Risk Factors of Microbial Keratitis in Uganda: A Case Control Study

Abstract

Purpose: Microbial keratitis (MK), is a frequent cause of sight loss worldwide, particularly in low and middle-income countries. This study aimed to investigate the risk factors of MK in Uganda. Methods: Using a nested case control, we recruited healthy community controls for patients presenting with MK at the two main eye units in Southern Uganda between December 2016 and March 2018. Controls were individually matched for age, gender and village of the cases on a 1:1 ratio. We collected information on demographics, occupation, HIV and Diabetes Mellitus status. In STATA version 14.1, multivariable conditional logistic regression was used to generate odds ratios for risk factors of MK and a likelihood ratio test used to assess statistical significance of associations. Results: Two hundred and fifteen case-control pairs were enrolled. The HIV positive patients among the cases was 9% versus 1% among the controls, p = .0003. Diabetes 7% among the cases versus 1.4% among the controls, p = .012. Eye trauma was 29% versus 0% among the cases and controls. In the multivariable model adjusted for age, sex and village, HIV (OR 83.5, 95%CI 2.01-3456, p = .020), Diabetes (OR 9.38, 95% CI 1.48-59.3, p = .017) and a farming occupation (OR 2.60, 95%CI 1.21-5.57, p = .014) were associated with MK. Compared to a low socioeconomic status, a middle status was less likely to be associated with MK (OR 0.29, 95%CI 0.09-0.89, p < .0001). Conclusion: MK was associated with HIV, Diabetes, being poor and farming as the main occupation. More studies are needed to explore how these factors predispose to MK.

Mycotic Keratitis—A Global Threat from the Filamentous Fungi

“…It is thought that hyperglycaemia can alter the ocular surface microenvironment including changes to the commensal organisms and enzyme action, allowing easier fungal adherence, proliferation and corneal penetration [ 137 ]. The associated reduced immune response seen in diabetes is also likely to be a significant factor in increasing host susceptibility to fungal infection [ 138 ].…”

“…Another study from Tanzania a few years later found the prevalence of HIV infection amongst MK cases to be double that of the wider population [ 1 ], although this did not directly compare the proportion of HIV positive fungal MK cases to bacterial MK cases. A more recent, nested case control study from Uganda where over 60% of MK cases were fungal, found a strong association between HIV infection and MK (OR 83.5, p = 0.02) [ 138 , 142 ]. There have been no studies to date looking at this association outside of SSA.…”

“…Most TEM contain non-sterile preparations comprising plant matter, often herbs or dried leaves, and are therefore a potential route for inoculating the cornea with microorganisms, particularly fungal pathogens [ 60 ]. Although there are no studies that have specifically looked at TEM as a risk factor for fungal keratitis, it has been found to be an independent risk factor in developing microbial keratitis in Tanzania and Uganda [ 20 , 138 , 142 ], where a fungal aetiology make up the majority of MK cases.…”

“…In response, current and future work is focused on addressing these areas. Research projects are underway to improve the understanding of patients’ health-seeking behaviour, such as that recently completed in Uganda [ 18 , 138 , 142 ]. Linked to this is implementation research into primary preventative measures, specifically how to prevent ocular injuries from occurring in the first place.…”

BCLA CLEAR - Evidence-based contact lens practice

“…Certain ocular sequelae of diabetes are relevant to contact lens wear, including the presence of ocular surface disease, recurrent corneal erosions or reduced corneal sensitivity; however, providing these contraindications are absent, a patient with diabetes can still achieve successful contact lens wear [82]. Similar considerations apply to patients diagnosed with the human immunodeficiency virus (HIV) which can make them more susceptible to infection along with a number of potentially associated ocular pathologies [83]. In addition, they have a higher rate of meibomian gland drop-out [84].…”