Short Communication Rediscovery of Atelopus cruciger (Anura: Bufonidae): current status in the Cordillera de La Costa, Venezuela

Abstract The genus Atelopus (Anura: Bufonidae) has suffered one of the most drastic declines recorded in the Neotropics. Nine of 10 Venezuelan species are categorized as Critically Endangered on the IUCN Red List. None of these species had been observed since the mid 1980s until recently, when an adult female of Atelopus mucubajiensis and several adults of A. cruciger were rediscovered. To assess the current distribution and status of A. cruciger we explored 15 locations where it was formerly known. Two populations were detected. Historical and current distribution maps were constructed based on these field explorations and data from museum collections. Using PCR assays we detected infection with Batrachochytrium dendrobatidis in one morbid and three live specimens. Our surveys suggest A. cruciger populations from lower altitudes on the northern slope of the Cordillera de La Costa are recovering, although the presence of B. dendrobatidis could jeopardize their long-term survival unless active conservation strategies are adopted

Understanding the potential impact of different drug properties on SARS-CoV-2 transmission and disease burden : a modelling analysis

Q1Q1Background The unprecedented public health impact of the COVID-19 pandemic has motivated a rapid search for potential therapeutics, with some key successes. However, the potential impact of different treatments, and consequently research and procurement priorities, have not been clear. Methods and Findings develop a mathematical model of SARS-CoV-2 transmission, COVID-19 disease and clinical care to explore the potential public-health impact of a range of different potential therapeutics, under a range of different scenarios varying: i) healthcare capacity, ii) epidemic trajectories; and iii) drug efficacy in the absence of supportive care. In each case, the outcome of interest was the number of COVID-19 deaths averted in scenarios with the therapeutic compared to scenarios without. We find the impact of drugs like dexamethasone (which are delivered to the most critically-ill in hospital and whose therapeutic benefit is expected to depend on the availability of supportive care such as oxygen and mechanical ventilation) is likely to be limited in settings where healthcare capacity is lowest or where uncontrolled epidemics result in hospitals being overwhelmed. As such, it may avert 22% of deaths in highincome countries but only 8% in low-income countries (assuming R=1.35). Therapeutics for different patient populations (those not in hospital, early in the course of infection) and types of benefit (reducing disease severity or infectiousness, preventing hospitalisation) could have much greater benefits, particularly in resource-poor settings facing large epidemics. Conclusions There is a global asymmetry in who is likely to benefit from advances in the treatment of COVID-19 to date, which have been focussed on hospitalised-patients and predicated on an assumption of adequate access to supportive care. Therapeutics that can feasibly be delivered to those earlier in the course of infection that reduce the need for healthcare or reduce infectiousness could have significant impact, and research into their efficacy and means of delivery should be a priorityRevista Internacional - Indexad

LA INTRODUCCIÓN DE BUFO MARINUS EN AUSTRALIA: PATRONES, CONSECUENCIAS Y PERSPECTIVAS DE CONTROL

Originario del Neotrópico, el sapo común o Bufo mariinis. abarca hoy 4 de las 6 regiones zoogeográficas de la Tierra, como resultado de introducciones deliberadas, en algunos casos, y accidentales, en otros. En Australia, en donde fue introducida en 1935. alcanza hoy densidades mucho mayores que las reportadas en sus lugares de origen. Aún cuando no se ha demostrado si esta especie e|crcc algún impacto significativo sobre la fauna autóctona Australiana, su enorme éxito reproductivo y gran capacidad de dispersión representan una potencial amenaza para algunas especies nativas. Este artículo resume gran parte de los resultados obtenidos de un programa de investigación para el diseño de estrategias de control para B. niarinii.i en Australia, en el que participaron Australia. Brasil y Venezuela. Estimaciones de algunos de los parámetros demográficos de esta especie en poblaciones en ambos continentes, y resultados obtenidos de un modelo matemático sugirieron que aumentar la mortalidad del estadio adulto es la estrategia más eficiente para reducir significativamente las densidades de B. niariinis en Australia. Como potenciales agentes de control, se aislaron virus del género Ranavirus de sapos provenientes de Venezuela. Sin embargo, la presencia de anticuerpos de Ranavinis en ejemplares Australianos sugiere que este virus pudiera estar presente ya en Australia sin efectos aparentes sobre las poblaciones de sapos. No obstante, la reciente detección de dos linajes bien diferenciados de esta especie, y el hecho de que los virus aislados provienen de ejemplares de un solo linaje, abre la posibilidad de la existencia de otros patógenos en el otro linaje, a los cuales las poblaciones Australianas no han sido expuestas

The impact of ticks on Bufo marinus from native habitats

We analysed the patterns of tick distribution on 2274 adult toads from Venezuela and Brazil, to explore whether these ectoparasites have any impact on the survival of Bufo marinus. A maximum-likelihood analysis showed that aggregation levels of ticks decreased significantly with the mean intensity of infection. This decline could be attributed to a density-dependent reduction of ticks within toads, density-dependent tick-induced toad mortality and/or density-dependent tick-induced changes in toad susceptibility. However, the relationship between the rate of change in tick loads and tick burdens from recaptured toads indicated that neither the loss of ticks within toads nor the toad susceptibility to further infection were dependent upon tick burdens. Therefore, we can indirectly infer that density- dependent tick-induced toad mortality is responsible for the observed decline in aggregation levels with tick age and burdens. On the other hand, a significant negative relationship between tick burdens and the size-specific weight of toads suggested that ticks may also have a significant impact on the patterns of weight deposition of adult toads. This evidence suggests that these ectoparasites may play an important role in regulating the densities of B. marinus in native habitats

