Willy K. Tonui

Anti-parasitic activity and cytotoxicity of selected medicinal plants from Kenya.

Indigenous rural communities in the tropics manage parasitic diseases, like malaria and leishmaniasis, using herbal drugs. The efficacy, dosage, safety and active principles of most of the herbal preparations are not known. Extracts from 6 selected plant species, used as medicinal plants by indigenous local communities in Kenya, were screened for in vitro anti-plasmodial and anti-leishmanial activity, against 2 laboratory-adapted Plasmodium falciparum isolates (D6, CQ-sensitive and W2, CQ-resistant) and Leishmania major (IDU/KE/83=NLB-144 strain), respectively. The methanol extract of Suregada zanzibariensis leaves exhibited good anti-plasmodial activity (IC(50) 4.66+/-0.22 and 1.82+/-0.07 microg/ml for D6 and W2, respectively). Similarly, the methanol extracts of Albizia coriaria (IC(50) 37.83+/-2.11 microg/ml for D6) and Aspergillus racemosus (32.63+/-2.68 and 33.95+/-2.05 microg/ml for D6 and W2, respectively) had moderate anti-plasmodial activity. Acacia tortilis (IC(50) 85.73+/-3.36 microg/ml for W2) and Albizia coriaria (IC(50) 71.17+/-3.58 microg/ml for W2) methanol extracts and Aloe nyeriensis var kedongensis (IC(50) 87.70+/-2.98 and 67.84+/-2.12 microg/ml for D6 and W2, respectively) water extract exhibited mild anti-plasmodial activity. The rest of the extracts did not exhibit any anti-plasmodial activity. Although the leishmanicidal activity of extracts were lower than for pentosam (80%), reasonable activity was observed for Aloe nyeriensis methanol (68.4+/-6.3%), Albizia coriara water (66.7+/-5.0%), Maytenus putterlickoides methanol (60.0+/-6.23%), Asparagus racemosus methanol and water (58.3+/-8.22 and 56.8+/-6.58%, respectively), Aloe nyeriensis water (53.3+/-5.1%) and Acacia tortilis water (52.9+/-6.55%) extracts at 1000 microg/ml. Leishmania major infected macrophages treated with methanol extracts of Suregada zanzibariensis and Aloe nyeriensis var kedongensis and pentostam had infection rates of 28+/-2.11, 30+/-1.22 and 40+/-3.69%, respectively at 1000 microg/ml, indicating better anti-leishmanial activity for the extracts. The methanol extract of Albizia coriara (44.0+/-3.69%) and aqueous extracts of Asparagus racemosus (42+/-3.84%) and Acacia tortilis (44+/-5.59%) had similar activity to pentosam. Multiplication indices for Leishmania major amastigotes treated with methanol extracts of Albizia coriaria, Suregada zanzibariensis and Aloe nyeriensis var kedongensis, aqueous extract of Acacia tortilis and pentosam were 28.5+/-1.43, 29.4+/-2.15, 31.1+/-2.22, 35.9+/-3.49 and 44.0+/-3.27%, respectively, at 1000 microg/ml, confirming better anti-leishmanial activity for the extracts. Aqueous extracts of Aloe nyeriensis (46.7+/-3.28%) and Albizia coriaria (47.5+/-3.21%) had similar activity level to pentosam. The plant extracts have better inhibitory activity while pentosam has better leishmanicidal activity. All extracts exhibited very low cytotoxicity (CC(50) > 500 microg/ml) against human embryonic lung fibroblast (HELF) cells. The investigations demonstrated the efficacy and safety of some extracts of plants that are used by rural indigenous communities for the treatment of parasitic diseases.

A review of Leishmaniasis in Eastern Africa

Abstract The review presents the epidemiology of leishmaniasis in the Eastern Africa region. We searched PUB MED and MEDLINE with several key words-namely, “leishmaniasis”;“cutaneous”, “diffuse cutaneous”, “mucosal”, and “visceral leishmaniasis”; “kala azar”, and “post kala azar dermal leishmaniasis”, -for recent clinical and basic science articles related to leishmaniasis in countries in the Eastern Africa region. Poverty, wars, conflicts and migration have significantly aggravated leishmaniases in Eastern Africa. Of particular concern is the increasing incidence of Leishmania-HIV co-infection in Ethiopia where 20∼40% of the persons affected by visceral leishmaniasis are HIV-co-infected. Sudan has the highest prevalence rate of post kala-azar dermal leishmaniasis(PKDL) in the world, a skin complication of visceral leishmaniasis(VL) that mainly afflicts children below age ten. In view of its spread to previously non-endemic areas and an increase in imported cases, leishmaniasis in Eastern Africa should be considered a health emergency.

