Adventure Doc

Glaxo experimental malaria vaccine works in babies
Wed 17 Oct 2007, 16:00 GMT
Reuters Africa

By Ben Hirschler

LONDON, Oct 17 (Reuters) – African babies — the group most at risk of dying from malaria — may be protected against the mosquito-borne disease by an experimental vaccine, researchers said on Wednesday.

The finding clears the way for final-stage testing of GlaxoSmithKine Plc’s shot and increases the chance that the world will have a usable vaccine within five years.

Malaria kills one person every 30 seconds, most of them young African children. Doctors believe a vaccine, given as part of routine infant immunisation, is the best hope in fighting the disease.

A clinical trial in Mozambique of 214 infants aged 10 to 18 weeks found the vaccine was safe and reduced new infections by 65 percent over a three-month period after treatment. Clinical illness was cut by 35 percent over six months.

Although such efficacy rates are not as good as for some childhood vaccinations, experts believe the huge burden of malaria means the new shot can still save millions of lives.

“This is a very major breakthrough,” lead investigator Dr Pedro Alonso of the University of Barcelona told reporters in a conference call.

“These tantalising and unprecedented results further strengthen the vision that a vaccine may contribute to the reduction of the intolerable burden of disease and death caused by malaria.”

ONE MILLION DEATHS A YEAR

Malaria, caused by a parasite carried by mosquitoes, kills more than 1 million people every year and makes 300 million seriously ill.

The latest findings, published online in the Lancet, are broadly in line with a 45 percent reduction in new infections reported in 2004 when Glaxo’s vaccine, known as Mosquirix or RTS,S/AS02, was given to children aged 1- to 4-years old.

Mosquirix will now go into a large-scale Phase III trial in the second half of 2008, involving 16,000 infants and young children in seven African countries.

If all goes well, the vaccine — which is the most advanced of a number in development — will be submitted for regulatory approval in 2011, suggesting it could be commercially available in 2012.

Glaxo has promised to sell Mosquirix at low prices in developing countries. The exact price will be negotiated with purchasers, who are likely to be multilateral groups who would cover the cost on behalf of countries where malaria is endemic.

Glaxo has spent $300 million developing Mosquirix and expects to spend another $50 million to $100 million in future.

But the trials programme is also being financed by the nonprofit PATH Malaria Vaccine Initiative, helped by a $107 million grant from the Bill & Melinda Gates Foundation.

Mosquirix — which is given in three doses — targets just one stage in the malaria parasite’s life cycle and its success has surprised some scientists, given the complexity of the disease.

The fact that it works suggests an improved vaccine, targeting multiple elements in the life cycle, might be even more effective.

http://africa.reuters.com/wire/news/usnL17759798.html
Link to Story

http://www.cdc.gov/malaria/risk_map/

CDC Malaria Risk Map

The CDC just released a new Malaria Risk Map that is interactive and pretty cool. The link is to the homepage and the just select to open the map, in a new window. Kinda like google earth with bugs!

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.

Traveler’s Diarrhea

This is, by far, the most common illness that affects people who travel. Traveler’s diarrhea can happen to anybody who leaves his or her city. This is because, when you travel, you encounter viruses and bacteria that are different to the ones that are in your hometown. Your body hasn’t built up immunity to this foreign stuff and it makes you a little sick. Sometimes it feels like it makes you a lot sick!

My main concern with diarrhea is whether there is blood or not. Most cases of diarrhea without blood do not need antibiotics or treatment other than a lot of fluids. When you have diarrhea, the water that your body stores is lost in the watery poop or vomit. It is essential that this be replaced! The normal amount of water your body needs per day (about 2-3 liters) must be replaced, in addition to what you are losing. Anybody that has had a bad case of diarrhea knows that this can be a lot of water. I advise replacing this lost water with water combined with a sports drink, such as Gatorade or Emergen-C. Make a glass of water only half-full and fill the rest with Gatorade. The Gatorade or other sports drink has potassium, salt and sugar (salt and potassium are important electrolytes). All these electrolytes are lost from your body, along with the water. Further, the sugar (glucose) in these sports drinks helps the water you drink get from your stomach and intestines into your blood stream quicker. This is where you need the water the most! If you are vomiting along with the diarrhea, still try to drink the mixture of water and sports drink. Even though it seems you are vomiting all of the drink back up, some is staying down and it is important to get even a little bit.

