Sequential Plasmodium chabaudi and Plasmodium berghei infections provide a novel model of severe malarial anemia.

Lack of an adequate animal model of Plasmodium falciparum severe malarial anemia (SMA) has hampered the understanding of this highly lethal condition. We developed a model of SMA by infecting C57BL/6 mice with P. chabaudi followed after recovery by P. berghei infection. P. chabaudi/P. berghei-infected mice had an initial 9- to 10-day phase of relatively low parasitemia and severe anemia, followed by a second phase of hyperparasitemia, more profound anemia, reticulocytosis, and death 14 to 21 days after infection. P. chabaudi/P. berghei-infected animals had more intense splenic hematopoiesis, higher interleukin-10 (IL-10)/tumor necrosis factor alpha and IL-12/gamma interferon (IFN-γ) ratios, and higher antibody levels against P. berghei and P. chabaudi antigens than P. berghei-infected or P. chabaudi-recovered animals. Early treatment with chloroquine or artesunate did not prevent the anemia, suggesting that the bulk of red cell destruction was not due to the parasite. Red cells from P. chabaudi/P. berghei-infected animals had increased surface IgG and C3 by flow cytometry. However, C3(-/-) mice still developed anemia. Tracking of red cells labeled ex vivo and in vivo and analysis of frozen tissue sections by immunofluorescence microscopy showed that red cells from P. chabaudi/P. berghei-infected animals were removed at an accelerated rate in the liver by erythrophagocytosis. This model is practical and reproducible, and its similarities with P. falciparum SMA in humans makes it an appealing system with which to study the pathogenesis of this condition and explore potential immunomodulatory interventions.

Intestinal Parasite Infections and Associated Risk Factors among Pre-School Aged Children in Kibera Informal Settlement, Nairobi, Kenya.

Background: Infections with intestinal parasites are a major public health problem in children in developing countries like Kenya. School going children are considered at most risk and are included in school-based de-worming program. Less focus is given to pre-school children and information is scarce about intestinal parasitosis among this age group. In this study, we determined the prevalence and intensity of protozoa and helminth infections, and associated risk factors in an informal settlement. Methods: A community based cross-sectional study was conducted from October 2016 to January 2017 among 406 children aged 2-5 years in Kibera informal settlements in Nairobi County, Kenya. Structured interviewer-administered questionnaire was used to collect sociodemographic information and data on associated factors. Stool samples were examined microscopically using formal ether concentration, iodine wet mounting, modified Ziehl-Neelsen staining, and Kato-Katz methods. Multivariable logistic regression analysis was used to identify risk factors associated with intestinal parasites. Results: The overall prevalence of any helminth and protozoa infections was 13.1% 53/406) and 22.4% (91/406) respectively. The predominant parasites were Giardia lamblia (13.8%), Ascaris lumbricoides (11.3%), Entamoeba histolytica/dispar (9.4%), Trichuris trichiura (3.9%), Entamoeba coli (1.5%) and hookworm (0.2%). Prevalence of co-infection with any helminths or protozoan was 2.7%. About 10.8% (44/406) and 20.7% (84/406) children were infected with single species of helminth and protozoan parasites. All helminth infections were light, with a mean intensity of 592 egg per gram. Intensity of any protozoan infections was heavy 62.6% (57/406). Dirt floors in the household (aOR = 2.22, p = .046), dirty toilets (aOR = 2.33, p=.014), water from communal taps (aOR = 0.27, p=.019), parent's education level (aOR=0.27, p=.032) and parent's earning (aOR =3.34, p=.007) were factors significantly associated with intestinal parasites. Conclusion: The study found both helminth and protozoan parasites to be prevalent among pre-school aged children in Kibera. Intervention measures including education on the improvement of hygiene and health, socio-economic conditions, sanitation, and provision of safe drinking water could reduce the prevalence of these infections.

Evaluating Antiplasmodial and Antimalarial Activities of Soybean (Glycine max) Seed Extracts on P. falciparum Parasite Cultures and P. berghei-Infected Mice.

