[Epidemiological aspects of Ebola virus disease in Guinea (december 2013-april 2016)]. / Aspects épidémiologiques de la maladie à virus Ebola en Guinée (décembre 2013­avril 2016).

Ebola Zaire species variant Makona between its emergence in December 2013 and April 2016, resulted in an epidemic of Guinea importance and unprecedented gravity with 3814 reported cases of which 3358 were confirmed (88.0%) and 2544 were died (66.7%). The epidemic has evolved in phases: a silent phase without identification of all fatal cases until February 2014; a first outbreak from March 2014, when the alarm is raised and the virus detected, which lasted until July 2014; a second increase, which was the most intense, from August 2014 to January 2015 focused primarily on the forest Guinea; and a final increase from February 2015 centered on lower Guinea and the capital Conakry. Adapting strategies in 2015 (initiative "Zero Ebola in 60 days" active case search and suspicious deaths and awareness of active prefectures, microbanding the last affected communities and raking around these localities) and ring vaccination of contacts around confirmed cases has allowed to gradually control the main outbreak in October 2015. But a survivor was originally resurgence in forest areas between March and April 2016 with 10 cases including 8 deaths. The epidemic has particularly affected the forest Guinea region (44% and 48% of Guinean cases and deaths), elderly women (≥ 50 years), and health professionals (211 cases including 115 deaths); however, almost one-third of the patients (32.6%) was not provided supportive care in the Ebola centers. The epidemic is currently marked by the resurgence of small foci, from excreting subjects cured of the virus who have been controlled so far successfully. The survivors are the subject of special attention. It is necessary to learn lessons from the response to better prepare for the future, to improve knowledge about the natural history of the Ebola virus disease, and to rethink communication in this regard with the public and its leaders.

Use of hub cutters and the volume of sharp waste and occurrence of needle-stick injuries during 2011 mass immunization campaigns against yellow fever in Ghana: a cohort study.

BACKGROUND: Current WHO best infection control practices for injections do not address the use of hub cutters due to insufficient evidence on safety and efficacy. OBJECTIVE: To assess the impact of the use of hub cutters on 1) the frequency of needle-stick injuries (NSIs) and other blood exposures among workers and 2) the volume of sharps waste in a mass vaccination campaign setting. METHODS: During yellow fever vaccination in Ghana, we conducted a cohort study on the use of hub cutters. We compared two groups---one group using hub cutters and a control group---for the occurrences of NSIs and the volume of sharp waste produced. RESULTS: In the control arm, vaccinators used 284 482 syringes in 825 vaccination sessions. In the group using hub cutter, vaccinators used 397 079 syringes in 1599 sessions. Among vaccinators, the rate of NSI was not significantly (p=0.14) different between the hub cutter users (0.15/10 000 syringes) and the control group (0.04/10 000). Factors such as workload, lack of organization and pressure seemed to have influence the occurrence of NSIs. With all the limitations of the work, the volume of sharp waste per 10 000 syringes was 0.24 m(3) in the hub cutter users and 0.41 m(3) in the control group---a reduction of 41.2%. Vaccinators found hub cutters easy to use and safe. Use of hub cutter was not associated with increased duration of work. CONCLUSION: The use of hub cutters did not increase the risk of NSIs. More training is needed to facilitate its implementation in mass campaign setting.

Adverse events following yellow fever preventive vaccination campaigns in eight African countries from 2007 to 2010.

BACKGROUND: Serious, but rare adverse events following immunization (AEFI) have been reported with yellow fever (YF) 17D vaccine, including severe allergic reactions, YF vaccine-associated neurologic disease (YEL-AND) and YF vaccine-associated viscerotropic disease (YEL-AVD). The frequency with which YEL-AND and YEL-AVD occur in YF endemic countries is mostly unknown. METHODS: From 2007 to 2010, eight African countries - Benin, Cameroon, Guinea, Liberia, Mali, Senegal, Sierra Leone, and Togo- implemented large-scale YF preventive vaccination campaigns. Each country established vaccine pharmacovigilance systems that included standard case definitions, procedures to collect and transport biological specimens, and National Expert Committees to review data and classify cases. Staff in all countries received training and laboratory capacity expanded. RESULTS: In total, just over 38 million people were vaccinated against YF and 3116 AEFIs were reported of which 164 (5%) were classified as serious. Of these, 22 (13%) were classified as YF vaccine reactions, including 11 (50%) hypersensitivity reactions, six (27%) suspected YEL-AND, and five (23%) suspected YEL-AVD. The incidence per 100,000 vaccine doses administered was 8.2 for all reported AEFIs, 0.43 for any serious AEFI, 0.058 for YF vaccine related AEFIs, 0.029 for hypersensitivity reactions, 0.016 for YEL-AND, and 0.013 for YEL-AVD. Our findings were limited by operational challenges, including difficulties in obtaining recommended biological specimens leading to incomplete laboratory evaluation, unknown case ascertainment, and variable levels of staff training and experience. CONCLUSIONS: Despite limitations, active case-finding in the eight different countries did not find an incidence of YF vaccine associated AEFIs that was higher than previous reports. These data reinforce the safety profile of YF vaccine and support the continued use of attenuated YF vaccine during preventive mass vaccination campaigns in YF endemic areas.

