What is wisteria disease?

Department of Health

Listeriosis (Listeria infection)

Reviewed: September 2017

What is listeriosis?

Listeriosis is an infection caused by the bacteria Listeria monocytogenes. People become infected by eating foods contaminated with the bacteria. Listeria may infect many different sites in the body, such as the brain, spinal cord membranes, or the bloodstream.

Who gets listeriosis?

Anyone can get the disease, but those at highest risk for getting it are pregnant women, the elderly, people with weakened immune systems (for example, people with cancer, HIV/AIDS, or a transplant), and people with chronic liver or kidney disease, diabetes, or alcoholism. Healthy adults and children occasionally are infected with Listeria, but they rarely become seriously ill. Although most cases occur as single cases, food-borne outbreaks (when two or more people become ill from the same source) do occur.

How is listeriosis spread?

Listeria bacteria can be found in water and soil. Infected animals, even if they are not sick, may carry the bacteria, spread it, and contaminate foods. Listeria can be spread to people by several different methods. Eating food contaminated with the bacteria, such as through raw (unpasteurized) milk or contaminated vegetables, is often a source for cases. The bacteria may be passed from mother to fetus during pregnancy or directly to the newborn at the time of birth.

What are the symptoms of listeriosis?

Because listeriosis can affect many different parts of the body, the symptoms vary from mild to severe. Listeria can cause fever and diarrhea (loose stool/poop) similar toother foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms vary in people with invasive listeriosis, meaning the bacteria has spread beyond the gut.

  • Pregnant women: Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
  • People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.

How is this disease diagnosed?

Specific laboratory tests are the only way to diagnose this disease. A blood, spinal fluid, or amniotic fluid/placenta test that looks for the bacteria will be able to show if the disease is present.

What is the treatment forlisteriosis?

Listeriosis is treated with antibiotics. Ampicillin, either alone or in combination with other antibiotics, is often used.

Does past infection with listeriosis make a person immune?

Past infection does not appear to make a person immune. People can be reinfected if exposed to the Listeria bacteria again.

What can be done to prevent the spread of this disease?

Since the bacteria is widespread in nature, basic sanitary measures such as using only pasteurized dairy products, eating cooked meats, washing produce, and washing hands, kitchen work surfaces, and utensils with soap and water immediately after they have been in contact with raw meat or poultry offers the best protection.

In addition, the following recommendations are for persons at high risk, such as pregnant women and people with weakened immune systems (for example people with cancer, HIV/AIDS, or a transplant):

  • Do not eat hot dogs, lunchmeats (or deli meats), unless they are reheated until steaming hot.
  • Avoid getting fluid from hot dog and lunch meat packages on other foods, utensils, and food preparation surfaces, and wash hands with soap and water after handling hot dogs and lunch meats.
  • Do not eat soft cheeses such as feta, Brie, and Camembert, blue-veined cheeses, or Mexican-style cheeses such as queso blanco, queso fresco, and Panela, unless they have labels that clearly state they are made from pasteurized milk.
  • Be aware that Hispanic-style cheeses made from pasteurized milk, such as queso fresco, have caused Listeria infections, most likely because they were contaminated during cheese-making.
  • Do not eat refrigerated pâtés or meat spreads. Canned or shelf-stable pâtés and meat spreads may be eaten.
  • Do not eat refrigerated smoked seafood, unless it is contained in a cooked dish, such as a casserole. Refrigerated smoked seafood, such as salmon, trout, whitefish, cod, tuna or mackerel, is most often labeled as “nova-style,” “lox,” “kippered,” “smoked,” or “jerky.” The fish is found in the refrigerator section or sold at deli counters of grocery stores and delicatessens. Canned or shelf-stable smoked seafood may be eaten.
  • Do not eat raw or lightly cooked sprouts of any kind (including alfalfa, clover, radish, and mung bean sprouts).
  • Cook sprouts thoroughly to reduce your risk for getting sick. Thorough cooking kills the harmful bacteria.
  • When you’re eating out, ask that raw sprouts not be added to your food. If you buy a ready-made sandwich, salad, or Asian food, check to make sure it doesn’t contain raw sprouts.

