High levels of TNF-α were also shown in patients hospitalized with leptospirosis [14], and an association was found between high levels of circulating TNF-α and an increased risk of lung involvement, bleeding and death [15], but a follow-up study by this group suggested that a high ratio of TNF-α to IL-10 may be a marker of lower severity [16]. This evidence concerns the gene TNF and leptospirosis.