Rabies

Rabies, one of the world’s oldest diseases, is most commonly transmitted through the saliva of an infected mammal but is also known to spread via the airborne route. There are an estimated 55,000 deaths worldwide each year from rabies.³ In the United States, however, prevention measures have resulted in only one or two actual cases developing in the 16,000 to 39,000 individuals exposed to potentially rabid carnivores and bats.⁴ The Centers for Disease Control and Prevention (CDC) reported in 2007 that the canine strain of rabies has been eliminated in the United States, and most human incidents of rabies are now the result of exposure to wildlife such as bats, raccoons, skunks, and foxes.⁴

Signs and Symptoms

• Initial stage rabies includes paresthesias, pain, or itching at the bite site. This is thought to be related to viral replication and may progress over several days to a week. The incubation period is usually 1 to 3 months but can vary from days to years.³

• Prodrome stage rabies includes nonspecific findings such as headache, fever, runny nose, sore throat, myalgias, and gastrointestinal symptoms. The virus progresses along the peripheral nervous system toward its ultimate destination: the central nervous system.

• Acute, progressive encephalitis includes:

• Hydrophobia, an overwhelming fear of seeing or feeling water, is considered pathognomonic for rabies.

• Aerophobia, a fear elicited by the movement of air.

Prevention

Once the virus becomes established in a human, the disease is almost 100% fatal. However, early aggressive wound management is suggested to prevent viral replication. This includes the following interventions:

• Scrub (do not irrigate) with a virucidal agent such as povidone-iodine (Betadine).

• Soap is preferred over plain water if povidone-iodine is not available.

• Sunlight and drying also kills the rabies virus.

Postexposure Prophylaxis

Postexposure prophylaxis is imperative (Table 32-1). For those who have not previously been exposed, the rabies vaccine human rabies immunoglobulin provides rapid, passive immunity. When the rabies vaccine is administered properly, detectable rabies virus neutralizing antibodies have been shown to develop in approximately 7 to 10 days.⁴ These antibodies persist for several years. Reactions to prophylactic therapies are rarely severe.⁴

TABLE 32-1 RABIES POSTEXPOSURE PROPHYLAXIS

THOSE NOT PREVIOUSLY VACCINATED FOR RABIES (i.e., GENERAL PUBLIC)	THOSE PREVIOUSLY VACCINATED FOR RABIES (i.e., VETERINARIANS)
Immediate aggressive cleaning and scrubbing of wound with virucidal agent (rinse with water or saline and dry after).	Immediate aggressive cleaning and scrubbing of wound with virucidal agent (rinse with water or saline and dry after).
Administer human rabies immunoglobulin (20 IU/kg or 0.133 mL/kg). If anatomically feasible, inject as much as possible directly into proximal area of wound (virus will travel along nerve tracts toward the central nervous system). Any remaining volume is administered intramuscularly at a site distal to the vaccine site.	Do not administer rabies immunoglobulin.
Administer human diploid cell vaccine or purified chick embryo 1 mL dose on days 0, 3, 7, and 14.^a	Administer human diploid cell vaccine or purified chick embryo 1 mL dose on days 0 and 3.^a

Note: More detailed information is available from Centers for Disease Control and Prevention.

^a Mitka, M. (2010). CDC advisors suggest streamlining postexposure prophylaxis for rabies. Journal of the American Medical Association, 303(16), 1586.

Data from Centers for Disease Control and Prevention. (2010). Use of a reduced (4-dose) vaccine schedule for postexposure prophylaxis to prevent human rabies: Recommendations of the Advisory Committee on Immunization Practices. MMWR Recommendations and Reports, 59(RR-2), 1–9.

Tick-Borne Illnesses

Ticks are responsible for a number of illnesses in humans and are second only to mosquitoes as a vector for disease transmission. With strong jaws and a cementlike adhesive, ticks attach to humans, other mammals, birds, and reptiles. Ticks engorge themselves on blood and transmit disease through their saliva. Because their digestive tract has no exit (anus), when they are well fed they burst, spreading potential pathogens.

Unfortunately, because of the tick’s small size many people are unaware that they have been bitten. Initial symptoms are often nonspecific but a history of travel or a characteristic rash can provide clues. Search for the tick if it is suspected. It is most often in the scalp but may also reside in the axilla, pubic or perianal area, popliteal fossa, or ear canal.

Table 32-2 lists a sampling of common tick-borne illnesses that occur in the United States. In addition to spreading infection, certain ticks contain a neurotoxin that can induce tick paralysis. This disease is characterized by a descending paralysis that resembles Guillain-Barré syndrome. Paralysis quickly resolves when the tick is removed.

TABLE 32-2 COMMON TICK-BORNE ILLNESSES

Tick Removal ^5,⁶

Ticks should be removed as soon as possible to decrease the amount of time for microorganisms to be transferred to the host. Guidelines for safe tick removal are included in Table 32-3 and depicted in Figure 32-1. Avoid squeezing or crushing the tick, as this may cause the inadvertent release of the tick’s internal contents. Avoid handling the tick. Occasionally, the tick may be sent to a local laboratory or health department for analysis and evaluation.

TABLE 32-3 TICK REMOVAL

Fig. 32-1 Tick removal technique.

(From Raoult, D. [2008]. Rickettsioses. In L. Goldman & D. Ausiello [Eds.], Cecil medicine [23rd ed.]. Philadelphia, PA: Saunders.)

Prevention

Avoidance of tick habitats is the best prevention measure. Table 32-4 lists ways to avoid tick exposure that can be included in patient discharge instructions.

TABLE 32-4 AVOIDING TICK-BORNE ILLNESS

Awareness

• Ticks live in moist, wooded, bushy, or grassy areas. Avoid thick underbrush and stay near the center of trails.

• Perform a “tick drag” to determine whether ticks exist in a specific area. Drag a 3-foot stick with white flannel on each end across an area of concern several times. Examine the stick and flannel to identify any ticks that have latched on.

Clothing

• Wear light-colored clothing. This makes it easier to see ticks.

• Wear long-sleeved shirts tucked into pants and pants tucked into socks or boot tops. Wear a hat.

Insect Repellent

• Use a 35% DEET (N,N-Diethyl-m-toluamide) product on exposed skin (not under clothes).

• Use permethrin-containing products on clothing, footwear, and camping gear.

Inspection

• After spending time outdoors, check your entire body for ticks. Shower afterward.

• Check clothes for ticks. Launder immediately. A hot dryer will kill ticks.

• Check pets for ticks. Use a tick collar.

Early Removal

• If a tick is identified, remove it in a timely manner. Save it for a health care provider in a baggie or sealed container.

• Wash area. Observe area over time for development of rash or other symptoms.

Notify a Health Care Provider

• Always advise your health care provider if you have removed a tick or have been in a tick-prone area and develop signs or symptoms of illness.

Always report removal of a tick to a health care provider.

Snakebites

Only about 5 to 10 individuals die annually in the United States as a consequence of a snakebite.² The actual incidence of snakebites is estimated at 45,000, with 7000 to 8000 from venomous snakes.² Most bites occur when handling, teasing, or playing with snakes and 40% of persons bitten have a blood alcohol level greater than 0.1%.⁷ Around 85% of bites are on the fingers or hand and 15% involve the foot or ankle.⁷

Of the 120 species of snakes indigenous to the United States, only 20 (from four different species) are venomous. Three of the species of poisonous snakes are from the family known as pit vipers (Crotalidae): rattlesnakes, copperheads, and cottonmouths (also known as water moccasins). The fourth species of poisonous snake is the coral snake, which looks similar to the nonvenomous king snake.