The prevalence of Plasmodium falciparum parasitaemia was evaluated in
59 neonates admitted to the University College Hospital, Ibadan in Sou
th-western Nigeria between August and December 1991-a period spanning
part of both wet and dry seasons. Peripheral parasitaemia was present
in 14 (23.7%) neonates; of these, four were preterm (4/26, 15%) and te
n were term babies (10/33, 30.3%). The difference in the prevalence of
P. falciparum parasitaemia in the two groups was not statistically si
gnificant (chi2 = 1. 78; p = 0.10). Parasite densities in all neonates
were uniformly low (< 2000 asexual forms/mul blood), and only four of
the neonates had fever within 48 hrs of birth. Infected neonates weig
hed 200 g more than non-infected neonates, but the difference was not
statistically significant. Maternal weekly pyrimethamine prophylaxis d
id not appear to be effective in preventing infection as six (21.4%) o
f the 28 neonates whose mothers had regular prophylaxis had parasitaem
ia compared with seven (26.9%) of the 26 neonates whose mothers had no
prophylaxis (chi2 = 0.22; p > 0.05). These data indicate that congeni
tal malaria is not as uncommon as was previously thought and that the
recent increase in reported cases may be due to an interplay of severa
l factors.