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M Desquesnes

Publications and source records attributed to M Desquesnes.

At least 19 recordsLinked to original sources
PubMed2006

Biting flies and Trypanosoma vivax infection in three highland districts bordering lake Tana, Ethiopia.

An epidemiological study was conducted to determine the prevalence of trypanosomosis in cattle, small ruminants and Equidae, and to identify biting flies; potential mechanical vectors of trypanosomes in the three districts of Bahir Dar Zuria, Dembia and Fogera, bordering lake Tana, Ethiopia. About 1509 cattle, 798 small ruminants and 749 Equidae were bled for the prevalence study using the buffy-coat method and the measurement of the hematocrit value. Sixty-six NGU and 20 monoconical traps were deployed for the fly survey. The results indicated the presence of trypanosomes in 6.1% (92/1509) of the cattle with a maximum during the late rainy season (9.6%) than the early dry season (3.6%) at Fogera district. Prevalence at the district level varied from 4% to 9.6%. Only one sheep (1/122) and one goat (1/676) were found positive for T. vivax-like trypanosomes and none of the Equidae was positive. All the trypanosomes encountered in cattle belong to the single species of T. vivax. The PCV was negatively associated with detection of T. vivax (21.6% in infected versus 25.4% in non-infected cattle). A total of 55,398 biting flies were caught of which 49,353 (89.08%) belong to Stomoxys, 4715 (8.51%) to horse flies and 1330 (2.4%) to Chrysops species. There was no tsetse fly. Species identification has indicated the presence of Atylotus agrestis, Chrysops streptobalia, Stomoxys calcitrans, S. nigra, S. pulla, S. pallida, S. sitiens, S. taeniata, S. uruma, Haematopota lasiops and Hippobosca variegata. The overall apparent density was 214.7flies/trap/day. Seasonal comparison showed higher fly catches in the late rainy season than the early dry season. This study indicated that T. vivax infections culminate in cattle at the same time as mechanical vectors such as Stomoxys sp. and Atylotus agrestis. Therefore, attention towards T. vivax infection in cattle is essential to control the impact of the disease on productivity. A further study on biting flies is recommended.

Animals↗
PubMed2006

The application of PCR-ELISA to the detection of Trypanosoma congolense type savannah (TCS) in bovine blood samples.

PCR-ELISA was set up to detect strains of Trypanosoma congolense type savannah (TCS) in field samples of buffy coats. Results of PCR-ELISA and PCR were compared and the effectiveness of both techniques was also compared with the Murray's method for the detection of TCS in 257 bovine buffy coats. The PCR products were labelled with digoxigenin (DIG-dUTP) during amplification cycles of the repetitive satellite DNA. A biotinylated DNA capture probe was used to detect the PCR products by ELISA in streptavidin coated microplates. Both the PCR-ELISA and PCR were more sensitive and more specific than the Murray's method. Of the 257 buffy coats analysed by the three techniques, PCR-ELISA and PCR detected TCS in 98 and 97 buffy coats respectively, whereas the Murray's method detected only 39 samples. PCR-ELISA and PCR had almost the same sensitivity and specificity. PCR-ELISA and PCR respectively detected TCS in 39.2% and 38.6% in all the 334 samples analysed by both techniques in this study.

Animals↗
PubMed2005

A longitudinal epidemiological survey of bovine trypanosomosis and its vectors in the White Volta river basin of Northern Ghana.

A longitudinal epidemiological survey of bovine trypanosomosis and its vectors was carried out in the Volta river basin of Northern Ghana to determine the relationship between cattle management and the incidence of bovine trypanosomosis. Two groups of sentinel cattle under different systems of management, classified as "fully-sedentary" and "partially-sedentary" (depending on the type of management) were followed over a 1-year period starting from March 2003 onwards. Cattle were screened at intervals of 3 months using the buffy coat technique (BCT). Buffy coat specimen from animals that were positive for the BCT and those that were negative, but with a packed cell volume (PCV) of less than 21% were further tested using the polymerase chain reaction (PCR). Plasma from all animals were tested for antibody using the indirect antibody enzyme-linked immunosorbent assay (ELISA). Trypanosomosis challenge was determined in tandem with the epidemiological survey with watering sites of sentinel cattle being the foci of interest. The parasitological prevalence at the start of the survey was higher in the fully-sedentary group (9%) than in the partially-sedentary group (3%). In subsequent visits, however, the parasitological incidence was consistently higher in the partially-sedentary group than in the fully-sedentary group. The mean seroprevalence (ELISA) of both groups increased from 3% in March to 54% in December. Statistical analysis of the serological results using a random effect logistic regression, showed a significant difference in incidence of bovine trypanosomosis between the two groups. There was also a significant effect of time. The influence of cattle herding on host-vector-parasite interface and its consequence on the incidence of trypanosomosis are discussed.

