Tuberculosis of the abdomen is common in Nepalese natives, but not tourists. It presents with fever, wasting, ascites, and intermittent diarrhea [ 18 ]. Fluid intake should be encouraged, and attention should be paid to potential electrolyte loss. Empiric treatment with a fluoroquinolone effective against most bacterial pathogens and an antimotility drug would be appropriate treatment for most cases of diarrhea and gastroenteritis in the tourist at high altitude [ 19 ]. Hepatitis A and E virus infections are common outside of developed countries. Hepatitis E is one of the most common causes of jaundice in the adult population of the Indian subcontinent [ 20 ].
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Before the introduction of the hepatitis A vaccine, many outdoor trekkers in the high Himalayas were stricken with this disease and suffered miserably. Japanese tourists to the Nepal Himalayas almost universally do not receive immunization and have an increased risk of hepatitis A [ 21 ]. Prevention of hepatitis A is achieved through hygienic practices and active immunization.
Efficacy trials of hepatitis E vaccine are ongoing in Nepal [ 22 ]. Rabies infection is a serious concern for those venturing into wild parts of Latin America, Africa, and Asia. Those going to high altitudes are at an increased risk because they cannot readily avoid rabid animals and cannot be treated quickly after exposure. Clinical knowledge of rabies prevention is paramount, and one should have a very low threshold for descent and evacuation for rabies immunoglobulin and postexposure immunization in the event of a dog or monkey bite in the mountains. Those considering long wilderness trips should be strongly encouraged to receive rabies immunization.
Japanese encephalitis JE is endemic in rural areas of Southeast Asia and parts of the Indian subcontinent. Although recent reports have identified JE as an emergent infection in the local population with no travel history outside of Kathmandu [ 23 ], no tourists to high altitude have been diagnosed, probably due to the rarity of the Culex mosquito vector at such altitudes. In the Indian subcontinent, JE must be differentiated from tuberculosis meningitis, bacterial meningitis, and typhoid encephalopathy, all seen in the local population.
Treatment is symptomatic. Prevention involves mosquito avoidance and vaccination. Tickborne encephalitis is endemic to central and eastern Europe, the former Russian states, and sporadically throughout the eastern Mediterranean. Because endemic areas include deciduous forest below the altitude of m, tickborne encephalitis and perhaps its Ixodes tick vector may be uncommon in sojourners to the Alps and Ural Mountains unless the disease was acquired at a lower altitude. Bacterial meningitis, although endemic in many developing country settings such as the Indian subcontinent, is uncommon in the traveler to high altitude.
However, it remains important to consider bacterial meningitis as a potential danger to the outdoor trekker in general. Respiratory problems are common at high altitude [ 10 , 24 , 25 ]. Symptoms are exacerbated by hypoxic conditions, crowding into tents and huts, smoky wood stoves, and cold, dry air [ 26 ]. Common manifestations include sinusitis, pharyngitis, bronchitis, and pneumonia. Sore throat and cough are common above m. Just like the ubiquitous Khumbu cough in the Nepal Himalayas, bronchitis in Aconcagua climbers was seen in 13 of 19 climbers at m [ 27 ]. The cough can be purulent or dry, and it can be severe enough to cause rib fractures.
Nasal congestion may worsen hypoxemia, especially at night when excessive oxygen desaturation is common during episodes of periodic breathing. Respiratory infections may predispose the outdoor trekker to acute mountain sickness [ 10 , 24 , 25 ]. In fact, if acute altitude sickness develops after a respiratory infection, further ascent up the mountain may need to be postponed because life-threatening high-altitude cerebral edema or pulmonary edema may result. The microbiological etiology, if any, of most respiratory illnesses remains unknown.
Nonspecific prevention of respiratory symptoms is important at higher altitudes; such prevention includes keeping the head warm, adequate hydration, use of nasal decongestants, and breathing through a silk scarf to keep air humidified [ 28 ]. Even with purulent sputum production, the role of antibiotics is not established [ 29 ].
The common symptoms of cough, tachycardia, tachypnea, and shortness of breath are shared by respiratory infections and by high-altitude pulmonary edema [ 2 ]. We maintain a low threshold for treatment with decent should either condition develop. However, antibiotics are often used. Before travel, influenza vaccine should be considered, particularly for those not immunized within the past year, who are visiting the tropics where influenza poses a year-round risk, who are part of a large travel group, or who are visiting the Southern Hemisphere during April through September [ 30 ].
In the local population of the developing world, the differential diagnosis of cough must include pulmonary tuberculosis. An increased incidence of chronic obstructive pulmonary disease and cor pulmonale occurs in the mountain population of the Indian subcontinent. The high incidence is thought to be secondary to chronic smoke inhalation in poorly ventilated, smoke-filled dwellings [ 31 ]. Pyoderma, carbuncles, furuncles, and wound infections are among the most common problems encountered among people sojourning to the mountains [ 32 ].