BACKGROUND: Plasmodium parasite resistance to artemisinin-based combination therapies (ACTs) calls for development of new, affordable, safe, and effective antimalarial drugs. Studies conducted previously on soybean extracts have established that they possess antimicrobial, anti-inflammatory, anticancerous, and antioxidant properties. The activity of such extracts on Plasmodium parasite resistance to artemisinin-based combination therapies (ACTs) calls for development of new, affordable, safe, and effective antimalarial drugs. Studies conducted previously on soybean extracts have established that they possess antimicrobial, anti-inflammatory, anticancerous, and antioxidant properties. The activity of such extracts on. OBJECTIVES: The aim of this study was to determine the antiplasmodial activity of soybean extracts using Plasmodium falciparum cultures, followed by an in vivo evaluation of safety and antimalarial activity of the extracts in Plasmodium berghei ANKA strain-infected mice. METHOD: Aqueous, methanol, and peptide extracts of soybean seeds were prepared. An in vitro evaluation of the extracts for antiplasmodial activity was carried out using two P. falciparum strains: D6, a chloroquine-sensitive Sierra Leone 1 strain and W2, a chloroquine-resistant Indochina 1 strain. Following the in vitro evaluation of the extracts for antiplasmodial activity was carried out using two in vivo evaluation of safety and antimalarial activity of the extracts in P. berghei ANKA strain. The two extracts were tested for their therapeutic potential (curative test). The peptide extract was further assessed to determine whether it could prevent the establishment of a P. berghei ANKA strain. The two extracts were tested for their therapeutic potential (curative test). The peptide extract was further assessed to determine whether it could prevent the establishment of a P. berghei ANKA strain. The two extracts were tested for their therapeutic potential (curative test). The peptide extract was further assessed to determine whether it could prevent the establishment of a. RESULTS: Peptide and methanol extracts showed good activity with IC50 of 19.97 ± 2.57 µg/ml and 10.14 ± 9.04 µg/ml and 10.14 ± 9.04 µg/ml and 10.14 ± 9.04 µg/ml and 10.14 ± 9.04 P < 0.001) in suppression with lower doses. CONCLUSION: The results show the presence of antimalarial properties in soybean extracts with higher curative activity when compared to the prophylactic activity. However, more research needs to be conducted on this plant to possibly establish lead compounds.

Safety, efficacy and acceptability of praziquantel in the treatment of Schistosoma haematobium in pre-school children of Kwale County, Kenya.

BACKGROUND: The recommended strategy for control of schistosomiasis is preventive chemotherapy with praziquantel (PZQ). Pre-school children (PSC) are excluded from population treatment programs. In high endemic areas, these children are also at risk, and require treatment with PZQ. The Government of Kenya initiated the National School-Based Deworming Programme (NSBDP) where PSC in Early Childhood Development Education (ECDE) Centers are only eligible for treatment with albendazole (ABZ) but not with PZQ. METHODOLOGY/PRINCIPAL FINDINGS: 400 PSC were enrolled, from 10 randomly selected ECDE Centers in Kwale County, Kenya where children were treated with crushed PZQ tablets mixed with orange juice, at a single dose of 40 mg/kg. Adverse events were assessed 24 hours post-treatment through questionnaires administered to the parents or guardians. Acceptability was determined by observing if the child spat and/ or vomited all or part of the PZQ dose immediately after treatment. Efficacy was assessed by examining urine samples for Schistosoma haematobium eggs in the 5 weeks post-treatment follow-up. Children testing negative for S. haematobium during the follow-up were considered cured. Egg reduction rate (ERR) was calculated as the decrement in the infection intensity (group's geometric mean egg counts per 10 ml of urine) following treatment expressed as a proportion of the pre-treatment infection intensity. Before treatment, 80 out of the 400 children enrolled in the study tested positive for S. haematobium (20.0% (95% confidence interval (CI) 16.4-24.2%). Of these, 41 had infections of heavy intensity (51.3%) while the rest (48.7%) were of light intensity. Five weeks post-treatment, 10 children who had heavy intensity infection were diagnosed with S. haematobium (prevalence: 2.5% (95% CI 1.5-4.9%). Infection intensities decreased significantly from 45.9 (95% CI: 31.0-68.0) eggs/ 10 ml urine to1.4 (95% CI: 1.1-1.7) eggs/ 10 ml urine during pre-and post-treatment respectively. The ERR was 96.9%. There were no severe adverse events during follow up 24 hours post treatment. Treatment tolerability among the 400 children was high as none of the children spat and/ or vomited as observed in this study. CONCLUSION/SIGNIFICANCE: The study revealed that crushed PZQ is safe and effective in the treatment of urogenital schistosomiasis in this age group. It is therefore recommended that PZQ should be administered to the PSC in Kwale County.