If you get into a tight spot and don’t have a sports drink/electrolyte drink to mix with your water, you can make your own. Two pinches of salt and two pinches of sugar added to a full glass of water will do the trick. Another piece of advice is to watch what you are eating for a few days. A bland diet of toast, soups, salads and fruit will help sooth an upset stomach and provide much needed water and electrolytes.

If you are seeing blood or running a fever, you should speak with your doctor. The presence of blood in the feces means that some bacteria is damaging the inside of the intestines and causing the lining of the intestinal wall to breakdown. This is a need for antibiotics. Of course if you have special circumstances such as being immunocompromised, pregnant or other chronic/long term illnesses and have any diarrhea, you should check with your doctor.

I am what you would call an “Adventurous Eater”. I eat at places I probably shouldn’t. I will try any new food. This is part of traveling to me. I also have frequent trouble with traveler’s diarrhea. This is a risk I know about and take. At the end of the day, the risk is up to the individual. Use your own common sense and judgment.

The majority of traveler’s diarrhea is caused by a bacterium called E. Coli. In fact, most cases of traveler’s diarrhea are from the E. Coli bacteria (up to 80%). There are a few types of E.Coli bacteria. There is an invasive form (EnteroInvasive E. Coli or EIEC), which can cause the bloody feces. There is a toxic form (EnteroToxic E. Coli or ETEC) that produces a toxin that does not usually cause bloody stools (poop). There are a few other types, but these are the main ones to know about.

Viruses are well known to cause diarrhea and some of the bad guys that do this are Rota Virus, Adeno Virus and Calici Virus (the famous Norwalk Virus is in this family). The problem with most viruses, in general, is that there is no real cure or treatment. The good thing is that, in most healthy people, viruses generally make you ill for a few days then go away on their own. Viruses that affect the GastroIntestinal (GI) System (stomach and intestines) do not usually cause bloody diarrhea. Rota Virus generally affects kids (6months to 3 years old) in developing countries. The Norwalk virus was made famous from several outbreaks that occurred on cruise ships. Viruses are very contagious and easily spread from person to person. The best way to stop the spread of GI viruses is to wash your hands, very often, with soap and water. Do this especially before you eat.

There are few other bad guys are capable of causing diarrhea in the traveler. One example is Giardia. This is a parasite that is most commonly seen in hikers and backpackers that drink from streams or lakes contaminated with the Protozoan (a type of microscopic organism). The way mountain lakes and streams get contaminated with Giardia is by people or animals defecating near the water. This is why you should always go at least 200 meters (2 football fields) away from the water source before “unpacking breakfast”. Giardia can be found worldwide, even in North America. To prevent this, hikers and backpackers should filter their water with a purifying system or use a bit of household bleach. I advise 2-4 drops of household bleach per liter of water (0.1 to 0.2 mL of bleach per liter). Boiling the water for at least 15 minutes works well, too. Iodine drops or tablets have been shown to be the worst method to use, as it is unreliable in killing the cystic form.

Cholera is a world famous bacterium. Cholera has caused several worldwide Pandemics as recently as 1994. Most of the problems were in developing nations. Cholera causes a severe form of watery diarrhea associated with vomiting. Cholera is common in developing nations, especially those in the tropics. Treatment for this nasty bacterial infection is aggressive re-hydration. Drink lots and lots of water! In healthy adults, Cholera generally lasts a few miserable days to a week and goes away on its own (if something goes away on its own, doctors call it “self-limiting”). In children, Cholera can be deadly due to the massive dehydration. Cholera kills many children in developing nations, just because they lose too much of their body’s water and can’t replace it! People get Cholera by eating or drinking water infected with the bacteria. This is why you should drink bottled water and eat at reputable restaurants with good hygiene, especially when traveling in tropical nations. Boling water is also effective, but often impractical in a hotel room. There are several vaccines available to prevent Cholera. They do not work very well and only provide protection against some types but not all. Further, they do not protect very well against the types they do cover either. I generally advise skipping a Cholera Vaccine and try to teach people what I have just said. Watch what you eat and drink. If you suspect that you have been exposed to Cholera, begin to replace the lost water from the vomiting and diarrhea with a water/electrolyte drink and contact your doctor.