Poor hygiene, prolonged exposure to moisture, trauma, and frostbite are common in the mountain wilderness and predispose the outdoor trekker to frequent and severe dermatological problems. In the hypoxic high-altitude environment, wounds may heal slowly, despite therapy with antibiotics. Superficial infections can be accompanied by cellulitis and lymphangitis [ 33 ]. Descent to lower altitude may be the only definitive treatment. Exposure to ultraviolet radiation and frigid weather can reactivate herpes simplex infections.
Scabies and lice are endemic. In situations of trauma, burns, and surgical procedure at high altitude, impaired immunity and poor hygiene associated with altitude may result in a festering wound infection [ 28 ]. Local inhabitants commonly present with advanced cases of skin infections that afflict visitors, but less severely. For example, septicemia and osteomyelitis not uncommonly develop secondary to uncontrolled skin infections in natives. Suppurative otitis media may predispose local inhabitants to facial infection, bone infection, hearing loss, and meningitis.
Varicella is common in Nepalese children; visitors unsure of their immune status should consider varicella immunization before travel. Malaria is a pervasive danger. It may take weeks for Plasmodium falciparum and months for P. Diagnosis is presumptive, and medical evacuation from high altitude to a larger center is the norm. The mainstays of malaria prevention when visiting endemic areas are mosquito repellents and chemoprophylaxis.
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Like malaria, travelers are infected in the lowlands and become ill after reaching higher altitude. Diagnosis is presumptive. Treatment is generally supportive and includes descent. Prevention of mosquito bites should be stressed during pretravel counseling. Dengue hemorrhagic fever occurs in natives at lower altitudes and is rarely, if ever, seen in mountain travelers. Typhus is probably an underdiagnosed cause of fever in mountain travelers, although like most other infections at higher altitudes, the prevalence is anecdotal. Typhus is caused by Rickettsia prowazekii, R.
One individual treated with ciprofloxacin for diarrhea and fever while outdoor trekking did not improve and was subsequently diagnosed in Bangkok as having typhus; treatment with doxycycline resulted in rapid improvement unpublished data. The Phlebotomus sandfly is the vector for bartonellosis, caused by Bartonella bacilliformis, and occurs only in the Colombian, Ecuadorian, and Peruvian Andes at — m.
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Diagnosis is made by the clinical presentation in the presence of anemia and by visualization of the pathogen via erythrocyte smears. Bartonella infections are treated with tetracycline or chloramphenicol [ 39 ]. Leptospirosis is commonly spread by direct contact of abraded skin with contaminated water or soil. Mountain expeditions often require passage through water at base camp, thus offering potential exposure. Treatment involves therapy with doxycycline or ampicillin, depending on the severity of infection [ 40 ]. Pain at the location of dental caries may occur, possibly due to decreased atmospheric pressure with expansion of gas in the cavity at high altitude.
Sexually transmitted diseases, yeast infections, and urinary tract infections are common at sea level and at high altitude. Mountain sojourners who have increased their frequency of sexual activity, who have acquired new partners, who have started antibiotic therapy, or who are unable to maintain usual levels of personal hygiene are prone to sexually transmitted diseases. Gonorrhea, chlamydia, trichomonas, candidiasis, genital herpes, and acute HIV infection may result, among other infections.
Urinary tract infections can be diagnosed in the field via urine dipstick, but they are most often treated empirically. Descent is usually not necessary unless severe pain and fever suggest pyelonephritis. In essence, infections and infectious diseases at high altitude often parallel those in adjacent lowland environments. Immunomodulation, hypoxemia, hypobaria, physiological adaptation, harsh environmental stressors, exposure to foreign agents, and reckless behavior can enhance susceptibility to pathogens.
The ultimate treatment may require descent. Prevention is crucial; both counseling and immunization are essential table 2.
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Clearly, more research needs to be done on high-altitude infections to better understand their pathogenic mechanisms and epidemiology and to improve treatment and prevention. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.
Sign In or Create an Account. Sign In. Advanced Search. Article Navigation. Close mobile search navigation Article Navigation. Volume Article Contents. Gastrointestinal Infections. Hepatitis A And Hepatitis E. Neurological Infections. Respiratory Infections. Dermatological Infections. Insectborne Infections. In , more than million people visited altitudes that could lead to altitude illness. Adventurous travellers are not the only ones at risk; high-altitude cities are becoming popular tourist destinations for travellers of all ages and with varying severity of chronic illness.
bizttualminoremp.tk General practitioners GPs are still the most frequented source of information for travellers, and are well positioned to help empower travellers to care for themselves overseas. The management of altitude illness is not covered, as treatment is usually provided by expedition doctors or clinics at high altitude.
High altitude is used in this article to mean altitudes higher than m at which a traveller sleeps; significant altitude illness is unlikely below this height. As altitude increases, barometric pressure decreases and, consequently, the amount of oxygen in each breath decreases Figure 1. The body responds acclimatisation to low oxygen within minutes of the traveller arriving at a place of high altitude and this process continues for weeks. The important initial changes are:.
