Expanding beyond zoonoses: the benefits of a national One Health coordination mechanism to address antimicrobial resistance and other shared health threats at the human-animal-environment interface in Kenya.

In order to manage global and transnational health threats at the human- animal-environment interface, a multisectoral One Health approach is required. Threats of this nature that require a One Health approach include, but are not limited to, emerging, endemic and re-emerging zoonotic diseases, food safety, antimicrobial resistance (AMR), vector-borne and neglected infectious diseases, toxicosis and pesticides. Relevant Kenyan authorities formally institutionalised One Health in 2011 through the establishment of the Zoonotic Disease Unit (ZDU) and its advisory group, the Zoonoses Technical Group. At that time, the One Health agenda focused on zoonotic diseases. As the issue of AMR began to gain traction globally, a One Health approach to its management was advocated in Kenya in 2015. This paper summarises a series of interviews (with respondents and key informants) that describe how AMR institutionalisation evolved in Kenya. It also examines how responses to other health threats at the human-animal- environment interface were coordinated and used to identify gaps and make recommendations to improve One Health coordination at the national level in Kenya. Results showed that the road to the institutionalisation of AMR through the National Action Plan on Prevention and Containment of Antimicrobial Resistance, 2017-2022 and a formally launched One Health coordination mechanism, the National Antimicrobial Stewardship Interagency Committee (NASIC), took ten years. Moreover, supplementary actions are still needed to further strengthen AMR coordination. In addition to the ZDU and NASIC, Kenya has established two other formal multisectoral and multidisciplinary coordination structures, one for aflatoxicosis and the other for health threats associated with pesticide use. The country has four distinct and separate One Health coordination mechanisms: for zoonoses, for AMR, for aflatoxicosis and for the health threats associated with pesticide use. The main gap lies in the lack of overall coordination between these topic-specific structures. An overall coordination mechanism for all One Health issues is therefore needed to improve synergy and complementarity. None of the topic-specific mechanisms plays a critical role in the policy development process, institutionalisation or implementation of activities related to the other topic areas. The authors recommend renaming the ZDU as the One Health Office, and expanding it to include AMR and food safety teams, and their associated technical working groups. Through this restructuring, the One Health Office would become an umbrella organisation dealing with all four issues mentioned above. Based on Kenya's experience, the authors recommend that other countries also consider expanding the scope of multisectoral One Health coordination mechanisms to include other shared health threats.

