Schistosomiasis: A disease among TRAVELERS [Parasitology]

By Sara Parvez

Schistosomiasis is a disease caused by penetration of parasitic worms in the skin. The parasite that penetrates the human skin is called cercaria which resides in a freshwater snail. Freshwater include pond, rivers, streams, or lakes. The infection cannot be acquired by contact with salt water of oceans and seas due to chlorination. A person can get infected by walking, swimming, or having any other contact with freshwater in disease endemic countries. Cercaria contaminates the water by swimming toward the human host and infecting it.  More than 200 million people are infected worldwide. Schistosomiasis is second only to malaria as the parasitic disease that cause most devastating. There are five types of Schistosomiasis distributed wouldwide. Out of five species three main ones infecting humans are S. haematobius, S. japonicum and S. mansoni which are found mainly in tropical and subtropical areas. Ever since the increase in tourism throughout Africa, sub-Saharan Africa, and South America there has been an increase in the number of schistosomiasis cases.

Complex Life cycle

1. Contact with the parasite in a freshwater.

2. Parasite enters the skin takes 3 days to reach blood capillaries.

3. Over the next 7 days the parasite migrates to the lungs, heart then the liver.

4. In liver they mature into adult worms and form male and female.

5. The average life span of the worm is 5 years, but can live up to 20 years.

6. The eggs release penetrates the bladder wall and goes in the urine. 

7. Eggs are eliminated in urine. In freshwater they can develop into mature blood flukes.

8. The eggs hatch and release miracidia which search for a snail host.

9. Between 4-6 weeks the infected snail release 3000 cercariae per day.

10. Cercariae penetrate human skin exposed in the water thus the life cycle begins again.

Areas where human schistosomiasis is found:

S. mansoni: Africa, South America and Caribbeans. An estimated 85% of the world’s cases of schistosomiasis are in Africa.

S. haematobium is distributed throughout Africa and sub-Saharan Africa including the great lakes. And areas of the Middle East

S. japonicum: Found in Indonesia and parts of China and Southeast Asia

S. mekongi: Found in Cambodia and Laos parts of Central and West Africa

Image displays the distribution of the cases of Schistosomiasis  due to Schistosoma haematobium, Schistosoma japonicum, and Schistosoma mekongi.

Image displays the distribution of the cases of Schistosoma mansoni and Schistosoma intercalatum.

 

Advice for Travelers

Travelers can avoid getting contact with the cercariae larvae by avoiding walking, swimming, or having any other contact with freshwater in disease endemic countries. Travelers should research on areas containing Schistosomasis epidemic before visiting them. If contact is unavoidable a person must take protective measures and undergo a checkup at a certified health center with knowledge in tropical medicine for recommendations. Always drink safe water by boiling water which can kill many bacteria and parasites. Take bath in hot water. Another way of avoiding contact with cercariae larvae in freshwater is by vigorously rubbing of the body with a towel. This brief method may or may not prevent the parasite form penetrating the skin, but it is effective most of the time. No vaccine is available. The drug of choice for all species of schistosomiasis is praziquantel.

References

Corachan M. Schistosomiasis and international travel. Clin Infect Dis. 2002 Aug 15;35(4):447–449.

Centers for Disease Control and Prevention. National Center for Health Statistics. Health Data Interactive. 9 July. 2012.

The Creation of Sea Monsters: Limb Malformation in Amphibians

By Christie Jackson

Introduction:

      Do you believe the Swamp Thing or the Loch Ness Monster is real? Probably not. But believe it or not, real aquatic monsters do exist. Neither Hollywood nor the media is responsible for the creation of these creatures -- the credit belongs to Ribeiroia ondatae, a species of parasitic flatworm (trematode) that, at 500-5,200 µm as an adult, is visible to the naked eye [1].

    R. ondatae is found mostly in North America where it has been observed in 46 states in the United States and in parts of Canada [2]. It can live practically anywhere containing freshwater including ponds, lakes, and drainage canals [7]. To complete its lifecycle, it must infect three hosts at different stages: planorbid snails, amphibians (specifically frogs, toads, and salamanders), and birds or mammals [1]. Although it causes particularly grotesque limb mutations in amphibians (particularly the addition of limbs, but also the deformation or absence of limbs) and infertility in the snails it inhabits, birds and mammals, the definitive hosts for R. ondatae, are not affected [1-4].