Listeria monocytogenes (Listeria) is a foodborne disease-causing bacteria; the disease is called listeriosis. Listeria can invade the body through a normal and intact gastrointestinal tract. Once in the body, Listeria can travel through the blood stream but the bacteria are often found inside cells. Listeria also produces toxins that damage cells. Listeria invades and grows best in the central nervous system among immune compromised persons, causing meningitis and/or encephalitis (brain infection). In pregnant women, the fetus can become infected, leading to spontaneous abortion, stillbirths, or sepsis (blood infection) in infancy.

Approximately 2,500 cases of listeriosis are estimated to occur in the U.S. each year. About 200 in every 1000 cases result in death. Certain groups of individuals are at greater risk for listeriosis, including pregnant women (and their unborn children) and immunocompromised persons. Among infants, listeriosis occurs when the infection is transmitted from the mother, either through the placenta or during the birthing process. These host factors, along with the amount of bacteria ingested and the virulence of the strain, determine the risk of disease. Human cases of listeriosis are, for the most part, sporadic and treatable. Nonetheless, Listeria remains an important threat to public health, especially among those most susceptible to this disease.

The affected states so far include Texas, South Carolina, Florida, Pennsylvania, and Maine. The CDC has created a live map of recorded cases, which you can check for updates.

Note: The alert pertains only to the above product, which is sold in stores, and it does not include eggs from other brands or eggs sold directly to consumers by Almark Foods.

Consumers are being advised to throw this product away if they have it in their homes, while food retailers are being told not to sell it. The eggs have not actually been recalled.

Pregnant women and older people are generally at a higher risk for listeria infection (or listeriosis), as are people with immune system problems. The scary thing is, symptoms often don’t begin to show up until about one to four weeks after you’ve eaten contaminated food, and it can sometimes take months. In other cases, you might feel them right away, the CDC says.

Here are the symptoms the CDC says to watch out for:

  • Pregnant women: “Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.”
  • Everyone else: “Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.”

Listeriosis is treated with antibiotics, so see a healthcare professional if you think you might be infected. You can check out the full safety alert here.

Growing Wisteria

A gardener’s guide to planting & caring for a wisteria vine By Anne Balogh


Brimming with clusters of fragrant flowers in spring, the showstopping wisteria vine is loved by many gardeners despite its assertive reputation. An extremely vigorous grower, this perennial can get out of hand easily unless carefully restrained. Here are some tips for cultivating all wisteria has to offer while taming its aggressive growth habits. Too see other options, check out our list of flowering vines.

  • Wisteria Basics
  • Planting Wisteria
  • Pruning Techniques

Photo by: 2204574 / .com.



On average, wisterias will grow to be 10 to 30 feet.


Full sun (at least six hours per day).

Bloom time:

Most wisteria vines begin blooming in spring and may carry on into summer.

Types of wisteria:

When it comes to wisteria there are two types: Asian and American. Asian wisterias are popular due to their impressive flowers, but are aggressive growers. American wisterias are tamer and still have gorgeous flowers. Compare the most common types of wisteria.

Flower color:

Wisteria brings to mind iconic purple flowers, but there are a variety of other colors including shades of white, pink, and blue. There are no yellow wisteria flowers, if you think you’ve seen one it was likely a golden chain tree (Laburnum).


Wisterias are deciduous, which means they drop their leaves in the fall in response to cold temperatures. However, there is another vine commonly called evergreen wisteria (Millettia reticulata), that sometimes causes confusion.

Avoid growing aggressive wisterias near your house, because they can wreak havoc and have even been reported to destroy homes.

Plant wisterias in full sun or partial shade, but make sure the vines receive at least six hours of direct sun daily to encourage good flower development. Also choose a sheltered planting location if you live in a colder climate, since the flower buds can be damaged by a hard spring frost.