Determination in vivo viability of a transfused platelet product by corrected count increment and percentage platelet response.

INTRODUCTION: For many years, platelet concentrates have been used for the prevention as well as treatment of bleeding disorders, especially in those patients with haematological problems involving platelet disorders as well as refractoriness, In addition, platelet concentrates (PCs) have been widely used to support patients undergoing bone marrow transplantation or who are receiving myelotoxic treatments. The aim of this study was to determine the quality of platelet concentrates by assessing platelet counts, volume, pH changes, swirling, residue of the red blood cells and white blood cell counts. Assess the in vivo viability of a transfused platelet product using the corrected count increment (CCI) and the percentage platelets response (PPR). This descriptive analysis study was done in Kenyatta National Hospital Blood Transfusion Unit between July 2016 and December 2016. METHODS: The in vitro Platelets concentrates quality was accurately determined and assessed using certain parameters. Platelet concentrates in ethylene diamine tetra acetic acid (EDTA) was used for analysis using Cell-Dyn 3700 analyser. The volume of PCs used was an average of 2mls of PCs, the pH was measured using digitalised Hanna edge pH kit. Agitation was done using Helmer agitator and centrifugation was done using Roto silenta 630 RS centrifuge. The in vivo viability of a transfused product was determined using corrected count increment (CCI) and percentage recovery (PR) between 1 and 20-hour after transfusion. Pre and post-transfused whole blood in EDTA collected from the recipients was analysed to access the functional platelets in the circulation. Data analysis was done using SPSS. RESULTS: A total of 384 platelet concentrates were analysed and used in transfusion. The majority 96, (40%) were O Rhesus D+ and the least being AB Rhesus D-at (1%).Centrifugation, separation and agitation was done according to standard procedure (n=384). Only (246 (65%) of the concentrates were found fit for use out of a total of (n=384) leaving 138 (35%) which did not meet the KNH/KNBTS criteria. The minimum specifications for platelet count are 5.5 x (109). The duration of 3 days of storage on average, the WBC count (109) was Mean ± SD 4.50 ± 3.50. Using the Hanna edge pH kit the pH Mean was ±SD 7.18 ± 8.82 and the used Volume (Mls) was at 55 ± 15. The concentrate was issued within 3 days of processing. After transfusion, the percentage platelet response (PPR) was 72% in male recipients at 1-hour and 30% at 20-hours while 69% in female recipients at 1-hour and 25% at 20-hours. The invivo viability of platelet product had a corrected count increment (CCI) of 75% ≥ 7500 at 1-hour and CCI of18% ≥ 30% at 20-hours in male recipients. In the same study, the female recipients had a CCI of 80% ≥ 7500 at 1-hour and a CCI of 25% ≥ 30% at 20-hours. CONCLUSION: The findings on platelets concentrates quality 65% met platelets transfusion criteria while 35% did not. On preparation of platelets concentrates there was high counts of white blood cells 4.5±3.5×109than recommended counts by Kenya National Blood Transfusion Services < 0.83×109. Both percentage platelet response (PPR) and corrected count increment (CCI) were very low at 20 hours compared to British committee for standards haematology criteria for successful increment of platelet products (PPR ≥ 30% and CCI ≥ 7500). Apheresis platelets transfusion can be introduced at KNH and use of leukoreduction performed on the platelet concentrates which are prepared within the Hospital. With such rate of refractoriness, additional tests to confirm the real cause of unviability of platelets in the patients need to be performed. Recipients should be done evaluation of the pattern of refractoriness followed by HLA compatibility testing. In addition, if there is a high, compatible cross-matched, selected apheresis platelet concentrate pint should be transfused. This unviability was due to recipients with either immune-mediated refractoriness or non-immune mediated refractoriness.

