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B Ivanoff

Publications and source records attributed to B Ivanoff.

At least 37 records · Page 2Linked to original sources
PubMed1999

Considerations regarding mass vaccination against typhoid fever as an adjunct to sanitation and public health measures: potential use in an epidemic in Tajikistan.

We report on the ongoing epidemic of typhoid fever in Tajikistan that started in 1996. It has involved more than 24,000 cases to date, and is characterized by multiple point sources, overflow of sewage, contaminated municipal water, and person-to-person spread. Of the Salmonella typhi isolates available for testing in western laboratories, more than 90% are multidrug-resistant (MDR). Most recently, 28 (82%) of 34 isolates are resistant to ciprofloxacin, representing the first reported epidemic of quinolone-resistant typhoid fever. In the past, mass immunization during typhoid fever epidemics has been discouraged. A review of this policy is recommended in light of the alarming emergence of quinolone-resistant strains of S. typhi, the availability of improved vaccines, and the ongoing epidemic in Tajikistan. Mass immunization may be a useful measure for the control of prolonged MDR typhoid fever epidemics, as an adjunct to correction of municipal infrastructure and public health intervention.

Anti-Infective Agents↗
PubMed1999

Global burden of Shigella infections: implications for vaccine development and implementation of control strategies.

Few studies provide data on the global morbidity and mortality caused by infection with Shigella spp.; such estimates are needed, however, to plan strategies of prevention and treatment. Here we report the results of a review of the literature published between 1966 and 1997 on Shigella infection. The data obtained permit calculation of the number of cases of Shigella infection and the associated mortality occurring worldwide each year, by age, and (as a proxy for disease severity) by clinical category, i.e. mild cases remaining at home, moderate cases requiring outpatient care, and severe cases demanding hospitalization. A sensitivity analysis was performed to estimate the high and low range of morbid and fatal cases in each category. Finally, the frequency distribution of Shigella infection, by serogroup and serotype and by region of the world, was determined. The annual number of Shigella episodes throughout the world was estimated to be 164.7 million, of which 163.2 million were in developing countries (with 1.1 million deaths) and 1.5 million in industrialized countries. A total of 69% of all episodes and 61% of all deaths attributable to shigellosis involved children under 5 years of age. The median percentages of isolates of S. flexneri, S. sonnei, S. boydii, and S. dysenteriae were, respectively, 60%, 15%, 6%, and 6% (30% of S. dysenteriae cases were type 1) in developing countries; and 16%, 77%, 2%, and 1% in industrialized countries. In developing countries, the predominant serotype of S. flexneri is 2a, followed by 1b, 3a, 4a, and 6. In industrialized countries, most isolates are S. flexneri 2a or other unspecified type 2 strains. Shigellosis, which continues to have an important global impact, cannot be adequately controlled with the existing prevention and treatment measures. Innovative strategies, including development of vaccines against the most common serotypes, could provide substantial benefits.

Adolescent↗
PubMed1999

Mass vaccination with a two-dose oral cholera vaccine in a refugee camp.

In refugee settings, the use of cholera vaccines is controversial since a mass vaccination campaign might disrupt other priority interventions. We therefore conducted a study to assess the feasibility of such a campaign using a two-dose oral cholera vaccine in a refugee camp. The campaign, using killed whole-cell/recombinant B-subunit cholera vaccine, was carried out in October 1997 among 44,000 south Sudanese refugees in Uganda. Outcome variables included the number of doses administered, the drop-out rate between the two rounds, the proportion of vaccine wasted, the speed of administration, the cost of the campaign, and the vaccine coverage. Overall, 63,220 doses of vaccine were administered. At best, 200 vaccine doses were administered per vaccination site and per hour. The direct cost of the campaign amounted to US$ 14,655, not including the vaccine itself. Vaccine coverage, based on vaccination cards, was 83.0% and 75.9% for the first and second rounds, respectively. Mass vaccination of a large refugee population with an oral cholera vaccine therefore proved to be feasible. A pre-emptive vaccination strategy could be considered in stable refugee settings and in urban slums in high-risk areas. However, the potential cost of the vaccine and the absence of quickly accessible stockpiles are major drawbacks for its large-scale use.

Administration, Oral↗
PubMed1998

[Traveller's diarrhea: which vaccines?].

Diarrheal diseases are a major cause of child morbidity and mortality, particularly in developing countries. It is estimated that diarrheal diseases and typhoid fever cause around 2.5 million deaths per year in the world. Four bacteria and one virus share this responsibility: Shigella spp, Escherichia coli ETEC, Vibrio cholerae, Salmonella typhi and rotavirus. People travelling in countries with high endemicity of diarrhoeal diseases risk facing these four bacteria or the less common rotavirus, which is usually active in infants, even though some cases of diarrhoea due to rotavirus have already been reported in adults. The usual recommendations concerning basic measures of hygiene are most of the time quickly forgotten and followed only by a small number of travellers (12). Therefore, apart these useful recommendations, it is therefore necessary to consider complementary actions for controlling these diseases which are mainly transmitted by contaminated water and food. This article aims at giving an overview of currently available and future vaccines for preventing travellers' diarrheas.

Adult↗
PubMed1998

[Vaccination against diarrheal diseases and typhoid fever. Current status and prospects].

