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Beaver fever symptoms, causes, treatment – Giardia

Beaver fever, most commonly known as Giardiasis, is a parasite infection. The cause is a microscopic parasite, “Giardia intestinalis.” 

Giardiasis (or beaver fever) is a major diarrheal infection that can be found throughout the world. The cause is a parasite, Giardia intestinalis, which is the most common intestinal parasite in the US.

Giardia represents a significant cause of disease in developing countries with poor sanitation. In developing countries, Giardia can be present in as much as 30% of the population. Giardiasis has a worldwide distribution, occurring in both temperate and tropical regions. Commonly, water-borne and food-borne outbreaks arise at any given time. 

In this article, I will review the essentials of giardiasis. Directly from a doctor, you’ll find the answers to all of the questions you can have about this disease. Frequently asked a question like: how is giardiasis transmitted? And, who is at risk of getting giardiasis? And many more simply explained.

Keep reading, so you can learn everything you need to know about this infection. 

What is Beaver fever? 

Beaver fever or giardiasis, like doctors call it, is a very common diarrheal disease. The cause is a microscopic parasite called Giardia intestinalis (previously known as G. lamblia or G. duodenalis.) Giardia can be within the intestine and cause no symptoms (asymptomatic colonization) or cause acute and/or chronic diarrhea.

This parasite damages the lining of the small intestine, causing diarrhea and malabsorption of food. It predominantly causes damage in the brush ends of the intestinal cells, responsible for absorption of water and nutrients.

Additionally, Giardia causes a swelling that increases the gut’s movements and fluid discharge to the inside of the intestine. Giardia infection is considered a zoonosis; this means it can be transmitted from infected animals to humans. Giardia parasite can be in the stools of dogs, cats, beavers, and primates.  

People get the infection by ingesting Giardia cysts, the infecting form of the parasite. The giardia infection can be transmitted person-to-person; it mostly happens to people with poor hygiene and sanitation. Also, the water-borne transmission is an important way to get Giardia, especially with the ingestion of unfiltered water. Finally, food-borne outbreaks are also possible, usually after secondary contamination by infected food handlers. 

Why is it called beaver fever? 

The medical name for this illness is giardiasis. However, it also receives the name of beaver fever. This is because of two reasons. The first one is that Giardia can be present in beavers’ feces, as in other animals. The second reason is because of an outbreak of giardiasis in Canada.

In that outbreak, a group of hikers at Banff National Park drank stream water contaminated with Giardia from beavers. Despite that this disease receives the name “Beaver fever”, Giardia can exist in other animals. Dogs, cats, and primate’s stools can transmit Giardia too.

Who is more likely to develop giardiasis?

Giardiasis can affect people of all ages. Among risk groups that can develop giardiasis mostly include contact with feces and contaminated waters due to poor sanitation. 

  • Children at daycare and their families or caregivers. 
  • Daycare workers.
  • Caregivers that assist other people on the toilet.
  • Travelers that go to developing countries in which giardiasis is so common.
  • Campers, backpackers, or hikers who drink untreated water.
  • Immunocompromised patients.
  • Anyone exposed to human feces during sexual contact.

These groups should take preventive measures more than groups with less risk of infection. Sanitizing water and washing your hands are the most effective ways to prevent getting and spreading giardiasis. 

What is the life cycle of giardiasis?

Giardia intestinalis has one of the most simplistic life cycles among parasites. It only has two forms: cysts and trophozoites. When doctors find any of these forms, both can serve for diagnosing the infection. However, the cysts are the ones that transmit the infection. This occurs because cysts are resistant and can live outside the body of the host. The cyst’s lifespan depends on the climate, humidity, and temperature, but it can live up to several weeks.

The infection begins when the person or host ingests the cysts in contaminated water, food, hands, or objects with the parasite on the surface. Then, in the small intestine, cysts release trophozoites. These trophozoites then reproduce and live in the small intestine.

Here, the trophozoites can live free or adhere to the intestinal wall, damaging the cells and causing GI symptoms. Once the trophozoites get to the colon, the encystation occurs. This way, the cysts are released to the outside, and the cycle continues. Animals can be infected with Giardia, too. However, it is not clear their importance as a reservoir for this parasite. 

How do people get Giardia or beaver fever?

Anything that comes in close contact with the feces of infected humans or animals can get contaminated with the parasite. The only way to get infected is by swallowing the parasite. It’s not possible to get infected through contact with blood or other body fluids.

