Dirofilariasis in Argentina: Historical review and first report of <i>Dirofilaria immitis</i> in a natural mosquito population

Argentina is one of the four South American countries where the presence of Dirofilaria immitis is currently confirmed. The objective of this study was to review information on dirofilariasis in the country, and to report our recent findings on mosquito vectors. Since the first report of dogs with unidentified microfilariae in 1926, D. immitis was found in seven provinces and canine prevalence ranged 0–71% at local scale. National prevalence was 8% by the end of the 1980s and current information is available only for Buenos Aires Province. Four pulmonary human infections of D. immitis and one subcutaneous of Dirofilaria sp. were documented. The common coati was the only wild host found, and natural infection in mosquitoes was not previously reported in the country. In our recent mosquito survey in Greater Buenos Aires, we captured and dissected 2380 mosquitoes belonging to 20 species. According to a minimum temperature of 14 8C, the potential transmission period (PTP) for D. immitis in Buenos Aires covers 6 months, and the most favourable period (mean temperature above 20 8C) takes place from the middle of November to the beginning of April. To identify potential vectors of the parasite, we assessed weekly abundances of mosquito species during those PTP estimated previously. We found two specimens of Culex pipiens and one of Aedes aegypti carrying non-infective stages of D. immitis. These two highly anthropophilic mosquitoes may enhance the role of D. immitis as zoonotic agent in temperate Argentina.Facultad de Ciencias Veterinaria

Controle de Aedes aegypti com temefós em cemitério de Buenos Aires, Argentina

The efficacy of a larvicide, temephos, for controlling Ae. aegypti was evaluated in a cemetery in Buenos Aires, Argentina. Breeding sites decreased from 18.4% in the first study period (Nov 1998 to May 1999, without temephos) to 2.2% in the second period (Nov 1999 to May 2000, two applications), and to 0.05% in the third one (Nov 2000 to May 2001, five applications). Ovitraps with eggs decreased from 17% in the first period to 5.8% in the second period, and to 2.9% in the third one. Results suggest that, in Buenos Aires, Ae. aegypti populations are highly susceptible to temephos. It is recommended to limit the use of temephos to prevent potential epidemics rather than for routine control.Se evaluó la eficacia de un larvicida, temefós, para controlar Ae. aegypti en un cementerio de Buenos Aires, Argentina. Los criaderos descendieron de 18,4% en el primer periodo de estudio (Nov 1998 a May 1999, sin temefos) a 2,2% en el segundo (Nov 1999 a May 2000, dos aplicaciones), y a 0,05% en el tercero (Nov 2000 a May 2001, cinco aplicaciones). Las ovitrampas con huevos disminuyeron de 17% en el primer periodo a 5,8% en el segundo, y a 2,9% en el tercero. Los resultados sugieren que, en Buenos Aires, las poblaciones de Ae. aegypti son altamente susceptibles al temefós. Es recomendable limitar su uso para prevenir eventuales epidemias y no para el control rutinario.Avaliou-se a eficácia de um larvicida, temefós, para controlar Ae. aegypti em um cemitério de Buenos Aires, Argentina. Os criadouros reduziram de 18,4% no primeiro período de estudo (nov de 1998 a maio de 1999, sem temefós) para 2,2% no segundo (nov de 1999 a maio de 2000, duas aplicações), e para 0,05% no terceiro (nov de 2000 a maio de 2001, cinco aplicações). As. ovitrampas com ovos diminuíram de 17% no primeiro período para 5,8% no segundo e para 2,9% no terceiro. Os resultados sugerem que, em Buenos Aires, as populações de Ae. aegypti são altamente susceptíveis ao temefós. É recomendável seu uso para prevenir eventuais epidemias e não para o controle rotineiro

Dirofilaria en perros y mosquitos del Gran Buenos Aires, ¿qué sabemos luego de 15 años de estudio?

La dirofilariasis canina por Dirofilaria immitis se conoce en Argentina desde 1931. Para el año 2000, la enfermedad estaba reportada en perros de 7 provincias con prevalencias entre 0 y 71%, 4 casos pulmonares humanos, 7 ejemplares de coatí y ningún conocimiento sobre las especies de mosquitos que trasmiten el parásito. Con el objetivo de (1) conocer la prevalencia de la enfermedad en perros y los factores de riesgo, y (2) identificar a las especies de mosquitos que actúan como vectores, durante 2003 iniciamos los estudios en la zona sur del Gran Buenos Aires.Asociación Parasitológica Argentin

Primer hallazgo del vector del dengue en Tandil y posterior diagnóstico de situación (feb. 2019-agosto 2020): una experiencia colaborativa con la Dirección de Bromatología del municipio