Amphibian malformations [3]

Lifecycle:

     R. ondatae eggs are released into the water by a definitive host, either a bird or a mammal. The eggs become a free-swimming, larval stage of the parasite, a miracidia. The miracidia then enters the first intermediate host, a planorbid snail. The snail may be from either the genus Planorbella or Biophalaria as both have shells resembling a ram’s horn [1,3]. The miracidia travel to the either the snail’s kidneys or the veins in the snail’s lungs to asexually reproduce becoming rediae. Often, R. ondatae will remove the snail’s reproductive organs during its own reproduction [3].

Ribeiroia lifecycle [2]

     Once expelled, the rediae become free-swimming cercariae. The cercariae locate the second intermediate host, a frog, a toad, or a salamander and attaches to the area that will become the host’s limbs. After attachment, the cercariae become metacercariae. As the host matures and goes through metamorphosis, the metacercariae signal the growth of additional, malformed limbs.

     Malformed individuals are often slower than normal individuals and are easily caught by predators. Once ingested by birds or mammals, R. ondatae mature into adults and sexually reproduce in the digestive tract of its host. The R. ondatae eggs are released into water with the definitive host’s feces, completing their lifecycle [1,3]
 

Ecology:

     The destruction of marine and freshwater ecosystems worldwide plays a major part in the parasite’s prevalence [4, 5]. Pollution often caused by agricultural run-off creates a build-up of nitrogen and phosphorus in aquatic habitat of the panorbid snails. This allows the snails to reproduce more rapidly creating more first intermediate hosts for R. ondatae to inhabit.

     The desire for the human population to expand creates a limited area for amphibians to reside. As they are being pushed into small geographical areas, the number of ponds or lakes decreases. Coupled with the rise in panorbid snails, the likelihood that an amphibian will become infected greatly increases. In some wetlands, greater than 50% of the amphibian population has been reported malformed [7].

     Prevention is key to help stop the decline of North American frogs, toads, and salamanders. Educating the public and encouraging activism to help clean up our water will not only positively impact amphibian population and health, but also the health of humans. Humans, wildlife, and the environment are all interconnected.

  

Host-parasite ecological continuum [5]

References:

[1] Johnson, P. T. J., D. R. Sutherland, J. M. Kinsella, and K. D. Lunde (2001). Review of the trematode genus Ribeiroia (Psilostomidae): ecology, life history and pathogenesis with special emphasis on the amphibian malformation problem.  Advances in Parasitology, 54: 192-253. 

[2] Johnson, P. T. J. and K. B. Lunde (2005). Parasite infection and limb malformations: A growing problem in amphibian conservation. Amphibian Declines: the Conservation Status of United States Species, 124-138.

[3] Johnson, P. T. J. and D. R. Sutherland (2003). Amphibian deformities and Ribeiroia infection: An emerging helminthiasis. Trends in Parasitology, 19: 332-335.

[4] Johnson, P. T. J. and J. M. Chase (2004). Parasites in the food web: linking amphibian malformations and aquatic eutrophication. Ecology Letters, 7: 521-526.

[5] Daszak, P., Cunningham, A. A., and A. D. Hyatt (2000). Emerging infectious diseases of wildlife – Threats to biodiversity and human health. Science, 287:443-449.

[6] Docampo R. (2002). Fifth Annual Conference on New and Re-Emerging Infectious Diseases. Emerging Infectious Diseases, 8(9): 1008-1010. 

[7] Johnson, P. T. J., K. B. Lunde, R. W. Haight, J. Bowerman, and A. R. Blaustein (2002). Parasite (Ribeiroia ondatrae) infection linked to amphibian malformations in the western US. Ecological Monographs 72(2): 151-168.

