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Chapter 2The Pre-Travel ConsultationCounseling & Advice for Travelers

Animal-Associated Hazards

Nina Marano, G. Gale Galland

HUMAN INTERACTION WITH ANIMALS: A RISK FACTOR FOR INJURY AND ILLNESS

Animals tend to avoid humans, but they can attack if they perceive threat, are protecting their young or territory, or are injured or ill. Although attacks by wild animals are more dramatic, attacks by domestic animals are far more common, and secondary infections of wounds may result in serious systemic disease. In addition, animals can transmit zoonotic infections such as rabies. Of the estimated 35,000–55,000 rabies deaths every year worldwide, >95% occur as a result of dog bites in the developing countries of Africa and Asia. A recent 10-year retrospective review of dog bites in Austria showed that 75% of the bites were preventable because the person had intentionally interacted with the dog.

BITE OR SCRATCH WOUNDS

Animal bites present a risk for rabies, tetanus, and other bacterial infections. Animals’ saliva can be so heavily contaminated with bacteria that a bite may not even be necessary to cause infection if the animal licks a preexisting cut or scratch. Young children are more likely to be bitten by animals and to sustain more severe injuries from animal bites.

Prevention

Before departure, travelers should have a current tetanus vaccination or documentation of having received a booster vaccination within the previous 5–10 years. Travel health providers should assess a traveler’s need for preexposure rabies immunization according to the guidelines in Table 3-15. While traveling, people should never try to pet, handle, or feed unfamiliar animals (whether domestic or wild, even in captive settings such as game ranches or wild animal petting zoos), particularly in areas where rabies is endemic. To mitigate the risk of exposure to rabies, dogs and other mammals should be avoided.

Management

In order to prevent infection, all wounds should be promptly cleaned with soap and water, and the wound promptly debrided, if necrotic tissue, dirt, or other foreign materials are present. These steps of wound care are especially important for tetanus- or rabies-prone wounds (see the Rabies and Tetanus sections in Chapter 3). Travelers who might have been exposed to rabies should contact a reliable health care provider as soon as possible for advice about rabies postexposure prophylaxis. Travelers who received their most recent tetanus toxoid–containing vaccine >5 years previously, or who have not received ≥3 doses of tetanus toxoid–containing vaccines, may require a dose of tetanus toxoid–containing vaccine (Tdap, Td, or DTaP) according to ACIP guidelines.

MONKEYS

Macaques are native to Asia and North Africa. Additionally, descendants of North African populations of Barbary macaques inhabit Gibraltar, the only place that wild populations of macaques are found in Europe. They are also housed in research facilities, zoos, and wildlife or amusement parks and are kept as pets in private homes throughout the world. Monkey bites occasionally occur in certain urban sites, such as temples in Nepal or India.

Macaque bites can transmit herpes B virus, a virus related to the herpes simplex viruses that cause oral and genital ulcers. Herpes B infection is rare in humans. The virus was discovered in 1933, and since that time approximately 50 human cases have been reported, with an 80% case-fatality ratio. No cases of herpes B infection have been reported in people exposed to monkeys in the wild. Most documented cases have resulted from occupational exposures. However, travelers to areas where macaques range freely should be aware of the potential risk. A monkey infected with herpes B may appear completely healthy.

Documented routes of human infection with herpes B virus include animal bites and scratches, exposure to infected tissue or body fluids from splashes, and in one instance, human-to-human transmission. Even minor scratches or bites should be considered potential exposures, because, experimentally, herpes B virus has been isolated from surfaces for up to 2 weeks after it was applied. The incubation period ranges from <1 week to 1 month or longer. Neurologic symptoms develop as the virus infects the central nervous system and may lead to ascending paralysis and respiratory failure. Increased public and clinician awareness about the risks associated with an injury from a macaque, improved first aid after exposure, the availability of better diagnostic tests, and improved antiviral therapeutics have decreased the case-fatality ratio to 20% in treated people. As a result, from 1987 through 2004 only 5 infections were fatal.

Although only macaque bites pose a herpes B virus threat, any monkey bite may pose a threat for rabies.

Prevention

Travelers should never attempt to feed, pet, or otherwise handle any monkeys.

Management

After a monkey bite or scratch, travelers should be advised to thoroughly clean the wound and seek medical care immediately to be evaluated for possible rabies and herpes B postexposure prophylaxis. Additional information and photos of macaques can be found at the website for the National B Virus Resource Center at the Georgia State University Viral Immunology Center (www2.gsu.edu/~wwwvir).

BATS

Bats can be found almost anywhere in the world except the polar regions and extreme deserts. Bats are reservoir hosts for viruses that can cross species barriers to infect humans and other domestic and wild mammals. Viral infections such as rabies and viral hemorrhagic fevers can be transmitted from bats to people. It is not possible to tell if a bat has rabies; however, any bat that is active by day, is found where bats are not usually seen (for example, indoors or outdoors in areas near humans), or is unable to fly is far more likely to be rabid. A recent example of an imported case of Marburg fever in a tourist who had visited a “python cave” in western Uganda illustrates the risk of acquiring diseases from contact with cave-dwelling bats. This same cave was the source of a fatal case of Marburg hemorrhagic fever in a Dutch tourist in 2008. Exposure to bats can occur during adventure activities, such as caving or spelunking, and can include bites, scratches, and mucosal or cutaneous exposure to bat saliva. Like any other wild animal, bats, whether sick or healthy, will bite in self-defense if handled.

Prevention

Bats should never be handled. Travelers should be discouraged from going into caves or mines that have large bat infestations. Depending on the country being visited, preexposure rabies vaccination may be recommended for people engaged in activities such as caving.

