Decreased susceptibility to placental malaria in anaemic women in an area with unstable malaria transmission in central Sudan.

The interaction between iron level, iron supplementation, and susceptibility to infection, including malaria, remains a concern. A cross-sectional study was conducted at Medani hospital in central Sudan to investigate the relationship between anaemia and placental malaria. Obstetrical history was obtained; haemoglobin levels were determined. Placental tissue was obtained and malaria histology classified as active, chronic, past or no malaria infection. Among 324 women investigated, 7 (2·2%), 4 (1·2%), and 44 (13·6%) of the placentae showed active, chronic and past infection on histology examination respectively, while 269 (83·0%) of them showed no infection. Anaemia (haemoglobin <11 g/dl) was less frequent in women with placental Plasmodium falciparum infection, 27/55 (49·1%) vs 174/269 (64·7%), P=0·02. Anaemia was associated with a decreased risk for placental malaria, and the odds ratio for placental malaria (in both primiparae and multiparae group) was 0·2, 95% CI: 0·1-0·6, P=0·002 and it was 0·2, 95% CI: 0·03-0·7; P=0·02 for primiparae group. Thus, there is a strong relationship between anaemia and the absence of placental malaria.