Comparison of Transcriptomic Changes in Survivors of Exertional Heat Illness with Malignant Hyperthermia Susceptible Patients.

Exertional heat illness (EHI) is an occupational health hazard for athletes and military personnel-characterised by the inability to thermoregulate during exercise. The ability to thermoregulate can be studied using a standardised heat tolerance test (HTT) developed by The Institute of Naval Medicine. In this study, we investigated whole blood gene expression (at baseline, 2 h post-HTT and 24 h post-HTT) in male subjects with either a history of EHI or known susceptibility to malignant hyperthermia (MHS): a pharmacogenetic condition with similar clinical phenotype. Compared to healthy controls at baseline, 291 genes were differentially expressed in the EHI cohort, with functional enrichment in inflammatory response genes (up to a four-fold increase). In contrast, the MHS cohort featured 1019 differentially expressed genes with significant down-regulation of genes associated with oxidative phosphorylation (OXPHOS). A number of differentially expressed genes in the inflammation and OXPHOS pathways overlapped between the EHI and MHS subjects, indicating a common underlying pathophysiology. Transcriptome profiles between subjects who passed and failed the HTT (based on whether they achieved a plateau in core temperature or not, respectively) were not discernable at baseline, and HTT was shown to elevate inflammatory response gene expression across all clinical phenotypes.

Procedure for assessing patients referred to the UK's military Heat Illness Clinic: a case series.

INTRODUCTION: The UK military operates a Heat Illness Clinic (HIC) to aid the return to exercise, training and occupational duty recommendations for individuals who have suffered exertional heat illness or heatstroke. This paper describes the process of assessment and reports representative data from n=22 patients referred to the HIC. METHOD: The assessment included clinical consultation, and measurement of maximal oxygen consumption (V̇O2max) and a heat tolerance test (HTT) conducted on a treadmill in an environmental chamber with an air temperature of 34°C and 44% relative humidity. Patients began the HTT wearing military clothing, carrying a rucksack (mass 15 kg) and walking at 60% V̇O2max, at 30 min the rucksack and jacket were removed and the T-shirt at 45 min, individuals continued walking for 60-90 min. Patients were considered heat tolerant if rectal temperature achieved a plateau. RESULTS: N=14 patients were heat tolerant on the first assessment and of the n=8 patients required to return for repeat assessment, five were heat tolerant on the second assessment and the remaining three on the third assessment. CONCLUSIONS: In conjunction with patient history and clinical evaluation, the HTT provides a physiological basis to assist with decisions concerning patient management and return to duty following an episode of heat illness.

Relative changes in brain and kidney biomarkers with Exertional Heat Illness during a cool weather marathon.

BACKGROUND: Medical personnel may find it challenging to distinguish severe Exertional Heat Illness (EHI), with attendant risks of organ-injury and longer-term sequalae, from lesser forms of incapacity associated with strenuous physical exertion. Early evidence for injury at point-of-incapacity could aid the development and application of targeted interventions to improve outcomes. We aimed to investigate whether biomarker surrogates for end-organ damage sampled at point-of-care (POC) could discriminate EHI versus successful marathon performance. METHODS: Eight runners diagnosed as EHI cases upon reception to medical treatment facilities and 30 successful finishers of the same cool weather marathon (ambient temperature 8 rising to 12 ºC) were recruited. Emerging clinical markers associated with injury affecting the brain (neuron specific enolase, NSE; S100 calcium-binding protein B, S100ß) and renal system (cystatin C, cysC; kidney-injury molecule-1, KIM-1; neutrophil gelatinase-associated lipocalin, NGAL), plus copeptin as a surrogate for fluid-regulatory stress, were sampled in blood upon marathon collapse/completion, as well as beforehand at rest (successful finishers only). RESULTS: Versus successful finishers, EHI showed significantly higher NSE (10.33 [6.37, 20.00] vs. 3.17 [2.71, 3.92] ug.L-1, P<0.0001), cysC (1.48 [1.10, 1.67] vs. 1.10 [0.95, 1.21] mg.L-1, P = 0.0092) and copeptin (339.4 [77.0, 943] vs. 18.7 [7.1, 67.9] pmol.L-1, P = 0.0050). Discrimination of EHI by ROC (Area-Under-the-Curve) showed performance that was outstanding for NSE (0.97, P<0.0001) and excellent for copeptin (AUC = 0.83, P = 0.0066). CONCLUSIONS: As novel biomarker candidates for EHI outcomes in cool-weather endurance exercise, early elevations in NSE and copeptin provided sufficient discrimination to suggest utility at point-of-incapacity. Further investigation is warranted in patients exposed to greater thermal insult, followed up over a more extended period.

