Mosquitoes as Vectors of Mycobacterium ulcerans Based on Analysis of Notifications of Alphavirus Infection and Buruli Ulcer, Victoria, Australia.

Alphavirus infections are transmitted by mosquitoes, but the mode of transmission for Mycobacterium ulcerans, which causes Buruli ulcer, is contested. Using notification data for Victoria, Australia, during 2017-2022, adjusted for incubation period, we show close alignment between alphavirus and Buruli ulcer seasons, supporting the hypothesis of mosquito transmission of M. ulcerans.

Assessment of Mayaro virus vector competence of the mosquito Aedes aegypti (Linnaeus, 1762) populations in Argentine using dose-response assays.

Mayaro virus (MAYV; Alphavirus: Togaviridae) is an emerging pathogen in Latin America, causing fever and polyarthritis. Sporadic outbreaks of MAYV have occurred in the region, with reported human cases being imported to Europe and North America. Although primarily a risk for those residing in the Amazon basin's tropical forests, recent reports highlight that urbanization would increase the risk of MAYV transmission in Latin America. Urban emergence depends on human susceptibility and the ability of mosquitos like Aedes aegypti  (Linnaeus, 1762) (Diptera: Culicidae) to transmit MAYV. Despite the absence of active MAYV transmission in Argentine, the risk of introduction is substantial due to human movement and the presence of Ae. aegypti in the region. This study aimed to evaluate the susceptibility of different Argentine Ae. aegypti populations to MAYV genotype L (MAYV-L) using dose-response assays and determine barriers to virus infection, dissemination and transmission. Immature mosquito stages were collected in Buenos Aires, Córdoba and Rosario cities. Female Ae. aegypti (F2) were orally infected by feeding on five concentrations of MAYV-L, ranging from 1.0 to 6.0 log10 PFU/mL. Abdomens, legs and saliva were analysed using viral plaque assays. Results revealed that MAYV-L between infection and dissemination were associated with viral doses rather than the population origin. Infection rates varied between 3% and 65%, with a 50% infectious dose >5.5 log10 PFU/mL. Dissemination occurred at 39%, with a 50% dissemination dose of ~6.0 log10 PFU/mL. Dissemination among infected mosquitoes ranged from 60% to 86%, and transmission from disseminated mosquitoes ranged from 11% to 20%. Argentine Ae. aegypti populations exhibited a need for higher viral doses of MAYV-L than those typically found in humans to become infected. In addition, only a small proportion of infected mosquitoes were capable of transmitting the virus. Understanding MAYV transmission in urban areas is crucial for public health interventions.

Mayaro virus, a potential threat for Europe: vector competence of autochthonous vector species.

BACKGROUND: Mayaro virus (MAYV) is an emerging alphavirus, primarily transmitted by the mosquito Haemagogus janthinomys in Central and South America. However, recent studies have shown that Aedes aegypti, Aedes albopictus and various Anopheles mosquitoes can also transmit the virus under laboratory conditions. MAYV causes sporadic outbreaks across the South American region, particularly in areas near forests. Recently, cases have been reported in European and North American travelers returning from endemic areas, raising concerns about potential introductions into new regions. This study aims to assess the vector competence of three potential vectors for MAYV present in Europe. METHODS: Aedes albopictus from Italy, Anopheles atroparvus from Spain and Culex pipiens biotype molestus from Belgium were exposed to MAYV and maintained under controlled environmental conditions. Saliva was collected through a salivation assay at 7 and 14 days post-infection (dpi), followed by vector dissection. Viral titers were determined using focus forming assays, and infection rates, dissemination rates, and transmission efficiency were calculated. RESULTS: Results indicate that Ae. albopictus and An. atroparvus from Italy and Spain, respectively, are competent vectors for MAYV, with transmission possible starting from 7 dpi under laboratory conditions. In contrast, Cx. pipiens bioform molestus was unable to support MAYV infection, indicating its inability to contribute to the transmission cycle. CONCLUSIONS: In the event of accidental MAYV introduction in European territories, autochthonous outbreaks could potentially be sustained by two European species: Ae. albopictus and An. atroparvus. Entomological surveillance should also consider certain Anopheles species when monitoring MAYV transmission.

