Monitoring Dry Season Persistence of Anopheles gambiae s.l. Populations in a Contained Semi-Field System in Southwestern Burkina Faso, West Africa.

To gain insight into the dry season survival strategies of Anopheles gambiae s.l., a new contained semi-field system was developed and used for the first time in Burkina Faso, West Africa. The system consisted of a screened greenhouse within which the local environment was reproduced, including all ecological requirements for mosquito development cycle completion. The system was seeded with the progenies of female Anopheles gambiae, Anopheles coluzzii, and Anopheles arabiensis collected in the vicinity of the greenhouse during the rainy season. After successful establishment in the semi-field system, mosquito populations were monitored over a 1-yr period by regular surveys of larval and adult specimens. We provided evidence for the persistence of adult mosquitoes throughout the dry season, in the absence of any suitable larval development site. During the hot and dry periods, adult insects were observed in artificial shelters (clay pots, building blocks, and dark corners). The mosquito population rapidly built up with the return of the rainy season in the area, when artificial breeding sites were refilled in the enclosure. However, only An. coluzzii and, later, An. arabiensis were detected in the subsequent rainy season, whereas no An. gambiae specimen was found. Our findings suggest that An. coluzzii and An. arabiensis may be able to aestivate throughout the dry season in Southwestern Burkina Faso, whereas An. gambiae might adopt a different dry-season survival strategy, such as long-distance re-colonization from distant locations. These results may have important implications for malaria control through targeted vector control interventions.

Transient locked-in syndrome and basilar artery vasospasm.

BACKGROUND: Cerebral vasospasm is the main cause of neurological mortality and morbidity following subarachnoid hemorrhage. Basilar artery vasospasm (BAVS) is associated with a high morbidity and may have multiple clinical presentations. METHODS: We report the case of a 43 years-old man with BAVS presenting as a reversible locked-in syndrome (LIS) after stopping sedation. RESULTS: The symptoms were successfully managed by intra-arterial infusion of vasodilators and balloon angioplasty. Magnetic resonance imaging did not reveal any brainstem lesion 48 h after the complication, demonstrating a hemodynamic mechanism. CONCLUSION: LIS can reveal BAVS. Its diagnosis relies on clinical examination. In this case, rapid neuro-interventional treatment permitted reversal of symptoms. This could not have been possible under sedation.

[Assessment of efficacy of hypertonic saline - hydroxyethylstarch in haemorrhagic shock]. / Intérêt du mélange sérum salé hypertonique-hydroxyéthylamidon lors du choc hémorragique.

OBJECTIVE: Assessment of haemodynamic, respiratory and renal effects of hypertonic saline-hydroxyethyl starch (HyperHES) in critically ill-patients with hemorrhagic shock. PATIENTS AND METHODS: Seventeen mechanically ventilated patients with hemorragic shock benefiting from a cardiovascular monitoring by PiCCO device and requiring rapid volume loading. Two hundred and fifty milliliters of HyperHES were given over 5 minutes. The efficacy of volume loading was assessed by the measure of the systolic arterial pressure (SAP), cardiac index (CI), stroke volume variation (SVV) and the indexed systemic vascular resistance (iSVR). Studied parameters were assessed at baseline, 5, 30, 60 and 180 minutes after the end of HyperHES infusion. RESULTS: SAP (105 + or - 23 vs 77 + or - 10; p<0.001) and CI (4.8 + or - 1.1 vs 3.5 + or - 0.9; p<0.001) were significantly increased whereas iSVR (1175 + or - 310 vs 1501 + or - 337; p<0.01) and SVV (13 + or - 7 vs 20 + or - 5; p<0.01) were significantly decreased 5 minutes after the HyperHES infusion. Sodium (145 + or - 6 vs 136 + or - 5; p<0.001) and chloride (118 + or - 7 vs 107 + or - 6; p<0.001) were increased 5 minutes after the infusion. The PaO(2)/FiO(2) ratio as the extravascular lung water was not influenced by the infusion. The follow-up of renal parameters during the three first days (creatinemia, uremia and diuresis) did not revelead significant variations. CONCLUSION: In patients with hemorrhagic shock, the infusion of hypertonic saline (7.5%) hydroxyethyl starch association was followed by an increase in SAP, CI serum sodium and chloride concentrations. STUDY DESIGN: Prospective observational study.

