Prevention of common travel ailments

Inner Ear Arginine Vasopressin-Vasopressin Receptor 2-Aquaporin 2 Signaling Pathway Is Involved in the Induction of Motion Sickness

It has been identified that arginine vasopressin (AVP), vasopressin receptor 2(V2R), and the aquaporin 2 (AQP2) signaling pathway in the inner ear play important roles in hearing and balance functions through regulating the endolymph equilibrium; however, the contributions of this signaling pathway to the development of motion sickness are unclear. The present study was designed to investigate whether the activation of the AVP-V2R-AQP2 signaling pathway in the inner ear is involved in the induction of motion sickness and whether mozavaptan, a V2R antagonist, could reduce motion sickness. We found that both rotatory stimulus and intraperitoneal AVP injection induced conditioned taste aversion (a confirmed behavioral index for motion sickness) in rats and activated the AVP-V2R-AQP2 signaling pathway with a responsive V2R downregulation in the inner ears, and AVP perfusion in cultured epithelial cells from rat endolymphatic sacs induced similar changes in this pathway signaling. Vestibular training, V2R antagonist mozavaptan, or PKA inhibitor H89 blunted these changes in the V2R-AQP2 pathway signaling while reducing rotatory stimulus- or DDAVP (a V2R agonist)-induced motion sickness in rats and dogs. Therefore, our results suggest that activation of the inner ear AVP-V2R-AQP2 signaling pathway is potentially involved in the development of motion sickness; thus, mozavaptan targeting AVP V2Rs in the inner ear may provide us with a new application option to reduce motion sickness. SIGNIFICANCE STATEMENT: Motion sickness affects many people traveling or working. In the present study our results showed that activation of the inner ear arginine vasopressin-vaspopressin receptor 2 (V2R)-aquaporin 2 signaling pathway was potentially involved in the development of motion sickness and that blocking V2R with mozavaptan, a V2R antagonist, was much more effective in reducing motion sickness in both rat and dog; therefore, we demonstrated a new mechanism to underlie motion sickness and a new candidate drug to reduce motion sickness.

Occupational health of miners at altitude: adverse health effects, toxic exposures, pre-placement screening, acclimatization, and worker surveillance

CONTEXT

Mining operations conducted at high altitudes provide health challenges for workers as well as for medical personnel.

OBJECTIVE

To review the literature regarding adverse health effects and toxic exposures that may be associated with mining operations conducted at altitude and to discuss pre-placement screening, acclimatization issues, and on-site surveillance strategies.

METHODS

We used the Ovid ( http://ovidsp.tx.ovid.com ) search engine to conduct a MEDLINE search for "coal mining" or "mining" and "altitude sickness" or "altitude" and a second MEDLINE search for "occupational diseases" and "altitude sickness" or "altitude." The search identified 97 articles of which 76 were relevant. In addition, the references of these 76 articles were manually reviewed for relevant articles. CARDIOVASCULAR EFFECTS: High altitude is associated with increased sympathetic tone that may result in elevated blood pressure, particularly in workers with pre-existing hypertension. Workers with a history of coronary artery disease experience ischemia at lower work rates at high altitude, while those with a history of congestive heart failure have decreased exercise tolerance at high altitude as compared to healthy controls and are at higher risk of suffering an exacerbation of their heart failure. PULMONARY EFFECTS: High altitude is associated with various adverse pulmonary effects, including high-altitude pulmonary edema, pulmonary hypertension, subacute mountain sickness, and chronic mountain sickness. Mining at altitude has been reported to accelerate silicosis and other pneumoconioses. Miners with pre-existing pneumoconioses may experience an exacerbation of their condition at altitude. Persons traveling to high altitude have a higher incidence of Cheyne-Stokes respiration while sleeping than do persons native to high altitude. Obesity increases the risk of pulmonary hypertension, acute mountain sickness, and sleep-disordered breathing. NEUROLOGICAL EFFECTS: The most common adverse neurological effect of high altitude is acute mountain sickness, while the most severe adverse neurological effect is high-altitude cerebral edema. Poor sleep quality and sleep-disordered breathing may contribute to daytime sleepiness and impaired cognitive performance that could potentially result in workplace injuries, particularly in miners who are already at increased risk of suffering unintentional workplace injuries. OPHTHALMOLOGICAL EFFECTS: Adverse ophthalmological effects include increased exposure to ultraviolet light and xerophthalmia, which may be further exacerbated by occupational dust exposure. RENAL EFFECTS: High altitude is associated with a protective effect in patients with renal disease, although it is unknown how this would affect miners with a history of chronic renal disease from exposure to silica and other renal toxicants. HEMATOLOGICAL EFFECTS: Advanced age increases the risk of erythrocytosis and chronic mountain sickness in miners. Thrombotic and thromboembolic events are also more common at high altitude. MUSCULOSKELETAL EFFECTS: Miners are at increased risk for low back pain due to occupational factors, and the easy fatigue at altitude has been reported to further predispose workers to this disorder. TOXIC EXPOSURES: Diesel emissions at altitude contain more carbon monoxide due to increased incomplete combustion of fuel. In addition, a given partial pressure of carbon monoxide at altitude will result in a larger percentage of carboxyhemoglobin at altitude. Miners with a diagnosis of chronic obstructive pulmonary disease may be at higher risk for morbidity from exposure to diesel exhaust at altitude.

