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Just One Bite

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Vol. 20 •Issue 23 • Page 42
Just One Bite

Patients with West Nile virus can develop severe physical and neurological symptoms

In August of 2003, Ron's life changed drastically. At first, he and his family thought he had a severe case of the flu. Later, he became disoriented, started falling and experienced hallucinations.

Ron was immediately admitted to the hospital where he was diagnosed with viral meningitis. A few days later he tested positive for West Nile virus (WNV).

Ron was in a coma and on life support for three weeks. He spent ten days as an inpatient at a rehabilitation center and lost three months of income from the disabling effects of West Nile meningitis.

One year later, Ron continues to experience fatigue, short-term memory loss, difficulty with concentration and facial tremors. Although he has returned to work full-time and attempts his previous activity level, Ron still feels the debilitating effects of his condition. "I don't have the energy I did before West Nile virus," he says. "I feel like sleeping 12 hours a day now."

Transmission Cycle

Humans contract West Nile virus through mosquito bites. WNV is an arbovirus, a virus transmitted by an arthropod: the Culex mosquito.

The transmission cycle of West Nile virus initializes when a mosquito bites an infected bird, or vector. The virus takes up residence in the mosquito's salivary glands. A mosquito that has fed on an infected bird can infect humans and other animals, particularly horses. Infected female mosquitoes transmit WNV when they bite and take a blood meal.

WNV is not contagious and there is no evidence that an individual can contract WNV from handling birds or other animals. WNV cannot be transmitted through human touching or kissing; however blood transfusions and transplanted organs can transmit WNV from donor to recipient. Blood banks are currently more diligent in screening for the presence of WNV. A mother can also transmit WNV to her infant during pregnancy and breastfeeding.

West Nile in the U.S.

West Nile virus was first isolated from an adult woman in the West Nile District of Uganda in 1937. Today, WNV is most commonly found in Africa, west and central Asia, Oceania, Europe and the Middle East. West Nile virus first emerged in the Western Hemisphere in New York City during the summer of 1999.

In the United States from 1999 through September 2004, health care providers have documented cases of WNV in every state except Washington, Alaska and Hawaii. In the summer of 2003, Colorado led the nation with just under 3,000 reported cases, including 63 deaths. As West Nile virus continues to spread to the western United States, confirmed cases, including fatalities, are rising daily in Southern California.

Signs and Symptoms

Eighty percent of people who contract WNV are asymptomatic.

Approximately 20 percent of those infected will develop West Nile fever, which includes flu-like symptoms such as fever, tiredness, myalgias, gastrointestinal disturbances, swollen lymph glands, eye pain and occasionally a skin rash. The incubation period is around 3-15 days after being bitten by the infected mosquito. The duration of the illness is about 3-6 days.

Symptoms, however, can range from relatively mild to a more complicated and protracted illness. In more severe cases, WNV can result in encephalitis, meningitis or both. At this severity, the virus significantly affects the nervous system and is referred to as a "neuro-invasive disease." The CDC estimates that approximately 1 out of 150 infected people will develop a more severe form of the disease. Those past 50 years of age and people with suppressed immune systems are at greater risk of developing severe neurologic symptoms.

Symptoms of severe WNV can include severe headache, high fever, stiff neck, altered consciousness (confusion, stupor or even coma), photosensitivity, cranial nerve involvement (facial weakness, double vision, visual loss, decreased taste sensation), tremors, unsteady gait, dysphagia, respiratory distress, seizures, vomiting, muscle weakness, and in some cases West Nile poliomyelitis (an inflammation of the spinal cord that causes acute flaccid paralysis similar to that caused by the poliovirus) and paralysis. Neurological effects from the disease can be permanent.

Incidence of West Nile poliomyelitis, which was first recognized in the U.S. in 2002, is still unknown, according to the CDC. According to James Sejvar, MD, medical epidemiologist for the National Center for Infectious Diseases at the CDC, "those developing West Nile poliomyelitis tend to be younger and otherwise healthy." These patients may never recover fully. "In the short term, pretty much everyone continues to have some functional difficulties," Sejvar added.

WNV can be fatal in anywhere from 3-15 percent of the most severe cases, primarily among the elderly. Those who contract West Nile virus will develop immunity to any future West Nile infections.

Diagnosis and Treatment

West Nile virus may be present in blood, serum, tissues and the cerebro-spinal fluid (CSF) of infected humans, birds, mammals and reptiles. To date, serologic testing to detect immunoglobulin M (IgM) antibodies is the most proficient means for diagnosing West Nile virus infection. This test can be performed in state public health laboratories with results in 24-36 hours.

Medical care for WNV infection is supportive. Providers should administer analgesics to reduce fever and pain, fluids to prevent dehydration, and advocate bed rest. In severe cases, hospitalization is necessary. Patients hospitalized for WNV receive intravenous fluids and oxygen therapy, and are monitored for secondary infections such as deep vein thrombosis, pressure ulcers and pulmonary complications. In severe cases of neuro-invasive disease or West Nile poliomyelitis, mechanical ventilation will be necessary.

In an FDA-approved clinical trial supported by the National Institutes for Allergies and Infectious Diseases (NIAID), researchers are treating patients with WNV infection with immunoglobulin G antibodies isolated from individuals who have recovered from West Nile virus infection. Investigators compare this treatment to placebo treatments to assess safety and to determine whether or not these antibodies will help the patient fight off the severe symptoms of the disease.

