Discussions

The analysis of J-SPEED data from the West Japan Heavy Rain 2018 disaster reported by 85 EMTs revealed the characteristics of a total of 3,617 consultations with a majority of consultations (2,579; 71.3%) occurring between Day 5 and Day 12 of the EMT response. During the response period, skin diseases were the most frequently reported health event, followed by wounds, disaster stress-related symptoms, conjunctivitis, and ARIs.

In the field of emergency medical response and natural disasters, the existing literature uses data and information collected from a variety of sources, including local hospital records, interviews with victims, routine death certificates, emergency clinical data, and other retrospective surveys. ^{Reference Levy, Woster, Goldstein and Carlton11} The J-SPEED data used in this study were collected in real time by operating EMTs during the disaster response, which is very unique for this study. In other words, the current study’s findings are highly context dependent.

In addition, health impacts of a natural disaster depend not only on the type and scale of the disaster, but also on a variety of factors such as geography and weather conditions, patterns of exposure, community infrastructure including hygiene setting, emergency preparedness, underlying vulnerability, and culture of the population.

This analysis includes the available global evidence while taking Japan-specific characteristics into account. The results can in turn identify good practice and lessons learned not only for Japan, but for other countries as well.

In the current analysis, it was discovered that skin diseases accounted for nearly one-third of all consultations. This is consistent with previous studies which found that inflammatory skin diseases, skin infections, traumatic skin diseases, insect bite reactions, and psycho-emotional aggravated primary skin diseases were common problems during floods. ^{Reference Lin, Lin, Guo and Chen12,Reference Bandino, Hang and Norton13} Although the J-SPEED data don’t allow to specify the exact type of skin diseases, it can still be suggested that skin disease is a common health problem not only in developing countries, but also in developed countries during heavy rain disasters. The current findings also revealed that skin disease is most common among children aged 0-8 years. Some literature reported no significant association between age and skin problems, ^{Reference Thongtaeparak, Pratchyapruit and Kotanivong14} while others found that older patients were more likely to have skin diseases than younger adults. ^{Reference Huang, Wang, Wu, Chen and Huang15} Thus, a consensus for this issue could not be found. There was a contextual episode identified regarding skin disease and conjunctivitis during the West Japan Heavy Rain. Following an increase in the number of reports of skin disorders and conjunctivitis, dermatologists and ophthalmologists participated in EMT services in the field and diagnosed the majority of those cases as caused by lime sprayed for disinfection. As a result, the EMTCC, in collaboration with local public health authorities, advised the public to wear appropriate protective gear to protect their skin and eyes.

Wounds and heat stroke were more common among those aged 9 to 74 years in this disaster response. Previous studies noted high incidence of wound due to flood, ^{Reference Schnitzler, Benzler, Altmann, Mucke and Krause16} however, the reasons for wounds vary, such as collapse of buildings or other structures or fast-moving water containing debris. ^{Reference Schnitzler, Benzler, Altmann, Mucke and Krause16} Garbern, et al ^{Reference Garbern, Ebbeling and Bartels17} revealed in their review study that heat-related problems are common during disaster in a hot environment. In the case of West Japan Heavy Rain, adults were heavily engaged in outdoor activities such as cleaning debris and reconstructing housing in an extremely hot environment. This context may help to explain the increased number of injuries and heat strokes among the adults during the mid-phase of the response. Heat acclimatization among the evacuees and the installation of spot coolers in shelters may be attributed to the decrease in number and proportion of heat strokes during the latter phase. Avoidable environmental problems, such as heatstroke, need to be well-managed through preventable measures, and during the West Japan Heavy Rain response, the EMTCC continuously announced preventable measures for heat stroke based on the number of cases reported during the response. Previous research has shown that children and elderly are particularly vulnerable to adverse physical consequences during floods; ^{Reference Hilmert, Kvasnicka-Gates, Teoh, Bresin and Fiebiger18} however, it was discovered that the working-age population was more vulnerable to most of the reported diseases, with the exception of blood pressure and thrombosis. As previously stated, this could be attributed to their active participation in some activities such as cleaning home during or after disaster.

