Hernia discal lumbar en el adolescente. Tratamiento conservador con corsé dorsolumbar / Lumbar disc hernia in the adolescent: conservative treatment with a dorsal-lumbar corset

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Therapeutic efficacy of sulphadoxine/pyrimethamine and susceptibility in vitro of P. falciparum isolates to sulphadoxine-pyremethamine and other antimalarial drugs in Malawian children.

Since 1993 sulphadoxine/pyrimethamine (SP) has been used as the first-line drug for uncomplicated Plasmodium falciparum malaria in Malawi. To investigate the current efficacy of SP and other antimalarial drug resistance, we studied in vivo and in vitro responses to SP, chloroquine (CQ), mefloquine (MF), quinine (QN), and halofantrine (HF) in Salima, central Malawi. In a follow-up of 14 days, nine (13.8%) of 65 children under five showed RII/RIII parasitological resistance, and in in vitro microtests 18 (62.1%) of 29 isolates showed < 90% inhibition of schizont maturation at pyrimethamine 75 nmol/l blood medium mixture, indicating resistance. The discrepancy between in vivo and in vitro results might be partially explained by acquired immunity in this holoendemic area. In vitro one (3.4%) of 29 isolates failed schizont inhibition at 1.6 micromol/l blood of CQ, indicating resistance. Compared with an in vitro study conducted in 1988 in another region of Malawi using the same cut-off point, the proportion of resistant isolates had decreased significantly (P < 0.01). Although 31% of isolates were borderline, showing schizont maturation at 0.8 micromol/l blood but no schizonts at 1.6 micromol/l in our study, the results suggest possible recovery of CQ sensitivity after long-term absence of drug pressure. Resistance remains a major problem in malaria control. Monitoring resistance patterns in vitro provides early warning signs of impending loss of therapeutic efficacy of the standard treatment, and may detect changing patterns in alternative drug resistance.

Profile of Morong, Bataan, an area of low malaria endemicity in the Philippines.

A malaria study area in the Philippines is described. It consists of the municipality of Morong, Bataan on the Island of Luzon. In January 1992, the population was 19454 in 106 villages located on a narrow coastal plain, or in valleys of streams running from the mountainous interior. This is an area of low level but persistent seasonal transmission of malaria with approximately one thousand cases reported each year, mainly from February to July. In spite of the low level of malaria, it is apparently quite stable. The study site has been used to investigate parameters leading to stable malaria. Hypotheses tested were that there was substantial under reporting of cases; that there was strain specific immunity stabilising the incidence of malaria and that malaria transmission in this area is highly localised in small regions with a high enough malaria prevalence to account for the year to year stability. The study plan included cross sectional surveys of parasite prevalence and seropositivity, longitudinal surveys, passive case detection, entomological surveys, anthropological surveys to assess knowledge of malaria and documentation of the health-seeking behaviour of the population.

Field epidemiological studies on malaria in a low endemic area in the Philippines.

Field epidemiological studies were conducted to examine factors affecting endemicity in an area with a low prevalence of malaria. Two annual cross sectional surveys were done to estimate parasite prevalence rates at two periods in time, to determine the distribution of the parasitemic population and to describe the serological status of the population. A longitudinal study of a sample of infected people was used to measure reinfection rates and antibody dynamics. A 2 year passive case detection was done to estimate the number and distribution of people with symptomatic infections. Malaria was found in all age groups, with marked clustering of cases. Active and passive case detection and serological surveys all gave a similar pattern of malaria distribution: generally low prevalence with small foci of relatively high endemicity. The infection frequencies were generally similar in all age groups, measured by both active and passive case detection. There was a high frequency of P. falciparum gametocytemic infections in the asymptomatic cases found through active case detection. Twenty to 39 year old males had the highest frequency of infection by active case detection, and 10-19 year old males by passive case detection. These two groups were also more likely to be gametocyte positive than their female counterparts, suggesting that in this community, this portion of the population acts as the main reservoir of infection.

Risk factors for infection with malaria in a low endemic community in Bataan, the Philippines.

The patterns of malaria morbidity and mortality can vary with the level of malaria transmission in a given area. We carried out two annual cross-sectional surveys in the hypoendemic malarious community of Morong, the Philippines, to examine epidemiologic and sociobehavioural risk factors for infection. In both surveys, the greatest risk of having malaria was associated with place of residence. For example, in the first survey, living in an area where more than 50% of the community had a high IFAT titer had an adjusted odds ratio (OR) of 33.7. A range of activities thought to be associated with risk were examined, but in the first survey, only frequent nocturnal visits to the forest were found to be a significant risk factor overall (adjusted OR; 2.65; 95% CI 1.48, 4.73), but this phenomenon was primarily observed among individuals residing in the lowest prevalence areas. In the second survey, where only the area with a relatively high prevalence of malaria was sampled, no association with activities was found. In this survey, significant factors associated with malarial infection were: being a migrant (adjusted OR 1.97; 95% CI 1.33, 2.92), being male (adjusted OR 1.63; 95% CI 1.10, 2.43) and age 30 years or less (adjusted OR 0.29 for age > 30 years; 95% CI 0.16, 0.52). The data suggest that in low-endemic communities like Morong, Bataan, control efforts should be primarily directed to focal areas identified by serology, particularly among migrants and among male young adults.