El mosquito vector del dengue, Aedes aegypti, fue registrado en Tandil por primera vez en febrero de 2019 a partir de un hallazgo casual. Luego, se planificó un estudio colaborativo entre el Instituto Ecosistemas y la Dirección de Bromatología para evaluar la situación local desde octubre 2019 a mayo 2020 mediante ovitrampas, búsqueda activa de criaderos y análisis de fotografías y ejemplares enviados por vecinos. Las trampas evidenciaron la presencia del mosquito de mediados de noviembre a fines de abril. Además se demostró la infestación del vector en viviendas, gomerías y un predio municipal. Entre los 484 recipientes con agua revisados, 17 (3,5%) contenían estadios inmaduros del mosquito. El conjunto de evidencias señaló consistentemente la presencia de Ae. aegypti en la zona más urbanizada del municipio. La presente experiencia permitió obtener un diagnóstico de situación sólido con muy pocos recursos. El vector del dengue está establecido en la ciudad y estarían dadas las condiciones para que haya transmisión local de la enfermedad durante futuras epidemias de escala nacional. Con el conjunto de resultados se elaboró un informe técnico y se entregó alMunicipio y al HCD de Tandil, y entre mayo y septiembre 2020 se realizaron 15 actividades de divulgación entre charlas web, prensa escrita y entrevistas radiales de medios locales

An epidemiological study of gastrointestinal parasites of dogs from Southern Greater Buenos Aires (Argentina): Age, gender, breed, mixed infections, and seasonal and spatial patterns

A total of 2193 fecal samples from owned dogs were collected during the 2003–2004 period in Southern Greater Buenos Aires, and were evaluated for the presence of intestinal parasites by a flotation–centrifugation method. The overall prevalence was 52.4%, and the 11 species found were: Ancylostoma caninum (13%), Isospora ohioensis complex (12%), Toxocara canis (11%), Trichuris vulpis (10%), Sarcocystis sp. (10%), Giardia duodenalis (9%), Isospora canis (3%), Hammondia–Neospora complex (3%), Dipilydium caninum (18 cases), Cryptosporidium sp. (5 cases), and Toxascaris leonina (1 case). There was no significant difference in the overall prevalence between genders (female = 50.4%, male = 54.6%), and breeds (pure = 52.3%, mixed = 53%), but prevalence in puppies (&lt;1 year) was higher than in adult dogs (62.7% versus 40.8%, respectively). Only the prevalence of A. caninum differed between genders, with higher values for males. The prevalences of six of the parasite species showed a decreasing trend with increasing host age, and an inverse pattern was found for two other species. The prevalences of three protozoa were significantly higher in pure-breed dogs, and those of two nematodes were significantly higher in mixedbreed dogs. The prevalences of T. canis, A. caninum, and T. vulpis were spatially heterogeneous with a clear Southwest– Northeast gradient. Only prevalences of Sarcocystis sp. and G. duodenalis showed seasonal variation. The frequency distribution of the number of species per fecal sample did not differ from a random distribution. Results obtained throughout the world were discussed.Facultad de Ciencias Veterinaria

PCR detection of Dirofilaria immitis in <i>Aedes aegypti</i> and <i>Culex pipiens</i> from urban temperate Argentina

Dirofilariasis, a mosquito-borne disease of dogs caused by the nematode Dirofilaria immitis (Leidy; Spirurida: Onchocercidae), has now become a growing zoonotic concern. Based on direct microscopical observation, Aedes aegypti (L.) and Culex pipiens L. (Diptera: Culicidae) have been previously incriminated as potential vectors of D. immitis in urban temperate Argentina. In this study, an effort was made to provide evidence for this assumption by screening of mosquitoes for D. immitis infection using a polymerase chain reaction (PCR) assay. PCR primers were developed to specifically amplify the D. immitis-16S rRNA gene and to reliably detect 100th of the genomic equivalent (10 pg) of the infective third-stage larvae in mosquito pools of up to 30 individuals. Collection of mosquitoes was performed between September 2007 and April 2008 in premises known to be inhabited by D. immitis-infected dogs in Greater Buenos Aires. The final collection comprised 453 specimens belonging to 11 mosquito species of the genera Aedes, Culex, Ochlerotatus, and Psorophora. PCR assays were performed on 82 pools (n ≤ 20) of heads and abdomens separately, as this allows differentiating infective and non-infective stages of the parasite, respectively. Identification of the non-infective stage of D. immitis in A. aegypti and C. pipiens provided additional strong support of transmission of the parasite by these species. To our knowledge, this was the first PCR screening for D. immitis-infected mosquitoes in South America.Facultad de Ciencias Veterinaria

Dirofilariasis in Argentina: Historical review and first report of <i>Dirofilaria immitis</i> in a natural mosquito population