La gestion des menaces sanitaires mondiales et transnationales à l'interface homme­animal­environnement nécessite de faire appel à une approche Une seule santé multisectorielle. Les menaces de cette nature appelant une approche Une seule santé sont notamment (mais ne s'y limitent pas) les maladies zoonotiques émergentes, endémiques et réémergentes, la sécurité sanitaire des aliments, la résistance aux agents antimicrobiens, les maladies à transmission vectorielle, les maladies infectieuses négligées, les toxicoses et les pesticides. Les autorités kényanes ont institutionnalisé formellement l'approche Une seule santé en 2011 en mettant en place l'Unité Maladies zoonotiques (ZDU : Zoonotic Disease Unit) et son groupe consultatif, le Groupe technique Zoonoses. Le programme d'activités Une seule santé était alors centré sur les maladies zoonotiques. La problématique de l'antibiorésistance ayant gagné du terrain à l'échelle mondiale, en 2015 il a été préconisé de recourir à l'approche Une seule santé pour y faire face au Kenya. Les auteurs résument une série d'entretiens conduits auprès d'interlocuteurs et d'acteurs clés concernant l'évolution de l'institutionnalisation de la lutte contre la résistance aux agents antimicrobiens au Kenya. Ils mettent également en lumière le déroulement de la coordination des réponses mises en place pour contrer d'autres menaces sanitaires à l'interface homme­animal­environnement et l'éclairage que ces réponses ont permis d'apporter afin d'identifier les lacunes et de formuler des recommandations pour améliorer la coordination Une seule santé à l'échelle nationale. Il ressort de cette analyse qu'il a fallu dix ans pour que le Kenya institutionnalise le domaine de l'antibiorésistance à travers le Plan d'action national pour la prévention et la maîtrise de l'antibiorésistance (2017­2022) et pour qu'il mette en place un mécanisme officiel de coordination Une seule santé, le Comité national inter-agences de gestion concertée des agents antimicrobiens (NASIC : National Antimicrobial Stewardship Interagency Committee). Il est également apparu que des mesures complémentaires devaient être prises pour renforcer la coordination en matière d'antibiorésistance. Outre le ZDU et le NASIC, deux autres structures officielles de coordination multidisciplinaires et multisectorielles ont été créées au Kenya, chargées respectivement de l'aflatoxicose et des menaces sanitaires en lien avec l'utilisation de pesticides. Le pays dispose donc de quatre mécanismes de coordination distincts portant respectivement sur les zoonoses, l'antibiorésistance, l'aflatoxicose et les menaces sanitaires liées à l'utilisation de pesticides. La faille centrale est l'absence de coordination d'ensemble entre ces structures thématiques. Il faut donc instituer un mécanisme de coordination général pour toutes les questions relevant de l'approche Une seule santé, afin d'améliorer les synergies et la complémentarité. Aucun des mécanismes thématiques ne joue de rôle déterminant dans le processus d'élaboration des politiques, l'institutionnalisation ou la mise en œuvre de mesures relevant des autres thématiques. Les auteurs recommandent de modifier le nom du ZDU en Bureau Une seule santé et d'en élargir les compétences pour intégrer les équipes chargées de l'antibiorésistance et de la sécurité sanitaire des aliments ainsi que leurs groupes de travail techniques respectifs. Suite à cette restructuration, le Bureau Une seule santé pourrait devenir l'organisation transversale traitant des quatre thèmes précités. En se basant sur l'expérience du Kenya, les auteurs recommandent que d'autres pays s'engagent à leur tour sur la voie d'un élargissement de la portée des mécanismes de coordination multisectoriels Une seule santé afin d'inclure d'autres menaces sanitaires communes.