International Biosafety and Biosecurity Challenges: Suggestions for Developing Sustainable Capacity in Low-resource Countries

The increased global demand for improved disease detection and control has resulted in the expansion of diagnostic and research capacity. However, the increase in infectious disease detection capacity has not necessarily been paralleled by an increase in biosafety and biosecurity capacity, particularly in low-resource countries. Low-resource countries face numerous challenges that severely constrain the development, or expansion, of sustainable capacity in biosafety and biosecurity management. This article divides these challenges into nine broad categories: 1) Country-/Region-specific Regulatory Framework and Guidelines or Standards; 2) Biosafety Awareness; 3) Infrastructure; 4) Equipment, Reagents, and Services; 5) Management Processes and Administrative Controls; 6) Biosafety Curricula; 7) Training; 8) Biosafety Associations, Professional Competency, and Credentialing; and 9) Individual Mentoring and Organizational Twinning. Overcoming these challenges requires the collaborative efforts of representatives from the highest levels of local governments, the international biosafety community (e.g., international, regional, and national biosafety associations), and international development partners (e.g., national government agencies and programs, World Health Organization (WHO), World Bank, Food and Agriculture Organization of the United Nations (FAO), and the World Organization for Animal Health (OIE) to identify, fund, and execute solutions for sustainable capacity development. Collaboration is required to develop solutions appropriate for the specific needs and available resources within any given country.

Immunostimulatory responses to crude extracts of Warburgia ugandensis (Sprague) subsp ugandensis (Canellaceae) by BALB/c mice infected with Leishmania major.

Introduction To determine the immunostimulatory potential of crude extracts of Warburgia ugandensis subsp. ugandensis with a soluble leishmanial antigen in vaccinating BALB/c mice. Methods Seventy two female BALB/c mice were randomly assigned into six groups. The mice were vaccinated with soluble leishmania antigens (SLA) alone, hexane, ethyl acetate, and dichloromethane extract co-administered with SLA. Unvaccinated mice formed the control group. The induction of cell-mediated immunity following vaccination was determined by measuring in vitro lymphocyte proliferation and the production of interleukin (IL)-4 and gamma interferon (IFN-γ) determined by flow cytometry. Protection against L. major was determined by quantifying parasite burdens in L. major infected footpads using a limiting dilution assay and by measuring lesion sizes of the infected footpad compared to the contralateral uninfected footpad. Results On vaccination with extracts of W. ugandensis subsp. ugandensis alone or as adjuvants when used in combination with Leishmania antigens, the hexane extract and the dichloromethane extract plus SLA stimulated moderate production of IFN-γ and low levels of IL-4.These mice were partially protected from cutaneous leishmaniasis as shown by the slow development of lesions and comparatively less parasite burdens. Conclusion These data suggest that extracts of W. ugandensis subsp. ugandensis are suitable adjuvants for Leishmania vaccines. However, since W. ugandensis subsp. ugandensis has been shown to be effective against Leishmania parasites in vitro and in vivo, further studies ought to be conducted to determine its immunochemotherapeutic potential when co-administered with a soluble leishmanial antigen in vaccinating BALB/c mice.

Evaluation of the adjuvanticity of artemisinin with soluble Leishmania major antigens in BALB/c mice

Objective To determine the adjuvant potential of artemisinin with a soluble leishmanial antigen in vaccinating BALB/c mice.

Evaluation of the immunochromatographic strip test for the rapid diagnosis of antenatal syphilis in women in Eldoret, Kenya

Abstract Objective This study compared the performance of the immunochromatographic strip (ICS) to the Venereal Disease Research Laboratory (VDRL) test and Treponema pallidum haemagglutination assay (TPHA) at a primary health care setting. Methods The study group was comprised of 150 females randomly drawn from a population of pregnant women attending their first antenatal visit or follow-up visits at West Maternity Hospital in Eldoret Kenya, but without a previous syphilis test during that pregnancy. On-site VDRL, ICS and TPHA tests were performed and immediate treatment provided where appropriate. The performance of the three tests was compared. Results The sero-prevalence of syphilis as determined by the VDRL test was 3%. There was no significant difference between the ICS and the VDRL test (P > 0.05). The sensitivity and specificity of the ICS test were 80% and 98.6% respectively, while the negative predictive value (NPV) and positive predictive value (PPV) were both 100%. On the other hand, the sensitivity and specificity of the VDRL test were 66.7% and 99.3%, while the NPV and PPV were 80% and 98.6% respectively. The Treponema pallidum haemagglutination assay was used as a reference test and had sensitivity, specificity, NPV and PPV of 100%. Conclusion The diagnostic accuracy of the ICS compared favorably with the VDRL gold standard. The use of the ICS in Kenya can improve the diagnosis of syphilis in health facilities both with and without laboratories and allow community health care workers to make a rapid diagnosis of the disease, and consequently make immediate therapeutic decisions.