Argentina is one of the four South American countries where the presence of Dirofilaria immitis is currently confirmed. The objective of this study was to review information on dirofilariasis in the country, and to report our recent findings on mosquito vectors. Since the first report of dogs with unidentified microfilariae in 1926, D. immitis was found in seven provinces and canine prevalence ranged 0–71% at local scale. National prevalence was 8% by the end of the 1980s and current information is available only for Buenos Aires Province. Four pulmonary human infections of D. immitis and one subcutaneous of Dirofilaria sp. were documented. The common coati was the only wild host found, and natural infection in mosquitoes was not previously reported in the country. In our recent mosquito survey in Greater Buenos Aires, we captured and dissected 2380 mosquitoes belonging to 20 species. According to a minimum temperature of 14 8C, the potential transmission period (PTP) for D. immitis in Buenos Aires covers 6 months, and the most favourable period (mean temperature above 20 8C) takes place from the middle of November to the beginning of April. To identify potential vectors of the parasite, we assessed weekly abundances of mosquito species during those PTP estimated previously. We found two specimens of Culex pipiens and one of Aedes aegypti carrying non-infective stages of D. immitis. These two highly anthropophilic mosquitoes may enhance the role of D. immitis as zoonotic agent in temperate Argentina.Facultad de Ciencias Veterinaria

Evidences on a new species of the genus Dirofilaria in dogs from Neuquén, Argentina

La dirofilariasis canina en Argentina se extiende desde la provincia de Buenos Aires hacia el norte. En todos los casos documentados, el agente etiológico es el gusano del corazón del perro, Dirofilaria immitis, única especie del género identificada como causal de infecciones naturales autóctonas en el país. En este estudio, se presentan evidencias morfológicas, serológicas y moleculares de la infección de otra especie del género Dirofilaria en 8 perros de la ciudad de Neuquén, en el extremo norte de la Patagonia. Las microfilarias observadas tuvieron una media de 370 mm de largo y 7,1 mm de ancho. Las secuencias obtenidas mostraron homologías inferiores al 95 % con otras secuencias de filáridos reportadas en el GenBank.Canine dirofilariasis in Argentina extends from Buenos Aires province to the North. All documented cases were due to the dog heartworm, Dirofilaria immitis, the unique species recorded in natural infected dogs in the country. In this study, we present morphologic, serologic and molecular evidences of the infection with another Dirofilaria species in 8 dogs from Neuquén city, in the northern extreme of Patagonia. The observed microfilariae had a mean of 370 mm long and 7.1 mm wide. The sequences obtained showed homologies lower than 95 % with other filarid sequences reported in the Genbank.Facultad de Ciencias Veterinaria

An epidemiological study of gastrointestinal parasites of dogs from Southern Greater Buenos Aires (Argentina): Age, gender, breed, mixed infections, and seasonal and spatial patterns

A total of 2193 fecal samples from owned dogs were collected during the 2003–2004 period in Southern Greater Buenos Aires, and were evaluated for the presence of intestinal parasites by a flotation–centrifugation method. The overall prevalence was 52.4%, and the 11 species found were: Ancylostoma caninum (13%), Isospora ohioensis complex (12%), Toxocara canis (11%), Trichuris vulpis (10%), Sarcocystis sp. (10%), Giardia duodenalis (9%), Isospora canis (3%), Hammondia–Neospora complex (3%), Dipilydium caninum (18 cases), Cryptosporidium sp. (5 cases), and Toxascaris leonina (1 case). There was no significant difference in the overall prevalence between genders (female = 50.4%, male = 54.6%), and breeds (pure = 52.3%, mixed = 53%), but prevalence in puppies (&lt;1 year) was higher than in adult dogs (62.7% versus 40.8%, respectively). Only the prevalence of A. caninum differed between genders, with higher values for males. The prevalences of six of the parasite species showed a decreasing trend with increasing host age, and an inverse pattern was found for two other species. The prevalences of three protozoa were significantly higher in pure-breed dogs, and those of two nematodes were significantly higher in mixedbreed dogs. The prevalences of T. canis, A. caninum, and T. vulpis were spatially heterogeneous with a clear Southwest– Northeast gradient. Only prevalences of Sarcocystis sp. and G. duodenalis showed seasonal variation. The frequency distribution of the number of species per fecal sample did not differ from a random distribution. Results obtained throughout the world were discussed.Facultad de Ciencias Veterinaria

Comparación preliminar de la microaglutinación microscópica (MAT) con la inmunofluorescencia indirecta (IFI) para la detección de leptospirosis canina

El objetivo del presente trabajo fue comparar las técnicas de MAT e IFI para la detección de anticuerpos en sueros de perros sospechosos de leptospirosis.Facultad de Ciencias Veterinaria