A BK virus (BKV) infection is a common viral infection that usually does not cause problems. The virus normally remains inactive in your body when your immune system is strong. However, in kidney transplant recipients, the use of immunosuppressive agents to prevent graft rejection is associated with BK virus reactivation, replication, and progressive infection. Managing BKV infection involves a multifaceted approach, including dietary considerations and lifestyle adjustments.
Understanding BK Virus
The BK virus (BKV) belongs to the Polyomaviridae family. Primary BKV infection typically occurs in the early years of life. It is believed that the overall IgG seroprevalence of BKV is approximately 82%. Direct person‐to‐person contact or by exposure to contaminated surfaces, foods, and water has been considered as the likely method of transmission. The virus persists within the kidney tissue and mostly does not cause any symptoms until it is reactivated.
BK Virus in Kidney Transplant Recipients
Kidney transplantation continues to be the treatment of choice for patients with end‐stage kidney disease due to the survival benefit in comparison with patients remaining on dialysis. However, in the modern immunosuppression era, BKV nephropathy (BKN) typically occurs in 1% to 10% of kidney transplant patients; 95% of cases are caused by BKV and 5% by human polyomavirus 2 (formerly JC virus or John Cunningham virus). Risk factors associated with BKV infection include Human Leucocyte Antigen (HLA) mismatch, cadaveric donation, degree of ischaemia‐reperfusion, female donor and male recipients, older age of recipients, ureteral stent insertion, acute rejection episodes, and immune‐suppressive therapy.
Prevention and General Recommendations
While there is no specific diet to prevent BKV infection, general health recommendations can help manage and prevent the spread. A BKV infection may go away on its own without treatment. Blood and urine tests will show if you are infected with the BK virus. If you take antirejection medicine, your healthcare provider may change or decrease your dose. Hyperhydration helps flush your bladder.
Hygiene Practices
- Wash Your Hands Often: Wash your hands several times each day. Wash after you use the bathroom, change a child's diaper, and before you prepare or eat food. Use soap and water every time. Wash the front and back of your hands, and in between your fingers. Use the fingers of one hand to scrub under the fingernails of the other hand. Wash for at least 20 seconds. Rinse with warm, running water for several seconds. Then dry your hands with a clean towel or paper towel. Use hand sanitizer that contains alcohol if soap and water are not available.
- Cover a Sneeze or Cough: Use a tissue that covers your mouth and nose. Throw the tissue away in a trash can right away. Use the bend of your arm if a tissue is not available.
- Clean Surfaces Often: Clean doorknobs, countertops, cell phones, and other surfaces that are touched often. Use a disinfecting wipe, a single-use sponge, or a cloth you can wash and reuse. Use disinfecting cleaners if you do not have wipes.
Vaccination
Ask about vaccines you may need. No vaccine is available for BKV, but vaccines can help protect your immune system. Ask your healthcare provider about the flu and pneumonia vaccines. All adults should get the flu (influenza) vaccine as soon as recommended each year, usually in September or October. The pneumonia vaccine is recommended for all adults aged 50 or older to prevent pneumococcal disease, such as pneumonia. Adults aged 19 to 49 years who are at high risk for pneumococcal disease should also receive the vaccine. You may need 1 dose or 2. COVID-19 vaccines are given to adults as a shot. At least 1 dose of an updated vaccine is recommended for all adults. COVID-19 vaccines are updated throughout the year. Adults 65 or older need a second dose of updated vaccine at least 4 months after the first dose.
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Post-Transplant Dietary Guidelines
Good nutrition is important after a transplant. After transplant, most patients will have more freedom with their diet, but healthy choices and food safety are important. It’s important that you work with your transplant team to create a healthy diet. Your dietitian will likely give you specific instructions and a meal plan. You may have fewer dietary restrictions than you did before your transplant. A healthy, balanced diet will help prevent high blood pressure, high blood sugar, excess weight gain and promote overall wellness and health. After a kidney transplant, plan to follow a diet low in salt and high in fiber.
