Ecological approaches in veterinary epidemiology: mapping the risk of bat-borne rabies using vegetation indices and night-time light satellite imagery.

Rabies remains a disease of significant public health concern. In the Americas, bats are an important source of rabies for pets, livestock, and humans. For effective rabies control and prevention, identifying potential areas for disease occurrence is critical to guide future research, inform public health policies, and design interventions. To anticipate zoonotic infectious diseases distribution at coarse scale, veterinary epidemiology needs to advance via exploring current geographic ecology tools and data using a biological approach. We analyzed bat-borne rabies reports in Chile from 2002 to 2012 to establish associations between rabies occurrence and environmental factors to generate an ecological niche model (ENM). The main rabies reservoir in Chile is the bat species Tadarida brasiliensis; we mapped 726 occurrences of rabies virus variant AgV4 in this bat species and integrated them with contemporary Normalized Difference Vegetation Index (NDVI) data from the Moderate Resolution Imaging Spectroradiometer (MODIS). The correct prediction of areas with rabies in bats and the reliable anticipation of human rabies in our study illustrate the usefulness of ENM for mapping rabies and other zoonotic pathogens. Additionally, we highlight critical issues with selection of environmental variables, methods for model validation, and consideration of sampling bias. Indeed, models with weak or incorrect validation approaches should be interpreted with caution. In conclusion, ecological niche modeling applications for mapping disease risk at coarse geographic scales have a promising future, especially with refinement and enrichment of models with additional information, such as night-time light data, which increased substantially the model's ability to anticipate human rabies.

[Wildlife veterinarians rabies vaccination in Chile: a survey]. / Encuesta sobre vacunación anti-rábica en veterinarios de fauna silvestre en Chile.

INTRODUCTION: Rabies is a lethal but preventable disease. Knowing the extent of immunization coverage among at risk populations, may help to guide immunization efforts, as well as increase the effectiveness of rabies control and prevention programs. AIM: To determine the proportion of wildlife veterinarians in Chile, as part of a group at risk of rabies transmission. METHODS: An electronic survey was sent to wildlife veterinarians in Chile. RESULTS: We found that veterinarians in Chile work mainly with carnivores and deer compared to other mammals (p < 0.001), rarely works with bats (p = 0.6572). Most of the participants had been bitten by domestic animals, while a lesser proportion (29%) by wild animals. Most of the participants never received rabies vaccination (53%), while within the group that had started a rabies vaccination scheme, a substantial proportion (39%) did not complete it. DISCUSSION AND CONCLUSION: Identify the vaccination status of risk groups is important for infectious disease control and prevention programs, as this information helps to identify priority groups during outbreaks or vaccine scarcity. Wildlife veterinarians in Chile are at risk of rabies transmission and should be included in rabies prevention programs, especially considering their vulnerability and lack of biosafety practices. Increasing education in rabies epidemiology and prevention is urgently needed in veterinary faculties in Chile.

Encuesta sobre vacunación anti-rábica en veterinarios de fauna silvestre en Chile / Wildlife veterinarians rabies vaccination in Chile: a survey

Introduction: Rabies is a lethal but preventable disease. Knowing the extent of immunization coverage among at risk populations, may help to guide immunization efforts, as well as increase the effectiveness of rabies control and prevention programs. Aim: To determine the proportion of wildlife veterinarians in Chile, as part of a group at risk of rabies transmission. Methods: An electronic survey was sent to wildlife veterinarians in Chile. Results: We found that veterinarians in Chile work mainly with carnivores and deer compared to other mammals (p < 0.001), rarely works with bats (p = 0.6572). Most of the participants had been bitten by domestic animals, while a lesser proportion (29%) by wild animals. Most of the participants never received rabies vaccination (53%), while within the group that had started a rabies vaccination scheme, a substantial proportion (39%) did not complete it. Discussion and conclusion: Identify the vaccination status of risk groups is important for infectious disease control and prevention programs, as this information helps to identify priority groups during outbreaks or vaccine scarcity. Wildlife veterinarians in Chile are at risk of rabies transmission and should be included in rabies prevention programs, especially considering their vulnerability and lack of biosafety practices. Increasing education in rabies epidemiology and prevention is urgently needed in veterinary faculties in Chile.

