Sequestered Plasmodium falciparum parasites in human infections: different genotype distribution in placental and the peripheral circulation

Abstract

Introduction: In regions highly endemic for malaria, the prevalence of placental malaria ranges from 30% to 60% and has been associated with increased risk of adverse infant outcomes, particularly in primigravidae The study was conducted on mothers after delivery to detect hidden Plasmodium falciparum parasite, merozoite surface protein (mspl) & (msp 2) by PCR technique.75 pregnant women were enrolled in the study; the mean age of them was 26.30 i 7.02. Sml of venous blood were collected from the mothers after delivery. Materials and methods: Approximately, Sml of venous and placental blood were obtained from 75 mothers afier delivery, attended Omdurman Matemity Hospital, which is one of the largest matemity hospitals in the capital Khartoum. The mean age of the mothers was 26.3i7.02.The study was conducted during the pen'od January to May 2009. Genomic DNA was extracted from peripheral and placental blood samples using modified phenol chlorofonn technique. The msp-1 allele (MAD20,) and msp-2 allele A1, A2, Bl and B2, P. falciparum primers were used for PCR. The PCR product was analyzed on 1.5% Agarose gel and visualized by gel documentation system after ethidium bromide staining. Results: The results revealed that the overall malaria detection rate in peripheral blood and placental blood using ICT was 10.7%. With the PCR (msp-l alleles) the detection rate of malaria in peripheral blood was found to be 9.3%, while in placental blood the same technique showed a detection rate of 10.7%. For PCR (msp-2 alleles), the detection rate of malaria in peripheral blood was 12%, while in placental blood the same technique showed detection rate of 2 1 .3% malaria. p The detection rate of the different combination of the positive and negative results in peripheral and placental blood by using msp-1 alleles revealed that the highest rate (84%) was reported among the peripheral negative & placental negative group while the lowest rate (4%) was reported among the peripheral positive and placental positive. The detection rate of the different combination of the positive and negative results in peripheral and placental blood by using msp-2 alleles revealed that the highest rate (72%) was reported among the peripheral negative & placental negative group while the lowest rate (5.3%) was reported among the peripheral positive and placental positive . When msp-1 and msp-2 alleles used in combined way for the detection of malaria parasite in peripheral and placental blood, they revealed that they were identical in 66.7% of examined samples, discordant in 10.7% of the samples, positive in peripheral blood and not in placental blood in 8% of the samples and positive in placental blood not in peripheral blood in 14.7% of the samples. Out of the 53 cases with no previous history of malaria when using the ICT, 14 were found negative for malaria and out of the 5 positive cases with previous history of malaria, 3 were found positive. For the msp-1 used in peripheral blood, out of 52 cases with no previous history of malaria, 16 were found positive for malaria and out of the 6 cases with previous history of malaria, 1 ease was found positive for malaria. For the msp-1 used in placental blood, out of the 51 cases with no previous history of malaria, 16 were found positive for malaria and out of the 7 cases with previous history of malaria, l case was found positive for malaria. For the msp-2 used in peripheral blood, out of 51 cases with no previous history of malaria, 15 were found positive for malaria and out of the 7 cases with previous history of malaria, 2 cases were found positive for malaria. For the msp-2 used in placental blood, out of 46 cases of no previous history of malaria, 13 were found positive for malaria and out of the ll cases with previous history of malaria, 4 cases were found positive for malaria. When using the msp-1 for peripheral blood, the result showed that the mean body weight among the negatives was 3.187 and it was 3.1833 among the positives. When using the msp-1 for placental blood the result showed that the mean body weight among the negatives was 3.1967 and it was 3.1000 among the positives. When using the msp-2 for peripheral blood the result showed that the mean body weight among the negatives was 3.1705 and it was 3.3286 among the positives. When using the msp-2 for placental blood the result showed that the mean body weight among the negative was 3.1786 and it was 3.1889 among the positives. Conclusion: In the vast majority of cases, some sequestered genotypes remain hidden, undetected in the peripheral circulation, indicating that analysis of peripheral parasites generates a partial picture of a P. falciparum infection. The cord blood must be collected from the umbilical cord to detected placental P. falciparum infection particularly in primigravidae