[Modern methods for surveillance of communicable disease: general introduction (author's transl)]. / Les méthodes modernes de surveillance des maladies transmissibles: introduction générale.

Epidemiological surveillance has now become a fully developed discipline, to which several technical specialties contribute. All kinds of new problems resulting from present conditions of life have enlarged the field of surveillance beyond the old concept of morbidity-mortality. This has necessitated the application of new methodology--a stimulating challenge for those who are engaged in epidemiological surveillance.

[International surveillance of some viral diseases (author's transl)]. / Surveillance internationale de certaines maladies à virus.

During a period of more than fifteen years the WHO international surveillance system for selected viral diseases has been modified on several occasions. The aims of the surveillance programme on viral diseases are two-fold: to make available world-wide epidemiological information and to contribute to the development of public health laboratories in countries where this is necessary.

[International influenza surveillance (author's transl)]. / Surveillance internationale de la grippe.

Influenza may be considered a convenient model to set up a methodology for surveillance in a country, which can further be extended to other diseases. The solidarity which exists among Directors of National Influenza Centres is one of the reasons for its success. On positive result, and one which is not negligible, has been the stimulating effect which influenza surveillance had on the development of virus laboratories in tropical regions.

[Arboviral diseases: a field where research and public health call for international cooperation (author's transl)]. / Les arboviroses: un domaine ou la santé publique et la recherche appellent une cooperation internationale.

Arboviral diseases constitute a group of infections transmitted to man by hematophagous arthropods: mosquitoes, ticks, sand flies and culicoides. A long period of research has provided only partial insight into their mode of transmission. Arboviruses can cause influenza-like diseases, haemorrhagic fevers, and encephalitides. As a result of the different clinical manifestations and their complex mode of transmission, they give rise to public health problems which are usually severe and difficult to solve, and which may result in extensive and deadly epidemics. Fortunately, these problems have motivated international cooperation in scientific research and in the solution of public health problems, a unique example in the field of virology.

[Minor arboviral diseases in Central and West Africa (author's transl)]. / Les arboviroses mineures en Afrique centrale et occidentale.

Many arboviruses can cause febrile illness in man, with or without rash, quite apart from yellow fever and the aetiological agents of haemorrhagic fevers. Exanthema are one of the commonest signs. Neuro-vascular attacks frequently occur and in some cases meningitic complications can happen. Diagnosis is often difficult: viraemia is of short duration and complement fixing antibodies do not appear consistently in convalescent serum. In Central and West Africa, 19 different arboviruses have been implicated either by isolation or by serological conversion. Some were isolated from man for the first time.

Immunizations in developing countries.

The WHO Expanded Programme on immunization has greatly improved the prevention of 6 major diseases of infants in developing countries, but a number of other immunizations are left aside. They concern diseases which are either specific to tropical countries or common to both developed and developing countries. Preventive immunization programmes against these diseases are often non-existent and countries rely on "fire-fighting" immunization campaigns whenever an outbreak occurs. This deficiency is the result of logistic difficulties, most of which could be overcome. Recent progress in research will bring improved classical vaccines and new vaccines which are eagerly awaited. However, logistic problems in developing countries will have to be solved to make the best use of multiple antigens which will soon be at hand.

[Recent Lassa, Marbourg and Ebola viruses in African tropical viruses. I. Semiology--physiopathology--diagnosis--treatment (author's transl)]. / Les virus Lassa, Marbourg et Ebola, nouveaux venus en pathologie tropicale africaine. I. Sémiologie--Physio-pathologie--Diagnostic--Traitement.

Three new viruses have been identified in Africa during the present decade. They may cause sporadic cases or limited outbreaks, and they are probably endemic in areas which are still ill-defined. Severe forms of infection lead to the haemorrhagic syndrome or to hypovolemic shock, the physiopathology of which is being studied. The case-fatality ratio of severe cases is between 30 and 85 per cent. Nosocomial outbreaks have been observed, but they can be avoided if appropriate barrier nursing measures are carried out for the treatment of patients or adequate protection measures for sampling and examination of laboratory specimens. As such cases may be transferred outside the endemic zone, this implies that countries receiving travellers from Africa should have hospitals with specialized units for strict isolation and treatment of these patients.

[Lassa, Marbourg and Ebola viruses: new features of African tropical pathology. II. Epidemiology. Public health problems (author's transl)]. / Les virus Lassa, Marbourg et Ebola: nouveaux venus en pathologie tropicale africaine. II. Epidémiologie-Problèmes de santé publique.

Lassa, Marbourg and Ebola viruses are characterised by their endemo-epidemicity in tropical Africa, by their potential of inter-human transmission, by their gravity (30 to 50% mortality in cases admitted to hospital) and by the difficulty of their aetiological diagnosis. This results in a public health problem for countries in non-endemic regions receiving travellers coming from Africa. This problem is related to the risk of importation of cases, a risk which should not be exaggerated but nor should it be underestimated. Appropriate measures may be suggested in the light of assessment of the risk: organisation of specialised hospital facilities, laboratory and coordination service.

A century of progress in combating yellow fever.