A balanced diet includes a variety of fresh fruits and vegetables, lean meats, reduced-fat dairy products, whole grains, and plenty of water. It is important to keep your new kidney hydrated, so drink plenty of water and limit drinks with caffeine. Along with a healthy diet, you may need to avoid eating certain types of foods. Your healthcare team can help you understand which foods you should avoid - and why. The dietitian at your transplant center can help you find a diet that is right for you.
If you have diabetes, your diet after transplant should include three balanced meals to manage blood sugar. A balanced meal includes three different food groups with moderate amounts of carbohydrates and fat. Work with your doctor and dietitian to keep your diet and blood sugar in good control.
The Role of Vitamin D
Vitamin D supports immune function. Inadequate levels of 25(OH)D are common among KTRs, with only about 15% of KTRs having adequate 25(OH)D around the time of transplantation. Low 25(OH)D levels have been associated with increased post-transplant infection. Vitamin D deficiency (adjusted hazard ratio [aHR] compared to 25(OH)D sufficiency: 3.92; 95% CI: 1.66-9.23) and insufficiency (aHR: 2.22; 95% CI: 1.11-4.45) remained significantly associated with the incidence of BKPyVAN after adjustment for baseline characteristics.
Foods to Avoid After Kidney Transplant
Some foods and herbs can affect anti-rejection medicines, making them work more or less well than they should. This is called an “interaction” and can be unsafe for you and your new kidney. Some of the foods you should not eat after a kidney transplant include:
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- Grapefruit and grapefruit juice (please note that some citrus-flavored drinks have a grapefruit extract in them, so it is important to check ingredient lists)
- Pomegranate and pomegranate juice
- Seville Oranges (normal oranges are fine in moderation)
Many supplements and herbal products have interactions with anti-rejection medicines and may increase risks to your health and your new kidney. Please talk to your transplant doctor or pharmacist before starting any new supplements or herbal products. Some of the more popular herbal products that can have adverse interactions include:
- Vitamin C
- St. John’s Wort
- Herbal teas: green tea, chamomile, peppermint, dandelion
- Echinacea
- Ginseng
- Feverfew
Please talk to your dietitian, doctor or pharmacist if you have any questions about what foods, medications, or herbal supplements are safe to use after transplant.
High-Risk Foods List
It is recommended to avoid foods that are spoiled, moldy or past the “use by” date, as well as avoid the foods listed below. If you have any questions, talk to your healthcare team.
Meat, fish and poultry
- Raw or undercooked:
- Meat, poultry and fish
- Prawns or shrimp
- Crayfish
- Crab
- Squid
- Clams, oysters, and mussels
- Sushi
Dairy products
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Unpasteurized milk, cheese or yogurtEggs
Uncooked or undercooked eggs and any products containing them
Fruits and vegetables
- Grapefruit or grapefruit juice and pomegranate or pomegranate juice; especially if you are taking cyclosporine (Sandimmune) or tacrolimus (Prograf)
- Unwashed raw fruits and damaged fruits
- Unwashed raw vegetables and unwashed salads
- Unpasteurized juices or ciders
- Salad from salad bars or delicatessens
- Sprouts (like alfalfa or bean sprouts)
Food Safety
Another side effect of your anti-rejection medicines is that they weaken your body’s ability to fight infection. Taking these medicines increases your risk for getting sick from germs, such as bacteria. These bacteria can cause infections. Some bacterial infections can be picked up from food. You can help lower your chances of infection from food by:
- Handling foods safely, like washing your hands often, especially after touching raw chicken or eggs.
- Avoiding certain ‘high-risk’ foods because they are more likely to have bacteria that can cause an infection.
- Avoiding salad bars and food buffets when eating out.
- Reheating hot takeout food to a safe temperature if needed.
- Being thoughtful when eating food at big gatherings or picnics if it has been sitting out for a while.
