Viral Infections Diseases Herpes Simplex Biology Essay

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Doctors aren't sure how or why the varicella-zoster virus reactivates, but they believe your immune system's response to the virus weakens over the years after childhood chickenpox. When the virus reactivates, it travels through nerves, often causing a burning or tingling sensation in the affected area. Two or three days later, when the virus reaches the skin, blisters appear grouped along the affected nerve. The skin may be very sensitive and you may feel a lot of pain.

If you have had chickenpox, you are at risk of developing shingles. However, the virus doesn't reactivate in everyone who has had chickenpox. Shingles most often appears in people older than 50 and in people with weakened immune systems. If you are having treatment for cancer, for example you are more likely to get shingles. People with HIV commonly get shingles, which is often one of the first signs that the immune system is in trouble.

Your chance of getting shingles increase as you get older, although the disease can occur at any age. When shingles appears in children, which is uncommon, it usually is very mild. Up to 20% of people in the United States develop the disease at some point.


Shingles usually begins with a burning sensation, a mild itching or tingling or a shooting pain in a specific area of skin. The affected area usually is located only on one side of the chest, abdomen or face or on a portion of an arm or leg. The skin may be extremely sensitive, so that you may not be able to stand clothing touching or rubbing the area.

After about five days, the skin becomes red and mildly swollen, and a rash appears. Blisters may cluster in patches or form a continuous line that roughly follows the path of the infected nerve. The blisters may be painful or itchy, and some may be as large as the palm of your hand. Blisters continue to appear over two to seven days and eventually break, form crusts and then heal.

Shingles also can cause fatigue, a low-grade fever and mild muscle aches.


Shingles can be difficult to diagnose before visible signs of the disease appear. Once a rash and blisters appear, your doctor probably will diagnose shingles based on your symptoms and the appearance of your skin. Rarely, when the diagnosis is less certain, the doctor may scrape tissue, collect cells from the affected skin and examine them under a microscope for cellular changes consistent with a herpes zoster infection.

If you have a rash across the bridge of your nose or anywhere near your eyes, your doctor will include an ophthalmologist (eye doctor) in your care.


If your condition is diagnosed within 72 hours after the rash appears, your doctor may prescribe antiviral medication. Some antiviral medications used to treat shingles include acyclovir (Zovirax), famciclovir (Famvir) and valacyclovir (Valtrex). Antiviral medications may help to reduce the risk of developing chronic (long-lasting) pain from shingles. Sometimes antiviral medication is combined with prednisone (a corticosteroid based anti-inflammatory drug).

The skin rash and blisters should be rinsed gently once or twice per day with cool water. Your doctor may suggest that you use antibiotic ointment on open areas. Because the pain that accompanies shingles can be intense, your doctor probably will prescribe a pain medication. For post-herpetic neuralgia, different medications are often prescribed for the pain that lingers well after the rash has gone away. These drugs alter the way pain signals are perceived by our central nervous system. Examples include amitriptyline (Elavil, Endep), doxepin (Adapin, Sinequan) and gabapentin (Neurontin). When shingles affects the eyes, an eye specialist (ophthalmologist) should be consulted immediately.


Warts are actually benign tumors of the epidermis caused by a virus. The virus responsible is the human papillomavirus (HPV), a double-stranded DNA virus. The virus resides in the bottom layer of the epidermis and replicates into almost normal-looking skin. Different sub-types of HPV cause different types of warts. Some human papillomavirus subtypes also cause cervical cancer and other more obscure types of wart-related cancers.


Warts normally grow out of the skin in cylindrical columns. These columns do not fuse when the wart grows on thin skin such as the face. On thicker skin, the columns fuse and are packed tightly together giving the surface the typical mosaic pattern. Black dots can sometimes be seen in a wart. These are actually blood vessels that have grown rapidly and irregularly into the wart and have thombosed or clotted off.


Warts can occur in people of all ages, but occur most commonly in children and young adults. They spread by direct contact, simply by touching the wart. Warts normally resolve spontaneously but the time it takes for this resolution is variable. Most warts resolve within weeks or months, but some may take years. It appears that a person's susceptibility to warts and the time it takes for them to go away is related to the individual's immune system. People who have immune-related diseases such as AIDS and lymphoma, or who are taking chemotherapy tend to have more warts that last longer.