Mosquito-transmitted viruses - the great Brazilian challenge

ABSTRACT Arboviruses pose a serious threat to public health worldwide, overloading the healthcare system and causing economic losses. These viruses form a very diverse group, and in Brazil, arboviruses belonging to the families Flaviviridae and Togaviridae are predominant. Unfortunately, the number of arboviruses increases in proportion with factors such as deforestation, poor sanitation, climate changes, and introduction of new viruses like Chikungunya virus and Zika virus. In Brazil, dengue is endemic, along with the presence of other arboviruses. The situation is complicated by the scarcity of diagnostic infrastructure and the absence of approved vaccines for these diseases. Disease control, thus, relies solely on vector control. Therefore, enhanced clinical knowledge and improved general awareness about these arboviruses are indispensable to tackle diagnostic inadequacies.

Fiebre de Chikungunya: enfermedad infrecuente como emergencia médica en Cuba / Chikungunya fever: uncommon disease as a medical emergency in Cuba

Debido a la emergencia en el Caribe por fiebre de Chikungunya, y teniendo en cuenta que no tiene antecedentes en Cuba, además de la situación entomológica que presenta la provincia de Santiago de Cuba, donde existen vectores transmisores de enfermedades, tales como mosquitos Aedes aegypti y Aedes albopictus; se realizó una revisión bibliográfica exhaustiva, para contribuir a la actualización sobre el tema de toda la comunidad médica de la provincia.

Due to the emergency in the Caribbean caused by Chikungunya fever, and keeping in mind that it has no history in Cuba, besides the entomological situation that presents Santiago de Cuba province, where vectors transmitting diseases exist, such as Aedes aegypti and Aedes albopictus mosquitoes, an exhaustive literature review was carried out, to contribute to the updating on the topic of the whole medical community from the province.

Failure to demonstrate experimental vertical transmission of the epidemic strain of Chikungunya virus in Aedes albopictus from La Réunion Island, Indian Ocean

Aedes albopictus was responsible for transmission in the first outbreak of chikungunya (CHIK) on La Réunion Island, Indian Ocean, in 2005-2006. The magnitude of the outbreak on this island, which had been free of arboviral diseases for over 30 years, as well as the efficiency of Ae. albopictus as the main vector, raises questions about the maintenance of the CHIK virus (CHIKV) through vertical transmission mechanisms. Few specimens collected from the field as larvae were found to be infected. In this study, Ae. albopictus originating from La Réunion were orally infected with a blood-meal containing 10(8) pfu/mL of the CHIKV epidemic strain (CHIKV 06.21). Eggs from the first and second gonotrophic cycles were collected and raised to the adult stage. The infectious status of the progeny was checked (i) by immunofluorescence on head squashes of individual mosquitoes to detect the presence of viral particles or (ii) by quantitative RT-PCR on mosquito pools to detect viral RNA. We analysed a total of 1,675 specimens from the first gonotrophic cycle and 1,709 from the second gonotrophic cycle without detecting any viral particles or viral RNA. These laboratory results are compared to field records.

Preparação e resposta à introdução do vírus Chikungunya no Brasil / Preparation and response to introduction of Chikungunya virus in Brazil / Preparación y respuesta a la introducción del virus Chikungunya en Brasil

O CHIKV é um vírus RNA que pertence ao gênero Alphavírus da família Togaviridae. O nome chikungunya deriva de uma palavra em Makonde que significa aproximadamente “aqueles que se dobram”, descrevendo a aparência encurvada de pacientes que sofrem de artralgia intensa. Casos humanos com febre, exantema e artrite aparentando ser CHIKV foram relatados no início de 1770. Porém, o vírus não foi isolado do soro humano ou de mosquitos até a epidemia na Tanzânia de 1952-53. Outros surtos ocorreram subsequentemente na África e na Ásia. Muitos ocorreram em pequenas comunidades ou comunidades rurais. No entanto,na Ásia, cepas de CHIKV foram isoladas durante grandes surtos urbanos em Bangkok eTailândia em 1960 e em Calcutá e Vellore, na Índia, durante as décadas de 60 e 70.