Investigating the genetic susceptibility to exertional heat illness.

BACKGROUND: We aimed to identify rare (minor allele frequency ≤1%), potentially pathogenic non-synonymous variants in a well-characterised cohort with a clinical history of exertional heat illness (EHI) or exertional rhabdomyolysis (ER). The genetic link between malignant hyperthermia (MH) and EHI was investigated due to their phenotypic overlap. METHODS: The coding regions of 38 genes relating to skeletal muscle calcium homeostasis or exercise intolerance were sequenced in 64 patients (mostly military personnel) with a history of EHI, or ER and who were phenotyped using skeletal muscle in vitro contracture tests. We assessed the pathogenicity of variants using prevalence data, in silico analysis, phenotype and segregation evidence and by review of the literature. RESULTS: We found 51 non-polymorphic, potentially pathogenic variants in 20 genes in 38 patients. Our data indicate that RYR1 p.T3711M (previously shown to be likely pathogenic for MH susceptibility) and RYR1 p.I3253T are likely pathogenic for EHI. PYGM p.A193S was found in 3 patients with EHI, which is significantly greater than the control prevalence (p=0.000025). We report the second case of EHI in which a missense variant at CACNA1S p.R498 has been found. Combinations of rare variants in the same or different genes are implicated in EHI. CONCLUSION: We confirm a role of RYR1 in the heritability of EHI as well as ER but highlight the likely genetic heterogeneity of these complex conditions. We propose defects, or combinations of defects, in skeletal muscle calcium homeostasis, oxidative metabolism and membrane excitability are associated with EHI.

Prospective study of biomechanical risk factors for second and third metatarsal stress fractures in military recruits.

OBJECTIVES: This prospective study investigated anatomical and biomechanical risk factors for second and third metatarsal stress fractures in military recruits during training. DESIGN: Prospective cohort study. METHODS: Anatomical and biomechanical measures were taken for 1065 Royal Marines recruits at the start of training when injury-free. Data included passive range of ankle dorsi-flexion, dynamic peak ankle dorsi-flexion and plantar pressures during barefoot running. Separate univariate regression models were developed to identify differences between recruits who developed second (n=7) or third (n=14) metatarsal stress fracture and a cohort of recruits completing training with no injury (n=150) (p<0.05). A multinomial logistic regression model was developed to predict the risk of injury for the two sites compared with the no-injury group. Multinomial logistic regression results were back transformed from log scale and presented in Relative Risk Ratios (RRR) with 95% confidence intervals (CI). RESULTS: Lower dynamic arch index (high arch) (RRR: 0.75, CI: 0.63-0.89, p<0.01) and lower foot abduction (RRR: 0.87, CI: 0.80-0.96, p<0.01) were identified as increasing risk for second metatarsal stress fracture, while younger age (RRR: 0.78, CI: 0.61-0.99, p<0.05) and later peak pressure at the second metatarsal head area (RRR: 1.19, CI: 1.04-1.35, p<0.01) were identified as risk factors for third metatarsal stress fracture. CONCLUSIONS: For second metatarsal stress fracture, aspects of foot type have been identified as influencing injury risk. For third metatarsal stress fracture, a delayed forefoot loading increases injury risk. Identification of these different injury mechanisms can inform development of interventions for treatment and prevention.

Thermoregulation and markers of muscle breakdown in malignant hyperthermia susceptible volunteers during an acute heat tolerance test.

