very easy to carry and small.

A few negatives about using chemical water treatment is the bad taste of the water. I advise mixing some electrolyte powder after the water has been treated. Also, people with unstable thyroid disease or those with iodine allergy should not use iodine. Its use in pregnancy should be avoided, longer than 1 week.

Filters:

Filtration is a very easy method to disinfect water. Most everybody knows somebody with a water filter. The thing to know about is pore size. This is the size, in diameter, of the particles than can pass through the filter.

Parasitic eggs and larvae are about 20 micro-meters
Giardia and E. Hystolytic are about 3-5 micro-meters
Bacteria are 0.4 micrometers
Filtration is ineffective against viruses because they are too small

Filters tend to clog, easily. This is especially true if you are filtering dirty/muddy water. Try to let the water settle for 30 minutes before filtering. This gives the larger particles time to drop to the bottom of the container via sedimentation. Filters can also be bulky to carry. There are some new filtration straws that work well, too.

Choosing which method to use is dependent on number of people in the group, time to devote to purifying water and equipment. Often times, a two-step process is best. Iodine with filtration is a very popular treatment that removes resistant cysts that iodine may not kill.

As for me, I prefer boiling, if I have the time and equipment. Actually, if possible, I try to filter and then boil. Filtration is my second favorite method, but takes up some extra room. Lastly, I carry iodine tablets for emergency. They are not my first choice, but I always have them nearby.

Food borne illnesses

People who travel are naturally adventurous. They are explorers and enjoy trying new things. This also includes eating new and different foods. To me, eating new and local foods when I travel is one of the most exciting and fun parts! There are a few illnesses that you can get from eating food, other than traveler’s diarrhea.

Scromboid is an allergic reaction people get from eating certain types of fish that are not prepared well. This involves a substance called Histamine. You may know this from allergy medicines that are anti-histamines. Histamines cause puffy, watery and itchy eyes, runny noses and swelling. Sever reactions can cause the throat to tighten so much that air cannot get into the lungs! When fish in the Scromboidea family (tuna, mackerel, skipjack and bonito) are killed and not quickly processed, the flesh can release large amounts of Histamine. When people eat this fish flesh they also eat large amounts of histamine. The symptoms include tingling and paresthesia (pins and needles feeling) around the mouth and arms. Symptoms usually resolve in 12 hours, on their own (self-limiting). For a bad reaction, anti-histamine medicine such as allergy pills work great.

Ciguatera poisoning is gotten from eating reef fish such as barracudas. Any reef fish that eats other fish may carry this risk, though. The symptoms of this illness begin with GI symptoms such as nausea and vomiting, usually within a day of eating the fish. Weakness in the legs is also common. Very severe cases may progress to coma and respiratory failure. Most patients recover in a few days to a week. The cause of this is a tiny organism called Gambierdiscus Toxicus that grow on the reefs. Smaller fish eat this stuff and when the larger, predatory, reef fish eat many of the smaller fish, the toxins accumulate in the larger fish. Humans eat the bigger fish and there is an accumulation of this toxin in the fish flesh. Mannitol (a diuretic medicine) can be lifesaving in severe cases. More about this can be read at this link:
Gambierdiscus Toxicus PDF Article

Paralytic Shellfish poisoning is just like them name sounds. You get it from eating mollusks (shellfish like bivalve mussels) and it causes paralysis. People generally suffer from paresthesia (pins and needles feeling) of the mouth and extremities (arms and legs) that lasts 1-2 days after the eating the shellfish. The symptoms usually begin with hours after ingestion. This is caused by Saxitoxins gathering in the shellfish. These Saxitoxins are associated with massive algae blooms know as “red tides”. When these shellfish are gathered by fisherman, the USA, Canada, Japan and Europe have mandatory screening for this toxin.

Puffer Fish Poisoning is a rare problem in Japan. There, Fugu is a special delicacy eaten in sushi bars. Fugu is a puffer fish that contains a poison called Tetrodotoxin. The poison can cause paralysis and death by respiratory failure, if not prepared by a highly trained chef. If you are going to try this…make sure you go to a reputable restaurant that has a lot of experience with this food. A good link to learn more about this is at:
Tokyo Cube Fugu Page

I guess you could call this post a “review” of the books I think are great to study from. As I run into some new books, I’ll put them up, too! Like anybody reads this, anyway. The two people, including my mom who read this, please tell me any books I might not know about!

TRAVEL:

Travel and Tropical Medicine Manual
By: Jong and McMullen
0-7216-4214-4

Control of Communicable Diseases Manual
By: American Public Health Association, Edited by D. Heymann
0-87553-035-4

WILDERNESS:

Field Guide to Wilderness Medicine
By: Auerbach, Donner, Weiss
0-323-01894-7

This list is in no way complete, but a good place to start. In fact, these are the books I often refer to, the most. Anybody want to mention any others?