BackgroundPlacental malaria (PM) causes adverse pregnancy outcomes in the mother and her foetus. It is difficult to study PM directly in humans due to ethical challenges. This study set out to bridge this gap by determining the outcome of PM in non-immune baboons in order to develop a non-human primate model for the disease.MethodsTen pregnant baboons were acquired late in their third trimester (day 150) and randomly grouped as seven infected and three non-infected. Another group of four nulligravidae (non-pregnant) infected was also included in the analysis of clinical outcome. Malaria infection was intravenously initiated by Plasmodium knowlesi blood-stage parasites through the femoral vein on 160th day of gestation (for pregnant baboons). Peripheral smear, placental smear, haematological samples, and histological samples were collected during the study period. Median values of clinical and haematological changes were analysed using Kruskal-Wallis and Dunn’s Multiple Comparison Test. Parasitaemia profiles were analysed using Mann Whitney U test. A Spearman’s rank correlation was run to determine the relationship between the different variables of severity scores. Probability values of P <0.05 were considered significant.ResultsLevels of white blood cells increased significantly in pregnant infected (34%) than in nulligravidae infected baboons (8%). Placental parasitaemia levels was on average 19-fold higher than peripheral parasitaemia in the same animal. Infiltration of parasitized erythrocytes and inflammatory cells were also observed in baboon placenta. Malaria parasite score increased with increase in total placental damage score (rs = 0.7650, P <0.05) and inflammatory score (rs = 0.8590, P <0.05). Although the sample size was small, absence of parasitized erythrocytes in cord blood and foetal placental region suggested lack of congenital malaria in non-immune baboons.ConclusionThis study has demonstrated accumulation of parasitized red blood cells and infiltration of inflammatory cells in the placental intravillous space (IVS) of baboons that are non-immune to malaria. This is a key feature of placental falciparum malaria in humans. This presents the baboon as a new model for the characterization of malaria during pregnancy.

BackgroundEfforts in search of lasting malaria vaccine have led to the development of transgenic rodent malaria parasites. As a result, wild type Plasmodium berghei ANKA (WTPbA) has recently been transformed to express mouse interferon gamma (mIFN-γ). The immunomodulatory effect of this transgenic parasite on WTPbA infection has been demonstrated. However, the protective immune responses after repeated immunization with soluble lysate of this parasite has not been investigated.MethodsSoluble lysate of transgenic PbA (TPbA) was prepared and concentration of IFN-γ in lysate determined by ELISA. Four groups of 20 BALB/c mice each (two treatment groups and two control groups) were setup. Treatment Groups 1 and 2 were primed (at day 0) with lysate of TPbA containing 75 pg/ml IFN-γ and live TPbA parasites respectively. Infection in Group 2 mice was cured with Coartem™ at 450 mg/kg for 3 days. At day 14 post-priming, both groups were boosted twice at day 14 and day 28 with lysate of TPbA containing 75 pg/ml IFN-γ and 35 pg/ml IFN-γ respectively. Blood and spleen samples were collected at day 0, day 14, day 21 and day 28 for preparation of serum and cell cultures respectively. Serum IgG and cytokines (TNF-α and IFN-γ) levels in culture supernatant were measred by ELISA.Survivorship and parasitemia were daily monitored for 21 days. Data were statistically analyzed using ANOVA student’s t test. A p value of <0.05 was considered significant.ResultsAt day 28 post-priming, IFN-γ production in Group 1 was tenfold higher than in RBC control group (p = 0.070) There was significant difference in IFN-γ production among the groups at day 28 (p < 0.0001). TNF-α production in Group 1 mice increased fourfold in Group 2 mice from day 14 to day 28 post-immunization (p = 0.0005). There was no significant effect on serum IgG production. Mice in treatment groups survived 5 to 4 days longer compared to non-immunized group.ConclusionThe study has demonstrated that, repeated immunization with soluble lysate of TPbA induces Th 1 response leading to increased IFN-γ and TNF-γ production.

Background Senna occidentalis (L.) Link has been used worldwide in traditional treatment of many diseases and conditions including snakebite. In Kenya, a decoction from the plant roots taken orally, is used as a cure for malaria. Several studies have demonstrated that extracts from the plant possess antiplasmodial activity, in vitro. However, the safety and curative potency of the plant root against established malaria infection is yet to be scientifically validated, in vivo. On the other hand, there are reports on variation in bioactivity of extracts obtained from this plant species, depending on the plant part used and place of origin among other factors. In this study, we demonstrated the antiplasmodial activity of Senna occidentalis roots extract in vitro, and in mice. Methods Methanol, ethyl acetate, chloroform, hexane and water extracts of S. occidentalis root were tested for in vitro antiplasmodial activity against Plasmodium falciparum, strain 3D7. Cytotoxicity of the most active solvent extracts was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the curative potency in Plasmodium berghei infected mice evaluated by Rane’s test. Results All of the solvent extracts tested in this study inhibited the propagation of P. falciparum, strain 3D7, in vitro, with polar extracts being more active than non-polar ones. Methanolic extracts had the highest activity (IC50 = 1.76) while hexane extract displayed the lowest activity (IC50 = 18.47). At the tested concentrations, methanolic and aqueous extracts exhibited high selectivity index against P. falciparum strain 3D7 (SI > 10) in the cytotoxicity assay. Further, the extracts significantly suppressed the propagation of P. berghei parasites (P < 0.05) in vivo and increased the survival time of the infected mice (P < 0.0001). Conclusions Senna occidentalis (L.) Link root extract inhibits the propagation of malaria parasites in vitro and in BALB/c mice.

Background: There is limited data on the resistance mechanisms of Diarrhoeagenic Escherichia coli (DEC) from our centre which prompted us to perform this study to determine the antimicrobial resistance pattern.Methods & Materials: DNA extracted from confirmed DEC strains (48) isolated between November 2014 to March 2015 from 120 diarrhoeal stool specimens collected from children less than 5 years from were cultured were subjected to PCR for the detection of antimicrobial resistance genes (gyrA, gyrB, parC, parE, qnrA, qnrB, qnrS, qnrC, qepA, aac(6 )-Ib, sulI, sulII, sulIII, dhfrI, aac(3)-IV, aadB, tetA, tetY, tetD, tetE, tetC, tetB, catI, blaCTX, blaTEM blaSHV, int1, int3, int2 and erm).Results: All (100%) the strains harboured the quinolone resistance gene gyrB, while, gyrA and parE were present in 93.7% each, parC in 85.4%, aac(6 )-Ib and qnrS in 41.6% each, qnrB in 34.7%, qnrC in 31.2%, qepA in 18.7% and qnrA in 12.5%. Genes which are responsible for resistance to aminoglycoside aac(3)-IV (14.5%), aadB (6.2%), sulfonamides (sulI) (77%), (sulII) (31.2%), (sulIII) (6.2%), trimethoprim (dhfrI) (50%) and tetracycline (tetA) (56.25%), (tetY) (20.8%), (tetD) (18.7%), (tetE) (18.7%), (tetC) (16.6%),(tetB) (8.3%), chloramphenicol (catI) (39.58%) and ␤ lactam (blaCTX) (64.5%), (blaTEM) (20.8%) and (blaSHV) (8.3%) were also widely distributed. Integrons were noted in 70.8% (int1), 33.3% (int3) and 31.2% (int2), while none harboured the macrolide resistance gene erm. Conclusion:A diverse pattern was observed with regards to antimicrobial resistance genes in DEC. This study also illustrates the importance of integrons in the epidemiology of antibiotic resistance in DEC strains in our setting.