Most warts can be treated with simple over-the-counter remedies. For those that are resistant to these measures, other types of treatments are effective.

Salicylic acid is a very common and effective over-the-counter treatment, but requires consistent application every day. They best way to use salicylic acid is to first pare the wart with a blade, pumice stone, emory board, or small scrub brush. Soaking the wart in warm water will aid in the absorption of the medicine. Salicylic acid is applied to the wart and allowed to dry. Normal surrounding skin may be protected with petroleum jelly. Occluding the treated wart with a band-aid or piece of tape also improves the absorption of the medicine. This procedure should be repeated daily ideally around shower or bath time. Salicylic acid can be found in several forms including a thick oil, or incorporated into an adhesive plaster form.

Cryotherapy is another effective treatment of warts. A provider applies liquid nitrogen as a spray or on a cotton swab to the wart. This freezes and kills the effected cells. The connective tissue is not destroyed; therefore, the lesion usually heals without significant scarring. The human papillomavirus is not killed by cryotherapy and is released into the surrounding tissue allowing the immune system to kill it. A blister typically forms on the site treated crusts over, and falls off. Since blisters are painful to walk on, cryotherapy is not a first choice for warts on the bottom of the foot.

Other medicines may be applied to warts or injected into them include lactic acid, trichloroacetic acid (TCA), formalin, glutaraldehyde, cantharidin, podopyllin, retin-A, and bleomucin. These treatments should be supervised by a health care provider.



The flu is a contagious respiratory disease caused by an influenza virus. The viruses that typically cause the flu are primarily categorized as influenza type A or type B. Influenza type B does not change much over time, but type A can mutate rapidly. Therefore, a new form of the flu vaccine must be developed each year to protect people against the exact strains that are expected to be most prevalent.

There are two types of flu vaccines: a flu shot and a nasal spray-type vaccine.

The flu shot contains killed (inactive) viruses, so it is not possible to get the flu from this type of vaccine. However, some people do get a low-grade fever for a day or two after the shot as their immune systems gear up to recognize the virus. The flu shot is approved for people age 6 months and older.

A nasal spray-type flu vaccine called Flu Mist uses a live, weakened virus instead of a dead one like the flu shot. It is approved for healthy people aged 2 to 49. The vaccine helps the lining of the nose fight off actual viral infections. It should not be used in those who have asthma or children under age 5 who have repeated wheezing episodes.

Flu vaccines are generally given at the beginning of the "flu season" -- usually late October or early November in the U.S. However, they may be given as late as March, and still provide some benefit.

People traveling to other countries should be aware that the flu may occur at different times.


According to the U.S. Centers for Disease Control and Prevention, anyone who wants to reduce their risk of the flu should get a flu vaccine. The flu shot is for people age 6 months and older. Some people are more likely to get the flu or to have a severe infection if they catch it. People at risk for more serious flu infections should always get a flu vaccine every year.

Older children and adults only require a single shot each year. However, children under age 9 need two shots 1 month apart the first time they receive flu vaccine or if they have not previously received two doses during one flu season.

The following people should get a flu shot every year.

Children between the ages of 6 months and 18 years

Children over age 5 who have a higher risk for serious illness

Children under age 18 who take long-term aspirin therapy

Household contacts and caregivers of children or adults with high-risk conditions (Breastfeeding women may receive the vaccine.)

You should get a flu shot every year if you:

Are 50 or older

Are a health care worker

Have chronic lung or heart disease

Have sickle cell anemia or other hemoglobinopathies

Live in a nursing home or extended care facilities

Live with people who have chronic health problems

Have kidney disease, anemia, severe asthma, diabetes, or chronic liver disease

Have a weakened immune system (including those with cancer or HIV/AIDS)

Receive long-term treatment with steroids for any condition

Are a pregnant woman

Are a woman who will be pregnant during flu season

The flu shot is encouraged for:

People who have in-home contact with children who are younger than 5 years old

People who provide essential community services

People living in dormitories or other crowded conditions

Any adult ages 18 - 50 who wants to reduce their chance of getting influenza


Most people have no side effects from the flu shot. Soreness at the injection site or minor aches and low grade fever may be present for several days.

Unlike the swine flu vaccine used in 1976, flu vaccines in recent years have shown no association with Guillain-Barre Syndrome (GBS) in children, and an extremely small increase in the risk of GBS in adults. This risk is far outweighed by the number of severe flu cases prevented by immunization.