Animal Husbandry↗
PubMed2004

A cross-sectional epidemiological survey of bovine trypanosomosis and its vectors in the Savelugu and West Mamprusi districts of northern Ghana.

The epidemiology of bovine trypanosomosis was investigated in two districts (Savelugu and West Mamprusi) of Northern Ghana with different land use and environmental characteristics. The land use intensity and environmental change was suspected to be higher in the Savelugu District. A cross-sectional entomological survey conducted along the White Volta river and its tributaries confirmed the presence of only Glossina palpalis gambiensis and G. tachinoides. The challenge index as measured by the product of tsetse density and tsetse infection rate was much higher in the West Mamprusi (19.6) than in the Savelugu district (4.7). A total of 1013 cattle (508 in Savelugu and 505 in West Mamprusi) were bled from a random selection of 16 villages in the Savelugu District and 13 villages in the West Mamprusi District. Blood samples were examined for trypanosomes by the buffy coat technique (BCT). Blood samples that were positive in the BCT or negative in the BCT but with packed cell volume (PCV) values below 21 were further tested with a polymerase chain reaction for trypanosomal DNA. Plasma samples of all cattle were serologically tested with an indirect ELISA for trypanosomal antibodies. The parasitological and serological prevalence of bovine trypanosomoses was significantly higher in West Mamprusi (16 and 53%, respectively) than in Savelugu District (8 and 24%, respectively). An evaluation of animal health at the village herd level, using PCV as an index of anaemia, provided various epidemiological scenarios prevalent in the entire study area.

Anemia↗
PubMed2002

Applications of PCR-based tools for detection and identification of animal trypanosomes: a review and perspectives.

This paper aims to review the applications of the polymerase chain reaction (PCR) for the detection and identification of trypanosomes in animals. The diagnosis of trypanosomes, initially based on microscopic observations and the host range of the parasites, has been improved, since the 1980s, by DNA-based identification. These diagnostic techniques evolved successively through DNA probing, PCR associated to DNA probing, and currently to PCR alone. Several DNA sequences have been investigated as possible targets for diagnosis, especially multi-copy genes such as mini-exon, kinetoplastid mini-circles, etc., but the most favoured target is the nuclear satellite DNA of mini-chromosomes, which presents the advantages, and the drawbacks, of highly repetitive short sequences (120-600 bp). Several levels of specificity have been achieved from sub-genus to species, sub-species and even types. Random priming of trypanosome DNA has even allowed "isolate specific" identification. Other work based on microsatellite sequences has provided markers for population genetic studies. For regular diagnosis, the sensitivity of PCR has increased with the advancement of technologies for sample preparation, to reach a level of 1 trypanosome/ml of blood, which has brought to field samples a sensitivity two to three times higher than microscopic observation of the buffy coat. Similarly, PCR has allowed an increase in the specificity and sensitivity of diagnosis in vectors such as tsetse flies. However, because of the diversity of Trypanosoma species potentially present in a single host, PCR diagnosis carried out on host material requires several PCR reactions; for example, in cattle, up to five reactions per sample may be required. Research is now focusing on a diagnosis based on the amplification of the internal transcribed spacer-1 (ITS-1) of ribosomal DNA which presents the advantages of being a multi-copy locus (100-200), having a small size (300-800 bp), which varies from one taxon to another but is conserved in size in a given taxon. This may lead to the development of a multi-species-specific diagnostic protocol using a single PCR. By reducing the cost of the PCR diagnosis, this technique would allow a greater number of field samples to be tested in epidemiological studies and/or would increase the variety of Trypanosoma species that could be detected. Further investigations are required to develop and optimise multi-species-specific diagnostic tools for trypanosomes, which could also serve as a model for such tools in other pathogens.

Animals↗
PubMed2002

Comparative pathogenicity of three genetically distinct types of Trypanosoma congolense in cattle: clinical observations and haematological changes.