Dig a planting hole the same depth and twice the diameter of the plant’s root ball and set the plant level with the soil line. Space your plants at least 10 to 15 feet apart along the support system, because the vines will fill in quickly.

Once planted, wisterias require little pampering to encourage robust growth. During the first year, water regularly until the roots establish.

Wisterias may be slow to emerge from dormancy right after planting and may not leaf out until early summer. The following spring, they will leaf out at the normal time, but don’t be surprised if they don’t produce flowers. Wisterias are slow to mature and may not begin flowering until three to five years after planting.

Wisterias are rapid growers and can shoot up 10 feet or more in a single growing season. That’s great if you want to quickly cover a fence or pergola, but you don’t want the vines to overrun your garden. Regular pruning (once in summer and again in winter) not only keeps wisteria in bounds, it will also promote more vigorous flowering by establishing a framework of horizontal branches and inducing the formation of spurs at controlled intervals.

In July or August, or approximately two months after the plant flowers, cut back the current year’s growth to five or six leaves to remove unruly shoots and create short branches that will bear next year’s blooms. Additional summer pruning is often required. When the plant is dormant in January or February, prune again by cutting back to two or three buds on last year’s growth.

With newly planted wisteria, the first few years of growth are important to establishing the desired framework for the plant’s development. As soon as your wisteria takes off, begin tying selected lateral shoots to its support system and prune back unwanted growth. With older plants, a hard pruning may be needed to encourage new branch development. Do this by cutting back older branches to the main central stem. New side branches will soon replace the gaps and can be tied back into the support system.

Visit the Royal Horticultural Society to see a video demonstrating the proper pruning techniques for wisteria vines.


Wisteria requires a sturdy support structure, such as this well-built pergola.

With its climbing agility and fast growth habits, wisteria can completely transform a garden in just a few years, becoming a breathtaking shade cover, privacy screen, or focal point. Wisteria has the greatest impact when trained to grow on pergolas, arbors, and other strong overhanging supports so the long flower clusters can hang freely, creating a stunning floral canopy. In Japan, wisteria is even trained onto massive trellises to form blooming tunnels in spring. You can also train wisteria onto wires mounted on fences or stone walls or drape them over garden benches or arched entryways.

Although you may be tempted to let wisteria twine around the trunk of a tree, its vice-like grip will eventually strangle it. To achieve a similar effect, you can train wisteria as a single-trunk, free-standing tree by staking the thick woody stem of the plant to a sturdy post or 4-by-4 embedded securely in the ground. As the plant grows, remove all unwanted growth along the trunk, allowing only the top to grow. Using the same techniques on a smaller scale, wisteria can be grown in large pots or as a bonsai tree.

Whatever trellising method you use, make sure the system is sturdy. Wisterias will readily topple weak wooden trellises, so use durable materials such as heavy metal pipe set in concrete or pressure-treated or rot-resistant wood beams. Also avoid growing the vines alongside your house, because they can creep under siding and wrap around gutters.

Keep in mind that once wisteria becomes well-established, it can be very difficult if not impossible to move later. Choose your planting location and design intent carefully, because you may not be able to change your mind later.


Be patient, a newly planted wisteria may take several years to mature before it begins flowering.

Gardeners are often devastated when their wisteria fails to bloom the first season after planting. With young plants, be patient. Wisteria takes several years to mature and become established before it begins flowering with gusto. However, a lack of flowering can also be attributed to other factors, such as too much fertilizer, improper pruning, injury to the flower buds by frost exposure, or too much shade. Here are some tips from Toronto Master Gardeners for guaranteeing a profusion of blooms:

  • Avoid buying wisteria planted from seed. Seed-grown plants remain in a juvenile state for an extended period and can take up to 15 years to bloom. Instead, choose varieties that are grafted or propagated from cuttings from a reliable bloomer.
  • To eliminate the risk of frost damage to flower buds, grow American wisteria or Kentucky wisteria. These plants form buds on the current season’s growth.
  • Don’t overwater or fertilize established vines. Wisteria needs to undergo a bit of stress to force the development of flower buds. Too much water or the application of high-nitrogen fertilizers will encourage leaf production at the expense of flowering.
  • Wisteria planted in full sun will bloom more reliably than plants located in part shade. Make sure the upper part of the plant receives at least six hours of daily sun exposure.