Stability of malaria in a community in Bataan, the Philippines: prospects for control.

Malaria in Morong, Bataan, The Philippines, a municipality with relatively low level, but stable malaria is associated with small foci of relatively high endemicity. Although there is little association between age and symptomatic malaria, there is a reservoir of asymptomatic cases which are present throughout the year. Risk analysis suggests that the greatest risk factor in acquiring malaria depends on place of residence and not on occupation, including those associated with forest activities such as charcoal making. Foci of infection and the timing of symptomatic cases is closely correlated with breeding sites and abundance of adult Anopheles flavirostris. In spite of this close association, widely held views in the community that malaria is not related to mosquito transmission are likely to make better malaria control based on vector control difficult to sustain. Observation of treatment practices in the community and estimates of the number of apparently asymptomatic carriers from active case detection illustrate the importance of delayed treatment in providing a continuing reservoir of infection. These results highlight the need for improved early case detection and treatment.

The pharmacokinetics and electrocardiographic effects of chloroquine in healthy subjects.

Chloroquine prophylaxis was administered to 3 healthy male volunteers at 100 mg base/day for 25 days, followed by the curative dose at 25 mg base/kg for 3 days. Subjects attained effective chloroquine (mean = 50 micrograms/l) and desethylchloroquine (mean = 17 micrograms/l) concentrations by the 3rd week of prophylaxis, underlining the need to start chloroquine prophylaxis two weeks before travel. On the second day of the treatment period, hourly electrocardiographic monitoring showed a diminution of the T wave and prolongation of the QTc interval, manifesting cumulatively during the 3 days' curative dose, but with no cardiac symptoms. A dose-dependent cumulative effect of chloroquine was demonstrated with higher blood concentrations during the treatment period. Electrocardiographic readings spontaneously normalized after the treatment period as drug concentrations diminished progressively.

In-vitro tests on Philippine isolates of Plasmodium falciparum against four standard antimalarials and four qinghaosu derivatives.

In-vitro drug sensitivity tests were performed on Philippine isolates of Plasmodium falciparum between 1991 and 1993, using the radioisotope microdilution method. The success of the tests varied significantly with the level of parasitaemia, the source of the strains, the period that elapsed before culturing, and the detectable concentrations of antimalarials in the blood. There was a significant positive correlation between the IC50 values for chloroquine and artesunate and the level of chloroquine in the blood before testing. In the Philippines the sensitivity profiles of the standard antimalarials (chloroquine, quinine, mefloquine, and halofantrine) were less severe than those in other south-east Asian countries. Fairly low IC50 values were obtained for the qinghaosu derivatives artemisinin, artemether, arteether and artesunate. There was a positive correlation between quinine, mefloquine, halofantrine and some of the qinghaosu derivatives, and between the qinghaosu compounds themselves, raising the possibility of either cross-resistance or possible drug associations.

Mefloquine-halofantrine cross-resistance in Plasmodium falciparum induced by intermittent mefloquine pressure.

The study was designed to evaluate how exposure of Plasmodium falciparum to mefloquine modifies the sensitivity of the parasite to four major antimalarial drugs. A recently culture-adapted strain of P. falciparum was subjected to intermittent drug pressure at three different mefloquine concentrations (2.34, 4.68, and 9.37 ng/ml). Growth was monitored by daily evaluation of parasitemia on thin smears. Drug sensitivity tests were done weekly, using a radioisotope microdilution method. Mefloquine was removed from culture media when decreasing parasitemia was observed, and reintroduced when multiplication reoccurred. Parasite survival was inversely proportional to drug concentrations. The parasites tolerated progressively higher concentrations of mefloquine with prolonged exposure to the drug. Throughout this adaptation, the 50% inhibitory concentration for chloroquine and quinine showed no modification, but it increased considerably for mefloquine, exceeding known levels of resistance. Furthermore, a parallel increased resistance to halofantrine was observed, surpassing the normal range of sensitivity. Cross-resistance between mefloquine and halofantrine shown in this study has now been confirmed by epidemiologic in vitro surveys and clone analysis. These findings may have important in vivo consequences and eventually affect the choice of antimalarial therapy.

[Cross resistance to mefloquine and halofantrine in a case of P. falciparum malaria contracted in Sierra Leone]. / Résistance croisée à la méfloquine et à l'halofantrine lors d'un paludisme à P. falciparum contracté en Sierra Leone.

Malaria caused by P. falciparum occurred during prophylaxis with mefloquine upon return from Sierra Leone (zone II). A typical and not recognized, with negative results of initial hematological examinations. Diagnosed on D.26 with parasitemia of 0.2%. Successful treatment of clinical symptoms with halofantrine but increased anemia and positive parasitemia at D.7. Successful treatment with chloroquine. Chemosensitivity tests confirmed sensitivity to chloroquine, threshold sensitivity to quinine (IC50 = 297), resistance to mefloquine (IC50 = 76) despite high levels in bloods, and to halofantrine (IC50 = 7-laboratory normal value = 1). This cross-resistance of P. falciparum originating from Sierra Leone to mefloquine-halofantrine seems to be the first observation of this danger in Africa. Prescription of chloroquine is still imperative in zone 11 countries.