OBJECTIVES: The study was undertaken to compare the thermal and biochemical responses to a heat tolerance test (HTT) of malignant hyperthermia (MH) susceptible individuals, volunteers who have suffered heat illness (HI) and control volunteers. METHODS: Three groups of male volunteers (n=6 in each group) were recruited to the study: MHS - civilian volunteers previously diagnosed as MH susceptible; EHI - military volunteers with a history of exertional HI; CON - military volunteers with no history of HI or MH. For the HTT, volunteers walked on a treadmill at 60% maximal oxygen uptake in a hot environment. Measurements were made of core and skin temperatures, heat flow, whole body sweat rate and serum lactate, creatine kinase and myoglobin concentrations. RESULTS: There were no differences in deep body temperature, oxygen uptake or serum lactate and creatine kinase concentrations between the three groups. One MHS volunteer and two EHI volunteers failed to achieve thermal balance with rectal temperature continuing to rise throughout the test and reaching 39.5°C, the rectal temperatures of the other volunteers plateaued at a mean (SD) of 38.7 (0.4)°C demonstrating thermal tolerance on this test. Serum myoglobin concentration and the increase in serum myoglobin was higher in MHS than EHI and CON Post HHT (P<0.05). CONCLUSION: MH susceptibility does not always predispose an individual to heat intolerance during an acute HTT, but does appear to increase muscle breakdown. The inclusion of serum myoglobin measurements to a HTT may help to distinguish patients that are potentially MHS, and who otherwise demonstrate thermal tolerance.

A narrow bimalleolar width is a risk factor for ankle inversion injury in male military recruits: A prospective study.

BACKGROUND: Ankle inversion injuries are one of the most common and burdensome injuries in athletic populations. Research that prospectively identifies characteristics associated with this injury is lacking. This prospective study compared baseline anthropometric and biomechanical gait characteristics of military recruits who sustained an ankle inversion injury during training, with those who remained injury-free. METHODS: Bilateral plantar pressure and three-dimensional lower limb kinematics were recorded in 1065 male, injury-free military recruits, during barefoot running. Injuries that occurred during the 32-week recruit training programme were subsequently recorded. Data were compared between recruits who sustained an ankle inversion injury during training (n=27) and a sample (n=120) of those who completed training injury-free. A logistic regression analysis was used to identify risk factors for this injury. FINDINGS: A narrower bimalleolar width and an earlier peak pressure under the fifth metatarsal were predictors of ankle inversion injury. Those who sustained an ankle inversion injury also had a lower body mass, body mass index, and a smaller calf girth than those who completed training injury-free. INTERPRETATION: Anthropometric and dynamic gait characteristics have been identified that may predispose recruits to an ankle inversion injury during Royal Marine recruit training, allowing identification of recruits at higher risk at the start of training.

Four biomechanical and anthropometric measures predict tibial stress fracture: a prospective study of 1065 Royal Marines.

BACKGROUND: Tibial stress fractures (TSFs) cause a significant burden to Royal Marines recruits. No prospective running gait analyses have previously been performed in military settings. AIM: We aimed to identify biomechanical gait factors and anthropometric variables associated with increased risk of TSF. METHODS: 1065 Royal Marines recruits were assessed in week 2 of training. Bilateral plantar pressure and three-dimensional lower limb kinematics were obtained for barefoot running at 3.6 m/s, providing dynamic arch index, peak heel pressure and lower limb joint angles. Age, bimalleolar breadth, calf girth, passive hip internal/external range of motion and body mass index (BMI) were also recorded. 10 recruits who sustained a TSF during training were compared with 120 recruits who completed training injury-free using a binary logistic regression model to identify injury risk factors. RESULTS: 4 variables significantly (p<0.05) predicted increased risk of TSF (ORs and 95% CI): smaller bimalleolar width (0.73, 0.58 to 0.93), lower BMI (0.56, 0.33 to 0.95), greater peak heel pressure (1.25, 1.07 to 1.46) and lower range of tibial rotation (0.78, 0.63 to 0.96). SUMMARY: Reduced impact attenuation and ability to withstand load were implicated in tibial stress fracture risk.

Rebreather Unit to Prolong Underwater Survival Time.