Prevalence of Soil-Transmitted Helminthiases and Schistosomiasis in Preschool Age Children in Mwea Division, Kirinyaga South District, Kirinyaga County, and Their Potential Effect on Physical Growth.

Intestinal parasitic infections can significantly contribute to the burden of disease, may cause nutritional and energetic stress, and negatively impact the quality of life in low income countries of the world. This cross-sectional study done in Mwea irrigation scheme, in Kirinyaga, central Kenya, assessed the public health significance of soil-transmitted helminthiases (STH), schistosomiasis, and other intestinal parasitic infections, among 361 preschool age children (PSAC) through fecal examination, by measuring anthropometric indices, and through their parents/guardians, by obtaining sociodemographic information. Both intestinal helminth and protozoan infections were detected, and, among the soil-transmitted helminth parasites, there were Ascaris lumbricoides (prevalence, 3%), Ancylostoma duodenale (<1%), and Trichuris trichiura (<1%). Other intestinal helminths were Hymenolepis nana (prevalence, 3.6%) and Enterobius vermicularis (<1%). Schistosoma mansoni occurred at a prevalence of 5.5%. Interestingly, the protozoan, Giardia lamblia (prevalence, 14.7%), was the most common among the PSAC. Other protozoans were Entamoeba coli (3.9%) and Entamoeba histolytica (<1). Anthropometric indices showed evidence of malnutrition. Intestinal parasites were associated with hand washing behavior, family size, water purification, and home location. These findings suggest that G. lamblia infection and malnutrition may be significant causes of ill health among the PSAC in Mwea, and, therefore, an intervention plan is needed.

Cryptosporidium infection in calves and the environment in Asembo, Western Kenya: 2015.

INTRODUCTION: Cryptosporidium species, a zoonotic enteric coccidian parasite, is among the leading causes of diarrhea in children. We evaluated the prevalence of Cryptosporidium infections in calves, factors associated with calf infection, environmental contamination of manure by Cryptosporidium and factors that expose humans to zoonotic transmission in Asembo. METHODS: in a cross-sectional study conducted from January to July 2015, we collected fecal specimens from 350 randomly selected calves aged ≤ 6 months old and 187 manure samples from the same farms. We assessed farmers' knowledge about Cryptosporidium and collected data on characteristics using structured questionnaires. Modified Ziehl Nielsen staining was used to detect Cryptosporidium oocysts from calves' stool and manure. The prevalence of infected calves and 95% confidence interval (CI) were calculated. Odds ratios (OR) and 95% (CI) were calculated to identify possible factors associated with Cryptosporidium infection; multivariable logistic regression performed to identify factors independently associated with the presence of Cryptosporidium. RESULTS: calves' fecal Cryptosporidium prevalence was 8.3% (95% CI: 5.7-11.8) and 7.5% (95% CI: 4.2-12.2) in manure. Odds of infection was higher in calves with loose stool compared to those with normal stool (AOR = 6.1, 95% C.I: 2.2-16.9), calves ≤ 2 months old compared to older calves (AOR=12.7, 95% C.I: 4.5-35.8) and calves in poor sanitation compared to calves in good hygienic conditions (AOR = 9.9, 95% C.I: 3.1-30.7). CONCLUSION: presence of Cryptosporidium species in calves and environment and reported human contact with animals increases zoonotic risk. We recommend further studies that determine specific Cryptosporidium species infecting animals and humans which would better estimate risk of disease transmission to humans.

Agricultural chemicals: life changer for mosquito vectors in agricultural landscapes?