As is the case with any drug or vaccine, there is a rare possibility of allergic reaction.

The regular seasonal flu shot has been shown to be safe for pregnant women and their babies. Most people have no side effects from the flu shot. Soreness at the injection site or minor aches and low grade fever may be present for several days.

Normal side effects of the nasal spray flu vaccine include fever, headache, runny nose, vomiting, and some wheezing. Although these symptoms sound like symptoms of the flu, the side effects do not become a severe or life-threatening flu infection.


According to the CDC, some people should not be vaccinated without first talking to a doctor. In general, you should not get a flu shot if you:

Had a severe allergic reaction to chickens or egg protein

Have a fever or illness that is more than "just a cold"

Had a moderate to severe reaction after a previous flu vaccine

Developed Guillain-Barre syndrome within 6 weeks after receiving a flu vaccine



Tinea capitis is the scientific name for ringworm on the scalp. Tinea capitis is common in children, especially ages 3 to 7. The majority of these fungal infections are caused by two different fungi:

Trichophyton tonsurans

Microsporum canis


The fungi that cause tinea capitis produce spores that are shed into the infected child's clothing, brushes or combs, and even into the air around the child. These spores can survive for months on objects. Children get tinea capitis after they come in contact with an infected person or animal, or after they come in contact with spores in other ways. For example, one common source of spores is classmates or adults who carry the spores on their skin or scalp without being infected.

The following factors increase a child's chance of getting a tinea capitis infection:

Having a large family

Crowded conditions

Low socioeconomic status


The most common symptom of tinea capitis is hair loss. There is also a rash, which can look different depending on whether the fungus gets inside the hair shaft or stays on the outside of the hair shaft. Common appearances include:

Black dot: A patch of hair loss with black dots on the scalp caused by hairs that are broken off just below the surface of the skin

Gray patch: Areas of hair loss with dry, scaly patches on the scalp

Kerion: Areas of hair loss with boggy, thickened scalp and pustules caused by the immune system's exaggerated response to the fungal infection


Tinea capitis is diagnosed by several methods. A wood's lamp examination may show hairs that turn blue-green. A KOH test on the hair or scalp may show fungi under the microscope. Finally, a fungal culture of the hair or scalp may show what type of fungus is causing the infection


It is important to note that tinea capitis cannot be treated with topical antifungal creams. It has to be treated with oral antifungal medications, sometimes for several months. Common antifungal medications used include:


Lamisil (terbinafine)

Sporanox (itraconazole)

Diflucan (fluconazole)



Athlete's foot, also called tinea pedis, is a common fungal infection of the skin of the feet. This fungus is contagious and therefore it generally is contracted through direct or indirect contact in public places (like showers or locker rooms). Once transmitted, the fungus grows in warm and moist environments, including footwear. Athlete's foot may last a very short time or may be long-term and recurring.


Itching, most notably in the creases between your toes

Redness and scaling of the skin in affected areas


Blisters or open sores

Cracked or blistered skin

Discoloration, thickening, crumbling of the nails as the fugus progresses


The best treatment for athlete's foot is proper foot care and hygiene in order to prevent the infection in the first place. Once athlete's foot has developed, self-care can usually help to eradicate the fungus. The skin of the foot should be kept clean and dry. Wash the feet with warm soap and water and rinse completely. Dry the area carefully by patting dry, rather than rubbing, the outer layers of skin. Wear clean socks and change socks and shoes often. Over-the-counter antifungal powders or creams may help control the infection. Ask the pharmacist for information about medication for athlete's foot, and follow the application instructions. It may take several weeks for this treatment to be effective. Severe or chronic infection may require further treatment by your doctor.



Scabies, infection with the Sarcoptes scabei mite, is not always a sexually transmitted disease. Unlike crabs, which is almost always transmitted sexually, scabies can also be passed between members of a household by skin-to-skin contact, shared clothing, towels, and bedding. The mites can live for up to 3 days outside of the human body. Unfortunately, it may be difficult to tell how you got infected, because symptoms can take up to 4 to 6 weeks to appear after initial exposure, and last for up to 2 to 3 weeks after treatment. Scabies causes a skin rash that primarily shows up on folds of skin, such as between the fingers, on the wrists and ankles, and in the genital area.


