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Introduction: Since March 11, 2020, Côte d'Ivoire has been affected by the coronavirus epidemic, declared that same day as pandemic by WHO. March 11, 2021, one year after the pandemic, Côte d'Ivoire has notified 36,824 cases of Covid-19 patients and among them 211 have died. As of May 31, 2020, Côte d'Ivoire had already notified 2,833 cases and 33 deaths. At that time, false rumors were circulating in Africa about the setting up of clinical trials on candidate vaccines. The impact of these rumors on the overall use of health services had to be measured and in particular on vaccination centers., Objectives: The objective of this study was to determine the effects of the pandemic on the activities of the immunization services of the National Institute of Public Hygiene in Abidjan, which comprises four departments: International Vaccination Center, Community Vaccination Service, Rabies Center, and Vaccination Unit of the Expanded Program on Immunization. The study was based on activity reports of the immunization services., Results: At the International Vaccination Center, activities fell by about 50% in March, 86% in April and 82% in May in comparison with 2018 and 2019. Activities of Community Vaccination Service decreased by about 26% in March and 99% in April and May. At the Rabies Control Center, this reduction was estimated at 38% in April and 45% in May. The highest losses were for yellow fever and meningitis vaccines., Conclusion: The drop in attendance at vaccination services could increase the risk of epidemics, especially yellow fever, which are recurrent in Abidjan. Intensive awareness and catch-up actions should be carried out and further studies performed to assess the impact of the pandemic on immunization activities., Competing Interests: Les auteurs ne déclarent aucun conflit d'intérêt., (Copyright © 2021 SFMTSI.)

Yellow fever is still a current threat? Yellow fever is a mosquito-borne disease. Africa is the major endemic zone, although there have been epidemics of concern in South America in the last 3 years, especially in Brazil. The virus causes a febrile hepatitis, which can lead to hemorrhagic complications and death. Diagnosis is based on non-specific serological tests. There is no curative treatment. Prevention relies on protection against mosquito bites and on vaccination with a live attenuated vaccine. WHO recommends only one dose of vaccine but data from the literature about life-long protection are divergent on that point, and travel medicine French authorities still recommend a second dose in most at-risk situations., Competing Interests: E. Oliosi déclare n’avoir aucun lien d’intérêts. É. Caumes déclare des liens ponctuels avec Nukleus et Takeda. (vérif. au BAT)

Arboviruses are viral diseases transmitted by mosquitoes and tics bites. They are a major cause of morbidity and sometimes mortality. Their expansion is constant and due in part to climate change and globalization. Mostly found in tropical regions, arboviruses are sometimes the source of epidemics in Europe. Recently, the Chikungunya virus and the Zika virus were responsible for very large epidemics impacting populations that had never been in contact with those viruses. There are currently no effective antiviral treatments or vaccines. Ocular manifestations due to those infections are thus more frequent and increasingly better described. They are sometimes, as with Zika, complicated by a congenital ocular syndrome. The goal of this review is to describe the ophthalmological manifestations of Dengue fever, Chikungunya virus, Zika virus, West Nile virus, and yellow fever., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Introduction: In August 2010, five positive cases of yellow fever were reported in the region of Séguéla, in the northwest of Côte d'Ivoire, affected by an armed conflict since 2002. In order to evaluate the extent of yellow fever virus circulation and the risk for local people, a multidisciplinary investigation was carried out by the Côte-d'Ivoire Ministry of Health and Public Hygiene., Methods: Theses investigations were conducted in the villages of confirmed cases and the outpatient and hospitalization centers attended by infected patients, two weeks after the reactive immunization campaign performed in order to stop the spread of the epidemic. The search for suspects identified 16 cases, including 4 cases and 2 deaths in hospital registers and 12 cases during community interviews, including 6 deaths., Results: Stegomyiens indices were relatively low. Aedes aegypti was present among adult mosquitoes. In addition, three wild vectors, varying in number from one locality to another, were detected: Ae. africanus, Ae. luteocephalus and Ae. vittatus with average biting rates of 0.3; 0.1 and 0.05 bite/man/twilight, respectively, at Soba, Ae. africanus and Ae. vittatus with average biting rates of 0.25 and 0.3 bite/man/twilight, respectively, at Yaokro and Ae. luteocephalus with one bite/man/twilight at Kaborékro., Discussion: Unfortunately, the vaccine response conducted before investigations did not stop progression of the epidemic which broke out three months later in the Worofla health area, close to the Magrékros encampment.