CHOLERA

By Heather Harper

                Cholera is one of the most widely spread deadly diseases worldwide.  Within the last year, there have been outbreaks in Haiti and Cuba with numerous deaths.   Cholera is caused from bacteria that causes severe diarrhea which leads to severe dehydration.  Dehydration, if not treated immediately can cause many other health problems such as death.  One of the signs and symptoms of cholera is watery, “rice” diarrhea.  It is called rice diarrhea because the diarrhea looks like it contains rice grains.

                The bacteria that causes cholera is found in water and food that has been contaminated.  You cannot get cholera from another person.  The way in which it is spread is by living in areas that do not have good sanitation or sewage treatment.   It is very important to wash your hands with soap and water. If you visit an area that has cholera or it’s an area with poor sanitation and sewage treatment, to avoid getting cholera, boil the water at least 1 minute.  Do not drink tap water, eat foods washed with tap water, or purchase fountain sodas.  Drink only bottled water and can sodas that are not open.  If you get sick, seek medical attention immediately.  Cholera can take anywhere from a few hours to 5 days to develop.  Most people have symptoms within 2-3 days.  The best treatment for cholera is to hydrate yourself with fluids and salts.  Here in the United States a good source of hydration would be sports drinks such as Gatorade or Powerade.  In other countries, you probably will need to see a doctor and receive intravenous fluids.  Once you have been hydrated, you will feel better in a couple of days and eliminate the risk of dying.  If you would like more information about cholera, check out www.cdc.gov.

               

Project Clear Water

by Justin B. Gossett

 

                Everyday stresses and simple illnesses kill countless people worldwide. Famine and disease and the C word people don’t like to talk about strikes daily and with unwavering lethality. Everyday thousands of people die from things out of their control, from a car wreck on the way home to a third miscarriage gone wrong. Water quality should not be one of those worries. For many of us that live here in the “modern” world we take for granit just how much something as simple as clean water means to people.

Clean water= Life

                Every year worldwide, waterborne diseases are the NUMBER ONE KILLER of children under 5 years of age, more people die from unsafe water than all forms of violence INCUDING WAR combined.

                The water we pour down the drain, the water we carelessly waste for frivolous uses, other people would fight for, even kill for, this water other people would die for. Clean safe water should not be just a commodity of the civilized world. Everyone deserves safe water, and that is what we aim to do here. Simply put this short blog is to raise awareness for how simple and inexpensive it actually is to utilize current water systems in these endemic countries to make their water safe.  To save lives.

                The good part is we are not limited in one expensive way of purifying the water; there are countless ways to go about making water clean and safe. From ceramic filters, to UV wands, to simply digging deep wells, just one per village can save them all, even a device as simple as the LifeStraw®. This device manufactured by Vestergraard Frandsen, has saved thousands upon thousands of lives and will continue to do so for years to come. The LifeStraw® is a simple device that each person can carry on their necks like a necklace, it’s simply a straw that filters the water as you drink. This was and remains a very inexpensive and life saving device that has been administered for years now with great success.

                There are some new comers to the game of cost effective water purification, one that stands out to me as a company who is truly trying to meet the needs of the people is that of Life Sack®. This ingenious water purification tool not only purifies water by a simple 5nm filter and the use of the sun to power its UV embedded shell, it also serves as a 20Kg bag to be used to ship grains or rice or whatever other staple food items of the region. Once the food has been removed, all they have to do is simply fill it with the contaminated water. And safe clean drinking water emerges. Simplicity is key in this battle.

                So as you can see there are many many ways to go about making clean safe drinking water attainable for EVERYONE in EVERY corner of the WORLD. With your help WE CAN MAKE THIS A REALITY. As there are many ways to go about purifying the water, there are just as many ways you can help. You can help with donations to ANY of these wonderful humanitarian companies that provide these life saving devices with little to even negative profit margins. You can help by actually going to these regions and passing out and teaching the locals how to properly utilize the filters. You can help by writing your governors and heads of state and ask them to please support and help fund these endeavors, you might even hint at how it would make them seem a step above their competition for future elections, good publicity is the best kind, and what better publicity than governor helps fund a project to save thousands. Even if the above are not your cup of tea, you can help by simply passing this along so others can see it. A simple repost of this on other blogs, other forums, even a simple Facebook© like will help spread the word of how we all can save countless people.

