Epidemic visceral leishmaniasis in southern Sudan.
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Adolescent↗
Biomedical subjects
A Moren
Publications and source records attributed to A Moren.
Adjustable portal film cassette holder for radiation therapy.
An adjustable portal film cassette holder has been designed and constructed. The holder provides for: holding portal film perpendicular to and centered with the central axis of the beam film-to-patient distance to minimize magnification; angling (swivel) film to match collimator angle; and ease of correct repositioning of arrangement when frequent filming is required. This device has now been in use for several months with good results.
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Visceral leishmaniasis in southern Sudan.
Reports made by Médecins Sans Frontières in Khartoum on an outbreak of visceral leishmaniasis among displaced people from the western Upper Nile prompted an investigation at Ler Hospital, the second largest in the region. In a 10 d period during April 1989, 100 persons with visceral leishmaniasis were identified. Of these, 82% were men; 67% were aged 20 to 39 years. Except for the absence of ulcerated skin lesions, the clinical features corresponded to those traditionally described in the Sudan. A cross-sectional serological survey was conducted in Kuernyang (400 inhabitants), 40 km north of Ler. The anti-Leishmania antibody prevalence was 18.2%, being higher among those older than 15 years, and higher among adult women (28%) than among men (18%). The overall prevalence of splenomegaly was 16.4%. 33% of seropositive cases presented with splenomegaly, compared with 11.6% of those who were seronegative. Three serological surveys conducted on the eastern side of the Nile showed no seropositive cases. However, 2 autochthonous cases were clinically diagnosed and confirmed by serological assays. The war conflicts and population movements appear to be the main cause of this large outbreak that may have killed thousands of tribespeople in southern Sudan. There is a risk of the disease spreading into other areas with devastating consequences for the population, should energetic measures not be immediately taken.
Adolescent↗
Permethrin-impregnated bed nets for the prevention of malaria in schoolchildren on the Thai-Burmese border.
A double-blind controlled trial was undertaken from August 1990 to February 1991 among Karen children on the Thai-Burmese border to evaluate the effects on malaria incidence and prevalence of permethrin-treated bed nets. Three hundred and fifty schoolchildren, aged 4 to 15 years, were allocated at random to receive either a permethrin-impregnated net or a non-treated net. The incidence of malaria infections, confirmed by a blood film, was assessed during 6 months. Three surveys were conducted, on admission and 3 and 6 months later, to measure the prevalence of infections and spleen rates. Compliance was assessed by monthly home visiting. The use of permethrin-treated bed nets reduced the number of parasitaemic Plasmodium falciparum infections by 38% and the number of symptomatic episodes by 42%. The number of P. vivax malaria attacks was similar in each group. The prevalence of positive blood films in the 2 groups did not change significantly during the study. A reduction in spleen rate by 50% in both groups at the end of the study period could not be related to the overall use of nets. Compliance was high and no side-effect was reported. The long-term effects on morbidity and mortality need to be assessed after distribution of permethrin treated bed nets at the village level.
Adolescent↗
Meningitis outbreaks and vaccination strategy.
Three outbreaks of meningitis caused by Neisseria meningitidis serogroup A (subgroup III) are described: Niger (1991), Burundi (1992), and Guinea (1993). These outbreaks showed unusual characteristics: a shorter inter-epidemic interval (Niger), unusual geographical location outside the meningitis belt (Burundi and Guinea), and high age-specific attack rates in all age groups (Burundi and Guinea). Mass immunization campaigns mobilized considerable human and financial means (US $322,000 and 3000 person-days of work for health personnel to immunize 629,000 people in Guinea). The vaccination coverage was over 80% in densely populated areas (Burundi and urban Guinea), but below 50% in less populated areas (24/27 and 26/30 sub-districts in Niger and Guinea, respectively). The preventive fraction (proportion of cases prevented by vaccination) was substantial in Guinea (35% for a vaccine efficacy of 85%) and was higher where the campaign was initiated earlier. An 'alert' threshold indicating the onset of an epidemic of 15/100,000 cases in one week showed good sensitivity (94%), specificity (98%) and positive predictive value (89%) in Burundi, permitting quick decision making outside the meningitis belt. These 3 meningococcal meningitis outbreaks show the need for epidemic emergency preparedness and for vigilance on the whole African continent.