The pathology of African bovine trypanosomosis was compared in Zebu cattle subcutaneously inoculated with three clones of trypanosomes corresponding to the three genetically distinct types of Trypanosoma congolense; savannah-type, west African riverine/forest-type and kilifi-type. All inoculated animals became parasitaemic between 7 and 11 days post-infection (dpi). The savannah-type showed consistently higher levels of parasitaemia and lower packed red cell volume percentages and leukocyte counts than the other two types. The syndrome was also more severe in the savannah-type and led inexorably to death between 29 and 54 dpi while animals with the forest or the kilifi-types recovered from earlier symptoms and haematological alterations after 3 months of infection. By the end of the experiment, the animals self-cured from the forest-type infection and the kilifi-type passed under control. The results of the present study indicated clear difference in pathogenicity between the three types of T. congolense; the savannah-type was virulent while the forest-type was of low pathogenicity and the kilifi-type was non-pathogenic.

Animals↗
PubMed2002

Comparative pathogenicity of three genetically distinct Trypanosoma congolense-types in inbred Balb/c mice.

Inbred Balb/c mice were infected with three clones of Trypanosoma congolense (Sam.28.1, Dind.3.1 and K60.1A) corresponding, respectively, to the three genetically distinct types (savannah, forest and kilifi) defined within this species, for the purpose of comparing their pathogenicity for a better understanding of the epidemiology of African trypanosomosis. Another clone of savannah type, IL 3000, was also tested simultaneously to study a probable strain variation. Both the clones of savannah type were found of extreme virulence with loss of appetite, rough hair, rapid respiration, lethargy, and all mice died within a week. Parasitaemias evolved rapidly to the first peak by day 3-5 post-inoculation without any remission and the course of disease was correlated positively with the prepatent period. The clones of the forest type and the kilifi type were of low virulence with chronic infection and symptoms progressively less patent throughout the infection; only one mouse died in each experimental group.

Animals↗
PubMed2001

Detection and identification of Trypanosoma of African livestock through a single PCR based on internal transcribed spacer 1 of rDNA.

Primers hybridising with the rDNA cistron have previously been evaluated for PCR diagnosis specific for kinetoplastids, and shown to detect and differentiate the Trypanosoma brucei complex and Trypanosoma cruzi. Kin1 and Kin2 primers, amplifying internal transcribed spacer 1, were subsequently evaluated for the diagnosis of African livestock trypanosomosis. Based on the size of the PCR products obtained, Kin primers allowed detection and identification of three Trypanosoma congolense types (savannah, forest and Kenya Coast), with distinction among themselves and from the subgenus Trypanozoon (T. brucei spp., Trypanosoma evansi and Trypanosoma equiperdum), Trypanosoma vivax, Trypanosoma simiae and Trypanosoma theileri. These primers were shown to be suitable for the sensitive and type-specific diagnosis of African livestock trypanosome isolates through a single PCR even in the case of multi-taxa samples. With field samples (buffy-coat from cattle blood) sensitivity was close to the sensitivity observed in single reactions with the classical specific primers for the Trypanozoon subgenus and T. congolense-type savannah, but was lower for detection of T. vivax. Additional reaction, improvement of DNA preparation, and/or new primers design are necessary to improve the sensitivity for detection of T. vivax in field samples. However, these primers are suitable for isolate typing through a single PCR.

Animals↗
PubMed2001

Validation of a polymerase chain reaction assay for monitoring the therapeutic efficacy of diminazene aceturate in trypanosome-infected sheep.

The diagnostic performance of a polymerase chain reaction assay (PCR) for monitoring the effectiveness of aceturate diminazene treatment was compared with those of an antibody-detection ELISA test and the buffy-coat technique using sheep experimentally infected with either savannah-type or forest-type Trypanosoma congolense or T. vivax. Within the period of infection, the PCR using specific savannah-type T. congolense primers showed a significant higher diagnostic sensitivity (p<0.05) than the buffy-coat technique. Both techniques gave closed results for detecting forest-type T. congolense or T. vivax infections. Following trypanocidal treatment, the PCR showed that specific product disappeared definitively 1 or 2 days later in animals in which a decrease of the antibody level and a significant improvement of the red packed cell volume were observed. The occurrence of relapse infection was detected by the PCR in one animal infected by T. vivax on day 19 post-treatment and confirmed by the persistence and increasing antibody level whereas the buffy-coat technique detected parasites 42 days later. Then, the PCR signals remained positive on several occasions while parasitaemia was detected only two times.The application of PCR combined with the antibody detection appeared to provide a useful tool as compared to the buffy-coat technique for monitoring the effectiveness of trypanocidal treatment.

