Investigation of a mpox outbreak in Central African Republic, 2021-2022.

Human monkeypox virus is spreading globally, and more information is required about its epidemiological and clinical disease characteristics in endemic countries. We report the investigation of an outbreak in November 2021 in Central African Republic (CAR). The primary case, a hunter, fell ill after contact with a non-human primate at the frontier between forest and savannah. The ensuing investigation in a small nearby town concerned two families and four waves of inter-human transmission, with 14 confirmed cases, 11 suspected cases and 17 non-infected contacts, and a secondary attack rate of 59.5% (25/42). Complications were observed in 12 of the 19 (63.2%) confirmed and suspected cases with available clinical follow-up data: eight cases of bronchopneumonia, two of severe dehydration, one corneal ulcer, one abscess, two cutaneous superinfections, and six cutaneous sequelae (cheloid scars, or depigmentation). There was one death, giving a case fatality ratio of 1/25 (4.0%) for confirmed and suspected cases. This outbreak, with the largest number of confirmed cases ever described in CAR, confirms the potential severity of the disease associated with clade I monkeypox viruses, and highlights the need for rapid control over virus circulation to prevent the further national and international spread of infection.

Investigation of an outbreak of monkeypox in an area occupied by armed groups, Central African Republic.

BACKGROUND: Monkeypox is a zoonosis caused by an Orthopoxvirus of the Poxviridae family. Human infections are often severe and are a public health problem. PATIENTS AND METHOD: We conducted a monkeypox outbreak investigation of suspected case patients in five villages of the Alindao-Mingala Health District following blood sample confirmation of the virus by the Institut Pasteur in Bangui. We aimed to determine disease characteristics, to describe the context and the risk factors, and to measure the incidence and case fatality. Patients were reported in the villages of Rehou 4, 5, Dalakere 1, Kongbo, and Pavika from August to October 2016. Data was collected on individual records when interviewing patients or parents. RESULTS: A total of 26 patients were identified. The˂10 years and 21-30 years age groups were the most affected. The overall attack rate was 5 per 1000 inhabitants and the case fatality was 7.7%. Young age and the absence of smallpox vaccination were associated with severe presentations in 87.5% of cases. CONCLUSION: The annual number of monkeypox outbreaks increases in the Central African Republic with severe presentations and a high case fatality especially in children. Reinforcing the surveillance and characterization of circulating strains will provide information on the need for vaccine production.

New introduction and spread of rabies among dog population in Bangui.

Rabies is endemic in the Central African Republic (CAR) and a neglected enzootic disease which represents a serious public health problem. Before April 2009, rabies was not a notifiable disease in CAR. Vaccination of animals is expensive and not commonly done. In 2005, none rabies case was recorded in Bangui. To understand how rabies was introduced and propagated in the city of Bangui from 2006 to 2008, we analyzed samplings of dog brain as well as reviewed the records of dog owners. A total of 86 out of 101 samples (84.8%) tested positive for rabies virus during this period. Previous phylogenetic analysis of some strains circulating in Bangui between 2006 and 2008 indicated that virus of cosmopolitan and Africa 2 clade are found. Given the time frame and location of these samples, one possible explanation for this alarming result may be that two different strains of rabies virus were introduced at different times in Bangui. Stray dogs are solely responsible for the spread of the epidemic.

[The Chikungunya virus]. / Le virus Chikungunya.

Chikungunya virus (CHIKV), a member of the Alphavirus genus, represents a real public health problem in tropical regions of the Southeast Asia and Africa. It is transmitted to the man by Aedes mosquitoes and the illness, known as Chikungunya, is characterized by fever, eruptions and invalidating arthralgia. An increased surveillance in tropical and subtropical areas is necessary, as far as we have noticed recently the emergence of this new disease in regions where it had never existed before. The epidemic context is of a high importance for diagnosis. It is very important to know the clinical characteristics of the infection, to detect forms rarely or never described previously. Permanence of a highly technical core in specialized laboratories will allow, fast, specific and differential diagnosis. The knowledge of the epidemiological chain of transmission from reservoir, still unknown, to the host aims to protect populations by limiting the risks of exposure when it is possible. The only prevention measures available are individual protection against mosquitoes and antivectorial fight, in the absence of specific antiviral treatment and vaccine.

Serological surveillance of brucellosis and Q fever in cattle in the Central African Republic.