This prospective survey, conducted at the Dakar airport from August 18, 2011, to May 8, 2012, asked a sample of travelers living in France and returning there after a stay in Senegal to complete a questionnaire. The aim of the study was to assess the determinants of vaccination coverage against yellow fever. The study included 10 298 travelers, with a median age of 48 years (interquartile range: 27-58); 52% were tourists, and 22% were traveling for business purposes. The measured level of anti-yellow fever vaccination coverage was 39.3%. Vaccination coverage was influenced by the travelers' level of knowledge and their perception of the risk.

In April 2008, seven years after the outbreak of 2001, Abidjan faced another epidemic of yellow fever. Three weeks after the case detected in the commune of Treichville at 28(th) of April 2008, two other cases were notified, the first one in Port-Bouet and the second one in Cocody located respectively in the south and north of the city of Abidjan. In order to determine a large-scale risk of urban yellow fever epidemic, epidemiological and entomological investigations were conducted by the Ministry of Health and Public Hygiene of Cote d'Ivoire with the support of the Global Outbreak Alert and Response Network. Entomological investigations revealed the predominance of Aedes ægypti, urban vector of yellow fever in neighborhood visited with larval density indices between 2 and 5, indicating the existence of a sufficient density of the vector for cause an explosion of the epidemic. In fact, the massive influx of people from inside cities towards Abidjan caused by the socio-political crisis occurred in the country in 2002, the deterioration of environment with the creation of more breeding sites of Ae. ægypti as corollary and the circulation of the virus at mosquito level were many factors favorable to the yellow fever outbreak in Abidjan city.

In November 2009, ten suspicious cases of yellow fever, including six deaths, were notified in the region of Denguélé, in the northwest of Côte-d'Ivoire. In order to evaluate the extent of yellow fever virus circulation and the risk for local people, a mission of entomological investigation was carried out by the Ministry of Health and Public Hygiene of Côte-d'Ivoire. Entomological investigations were conducted in the villages of confirmed cases (Banakoro and Tron-Touba) and the centers of consultation and hospitalization of cases during illness. Breteau index and recipient index were quasi nil. Aedes aegypti was absent among the captured mosquitoes. On the other hand, Aedes luteocephalus and Aedes opok were present at Banakoro and Tron-Touba with respective average biting rates of 0.8 and 0.6 bite/man/twilight. This situation of epidemic in the northwest of Côte-d'Ivoire could be explained by the deterioration of Denguélé region's health system which is a consequence of the war started in the country in 2002 and which has lowered the immunity of the population.

Resurgence of yellow fever epidemics in Côted'Ivoire remains a major problem of public health. To describe this disease through the early alarm system of National Institute of Public Hygiene (NIPH) is convenient to us. This is a cross-sectional study with descriptive aiming, which proceeded with epidemiological surveillance service of NIPH. The data were collected over 7 years (from 2001 to 2007), starting from the cards of notification, reports, and registers of the service. The main findings of our study are that: 1) we listed 1468 suspect cases including 41 confirmed and the lethality rate was 17.07% among the confirmed cases; 2) most cases of yellow fever were recorded between the years 2001 and 2007; 3) confirmed cases of yellow fever were above 15 years old in 83% of cases. This could be explained by absence of immunization during this age period; 4) recrudescence of cases was observed during the rainy season (June-July and September-October) and the principal vector was Aedes aegypti; 5) data analysis revealed a mean level of 79% for completude and 57%for promptitude of notification; these rates are inferior to WHO norms and; 6) average time of vaccine response post-epidemic was 31 days. Late response is due to difficulties in supplying vaccines. Reinforcement of epidemiological surveillance, prevention by mass immunization, and measurements of hygiene and cleansing are essential to slow down the evolution of this disease.

Despite the existence of antiamaril vaccine in the routine Expanded Program of Immunization (EPI) in Burkina Faso, yellow fever cases still occur in the country. In collaboration with WHO, the national health authorities set up a surveillance system through the national reference laboratory in Centre Muraz (Bobo-Dioulasso). All samples of feverish icterus cases of the 63 health districts of the country were analysed in this lab for M Immunoglobulin using Enzyme Linked Immunosorbent Assay (Elisa). Positive Elisa samples were sent to Pasteur Institute of Dakar (Senegal) for confirmation using a Reverse Transcriptase Polymerase Chain Reaction (RT-PCR) assay. From 2003 to 2005, the number of confirmed cases of yellow fever was respectively of 1/413 (0.24%), 14/616 (2.27%) and 19/618 (3.07%). This increasing of the proportion was statistical different. Then, from 2006 to 2008, the confirmed case proportion was respectively 0.35%, 0.27 and 0.54% without significant difference (P = 0.69). The entomological investigations conducted in 2004 in Bobo-Dioulasso showed that the water pots constitute 48.11% mosquitoes lodgings, followed by metal drums with a strong representation of Culex quinquefasciatus (48.7%), followed by Aedes aegypti (43.3%), as vectors in domestic areas with sectorial variations. These results suggest that more attention must be paid by the national health authorities and international community regarding this disease.