Yellow fever was responsible for several epidemics among the settlers in tropical areas of the Americas and Africa during the 17th to the 19th centuries. Scientific research into its cause and epidemiology was started at the beginning of the present century and progressed well ahead of other viral disease research. However, epidemics still occur and the worst one ever recorded was in Ethiopia in 1960-62. Epidemiological research has recently provided new findings on the ecology of the virus and the risk of epidemics. Recent breakthroughs in the molecular study of the virus should provide new tools for further progress in treatment and control of the disease. Meanwhile, the risk of urbanization of the disease, deficiencies in treatment, limitations in vector control, and erratic policies in preventive immunization present real problems.

In vitro susceptibilities of Coxiella burnetii, Rickettsia rickettsii, and Rickettsia conorii to the fluoroquinolone sparfloxacin.

In vitro susceptibilities of Rickettsia rickettsii, Rickettsia conorii, and Coxiella burnetii to the new fluoroquinolone sparfloxacin (AT-4140; RP 64206) were determined. Plaque and dye uptake assays were used to measure the MICs against R. rickettsii and R. conorii. The susceptibilities of C. burnetii Nine Mile and Q 212 were determined in two acute-infection models and in two chronic-infection models. The MICs were 0.125 to 0.25 microgram/ml for R. rickettsii and 0.25 to 0.5 microgram/ml for R. conorii. Sparfloxacin (1 microgram/ml) cured cells recently infected with C. burnetii Nine Mile and Q 212 within 4 to 9 days and cured multiplying, persistently infected cells within 10 days. As previously described with other fluoroquinolones (D. Raoult, M. Drancourt, and G. Vestris, Antimicrob. Agents Chemother. 34:1512-1514, 1990), sparfloxacin failed to cure cells persistently infected with C. burnetii and blocked from dividing with cycloheximide. As determined by the dye uptake assay, no cellular toxicity was noted with sparfloxacin at up to 128 micrograms/ml. These results are consistent with those previously obtained with fluoroquinolones (D. Raoult, M. Yeaman, and O. Baca, Rev. Infect. Dis. 11[Suppl. 5]:S986, 1989), although sparfloxacin may be slightly more active.

Ontogeny of yellow fever 17D vaccine: RNA oligonucleotide fingerprint and monoclonal antibody analyses of vaccines produced world-wide.

Yellow fever 17D vaccines are currently manufactured with approval of the World Health Organization (WHO) in 11 countries. These vaccines have proven highly efficacious and safe. Nevertheless, they have not been fully characterized genetically, a problem for future standardization and modernization of vaccine manufacture now being proposed by WHO. Vaccines in use are derived from two distinct substrains (17D-204 and 17DD) which represent independently maintained passage series from original 17D. In this study, all 17D vaccines produced world-wide were characterized by RNA oligonucleotide fingerprinting. Forty-two large oligonucleotides were compared, and differences from an arbitrarily selected reference strain (produced by Connaught Laboratories in the U.S.A.) were determined. With one exception (vaccine produced in South Africa), fingerprints of vaccines derived from substrain 17D-204 were identical. The South African primary seed differed in position of one oligonucleotide, reflecting a charge shift due to a single base change. This difference occurred within one egg passage; a further change in the South African vaccine occurred within one or two passages from primary seed. No antigenic differences between 17D-204-derived vaccines (including South Africa) were demonstrated by neutralization tests using monoclonal antibody. Vaccines derived from the 17DD substrain consistently differed from 17D-204 vaccines in the absence of one oligonucleotide (No. 37). This change probably occurred during 40 additional egg passages in development of the 17DD vaccines. A clear antigenic difference was shown between 17D-204 and 17DD substrain vaccines using monoclonal antibody. 17DD vaccines showed minor genotypic differences, suggesting a higher degree of genetic instability than 17D-204 vaccines. No oligonucleotide fingerprint differences were found between avian leukosis virus (ALV)-free and ALV-contaminated vaccines. No definite genomic correlate of neurovirulence was defined by fingerprinting strains with a history of encephalitic complications in man or of failure to pass monkey neurovirulence tests. Parent Asibi virus showed several oligonucleotide differences and was serologically distinct from 17D vaccine.

Epidemiological aspects of the 1969 yellow fever epidemic in Nigeria.

The Virus Research Laboratory of the University of Ibadan, Nigeria, was notified on 23 October 1969 that cases of suspected yellow fever had occurred in the Jos area. The diagnosis was confirmed by virus isolation and the existence of a widespread outbreak on the Jos Plateau and adjacent areas was established. This was the first recognized epidemic of yellow fever in Nigeria since 1953. Between September and the end of December 1969, an estimated total of 252 patients with yellow fever were hospitalized. The case-fatality ratio for hospitalized patients was approximately 40%. The diagnosis of yellow fever was confirmed by virus isolation, serology, or pathology in 55 patients. It is estimated that up to 100 000 cases of yellow fever may have occurred during the epidemic.

The use of jet-injectors in BCG vaccination.

In mass vaccination programmes, the jet-injection of vaccine may have considerable operational advantages over the classical techniques. The technical performance of two models of jet-injector, the Dermo-Jet and the Ped-O-Jet, in BCG vaccination was assessed in a number of studies which are reviewed by the authors. It is shown that the jet-injectors do not administer the full dose for which they are calibrated and that the size of the vaccination lesion varies more than after vaccination by syringe.By increasing the dosage considerably, the results of vaccination by jet-injection may be improved to a certain extent but the risk of unpleasant reactions is also increased.