CONCLUSIONS

Both mining and work at altitude have independently been associated with a number of adverse health effects, although the combined effect of mining activities and high altitude has not been adequately studied. Careful selection of workers, appropriate acclimatization, and limited on-site surveillance can help control most health risks. Further research is necessary to more completely understand the risks of mining at altitude and delineate what characteristics of potential employees put them at risk for altitude-related morbidity or mortality.

Causes of death abroad: analysis of data on bodies returned for cremation to Scotland

BACKGROUND

The majority of travelers from the UK and Scotland visit Europe, particularly Spain and France, as well as North America, yet surveillance that aids in travel medicine guidance continues to focus on infectious diseases relating to developing countries. Here, we report on causes of death among all bodies returned to Scotland for cremation.

METHODS

Data collected by the Scottish Government on bodies being returned from abroad for cremation was collated for the period 2000 to 2004, and analyzed to identify the cause and location of death among travelers as well as to test the hypothesis that for death due to failure of the circulatory system among Scots there was a significant association between age at death and whether death occurred in Scotland or abroad.

RESULTS

Of the 572 deaths reported between 2000 and 2004, 73% occurred in the European region and 10% in the Americas. With respect to the cause, trauma accounted for 20.4%, infectious diseases 1.5%, and other non-infectious causes accounted for 75.5% of deaths. Among the latter, the major cause of death was due to failure of the circulatory system (77.0%). A significant association was observed between death abroad due to failure of the circulatory system and younger age at death for all (χ(2) = 26.9, df = 3, p < 0.001) and for males (χ(2) = 20.7, df = 3, p < 0.001) but not for females (χ(2) = 2.7, df = 1, p = 0.099).

CONCLUSIONS

The data indicates a low rate of death among Scots traveling abroad, with trauma and other non-infectious causes being the most common cause of death; failure of the circulatory system was the most common cause of death in the latter group. Europe and the Americas were the most common locations of death. Although travel health services should continue to advise travelers to developing countries on infectious disease risks, it is also important that travel health acts as venue for providing key advice and preventative means to all travelers, including those to developed countries. Those agencies, organizations, and companies who deal with travelers along their journey should also engage with travel health experts and practitioners to reduce the risk of adverse outcomes, including death, to travelers.

Prospective analysis of parasitic infections in Canadian travelers and immigrants

BACKGROUND

International travel is associated with increased risk of vector-borne illnesses, particularly malaria. The objective of this study was to prospectively assess the relative frequency of parasitic diseases in Canadian travelers and to characterize demographic and travel-related predictors of these infections.