The saving of the entire world starts with but one person.

                 

               

Naegleria fowleri: Think before you leap

By Jeannie A. DeVane

Think before you leap into warm fresh water this summer! Lakes, rivers, hot springs and even soil can contain an ameba, which is a single celled organism. This organism is called Naegleria fowleri that infects humans. Naegleria fowleri is considered to be a thermophilic, meaning that it is warmth loving and occurs in the environment naturally and is worldwide.

Naegleria fowleri has three stages: The three stages of Naegleria fowleri consists of cysts, trophozoites, and flagellated forms in its life cycle.

Infection of Naegleria fowleri: Infection occurs when Naegleria fowleri enters the body through the nose and travels to the brain destroying brain tissue. The trophozoite stage is where the nasal mucosa is penetrated and migration to the brain occurs. Naegleria fowleri can cause a brain infection, and is almost always fatal. This usually occurs when someone goes swimming or diving, water gets sucked up the nose giving the ameba an advantage to make its way to the brain. Drinking contaminated water cannot lead to this infection and the infection does not spread through person to person contact. These infections are rare, but they do happen and as the environment warms up, lakes and rivers tend to warm causing this to be a problem due to the hot temperature air and low water levels.

Symptoms of Naegleria fowleri: Naegleria fowleri infection causes a fatal acute central nervous system disease known as PAM (primary amebic meningoencephalitis). PAM results in inflammation of the brain, inflammation of the lining of the brain, and inflammation of the spinal cord leading to destruction of brain tissue in the human body. Symptoms of Naegleria fowleri: Initial symptoms start one to seven days after infection including fever, headache, stiff neck, and nausea and vomiting. Later symptoms include loss of appetite, lack of attention to people and surroundings, loss of balance and bodily control, hallucinations, seizures, and coma. Death can result within 1 to 12 days and depends on the rate of the infection. 

Treatment of Naegleria fowleri: The treatment of Naegleria fowleri is still unclear for this infection. Laboratory drugs have been used to attempt to treat Naegleria fowleri, but their effectiveness is unknown due to the fact almost all infections tend to be fatal against Naegleria fowleri even when the patient is being treated. 

Diagnosis of Naegleria fowleri: Naegleria fowleri is diagnosed through the use of identifying the organisms, nucleic acid, and antigens in CSF, biopsy, and tissue specimens. Cysts are not seen in brain tissue.

Naegleria fowleri infection prevention: Avoid diving or jumping into freshwater when water temperatures are hot and the water levels are low. When diving or jumping into freshwater hold your nose closed. Use a nose plug or clip to prevent water from being forced up into the nasal passages. While you are swimming try to hold your head up above the water. Try not to dig or stir up the sediment while swimming in shallow freshwater.

References

1. Virginia Department of Health (VDH). Naegleria fowleri. Updated 08/18/2011 http://www.vdh.state.va.us/epidemiology/DEE/factsheets/pdf/Naegleria%20fowleri%20fact%20sheet.pdf

2. Centers for Disease Control and Prevention (CDC). http://www.cdc.gov/parasites/naegleria/biology.html

3. Shakoor S, Beg MA, Mahmood SF, Bandea R, Sriram R, Noman F, Ali F, Visvesvara GS, Zafar A. Primary amebic meningoencephalitis caused by Naegleria fowleri, Karachi, Pakistan. Emerg Infect Dis. 2011 Feb;17(2):258-61.

Onchocerca volvulus

By Mark R. Beatty

            How would you feel if you suffered from a disease that was neglected by the majority of the world, making it difficult to receive proper care?  The purpose of this is to educate you about a certain type of NTD (Neglected Tropical Disease) named Onchocerciasis, commonly called “River Blindness”.  There are approximately 37 million individuals that suffer from Onchocerciasis, all in Sub-Saharan Africa, Yemen, and isolated areas in Central and South America.  The diseases’ cause is the parasite Onchocerca volvulus, which is transmitted by the blackfly (Simulium damnosum).