Animals↗
PubMed2001

The analysis of the cross-reactions occurring in antibody-ELISA for the detection of trypanosomes can improve identification of the parasite species involved.

In Africa, the main pathogenic trypanosomes of livestock are Trypanosoma vivax, T. congolense and T. brucei. The geographical distributions and hosts of these three species are very similar. As they differ markedly in pathogenicity and epidemiology, however, a species-specific serological test for infection would be very useful for epidemiological studies. The antibody-ELISA (Ab-ELISA) that have been developed for detecting the Trypanosoma spp. most commonly infecting livestock give satisfactory sensitivity and genus specificity. Unfortunately, they are not species-specific because of strong cross-reactions between the pathogenic Trypanosoma spp. In the present study, carried out in Burkina Faso, the results of standardized Ab-ELISA for T. vivax, T. brucei or T. congolense were compared using 1288 plasma samples from sheep experimentally infected with T. vivax, T. evansi and/or T. congolense. If the results were interpreted, as usual, only using a positivity threshold (PT), the strong cross-reactions observed led to a mean species-specificity of < 30%. However, analysis of the reactions observed in the three types of Ab-ELISA revealed that the homologous reactions were stronger than the heterologous for almost all of the single and mixed infections (98.3% and 99.0%, respectively). In monospecific infections exceeding the PT study of the positivity score produced in each of the three types of Ab-ELISA increased species-specificity to > 96%. It therefore appears that comparison of the strengths of the reactions seen in Ab-ELISA could greatly improve sero-epidemiological surveys of trypanosome infections in domestic ruminants, although the technique remains to be evaluated in experimentally infected cattle.

Animals↗
PubMed1997

Evaluation of a simple PCR technique for the diagnosis of Trypanosoma vivax infection in the serum of cattle in comparison to parasitological techniques and antigen-enzyme-linked immuno sorbent assay.

Polymerase chain reaction (PCR) with specific oligonucleotides for the amplification of Trypanosoma vivax DNA has been developed by Masiga et al. (1992) to detect the presence of T. vivax DNA in biting flies. The aim of this experiment was to evaluate the efficacy of this technique when applied directly on cattle serum, without DNA purification, to detect infection. The sensitivity of this PCR technique was compared with parasitological techniques, namely haematocrit centrifuge technique (HCT) and buffy coat method (BCM), and with the antigen-enzyme-linked immunosorbent assay (Ag-ELISA) for T. vivax developed by Nantulya and Lindqvist (1989). Blood and serum samples were collected from four calves experimentally infected with a stock of T. vivax from French Guyana (IL4007). During the first 51 days of infection, a total of 164 samples were collected and processed using the four tests. Mean percentages of positive results were 68% with HCT, 59% with BCM, 4% with Ag-ELISA and 64% with PCR. Parasitological and PCR techniques yielded approximately the same sensitivities. PCR was able to detect active infection in serum samples when parasitaemia was over 10(3) trypanosomes/ml. With this isolate of T. vivax the Ag-ELISA was not found to be sensitive enough to be used as a diagnostic tool. The sensitivity of this PCR technique is not greater than parasitological techniques but it allows delayed processing of the samples and gives a highly species-specific diagnosis. This simple PCR technique should be evaluated for field diagnosis because it makes retrospective epidemiological survey using serum banks possible. Moreover, it can be substituted to parasitological techniques when immediate examination is not feasible.

Animals↗
PubMed1997

[International and regional standardization of immunoenzyme tests: methods, concerns and limitations].