Managing Weight After Transplant
Many people have a better appetite after they get a transplant, and they gain unwanted weight. If you lost a lot of weight on dialysis, this might be a good thing! But for many people, it can be hard to keep a healthy weight right after transplant. You can help take care of your weight by:
- Eating foods high in fiber, such as vegetables and fruits
- Choosing lean meats, such as chicken, turkey, and fish (not fried)
- Having nonfat dairy products, such as skim milk
- Drinking mostly water, with some unsweetened tea, coffee or milk
- Less fatty foods and foods high in simple sugar
- Planning ahead! Having daily or weekly menus makes it easier to choose healthy foods
Controlling your weight will lower your chance of having problems such as heart disease, diabetes, and high blood pressure, and generally help with keeping your new kidney working well. If you gain unwanted weight, you will need to exercise more and follow a lower calorie diet. Ask your doctor to refer you to a dietitian to plan lower calorie meals and snacks. Check with your doctor before exercise. Most often, exercising 3-4 times a week for 20-30 minutes each time or 5,000 - 10,000 steps every day can also help you maintain a healthy weight.
Sodium Intake
Most people still need to limit salt after they get a transplant, although it is different with each person. Transplant medicines, especially steroids, may cause your body to hold on to fluid, and salt makes this problem worse. Increased fluid in the body raises blood pressure. Controlling blood pressure is very important to your transplant. Your doctor will decide how much sodium is best for you. It is a good idea to limit foods high in salt, such as:
- Table salt
- Cured meats, such as ham, bacon, and sausage
- Lunch meats, such as bologna, salami, and hot dogs
- Pre-packaged frozen dinners
- Ramen noodles, boxed noodles, and potato and rice mixes
- Canned soups and pasta sauce
- Pickled foods, such as olives, pickles, and sauerkraut
- Snack foods, such as salted chips, nuts, pretzels, and popcorn
Monitoring for BK Virus Infection
After your transplant, your blood and/or urine will be checked on a regular schedule. BK viremia (BKPyV-DNAemia) and nephropathy (BKPyVAN) are significant causes of morbidity and mortality in kidney transplant recipients (KTRs).
Questions to Ask Your Healthcare Team
- What foods or supplements/vitamins should I be taking after transplant? What ones should I avoid?
- Are you concerned about me gaining weight after transplant? How will the team help me stay healthy?
- Do you have a dietician on the team who can help me after transplant?
- Based on my personal culture and the foods I like, what should I look out for? Is there anything I should adjust or think about?
Diagnostic Procedures
Renal biopsy with characteristic viral cytopathic changes in tubular epithelial cells and Simian Virus 40 (SV‐40) immunohistochemistry is considered the gold standard for BKN diagnosis. BKV detection by real‐time polymerase chain reaction (PCR) of plasma with a threshold of 4.1 log 10 copies/mL has 100% sensitivity, ˜90% specificity, 50% positive‐predictive value and negative predictive value of 100% in BKN diagnosis. On the other hand, BKV detection by PCR of urine with a threshold of 2.5E+07 copies/mL has 100% sensitivity, 92% specificity, 31% positive predictive value, and 100% negative predictive value. Furthermore, the presence of decoy cells in urine sample has 25% sensitivity and 84% specificity.
Treatment Strategies
The current standard of care recommends monthly BKV quantitative plasma nucleic acid testing for the first three to six months post‐transplantation; the frequency of testing can be reduced to three monthly until the first post‐transplant year. Management of BKV infection has been complicated. Most of the literature reiterates the importance of immune‐suppression reduction.
The mainstay of therapy for BKV infection is to improve BKV‐specific immunity by reducing the intensity of maintenance immunosuppression or to administer medication with antiviral effect. The usual strategies in treating BKN are reducing the dose of calcineurin inhibitors (CNI) or MMF), cessation of azathioprine (AZA) or MMF, concomitant reduction of both CNI and anti‐metabolite, switching of CNI to mammalian target of rapamycin (mTOR) inhibitor, and switching of TAC to cyclosporine. Drugs with anti‐polyoma effects such as cidofovir, leflunomide, FK778, and fluoroquinolones have also been used to enhance viral clearance and/or suppression.
Symptoms of BK Virus Infection
Since BK virus can “wake up,” it is important to watch for signs of infection. Symptoms may include:
- Changes in vision, like blurred vision
- Changes in the color of your urine (urine that is brown or red in color)
- Pain when you urinate
- Difficulty urinating
- Needing to urinate more than is normal for you
- A cough, cold, or trouble breathing
- Fever, muscle pain, or weakness
- Seizures
Having any of these symptoms could be a sign of infection. It is important to tell your healthcare provider if you notice any signs of infection.
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