Here are some of the most popular wisteria cultivars:

Swipe to view slides

Photo by: Müller/ McPhoto / Alamy Stock Photo.

Wisteria floribunda ‘Rosea’

Soft pink 13- to 16-inch flower clusters tinged with lavender. Grows more slowly than other cultivars (2 to 3 feet per year), making it a good choice for smaller gardens.

Zones: 5-9

Photo by: Garden World Images Ltd / Alamy Stock Photo.

Wisteria floribunda ‘Snow Showers’

Pure white, pea-like flowers give the impression of snow falling in springtime. Very fragrant.

Zones: 5-9

Photo by: nnattalli / .

Wisteria floribunda ‘Longissima Alba’

Very fragrant white wisteria with dense flower clusters up to 20 inches long.

Zones: 4-9

Photo by: Tim Gainey / Alamy Stock Photo.

Wisteria floribunda ‘Royal Purple’

Very fragrant white wisteria with dense flower clusters up to 20 inches long.

Zones: 4-9

Photo by: Garden World Images Ltd / Alamy Stock Photo.

Wisteria floribunda ‘Violacea Plena’

Showy blue-violet double flowers that fade to pale lavender.

Zones: 5-9

Photo by: InfoFlowersPlants / .

Wisteria sinensis ‘Alba’

Short clusters of fragrant, pure white, pea-like flowers.

Zones: 5-8

Photo by: Wiert Nieuman / Alamy Stock Photo.

Wisteria sinensis ‘Prolific’

Noted for its prolific clusters of lilac-blue flowers. Typically begins blooming at an earlier age than other cultivars.

Zones: 5-8

Photo by: Garden World Images Ltd / Alamy Stock Photo.

Wisteria frutescens ‘Amethyst Falls’

Blooms at an early age, often its first season, with lightly fragrant lilac-blue flowers. Blooms also arrive about two weeks later than other varieties, so the buds are rarely affected by a late frost.

Zones: 5-9

Photo by: Carl Boro / Millette Photomedia.

Wisteria frutescens ‘Longwood Purple’

This American wisteria flowers later than Asian varieties, but can repeat bloom through September. Offers a remarkable display of grape-like flower clusters.

Zones: 5-9

Photo by: Jennifer Martin-Atkins / Millette Photomedia.

Wisteria macrostachya ‘Aunt Dee’

Abundant 8- to 12-inch-long clusters of fragrant lilac-blue flowers on new growth. Blooms at an early age.

Zones: 4-9

Photo by: blickwinkel / Alamy Stock Photo.

Wisteria macrostachya ‘Blue Moon’

Produces foot-long clusters of lavender-blue flowers in spring, with repeat blooming throughout the growing season once established.

Zones: 3-9

Photo by: Paul S Drobot / Millette Photomedia.

Wisteria macrostachya ‘Clara Mack’

A pure white flowering form of Kentucky wisteria with dark green foliage.

Zones: 3-9

Not pictured:

Wisteria floribunda ‘Lawrence’
Pale violet-blue flowers. The 12- to-18-inch clusters are loaded with as many as 160 blooms, more than all other Japanese wisteria.
Zones: 5-9

Wisteria frutescens ‘Nivea’
Densely packed white flower clusters only 6 inches long, creating a pinecone-like shape.
Zones: 5-9


American Meadows
Brushwood Nursery
Digging Dog Nursery
Fast Growing Trees Nursery
Nature Hills Nursery
Spring Hill Nurseries
Thompson & Morgan
Wayside Gardens
Wilson Bros Gardens


How large can wisteria get?