Numerous attempts have been made to standardise immuno-enzyme techniques (enzyme-linked immunosorbent assay: ELISA) used for the diagnosis of infectious diseases, in order to improve the reproducibility of the tests, expression of results, choice of a positive threshold, and selection of reference samples. The international standardisation of reagents and test protocols appears essential for quality control and the comparison of results between laboratories, but the interpretation of results can encounter major differences depending on the geographical sector under study. Based on these studies, and in the light of a model indirect ELISA for detecting antibodies against Trypanosoma vivax in cattle, the author proposes the international standardisation of reagents, test protocol, and the expression of results of ELISA using international reference samples. For local standardisation, the following proposals are made: sampling of representative local populations. Establishment of the distribution patterns of infected and uninfected local populations. Selection of representative controls from local populations (secondary reference samples). Expression of test results in comparison with these controls. Establishment of internal quality control based on the response of controls. Determination of a positive threshold, in accordance with the requirements of the user. Adaptation of the positive threshold according to the prevalence observed in the geographical sector under study.

Animals↗
PubMed1996

TRYPNET. New hemoparasite information network.

Although Guyana, Suriname, and French Guiana share borders and climatic and geographic similarities, the countries have maintained little contact, due to language, political, and administrative differences. In 1993, two international organizations involved in the improvement of animal health, the Inter-American Institute for Cooperation on Agriculture (IICA) and CIRAD-EMVT (Centre de Cooperation Internationale en Recherche Agronomique pour le Developpement-Elevage et Medecine Veterinaire des Pays Tropicaux), jointly developed a collaborative project between the veterinary services of the three countries entitled "Hemoparasite Network for the Guianas." This project seeks to pool livestock, laboratory, and technical resources between the three countries in order to generate and exchange information on hemoparasites of livestock. A Hemoparasite Reference Laboratory for the Guianas has been created at the CIRAD-EMVT laboratory in Cayenne, French Guiana. Besides processing ruminant serum samples from the three countries, specialists from this organization conduct training in hemoparasite diagnostic techniques for laboratory personnel from Guyana and Suriname. A large-scale epidemiologic study of hemoparasites of cattle in the three countries is under way, to determine the prevalence, distribution, and clinical and economic significance of hemoparasites in the three countries, particularly Trypanosoma vivax and T. evansi. Preliminary results are presented and discussed. A Hemoparasite Information Network (TRYPNET) has been initiated, including a quarterly hemoparasite newsletter (TRYPNEWS), published in English and Spanish and disseminated to researchers in the Americas, Europe, and Africa. In 1995/96, it is proposed to expand the network's scope to include Venezuela and Brazil.

Abattoirs↗
PubMed1996

Evaluation of three antigen detection tests (monoclonal trapping ELISA) for African trypanosomes, with an isolate of Trypanosoma vivax from French Guyana.

Preliminary studies in French Guyana with sheep experimentally infected with a local isolate of Trypanosoma vivax tended to show poor sensitivity and/or specificity of the monoclonal antibodies used in kits for the antigen-detection (Ag) ELISA for T. vivax, T. brucei, and T. congolense. To reevaluate these kits, 4 calves were infected at ILRAD, Nairobi, Kenya, with the same isolate. Blood samples were taken daily for 51 days, and examined directly on blood smears and buffy coat, and using Ag-ELISA for the three species. For the 4 calves, on 158 tests performed over the first 51 days of infection, the percentages of positive results were 66% on buffy coat; on Ag-ELISA 3.8% for T. vivax, 4.4% for T. brucei, and 3.1% for T. congolense. Blood smears showed only T. vivax. These results confirm those previously obtained in French Guyana: the test for T. vivax (at least in the initial stage) shows a very low sensitivity, far below that of parasitological techniques, and the specificity of the T. brucei and T. congolense tests is low. Certain surprising results obtained in Africa might also be due to a poor sensitivity and specificity of the monoclonals used. As ELISA is the technic of choice for epidemiological surveys, and antigen detection a logical way to confirm whether an animal is actively infected by trypanosomes, the Ag-ELISA remains a necessary tool for epidemiological surveys of trypanosomes; new monoclonals are required to develop more specific and sensitive tests.

Animals↗
PubMed1996

[Evaluation of sensitivity of PCR for detecting DNA of Trypanosoma vivax with several methods of blood sample preparations].

