Association of helminth infections with increased gametocyte carriage during mild falciparum malaria in Thailand

The objective of this study was to determine whether pre-existing helminth infections could affect sexual forms of Plasmodium falciparum. A cross-sect ional case record study compared 120 mild P. falciparum malaria cases with patent gametocyte carriage and 187 without gametocytes for helminth exposur e. Relevant crude odds ratios and potential confounders were included in a logistic regression model. Helminth infections were associated with the pre sence of gametocytes with a crude odds ratio of 1.9 (95% confidence interva l = 1.1-3.3) (P = 0.01). A positive linear trend was observed between the o dds of having patent gametocytemia and the number of different helminth spe cies (P = 0.003). However, when adjusting for hemoglobin concentration the significance of the association between helminths and gametocytes disappear ed (P = 0.15). Pre-existing helminth infections may increase the severity o f malarial anemia and therefore increase the likelihood of carrying gametoc ytes. At a population level, helminth infections may thus have a significan t influence on malaria transmission.