© Springer International Publishing Switzerland 2017Francesco Feletti (ed.)Extreme Sports Medicine10.1007/978-3-319-28265-7_4
4. Infectious Diseases and Extreme Sports
Departamento de Medicina Preventiva, Faculdade de Medicina, Universidade Federal do Rio de Janeiro, Rua von Martius 325/608, Rio de Janeiro, CEP:22460-040, Brazil
Ricardo Pereira Igreja
KeywordsWilderness medical careCavingRaftingMultisport racesMalariaLeptospirosisMyiasisSchistosomiasisTickborne rickettsial diseasesKayakingRabiesVaccinationsProphylactic medications
Recent outbreaks of infectious diseases in competitive sports have stimulated considerable interest in the role of infections in the health of athletes. Sports provide an excellent opportunity for the transmission of communicable diseases to athletes, athletic staff, and social contacts, propagating the outbreak into the community. Furthermore, the increasing popularity of international sporting events is likely to expose athletes to indigenous diseases for which they have little, if any, natural immunity .
Adventure travel has led to an increasing risk for contact with pathogens uncommon in industrialized countries. Extreme sport athletes may be at increased risk because they often travel through poorer, rural areas of tropical and subtropical regions to reach their destinations. In addition, competitions can take place in extreme locations like jungles, mountains, or deserts. Risk from a specific infectious agent depends on the region of the world traveled, contact with food or water, and whether traveling in rural or urban area .
Common sources of exposure include contaminated lakes, rivers, caves, and canyons. Athletes may be exposed to insect vectors. African ticks were responsible for an outbreak of African tick-bite fever in participants of an Eco-challenge .
Besides the lack of immediate medical care that can complicate and worsen the severity of these diseases, these illnesses may be unfamiliar to practitioners in the travelers’ home countries, and symptoms may go unrecognized. Physicians caring for extreme sport competitors must take a careful travel and exposure history and have a high index of suspicion for unusual diseases.
4.2 Infectious Diseases and Extreme Sports
The following discusses infections that may be more likely to occur in the extreme sport athlete. Epidemiology, presentation, and prophylaxis are discussed for each of these diseases. Infections that were solely food borne were excluded.
Malaria continues to be a major global health problem, with over 40 % of the world’s population—more than 3.3 billion people—at risk for malaria to varying degrees in countries with ongoing transmission (transmission still occurs in 99 countries). In addition, with modern, rapid means of travel, large numbers of people from nonmalarious areas are being infected, which may seriously affect them after they have returned home. Plasmodium falciparum is common in the tropics and causes the most serious form of the disease. The risk of severe malaria is increased if treatment of an uncomplicated attack of malaria is delayed. As infections with this parasite can be fatal, recognizing and promptly treating uncomplicated malaria is therefore of vital importance. The presentation of uncomplicated P. falciparum malaria is highly variable and mimics that of many other diseases. Although fever is common, it may be absent in some cases. The fever is typically irregular initially and commonly associated with chills. The patient commonly complains of fever, headache, aches, and pains elsewhere in the body and occasionally abdominal pain and diarrhea. On physical examination, fever may be the only sign. In some patients, the liver and spleen are palpable. This clinical presentation is usually indistinguishable clinically from those of influenza and a variety of other common causes of fever. Unless the condition is diagnosed and treated promptly, a patient with P. falciparum malaria may deteriorate rapidly .
All travelers to areas with malaria risk are advised to use personal protective measures to prevent bites from Anopheles mosquitoes. Because of the nocturnal feeding habits of Anopheles mosquitoes, malaria transmission occurs primarily between dusk and dawn. Mosquito repellents containing DEET (N,N-diethyl-3-methylbenzamide) are especially useful for protection during outdoor activities. They should be applied to exposed skin surfaces and repeated after 4–6 h. Repellents should not be sprayed on the face nor applied to lips or eyelids, and the dosage should not be exceeded, especially for small children. Icaridin (picaridin) and P-menthane-3,8-diol (lemon eucalyptus oil) may be used as a second-line alternative repellent. If travelers are also wearing sunscreen, sunscreen should be applied first and insect repellent second. Combining DEET and permethrin-impregnated clothing enhances protection against biting arthropods. Insecticide-treated (permethrin) mosquito nets have been proven effective and are advised for all travelers visiting disease-endemic areas where they are at risk from biting arthropods while sleeping .