Parasitological techniques show a low sensitivity for diagnosis of active infections with Trypanosoma sp. in livestock, particularly in the case of chronic infections. T. vivax antigen detection through antigen-ELISA developed by Nantulya and Lindqvist (1989) is not sensitive and specific enough for infection diagnosis. T. vivax DNA detection through polymerase chain reaction (PCR) using the oligonucleotides developed by MASIGA et coll. (1992) appears to be an alternative for a specific diagnosis of T. vivax active infections in livestock. Twenty-two blood samples containing known numbers of T. vivax/ml, ranging from 1 to 1767, were prepared by dilution of T. vivax infected sheep blood into blood from a non infected sheep. PCR sensitivity was evaluated in several types of blood sample preparations: crude heparinized blood, plasma, lysed blood, buffy coat from haematocrit capillary tubes, pellet from plasma centrifugation, and DNA purified with an ion exchange resin commercial kit. Crude heparinized blood almost always inhibited PCR. Sensitivity of PCR with plasma and lysed blood was low, around 450 parasites/ml. PCR on buffy coat was more sensitive, but PCR products were sometimes little visible. Pellet of plasma centrifugation is an original, fast and economic preparation, whose PCR products are highly visible and which presents a high sensitivity: one hundred percent of the samples were positive when the parasitaemia was over 9 parasites/ml. DNA purification is slightly more time consuming and expensive, since it requires several manipulations and the use of a commercial kit, but it appears to be the most sensitive technique among those investigated: one hundred percent of the samples were positive when the parasitaemia was over 2 parasites/ml; however, PCR products were sometimes difficult to interpret. These last two techniques are recommended for a sensitive and species-specific diagnosis of active infections of livestock with T. vivax. These techniques should be evaluated for other pathogenic trypanosome species of livestock.

Animals↗
PubMed1996

[Evaluation of the sensitivity of the Woo test for the detection of Trypanosoma vivax].

The haematocrit centrifuge technique (HCT), or Woo test, is the technique most commonly used for diagnosis of animal trypanosomosis, but its sensitivity is not well defined. Depending on the authors, the sensitivity of the Murray technique (dark' ground buffy coat method, or DG/BCM) is higher, equal or lower than that of the Woo test for the detection of Trypanosoma vivax. Most authors have compared particular techniques relatively to other techniques, rather than attempting to measure the sensitivity of the tests in relation to a fixed reference. The relative sensitivity of particular tests appears to vary between technicians. The aim of the present study was to measure the sensitivity of the Woo test for French Guiana T. vivax detection, using blood samples with pre-determined levels of parasitaemia, ranging from 1 to 1767 parasites/ml, that were prepared by mixing infected ovine blood with non infected ovine blood. A simple technique is described for the enumeration of parasites in blood. The mean positivity level of the Woo test in sheep was about 200 +/- 110 T. vivax/ml. The sensitivity of the test was 100% above 700 parasites/ml, about 80% between 300 and 700, 50% between 60 and 300, and was negligible below 60 parasites/ml. Parameters are provided to estimate parasitaemia based on the number of parasites observed between slide and cover slip (parasitaemia > 2000) or in the capillary tube (parasitaemia < 2000). Sensitivity of the techniques for detection of active infection could be evaluated in comparison with fixed values such as known parasitaemiae, artificially created, as described here.

Animals↗
PubMed1995

[Comparison of the sensitivity of the Woo test and a test for detecting antigens to Trypanosoma vivax in 2 sheep experimentally infected with a Guyanese strain of the parasite].

A trapping ELISA for the detection of circulating antigens of Trypanosoma vivax with a specific monoclonal antibody was developed by Nantulya and Lindqvist in 1989. With the African strains tested, its sensitivity proved very high. Using reagents supplied by ILRI, the sensitivity of this test was compared with that of the Woo test in two sheep experimentally infected with a Guyanese strain of T. vivax. Blind tests carried out at CIRDES and ILRI confirmed the results obtained in French Guiana. The animals were bled regularly during the first 130 and 285 days of infection. Whatever the period of infection ans whether there was patent parasitaemia or not, the mean sensitivity of the ELISA test was very low: 2.1% of positive results, far below the Woo test's 54% of positive results. Associating the two techniques did not improve the sensitivity. The mean optical densities recorded during these long periods of infection (0.010 +/- 0.004 and 0.012 +/- 0.002) are so close to the sensitivity threshold of the ELISA readers that they cannot be proposed as a cut-off threshold to improve the sensitivity of the test. A complementary study of the sensitivity of this test is in progress at ILRI. As already observed in Burkina Faso and The Gambia, this poor sensitivity may greatly affect the results of the epidemiological surveys being carried out with these reagents in Africa. New monoclonal antibodies must be developed to produce a test for T. vivax antigens with more satisfactory sensitivity.

Animals↗