[Genomic, molecular biology and malaria: new medical perspectives?]. / Génomique, biologie moléculaire et paludisme: quelles avancées médicales?

The knowledge of genomic structure of man, of Plasmodium falciparum and of its main vector Anopheles gambiae has led to great progress in the understanding of malaria pathophysiology. It may also offer new perspectives for malaria therapy vaccines or control of mosquito-borne transmission. In pathophysiology, genes encoding adhesion plasmodial proteins of their receptors were identified, as well as other genes controlling the patient immune response or the antigenic parasite variability. From a therapeutic point of view, new targets for future antimalarial drugs were identified, mainly in apicoplast (a vestige of vegetal structure incorporated by the parasite during its phylogenic evolution) and several enzymes, particularly proteases. It will be now necessary among these "promising new molecules" to select a few ones (probably no more than 5 or 6) for a pre clinical and clinical pharmaceutical development. Indeed, the industrial possibilities for developing new antimalarial drugs are evidently limited and several other antimalarial drugs are already under development. For future malaria vaccines, several new targets and antigenic proteins were also identified. As for new drugs, a complete evaluation of these antigens is absolutely necessary to select few of them for clinical development. Particularly for malaria, ADN vaccines may offer very promising perspectives with the possibility to obtain both humoral and cellular immunity and to use at the same time a panel of plasmodial antigens. It could be thus possible to obtain a simultaneous immunization against different stages of Plasmodium falciparum (sporozoites, merozoites, gametocytes) and to use, as an adjuvant, a gene encoding a viral protein or a cytokine (GMCSF). In Anopheles gambiae genome, several genes encoding for key-proteins, particularly odorant receptors necessary for blood meals, were identified. Non biting-non transmitting mosquitoes were obtained by genetic manipulation and, from an academic viewpoint, offer a very attractive new perspective for the interruption of malaria transmission. Unfortunately several practical problems remain unsolved and genetically modified mosquitoes do not survive long enough among "wild" strains. On the whole genomic and proteomic gave very exciting scientific results in malaria and, very probably the post-genomic phase will even give more new data. From a practical, medical viewpoint, it is still too early and speculative to imagine their possible applications for malaria control.

In vitro susceptibility of Aspergillus spp. clinical isolates to albendazole.

The in vitro antifungal activity of albendazole, a benzimidazole widely used as an antihelmintic drug in humans, was investigated and assessed for its activity against Aspergillus spp. Forty-eight isolates, representing the most frequent species found in human pathology [Aspergillus fumigatus (n = 27), Aspergillus flavus (n = 10), Aspergillus terreus (n = 7), Aspergillus nidulans (n = 3) and Aspergillus niger (n = 1)], and one quality control strain (A. niger ATCC 9804 83435) were tested according to the NCCLS M38-P methodology for moulds. All the strains were susceptible to albendazole, with homogeneous MICs for each species; three strains were resistant to itraconazole.

Usefulness of Western blot in serological follow-up of newborns suspected of congenital toxoplasmosis.

The goal of the study reported here was to compare the results of Western blot with other serological methods for testing newborns suspected of having congenital toxoplasmosis. Western blot, enzyme-linked immunosorbent assay, immunoglobulin (Ig)M immunosorbent agglutination assay, and indirect immunofluorescence assay were performed on the sera of 126 neonates collected at birth and at 1 and 3 months of life. Western blot was more sensitive than IgM detection with the immunosorbent agglutination assay (82.6% vs. 69.6%), and the specificity of the two methods was 96.1% and 92.2%, respectively. Among the serological techniques tested, the combination of Western blot (IgG and IgM) with IgM immunosorbent agglutination assay achieved the greatest improvement in the sensitivity of early (postpartum) diagnosis of congenital toxoplasmosis.

[Emerging parasitosis ans mycosis: risk and threats for the new millenium]. / Emergence de parasitoses et mycoses: risques et menaces au seuil de troisième millénaire.

