clove and West-Nile-Fever

In Madagascar, the high West Nile virus (WNV) antibody prevalence reported in horse populations suggests a high level of vector-horse contact. This study aims to characterize the mosquito species usually involved in WNV transmission in horse stables in Madagascar. Five horse stables were investigated in October and November 2016 in five distinct inland areas. Mosquitoes were collected using double net traps baited with human, poultry or horse as well as light traps. Blood meal identification from engorged females was performed using host-specific PCRs. A total of 2898 adult mosquitoes were collected with Culex (Culex) antennatus (Becker) (40.7%), and Cx. (Cux.) quinquefasciatus Say (14.9%), being the most abundant species. The mosquito abundance varied between horse stables (P < 10

Topics: Animals; Cattle; Cattle Diseases; Culex; Culicidae; Female; Horse Diseases; Horses; Madagascar; Mosquito Vectors; West Nile Fever; West Nile virus

West Nile fever (WNF) is a zoonotic disease, occurring nearly globally. In Madagascar, West Nile virus (WNV) was first detected in 1978 from wild birds and the virus is currently distributed across the island, but no epidemic or epizootic period has been recorded. One fatal human case of WNV infection was reported in 2011, suggesting a "tip of the iceberg" phenomenon of a possible WNF epidemic/epizootic on the island. The main objective of this literature-based survey is to review patterns of WNV circulation in Madagascar from the entomological and ornithological points of view. Among the 235 mosquito species described from Madagascar, 29 species are widely associated with WNV infection; 16 of them are found naturally infected with WNV on the island and categorized into major, candidate, and potential vectors of WNV according to their vector capacity. This study upholds the hypothesis that WNV enzooticity is independent of annual movements of migratory birds passing through Madagascar. Moreover, the lack of regular migratory bird flux between Africa and Madagascar would reduce the probability of transmission and the subsequent reintroduction of the virus into locally occurring mosquito species. Given that Palearctic migratory birds are strongly implicated in the transmission of WNV, we highlight notable differences in the movements and species diversity of these birds in Madagascar as compared to eastern and northern Africa. Risk factors from this two-pronged approach are presented for the emergence of WNF outbreak.

Topics: Animal Migration; Animals; Bird Diseases; Birds; Disease Outbreaks; Humans; Madagascar; Mosquito Vectors; Risk Factors; West Nile Fever; West Nile virus

Mitochondrial antiviral signaling protein (MAVS) is a critical innate immune signaling protein that directs the actions of the RIG-I-like receptor (RLR) signaling pathway of RNA virus recognition and initiation of anti-viral immunity against West Nile virus (WNV). In the absence of MAVS, mice die more rapidly after infection with the pathogenic WNV-Texas (TX) strain, but also produce elevated WNV-specific IgG concomitant with increased viral burden. Here we investigated whether there was a B cell intrinsic role for MAVS during the development of protective humoral immunity following WNV infection. MAVS-/- mice survived infection from the non-pathogenic WNV-Madagascar (MAD) strain, with limited signs of disease. Compared to wildtype (WT) controls, WNV-MAD-infected MAVS-/- mice had elevated serum neutralizing antibodies, splenic germinal center B cells, plasma cells and effector T cells. We found that when rechallenged with the normally lethal WNV-TX, MAVS-/- mice previously infected with WNV-MAD were protected from disease. Thus, protective humoral and cellular immune responses can be generated in absence of MAVS. Mice with a conditional deletion of MAVS only in CD11c+ dendritic cells phenocopied MAVS whole body knockout mice in their humoral responses to WNV-MAD, displaying elevated virus titers and neutralizing antibodies. Conversely, a B cell-specific deletion of MAVS had no effect on immune responses to WNV-MAD compared to WT controls. Thus, MAVS in dendritic cells is required to control WNV replication and thereby regulate downstream humoral immune responses.

Topics: Adaptor Proteins, Signal Transducing; Animals; Antibodies, Neutralizing; Antibodies, Viral; B-Lymphocytes; Dendritic Cells; Immunity, Cellular; Immunity, Humoral; Immunity, Innate; Madagascar; Mice; Mice, Inbred C57BL; Mice, Knockout; Signal Transduction; T-Lymphocytes; Texas; Virus Replication; West Nile Fever; West Nile virus

Human and animal serological surveys suggest that West Nile virus (WNV) circulation is widely distributed in Madagascar. However, there are no reported West Nile fever outbreaks or epizootics in the country and only one fatal human case has been reported to date. Currently there is very limited information on the maintenance and the transmission of WNV in Madagascar and particularly on the mosquito species involved in transmission cycles. In 2014, we initiated a study to investigate mosquito species composition, relative abundance, and trophic behavior in Mitsinjo District close to Lake Kinkony, a WNV endemic area in north-western Madagascar. We collected a total of 2519 adult mosquitoes belonging to 21 different species. The most abundant species was Aedeomyia (Aedeomyia) madagascarica Brunhes, Boussès & da Cunha Ramos, which made up 83% of all the mosquitoes collected. Mosquito abundance was associated with proximity to the lake (Morafeno and Ankelimitondrotra). Additionally, a correlation was observed between the lake-side biotope and the abundance of mosquito vectors in Morafeno. WNV RNA was detected in one pool of Ae. madagascarica and one pool of Anopheles (Cellia) pauliani Grjebine, suggesting that these two species may be involved in the maintenance and/or transmission of WNV in Madagascar.