No data are available concerning the seroprevalence of brucellosis in Central African Republic (CAR) and the last report concerning the seroprevalence of Q fever in CAR is from 1995. The aim of our study was to determine the prevalence of these diseases in CAR, especially in Zebu cattle. We used the Rose Bengal Plate Test to test 2032 bovine serum samples for antibodies to Brucella spp. and an indirect immunofluorescence assay to test 784 bovine serum samples for antibodies to Coxiella burnetii (the species responsible for Q fever). The mean seroprevalences of antibodies to Brucella and Coxiella were 3.3 and 14.3%, respectively. Significant differences were found between regions and herds for both diseases. However, relation with differences of climate or vegetation were not evident. Therefore, further data are necessary to better understand the epidemiology of these diseases in CAR and evaluate losses to the farmers.

[Forest ecosystems and Ebola virus]. / Ecosystèmes forestiers et virus Ebola.

Despite data collected since the emergence of the Ebola virus in 1976, its natural transmission cycle and especially the nature of its reservoirs and means of transmission are still an enigma. This means that effective epidemiological surveillance and prevention are difficult to implement. The location of outbreak areas has suggested that the reservoir and the transmission cycle of the Ebola virus are closely linked to the rainforest ecosystem. The fact that outbreaks seldom occur suggests the presence of a rare animal reservoir having few contacts with man. Paradoxically, various serological investigations have shown a high prevalence in human beings, especially in forest areas of the Central African Republic (CAR), with no pathology associated. This would appear to suggest a circulation of both pathogenic and non-pathogenic strains as well as frequent contacts with man. The ecological changes resulting from human activity (agriculture and logging) account for the modification of the fauna (movement of rainforest fauna, introduction of savannah species) and could explain a multiplication of contacts. Likewise, it is interesting to note that the centre of outbreaks has always been in areas bordering on forests (ecotone foreset-savannah in the Democratic Republic of Congo, savannah in Sudan). All these considerations have led us to establish a permanent "watch" in areas bordering on forests in the CAR, involving a multidisciplinary approach to the virological study (strain isolation, molecular biology) of the biodiversity of small terrestrial mammals. The results of a study conducted on 947 small mammals has shown for the first time the presence of the Ebola virus genome in two species of rodents and one species of shrew living in forest border areas. These animals must be considered as intermediary hosts and research should now focus on reservoirs in the ecosystem of forest border areas where contacts with man are likely to be more frequent.

Ebola and Marburg virus antibody prevalence in selected populations of the Central African Republic.

With the natural history of the filovirus family seemingly unknown, filovirus ecology in its natural environment remains a rudimentary field of research. In order to investigate the maintenance cycle of filovirus in Central Africa, a study was conducted within the rain forest of the Central African Republic. The epidemiological study determines the frequency and distribution of filovirus seroprevalence in a selected human population. Using an ELISA, serum samples from Pygmy and non-Pygmy populations were tested for Ebola-Zaire virus and Marburg (MBG) virus antibody. Filovirus antibody reacting sera were found in all zones investigated, and in all populations studied (Ebola virus IgG 5.3%; Marburg virus IgG 2.4%). Pygmies appeared to have a significantly higher seroprevalence (P < 0.03) against Ebola-Zaire virus (7.02%) than non-Pygmies (4.2%). MBG virus or related unknown filovirus strains also seem to be present in the western part of Central Africa. MBG virus antibodies were present in different Pygmy groups (ranging from 0.7 to 5.6%, mean 2.05%) and in several non-Pygmy populations (ranging from 0.0 to 3.9%, mean 3.4%) without an overall significant difference between the two groups (P = 0.14). The potentialities of nonpathogenic filovirus strains circulating in the Central African Republic are discussed.

Identification of Ebola virus sequences present as RNA or DNA in organs of terrestrial small mammals of the Central African Republic.

The life cycle of the Ebola (EBO) virus remains enigmatic. We tested for EBO virus in the organs of 242 small mammals captured during ecological studies in the Central African Republic. EBO virus glycoprotein or polymerase gene sequences were detected by reverse transcription PCR in RNA extracts of the organs of seven animals and by PCR in DNA extract of one animal. Neither live virus nor virus antigen was detected in any organ sample. Direct sequencing of amplicons identified the virus as being of the Zaire/Gabon subtype. Virus-like nucleocapsids were observed by electron microscopy in the cytoplasm of the spleen cells of one animal. The animals belonged to two genera of rodents (Muridae; Mus setulosus, Praomys sp1 and P. sp2) and one species of shrew (Soricidae; Sylvisorex ollula). These preliminary results provide evidence that common terrestrial small mammals living in peripheral forest areas have been in contact with the EBO virus and demonstrate the persistence of EBO virus RNA and DNA in the organs of the animals. Our findings should lead to better targeting of research into the life cycle of the EBO virus.