Plasma levels of tumor necrosis factor during a longitudinal survey in an endemic area of malaria

The plasma levels of tumor necrosis factor were measured during a longitudinal survey of 84 subjects living in an endemic area of malaria. In most cases, the plasma tumor necrosis factor was found at its highest level during the malaria transmission peak and became normal again during the dry season. Children having suffered from malarial attack keep low tumor necrosis factor levels compared to adults and asymptomatic children. These results suggest that tumor necrosis factor could be associated with the development of resistance against malaria.

Plasmodium falciparum growth inhibition by human platelets in vitro

Platelets take an active part in immunological processes as well as in haemostasis, especially in the host-parasite relationship. Our aim is to assess the growth of Plasmodium falciparum, cultured in human erythrocytes in the presence of fresh washed human platelets, since thrombocytopaenia is frequently observed during malarial infections. Our results show that platelets induce a dose-related growth inhibition of P. falciparum. Both proliferation and maturation of intraerythrocytic stages of the parasite are inhibited. This growth inhibition is triggered by the parasite itself as neither specific antibodies nor any other components are needed to activate platelets. Activated platelets are directly toxic since complement is not involved. Furthermore, inhibition is not mediated by erythrocyte lysis or by toxic oxygen metabolites. Platelets induce an inhibition of P. falciparum growth, at least in vitro, although the importance of their role played in vivo in malarial immunity has yet to be evaluated.

Serological reactivity to the ring-infected erythrocyte surface antigen and circumsporozoite protein in gravid and nulligravid women infected with Plasmodium falciparum

To investigate potential mechanisms for pregnancy-associated alterations in the immune response to malaria, we tested plasma samples from Plasmodium falciparum-infected nulligravida (42), primigravida (23) and multigravida (38) Kenyan women for reactivity to the ring-infected erythrocyte surface antigen (RESA) by a modified indirect fluorescent antibody assay and to synthetic peptides derived from amino acid sequences of RESA and the circumsporozoite (CS) protein of P. falciparum by an enzyme-linked immunosorbent assay. Reactivity to RESA showed the lowest titres in primigravid women, intermediate titres in nulligravid women and the highest titres in multigravid women (loge mean antibody = 3.28, 4.64, and 5.28, respectively, P less than 0.03), but was not associated with initial parasite density or response to chloroquine treatment. No relationship in antibody reactivity to the 3 synthetic peptides of the RESA molecule was observed by gravidity (0, 1, or greater than or equal to 2), age, initial parasite density or response to treatment. Levels of antibody to the synthetic peptides of the CS protein increased with age and were higher in gravid than in nulligravid women in the 15-19 year age group. The increased malaria prevalence and parasite density and the decreased response to antimalarial treatment in pregnant women is not explained by lower levels of antibody to RESA or CS protein during pregnancy.

Therapeutic results in opisthorchiasis with praziquantel in a reinfection-free environment in France

108 patients coming to France from Southeast Asia were treated with praziquantel (2-cyclohexylcarbonyl-1,2,3,6,7,11b-hexahydro-4H-pyrazino[2,1-a] isoquinolin-4-one, EMBAY 8440, Biltricide) for opisthorchiasis. All patients, 31 children and 77 adults, were examined at the Department of Parasitic Diseases 30 to 90 days after arrival in France. They came from Laos (79 cases), Viet Nam (4 cases) and Cambodia (25 cases), generally via Thailand. 6 heavy (10 000-19 999 eggs per gram of faeces, EPG), 23 moderate (1000-9999 EPG) and 79 light infections (1-999 EPG) were detected. Praziquantel was given at a dose of 25 mg/kg body weight, three times on a single day at intervals of 4 h. The biological tolerability was excellent without any variation of the biological norm values (47 parameters). Clinical tolerability was perfect in 48 patients and pretty good in the 60 remaining cases. We only observed, for one or two days, lassitude, headache, drowsiness, nausea, epigastric pain or arthralgia-myalgia always of weak or moderate intensity. The therapeutic efficacy is remarkable with 100% cure in all patients who were followed-up for 90 days. All earlier controls (7th, 20th, 40th days) were always negative except for one child with a light infection still weakly positive at the 7th, 20th and 40th day controls but negative, too, after 90 days.