In the summer of 2003, Nelson Gantz, MD, chief of infectious diseases at Boulder Community Hospital in Colorado and an expert in chronic fatigue syndrome, conducted a pilot study with AVI-4020, an antisense compound given by intravenous injection. Antisense drugs are designed to block genetic instructions, marking them for destruction by cellular enzymes, in order to prevent the building of new viruses or the infection of new cells. In this trial, the synthetic chemical compound works by mirroring a crucial segment of the virus's genetic code, thereby binding to the target RNA, and shutting down the virus. Patrick Iversen, vice-president for AVI BioPharma, announced that the company plans to launch a clinical trial of AVI-4020, which has received FDA approval.

The Role of Occupational Therapy

Patients infected with severe WNV often manifest symptoms similar to stroke, polio and post-polio syndrome, Guillan-Barre syndrome, fibromyalgia, viral meningitis and encephalitis, brain tumor, traumatic brain injury, chronic fatigue syndrome, multiple sclerosis and toxoplasmosis.

Occupational therapy's focus is on activities of daily living (ADLs), including bathing, hygiene, grooming, dressing and feeding. Treatment for functional mobility impairments should address transfer training and functional mobility within the patient's immediate environment.

Maximize upper extremity strength, range-of motion and coordination that affect ADLs, and address the cognitive issues that interfere with daily functioning. Instruction in energy conservation and work simplification techniques is imperative for ameliorating the limited endurance and frustration these patients experience on a daily basis from chronic fatigue.

The treating therapist should evaluate assistive and/or adapted devices to compensate for weakness, decreased balance and coordination. For example, a deltoid aid or overhead suspension sling can be set up for patients with proximal weakness to achieve self-feeding, hygiene and grooming activities. Built-up handles on utensils can assist patients with distal weakness to participate in self-care activities, and most importantly to provide them with a sense of control and independence.

In consultation with physical therapists, patients with unsteady gait due to ataxia or decreased balance may use walkers and canes for safe and independent ambulation. Patients with paralysis will require a wheelchair with an adequate cushion for pressure relief to prevent pressure sores.

Occupational and speech therapists should collaborate to devise strategies to assist patients with cognitive issues and evaluate safety at home. Decreasing environmental stimulation, presenting information slowly and instructing patients in the use of checklists can assist with decreased processing speed and attention, as well as short-term memory deficits. Patients who exhibit prolonged difficulty with cognitive functioning post WNV infection may benefit from neuropsychological evaluation and treatment.

In the sensory realm, the OT should address any loss of sensation or paresthesia, including possible visual and auditory disturbances. In cases of meningoencephalitis, optic neuritis can develop and result in diplobia (double vision) or vision loss. Sensory loss can result in decreased safety awareness and presents a greater risk for falls, pressure sores and potential burns.

Psychological support for patients and families from all members of the health care team is invaluable. West Nile virus is a potentially debilitating and frightening infection. Family members may be required to "pick up the slack" if a patient is unable to fulfill his or her previous role. In 2003, due to the high numbers of people infected in the Boulder area, Boulder Community Hospital established a WNV clinic at Mapleton Rehab Center to provide on-going support and treatment for survivors and their families.

Prevention

Since there is no vaccine for West Nile virus, personal protective measures and public health education are key for prevention of mosquito bites (see sidebar). Gantz explained, "a mosquito doesn't have a sign on it, 'I'm carrying the West Nile virus,' so you have to assume that every mosquito bite is a potential vector."

Mosquitoes breed in wet areas, and the Culex are found particularly where there is decaying organic matter such as leaves, grass clippings and animal wastes. The breeding season begins in spring and typically ceases in mid-October when the first frost appears. The peak season for WNV is during the summer months of August and September.

Ron, like many survivors of West Nile virus, will continue to live with the devastating effects of the infection. Many people will not be able to return to their previous employment or resume their prior roles. This can result in financial, psychological and social losses for all involved. Many survivors may feel isolated and traumatized by their illness.

As we gain more knowledge about this virus, the medical community is achieving greater efforts toward preventing its transmission and providing the best care for those who have been infected. n

References available at www.advanceweb.com/OT or upon request.

Carol Myers is an occupational therapist with over 20 years of experience. She worked with patients infected with West Nile virus at Boulder Community Hospital, CO, during the 2003 epidemic.

Preventing West Nile

The following guidelines are recommended for personal protection against mosquito bites:

• Avoid the outdoors from dusk until dawn.

• Dress in long sleeves, socks and pants when spending time outside

• Use DEET-enhanced insect repellent (N, N-diethyl-m-toluamide) when outdoors or in shady areas during the day. (The more DEET a repellent contains, the longer time it can protect you from mosquito bites). Apply to clothing since mosquitoes can bite through fabric.

• Do not use DEET on infants less than 6 months.

• Drain any standing water (such as old tires, wading pools, buckets and gutters).

• Aerate swimming pools and ponds and perhaps stock with mosquito eating fish.

• Make sure that windows and screens fit tightly and are free from holes.

• Keep grass cut short.

• Empty and clean bird baths at least once weekly.




     

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