            The parasite is transmitted near rivers and fast flowing streams, because this is where the blackflies live and breed.  The parasite itself is classified as a nematode (roundworm), and it inhabits the sub-cutaneous tissues of the human host.  Once the blackfly takes a blood-meal from an individual, the parasitic larvae enter the bite wound and begin to mature toward adulthood and will form nodules under the skin, sometimes called an onchocercoma.  Here the adult worms will live for the remainder of their lives, mating and releasing larvae into the infected individuals sub-cutaneous tissue so that they can migrate throughout the body.  The adult worms can survive within these nodules for up to 15 years and produce microfilariae (larvae) for up to 9 years.  These larvae can be found in the peripheral blood, urine, and sputum (mucus that is coughed up from the lower airways), but is most commonly found in the skin and lymphatics of connective tissue.  So, once another blackfly comes around to take a bloodmeal, it becomes infected with the parasitic larvae allowing it to develop further and become infective for another person.

            There are several symptoms to the disease caused by O. volvulus.  Most of the body’s responses to the parasite are due to the dead/dying larvae.  It can cause inflammation of the skin, along with itching and long-term damage to the person’s skin.  This can cause changes in the color of the skin which results in a “leopard skin” appearance, and can also cause thinning of the skin with loss of elastic tissue that gives the skin a “cigarette-paper” appearance.  “Hanging groin” is a possible symptom relating to losing the elasticity of the skin, the skin in the groin area will begin to sag severely.  The inflammation caused by larvae that die in the eye results initially in reversible lesions on the cornea that without treatment progress to permanent clouding of the cornea, resulting in blindness.  There can also be inflammation of the optic nerve causing vision loss, particularly peripheral vision, and eventual blindness.

            The most common method for diagnosing the  disease is to take about 5-6 shavings or biopsy of the skin in different areas to detect the larvae.  If the larvae are detectable, a PCR (Polymerase Chain Reaction) test may be administered. Infections in the eye can be diagnosed with a slit-lamp examination on the anterior part of the eye, where the larvae or lesions they cause are visible.  Ivermectin is the drug treatment for Onchocerciasis, it kills the larvae and prevents any of the damage from occurring.  This would need to be administered to a patient once every 6 months for the lifetime of the adult worm.

            This debilitating disease could be eradicated fairly easily with enough directed effort towards the matter.  It can simply be transmitted while an individual is simply fishing for food, or gathering water for a family but yet can have such serious effects on that person’s life.  Hopefully, with heightened awareness on the problem, we can begin to try and disrupt the transmission cycle of this parasite and save millions from losing their eyesight.

1.      The Filarial Genome Network. (2000) http://www.science.smith.edu/departments/Biology/SWILLIAM/fgn/pnb/oncvol.html

2.      University of Michigan Museum of Zoology:  Animal Diversity Web. (2001) http://animaldiversity.ummz.umich.edu/site/accounts/information/Onchocerca_volvulus.html

3.      CDC 24/7:  Saving Lives. Protecting People.  (2010)  http://www.cdc.gov/parasites/onchocerciasis/

4.      The Carter Center: Waging Peace. Fighting Disease. Building Hope. (2012)  http://www.cartercenter.org/health/river_blindness/index.html

Recreational fun leading to the runs or an untimely death?

by Chante Sanders

At the dawn of spring waterparks, pools, and amusement parks reopen leaving the lingering shadows of winter’s bareness behind. Some individuals are ecstatic about the warm weather and all of the many wonders that the great outdoors has to offer. As temperatures outside steadily rise, so does the number of individuals visiting local bodies of water. Hikers and swimmers alike are becoming more susceptible to the parasites that are in the environment.

The misconception that parasites only affect individuals in third world or developing countries can be the very reason that many people let their guards down allowing them to become a residence for parasitic protozoans, worms, and more.

 

When taking a swim in rivers, lakes and pools most don’t think of the possible infections that may await them. Although some situations are inevitable, sometimes taking simple precautions can change the likelihood of certain events occurring.