Individual and genetic variances exist in this acclimatisation response, 7 and inadequate responses lead to the pathological changes of altitude illness. Although the exact pathogenesis remains unclear, increased capillary leakage causing cerebral oedema in acute mountain sickness AMS and high-altitude cerebral oedema HACE , 8 and similar pulmonary changes in HAPE, 9 have been consistently described. The likely causes for this are hypoxia-induced blood flow and pressure increases, and capillary leakage mediated by chemicals such as bradykinin, nitric oxide, arachidonic acid and vascular endothelial growth factor.
Altitude illness is a collection of different conditions that occur at high altitude: high-altitude headaches HAH , AMS, HACE, HAPE and other less common conditions such as retinal haemorrhage, high-altitude syncope, cerebral venous thrombosis and cortical blindness. HAPE, also potentially fatal, can develop independently of the other conditions in places at high altitude.
HAH settles with oxygen after 10—15 minutes, and resolves with decrease in altitude and a non-steroidal anti-inflammatory drug NSAID such as ibuprofen mg three times a day Headache after a rise in altitude in the past four days, and at least one of the following symptoms: Presents within six to 36 hours of high-altitude exposure, is usually benign and commonly resolves in two to four days with simple rest and ceasing further rise in altitude.
Rapidly progressing, life-threatening marked elevation of intracranial pressure and cerebral oedema. Considered a progression from severe AMS, and is usually preceded by a further decrease in oxygenation in a person with severe AMS. Characterised by symptoms of severe AMS and cerebral symptoms, signs of impaired mental state, and the cardinal symptom and signs of ataxia. Occurs 0. People with HAPE report dyspnoea, cough, decreased exercise tolerance, or chest tightness, and exhibit signs of pulmonary oedema: pulmonary crepitations, tachypnoea, tachycardia or cyanosis.
Usually commences two to four days after arrival at a place of high altitude, Can develop independently of AMS. Urgent treatment by trained medical staff requires rapid descent of about m, oxygen, and nifedipine with adjunctive drugs. Because there is a lack of standardisation in altitude, ascent rate, outcome and populations, the reported prevalence of AMS varies in different studies.
The most important risk factors identified in the literature are how high and how quickly one ascends, and whether travellers previously developed altitude illness. This information is based on guidelines developed by the Wilderness Medical Society. Medications are a useful adjunct to prevent altitude illness in travellers who are not able to follow the recommendations for prevention, or who may have had altitude illness before Table 2. Headache, swollen ankles and constipation AMS-like symptoms Many significant interactions, especially with drugs that are metabolised via the cytochrome P 3A4 pathway.
Acetazolamide, commonly prescribed off-label in Australia to prevent AMS, is the only drug currently shown to facilitate acclimatisation. Acetazolamide decreases the resorption of bicarbonate in the proximal renal tubule and binds carbon dioxide in the peripheral tissues, resulting in metabolic acidosis.
By reducing the metabolic alkalosis of hypocapnia, which normally inhibits the central respiratory drive, hyperventilation can continue for longer. Acetazolamide also acts as a mild diuretic, decreasing oedema. An interesting side effect, not mentioned in Table 2, is decreased effervescence of carbonated beverages because of carbonic anhydrase inhibition in the saliva.
There is difficulty generalising from studies that use two different populations: climbers who are at places of high altitude and going higher, and general travellers who travel from sea level to lesser heights. However, a meta-analysis of 11 randomised control studies concluded that acetazolamide mg daily was strongly associated with a decrease in AMS combined odds ratio of 0. Multiple trials have shown dexamethasone to be of benefit in preventing AMS.
The key role of dexamethasone is in the treatment of altitude illness, with prevention being reserved for those who cannot tolerate acetazolamide.
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Budesonide also had fewer side effects than dexamethasone. Sumatriptan and gabapentin have single studies to support effectiveness, but further research needs to be conducted before these medications can be recommended as prophylaxis for AMS. Gingko biloba was claimed to have some benefits in preventing AMS; however, the research is inconsistent and conflicting on the association between gingko biloba and AMS.
Some have suggested coca tea, offered at hotels in Cusco, as a prevention against AMS; however, there are currently no systematic studies to support these claims. Anyone with a prior history of severe acute mountain sickness, or high-altitude cerebral oedema or pulmonary oedema. With no direct literature to consult, and individual variation and comorbidities, it is difficult to advise about the safety of travel to places at high altitude for people with pre-existing conditions. Generally, people with stable heart conditions, epilepsy and diabetes can safely travel up to m.
Relative contraindications include moderate COAD, stable angina, previous cerebrovascular disease, poorly controlled diabetes and recurrent arrhythmias. Risk for deep vein thrombosis is higher in places at high altitude and similar recommendations should be given as those for fitness for flying. Older people without any of the above-mentioned comorbidities have no increased risk of altitude illness. There is minimal information about the incidence of altitude illness in children. One study suggests a higher incidence; 33 however, most authorities agree that the incidence of altitude illness is similar to that in adults.
As clinicians, we are involved with the care of people who are increasingly entering the challenging environment of high altitude. This article provides scientific information for clinicians to assess the risk and provide information and interventions to prevent altitude illness as part of our role to facilitate a safe journey for our patients. To open click on the link, your computer or device will try and open the file using compatible software.
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