For multiple reasons, the emergent infectious risks do not stop increasing these last twenty years. The climatic modifications and the human interventions modifying the biotope as well as the rapid spreading of resistant strains to treatments, generate re-emergence or emergence, all the more dramatic as the means of fight are reduced. These emergent or re-emergent diseases are extremely worrisome as their diagnosis and their prevention are often difficult. The important infesting power of parasites and the particularly effective capacities of adaptation of these eucaryotes contributed to the public health problems. Anthropozoonoses and zoonoses constitute a permanent risk the control of which is imaginary. The new pathogenic agents, the unusual clinical demonstrations in the context of deficiency of the host immune functions imply attentiveness and a permanent up to date of the knowledge of the biologist and of the different professionals of health. The risks with which are confronted the humanity during this century underline the necessity of determining mechanisms involved in the pathogenesis. The determination of the specific and vital biologic processes for the microorganism, could allow to define the most appropriated targets and the most effective and original means of fight.

[Congenital toxoplasmosis: prevention in the pregnant woman and management of the neonate]. / Toxoplasmose congénitale: prévention chez la femme enceinte et prise en charge du nouveau-né.

The management of a pregnant women or a child infected by Toxoplasma gondii rests on the screening of pregnant women at risk of infection. Treatment is prescribed if an infection occurs. A prenatal diagnosis (detection of T. gondii in amniotic fluid) may be performed, a positive result leading to a reinforcement of the treatment. After birth, the follow-up of the child is needed in order to prevent and detect the sequellae, mainly ocular. For all these steps, the biological methods used to diagnose T. gondii infection are of paramount importance.

Eight-year surveillance of environmental fungal contamination in hospital operating rooms and haematological units.

An eight-year fungal environmental surveillance was carried out in 15 operating theatres and two haematological units. Sampling was performed twice a year in each room, using contact plates for plane surfaces and sterile swabs for grids. From 1992 to 1999, individual rooms in the 17 units were sampled on 1094 occasions and 3822 samples were collected. The percentage of rooms without fungus increased regularly between 1992 and 1999 (41.1% and 74.8%, respectively). The units were classified according to the fungal contamination during the eight years: the operating theatres which required the highest protection (cardiological, thoracic, vascular, hand, orthopaedic and neurosurgery) and the adult haematological unit showed least contamination (71.8% rooms were negative). The most frequent species isolated were Penicillium spp. (28.4%), Cladosporium spp. (15.6%) and Aspergillus spp. (7.6%). Aspergillus fumigatus was rarely isolated (3.7%), and was mainly isolated at the beginning of the study. This study demonstrates that environmental control programmes are effective in reducing environmental mould contamination and could be useful in establishing exposure guidelines, especially by defining an acceptable level of biocontamination in zones at risk.

[Role of local immunity in invasive pulmonary aspergillosis]. / Le rôle de l'immunité locale dans l'aspergillose pulmonaire invasive.

A LEADING CAUSE OF MORTALITY: Inhalation of fungal spores may cause infection and/or inflammation, which is dependent on the nature of the fungus as well as the individual's immune status. Aspergillus fumigatus is responsible for a dramatic pathology, invasive aspergillosis (IA). IA has become a leading cause of death, mainly among bone marrow transplantation or solid-organ recipients, but also among AIDS patients. IMMUNE RESPONSE: The diversity of immune failure suggests that many lines of immunity are implicated in the A. fumigatus elimination process. Non specific immunity plays a major role in the defence against A. fumigatus, including three major lines: anatomical barriers, humoral components, phagocytic cells. But acquired immunity plays a role with different T-cell subsets and their associated cytokines. FUNGUS-HOST RELATIONSHIPS: The relationship between the fungus and its host is complex and could be again study to improve the prevention and the treatment of IA. The aim of this review is a synthesis of the knowledge about the immunity response against Aspergillus fumigatus in IA.

[Prevention of congenital toxoplasmosis in France. Risk assessment. Results and perspectives of prenatal screening and newborn follow up]. / La prévention de la toxoplasmose congénitale en France. Evaluation des risques. Résultats et perspectives du dépistage anténatal et du suivi du nouveau-né.