Maternal social stress during late pregnancy affects hypothalamic-pituitary-adrenal function and brain neurotransmitter systems in pig offspring.

Maternal stress in pregnant sows may induce long-lasting alterations in the behavior, physiology, and immunity of their offspring. The aim of the present study was to investigate the consequences of repeated social stress during late gestation on determinants of the hypothalamic-pituitary-adrenal axis and on hippocampal neurotransmitter profiles in pig offspring. All pregnant gilts were housed in pairs. Each Stress gilt was mixed with an unfamiliar gilt twice a week between days 77 and 105 of gestation (n=18). Control gilts were housed in stable pairs over the same period (n=18). Plasma cortisol and corticosteroid binding globulin (CBG) were measured in 1 male and 1 female per litter in a basal situation on postnatal days (PND) 4, 26, and 60 and in a stressful situation at PND 28 (2 d after weaning) and 62 (2 d after relocation to a new building). Prenatal stress had no effect on plasma cortisol, but it decreased CBG at PND 26. Brain and adrenals were collected from 1 female per litter after weaning or relocation at PND 28 and PND 62. Adrenals were additionally collected at PND 4. Glucocorticoid receptor binding in the hippocampus and hypothalamus was not affected by prenatal treatment. However, prenatal stress increased the expression of 11beta-hydroxysteroid dehydrogenase type 1 mRNA in the hippocampus after weaning (P<0.05) and after relocation (P=0.08). In addition, prenatally stressed piglets showed an increased 5-hydroxyindole-3-acetic acid to 5-hydroxytryptamine ratio in the hippocampus after weaning and increased hippocampal c-fos mRNA expression and noradrenaline concentration after relocation (P<0.05). Prenatal stress also increased the relative adrenal weight at PND 4 and the cell density in the cortex and the medulla at PND 28, whereas no difference was found for activities of catecholamine-synthesising enzymes in the medulla. Overall, our data indicate that repeated social stress during pregnancy has long-lasting consequences on hypothalamic-pituitary-adrenal axis and hippocampal neurotransmitter activity in the offspring of pigs.

Behavioural, endocrine and immune responses to repeated social stress in pregnant gilts.

Pregnant sows are exposed to various stressors in intensive pig husbandry that may have negative consequences on their health, reproductive performances and welfare. Social stress is one of these challenges, because gestating sows have to be housed in groups according to EU guidelines (2001/88/CE). The purpose of this study was to determine the consequences of repeated social stress in pregnant female pigs on their behavioural, endocrine and immunological responses and on pregnancy outcome. Pregnant gilts were submitted to a repeated social stress procedure induced by housing unfamiliar gilts in pairs changed twice a week between days 77 and 105 of gestation (S group, n = 18). Control gilts were housed in stable pairs during the same period (C group, n = 18). Agonistic behaviour was observed during the first 3 h after each grouping. Skin lesions were numbered 2 h after each grouping. Salivary cortisol was measured before and repeatedly during the 4 weeks of grouping. Gilts were immunized against keyhole limpet haemocyanin (KLH) on days 81 and 95 of gestation. Immunoglobulins G against KLH, proliferative responses to concanavalin A, lipopolysaccharide, pokeweed mitogen and KLH and peripheral blood leukocyte numbers were evaluated 1 week before the first grouping and 3 days after the last one. Agonistic interactions and skin lesions were observed in S gilts at each grouping, although there was a decline between the first and the last grouping (P < 0.05). The repeated social stress induced a sustained endocrine response as shown by elevated salivary cortisol levels from 1 to 48 h after grouping in S gilts compared to C gilts. The cellular as well as the humoral immunity and the leukocyte numbers were not influenced by social stress. Gestation length tended to be shorter in S gilts (P = 0.09), but litter size, piglet weight or mortality at birth were not affected. Variability of the response of S gilts to groupings was partly explained by their average success value determined according to the outcome (defeat or win) of all the groupings. In conclusion, our study demonstrates that the application of repeated social stress to pregnant gilts during the last third of their gestation repeatedly activates their hypothalamo-pituitary-adrenal axis but does not impair their immune function and pregnancy outcome.