INTRODUCTION: This study investigated whether the timing of activation affects the utility of an emergency underwater rebreather unit (RBU) when submerged in cold water. METHOD: On two successive occasions, 16 male UK Royal Marines were submerged in stirred water at 12.2°C for up to 78 s. The subjects were lowered (taking 18 s) into the water in a seated position and were instructed to take a large breath in, activate the unit, breath-hold for as long as possible, exhale into the unit, and breathe normally to and from the unit for the remainder of submersion. On one occasion the subjects were instructed to activate the RBU when the water reached chest height (Condition-1) and, on the other, prior to the feet entering the water (Condition-2). Measurements were made of the duration of breath-hold, rebreathing and submersion, exhaled oxygen and carbon dioxide concentrations, skin temperature, and heart rate. RESULTS: In 16 of the 32 submersions, the breath-hold was released before the subject became fully submerged and in 8 submersions the subject requested early withdrawal from the water. Mean (SD) breath-hold duration was 14.0 (13.8) s and the duration of rebreathing was 45.9 (21.9) s. The duration of breath-hold once completely submerged was longer in Condition-1 (9.1 s) than Condition-2 (4.1 s). CONCLUSIONS: The study indicates the RBU should be activated just before the mouth becomes submerged rather than before entering the water, and that the RBU will prolong underwater stay time, thereby increasing survival prospects. House CM, Shaw AM, Roiz de Sa DG. Rebreather unit to prolong underwater stay time, thereby increasing survival prospects.

Biomechanical characteristics of barefoot footstrike modalities.

Barefoot running has increased in popularity over recent years, with suggested injury risk and performance benefits. However, despite many anecdotal descriptions of barefoot running styles, there is insufficient evidence regarding the specific characteristics of barefoot running. The present study provided reference data for four footstrike modalities adopted across a large cohort of habitually shod male runners while running barefoot: heel strikers (HS), midfoot strikers (MS), forefoot strikers (FS) and a newly defined group, toe runners (TR - contact made only with the forefoot), compared with the three modalities previously reported. Plantar pressure analysis was used for the classification of footstrike modality, with clearly distinguishable pressure patterns for different modalities. In the present study, the distribution of footstrike types was similar to that previously observed in shod populations. The absence of differences in ground contact time and stride length suggest that potential performance benefits of a non-HS style are more likely to be a function of the act of running barefoot, rather than of footstrike type. Kinematic data for the knee and ankle indicate that FS and TR require a stiffer leg than HS or MS, while ankle moment and plantar pressure data suggest that a TR style may put greater strain on the plantar-flexors, Achilles tendon and metatarsal heads. TR style should therefore only be adopted with caution by recreational runners. These findings indicate the importance of considering footstrike modality in research investigating barefoot running, and support the use of four footstrike modalities to categorise running styles.

Shock-absorbing insoles reduce the incidence of lower limb overuse injuries sustained during Royal Marine training.

This study was undertaken to determine whether the incidence of lower limb overuse injuries (LLOIs) sustained during Royal Marine training could be reduced by issuing the recruits with shock-absorbing insoles (SAIs) to wear in their military boots. This was a retrospective longitudinal trial conducted in two phases. Injury data from 1,416 recruits issued with standard Saran insoles and 1,338 recruits issued with SAI were compared. The recruits in the two groups were of similar height, body mass, and aerobic fitness and followed the same training course. The incidence of LLOI sustained by the recruits was lower (p < 0.05) in the SAI Group (19.0%) compared to the Saran Insole Group (31.7%). The incidences of lower limb stress fractures, tibial periostitis, tenosynovitis of foot, achilles tendonopathy, other tendonopathy and anterior knee pain were lower (p < 0.05) in the SAI Group. Tibial stress fracture incidence was lower (p < 0.05) in the SAI Group but metatarsal and femoral stress fracture incidences were the same for the two insole groups. Thus, issuing SAIs to military recruits undertaking a sustained, arduous physical training program with a high incidence of LLOI would provide a beneficial reduction in the incidence of LLOI.

High medial plantar pressures during barefoot running are associated with increased risk of ankle inversion injury in Royal Marine recruits.

BACKGROUND: Ankle inversion injury is common in military populations but associated biomechanical risk factors are largely unknown. This prospective study examined the association between pressure and kinematic variables, and ankle inversion injury risk in Royal Marine (RM) recruits. It was hypothesised that a more medially concentrated pressure at the heel-off phase of stance, greater impulse and peak pressure at the first metatarsal head, greater peak rearfoot eversion angle and greater eversion excursion would be associated with ankle inversion injury. METHODS: Data from 145 male, injury-free RM recruits were recorded in week-2 of a 32-week military training programme. Each recruit completed five running trials at 3.6 ms(-1), along a 2m pressure plate. Kinematic data were simultaneously recorded. Injuries sustained during the training programme were prospectively recorded. FINDINGS: Data from eleven recruits who had suffered an ankle inversion injury during RM training were compared with 20 uninjured controls. The injury group displayed a higher (P<0.05) peak first metatarsal pressure, peak metatarsal impulse and more medially concentrated pressure at heel-off than control recruits. There were no differences in kinematic variables between groups. The injury group had a lower body mass than controls (P<0.05). INTERPRETATIONS: The findings from this study support existing literature, providing evidence that high medial concentration of vertical forces when running are associated with increased ankle inversion injury risk. This may be due to the lateral ankle ligaments being less accustomed to loading, resulting in relatively weak lateral ligaments, or ligaments less able to deal with fatigue than those of the control group.