Para lidiar con las amenazas sanitarias mundiales o transnacionales en la interfaz de personas, animales y medio ambiente es preciso trabajar desde la óptica multisectorial de Una sola salud. Este tipo de amenazas que apelan al concepto de Una sola salud son, entre otras, las enfermedades zoonóticas emergentes, endémicas o reemergentes, los factores que afectan a la inocuidad de los alimentos, las resistencias a los antimicrobianos, las enfermedades infecciosas de transmisión vectorial o desatendidas, las toxicosis y los efectos del uso de plaguicidas. En 2011, con la creación de la ZDU (Zoonotic Disease Unit: unidad de enfermedades zoonóticas) y de un grupo técnico sobre zoonosis encargado de asesorarla, las autoridades competentes kenianas pusieron en práctica oficialmente la noción de Una sola salud. En aquel momento los programas de Una sola salud se centraban sobre todo en las enfermedades zoonóticas. A partir de 2015, cuando las resistencias a los antimicrobianos empezaron a ganar terreno en todo el mundo, en Kenia se apostó por combatirlas desde la óptica de Una sola salud. Los autores, sintetizando la información obtenida con una serie de encuestas y entrevistas con informadores clave, describen la progresiva institucionalización en Kenia de la lucha contra esas resistencias. También explican cómo se coordinaron las actividades de respuesta a otras amenazas sanitarias surgidas en la interfaz de personas, animales y medio ambiente y cómo ello sirvió para detectar deficiencias y formular recomendaciones encaminadas a mejorar la coordinación en clave de Una sola salud en todo el territorio nacional. Los resultados demuestran que hicieron falta diez años para institucionalizar la lucha contra la resistencia a los antimicrobianos, materializada en un plan nacional de acción sobre prevención y contención de antibiorresistencias para 2017­2022 y en la creación oficial de un mecanismo de coordinación de Una sola salud, el NASIC (National Antimicrobial Stewardship Interagency Committee: comité nacional interinstitucional de gestión de antimicrobianos). No obstante, aún hacen falta más medidas para mejorar la coordinación en todo lo relativo a las antibiorresistencias. Además de la ZDU y el NASIC, Kenia ha creado otras dos estructuras oficiales de coordinación multisectorial y multidisciplinar, una para la aflatoxicosis y otra para las amenazas sanitarias derivadas del uso de plaguicidas. El país cuenta así con cuatro mecanismos distintos e independientes de coordinación en clave de Una sola salud, centrados en las zoonosis, las antibiorresistencias, la aflatoxicosis y los riesgos sanitarios ligados a los plaguicidas. La principal deficiencia estriba en la falta de coordinación global entre estas estructuras de carácter temático. Para lograr mayores cotas de sinergia y complementariedad, por lo tanto, se requiere un mecanismo de coordinación general de todos los ámbitos de trabajo que tocan a la noción de Una sola salud. Ninguno de los mecanismos temáticos cumple una función decisiva en el proceso de formulación de políticas o de institucionalización y ejecución de actividades relacionadas con los demás ámbitos temáticos. Los autores recomiendan que la ZDU pase a denominarse Oficina de Una sola salud y que sea ampliada para integrar en ella a los equipos encargados de las antibiorresistencias y la inocuidad de los alimentos y a los correspondientes grupos de trabajo técnicos. Con semejante reestructuración, la Oficina de Una sola salud pasaría a ser una supraentidad que abarcaría los cuatro temas ya mencionados. Teniendo en cuenta la experiencia de Kenia, los autores recomiendan que otros países se planteen también la posibilidad de ampliar la cobertura de los mecanismos de coordinación multisectorial de Una sola salud para que incluyan otras amenazas sanitarias que tengan elementos en común.

Removal of lead (II) from aqeouos waste using (CD-PCL-TiO2) bio-nanocomposites.

Lead (Pb) pollution is our water system is a major concern, as this metal is toxic even at low concentration. This study aim to fabricate a bio-nanocomposite (cyclodextrin-polycaprolactone titanium dioxide) that will be used as an adsorbent for the removal of lead in aqueous waste. In this study, titanium dioxide was synthesized via sol-gel technique then incorporated in a polymer blend (CD-PCL) via solution blending method. The resulting bio-nanocomposites were characterized using Scanning Electron Microscopy (SEM), transmission electron microscope (TEM) and Brunauer Emmett and Teller (BET). The effect of how factors such as pH, concentration and adsorbent dose affect the removal efficiency of the bio-nanocomposites were studies. Maximum adsorption of lead obtained was 98% at pH 9.7, 10 ppm with 0.005 g dosage. Kinetic studies and adsorption isotherms were also investigated. The adsorption data fit Langmuir isotherm. Pb (II) obeyed pseudo-second order kinetics.

First Complete Genome Sequences of Porcine Bocavirus Strains from East Africa.

Here, we report the first complete genome sequences of two strains of porcine bocavirus (JOA_011 and JOA_015) detected in Uganda and Kenya, respectively. These data will help in understanding the molecular and evolutionary characteristics of the porcine bocaviruses in this region and the development of appropriate diagnostic and control tools.