Giardia can be transmitted by: 

  • Swallowing cysts you get from surfaces that contain feces of an infected person or animal. You can get giardiasis from contact with bathroom handles, diaper pails, toys, and changing tables. 
  • Drinking water or washing food with water from water sources contaminated with Giardia. 
  • Swallowing water while playing in the water or swimming in contaminated lakes, ponds, and rivers. 
  • Eating uncooked food with Giardia cysts, probably washed with contaminated waters. Also, not washing your hands before cooking or preparing food can contaminate it. 
  • Having contact with someone who is ill with giardiasis. 
  • Traveling to endemic areas of giardiasis (where there are high numbers of giardia cases) 

Even though animal feces can transmit giardia, the risk of getting it from your pets (dogs or cats) is small. This is because the giardia that infects pets is not the same type that infects humans. 

What are the symptoms of giardiasis or beaver fever?

Giardiasis can present itself in both acute and chronic manifestations. Symptoms of giardiasis can depend on various factors. The infection presentation depends on the number of parasite load, the virulence, and the host’s immune system. Symptoms habitually develop 1 to 3 weeks after the infection. The most common symptoms include: 

  • Diarrhea: It is the most common symptom, existing in around 90% of infected patients. Watery diarrhea can alternate with soft stool or even constipation. Chronic and sporadic diarrhea can be present for months after the acute manifestations.
  • Weakness.
  • Abdominal distention or bloating.
  • Flatulence.
  • Abdominal cramps
  • Fetid, greasy stools
  • Nausea and vomiting.

Some patients will experience an abrupt onset of symptoms. This includes diarrhea, painful cramps, flatus, and vomiting. These symptoms usually last for 3 to 4 days and then continue to a subacute syndrome, which comprises a milder form of the symptoms but that become a long-lasting problem. However, the majority of patients experience an insidious onset of symptoms that can become resistant or recurrent. 

Giardiasis can cause some upper gastrointestinal symptoms too. They can intensify after eating and often come with stool changes, although also possible in the absence of soft stools. These symptoms can include stomach cramping, early satiety, bloating, and acid indigestion or burning. 

In the case of chronic infection, the symptoms include chronic diarrhea, weakness, anorexia, and nausea. The sporadic chronic diarrhea may continue for months, causing weight loss in about two-thirds of patients. Adults can present food malabsorption syndrome, and children can suffer from an inability to grow. 

Giardia infection can cause some extraintestinal manifestations, but this is rare. Among these manifestations, we find hives, wheezing, cough, chest pain, joint pain, and other allergic manifestations. This is thought to be a result of host immune system activation. 

What are the complications of giardiasis or beaver fever?

Complications of giardiasis usually arise with the chronic form of this infection. Since the symptoms of chronic giardiasis are insidious, patients don’t always get medical help. Some of the most common complications are:

  • Diarrhea causes weight loss and dehydration: An infected person can lose up to 10-15 pounds. On the other side, severe dehydration due to diarrhea can cause you to end up in the ER. 
  • Malabsorption: This occurs mostly in adults. Giardia parasite damages the lining of the small intestine, making it unable to absorb nutrients. This can result in a deficiency of certain nutrients, like lactose and zinc. 
  • Failure to thrive and growth retardation in children result from poor absorption of nutrients needed to develop healthily.
  • Persistent gastrointestinal symptoms: Especially diarrhea, along with bloating, flatulence, and abdominal cramps. These symptoms can be recurrent and come and go every once in a while. 

What happens if giardiasis is left untreated?

Most of the time, giardiasis remains without symptoms or asymptomatic. This means that the patient probably would not receive any treatment. However, if you experience symptoms, you should get treatment as soon as you can. This is to prevent Giardia from damaging your intestine.

Sometimes, the symptoms may get better on their own. Some other times, the symptoms may persist over a few weeks, even with treatment. Persisting symptoms can result from injuries to the intestine that needs time to get better.

If you develop symptoms (you are a symptomatic patient), untreated giardia can result in complications like weight loss and dehydration. In the event of chronic infection, you can experience malabsorption and lactose intolerance (problems digesting dairy products). However, untreated giardiasis is not a life-threatening condition.

What can be mistaken for giardiasis or beaver fever?

Many conditions cause symptoms similar to giardiasis. Also, infections by intestinal parasites are mistaken between them since they share symptoms in common. The differential diagnosis of Giardia includes:

The illnesses above are all infectious diseases. They all cause acute diarrhea and can be transmitted in similar ways to Giardia. Other chronic conditions possess symptoms similar to giardiasis, such as:

  • Crohn disease.
  • Irritable bowel syndrome
  • Lactose intolerance.