In France, a national program for the prevention of congenital toxoplasmosis has been set up 25 years ago. This program is here presented and discussed in details. It is based on a decision tree well defined, with pre and/or per gravidic serological screening with several different tests, completed, if necessary, by ultrasounds examinations of the fetus, biomolecular tests (PCR) on amniotic fluid, and by clinical, biological, and radiological surveillance of neo-nates. The purpose of this prevention program is to: 1/identify nonimmune young women and limit their contamination risk during pregnancy by appropriate counseling on hygiene and diet; 2/screen and treat per gravidic toxoplasmosis as early as possible so as to prevent or limit transmission to the fetus and its consequences. 3/in utero diagnose and treat infestation of the fetus; 4/diagnose and treat asymptomatic congenital toxoplasmosis in neonates, to prevent risks of reactivation and late complications, especially ocular. Such a prevention program has a cost validated by the prevalence of acquired toxoplasmosis in adults in France (over 50% of the population) and by the yearly incidence of congenital toxoplasmosis (at least 0.1% of births according to the best hypothesis). These 6 to 700 congenital toxoplasmosis cases per year may be compared to the 6 to 7,000 per gravidic seroconversions which could lead to fetal contamination if no preventive measures are taken. Nevertheless, as it is often the case in the field of prevention, it is very difficult to statistically assess the efficacy of this program even though several arguments show that it allows to eliminate the most serious toxoplasmosis, sources of serious handicaps at birth, and to limit the frequency of late complications (especially retino-choroiditis) of asymptomatic infections in neonates. The position of European countries varies as to prevention of congenital toxoplasmosis. Some countries (Austria, Belgium) have national prevention programs similar to the French one, whereas others have set up only limited programs or set up no systematic prevention. These differences may be accounted for by the different frequencies of toxoplasmic risk. It seems mandatory to forget all dogmatism and not to stick to a strictly statistical approach for a disease with not only medical but also social and human consequences.

Parasitic diseases and immunodeficiencies.

In the last two decades, major immunodeficiency syndromes have strongly influenced medical parasitology. Some animal parasitoses, once unknown in human medicine, have become zoonotic and sometimes anthroponotic. In other cases, the clinical evolution of human parasitoses has been severely aggravated and/or modified in immunodeficient patients especially in toxoplasmosis, cryptosporidiosis, leishmaniasis, strongyloidiasis and scabies. The parasites implicated are varied (protozoa, helminths and even Acaridae) but have in common the capacity to reproduce in or on the human host. These immunodeficiency syndromes are often related to AIDS but other major immunodepressions, such as post-therapeutically in organ transplantation, may also be responsible and raise difficult problems for prevention. The munological mechanisms involved are not always well understood. In addition, genetic predisposition factors, gradually becoming better-understood in parasites and man, complete and complicate our understanding of the immunological mechanisms.

Tumour necrosis factor alpha receptors: role in the physiopathology of protozoan parasite infections.

Tumour necrosis factor alpha (TNF alpha) is an important cytokine in immune regulation and resistance to various micro-organisms. It provides signals to the target cells through two different receptors: TNFR1 and TNFR2. The present report reviews the role of TNF receptors (TNFRs) in the immune response against protozoan parasite infections of medical interest (Toxoplasma gondii, Leishmania major, Trypanosoma cruzi, Plasmodium spp.). TNF alpha has been regarded as a modulator cytokine in host defence against protozoans infections and recent findings on experimental gene-deficient mice have showed that TNF alpha/TNFRs pathway may be beneficial for host protection during these infections.

Chemokines in host-protozoan-parasite interactions.

Here, we review the interactions between parasites and chemokines and chemokine receptors in toxoplasmosis, trypanosomiasis, leishmaniasis, malaria and other diseases caused by protozoan parasites. The potential roles of chemokines after infection by these intracellular pathogens include host defence functions such as leukocyte recruitment, participation in cell-mediated immunity and antiprotozoal activity. However, these interactions can also help the parasite in, for example, the penetration of host cells.