Management

If a bite occurs or if infectious material (such as saliva) from a bat gets into the eyes, nose, mouth, or a wound, the traveler should wash the affected area thoroughly and get medical advice immediately. Any suspected or documented bite or scratch from a bat anywhere in the world should be grounds for seeking postexposure rabies immunoprophylaxis.

People usually know when they have been bitten by a bat. However, bats have tiny teeth, and not all wounds may be apparent. Travelers should seek medical advice even in the absence of an obvious bite wound if they wake up to find a bat in the room or see a bat in the room of an unattended child.

RODENTS

Rodents carry a variety of viral, bacterial, and parasitic agents that may pose a threat to human health. Human exposure can occur directly by a bite or scratch, or indirectly by exposure to surfaces or water contaminated with urine or feces. Rodents should never be handled. Travelers should avoid places that have evidence of infestation with rodents and should avoid contact with rodent feces. Travelers should not eat or drink anything that is suspected to be contaminated by rodent feces or urine.

Management

Wild rodents are unlikely to have rabies; however, each exposure needs to be evaluated as follows:

  • If the bite was provoked (such as through feeding, petting, or playing with the animal) and the animal appeared healthy, the animal was probably not rabid at the time of the bite. Most experts would not recommend postexposure prophylaxis in this situation.
  • If the bite was unprovoked or the animal appeared unhealthy and is unavailable for testing, rabies postexposure prophylaxis should be considered.

Travelers who were exposed to rodents and who develop febrile illness shortly after returning home should be evaluated by a clinician. Depending on the history and symptoms, diseases such as yersiniosis, plague, leptospirosis, hantavirus and rickettsial infections, Lyme disease, tickborne encephalitis, poxvirus, and bartonellosis (all discussed in further detail in Chapter 3) should be included in the list of possible diagnoses.

SNAKES

Poisonous snakes are hazards in many locations, although deaths from snakebites are rare. Snakebites usually occur in areas where dense human populations coexist with dense snake populations, such as Southeast Asia, sub-Saharan Africa, and tropical areas in the Americas.

Prevention

Common sense is the best precaution. Most snake bites result from startling, handling, or harassing snakes. Therefore, all snakes should be left alone. Travelers should be aware of their surroundings, especially at night and during warm weather when snakes tend to be more active. For extra precaution, when practical, travelers should wear heavy, ankle-high or higher boots and long pants when walking outdoors in areas possibly inhabited by venomous snakes.

Management

Travelers should be advised to seek immediate medical attention any time a bite wound breaks the skin or when snake venom is ejected into their eyes or mucous membranes. Immobilization of the affected limb and application of a pressure bandage that does not restrict blood flow are recommended first aid measures while the victim is moved as quickly as possible to a medical facility. Incision of the bite site and tourniquets that restrict blood flow to the affected limb are not recommended. Specific therapy for snakebites is controversial and should be left to the judgment of local emergency medical personnel. Specific antivenoms are available for some snakes in some areas, so trying to ascertain the species of snake that bit the victim may be critical.

INSECTS AND OTHER ARTHROPODS

Bites and stings from spiders and scorpions can be painful and can result in illness and death, particularly among infants and children. Other insects and arthropods, such as mosquitoes and ticks, can transmit infections. See the Protection against Mosquitoes, Ticks, & Other Insects & Arthropods section earlier in this chapter.

MARINE ANIMALS

Most marine animals are generally harmless unless threatened. Most injuries are the result of chance encounters or defensive maneuvers. Resulting wounds have many common characteristics: bacterial contamination, foreign bodies, and occasionally venom. Venomous injuries from marine fish and invertebrates are increasing with the popularity of surfing, scuba diving, and snorkeling. Most species responsible for human injuries, including stingrays, jellyfish, stonefish, sea urchins, and scorpionfish, live in tropical coastal waters.

Prevention

Travelers should be advised to maintain vigilance while engaging in recreational water activities. Prevention is the best defense:

  • Avoid contact. This may be difficult in conditions of poor visibility, rough water, currents, and confined areas.
  • Do not attempt to feed, handle, tease, or annoy marine animals.
  • Wear protective clothing, such as protective footwear.
  • Make an effort to find out which animals may be encountered at the destination and learn about their characteristics and habitats before engaging in recreational water activities.

Management

In case of injury, identifying the species involved can help determine the best course of treatment. Signs and symptoms may not appear for hours after contact, or the animal may not have been seen or recognized at the time of injury. In such cases treatment is based on the injury presentation. Symptoms of venomous injuries can range from mild swelling and redness at the site to more severe symptoms, such as difficulty breathing or swallowing, chest pain, or intense pain at the site of the sting, for which immediate medical treatment should be sought. Management will vary according to the severity of symptoms and can include medications, such as diphenhydramine, steroids, pain medication, and antibiotics.

BIRDS

Ill birds have been associated with cases of highly pathogenic avian influenza in humans. When traveling in an area where outbreaks of avian influenza have been reported, travelers should avoid contact with live poultry (such as chickens, ducks, geese, pigeons, turkeys, and quail) or any wild birds and should avoid settings where avian influenza A (H5N1)-infected poultry may be present, such as commercial or backyard poultry farms and live poultry markets. Travelers should not eat uncooked or undercooked poultry or poultry products, including dishes that contain uncooked eggs or poultry blood. Other pathogens from birds may infect humans through infected feces or by aerosol. These cause diseases such as histoplasmosis (see Chapter 3, Histoplasmosis), salmonellosis (see Chapter 3, Salmonellosis [Nontyphoidal]), psittacosis, and avian mycobacteriosis. Travelers should wash their hands if they come in contact with bird feces.

BIBLIOGRAPHY

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