It was found that ARIs were one of the most common problems among people of all ages. This is consistent with other studies that found ARIs to be the most common type of infectious disease among both developed ^{Reference Diaz1,Reference Carroll, Balogh, Morbey and Araoz19} and developing countries. ^{Reference Ligon20} In the current context, elders and children who stayed in shelters may have been affected by crowding which may have increased ARIs.

Unlike ARI, diarrheal diseases accounted for only 1.6% of total consultations in the current study. It is evident that the risk of gastrointestinal infection after flooding is highest, especially in developing countries, in areas with compromised hygiene practices, an inadequate supply of clean drinking water, unavailability of clean water for washing, inaccessibility of toilet, ^{Reference Noji, Crook and Auerbach21} and over-crowding. ^{Reference Wakuma Abaya, Mandere and Ewald22,Reference Stephens, Grew and Chin23} Some local practices such as fecal sludge application in agricultural communities, ^{Reference Seidu, Stenström and Löfman24} the conditions to promote the bacterial transmission via fecal-oral route by ingestion of contaminated food or water in developing countries, ^{Reference Biswas, Pal and Mukhopadhyay25,Reference Brandt, Brown and Burkhart26} are reported to be the contributing factors to the water-borne diseases during floods. The risk of outbreaks of diarrheal diseases is reported as low in high-income countries, however, it increases if the integrity of sewerage systems is compromised or unhygienic conditions arise. ^{Reference Murray, Kilborn and DesVignes-Kendrick27,Reference Yee, Palacio and Atmar28} Japan is known for having a high standard of cleanliness and hygiene and local governments provided sufficient amounts of clean drinking water during the disaster. In addition, the recovery time for disrupted water supply was relatively short. For example, during the Great East Japan Earthquake of 2011, the most tragic disaster in Japanese history, the median time of service recovery was three days. ^{Reference Matsumura, Osaki and Kudo29} Therefore, the low incidence of water-borne diseases during disaster in Japan may have been due to a high standard of hygiene, availability of drinking water supplies, and good personal hygiene.

Disaster-related stress symptoms were another major health problem. This is in line with innumerable studies that have found that disasters greatly increase susceptibility not only to physical illness, but also to poor mental health. ^{Reference Phifer, Kaniasty and Norris30–Reference Dai, Kaminga and Tan33} The current study showed that the incidence rate of stress was high during the early days and peaked in the later days. Stress may have derived from the panic caused by the sudden onset of events in the early days, as well as physical health issues, personnel losses, and economic hardship in the later days. The EMTs should be aware of physical conditions, socioeconomic status, and any other triggering factors throughout the response period.

Exacerbation of chronic diseases is one of the most common reasons for presenting to emergency facilities during ^{Reference Alderman, Turner and Tong34} natural disasters. The EMT received 150 patients (4.6% of total consultation; Table 2), with more than one-half being elderly people, with their treatment interrupted. Therefore, treatment disruptions may have contributed to exacerbation of chronic conditions in the elderly. Treatment disruption may occur as a result of flood damage to health facilities or inaccessibility to health facilities during heavy rain as has been seen in flooding even in developed countries. ^{Reference Schatz35} Thus, in light of the growing aged populations, it is critical to ensure that patients with chronic conditions are monitored and their medication is maintained during floods. ^{Reference Du, FitzGerald, Clark and Hou36}

Non-disaster-related events accounted for 10% of total consultations, with elders accounting for more than one-half of them. Distinguishing between disaster-related and non-related events is not a simple task, and for the J-SPEED reporting, judgment is left to the medical doctors of EMTs examining patients. Based on this practical reporting, it was discovered that non-disaster-related events increased as time passed after the disaster. During the response, the transition of this characteristic was used as an indicator to guide and support the EMTCC’s decision to demobilize the EMTs.