These diseases are similar to giardiasis in the insidious onset of symptoms. They also share the characteristic of episodes of loose stools and symptoms like abdominal pain and bloating. 

How do you diagnose giardiasis or beaver fever?

If you believe you have giardiasis, you should go and see your doctor. They will perform the interrogatory and physical examination. Your doctors may ask questions about your symptoms and the characteristics of your poop.

The doctor may ask about what water you are consuming since giardia transmission is mostly by contaminated water. If your symptoms are compatible with giardia infection, your doctor will indicate that you take a stool sample.

Stool examination is the simplest method to diagnose giardiasis. This way, doctors identify cysts or giardia trophozoites and make the diagnosis. Ideally, the stool samples should be on three different occasions, on different days. This way, there is a greater chance of giardia cysts and trophozoites to appear in the samples.

There is also another test to diagnose giardia: stool antigen enzyme-linked immunosorbent assay (ELISA). Doctors utilize this test when the stool examination for giardia is negative, but they think Giardia is still the cause of the symptoms. It works by identifying some specific giardia proteins, making it very good to confirm or discard the infection.

In very specific cases, your doctor may indicate an endoscopy and biopsy. This is usually reserved for patients with both negative stool examination and ELISA but still have giardiasis symptoms. This way, doctors can identify giardia specimens in the intestine, as well as other parasites that cause similar symptoms. Also, a biopsy can help identify changes in the intestine cells that may be causing the symptoms.

What is the treatment for giardiasis or beaver fever? 

Nowadays, the standard treatment for giardiasis is antibiotics. The medication that doctors indicate for giardiasis is metronidazole. It has huge success rates in treating giardiasis; however, there has been a record of metronidazole resistant Giardia. This often happens in areas where there are too many Giardia cases and in travelers who go into these areas.

There is no standardized drug to treat this type of resistant Giardia. The giardiasis treatment is metronidazole 250mg per dose, three times a day for 5-7 days. Other drugs that are useful for treating giardiasis are tinidazole and nitazoxanide.

In the case of an asymptomatic infection, the patient should not get treatment. Treatment for asymptomatic patients is only indicated to prevent further household infection. Routine treatment for infected persons in areas of too many giardia cases is not recommended since reinfection from untreated water can easily occur.

Close contacts of an infected person should get examined for Giardiasis and get treatment if infected. In the case of reinfection (acquiring the infection again), a higher dose for a longer time usually results effectively. 

Keep in mind that infected patients need fluid and electrolyte supplementation because of diarrhea to prevent further complications. 

Do probiotics help with giardia?

Actually, yes. Probiotics are bacteria and yeasts that have benefits for your health. They play an important part, especially in your intestinal health. One of the many benefits that probiotics are thought to have is helping prevent Giardia.

Doctors are still studying it, but so far, the results seem promising. Many studies are showing that probiotics help prevent Giardia to adhere to the intestinal walls. This way, probiotics prevent intestinal infection. Also, this way, probiotics stop Giardia from causing damage to intestinal cells.

So, even if they don’t prevent the infection completely, they prevent further damage. In conclusion, it doesn’t hurt if you consume probiotic food. Not only to prevent Giardia but for your overall gut health. 

How hard is it to get rid of giardia or beaver fever?

It shouldn’t be hard to get rid of Giardia. If you follow the treatment that your doctor indicated, the infection should be gone immediately after. However, there are reports of resistant Giardia that doesn’t go away with treatment. Don’t worry; this usually happens in patients who live in regions with too many giardiasis cases. 

Another thing you should know is that, even after treatment, reinfection of giardia could happen. Receiving treatment for giardiasis won’t prevent reinfection, so you need to keep all the preventive measures you can. Drinking water from a reliable source and hand washing is the most important ones. 

Also, if you get treatment for giardiasis, all your other household members should get it too. This is to prevent reinfection among the members of the family. 

What is the prognosis of giardiasis or beaver fever? 

The prognosis of giardiasis is generally excellent. Most patients remain asymptomatic, and the infection is usually self-limited. This means that the infection and symptoms can resolve themselves without treatment.

The efficacy of treatment with an antibiotic is pretty good, and the resistance of the parasite is rare. The only exception is areas with too many cases and people who get infected in these areas. Overall, giardiasis does not usually cause death, except in cases of severe dehydration and malnourishment. 

Even with treatment, some patients may experience persistent symptoms. Symptoms like diarrhea and steatorrhea (greasy stools) are the ones that usually persist over time. Patients sometimes report bloating and abdominal pain after certain foods.

Chronic giardiasis may result in weight loss, food malabsorption, and growth retardation in children, as the most severe complications over time.