Topics: Animal Migration; Animals; Animals, Domestic; Antibodies, Viral; Bird Diseases; Birds; Cattle; Chickens; Dogs; Endemic Diseases; Feeding Behavior; Female; Lakes; Madagascar; Mosquito Vectors; Population Dynamics; Rats; Seroepidemiologic Studies; Sheep; Swine; West Nile Fever; West Nile virus

West Nile virus is an arthropod-borne zoonosis transmitted by a large number of mosquito species, and birds play a key role as reservoir of the virus. Its distribution is largely widespread over Africa, Asia, the Americas and Europe. Since 1978, it has frequently been reported in Madagascar. Studies described a high seroprevalence level of the virus in humans in different areas of the island and a human fatal case of WNV infection was reported in 2011. Despite these reports, the epidemiology of WNV in Madagascar, in particular, viral circulation remains unclear. To explore the transmission of WNV in two rural human populations of Madagascar, we investigated local mosquitoes and poultry for evidence of current infections, and determined seroprevalence of candidate sentinel species among the local poultry. These 2 areas are close to lakes where domestic birds, migratory wild birds and humans coexist. Serological analysis revealed WNV antibodies in domestic birds (duck, chicken, goose, turkey and guinea fowl) sampled in both districts (Antsalova 29.4% and Mitsinjo 16.7%). West Nile virus nucleic acid was detected in one chicken and in 8 pools of mosquitoes including 2 mosquito species (Aedeomyia madagascarica and Anopheles pauliani) that have not been previously described as candidate vectors for WNV. Molecular analysis of WNV isolates showed that all viruses detected were part of the lineage 2 that is mainly distributed in Africa, and were most closely matched by the previous Malagasy strains isolated in 1988. Our study showed that WNV circulates in Madagascar amongst domestic birds and mosquitoes, and highlights the utility of poultry as a surveillance tool to detect WNV transmission in a peri-domestic setting.

Topics: Animals; Animals, Domestic; Birds; Culicidae; Madagascar; Prevalence; Seroepidemiologic Studies; West Nile Fever; West Nile virus

Abstract. A 58-year-old woman living in Reunion Island and returning from Madagascar was hospitalized for neuroinvasive encephalitis and died 1 month later. West Nile virus (WNV) infection was biologically confirmed by detection of immunoglobulin M (IgM) reactive with WNV antigens in both cerebrospinal fluid and serum, and weak neutralizing activity was also detected. A veterinary survey performed in her traveling area showed a seroprevalence of WNV of 28.7% (95% confidence interval [CI] = 21.1-36.3) in adult poultry, confirming an active circulation of the virus. Development of a severe form could be related to a weak antibody response, because the patient presented low IgM and IgG titers. This case report underlines the constant risk of emergence of West Nile in Indian Ocean territories, including Reunion Island where competent vectors are widely present during the whole year.

Topics: Aedes; Animals; Culex; Fatal Outcome; Female; Humans; Immunoglobulin M; Insect Vectors; Madagascar; Middle Aged; Poultry; Poultry Diseases; Reunion; Travel; West Nile Fever; West Nile virus

The ring-tailed lemur (Lemur catta) is an endangered species found in southwestern Madagascar, and understanding infectious disease susceptibility is an essential step towards the preservation of wild and captive lemur populations. Lemurs are primates that are widely dispersed throughout the island of Madagascar and may serve as hosts or reservoirs for zoonotic infections. The aim of this study was to determine the prevalence of antibodies to West Nile virus (WNV), simian immunodeficiency virus (SIV), and herpes simplex virus type 1 (HSV-1) in a population of free-ranging ring-tailed lemur from the Beza Mahafaly Special Reserve, Madagascar. Samples were collected from 50 animals during field capture studies in June and July 2004 and assayed for presence of viral antibodies during the 12 mo following collection. Forty-seven of the 50 lemurs sampled had antibodies against WNV detectable by epitope-blocking enzyme-linked immunosorbent assay (ELISA). In addition, 50 of 50 samples had titers against WNV ranging from 80 to > or = 1,280 using plaque reduction neutralization test (PRNT(90)). Ten lemurs had antibodies against lentiviral antigens as determined by Western blot analysis. None of the lemurs had antibodies against HSV-1 using ELISA.