Amenaza del virus Chikungunya: la globalización de las enfermedades transmitidas por insecto vector / The Chikungunya threat: the globalization of vectorborne diseases

El brote de infección Chikungunya (CHIKV) que se produjo en el verano de 2007 en una zona templada del norte de Italia, constituye un nuevo modelo para la difusión de una enfermedad tropical fuera de los lugares convencionales, esta situación ha sido causada principalmente, por la peligrosa mezcla de la gran población de un competente vector, el mosquito tigre de Asia, y la posibilidad de que una persona regrese de la zona de la difusión normal de CHIKV durante la fase de viremia asintomática. Teniendo en cuenta las dificultades para controlar la propagación de Aedes albopictus y el gran número de personas que viajan hacia y desde los ámbitos de la difusión normal de las enfermedades transmitidas por vectores tropicales, pensamos que la epidemia de 2007 podría ser sólo la primera de una serie de posibles brotes. En conclusión, esta epidemia urbana de la infección CHIKV en un país templado, determina una nueva perspectiva en la preparación para las inesperadas infecciones emergentes por el virus, las que deben ser afrontadas mediante una estrategia combinada de difusión de vigilancia de vectores, y el diagnóstico inmediato de cualquier caso sospechoso de importación transmitido por vectores de enfermedades exóticas.

The outbreak of CHIKV infection that occurred in summer 2007 in a temperate area of northern Italy constitues a new model for the diffusion of a tropical disease outside the conventional locations; this situation has been caused mainly by the dangerous mixture of the large population of a highly competent vector, the Asian tiger mosquito, and the possibility that an individual comes back from the area of normal diffusion of CHIKV during the asymptomatic viremic stage. Considering the difficulties in controlling the spread of Aedes albopictus and the large number of people travelling to and from the areas of normal diffusion of vector-borne tropical diseases, we think that the 2007 epidemic could be only the first of a possible series of these aoutbreaks. In conclusion, this urban epidemic of CHIKV infection in a temperate country determines a new perspective in the preparedness to unexpected emerging virus infections that must be faced by using a combined strategy of vector diffusion monitoring and immediate diagnosis of any suspected cases of imported vector-borne exotic disease.

Fiebre importada por el virus de Chikungunya / Imported fever due to Chikungunya virus

INTRODUCCIÓN. La patología importada es un retodiagnóstico para el clínico, para el epidemiólogo y las autoridades sanitarias, ya que en algunas circunstancias representarán un riesgo para la comunidad. MÉTODO. Se describe una paciente con enfermedad importada por el virus de Chikungunya. RESULTADOS. Diagnóstico confirmado mediante test específicos en muestras pareadas. CONCLUSIONES. Se comunica la existencia de esta enfermedad importada. Y el peligro que estos enfermos, en condiciones de viremia y en zonas con prevalencia del vector, puedan dar lugar a brotes autóctonos (AU)

INTRODUCTION. Imported diseases pose a diagnostic challenge for the physician, epidemiologists, and the local health care authorities, implying a risk for the community in some cases. METHOD. We report the case of a patient with Chikungunyavirus infection in Spain and describe the clinical and epidemiological characteristics of this condition. RESULTS. Diagnosis was confirmed by specific tests inpaired samples. CONCLUSIONS. The vector for the disease (Aedes albopictus) now exists in Spain. There is a danger that local outbreaks may occur where there are patients with viremia in areas with a prevalence of the vector (AU)

Preparación y respuesta ante la eventual introducción del virus chikungunya en las Américas / Preparation and response to the eventual introduction of the virus Chikungunya in the Americas

Las siguientes guías fueron concebidas para ser adaptadas por cada País Miembro para mejorar los conocimientos sobre esta amenaza y para brindar las herramientas necesarias que permitan establecer las estrategias más adecuada para prevenir la importación de CHIKV a la Región, o para su control. Proporcionan orientación sobre cómo detectar un brote de la enfermedad, desarrollar las investigaciones epidemiológicas y prevenir o mitigar la diseminación de la enfermedad en la Región. Alentamos a las personas involucradas en la aplicación de estas guías a tener en cuenta todos los conocimientos disponibles y la capacidad propia de cada país para afrontar la eventual introducción del CHIKV. Se deben tomar medidas cuanto antes para poner en marcha las acciones necesarias para disminuir el impacto que este nuevo arbovirus que puede existir en nuestra Región.