Similarly, consultation biases may exist as the military population have medical consultation patterns that differ from the general population. We re-emphasize that diagnostic tools should be developed in the setting where they are used. Other potential biases include presentation biases from cases which rejected recruitment, presentations after recruitment hours which were not included, and losses to follow-up. Recall biases may exist as we obtained final clinical history two weeks after enrolment into the study, which we felt struck a balance between the risk of recall bias and the desire to capture comprehensively all symptoms during the illness period. Different diagnostic scores may need to be developed to account for local FRI aetiologies and socio-cultural-demographic differ- ences, but so doing will rely on well-designed local surveillance programs. The best clinical GW2580 syndrome to be used for surveillance is a potentially interesting question that may be explored by further related studies. Use of a predictive equation as a clinical diagnostic model can help better predict influenza than the conventional influenza-like illness definition among young adult military personnel with febrile respiratory illnesses. Until cheap, rapid and reliable point-of-care tests become widely available, clinical scores derived from large cohort studies may be of reasonable clinical utility. Among the different advantages commonly linked to an increase in body size, a widespread concept is that of an increasing digestive efficiency in larger herbivores. Based on the observation that energetic requirements of animals scale to metabolic body mass but gut capacity scales linearly with body mass in mammalian herbivores, Bell and Jarman deducted that at larger M, more gut capacity was available per unit energy requirement/food intake. This so-called ‘Jarman-Bell principle’ Guanidine hydrochloride was further refined subsequently and has found widespread application in ecology. This attractive concept provides an intuitive reason for the observation that larger-bodied herbivores usually ingest food of lower nutritional quality. However, recent findings do not support the notion that digestibility or ingesta retention increase systematically with body mass in mammals, and also not in herbivorous reptiles. Among potential disadvantages, ingesta particle size – one of the factors influencing digestive efficiency – increases with body mass, and it has been suggested that energetic losses due to methane production are also higher in larger animals. Methane production has been mainly measured in domestic herbivores to address the issue of feed energy use or, more recently, methane mitigation to reduce greenhouse gas emissions. Studies on methane production of non-domestic species have mainly been to complete national or global methane budgets. In contrast, comparative investigations on methane production with respect to herbivore physiology are rare. Methane production has been demonstrated in faeces of captive specimens of nearly all herbivorous terrestrial herbivores, including reptiles, and methanogenes have been demonstrated by fluorescence micros- copy in land and marine iguanas. In vivo methane production has not been investigated in reptiles to our knowledge. Recently, Franz et al. presented data collections that suggest that methane production scales linearly with M in ruminant and nonruminant mammalian herbivores. The implication of this finding is that because food intake scales to M0.75, energetic losses due to methane increase per unit ingested food with increasing body size.