Diarrheal diseases and typhoid fever are still common in developing countries and there is still a search for effective control measures able to prevent the epidemics they cause from time to time. There are recommended preventive measures based on health education and improvement of sewage and water facilities; however these recommendations given for many years have not reached the expected results for different reasons. Antibiotherapy was very effective for many years; unfortunately increasing antibiotic resistance has been reported, particularly in Shigella and typhoid fever treatment. This explains the re-kindled interest currently taking place in vaccines development against infections due to V. cholerae, Shigella, E.coli ETEC, S. typhi and rotavirus. The new available vaccines are very effective and provide greater protection than that given by the old killed injectable vaccines. They paved the way for development of new candidate vaccines easier to deliver (oral vaccines or one dose parenteral vaccine), which already give promising results. Some of these candidate vaccines like those related to Shigella infections are considered as a future promising tool for controlling diarrhea due to Shigella.

Adult↗
PubMed1997

Pertussis: a worldwide problem.

Pertussis is a serious disease for children in all countries, but it is more severe in the developing world. Disease incidence, complication rates and case fatality rates are highest in infants: unimmunized and incompletely immunized young children are also at risk in adults, pertussis is usually mild or asymptomatic, but older individuals may serve as reservoirs for transmission. Some 70 million cases of pertussis were prevented in 1994 due to immunization with the current whole cell vaccine. WHO emphasizes the importance of early completion of the primary series of vaccinations, with three doses of diphtheria-tetanus-pertussis (DTP) vaccine one month apart starting at six weeks of age. For the past five years, nearly 80% of infants worldwide have received three DTP doses by their first birthday. Despite this, an estimated 40 million cases of pertussis occurred in 1994, indicating the need to increase coverage. The challenge is to reach 90% coverage of infants in all countries by the year 2000 but this will require further efforts to improve immunization programmes.

Adolescent↗
PubMed1997

The WHO Global Programme for Vaccines and Immunization Vaccine Trial Registry.

In 1995, the WHO Global Programme for Vaccines and Immunization established a Vaccine Trial Registry. As of September 1996, this registry included 50 WHO-supported vaccine trials, of which 25 (50%) were completed studies. The vaccines most frequently tested have been against measles (9 trials), poliovirus (8 trials), cholera (8 trials), enterotoxigenic Escherichia coli (4 trials), and pneumococcus (4 trials). Nearly 80% of these trials have been conducted in developing countries, with the largest number being in Africa. Among the 25 completed trials, outcomes measured were immune response (24 trials), adverse reactions (13 trials), morbidity (4 trials), and mortality (1 trial). WHO's contributions to these studies include direct funding, assistance with study design, site visits, data analysis, vaccine procurement, and vaccine potency testing.

Adolescent↗
PubMed1994

Vaccination against typhoid fever: present status.

Typhoid fever remains an underestimated important health problem in many developing countries, causing more than 600,000 deaths annually in the world. Because of the reactogenicity of the parenteral, killed whole-cell vaccine, research has been oriented towards vaccination orally using live organisms and purified antigen. Live vaccine Ty21a, given by the oral route, has been extensively tested in several studies in developing countries. Its liquid formulation was the most effective, providing more than 60% protection after 7 years of follow-up. A Vi polysaccharide vaccine has been elaborated and provided more than 65% protection; after 3 years of follow-up the Vi antibody level was still at a high level. These two vaccines are therefore candidates for use in public health control programmes. Before such use, however, they need further evaluation for safety and protective efficacy when administered to the EPI-targeted age groups. The question of whether typhoid fever vaccines interfere with the response to simultaneously administered measles vaccine must also be studied. New live vaccines, given by the oral route in one dose, have been constructed through genetic engineering. The first results are promising, but they must be improved before use in a large-scale study. These strains could be used as live vector to deliver foreign antigens to the intestinal mucosa.

Administration, Oral↗
PubMed1989

Chlamydial antibodies and tubal infertility.

Prevalence of Chlamydia trachomatis antibodies was studied in infertile women with and without tubal obstruction, and in a control group of pregnant women in a Central-African country with a high infertility rate. In comparison with the control group, tubal infertility patients were significantly more likely to have serum antibodies of 1:64 or greater with an age-adjusted odds ratio of 7.8 (95% confidence interval (CI) 3.2-19.1). Infertile women without tubal obstruction had antibody titres similar to the control group with an odds ratio of 1.1 (95% CI: 0.6-1.9). In the tubal infertility group there was a kind of dose-response relationship between chlamydial antibodies and the severity of tubal damage and pelvic adhesions on laparoscopy, with odds ratios of 3.2 (95% CI: 0.7-14.8), 6.2 (95% CI: 1.9-21.6) and 18.1 (95% CI: 6.0-68.5) in the group with mild, moderate and severe pelvic adhesions respectively. This survey adds more evidence to the hypothesis that C. trachomatis is a major agent responsible for tubal infertility in Central Africa.

Adult↗
PubMed1988

Infertility in Central Africa: infection is the cause.

Determinants of infertility were studied in 340 women in Eastern Gabon, an area situated in the "infertility belt" of Central Africa. Fallopian tube occlusion was diagnosed in 82.8% of cases, showing the importance of infection-related causes. Women with tubal occlusion did not differ significantly from women with normal tubes in obstetrical history or prevalence of Neisseria gonorrhoeae or Chlamydia trachomatis on endocervical culture. Antecedents of pelvic inflammatory disease or a pelvic mass were significantly more common in the group with tubal occlusion. This group also had a significantly higher prevalence of serum chlamydial antibodies at a titer of 1/64 or higher. Hormonal factors were found in 31.7% of women, a cervical factor in 29.0% and mechanical factors in 5.6%. No diagnosis could be made in 12.2% of cases. During the investigation, 4.4% of women became pregnant. The predominance of infectious related causes of infertility makes it imperative to focus resources on prevention programs of upper genital tract infections in women.

Adult↗