Prevention of rabies in travelers is best accomplished by having a comprehensive strategy. Such a strategy consists of 1) avoiding animal bites; 2) knowing how to prevent rabies after a bite; and 3) being able to travel (even to another country) to wherever postexposure prophylaxis (PEP) is available. To our knowledge, no traveler has died while trying to obtain PEP. The few travelers who have died of rabies received either no or inadequate PEP.
Travelers to rabies-enzootic countries should be warned about the risk of acquiring rabies and educated in animal bite-prevention strategies. Travelers should avoid feral animals, be aware of their surroundings so that they do not accidentally surprise a dog, and avoid contact with bats and other wildlife. A particular risk for a bite exposure is from monkeys who live near temples and other urban areas of Asia. Tourists to these sites should not carry any food on their person or in their backpack, purse, or other bag and should be careful not to approach or otherwise interact with monkeys. Casual exposure to cave air is not a concern, but visitors should be educated not to handle bats or other wildlife. Many bats have tiny teeth, and not all wounds may be apparent, compared with the lesions caused by carnivores. Any suspected or documented bite or scratch from a bat should be grounds for seeking PEP.
Children are at higher risk for rabies exposures because of their smaller stature, which makes extensive bites more likely; their curiosity and attraction to animals; and the possibility that they may not report a possible exposure. Although licks to fresh wounds or mucus membranes are a theoretical risk of acquiring rabies and PEP should be considered, there are no documented examples of rabies in travelers who were exposed in this manner.
For certain international travelers, preexposure rabies vaccine may be recommended, based on the prevalence of rabies in the country to be visited, the availability of appropriate antirabies biologics, intended activities, and duration of stay. A decision to receive preexposure rabies immunization may also be based on the likelihood of repeat travel to at-risk destinations or taking up residence in a high-risk destination. Preexposure vaccination may be recommended for veterinarians, animal handlers, field biologists, cavers, missionaries, and certain laboratory workers. Table 3-15 provides criteria for preexposure vaccination. Serology for rabies virus neutralizing antibodies is used as one gauge for revaccination considerations. Lists of US laboratories performing rabies serology may be found on the CDC website (www.cdc.gov/rabies). Regardless of whether preexposure vaccine is administered, travelers going to areas with a high risk for rabies should be encouraged to purchase medical evacuation insurance (see Chapter 2, Travel Insurance, Travel Health Insurance, & Medical Evacuation Insurance).
In the United States, preexposure vaccination consists of a series of 3 injections with human diploid cell rabies vaccine (HDCV) or purified chick embryo cell (PCEC) vaccine. The schedule for this series is given in Table 3-16. Travelers should receive all 3 preexposure immunizations before travel. If 3 doses of rabies vaccine cannot be completed before travel, the traveler should not start the series, as it would be problematic to plan PEP after a partial immunization series.
Preexposure vaccination does not eliminate the need for additional medical attention after a rabies exposure, but it simplifies PEP. Preexposure vaccination may also provide some degree of protection when there is an unrecognized exposure to rabies virus and when PEP might be delayed. Travelers who have completed a 3-dose preexposure rabies immunization series or have received full PEP are considered preimmunized and do not require routine boosters, except after a suspected rabies exposure. Periodic serum testing for rabies virus neutralizing antibody is not necessary in routine international travelers.
Any animal bite or scratch should be thoroughly cleaned with copious amounts of soap and water. This local care will substantially reduce the risk for rabies. Wounds that might require suturing should have the suturing delayed for a few days. If suturing is necessary to control bleeding or for functional or cosmetic reasons, rabies immune globulin (RIG), if indicated, should be administered into the wound before closing. The use of local anesthetic is not contraindicated in wound management.
In the event of a possible rabies exposure in someone who received preexposure rabies vaccination, 2 boosters of an acceptable rabies vaccine are given on days 0 and 3 after the exposure. The booster doses should be modern cell culture vaccines, but they do not have to be the same brand as the vaccine given in the original preexposure immunization series.
If preexposure rabies vaccination has not been given, PEP consists of injections of RIG (20 IU/kg) and a series of 4 injections of rabies vaccine over 14 days (or 5 doses over a 1-month period in immunosuppressed patients, Table 3-17). After wound cleansing, as much of the calculated amount of RIG (Table 3-17) as is anatomically feasible should be infiltrated around the wound, striving to put the RIG in the areas where the animal’s teeth and saliva have come in contact with the wound. The dose injected around the wound may be as small as 0.5 mL if the wound is small or on a finger. If the wounds are extensive, the calculated dose of RIG must not be exceeded. If the calculated dose is inadequate to inject all the wounds, the RIG should be diluted with normal saline to extend the number of wounds that can be injected. This is a particular issue in children, whose body weight may be small in relation to the size and number of wounds.
The remainder of the RIG dose, if any, should be injected intramuscularly. Care should be taken to guarantee that this remaining amount of RIG is deposited in a muscle and not injected subcutaneously, which may decrease its effectiveness. The remaining RIG can be given in the deltoid muscle, on the opposite side of the initial vaccine dose. The anterior thigh is an alternative site.
RIG should not be given >7 days after the start of the PEP series. This 7-day period does not relate to the time of the bite exposure itself. Initiation of PEP, including RIG infiltration, should begin after a bite exposure, even if there has been a considerable delay between the exposure and the traveler presenting for evaluation.
Human RIG is manufactured by plasmapheresis of blood from hyperimmunized volunteers. The manufactured quantity of human RIG falls short of worldwide requirements, and it is not available in many developing countries. Equine RIG or purified fractions of equine RIG have been used effectively in some developing countries where human RIG might not be available. If necessary, such heterologous products are preferable to no RIG.
The incidence of adverse events after the use of modern equine-derived RIG is low (0.8%–6.0%), and most reactions are minor. However, such products are not evaluated by US standards or regulated by the Food and Drug Administration, and their use cannot be recommended unequivocally. In addition, unpurified antirabies serum of equine origin might still be used in some countries where neither human nor equine RIG is available. The use of this antirabies serum is associated with higher rates of serious adverse reactions, including anaphylaxis.
Different PEP schedules, alternative routes of administration, and other rabies vaccines besides HDCV and PCEC may be used abroad. Although not approved for sale in the United States, purified Vero cell rabies vaccine and purified chick embryo cell vaccine (manufactured abroad) are acceptable alternatives if available in a destination country. Assistance in managing complicated PEP scenarios may be obtained from experienced travel medicine professionals, health departments, and CDC.
Rabies vaccine was once manufactured from viruses grown in animal brains, and some of these vaccines are still in use in developing countries. Typically, the brain-derived vaccines can be identified if the traveler is offered a large injection (5 mL) daily for approximately 14–21 days. The traveler should not accept these vaccines, but rather travel to where acceptable vaccines and RIG are available.
Travelers should be advised that they may experience local reactions after vaccination, such as pain, erythema, swelling, or itching at the injection site, or mild systemic reactions, such as headache, nausea, abdominal pain, muscle aches, and dizziness. Approximately 6% of people receiving booster vaccinations with HDCV may experience an immune complex–like reaction characterized by urticaria, pruritus, and malaise. The likelihood of these reactions may be less with PCEC. Once initiated, rabies PEP should not be interrupted or discontinued because of local or mild systemic reactions to rabies vaccine.
Pregnancy is not a contraindication to PEP. In infants and children, the dose of HDCV or PCEC for preexposure or PEP is the same as that recommended for adults. The dose of RIG for PEP is based on body weight (Table 3-17).
CDC website: www.cdc.gov/rabies
View the original article here
Post a Comment