Prenatal stress, fetal imprinting and immunity.

A comprehensive number of epidemiological and animal studies suggests that prenatal and early life events are important determinants for disorders later in life. Among them, prenatal stress (i.e. stress experienced by the pregnant mother with impact on the fetal ontogeny) has programming effects on the hypothalamic-pituitary-adrenocortical axis, brain neurotransmitter systems and cognitive abilities of the offspring. This review focuses on the impact of maternal stress during gestation on the immune function in the offspring. It compares results from different animal species and highlights potential mechanisms for the immune effects of prenatal stress, including maternal glucocorticoids and placental functions. The existence of possible windows of increased vulnerability of the immune system to prenatal stress during gestation is discussed. Several gaps in the present knowledge are pointed out, especially concerning the time when prenatal stress effects are expressed during postnatal life, why this expression is delayed after birth and whether prenatal stress predisposes to immune-related pathologies later in life.

Outbreaks of serogroup X meningococcal meningitis in Niger 1995-2000.

In the African meningitis belt, the recurrent meningococcal meningitis epidemics are generally caused by serogroup A. In the past 20 years, other serogroups have been detected, such as X or W135, which have caused sporadic cases or clusters. We report here 134 meningitis cases caused by Neisseria meningitidis serogroup X that occurred in Niamey between 1995 and 2000. They represented 3.91% of the meningococcal isolates from all CSF samples, whereas 94.4% were of serogroup A. Meningococcal meningitis cases were detected using the framework of the routine surveillance system for reportable diseases organized by the Ministry of Public Health of Niger. The strains were isolated and determined by the reference laboratory for meningitis in Niamey (CERMES) and further typed at the WHO collaborating center of the Pharo in Marseille and at the National Reference Center for the Meningococci at the Institut Pasteur. Reference laboratories in Marseille and Paris characterized 47 isolates having the antigenic formula (serogroup:serotype:sero-subtype) X:NT:P1.5. Meningitis cases due to meningococcus serogroup X did not present any clinical or epidemiological differences to those due to serogroup A. The seasonal incidence was classical; 93.3% of the cases were recorded during the dry season. The mean age of patients was 9.2 years (+/- 6 years). The sex ratio M/F was 1.3. Case fatality rate was 11.9% without any difference related to age or sex. The increasing incidence of the serogroup X was not related to the decrease of serogroup A, but seemed cyclic, and evolved independently of the recurrence of both serogroups A and C.

Recent urban growth and urinary schistosomiasis in Niamey, Niger.

A cluster sample survey was conducted in 1998 in 30 schools to assess the effect of the growth of Niamey during the last decade on a urinary schistosomiasis urban focus described in 1989. Two thousand and forty-two children (11.0 + 0.1 years old) had a urine filtration test and answered a behavioural questionnaire. Snail populations of the sites used by schoolchildren were followed up in 1999. The global prevalence was 15.7% in 1998, as opposed to 23.7% in 1989. The prevalence was very low in schools far from the river and higher in those along the Niger banks, particularly in villages on the periphery of the urban area. Geographical factors were more important than socio-economic ones in explaining the distribution of the disease. Only 46% of the children in Niamey reported water contact; mainly in the river, rarely in pools and the canal. The infection risk was low in pools (RR = 1.6), high in the river (RR = 3.5) and very high in the canal (RR = 12.5). Malacological studies confirmed the location of transmission sites obtained through parasitological studies and the questionnaire. Sixty-one per cent of the children travelled outside Niamey to the hyperendemic surrounding areas. However, these movements did not increase their infection level. The results are discussed in relation to water contact behaviour and Schistosoma haematobium transmission features.

