Effects of Allium Sativum Ethanolic Extract on Trypanosoma brucei brucei Parasites' Morphometric Parameters and Clinical Outcome in White Albino Laboratory Rats

BACKGROUND Trypanosomosis affects humans as well as wild and domestic vertebrates, yet has no successful prophylaxis, chemotherapy nor cure. OBJECTIVES The study was to investigate the effects of Allium sativum extract on Trypanosoma brucei brucei parasites' morphometric parameters, parasitemia and the clinical outcome in white infected Albino laboratory rats in order to determine its trypanocidal effects. METHODOLOGY The study was conducted at the department of Biological Sciences Laboratory of the Moi University Eldoret. Thirty two (32) mature rats randomly divided into four groups (M, N, P and Q) were kept in four (4) cages in a well ventilated room, with adequate light supply in the day. Sixteen (16) rats were infected with T. b. brucei (1.0 x 104 parasites per rat); eight (8) of which (Group N) were treated with the A. sativum ethanolic extract on day 5 and day 9 after infection, while the other eight (8)rats (Group Q) received saline treatment on the same days. Sixteen (16) non-infected rats (controls) were also divided into two groups of eight rats each (P and M) and treated as in group N and Q, respectively. The rats were obtained from University of Nairobi, Chiromo Campus. RESULTS All infected rats became parasitemic two days after infection and reached peak levels on day 4 and 5 post infection. Parasitemia in saline treated infected rats fluctuated between 4025.5 ± 0.05 - 5544.4 ± 0.05 parasites per 200WBC whereas in the extract treated rats parasitemia declined from 6976.6 ± 0.05 - 311.0 ± 0.05 parasites per 200WBC after the first treatment. Uninfected saline treated rats maintained normal Hb level (10.6g/L to 11.8g/L) as compared to the uninfected extract treated rats' whose Hb levels was at 13.41g/L to 14.36g/L. The haemoglobin level changed to 8.0g/L four days after the infection in the group N rats before rising to 10.2g/L on day 8 post-infection following the extract treatments. Group Q rats' Hb declined to 6.43g/L by the end of the study. RBC count of the infected saline treated rats declined to 3.38 x 106/µL as compared to 4.93-7.61 x 106/µL in the normal rats by 11 days postinfection.There was however no significant change in WBC, temperature and weight between the saline extract treated rats. The extract produced a shrinking effect on the parasite's body with some of the morphometric parameters appearing significantly (P<0.05) reduced as observed under a microscope with ocular and stage micrometer scale. The mean nucleus, posterior ends to nucleus centre, the nucleus centre to the anterior end and the body length were reduced from 2.41µm to 1.42µm(P=0.00), 4.42µm to 3.68µm(P=0.017) , 4.65µm to 4.18µm(P=0.001) and 8.58µm to 7.19µm(P=0.001) respectively. CONCLUSION In conclusion it was evident that, A. sativum ethanolic extract exhibited Trypanocidal effects that can be exploited to control clinical progression of Trypanosomosis in rats. In addition, the data presented demonstrates the plant extract had the potential to improve the red and white blood cell indices reducing parasitaemia following T. b. brucei infection. These findings suggest that, the garlic extract affected the plasma membrane of the parasites since shrinking was only possible with disrupted membrane biochemistry

Changes in antigen-specific cytokine and chemokine responses to Plasmodium falciparum antigens in a highland area of Kenya after a prolonged absence of malaria exposure.

Individuals naturally exposed to Plasmodium falciparum lose clinical immunity after a prolonged lack of exposure. P. falciparum antigen-specific cytokine responses have been associated with protection from clinical malaria, but the longevity of P. falciparum antigen-specific cytokine responses in the absence of exposure is not well characterized. A highland area of Kenya with low and unstable malaria transmission provided an opportunity to study this question. The levels of antigen-specific cytokines and chemokines associated in previous studies with protection from clinical malaria (gamma interferon [IFN-γ], interleukin-10 [IL-10], and tumor necrosis factor alpha [TNF-α]), with increased risk of clinical malaria (IL-6), or with pathogenesis of severe disease in malaria (IL-5 and RANTES) were assessed by cytometric bead assay in April 2008, October 2008, and April 2009 in 100 children and adults. During the 1-year study period, none had an episode of clinical P. falciparum malaria. Two patterns of cytokine responses emerged, with some variation by antigen: a decrease at 6 months (IFN-γ and IL-5) or at both 6 and 12 months (IL-10 and TNF-α) or no change over time (IL-6 and RANTES). These findings document that P. falciparum antigen-specific cytokine responses associated in prior studies with protection from malaria (IFN-γ, TNF-α, and IL-10) decrease significantly in the absence of P. falciparum exposure, whereas those associated with increased risk of malaria (IL-6) do not. The study findings provide a strong rationale for future studies of antigen-specific IFN-γ, TNF-α, and IL-10 responses as biomarkers of increased population-level susceptibility to malaria after prolonged lack of P. falciparum exposure.

Symptomatic malaria diagnosis overestimate malaria prevalence, but underestimate anaemia burdens in children: results of a follow up study in Kenya.

