Environmental Factors Related to Fungal Wound Contamination after Combat Trauma in Afghanistan, 2009-2011

Abstract

During the recent war in Afghanistan (2001-2014), invasive fungal wound infections (IFIs) among US combat casualties were associated with risk factors related to the mechanism and pattern of injury. Although previous studies recognized that IFI patients primarily sustained injuries in southern Afghanistan, environmental data were not examined. We compared environmental conditions of this region with those of an area in eastern Afghanistan that was not associated with observed IFIs after injury. A larger proportion of personnel injured in the south (61%) grew mold from wound cultures than those injured in the east (20%). In a multivariable analysis, the southern location, characterized by lower elevation, warmer temperatures, and greater isothermality, was independently associated with mold contamination of wounds. These environmental characteristics, along with known risk factors related to injury characteristics, may be useful in modeling the risk for IFIs after traumatic injury in other regions.

Keywords: Afghanistan; Aspergillus species; fungi; military medicine; mold; mucormycosis; trauma; wound infection; zygomycosis.

Figure 1

Geographic distribution of 71 case-patients with invasive fungal wound infections and 101 matched control-patients. Afghanistan, 2009–2011. Inset shows a detailed view of southern Afghanistan region where most cases originated. The IFI case-patients are classified according to established definitions (13). A proven IFI is confirmed by angioinvasive fungal elements on histopathologic examination. A probable IFI had fungal elements identified on histopathologic examination without angioinvasion. A possible IFI had wound tissue grow mold; however, histopathologic features were either negative for fungal elements or a specimen was not sent for evaluation. In addition, to be identified as an IFI, the wound must demonstrate recurrent necrosis after at least 2 surgical débridements. Because injuries frequently occurred in close proximity, some points overlay other points.

Figure 2

Geographic distribution of military personnel with wounds contaminated by mold (n = 101) and control-patients (n = 66), Afghanistan, 2009–2011. Inset shows detail view of southern Afghanistan region where most cases originated. The mold contaminated group includes 7 patients for whom cultures did not show mold growth, but were diagnosed with invasive fungal wound infections (IFIs) on the basis of histopathologic examination. Five patients with injuries sustained outside the study regions were excluded from the analysis (including 1 patient with IFI), but remain visible on the map (i.e., 1 point in western region, 2 in the southernmost point of Helmand Province below the box indicating the southern analysis region, and 2 in Zabul Province between the southern and eastern regions). Because injuries frequently occurred in close proximity, some points overlay other points. The mold contamination points are on top on the overview map and on the bottom in the enlarged inset. Higher elevation is indicated by darker brown.

Figure 3

Geographic features of southern and eastern Afghanistan study zones, 2009–2011. Inset shows detail view of southern Afghanistan region where most cases originated. Because injuries frequently occurred in close proximity, some points overlay other points. The mold contamination points are on top.

Figure 4

Geographic distribution of specific molds isolated from wounds sustained by military personnel in Afghanistan, 2009–2011.

Figure 5

Results of ecologic niche modeling in Afghanistan, 2009–2011 (A), and projection of findings onto Iraq (B). Darker red indicates areas estimated to have higher probability of mold presence based on the environmental conditions of mold contamination locations in Afghanistan (green circles).