Dinámica epidémica del SARS-CoV-2: emergencia, transmisión y control

La pandemia de la COVID-19 no tiene paralelo en la historia moderna, sin embargo, la propagación del virus SARS-CoV-2sigue principios generales y comunes a la de otros patógenos emergentes. La teoría sobre la dinámica de enfermedades infecciosas sugiereque el SARS-CoV-2 probablemente persistirá como un virus endémico y que su demostrada alta transmisibilidad obliga a asumir óptimas yeficientes estrategias de mitigación previa a que una vacuna brinde la posibilidad de su eliminación. La dinámica epidémica de la COVID-19en Venezuela ha tenido un manejo poco eficiente para un patógeno que aún se encuentra en plena propagación y muestra un comportamientoepidemiológico y evolutivo cambiante. La coexistencia futura de medidas de mitigación de este virus, con el restablecimiento de las rutinassociales y económicas, requiere de un sistema amplio y continuo de rastreo y vigilancia epidemiológica y genómica del SARS-CoV-2, queel país debe adoptar urgentemente. En una era de pandemias, los modelos ecológicos y epidemiológicos, así como la vigilancia zoonótica,son claves para la prevención de la emergencia de nuevos patógenos

Genetic relationships among some species groups within the genus Lutzomyia (Diptera: Psychodidae)

Molecular data on Lutzomyia are very scarce, despite the fact that this genus includes all the species involved in the transmission of leishmaniasis in America. We examine the genetic relationships among eight morphologic groups within the Lutzomyia genus and two Brumptomyia species, using nine enzyme loci and the last 285 basepairs of the mitochondrial cytochrome b gene. The structure of the genetic variation among the species analyzed indicated a closer genetic relationship among members of a morphologic group than between members of different groups. The lower levels of variation recorded among these groups compared with that between Brumptomyia and Lutzomyia suggest a subgeneric status for all of these groups, including Psychodopygus. A maximum likelihood tree for the allozyme data and a neighbor-joining consensus tree for the mitochondrial DNA sequences showed a general agreement with morphologic groups, with only minor differences. Nyssomyia, Verrucarum and Micropygomyia formed separate monophyletic groups. Lutzomyia could not be separated from Psathyromyia, and both Migonei species, L. dubitans and L. migonei, grouped in different clades according to the host species they are found on.This study was supported by Consejo Nacional de Investigacions Científicas y Tecnológicas (CONICIT) (No. 96–0001370), the World Health Organization-World Bank (No. 021–007), the Canadian International Development Agency (CIDA), and the Canadian Bureau for International Education (CBIE)

Rediscovery of Atelopus cruciger (Anura: Bufonidae): current status in the Cordillera de La Costa, Venezuela

The genus Atelopus (Anura: Bufonidae) has suffered one of the most drastic declines recorded in the Neotropics. Nine of 10 Venezuelan species are categorized as Critically Endangered on the IUCN Red List. None of these species had been observed since the mid 1980s until recently, when an adult female of Atelopus mucubajiensis and several adults of A. cruciger were rediscovered. To assess the current distribution and status of A. cruciger we explored 15 locations where it was formerly known. Two populations were detected. Historical and current distribution maps were constructed based on these field explorations and data from museum collections. Using PCR assays we detected infection with Batrachochytrium dendrobatidis in one morbid and three live specimens. Our surveys suggest A. cruciger populations from lower altitudes on the northern slope of the Cordillera de La Costa are recovering, although the presence of B. dendrobatidis could jeopardize their long-term survival unless active conservation strategies are adopted

A chytridiomycosis epidemic and a severe dry season precede the disappearance of Atelopus species from the Venezuelan Andes

Chytridiomycosis has been identified as one of the major forces driving global amphibian declines. Between 1988 and 1994, five Atelopus species endemic to the Venezuelan Andes disappeared. We examined histological samples of Andean Atelopus species available in Venezuelan museum collections for the presence of the chytrid fungus Batrachochytrium dendrobatidis. When infection was detected, sympatric species were examined to investigate the occurrence of the pathogen and how widespread it was. Infection with B. dendrobatidis is reported for the first time in Atelopus carbonerensis, A. mucubajiensis and A. sorianoi, Mannophryne cordilleriana and an undescribed Leptodactylus species. The spatio-temporal patterns of prevalence of this pathogen in Atelopus individuals, with all infections concentrated in one year but spread over distant locations, suggest that synchronized epidemic outbreaks occurred in populations of these Atelopus species in the years prior to their disappearances. Local climate data indicate that one of the most severe dry seasons recorded in the region since 1970 coincided with these epidemic events. The climatic-linked epidemic hypothesis seems a plausible explanation for the coincidence between the observed amphibian declines, the chytridiomycosis outbreaks,and the droughts recorded in that area