Food Security in HIV/AIDS Response: Insights from Homa Bay; Kenya

This paper examines the viability and effectiveness of a pilot farming initiative in reversing impacts of HIV/AIDS on the most affected households in Homa Bay; Kenya. The paper argues that once patients are stable; they can effectively be engaged in farming with minimal financial and technical support; resulting in enhanced food security of the affected households. More importantly; it helps to reduce HIV/AIDS-related stigma and improve the individual's self-esteem. Some of the key challenges of the pilot initiative were the limited number of agricultural extension workers and absence of facilities to enable them to deliver services to the farmers; the high cost of farm inputs; the unavailability of farm inputs when they were needed; poorly developed agricultural markets; and the absence of irrigation facilities. The paper recommends the sensitive scaling-up of this approach. However; farming initiatives by HIV/AIDS service NGOs should be linked to at least three key aspects: (a) treatment; care and support to HIV/AIDS affected households; (b) micro grant schemes or subsidies to enable farmers to purchase farming tools and farm inputs; and (c) comprehensive on-farm training support. To ensure effectiveness and wider reach; government needs to view agriculture through an HIV lens and promote a multisectoral approach that recognises the relationship between HIV/AIDS and food security. A number of immediate actions are required to strengthen this relationship; such as increased public investment to augment extension services; subsidise farm inputs; and develop infrastructure including agricultural markets

Challenges Associated with Scaling up Artemisinin Combination Therapy in Sub-Saharan Africa A Review Article.

Malaria is the leading cause of morbidity and mortality in Sub-Saharan Africa. One key strategic intervention is provision of early diagnosis and prompt effective treatment. A major setback has been the development of drug resistance to commonly used antimalarials. To overcome this, most countries in Sub-Saharan Africa have adopted Artemisinin Combination Therapy (ACT) as a first line treatment for uncomplicated malaria. Artemether Lumefantrine (AL) and Artesunate Amodiaquine (ASAQ) are the main drugs of choice. There are key implementation issues, which may have a bearing on the scaling up of this new treatment. This article reviewed the published papers on ACT with focus on sustainability, compliance, and diagnosis. ACTs are costly, but highly effective. Their scaling up is the most cost effective malaria intervention currently available. Most countries rely heavily on the Global Fund for their scaling up. AL has a short shelf life, a complicated six-dose regimen that requires intake with fat to ensure sufficient bioavailability. High rates of adherence have been reported. Use of parasitic diagnosis is advocated to ensure rational use. Parasitic diagnostics like rapid test and microscopy are currently inadequate. The majority of malaria cases may continue to be diagnosed clinically leading to over prescription of drugs. ACTs are currently not available at the community level for home based management of malaria. Issues related to safety and rational use need to be addressed before their use in the informal health sector like community drug sellers and community health workers. The majority of malaria cases at the community level could go untreated or continue to be treated using less effective drugs. We conclude that ACTs are highly effective. A major challenge is ensuring rational use and access at the household level. It is hoped that addressing these issues will increase the likelihood that ACT achieves its intended goals of reducing morbidity and mortality due to malaria, and delaying the onset of drug resistance.

Challenges Associated with Scaling Up Artemisinin Combination Therapy in Sub-Saharan Africa : A Review Article

Malaria is the leading cause of morbidity and mortality in Sub-Saharan Africa. One key strategic intervention is provision of early diagnosis and prompt effective treatment. A major setback has been the development of drug resistance to commonly used antimalarials. To overcome this; most countries in Sub-Saharan Africa have adopted Artemisinin Combination Therapy (ACT) as a first line treatment for uncomplicated malaria. Artemether Lumefantrine (AL) and Artesunate Amodiaquine (ASAQ) are the main drugs of choice. There are key implementation issues; which may have a bearing on the scaling up of this new treatment. This article reviewed the published papers on ACT with focus on sustainability; compliance; and diagnosis. ACTs are costly; but highly effective. Their scaling up is the most cost effective malaria intervention currently available. Most countries rely heavily on the Global Fund for their scaling up. AL has a short shelf life; a complicated six-dose regimen that requires intake with fat to ensure sufficient bioavailability. High rates of adherence have been reported. Use of parasitic diagnosis is advocated to ensure rational use. Parasitic diagnostics like rapid test and microscopy are currently inadequate. The majority of malaria cases may continue to be diagnosed clinically leading to over prescription of drugs. ACTs are currently not available at the community level for home based management of malaria. Issues related to safety and rational use need to be addressed before their use in the informal health sector like community drug sellers and community health workers. The majority of malaria cases at the community level could go untreated or continue to be treated using less effective drugs. We conclude that ACTs are highly effective. A major challenge is ensuring rational use and access at the household level. It is hoped that addressing these issues will increase the likelihood that ACT achieves its intended goals of reducing morbidity and mortality due to malaria; and delaying the onset of drug resistance