Adolescent↗
[Vaccinal efficacy: measures and methodological constraints].
The safety and immunogenicity of vaccines are demonstrated before they are made available to doctors and the public. However, the protective activity against the disease for which a vaccine was designed can only be accurately measured in field trials. This involves its large-scale use in the target population. Epidemiology is the best approach to assess the results. This approach is based on the comparison of the incidence of the disease among vaccinated and non-vaccinated individuals. Three techniques can be used to estimate vaccine efficacy in a population: screening methods; cohort studies; and case control studies. These methods are most often used during epidemics, and this article discusses their application in this context. The validity of these methods depends on three criteria: that the administration of the vaccine to individuals in the population is random; that contacts between individuals in the population is random, and that vaccinated and non-vaccinated individuals have the same probability of encountering the infectious agent; that the population has equal susceptibility to the infection (other than the effect of the vaccine). If these conditions are not respected, the results of the analyses can be biased. The method involving calculation of the secondary attack rate in the families of index cases is the method where these conditions are most likely to be fulfilled.
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[Epidemiological and control aspects of meningococcal meningitis epidemics in Africa].
Meningococcal meningitis epidemics are a major health problem in sub-saharan Africa where they account for thousands of deaths and cause morbidity in hundreds of thousands of people. Meningitis is caused by Neisseria meningitidis. In Africa, epidemic meningitis is primarily due to strains of serogroup A which are responsible for the largest and most recent epidemics. N. meningitidis serotype 4, serosubtype P1.9, clonal complex III-1 was introduced into Africa in 1987. Since then, epidemics spread through the Lapeyssonnie's meningitis belt to the south. Classically, the 6 months-30 years old age group is the group at highest risk of disease. Nevertheless, in recent epidemics caused by clonal complex III-1, high age-specific attack rate occurred in those aged 30 years and over. The objectives of epidemic control are the reduction of mortality and morbidity. Early detection of an emerging epidemic is based on the observation of an incidence rate above a cutoff value. Recently, the WHO has proposed a cutoff of 15 cases/100,000/week averaged over two weeks. Epidemic investigation must be as rapid as possible after detection. The different steps are: confirmation of the epidemic and the meningococcal aetiology, standard case definition and determination of the high risk population. During epidemics, in developing countries, simplified treatment protocols are justified and a single dose of long-acting chloramphenicol is a useful first-line treatment. The strategy most frequently used for the control of epidemics is mass vaccination after the start of the epidemic. This must be done as quickly as possible.(ABSTRACT TRUNCATED AT 250 WORDS)
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[An outbreak of Heliotrope food poisoning, Tadjikistan, November 1992-March 1993].
The seeds and roots of Heliotropium lasocarpium, contain a pyrrolizidine alkaloid which causes toxic liver injury and veno-occlusive disease (VOD), characterised by an occlusive lesion of the centrolobular veins of the liver, when consumed by humans. The Farkhar region of Southern Tadjikistan, was blockaded from May to November 1992. This led to a famine and a delay of two months in the wheat harvest. Heliotropium lasocarpium had time to grow in the fields and their seeds were therefore collected with the wheat. The contaminated wheat was distributed to the population, who milled it and made bread. The first case of liver toxicity was six weeks after the first consumption of the contaminated bread. By March 1993, 3,906 cases had been recorded (attack rate = 4%). The attack rate were 0.4%, 5.4%, 4.0%, 2.8% and 1.5% for the less than 1 year, 1-14 years, 15-30 years, 31-50 years and over 50 years age groups respectively. The overall case fatality ratio (CFR) was 1.3% and increased with age from 0 to 5.9% in the same age groups. Two of the ten collective farms represented 83.3% of the cases attack rate of 16.9% and 23.6%. Four stages of illness were defined. Stage I corresponds to abdominal pain, nausea or vomiting, and asthenia. All stage I patients (55.5%) recovered rapidly. Stage II is an association of Stage I and hepatomegalia (29.9%). Stage III includes ascites in addition to these symptoms (13.7%) and stage IV alteration of consciousness (0.9%). The last case was reported on March 4th 1993.(ABSTRACT TRUNCATED AT 250 WORDS)
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