The impact of a phase-change cooling vest on heat strain and the effect of different cooling pack melting temperatures.

Cooling vests (CV) are often used to reduce heat strain. CVs have traditionally used ice as the coolant, although other phase-change materials (PCM) that melt at warmer temperatures have been used in an attempt to enhance cooling by avoiding vasoconstriction, which supposedly occurs when ice CVs are used. This study assessed the effectiveness of four CVs that melted at 0, 10, 20 and 30 °C (CV0, CV10, CV20, and CV30) when worn by 10 male volunteers exercising and then recovering in 40 °C air whilst wearing fire-fighting clothing. When compared with a non-cooling control condition (CON), only the CV0 and CV10 vests provided cooling during exercise (40 and 29 W, respectively), whereas all CVs provided cooling during resting recovery (CV0 69 W, CV10 66 W, CV20 55 W and CV30 29 W) (P < 0.05). In all conditions, skin blood flow increased when exercising and reduced during recovery, but was lower in the CV0 and CV10 conditions compared with control during exercise (observed power 0.709) (P < 0.05), but not during resting recovery (observed power only 0.55). The participants preferred the CV10 to the CV0, which caused temporary erythema to underlying skin, although this resolved overnight after each occurrence. Consequently, a cooling vest melting at 10 °C would seem to be the most appropriate choice for cooling during combined work and rest periods, although possibly an ice-vest (CV0) may also be appropriate if more insulation was worn between the cooling packs and the skin than used in this study.

Viral and bacterial serology of six free-ranging bearded seals Erignathus barbatus.

Serum or heparinized plasma samples were obtained from 3 male (2 adult and 1 weaned calf) and 3 adult female free-ranging bearded seals Erignathus barbatus in May of 1994, 1995, or 1996. Blood samples were obtained from animals taken in subsistence hunts near St. Lawrence Island, Alaska and screened for antibodies to a suite of bacteria and viruses potentially pathogenic for pinnipeds and/or humans. No samples had detectable antibodies to Brucella spp., Phocine distemper virus, influenza A virus or caliciviruses (San Miguel sea lion virus strains 1, 2, and 4 to 13, vesicular exanthema of swine serotypes A48, B51, C52, D53, E54, F55, G55, H54, 155, J56, K54, 1934B, and Tillamook and Walrus calicivirus). One seal had a low titer of 100 to Leptospira interrogans serovar

User trial and insulation tests to determine whether shock-absorbing insoles are suitable for use by military recruits during training.

A user trial was undertaken to determine whether a shock-absorbing insole is suitable for military use. Two thicknesses of insole (3 mm and 6 mm) were studied and were issued to 38 Royal Marine recruits to wear in their military boots for weeks 12 to 30 of training. Biomechanical measurements showed that both thicknesses of insole significantly (p < 0.05) attenuated the peak pressures generated at heel strike and during forefoot loading when new (relative to a no-insole condition) and that this was well maintained after wear. This was supported by mechanical tests conducted on the insoles. It was concluded that the insoles are sufficiently durable for military use. The main user complaint was that water retention reduced the comfort of the insoles; however, insulation tests conducted with a foot manikin indicated that switching from the current-issue Saran insoles to the trial insoles would not increase the risk of recruits sustaining nonfreezing cold injuries to their feet.

Antibodies to canine distemper and phocine distemper viruses in polar bears from the Canadian arctic.

Serum samples collected from 200 polar bears (Ursus marititnus) from two populations in the Canadian arctic, the western Hudson Bay and Lancaster Sound populations, between 1989 and 1996, were tested for antibodies to canine distemper (CDV) and phocine distemper viruses (PDV) using virus neutralization. Antibodies to CDV and PDV were detected in 48 and six polar bears, respectively. All six bears that tested positive for PDV also tested positive for CDV; in only one case did the antibody titer for PDV exceed that of CDV. Differences in antibody prevalence to CDV were detected between populations and age classes but not sex or year of sampling.