The parasite Giardia lamblia is a common cause of intestinal parasitic disease in the United States. Cases of Giardiasis between June and October doubled from 2006-2008. 

Symptoms of this parasite include:

• Diarrhea
• Gas
• Greasy stools 
•  Abdominal/ stomach cramps
• Dehydration (resulting from diarrhea)
• Nausea
• Vomiting. 

Taking a simple swim or inhaling water into the nose from contaminated rivers or lakes can lead to giardiasis.  Giardiasis can spread a number of ways but for the sake of the topic the focus will be on fresh water sources and recreational waters. This diarrheal disease is initiated by ingestion of contaminated water with the infective form of the parasite. The parasite then locates itself in the small intestine interfering with functions of the organ (absorption of nutrients, etc.).

 

Lets say that while on a hiking trip an individual decides to take a drink from the fresh water lake or river that is on the trail. If the water source is contaminated with the infective form of the parasite (called a cyst, more than ten of these would need to be ingested) the pathway for giardiasis infection has been initiated. When the parasite arrives at the small intestine of the individual the infective form starts to divide into another form of the parasite (called a trophozoite, one cyst makes two of this form of the parasite). This second form of the parasite inhibits the functional portions of the intestine responsible for fat and nutrient absorption by flattening. As the parasite moves further down the digestive tract the parasite returns to its infective state, the cyst. These cysts are then shed into the stool of the infected person. If the infected stool comes in contact with fresh water sources, food, and hands this increases the chances of the parasite infecting another individual or even our pets.

There are several ways to avoid this parasite including:

• Thoroughly washing hands after coming into contact with fecal matter that contains or suspected to contain the parasite. 
• If you are planning to hike or camp in an area where the fresh water source will be used for drinking water use a size appropriate filter (Giardia lamblia generally range in size from 1-10 microns) or avoid drinking the water.
• If you have small children that are infected with giardiasis NEVER take them to public water sources or allow them to use restrooms for public use.
• Avoid ingesting or inhaling water at public water sources

Another parasite, that is a much more scary problem in recreational freshwater or poorly maintained pools but not as prevalent in the United States (only 32 recorded cases between 2001-2010), Naegleria fowleri. Individuals infected with this parasite are not as lucky as those infected with Giradia lamblia, with out a timely diagnosis the parasite can render fatal results.

 

This parasite unlike Giardia does not infect its host by simply drinking contaminated water but by contaminated water entering the nose. Naegleria fowleri can be found in warm fresh waters. The parasite enters the human body through the nose and migrates to the brain where it causes Primary Amoebic Meningoencephalitis or PAM, inflammation around the brain/ spinal cord and destruction of the brain tissue. Naegleria fowleri is not transmitted from person to person, but by obtaining substantial amounts of water in the nose while water skiing, diving, underwater swimming or a significant amount of splashing in contaminated lakes or rivers.

 Symptoms of Naegleria fowleri include:

·         PAM

·         Headache

·         Fever

·         Stiff neck

·         Nausea

·         Vomiting

Later symptoms include:

·         Seizures

·         Hallucinations

·         Loss of balance

·         Confusion

·         Lack of attention to surroundings and people

 There are several ways to avoid this parasite:

• Avoid swimming in water with a temperature higher than 80^o F. (If the water does not feel cool upon entering, it is probably over 80^o F)
• Use nose plugs when water skiing or swimming in fresh water.

Even without the following parasites being a persistent problem in the United States knowledge is key. If planning on traveling to countries out side of the United States it is best to be acknowledgeable about the parasites that are causing disease in that area, if any. We cannot all ways control what gets into our bodies but if we become infected know the signs and symptoms can often time save further discomfort and /or lives.

References

Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 02 Nov. 2010. Web. 7 July 2012. <http://www.cdc.gov/parasites/giardia/biology.html>.

Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 22 Dec. 2011. Web. 7 July 2012. <http://www.cdc.gov/parasites/naegleria/faqs.html>.

Deq.state.ok.us/. N.p., June 2010. Web. 7 July 2012. <http://www.deq.state.ok.us/factsheets/water/pam.pdf>.