Vaccination of patas monkeys experimentally infected with Schistosoma haematobium using a recombinant glutathione S-transferase cloned from S. mansoni.

The capacity of a recombinant glutathione S-transferase from Schistosoma mansoni (rSm28GST) to vaccinate primates (Erythrocebus patas) against a heterologous infection with Schistosoma haematobium has been tested. Two injections of the purified molecule with Muramyl-Di-Peptide (MDP) as adjuvant resulted in a high level antibody response in the five immunized animals and in a significant reduction in worm fecundity compared to the controls which received adjuvant alone. Mean levels of daily egg excretion in urine an faeces were reduced by respectively 55% and 74% although perfusion revealed that worm burdens were similar in both groups. The protective effect was long lasting since it was maintained up to the end of the experiment, 42 weeks after infection. Hatching rates and the numbers of intra-uterine eggs were also significantly affected by the vaccination. Tissue eggs were also drastically diminished in the urogenital system (-80%) but the reduction was not statistically significant. One animal was not protected by the immunization. There was a good correlation between parasitological data and the intensity of bladder lesions assessed by microscopic examination. Polypoid formations together with an intense exudation of the lamina propria were frequently seen in the controls but rarely in the vaccinated group where formation of scar tissue was predominant. These results underline the vaccine potential of the recombinant Sm28GST as a possible valuable prophylactic tool for the control of egg-induced pathology and transmission of African schistosomes.

Vaccination of goats against the trematode Schistosoma bovis with a recombinant homologous schistosome-derived glutathione S-transferase.

We assayed the vaccine potentialities of a recombinant S. bovis-derived glutathione S-transferase (rSb28GST), member of a molecular family already shown to have protective capacities in the S. mansoni and S. japonicum models. Injection of the rSb28GST in Freund's Complete Adjuvant resulted in good specific IgG responses allowing all the animals to display high antibody titres on the day of experimental challenge with S. bovis cercariae. No statistically significant differences were observed in the faecal egg output. Although tissue egg counts in vaccinated animals were lower than in controls, the difference was not statistically significant, apart from the number of eggs trapped in the liver (P < 0.05). Likewise, PCV values remained parallel between the two groups. However, immunized goats gained 1.4 kg of body weight throughout the experiment whereas controls lost 1.2 kg (P < 0.05). In addition, the mean worm burden, assessed by perfusion 20 weeks after infection, was significantly reduced by 48% in the vaccinated group, the sex ratio being unaffected. It appears that a recombinant homologous protein can affect, in a natural host, the course of an experimental infection with a local strain of S. bovis, by affecting worm viability but not fecundity. These results also point to the striking differences in the effect of vaccination according to animal species. Because it has the capacity to prevent growth impairment due to schistosome pathogenicity, the molecule can be proposed as a valuable tool in the development of vaccine-based control programs in endemic areas.

[The use of screens in the anti-tsetse campaign in the forest zone]. / L'utilisation des ecrans dans la lutte anti-tsetse en zone forestière.

After preliminary studies on the ecodistribution of Glossina palpalis s.l. in the sleeping sickness focus of Vavoua (Ivory Coast) trials with screens impregnated with decamethrine were carried out. Artificial supports for insecticide present several advantages: less pollution, less costly, simplicity, facility of use by local personnel, possibility of re-use, integration with other methods. On the other hand, its action based on the attraction of flies which come into contact with the screen is relatively slow, particularly in obtaining a complete interruption of reproduction. The technique is compared with other control methods as the use of biconical traps and selective spraying along borders. Its action can be improved by the addition of attractive host odours or sex pheromones.