[Production of sporozoites of human Plasmodium in Bobo-Dioulasso (Burkina Faso)]. / Production de sporozoïtes de Plasmodium humains à Bobo-Dioulasso (Burkina Faso).

Mass production of P. falciparum sporozoites requires an intensive production of mosquitoes and an experimental infection of this vector. A gambiae is the main vector of P. falciparum, and P. ovale in Burkina. In the first part we study 3 factors interfering with breeding and experimental infection of this anopheline species. They are: insectarium temperature, pattern and rhythm of blood feeding. In the second part, we study "parasite", "host" and "mosquito" parameters which interfere with the yield of experimental infections. The increase of temperature promotes growth of parasite, but it also enhances bacterial and mycosal pollution; and so, it reduces survival of mosquitoes. Natural feeding on rabbit gives a better laying and a larger blood meal than experimental feeding through an artificial membrane. Meanwhile, it requires a rabbit rearing. We finally adopted the following compromise: the two first blood meals are taken on rabbit, the next are taken on membrane covered devices. It is necessary to give non-parous females two consecutive blood meals that allow the first gonotrophic cycle. The optimal time is on the 3-4 day after emergence. For the mosquitoes reserved for experimental infections, it is necessary to infect them very soon to have more surviving females at the end of the sporogonic cycle. These mosquitoes receive their first and single blood meal an day 2 and can be infected on day 5. There is a positive correlation between the intensity of egg production and the mosquito mortality. Although blood meals are important for parasite development, we prefer to give only one blood meal on day 6 after infection to promote the vector survival rather than maturity of the parasite. This study has allowed to standardize breeding conditions and to obtain regularly 10,000 mosquitoes per day. The infection rate depends on parasite factors. P. falciparum gametocytes may be infectious to mosquitoes at densities as low as 5/mm3 of blood. Maximum infectiousness is reached between 50 to 450/mm3. At higher densities, infectiousness of gametocytes seems to decrease. In natural conditions, sex-ratio and maturity of gametocytes do not appear to interfer with infectiousness. The infection rate also depends on host parameters. They are yet unknown. We saw a specific phagocytosis of sexual stages in mosquito midgut, after infection with a high density gametocyte carrier, without any infected mosquito. On the other hanb, infectiousness of gametocytes seems to decrease with age of the gametocyte carrier. The role of immunity inmodulating the infectivity of gametocytes cannot be excluded. Finally, the infection rate depends on mosquito factors.(ABSTRACT TRUNCATED AT 400 WORDS)

Trypanosoma brucei: polyamine oxidase mediated trypanolytic activity in the serum of naturally resistant cattle.

Trypanosoma brucei brucei are lysed when incubated in vitro in a mixture of bovine serum and polyamine. Normal bovine serum alone or polyamine alone does not show any trypanocidal activity. The bovine serum in the mixture can be replaced by purified polyamine oxidase, and addition of polyamine oxidase inhibitors blocks trypanolysis. Using this in vitro lysis test, it is shown that West African cattle which are resistant naturally to trypanosomiasis have a higher trypanolytic activity in their serum than do trypanosensitive cattle (P less than 10(-5]. Seric trypanolytic activity of individual animals remains stable when tested over a period of 18 months; moreover, it is not modified by trypanosome infection. Higher levels of seric polyamine oxidase in resistant cattle were demonstrated also by enzymatic analysis. The factors responsible for trypanolysis have been analyzed. Oxidation of spermidine by polyamine oxidase leads to the production of unstable aldehydes, acrolein, ammonia, O2-, HO, and H2O2. Acrolein and H2O2 show strong trypanolytic activity while the other products do not appear to be toxic for trypanosomes. The physiological importance of polyamine oxidase mediated trypanolysis is unclear; even at peak parasitemia in cattle (10(7) organisms/ml) it can be calculated that trypanosomes would not release enough spermidine for the generation of sufficient quantities of toxic degradation products. Additional polyamines could be released in serum from tissues damaged as a result of the infection.

[Comparative value of ELISA technique and immunofluorescence for the detection in the foci of human African trypanosomiasis]. / Intéret de la technique ELISA pour le dépistage dans les foyers de trypanosomiase humaine africaine. Comparaison avec l'immunofluorescence.

As the parasitological diagnosis method consisting in the detection of the parasite in people suffering from sleeping sickness did not prove entirely reliable, the authors have tested a new immunoenzymatic diagnosis method called ELISA. 41 sera from clinical suspects have been tested (parasite having been found in 16 of them). Positive and negative levels have been tested by comparison with indirect immunofluorescence. The following results, given in optical density, have been obtained: negative cases less than 36 less than or equal to uncertain cases less than or equal to 40 less than positive cases. When using these date, correlation with immunofluorescence proves to be excellent with a sensibility between 95 and 97,5 p. 100 and a specificity between 97,5 and 99 p. 100.

[Contribution of immunoglobulin assays to the diagnosis of human African trypanosomiasis in patients immunologically suspect (immunofluorescence and ELISA). A preliminary report (author's transl)]. / Apport du dosage des immunoglobulines pour de diagnostic de la trypanosomiase humaine africaine chez les suspects immunologiques (immunofluorescence et ELISA). Résultats préliminaires.

Can the diagnosis of sleeping sickness in patients immunologically suspect, without seeing the parasite, be obtained by dosing IgG and IgM? The authors demonstrate that two groups of people with positive immunodiagnosis, one parasitologically confirmed and the other not confirmed, do not show significant difference when dosing immunoglobulins. These two groups respectively show a significant difference when compared with a parasitologically and immunologicaly negative group. The simultaneous increase in IgG and IgM might confirm the immunodiagnosis.

[Test tube technique for field diagnosis of hemoglobin S (author's transl)]. / Utilisation sur le terrain du test en tube pour la détection des hémoglobines S.

Laboratory diagnosis of sickle-cell anemia requires expensive equipment often too sophisticated for rural dispensaries. Therefore haemoglobin precipitation in solutions of neutral salts appears to be a specific and reliable test, as valid as Emmel test, and easily performed during mass campaigns or within the technical and financial limitation of rural medicine.