Wisteria vines can grow to epic proportions, spreading 100 feet or more under ideal growing conditions. The world’s largest known wisteria, located in Sierra Madre, Calif., was planted in 1894 and covers more than one acre.

Why does wisteria make loud popping noises?

Wisteria is a member of the pea family (Fabaceae), and similar to sweet pea vines, it produces long (but poisonous) seedpods after the flowers fade. When the pods ripen and turn brown, they explode with enough force to eject the seeds far away from the parent plant. This is Mother Nature’s way of preventing the overcrowding of seedlings, so they can germinate and grow without competition.

How long will wisteria live?

Planting wisteria is a long-term commitment. If you put a plant in the ground now, it may still be blooming and growing a century later if left undisturbed. One of the oldest wisteria vines, located in Japan’s Ashikaga Flower Park, dates back to 1870.


Q: I love wisteria but am having a hard time with it here in Minnesota. It’s not making much progress up my wooden arbor. – James A. Reider, White Bear Lake, Minn.

A: Your wisteria is root-hardy, but all the top growth it puts on each year is killed by severe winter temperatures. No wonder it’s not getting anywhere on your arbor. The two most common wisterias are W. sinensis and W. floribunda; the latter is a bit hardier. Its flower clusters are longer and more fragrant, but if your plant has never flowered, the best way to tell which one you have is the manner in which it twines: clockwise for W. floribunda, counterclockwise for W. sinensis. If you find you are growing the less hardy species, you might give W. floribunda a whirl, or even better yet, the native W. macrostachya. You might also consider wrapping the new growth in burlap for a little extra protection. If swaddling it is out of the question, you may have to settle on another vine. Incidentally, I hope your arbor is made of strong, thick timber: wisteria’s anacondalike stems have brought down many a finely wrought Victorian porch and gazebo.

Americans seem to have a strong distrust of vines; we grow them much less than other garden plants. It probably comes from a Freudian hang-up about lush, twining, probing shoots and tendrils or, more likely, our fear of the self-important, strangling imported thugs we see taking over in nature – porcelain berry, Hall’s honeysuckle, and kudzu. I’d like to see increased use of vines and more imaginative ways of growing them. Why not plant different vines at the base of your arbor and let them fight it out? You’ll have more interesting foliage shapes and textures and more flowers over a longer period of time. And, should some prove not as hardy or as vigorous as others, you won’t be left with a bare arbor. Why not be Darwinian and let the tough Minnesota winters weed out the weaklings?

Try trumpet creeper — the plain red species (Campsis radicans), not the named varieties that are less hardy — for its deep-green foliage and wonderful junglelike red flowers in late summer. It’s vigorous and can climb up a wooden arbor unassisted. Native Dutchman’s pipe (Aristolochia macrophylla) is a gamble in hardiness, but give it a try. It’s rambunctious and casts a deep shade with its large, tropical-looking leaves. A hardy, fast-growing native whose foliage turns scarlet in the fall is Virginia creeper (Parthenocissus quinquefolia).


Flowering Vines


Listeriosis can cause a variety of symptoms, depending on the person and the part of the body affected. Listeria can cause fever and diarrhea similar to other foodborne germs, but this type of Listeria infection is rarely diagnosed. Symptoms in people with invasive listeriosis, meaning the bacteria has spread beyond the gut, depend on whether the person is pregnant.

  • Pregnant women: Pregnant women typically experience only fever and other flu-like symptoms, such as fatigue and muscle aches. However, infections during pregnancy can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.
  • People other than pregnant women: Symptoms can include headache, stiff neck, confusion, loss of balance, and convulsions in addition to fever and muscle aches.

People with invasive listeriosis usually report symptoms starting 1 to 4 weeks after eating food contaminated with Listeria; some people have reported symptoms starting as late as 70 days after exposure or as early as the same day of exposure.

Learn more >

Leave a Reply

Your email address will not be published. Required fields are marked *