Introducción: La rabia es una enfermedad infecciosa mortal pero prevenible. Establecer si existe una adecuada inmunización pre-exposición contra la rabia en un grupo de riesgo, puede ayudar a enfocar los esfuerzos de inmunización para hacer efectivos los programas de control y prevención de la enfermedad. Objetivo: Determinar mediante una encuesta la proporción de veterinarios de fauna silvestre como grupo de riesgo que han recibido inmunización contra la rabia. Métodos: Se realizó una encuesta electrónica a veterinarios de fauna de vida silvestre de Chile. Resultados: Los veterinarios encuestados tienden a trabajar con carnívoros y ciervos en comparación con otros mamíferos (p < 0,001), rara vez con murciélagos (p = 0,6572). La mayoría de los encuestados había sido mordido por animales domésticos y una proporción menor (29%) por animales silvestres. La mayoría nunca había sido vacunado contra la rabia (53%), mientras que del grupo que sí había recibido vacunación anti-rábica, una importante proporción (39%) no completó el esquema de vacunación. Sorprendentemente, este grupo de profesionales rara vez trabaja con murciélagos (p = 0,6572), lo que puede reducir su exposición a linajes de rabia transmitida por murciélagos. Discusión y Conclusión: Identificar el estado de inmunización contra la rabia en grupos de riesgo es una información importante para evaluar los programas de prevención y control de enfermedades infecciosas y podría ayudar a identificar grupos prioritarios en situaciones de brote o escasez de vacuna. Los veterinarios de fauna de vida silvestre en Chile constituyen un grupo vulnerable: no mantienen prácticas de bioseguridad necesarias y tienen riesgo de adquirir la encefalitis rábica por lo que deberían ser considerados en los programas de prevención pre-exposición de la enfermedad. La educación sobre la epidemiología y prevención de la rabia es urgente en las facultades de medicina veterinaria en Chile.

Bat-borne rabies in Latin America.

The situation of rabies in America is complex: rabies in dogs has decreased dramatically, but bats are increasingly recognized as natural reservoirs of other rabies variants. Here, bat species known to be rabies-positive with different antigenic variants, are summarized in relation to bat conservation status across Latin America. Rabies virus is widespread in Latin American bat species, 22.5%75 of bat species have been confirmed as rabies-positive. Most bat species found rabies positive are classified by the International Union for Conservation of Nature as "Least Concern". According to diet type, insectivorous bats had the most species known as rabies reservoirs, while in proportion hematophagous bats were the most important. Research at coarse spatial scales must strive to understand rabies ecology; basic information on distribution and population dynamics of many Latin American and Caribbean bat species is needed; and detailed information on effects of landscape change in driving bat-borne rabies outbreaks remains unassessed. Finally, integrated approaches including public health, ecology, and conservation biology are needed to understand and prevent emergent diseases in bats.

Bat-borne rabis in latin america / Rabia transmitida por murciélagos en Latino América

The situation of rabies in America is complex: rabies in dogs has decreased dramatically, but bats are increasingly recognized as natural reservoirs of other rabies variants. Here, bat species known to be rabies-positive with different antigenic variants, are summarized in relation to bat conservation status across Latin America. Rabies virus is widespread in Latin American bat species, 22.5%75 of bat species have been confirmed as rabies-positive. Most bat species found rabies positive are classified by the International Union for Conservation of Nature as “Least Concern”. According to diet type, insectivorous bats had the most species known as rabies reservoirs, while in proportion hematophagous bats were the most important. Research at coarse spatial scales must strive to understand rabies ecology; basic information on distribution and population dynamics of many Latin American and Caribbean bat species is needed; and detailed information on effects of landscape change in driving bat-borne rabies outbreaks remains unassessed. Finally, integrated approaches including public health, ecology, and conservation biology are needed to understand and prevent emergent diseases in bats.

La situación de rabia en América es compleja: la rabia en perros ha disminuido drásticamente pero los murciélagos están siendo reconocidos cada vez más como reservorios naturales de otras variantes de rabia. Aquí compilamos las especies de murciélagos reconocidas como positivas a rabia con diferentes variantes antigénicas, así como su relación con el estado de conservación de los murciélagos a lo largo de América Latina. El virus de rabia está ampliamente distribuido en las especies de murciélagos de América Latina, 22.5% (75) de las especies de murciélagos conocidas han sido confirmadas como especies positivas a rabia. La mayoría de las especies de murciélagos reportadas como positivas a rabia son clasificadas por la Unión Internacional para la Conservación de la Naturaleza como “Preocupación Menor”. De acuerdo al tipo de dieta, los murciélagos insectívoros tuvieron la mayor cantidad de especies reconocidas como reservorio del virus rabia, mientras en proporción los hematófagos fueron los más importantes. Investigaciones a escala gruesa deben buscar entender aspectos de ecología de la rabia; es necesaria la información básica sobre la distribución y dinámica poblacional para muchas especies de murciélagos de América Latina y el Caribe; y el efecto del cambio del paisaje en la generación de brotes de rabia transmitida por murciélagos permanece sin ser evaluado. Por último, para entender y prevenir enfermedades emergentes a partir de los murciélagos es necesario un enfoque integral incluyendo salud pública, ecología y biología de la conservación.