BACKGROUND: The commonly accepted gold standard diagnostic method for detecting malaria is a microscopic reading of Giemsa-stained blood films. However, symptomatic diagnosis remains the basis of therapeutic care for the majority of febrile patients in malaria endemic areas. This study aims to compare the discrepancy in malaria and anaemia burdens between symptomatic diagnosed patients with those diagnosed through the laboratory. METHODS: Data were collected from Western Kenya during a follow-up study of 887 children with suspected cases of malaria visiting the health facilities. In the laboratory, blood samples were analysed for malaria parasite and haemoglobin levels. Differences in malaria prevalence between symptomatic diagnosis and laboratory diagnosis were analysed by Chi-square test. Bayesian probabilities were used for the approximation of the malaria and anaemia burdens. Regression analysis was applied to: (1) determine the relationships between haemoglobin levels, and malaria parasite density and (2) relate the prevalence of anaemia and the prevalence of malaria. RESULTS: The prevalence of malaria and anaemia ranged from 10% to 34%, being highest during the rainy seasons. The predominant malaria parasite was P. falciparum (92.3%), which occurred in higher density in children aged 2‒5 years. Fever, high temperature, sweating, shivering, vomiting and severe headache symptoms were associated with malaria during presumptive diagnosis. After conducting laboratory diagnosis, lower malaria prevalence was reported among the presumptively diagnosed patients. Surprisingly, there were no attempts to detect anaemia in the same cohort. There was a significant negative correlation between Hb levels and parasite density. We also found a positive correlation between the prevalence of anaemia and the prevalence of malaria after laboratory diagnosis indicating possible co-occurrence of malaria and anaemia. CONCLUSION: Symptomatic diagnosis of malaria overestimates malaria prevalence, but underestimates the anaemia burden in children. Good clinical practice dictates that a laboratory should confirm the presence of parasites for all suspected cases of malaria.

Estimation of recent and long-term malaria transmission in a population by antibody testing to multiple Plasmodium falciparum antigens.

BACKGROUND: Tools that estimate recent and long-term malaria transmission in a population would be highly useful for malaria elimination programs. METHODS: The prevalence of antibodies to 11 Plasmodium falciparum antigens was assessed by cytometric bead assay or enzyme-linked immunosorbent assay in 1000 people in a highland area of Kenya over 14 months, during a period of interrupted malaria transmission. RESULTS: Antibodies differed by antigen in acquisition with age: rapid (>80% antibody positive by age 20 years, 5 antigens), moderate (>40% positive by age 20 years, 3 antigens), or slow (<40% positive by age 20 years, 3 antigens). Antibody seroreversion rates in the 14 months between samples decreased with age rapidly (7 antigens), slowly (3 antigens), or remained high at all ages (schizont extract). Estimated antibody half-lives in individuals >10 years of age were long (40 to >80 years) for 5 antigens, moderate (5-20 years) for 3 antigens, and short (<1 year) for 3 antigens. CONCLUSIONS: Antibodies to P. falciparum antigens in malaria-endemic areas vary by age, antigen, and time since last exposure to P. falciparum. Multiplex P. falciparum antibody testing could provide estimates of long-term and recent malaria transmission and potentially of a population's susceptibility to future clinical malaria.

Development of clinical immunity to malaria in highland areas of low and unstable transmission.

In highland areas of unstable, low malaria transmission, the extent to which immunity to uncomplicated malaria develops with age and intermittent parasite exposure has not been well characterized. We conducted active surveillance for clinical malaria during April 2003-March 2005 in two highland areas of western Kenya (Kapsisiywa and Kipsamoite). In both sites, annual malaria incidence was significantly lower in persons ≥ 15 years of age than in persons < 5 years of age (Kapsisiywa: incidence = 382.9 cases/1,000 persons among persons < 1-4 years of age versus 135.1 cases/1,000 persons among persons ≥ 15 years of age; Kipsamoite: incidence = 233.0 cases/1,000 persons in persons < 1-4 years of age versus 43.3 cases/1,000 persons in persons ≥ 15 years of age). In Kapsisiywa, among persons with malaria, parasite density and axillary body temperature were also significantly lower in persons ≥ 15 years of age than in persons < 5 years of age. Even in highland areas of unstable and low malaria transmission, age is associated with development of clinical immunity to malaria.

Possible interruption of malaria transmission, highland Kenya, 2007-2008.

Highland areas where malaria transmission is unstable are targets for malaria elimination because transmission decreases to low levels during the dry season. In highland areas of Kipsamoite and Kapsisiywa, Kenya (population approximately 7,400 persons), annual household indoor residual spraying with a synthetic pyrethroid was performed starting in 2005, and artemether/lumefantrine was implemented as first-line malaria treatment in October 2006. During April 2007-March 2008, no microscopy-confirmed cases of malaria occurred at the sites. In 4 assessments of asymptomatic persons during May 2007-April 2008, a total of <0.3% of persons were positive for asexual Plasmodium falciparum by microscopy or PCR at any time, and none were positive by PCR at the last 2 sample collections. Our findings show that in such areas, interruption and eventual elimination of malaria transmission may be achievable with widespread annual indoor residual spraying of households and artemisinin combination therapy.