BACKGROUND: Although many mosquito species develop within agricultural landscapes where they are potentially exposed to agricultural chemicals (fertilizers and pesticides), the effects of these chemicals on mosquito biology remain poorly understood. This study investigated the effects of sublethal concentrations of four agricultural chemicals on the life history traits of Anopheles arabiensis and Culex quinquefasciatus mosquitoes. METHODS: Field and laboratory experiments were conducted to examine how sublethal concentrations of four agricultural chemicals: an insecticide (cypermethrin), a herbicide (glyphosate), and two nitrogenous fertilizers (ammonium sulfate and diammonium phosphate) alter oviposition site selection, emergence rates, development time, adult body size, and longevity of An. arabiensis and Cx. quinquefasciatus. RESULTS: Both mosquito species had preference to oviposit in fertilizer treatments relative to pesticide treatments. Emergence rates for An. arabiensis were significantly higher in the control and ammonium sulfate treatments compared to cypermethrin treatment, while emergence rates for Cx. quinquefasciatus were significantly higher in the diammonium phosphate treatment compared to glyphosate and cypermethrin treatments. For both mosquito species, individuals from the ammonium sulfate and diammonium phosphate treatments took significantly longer time to develop compared to those from cypermethrin and glyphosate treatments. Although not always significant, males and females of both mosquito species tended to be smaller in the ammonium sulfate and diammonium phosphate treatments compared to cypermethrin and glyphosate treatments. There was no significant effect of the agrochemical treatments on the longevity of either mosquito species. CONCLUSIONS: These results demonstrate that the widespread use of agricultural chemicals to enhance crop production can have unexpected effects on the spatial distribution and abundance of mosquito vectors of malaria and lymphatic filariasis.

Red cell allo- and autoimmunisation in transfused sickle cell and cancer patients in Kenyatta National Hospital, Nairobi, Kenya.

BACKGROUND: Currently, no data are available on the prevalence of red blood cell (RBC) antibody formation amongst Kenyan patients with multiple transfusion needs, such as patients with sickle cell disease (SCD) or haematological malignancies (HM) and solid (SM) malignancies. OBJECTIVES: We determined the prevalence and specificities of RBC alloantibodies and autoantibodies in two patient groups with recurrent transfusion demands at Kenyatta National Hospital, Nairobi, Kenya. METHOD: Between February and August 2014, 300 samples from SCD, HM and SM patients were collected and screened for alloantibodies. Samples from 51 healthy blood donors were screened for irregular antibodies and phenotyped. RESULTS: Amongst the 228 patients with viable samples (SCD, n = 137; HM, n = 48; SM, n = 43), the median transfusion frequency was two to three events per group, 38 (16.7%) were RBC immunised and 32 (14.0%) had a positive direct antiglobulin test. We identified specific alloantibodies in six patients (2.6%). Four of these six were SCD patients (2.9%) who had specific RBC alloantibodies (anti-Cw, anti-M, anti-Cob, anti-S); amongst HM patients one had anti-K and one had anti-Lea. RBC autoantibody prevalence was 3.1% (7/228). Amongst the healthy blood donors, the Ror, ccD.ee and R2r, ccD.Ee phenotypes accounted for 82% of the Rhesus phenotypes and all were Kell negative. CONCLUSION: The numbers of transfusions and the rates of RBC alloantibodies are low and the most important RBC alloantibody-inducing blood group antigens are relatively homogeneously distributed in this population. A general change in the Kenyatta National Hospital pre-transfusion test regimen is thus not necessary. The current transfusion practice should be reconsidered if transfusion frequencies increase in the future.

Plasmodium berghei calcium dependent protein kinase 1 is not required for host cell invasion.

Plasmodium Calcium Dependent Protein Kinase (CDPK1) is required for the development of sexual stages in the mosquito. In addition, it is proposed to play an essential role in the parasite's invasive stages possibly through the regulation of the actinomyosin motor and micronemal secretion. We demonstrate that Plasmodium berghei CDPK1 is dispensable in the parasite's erythrocytic and pre-erythrocytic stages. We successfully disrupted P. berghei CDPK1 (PbCDPK1) by homologous recombination. The recovery of erythrocytic stage parasites lacking PbCDPK1 (PbCDPK1-) demonstrated that PbCDPK1 is not essential for erythrocytic invasion or intra-erythrocytic development. To study PbCDPK1's role in sporozoites and liver stage parasites, we generated a conditional mutant (CDPK1 cKO). Phenotypic characterization of CDPK1 cKO sporozoites demonstrated that CDPK1 is redundant or dispensable for the invasion of mammalian hepatocytes, the egress of parasites from infected hepatocytes and through the subsequent erythrocytic cycle. We conclude that P. berghei CDPK1 plays an essential role only in the mosquito sexual stages.