Ecology and geography of transmission of two bat-borne rabies lineages in Chile.

Rabies was known to humans as a disease thousands of years ago. In America, insectivorous bats are natural reservoirs of rabies virus. The bat species Tadarida brasiliensis and Lasiurus cinereus, with their respective, host-specific rabies virus variants AgV4 and AgV6, are the principal rabies reservoirs in Chile. However, little is known about the roles of bat species in the ecology and geographic distribution of the virus. This contribution aims to address a series of questions regarding the ecology of rabies transmission in Chile. Analyzing records from 1985-2011 at the Instituto de Salud Pública de Chile (ISP) and using ecological niche modeling, we address these questions to help in understanding rabies-bat ecological dynamics in South America. We found ecological niche identity between both hosts and both viral variants, indicating that niches of all actors in the system are undifferentiated, although the viruses do not necessarily occupy the full geographic distributions of their hosts. Bat species and rabies viruses share similar niches, and our models had significant predictive power even across unsampled regions; results thus suggest that outbreaks may occur under consistent, stable, and predictable circumstances.

[Immune response of suckling mouse brain (CRL) rabies vaccine and tissue culture rabies vaccine (Verorab) in pre-exposure prophylaxis in humans]. / Evaluación de la capacidad inmunogénica de la vacuna antirrábica tipo Fuenzalida- Palacios (CRL) y de la vacuna antirrábica de cultivo celular (Verorab) en personas con tratamiento preexposición.

BACKGROUND: A WHO experts committee recommended the substitution of antirabic vaccines produced in nervous tissue, by vaccines produced in tissue cultures. AIM: To compare the immunogenic capacity of antirabic vaccines CRL (produced in nervous tissue) and Verorab (produced in tissue culture), used for pre-exposure prophylaxis in humans. PATIENTS AND METHODS: Fifty four volunteers were immunized for this study. The first group, vaccinated with CLR was treated with a scheme of 4 subcutaneous peri umbilical doses in days 0, 3, 7 and 28. The second group, vaccinated with Verorab vaccine was treated with a scheme of 3 intramuscular doses in deltoid zone at days 0, 7 and 28. Blood samples were obtained at days 0, 7, 42 and 365 to measure neutralizing antibodies using the Inhibition of Fluorescent Focus Technique (RFFIT). RESULTS: At day seven, a primary non protective immunologic response was observed in both groups, with titers significantly higher in the group vaccinated with Verorab. At day 42, no differences were observed. At day 365, all subjects vaccinated with Verorab and 50% of individuals vaccinated with CRL had protective antibody titers (p <0.05). CONCLUSIONS: The vaccine produced in cell breeds (Verorab) produces a better an faster immunologic response compared to the CRL vaccine.

Characterization of rabies virus isolates in Bolivia.

In Latin America, rabies is still an important public health problem. Canine rabies, and wild animal rabies, especially transmitted by hematofagous and insectivorous bats, has become an emerging problem in the countries of this region. We received 363 samples with a laboratory-confirmed rabies diagnosis from Bolivia during l997-2001. From these, we could obtain 222 rabies virus isolates by intra-cerebral inoculation in mice. By antigenic characterization we could identify 147 isolates as variant 1, 2 isolates as variant 2, 3 isolates as variant 3, and 1 isolate as variant 5. Phylogenetic analysis of 84 isolates established that they segregated in 3 different branches, corresponding to 3 genetic variants, 78 isolates corresponding to antigenic variant 1 segregated in the same lineage as the antigenic variant 5, 2 isolates corresponding to antigenic variant 2 segregated in another lineage, and 3 isolates from antigenic variant 3 segregated in a different lineage.The genetic variant that mainly circulates in Bolivia is maintained in a cycle whose main reservoir are dogs, but it is not possible to discard the presence of other cycles, in which different species of bats or other wild mammals could be participating.

First case of human rabies in chile caused by an insectivorous bat virus variant.

The first human rabies case in Chile since 1972 occurred in March 1996 in a patient without history of known exposure. Antigenic and genetic characterization of the rabies isolate indicated that its reservoir was the insectivorous bat Tadarida brasiliensis. This is the first human rabies case caused by an insectivorous bat rabies virus variant reported in Latin America.