Protective immunity in cattle vaccinated with a commercial scale, inactivated, bivalent vesicular stomatitis vaccine.

A commercially prepared oil-adjuvanted, inactivated vaccine containing antigens of vesicular stomatitis virus (VSV) serotypes New Jersey (NJ) and Indiana 1 (IND1) was administered to calves to determine its ability to induce protective immunity. Weekly serological studies were conducted. The 12 calves in Group I were vaccinated once and challenge inoculated with VSV New Jersey 28 days later. Two calves were fully protected and two were partially protected. The five calves in Group II were vaccinated twice 40 days apart and challenge inoculated on 14 days post-second vaccination (dp2v) with VSV Indiana 1. All animals were fully protected. The 14 calves in Group III were vaccinated twice 91 days apart and challenge inoculated on 91 dp2v with VSV Indiana 1. All animals were fully protected. All control calves in each group became clinically ill. Two calves inoculated with VSV Indiana 1 challenge virus on day 0 and 11 weeks later showed clinical disease after each inoculation. No virus was isolated from the blood of four acutely ill calves 48 h after challenge inoculation.

Biomechanical analysis of running in military boots with new and degraded insoles.

PURPOSE: The purpose of the present study was to investigate the influence of degradation using repeated impacts on the ability of different shock-absorbing insoles to reduce peak impact loading during running in military boots. METHODS: Four insole types were degraded mechanically to simulate typical running loads that occur during approximately 100 km of running. The influence of insole mechanical degradation on stiffness and impact-absorbing ability was assessed using standard test procedures. The ability of new and degraded insole samples to reduce peak impact loading during running was assessed by monitoring peak impact force and rate of loading. In addition, the influence of insoles on sagittal plane kinematics was quantified by measurement of hip, knee, and ankle joint flexion. RESULTS: Insole mechanical degradation resulted in an increase in mechanical stiffness and a decrease in ability to reduce mechanical impacts for all test insoles. Measurements taken during running indicated that only one insole type reduced peak impact loading when new, as indicated by a significant (P< 0.05) reduction in peak rate of loading. The ability of this insole type to reduce peak rate of loading during running was maintained after mechanical degradation. This insole was also found to significantly (P< 0.05) reduce peak ankle dorsiflexion. CONCLUSION: The present study identifies an insole type that reduces peak rate of loading during running both when new and when mechanically degraded. It is suggested that this indicates an insole that could potentially reduce the frequency of overuse injuries. Based on these results, this insole is recommended for use in the investigation of the practical use of insoles by military recruits, particularly for study of the influence on injury occurrence.

The influence of simulated wear upon the ability of insoles to reduce peak pressures during running when wearing military boots.

Mechanical degradation of three types of shock absorbing insoles equivalent to 100-130 km of running did not reduce their ability to attenuate the peak pressures generated during running when wearing military boots. Pressure measurements at the heel and forefoot were recorded with pressure measuring insoles placed in the boots of nine subjects. Two of the three insoles tested reduced the peak pressures (P<0.05) generated at the heel and forefoot relative to the no-insole (control) condition. The most effective insole reduced the peak pressures at the heel by 37% and at the forefoot by 24%.

Viral and bacterial serology of free-ranging Pacific walrus.

Serum or heparinized plasma samples were obtained between 1994 and 1996 from 20 male and 20 female adult free-ranging Pacific walrus (Odobenus rosmarus divergens) from St. Lawrence Island and Round Island, Alaska. Samples were screened for antibodies to some potentially pathogenic bacteria and viruses. No sample had detectable antibody to Brucella spp. Three of 40 (8%) had low antibody titers to Leptospira interrogans serovars. Phocine distemper virus antibodies were not detected. Serologic responses to one or more caliciviruses (San Miguel sea lion virus 12 or vesicular exanthema of swine serotypes E54, F55, G55, 1934B) were detected in 18% (seven of 40) walrus. Antibodies to one or more subtypes of influenza A virus (H10, N2, N3, N5, N6, N7) were detected in 21% (eight of 38). Periodic screening of free-ranging populations for exposure to infectious diseases has become an important component of bio-monitoring programs to facilitate understanding and detecting trends in marine mammal populations.