Challenges Associated with Scaling up Artemisinin Combination Therapy in Sub-Saharan Africa ; A Review Article

Malaria is the leading cause of morbidity and mortality in Sub-Saharan Africa. One key strategic intervention is provision of early diagnosis and prompt effective treatment. A major setback has been the development of drug resistance to commonly used antimalarials. To overcome this; most countries in Sub-Saharan Africa have adopted Artemisinin Combination Therapy (ACT) as a first line treatment for uncomplicated malaria. Artemether Lumefantrine (AL) and Artesunate Amodiaquine (ASAQ) are the main drugs of choice. There are key implementation issues; which may have a bearing on the scaling up of this new treatment. This article reviewed the published papers on ACT with focus on sustainability; compliance; and diagnosis. ACTs are costly; but highly effective. Their scaling up is the most cost effective malaria intervention currently available. Most countries rely heavily on the Global Fund for their scaling up. AL has a short shelf life; a complicated six-dose regimen that requires intake with fat to ensure sufficient bioavailability. High rates of adherence have been reported. Use of parasitic diagnosis is advocated to ensure rational use. Parasitic diagnostics like rapid test and microscopy are currently inadequate. The majority of malaria cases may continue to be diagnosed clinically leading to over prescription of drugs. ACTs are currently not available at the community level for home based management of malaria. Issues related to safety and rational use need to be addressed before their use in the informal health sector like community drug sellers and community health workers. The majority of malaria cases at the community level could go untreated or continue to be treated using less effective drugs. We conclude that ACTs are highly effective. A major challenge is ensuring rational use and access at the household level. It is hoped that addressing these issues will increase the likelihood that ACT achieves its intended goals of reducing morbidity and mortality due to malaria; and delaying the onset of drug resistance

The efficacy of inhibitors involved in spermidine metabolism in Plasmodium falciparum, Anopheles stephensi and Trypanosoma evansi.

In the present study, we have tested the effect of different polyamine inhibitors of the spermidine metabolizing enzymes deoxyhypusine synthase and homospermidine synthase in different chloroquine resistant Plasmodium falciparum strains, in the mosquito Anopheles stephensi (Diptera: Culicidae) and in a Trypanosoma evansi clone I from strain STIB 806 K China. Recent experiments have shown that agmatine is a growth inhibitor of the malaria parasite P. falciparum (Kaiser et al. 2001) in vitro. A comparison of agmatine efficacy with the new antimalarials artemisinin, triclosan and conventional chloroquine showed similar or even better results on the basis of growth inhibition and the reduction of developmental forms. However, no effect of triclosan or agmatine was observed at the ribonucleic acid level. In a second set of experiments, we tested the effect of 1,7-diaminoheptane and agmatine on oocyst formation in A. stephensi after infection with Plasmodium yoelii. Agmatine had an antisporozoite effect since 1,000 microM led to a 59.5% inhibition of oocysts. A much weaker inhibitor of oocyst formation was 1,7-diaminoheptane. The most effective in in vitro inhibition of T. evansi was dicyclohexylamine, an inhibitor of spermidine biosynthesis with an IC(50 ) value of 47.44 microM and the deoxyhypusine inhibitor 1,7-diaminoheptane with an IC(50) value of 47.80 microM. However, both drugs were ineffective in in vivo experiments in a Trypanosoma mouse model. Two different spermidine analogues, 1,8-diaminooctane and 1,3-diaminopropane with IC(50) values of 171 microM and 181.37 microM, respectively, were moderate inhibitors in vitro and ineffective in vivo.