Topics: Animals; Animals, Wild; Antibodies, Viral; Conservation of Natural Resources; Flavivirus; Herpesviridae; Lemur; Lentivirus; Madagascar; Seroepidemiologic Studies; Simian Acquired Immunodeficiency Syndrome; Simian Immunodeficiency Virus; West Nile Fever; West Nile virus

The wide geographic distribution of the West Nile virus and the increase in virulence observed since 1994 in the Mediterranean basin, central Europe and North America, with several outbreaks of lethal encephalitis, demonstrate the importance of regular surveillance of the epidemiological data regarding this virus in the world. The Institut Pasteur de Madagascar has shown between 1975 and 1990 that this arbovirus was most abundant in Madagascar, where it had an endemic circulation. There has been no further study since that time. In order to evaluate the level of circulation, the seroprevalence of anti-West Nile antibodies in children that are 15 or less was measured on two different collections of sera. These collections came from population studies realised respectively in the region of Ambositra in the Highlands in 1996 and in the city of Mahajanga on the north west coast in 1999. The seroprevalence were 2.1% and 10.6% respectively, these results indicate that the circulation of this climatic dependent virus is still significant.

Topics: Academies and Institutes; Adolescent; Age Distribution; Animals; Antibodies, Viral; Child; Child, Preschool; Climate; Endemic Diseases; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoglobulin G; Infant; Insect Vectors; Madagascar; Male; Population Surveillance; Residence Characteristics; Rural Health; Seroepidemiologic Studies; Sex Distribution; Urban Health; West Nile Fever; West Nile virus

In 1990 a serological investigation among 3,177 children (5 to 20 years old) sera has been conducted by the Pasteur Institute of Madagascar in several areas of Madagascar, in order to evaluate the prevalence of West Nile virus antibodies. 29.9% out of human sera tested by ELISA for West Nile IgG antibodies are positive, that shows a rather high level of West Nile virus circulation in Madagascar. Prevalence is increasing with age but no significant difference has been registered among prevalence according to sex. The diffusion of the virus appears lighter in Central Highlands.

Topics: Adolescent; Adult; Age Factors; Antibodies, Viral; Child; Enzyme-Linked Immunosorbent Assay; Female; Humans; Immunoglobulin G; Madagascar; Male; Prevalence; Sex Factors; West Nile Fever; West Nile virus

The antigenic relationship of 53 MADAGASCAR West Nile isolates to each other and to the two prototype viruses (Eg 101 and G 2266) was assessed using monoclonal antibodies. In MADAGASCAR exist 5 antigenic groups: 4 which are much closer to the Egyptian strain Eg 101 than to the Indian, and antigenically distinct from South african H 442 strain. One other is closely related to Indian strain G 2266. Antigenic variations are observed in every periods of transmission cycle. Some differences between strains isolated in a same region are also observed. MADAGASCAR is an exchange place for West Nile virus through the instrumentality of migratory birds.

Topics: Aedes; Animals; Antibodies, Monoclonal; Antigenic Variation; Antigens, Viral; Birds; Ceratopogonidae; Disease Vectors; Fluorescent Antibody Technique; Humans; Insect Vectors; Madagascar; Parrots; Serotyping; West Nile Fever; West Nile virus

Virological, serological and entomological research conducted in Madagascar since 1975, reveal the wide-spread presence of West-Nile virus on the island. This arbovirus has been isolated from humans, parrots and egrets. Vectors belong to the genus Culex (e.g. Cx. decens, Cx. quinquefasciatus, Cx. antennatus, Cx. univittatus), however the virus has also been isolated from Aedes and Anopheles. Serological tests carried out on over 1,600 human and almost 1,000 animal sera, revealed that human beings could be infected throughout the island. Other potential vertebrate hosts, apart from birds, are oxen and bats. Insectivores, rodents and lemurs are probably involved in the transmission cycles only to a very small extent.

Topics: Animals; Antibodies, Viral; Birds; Carrier State; Culex; Culicidae; Humans; Insect Vectors; Madagascar; Togaviridae Infections; West Nile Fever; West Nile virus

In previous serological surveys of lemurs in Madagascar, antibodies against flaviviruses were frequently detected. To examine the epidemiological role of Lemur fulvus, experimental infections with yellow fever (YF) virus and West Nile (WN) virus were performed. YF and WN infections were clinically unapparent. A 3 to 4-day-long viremia, with moderate levels was observed with YF virus. WN virus, especially the strain isolated in Madagascar, provoked a 4 to 6-day-long viremia sufficient to infect Aedes aegypti. In all experiments, the antibody response was studied during the following weeks by 3 methods. The results led to the conclusion that Malagasy lemurs could act as amplifying hosts for WN virus present in Madagascar, and as hosts for YF virus if it were introduced on the island. The epidemiological role of these primates is discussed according to their ecology and their contact with potential mosquito vectors in forest areas of Madagascar.

Topics: Aedes; Animals; Antibodies, Viral; Culex; Culicidae; Insect Vectors; Lemur; Lemuridae; Madagascar; Mice; Togaviridae Infections; West Nile Fever; West Nile virus; Yellow Fever; Yellow fever virus

Topics: Aedes; Animals; Arthropod Vectors; Bird Diseases; Birds; Horse Diseases; Horses; Humans; Madagascar; West Nile Fever; West Nile virus