How can you prevent giardiasis?

Like any other parasite disease, you need to stop the transmission cycle to prevent it. There are many ways to prevent giardiasis. Thankfully, they are pretty simple to apply. 

  • Hand washing: Especially after possible contact with human or animal feces. This measure is important in caregivers of diapered children at daycares. 
  • Water treatment: Water sources should receive treatment with chlorination, sedimentation, and filtration methods. You can also purify water at home using filtration or boiling water for at least 5 minutes.
  • Avoid contaminated foods: Travelers to areas with too many giardia cases are advised to avoid foods that have been grown, washed, or prepared with contaminated water. 
  • Avoid recreational water venues: Like swimming pools. Even with chlorination, it is hard to keep a water venue Giardia free. Also, if you have giardiasis, you should avoid these venues until you remain symptom-free for a few weeks. 
  • Breastfeeding: Breastfeeding infants protects them from getting giardiasis. This occurs because breast milk has antibodies that protect the baby from intestinal infections. This method can be very useful, especially in developing countries with an increased risk of this disease. 

What foods should I avoid with giardia or beaver fever? 

There is no special diet for people with giardiasis. However, giardiasis may cause a deficit of the enzymes that digest lactose. This results in lactose intolerance for a big portion of the patients with Giardia. Acquired lactose intolerance (inability to digest dairy products) occurs in about 20-40% of patients. This can exacerbate symptoms like bloating, painful cramps, and diarrhea. Therefore, a lactose-free diet can help relieve or prevent these symptoms. 

If you are not experiencing lactose intolerance symptoms, then you can follow your regular diet. Keep in mind that, although not that common, contaminated food can be a way of transmission too. So, even if you don’t need to avoid foods, you should avoid eating food that hasn’t been properly sanitized. 

Does cold weather kill giardia?

Not really. In fact, cold weather can make Giardia live longer. The lifespan of Giardia cysts depends on the environment they are in. For example, in the soil, Giardia lives up to 49 days in cold weather and seven days in warm weather.

On the other side, in water, the cysts can survive from 1 to 3 months in cold weather. In warm weather, cysts in water only survive less than four days. Cysts’ lifespan also variates whether they are in dry or moist environments. In the case of dry, warm environments that receive direct sunlight, cysts only live for a few days. In a cool and moist environment, Giardia can live up to several weeks. 

You may ask yourself: if cold weather doesn’t kill Giardia, why do warm countries have a higher number of giardiasis cases? Well, because it doesn’t have to do with the weather. The higher number of cases in these countries is related to poor sanitation measures. Usually, developing countries don’t have enough sanitation measures to treat waters. So, there is a higher chance that people in these countries consume contaminated waters. 

Does giardia or beaver fever ever go away in humans?

Yes, Giardia can go away in humans. However, the only way to make Giardia go away is with proper antibiotic treatment. It is frequent for people without symptoms to have Giardia in their stool samples. These people don’t need to get antibiotic treatment. It would be best if you didn’t worry about this since Giardia can colonize the small intestine without causing damage sometimes.

Another thing that can happen is that you experience symptoms of giardiasis, and they disappear without treatment. This can take up to six weeks. Then, other chronic symptoms can appear, like the ones we mentioned before (malabsorption and lactose intolerance)

Basically, you shouldn’t worry about having Giardia unless it’s bothering you in some way. 

Do you have symptoms of giardiasis or beaver fever?

This is a Giardia Symptoms Checker. It gathers the most important signs, symptoms, and risk factors for this disease. Therefore, the tool will tell anybody who uses it the likelihood of their symptoms because of giardiasis (beaver fever). Using the tool is free and would only take a few minutes.

What do you think?

Written by Dr. Esteban Kosak

Doctor of Medicine - MD Recently Graduated from Medical School and inspired to aid the global population during this situation. I think that we shall no longer be waiting to see a doctor when we feel sick. Several times we feel disease searches in Google drive us to a rabbit hole and come out thinking that we may die of cancer or something very serious, given that symptoms may seem to fit a wide variety of illnesses. Since I recently graduated from medical school. I have all the medical information fresh in my mind. My thorough experience as an expert researcher allows me to very-well known the different diseases and conditions that affect human bodies. Empowered by the United Nations 17 Sustainable Development Goals (SGDs). I think that we all can provide a grain of sand to help humanity. That's why we created Symptoms.Care a place where you can come and screen your symptoms and find what different illnesses can be related to them. Armed with the right information you can instantly, discretely, secure and from the comfort of your home talk with a Doctor that can Evaluate your Symptoms and help you seek the right treatment.


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