Immodium? That seems to be a big question for travelers. Should I take it or not? There are some benefits and some negatives. Immodium is an anti-peristaltic drug that slows down the time it takes feces to move through your intestines. This means less diarrhea. Immodium (loperamide) decreases the number of loose stools by 80%. However, Immodium can trap invasive pathogens in the intestine, giving them more time to do damage to your body. The general rule is that if the diarrhea has blood in it, it is invasive. Invasive diarrhea means that the bacteria or pathogens are really damaging the intestinal wall. The last thing you want to do is trap them there, so the can do more damage. You want to pass them out of your body, as quickly as possible. However, if there is no blood in the stool and you are sure about this, immodium is great for slowing diarrhea down. This is especially important for business travelers and special circumstance trips, such as honeymoons. Please remember that early in an infection, the blood may be difficult to see, in the stool. A doctor can tell by performing a simple test. If there are any doubts, see a physician.

Another option for diarrheal control is bismuth subsalicylate (Pepto Bismol). Pepto-Bismol (bismuth subsalicylate) decreases the number of loose stools by 50%. Two tablets taken 4 times per day, Pepto is a good option for those looking for prophylaxis against traveler’s diarrhea. Pepto should be avoided by people with allergies to salicylates (aspirin) or those taking anticoagulants.

I am frequently asked about prophylactic antibiotics for travelers and I only advise their use in cases where travelers have a history of a prior medical condition such as HIV, inflammatory bowel disease or heart disease. Again, this is a decision that should be made between you and your personal travel doctor. Bactrim (TMP-SMX) or a flouroquinolone are generally the most common options.

Dengue Fever

Basics: Dengue is also known as “breakbone fever” after the muscular aches and myalgia it causes. An Arbovirus, transmitted by the bite of the Aedes mosquito, Dengue comes in 4 serotypes numbered 1-4. Found worldwide, this single stranded RNA virus is most closely associated with urban transmission. Infection may progress to Dengue Hemorrhagic Fever (DHF) and the risk of DHF increased with each subsequent infection. Typical symptoms include fever, severe muscle aches and fine petechial rash.

Location: Worldwide, more common in urban settings

Transmission/Incubation: transmitted by A. Aegypti in cities and A. Albopictus in jungles. Incubation is generally 5-10 days.

Prevention: Mosquitoe and vector control. See the Malaria section for information on this

Diagnosis: Serology/PCR

Treatment: Supportive Care including antipyretics, pain control and IV fluids.

Dengue fever is another virus spread by mosquito bites and usually found in the tropics. The nickname for Dengue fever is “break bone fever” due to the muscular and joint pains that come with the disease. Dengue fever usually features a skin rash, too. The disease usually lasts about one week. The concern with dengue fever is that the virus may cause “dengue hemmorhagic fever (DHF)”. This is a version of the virus that cause uncontrolled bleeding, usually from the GI tract (stomach and intestines), the nose or gums and easy bruising. Vomiting blood (hematemesis) and bloody (hematochezia) or dark black stools (melena) are some of the signs of GI bleeding.

People get dengue fever from the bite of the Aedes mosquito species. This species is unique, because it bites during the night and the day. Please see the section on malaria for tips on how to avoid being bitten by mosquitoes.

Dengue Fever has 4 main types: Dengue 1, Dengue 2, Dengue 3, and Dengue 4. The viruses are found in most tropical areas of the world. This includes Africa, Asia, South and Central America, the Caribbean, parts of Australia and the South Pacific. The concern with Dengue is not really the first time you get infected. Sure, you’ll be sick. The second time you get Dengue it is much worse and this is where the mortality rates (chances of dying) get higher. The third infection is even worse. If you are infected with one of the four types of Dengue, you are immune to that type, usually for life. However, you can still get infected by one of the other three. If DHF becomes sever, it can progress to Dengue Shock Syndrome and will require copious IV fluids with Saline or Ringers and may necessitate plasma or platelet transfusions.

There is no vaccine or medicine to take to prevent getting Dengue Fever. The best method is to avoid getting bitten. Long sleeves, long pants, bug spray with 30% DEET and some common sense.