The application of PCR-ELISA to the detection of Trypanosoma brucei and T. vivax infections in livestock.

Teneral tsetse flies infected with either Trypanosoma brucei or T. vivax were fed on healthy cattle. Blood samples collected daily from the cattle were examined by microscopy for the presence of trypanosomes, in thick smear, thin smear and in the buffy coat (BC). All the cattle fed upon by infected tsetse developed a fluctuating parasitaemia. DNA was extracted from the blood of these cattle and subjected to polymerase chain reaction (PCR) using oligonucleotide primers specific for T. brucei or T. vivax. The PCR products unique to either T. brucei or T. vivax were identified following amplification of DNA from the blood samples of infected cattle, whereas none was detectable in the DNA from the blood of the cattle exposed to non-infected teneral tsetse. In a concurrent set of experiments, one of the oligonucleotide primers in each pair was biotinylated for use in PCR-ELISA to examine all the blood samples with this assay. Both the PCR and the PCR-ELISA revealed trypanosome DNA in 85% of blood samples serially collected from the cattle experimentally infected with T. brucei. In contrast, the parasitological assays showed trypanosomes in only 21% of the samples. In the blood samples from cattle experimentally infected with T. vivax, PCR and PCR-ELISA revealed trypanosome DNA in 93 and 94%, respectively. Microscopy revealed parasites in only 63% of the BCs prepared from these cattle. Neither PCR nor PCR-ELISA detected any trypanosome DNA in blood samples collected from the animals in the trypanosome-free areas. However, both assays revealed the presence of trypanosome DNA in a number of blood samples from cattle in trypanosomosis-endemic areas.

Sequence diversity and virulence in Zea mays of Maize streak virus isolates.

Full genomic sequences were determined for 12 Maize streak virus (MSV) isolates obtained from Zea mays and wild grass species. These and 10 other publicly available full-length sequences were used to classify a total of 66 additional MSV isolates that had been characterized by PCR-restriction fragment length polymorphism and/or partial nucleotide sequence analysis. A description is given of the host and geographical distribution of the MSV strain and subtype groupings identified. The relationship between the genotypes of 21 fully sequenced virus isolates and their virulence in differentially MSV-resistant Z. mays genotypes was examined. Within the only MSV strain grouping that produced severe symptoms in maize, highly virulent and widely distributed genotypes were identified that are likely to pose the most serious threat to maize production in Africa. Evidence is presented that certain of the isolates investigated may be the products of either intra- or interspecific recombination.

Comparative sensitivity of dot-ELISA, PCR and dissection method for the detection of trypanosome infections in tsetse flies (Diptera: glossinidae).

A visually read dot-enzyme linked immunosorbent assay (dot-ELISA) developed for the detection of trypanosomes in tsetse flies (Glossina spp.) was evaluated in the laboratory and under field conditions. In the evaluation, the fly dissection method was used as a standard technique and compared to the polymerase chain reaction (PCR). In laboratory studies, 133 and 126 tsetse flies were experimentally infected with different stocks of Trypanosoma brucei and T. congolense, respectively. Twenty-five days after infection, the flies were dissected and tested for the presence of trypanosomes using dot-ELISA and PCR. Dot-ELISA detected 98.4% of T. brucei and 94% of T. congolense infections in tsetse midguts, while PCR detected 97.6% of T. brucei and 96% of T. congolense tsetse midgut samples. For field evaluation of dot-ELISA, 700 tsetse flies were caught and screened for trypanosome infections by dissection. Seven of these (1%) had trypomastigotes in the midgut, 23 (3.3%) in the proboscis and none had trypanosomes in the salivary glands. All the flies with midgut infections also had trypanosomes in their proboscides. Five of the seven flies (71.4%) with midgut infections revealed by dissection, were also positive for T. congolense by the dot-ELISA and PCR techniques. Dot-ELISA detected T. congolense infections in an additional 86 (12.4%) of the 700 flies dissected. Of the 23 infections in the proboscis, 16 were T. vivax. Dot-ELISA detected 13 of the 16 (81%) while PCR detected 15 of 16 (94%) T. vivax infections. No T. brucei infection was detected by any of the methods in all the 700 tsetse flies examined. The results obtained from both the laboratory and field studies indicate that the dot-ELISA and PCR techniques are sensitive and species-specific in revealing trypanosome infections in tsetse flies. While dot-ELISA required a single test to detect T. congolense, several primer pairs were needed for PCR. The potential use of dot-ELISA as a tool for studying the epidemiology of trypanosomosis, while considering its field applicability and relatively lower cost is discussed.