In April 2008, Abidjan was again faced with another case of yellow fever after the epidemic of 2001 causing mass immunization campaign. In order to evaluate the extent of amaril virus circulation and the risk for local people, an entomological investigation was carried out by the Ministry of Health and Public Hygiene of Côte d'Ivoire. At "Entent" area of Treichville, Breteau index was estimated at 34, recipient index at 20% and house index at 25%. Those indexes were respectively 53, 21 and 31% at "Vridi canal" of Port Bouet. In the both neighborhood, Aedes aegypti accounted for more than 80% of mosquitoes caught and more than 90% of mosquitoes adults obtained from larval breeding. This new situation of epidemic risk could be explained by several factors including the reception of 70% of forced migration people caused by the crisis in the country occurred in 2002, the probable drop of preventive immunization, the environment deterioration creating of more breeding sites of Ae. aegypti.

Over 500million people live in yellow fever (YF) endemic areas and more than 3million travel to endemic countries every year. Prevention against YF, caused by the YF virus, an arbovirus, can only be efficiently obtained by active immunization. The vaccine is well tolerated and severe adverse events are very rare. Exceptionally, YF vaccination may result in serious adverse events, such as viscerotropic and neurotropic diseases, sometimes with a fatal outcome. These rare serious adverse advents are reviewed with their potential risk factors, such as advanced age or history of thymus disease. The benefit/risk ratio remains in favour of vaccination, although the decision to offer yellow fever vaccination, especially to persons 60years of age or older, should be evaluated according to the planned trip. Additional research investigations should be made on the host immune response since this response is considered to be at the origin of these severe adverse events.

The aim was to undertake a pilot study of integrated surveillance of yellow fever (YF) in Senegal, based on i) a human surveillance involving healthcare centers in the 11 administrative regions of the country ii) an entomological surveillance including domestic and sylvatic environment and iii) screening mosquitoes for YF virus using RT-PCR method. The integrated approach of human and entomological surveillance was conducted for 2 years (2003-2004). Surveillance in human population was based on screening samples of YF suspected cases (i.e. patients with acute (< or = 15 days) febrile illness with jaundice) for YF specific IgM antibodies. The entomological surveillance was carried out by collecting mosquitoes using human landing catch method and attempt to detect YF virus on them by RT-PCR. Forty five percent of the healthcare centres notified at least one suspected YF case during 2003-2004 periods. Among the 342 sera collected over 2 years, 2 revealed anti-YF IgM antibodies leading to investigations which allowed identification of the source and place of infection and implementation of a reactive focused YF immunization campaign. In addition, YFV was detected by RT-PCR from 49 out of 1762 mosquitoes tested and distributed as follows: in the sylvatic environment, 29 from Aedes furcifer and 1 from Aedes aegypti while in the domestic area, 15 Aedes aegypti and 4 Aedes furcifer. RT-PCR was found more sensitive and rapid than viral isolation for YF virus detection in mosquitoes. The pilot study in Senegal for YF surveillance integrating human and entomological parameters in domestic and sylvatic areas showed that this approach is very efficient in detecting yellow fever virus circulation due to the complementarity of the two systems. Therefore, in the light of the encouraging results presented herein, similar studies in different context and areas are needed to further validate and allow the extension of its application to other endemic regions of Africa.

Yellow fever is a potentially epidemic arboviral disease, submitted to the international health regulation. The disease is severe but rare in travellers. Immunization protects the individual and prevents transmission to non immune populations. Neurological side effects of the vaccine are rare and already known. More recently severe systemic side effects have been reported, with a seemingly age increasing incidence (1,8/100,000 in the over 60 years old). They seem related to host immunity rather than to an increased virulence of the vaccines. The indication and contra indications to the vaccine must be followed strictly according to the benefit/side effects ratio and to the epidemiology.