METHODS

Data on Canadians and new immigrants who crossed international borders and were seen in the Tropical Disease Unit of Toronto General Hospital between November 1997 and June 2003 were prospectively collected and entered into the GeoSentinel Surveillance Network database.

RESULTS

Of 3,528 returned Canadian travelers and new immigrants in the database, 1,010 had a parasitic infection diagnosed. Mean age of the 3,528 travelers was 37.3 years, and 42.6% were male. Those diagnosed with parasitic infections were more likely than the remaining cohort to have been traveling for the purpose of immigration (21.1% vs 7.1%, p < 0.001), or visiting friends and relatives (VFR) (17.9% vs 11.8%, p < 0.01). Common parasitic infections included nonhistolytica amebiasis (N= 209), malaria (N= 143), cutaneous larva migrans (N= 105), giardiasis (N= 74), and schistosomiasis (N= 48).

CONCLUSIONS

Parasitic infections occurred in 29% of Canadian travelers. New immigrants and VFRs are at increased risk for malaria, as well as protozoal and helminthic infections.

Pediatric emergencies on a US-based commercial airline

OBJECTIVES

The purpose of this investigation was to determine the incidence and character of pediatric emergencies on a US-based commercial airline and to evaluate current in-flight medical kits.

METHODS

In-flight consultations to a major US airline by a member of our staff are recorded in an institutional database. In this observational retrospective review, the database was queried for consultations for all passengers up to 18 years old between January 1, 1995, and December 31, 2002. Consultations were reviewed for type of emergency, use of the medical kit, and unscheduled landings.

RESULTS

Two hundred twenty-two pediatric consultations were identified, representing 1 pediatric call per 20,775 flights. The mean age of patients was 6.8 years. Fifty-three emergencies were preflight calls, and 169 were in-flight pediatric consultations. The most common in-flight consultations concerned infectious disease (45 calls, 27%), neurological (25 calls, 15%), and respiratory tract (22 calls, 13%) emergencies. The emergency medical kit was used for 60 emergencies. Nineteen consultations (11%) resulted in flight diversions (1/240,000 flights), most commonly because of in-flight neurological (9) and respiratory tract (5) emergencies. International flights had a higher incidence than domestic flights of consultations and diversions for pediatric emergencies.

CONCLUSIONS

The most common in-flight pediatric emergencies involved infectious diseases and neurological and respiratory tract problems. Emergency medical kits should be expanded to include pediatric medications.

Health risks to air travelers

With focused pretravel counseling and intervention, travelers can be prepared to avoid many risks of in-flight problems. Travel medicine practitioners can include appropriate guidance for in-flight health and safety in discussions during pretravel visits.

Cabin location and the likelihood of motion sickness in cruise ship passengers

BACKGROUND

The prevalence of motion sickness approaches 100% on rough seas. Some previous studies have reported a strong association between location on a ship and the risk of motion sickness, whereas other studies found no association. This study was undertaken to determine if there is a statistical association between the location of the passenger cabin on a ship and the risk of motion sickness in unadapted passengers.

METHODS

Data were collected on 260 passengers on an expedition ship traversing the Drake Passage between South America and Antarctica, during rough sea conditions. A standard scale was employed to record motion sickness severity.

RESULTS

The risk of motion sickness was found to be statistically associated with age and sex. However, no association was found with the location of the passenger cabin.

CONCLUSIONS

Previous research reporting a strong association of motion sickness and passenger location on a ship, studied passengers in the seated position. Passengers who are able to lie in a supine position are at considerably reduced risk of motion sickness. Expedition or cruise ships that provide ready access to berths, allow passengers to avoid the most nauseogenic positions. The location of the passenger cabin does not appear to be related to the likelihood of seasickness.

Motion sickness. How to help your patients avoid travel travail

Motion sickness is an exceedingly common disorder about which primary care physicians are likely to be consulted for advice and treatment. Appropriate management should be based on patient characteristics and the type and length of the exposure and should include general preventive recommendations and directed pharmacologic agents. Education for patients about the causes of motion sickness and how to prevent it can alleviate anxiety and enhance their enjoyment of travel and recreation.