The decision as to whether chemoprophylaxis is necessary depends on the areas to be visited and the risk that the traveler has of being exposed to mosquitoes and of developing malaria. The greater the traveler’s risk of contracting malaria and developing complications, the greater the need for chemoprophylaxis. When deciding on the need for chemoprophylaxis, it must be remembered that all medicines have adverse effects and that the risk of developing a serious adverse effect must be weighed against the risk of developing malaria. Doxycycline, chloroquine, atovaquone-proguanil, or mefloquine can be used prophylactically. Mefloquine does lower the seizure threshold, and its side effects could potentially be confused with decompression or narcosis events. It should also be noted that some sub-aqua centers do not permit those taking mefloquine to dive. Mefloquine might therefore be better avoided for those undertaking diving holidays, but there is no contraindication to its use in occasional divers who have taken and tolerated the drug before, or those able to start taking it early to ensure that no adverse events occur. Dizziness is one of the side effects that have occurred in chemoprophylaxis studies. Doxycycline may cause photosensitivity which is mostly mild and transient. The prescriber should warn against excessive sun exposure (and advise on the correct use of a broad spectrum sunscreen) . No chemoprophylaxis is 100 % effective. However, disease in those taking chemoprophylaxis is likely to be milder or less rapidly progressive even if the parasites exhibit a degree of drug resistance. Chemoprophylaxis needs to be used in addition to, and not instead of, personal protection measures. The most reliable way of preventing malaria is to avoid mosquito bites.
Myiasis is the infestation of live humans and vertebrate animals by fly larvae. The risk of a traveler’s acquiring a screwworm infestation has been considered negligible, but with the increasing popularity of adventure sports and wildlife travel, this risk may need to be reassessed. One case was reported in a Finnish man, who was participating in an international adventure sports race in Pará (a jungle area in Brazilian Amazon), and tripped at night over a loose rock while he was riding a bicycle .
Myiasis occurs in tropical and subtropical areas. People typically get the infection when they travel to tropical areas in Africa and South America. People traveling with untreated and open wounds are more at risk for getting myiasis.
Even physicians unfamiliar with this condition can easily diagnose cases in which maggots are visible. On the other hand, furuncular, migratory, and cavitary cases and pseudomyiasis pose a diagnostic challenge, especially to those doctors unacquainted with myiasis and its possibilities . Fly larvae need to be surgically removed.
Preventing possible exposure is key advice for patients traveling in endemic areas. In regions of endemicity, sleeping nude, outdoors, and on the floor should be avoided. Appropriate precautions will help avoid infestations. The use of screens and mosquito nets is essential to prevent flies from reaching the skin. Some fly species infestation may be thwarted by the application of insect repellents containing DEET. Drying clothes in bright sunlight and ironing them are effective methods of destroying occult eggs laid in clothing. Other general precautions include wearing long-sleeved clothing and covering wounds .
Human schistosomiasis is a major health issue in many parts of Africa, Asia, and Latin America. It is estimated that 200 million people, in 76 countries, are infected with one of the schistosome species that cause the disease . Most infections worldwide are attributable to three species: Schistosoma mansoni, S. haematobium, and S. japonicum. Infection in humans comes from water contact, and transmission occurs via the penetration of larval cercariae in contaminated freshwater.
Schistosomiasis in travelers is well established, including outbreaks among athletes after freshwater exposure, mainly prolonged exposure, such as rafting or kayak competition [10, 11].
Many of the travelers, who have never been exposed to the disease, can develop its acute form. Acute schistosomiasis is a transient hypersensitivity syndrome that is caused by the juvenile forms of Schistosoma species. The clinical manifestations of this syndrome appear 2–8 weeks after exposure, and the common manifestations are fever, urticaria, malaise, cough, myalgia, and gastrointestinal complaints . As asymptomatic schistosomiasis in travelers is also common (43 % in one series) , all travelers exposed to freshwater in endemic areas should be encouraged to undergo screening tests.