Environmental temperature and case fatality of patients with Ebola virus disease in Sierra Leone and Liberia, 2014–2015: a retrospective cohort study

Abstract

Objective: Fluid loss during Ebola virus disease (EVD) infections from gastrointestinal dysfunction leads to volume depletion. It is possible that high environmental temperatures may exacerbate volume depletion or interfere with the provision of medical care by providers in full personal protective equipment. We investigated the effect of environmental temperature on case fatality. Methods: The International Medical Corps (IMC) operated 5 Ebola Treatment Units (ETUs) in Liberia and Sierra Leone during the 2014–16 epidemic. Demographic and outcomes variables for 465 patients with EVD were sourced from a de-identified, quality-checked clinical database collected by IMC. Daily environmental temperature data for Liberia and Sierra Leone were collected from a publicly available database (Weather Underground). Mean daily environmental temperatures were averaged across each patient’s ETU stay and environmental temperature thresholds were determined. Multiple logistic regression was utilized, with forward variable selection and threshold for entry of p<0.1. Statistical significance was defined as p<0.05. The following variables were analyzed as potential confounders: age, sex, ETU, length of ETU operation, and date of treatment. Results: Case fatality was 57.6% among patients diagnosed with EVD. Analysis of case fatality across environmental temperature quintiles indicated a threshold effect; the optimal threshold for average environmental temperature during a patient’s ETU stay was determined empirically to be 27.4°C (81.3°F). Case fatality was significantly greater for patients with average environmental temperatures above the threshold (70.4%) versus below (52.0%) (p<0.001). In multiple regression, patients with average environmental temperature above the threshold during their ETU stay were significantly more likely to die than patients below the threshold (aOR=2.5, 95% CI 1.6–3.8, p<0.001). This trend was observed only among patients treated in white tent ETUs, and not in ETUs with aluminum roofs. Discussion: These findings suggest that an average environmental temperature above 27.4°C (81.3°F) during patients’ ETU stay is associated with greater risk of death among patients with EVD. Further studies should investigate this effect. These results have potential implications for reducing case fatality through improved ETU construction or other temperature control methods within ETUs during future outbreaks.

Persistence of Bacteriophage Phi 6 on Porous and Nonporous Surfaces and the Potential for Its Use as an Ebola Virus or Coronavirus Surrogate

“…The two temperature and humidity combinations applied in this study were upper and lower health care facility extremes. As related to EBOV and coronaviruses, the upper extreme might be found in a tropical setting without adequate air conditioning, as seen in Liberia and Sierra Leone during the 2014 to 2016 epidemic, which was 27.4°C (35). The lower extreme was chosen as a setting common in Western health care facilities.…”

Impacts of climate change on human health in humanitarian settings: Evidence gaps and future research needs

“…Patients treated in Ebola Treatment Units tents in Liberia and Sierra Leone during the 2014-2016 epidemic had higher odds of fatality if the average environmental temperature was above 27˚C during their stay than those below [50]. Large fluctuations in climate may increase the population of bats infected with Ebola increasing risk of spillover into human population [51].…”

Enterotoxigenic Escherichia coli Heat-Stable Toxin and Ebola Virus Delta Peptide: Similarities and Differences

“…Instead, gastrointestinal symptoms such as abdominal pain, nausea, vomiting, and diarrhea were more prominent in patients with EVD [77][78][79][80][81][82]. Diarrhea was associated with mortality in patients with EVD [77,[83][84][85]. Up to 83% of patients who succumbed to Ebola suffered from diarrhea [84,[86][87][88][89].…”