The scabies rash is hard to miss. It is most frequently found between the fingers, and on the wrists and ankles, but it can appear elsewhere as well.


There are several ways that your doctor can determine if your rash that's making you itch so much is caused by scabies. Most of the time, a doctor can diagnose you just by looking at the rash, but sometimes further testing may be needed.


Scabies are treated with topical pesticides. However, you also need to decontaminate your home.



Head lice infect hair on the head. They are easiest to see on the neck and over the ears. Tiny eggs on the hair look like flakes of dandruff. However, instead of flaking off the scalp, they stay put.

Head lice can survive up to 30 days on a human. Their eggs can live for more than 2 weeks.

Head lice spread easily. You can get head lice when you come in close contact with a person who has lice, or by touching their clothing or bedding. Head lice are more common in close, overcrowded living conditions. Lice spread easily among school children.

Having head lice does NOT mean the person has poor hygiene or low social status.

Having head lice causes intense itching, but does not lead to serious medical problems. Unlike body lice, head lice never carry or spread diseases.


Intense itching of the scalp

Small, red bumps on the scalp, neck, and shoulders (bumps may become crusty and ooze)

Tiny white specks (eggs, or nits) on the bottom of each hair that are hard to get off

Lice on scalp and clothing may be difficult to see, unless the infestation is heavy. If you see something moving, it's called a louse.


Lotions and shampoos containing 1% permethrin (Nix) often work well. They can be bought at the store without a prescription. If these do not work, a doctor can give you a prescription for stronger medicine. Such medicine should be used exactly as directed.

To use the medicine shampoo, first rinse and dry the hair. Then apply the medicine to the hair and scalp. After 10 minutes, rinse it off. Check for lice and nits again in 1 week and repeat the treatment if necessary.

An important part of treatment is removing the eggs (nits). Certain products make the nits easier to remove. Some dishwashing detergents can help dissolve the "glue" that makes the nits stick to the hair shaft.

You can remove the eggs with a nit comb. Before doing this, rub olive oil in the hair or run the metal comb through beeswax. This helps make the nits easier to remove.

Metal combs with very fine teeth are stronger and more effective than plastic nit combs. These metal combs are easier to find in pet stores or on the Internet than in pharmacies.

Removing eggs may prevent the lice from returning if the medication fails to kill every one of them.

Treat children and adults with lice promptly and thoroughly.

Wash all clothes and bed linens in hot water with detergent. This also helps prevent head lice from spreading to others during the short period when head lice can survive off the human body

Repeat combing for nits in 7-10 days.




A furuncle is an infection of the pilosebaceous unit, therefore is more extensive than a folliculitis because the infection also involves the sebaceous gland. A furuncle frequently occurs on the neck, face, armpits, and buttocks. It begins as a small, tender, red nodule that becomes painful and fluctuant. Frequently, pus will spontaneously drain, and often the furuncle will resolve on its own. Factors that contribute to the development of furuncles include:


Blood disorders

Taking oral steroid medications



Folliculitis is an infection that is localized to the hair follicle. A folliculitis looks like small, yellow pustules that are confined to the hair follicle. Factors that can lead to the development of a folliculitis include:


Chronic friction

Occlusive clothing

Occlusive chemicals

Excessive sweating

Exposure to water


Mild cases of folliculitis and small furuncles may heal on their own with good hygiene and wound care. More extensive furuncles and all carbuncles need to be treated with antibiotics such as dicloxacillin or cephalexin. If pus or indurations are present, in addition to antibiotics, a procedure called incision and drainage (I&D) should be performed to drain the pus and allow the lesion to heal from the inside out.


Impetigo is a common bacterial infection of the upper layers of the skin caused by streptococcus pyogenes and staphylococcus aureus. It is highly contagious and usually treated with a topical antibiotic.


Warm, humid climate or environment

Traumatized skin

Poor hygiene


Nasal colonization with bacteria


Impetigo is treated with the topical antibiotic mupirocin (Bactroban) applied to the lesion four times a day until the lesion is gone for three days. Bullous impetigo and resistant non-bullous infections are treated with oral antibiotics. Pencillin and amoxicillin are not good antibiotics to use because of increasing resistance rates. Antibiotic classes that are effective include the macrolides (erythromycin, azithromycin, or clarithromycin) and the cephalosporins (cephalexin, cefprozil or cefdinir).