A Bayesian network approach to the study of historical epidemiological databases: modelling meningitis outbreaks in the Niger.

OBJECTIVE: To develop a tool for evaluating the risk that an outbreak of meningitis will occur in a particular district of the Niger after outbreaks have been reported in other, specified districts of the country. METHODS: A Bayesian network was represented by a graph composed of 38 nodes (one for each district in the Niger) connected by arrows. In the graph, each node directly influenced each of the "child" nodes that lay at the ends of the arrows arising from that node, according to conditional probabilities. The probabilities between "influencing" and "influenced" districts were estimated by analysis of databases that held weekly records of meningitis outbreaks in the Niger between 1986 and 2005. For each week of interest, each district was given a Boolean-variable score of 1 (if meningitis incidence in the district reached an epidemic threshold in that week) or 0. FINDINGS: The Bayesian network approach provided important and original information, allowing the identification of the districts that influence meningitis risk in other districts (and the districts that are influenced by any particular district) and the evaluation of the level of influence between each pair of districts. CONCLUSION: Bayesian networks offer a promising approach to understanding the dynamics of epidemics, estimating the risk of outbreaks in particular areas and allowing control interventions to be targeted at high-risk areas.

[From genomics to surveillance, prevention and control: new challenges for the African meningitis belt]. / Ceinture africaine de la méningite: de la génomique aux stratégies de surveillance, de lutte et de prévention.

An international conference was held in Niamey, Niger, in November 2005. It aimed at reviewing the current situation in the meningitis belt. This region stretches from Senegal to Ethiopia and is characterized by high levels of seasonal endemicity with large epidemics of meningococcal meningitis occurring cyclically, generally caused by N. meningiditis serogroup A. WHO currently recommends a reactive strategy based on rapid detection of epidemics, intervention with antibiotics to treat cases and mass vaccination with a meningococcal polysaccharide vaccine to halt the outbreak. Epidemiological patterns of the disease in Africa have been changing with the occurrence of outbreaks outside the meningitis belt and with the emergence of serogroup W135, which first caused an epidemic among Hajj pilgrims in 2000 and then a large-scale meningitis outbreak in Burkina Faso in 2002. Consequently enhanced laboratory surveillance and confirmation of the strain responsible for the outbreak are required. New rapid dipstick tests have been developed through a collaboration between Institut Pasteur and CERMES. They are designed for bedside diagnosis and detect meningococcal antigens present in CSF using immunochromatography. The treatment of meningococcal meningitis during epidemics is based on short-course, long-acting oily chloramphenicol. An alternative is the use of ceftriaxone, which is equally effective and can be used in pregnant women and infants. A low-cost, monovalent serogroup A meningococcal conjugate vaccine for large-scale use in Africa is under development. In spite of the emergence of W135 strains in the meningitis belt, N. meningiditis A continues to be the principal strain isolated during the epidemic seasons and elimination of outbreaks of N. meningiditis serogroup A can still be considered as the primary objective of a preventive vaccination strategy.

Konzo outbreak, in the south-west of the Democratic Republic of Congo, 1996.

In August 1996, cases of poliomyelitis were reported in Kahemba zone, in the south-west of the Democratic Republic (DR) of Congo. The diagnosis was reviewed and charged to Konzo, a spastic paraparesis attributed to food cyanide intoxication. In order to describe the phenomena, a community-based survey took place and found 237 people affected. The highest prevalence was found in the most isolated part of the zone. The patients suffered from an isolated non-progressive spastic paraparesis of abrupt onset. Children and women were the most affected groups, especially women after childbirth. Most of the patients developed the disease after 1990 with 101 cases in 1996. Cassava processing was the same over time and in all the villages. The study did not fully explain the increased number of cases in 1996 but suggested that complementary investigations regarding micronutrient intakes, especially vitamin A, would be necessary.

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.

PIP: This study was undertaken to assess the feasibility of mass vaccination using a two-dose oral cholera vaccine in a refugee setting in Uganda. A total of 44,000 south Sudanese refugees were involved in the study. The campaign was conducted using killed whole-cell/recombinant B-subunit cholera vaccine. Measured outcomes include the total number of doses administered, the dropout rate between the two rounds, the amount of vaccine wasted, the cost of the campaign, and the vaccine coverage. Given the results of the study, the mass vaccination of a refugee population with a two-dose oral cholera vaccine proved to be feasible. A total of 63,220 vaccines were administered, with 200 vaccine doses given per vaccination area per hour. The campaign cost was US$14,655, excluding the cost of the vaccine. Vaccine coverage was 83% for the first round and 75.9% for the second round. A presumptive vaccination strategy could be taken into account in stable refugee settings and in urban slums in high-risk sites. However, the potential amount of the vaccine and the absence of immediately accessible stockpiles are major constraints for its large-scale implementation.

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.

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.