Sensitive and specific detection of Trypanosoma vivax using the polymerase chain reaction.

The nucleic acid probes that are currently in use detect and distinguish Trypanosoma vivax parasites according to their geographic origin. To eliminate the need for using multiple DNA probes, a study was conducted to evaluate the suitability of a tandemly reiterated sequence which encodes a T. vivax diagnostic antigen as a single probe for detection of this parasite. The antigen is recognized by monoclonal antibody Tv27 currently employed in antigen detection ELISA (Ag-ELISA). A genomic clone which contained a tetramer of the 832-bp cDNA sequence was isolated and shown to be more sensitive than the monomer. Oligonucleotide primers were designed based on the nucleotide sequence of the 832-bp cDNA insert and used in amplifying DNA sequences from the blood of cattle infected with T. vivax isolates from West Africa, Kenya, and South America. The polymerase chain reaction (PCR) product of approximately 400 bp was obtained by amplification of DNA from all the isolates studied. The oligonucleotide primers also amplified DNA sequences in T. vivax-infected tsetse flies. Subsequently, PCR was evaluated for its capacity to detect T. vivax DNA in the blood of three animals experimentally infected with the parasite. T. vivax DNA was detectable in the blood of infected animals as early as 5 days post-infection. Blood and serum samples from the three cattle and from six other infected animals were also examined for the presence of trypanosomes and T. vivax-specific diagnostic antigen. Trypanosomes appeared in the blood 7-12 days post-challenge, while the antigenemia was evident on Days 5-20 of infection. Analysis of the data obtained in the three animals during the course of infection revealed that the buffy coat technique, Ag-ELISA, and PCR revealed infection in 42, 55, and 75% of the blood samples, respectively. PCR amplification of genomic DNA of T. vivax is thus superior to the Ag-ELISA in the detection of T. vivax. More importantly, both the T. vivax diagnostic antigen and the gene encoding it are detectable in all the T. vivax isolates examined from diverse areas of Africa and South America.

Comparative sensitivity of antigen-detection enzyme immunosorbent assay and the microhaematocrit centrifugation technique in the diagnosis of Trypanosoma brucei infections in cattle.

Four Boran cattle were infected with Trypanosoma brucei using Glossina morsitans centralis and were left untreated throughout the experimental period of 18 months. During this period, sequential blood samples were collected and examined for the presence of antitrypanosome antibodies and their antigens. Using the buffy coat technique (BCT), trypanosomes were detected in 38 (16.3%) of the 233 blood samples. Unlike the BCT, antigen-detection enzyme-linked immunosorbent assay (Ag-ELISA) diagnosed infections in 189 (81.1%) of the blood samples. These results were supported by the presence of antitrypanosome antibodies in the same samples. Thus Ag-ELISA was 5.5 times more sensitive than the BCT. Towards the end of the observation period, G.m. centralis tsetse were fed on the aparasitaemic cattle to determine whether they still harboured the infection as the persistent antigenaemia seemed to suggest. Bloodmeals from the four cattle were infective to tsetse, thus emphasising the importance of Ag-ELISA in diagnosis of sub-patent infections.