RESUMEN
The reactive type of aggression is regulated mostly by the brain's prefrontal cortex; however, the molecular changes underlying aggressiveness in adults have not been fully characterized. We used an RNA-seq approach to investigate differential gene expression in the prefrontal cortex of bovines from the aggressive Lidia breed at different ages: young three-year old and adult four-year-old bulls. A total of 50 up and 193 down-regulated genes in the adult group were identified. Furthermore, a cross-species comparative analysis retrieved 29 genes in common with previous studies on aggressive behaviors, representing an above-chance overlap with the differentially expressed genes in adult bulls. We detected changes in the regulation of networks such as synaptogenesis, involved in maintenance and refinement of synapses, and the glutamate receptor pathway, which acts as excitatory driver in aggressive responses. The reduced reactive aggression typical of domestication has been proposed to form part of a retention of juvenile traits as adults (neoteny).
Asunto(s)
Agresión , Domesticación , Agresión/fisiología , Animales , Bovinos/genética , Masculino , Corteza Prefrontal , RNA-Seq , Secuenciación del ExomaRESUMEN
Breeding bulls infected with Besnoitia besnoiti may develop sterility during either acute or chronic infection. The aim of this study was to investigate the molecular pathogenesis of B. besnoiti infection with prognosis value in bull sterility. Accordingly, five well-characterized groups of naturally and experimentally infected males were selected for the study based on clinical signs and lesions compatible with B. besnoiti infection, serological results and parasite detection. A broad panel of molecular markers representative of endothelial activation and fibrosis was investigated and complemented with a histopathological approach that included conventional histology and immunohistochemistry. The results indicated the predominance of an intense inflammatory infiltrate composed mainly of resident and recruited circulating macrophages and to a lesser extent of CD3+ cells in infected bulls. In addition, a few biomarkers were associated with acute, chronic or subclinical bovine besnoitiosis. The testicular parenchyma showed a higher number of differentially expressed genes in natural infections (acute and chronic infections) versus scrotal skin in experimental infections (subclinical infection). In subclinical infections, most genes were downregulated except for the CCL24 and CXCL2 genes, which were upregulated. In contrast, the acute phase was mainly characterized by the upregulation of IL-1α, IL-6 and TIMP1, whereas in the chronic phase, the upregulation of ICAM and the downregulation of MMP13, PLAT and IL-1α were the most relevant findings. Macrophages could be responsible for the highest level of gene regulation in the testicular parenchyma of severely affected and sterile bulls, and all these genes could be prognostic markers of sterility.
Asunto(s)
Enfermedades de los Bovinos/fisiopatología , Coccidiosis/veterinaria , Progresión de la Enfermedad , Sarcocystidae/aislamiento & purificación , Enfermedades Testiculares/veterinaria , Testículo/fisiopatología , Animales , Biomarcadores/análisis , Bovinos , Coccidiosis/fisiopatología , Masculino , Enfermedades Testiculares/fisiopatologíaRESUMEN
BACKGROUND: Aggressive behavior is an ancient and conserved trait, habitual for most animals in order to eat, protect themselves, compete for mating and defend their territories. Genetic factors have been shown to play an important role in the development of aggression both in animals and humans, displaying moderate to high heritability estimates. Although such types of behaviors have been studied in different animal models, the molecular architecture of aggressiveness remains poorly understood. This study compared gene expression profiles of 16 prefrontal cortex (PFC) samples from aggressive and non-aggressive cattle breeds: Lidia, selected for agonistic responses, and Wagyu, selected for tameness. RESULTS: A total of 918 up-regulated and 278 down-regulated differentially expressed genes (DEG) were identified, representing above-chance overlap with genes previously identified in studies of aggression across species, as well as those implicated in recent human evolution. The functional interpretation of the up-regulated genes in the aggressive cohort revealed enrichment of pathways such as Alzheimer disease-presenilin, integrins and the ERK/MAPK signaling cascade, all implicated in the development of abnormal aggressive behaviors and neurophysiological disorders. Moreover, gonadotropins, are up-regulated as natural mechanisms enhancing aggression. Concomitantly, heterotrimeric G-protein pathways, associated with low reactivity mental states, and the GAD2 gene, a repressor of agonistic reactions associated with PFC activity, are down-regulated, promoting the development of the aggressive responses selected for in Lidia cattle. We also identified six upstream regulators, whose functional activity fits with the etiology of abnormal behavioral responses associated with aggression. CONCLUSIONS: These transcriptional correlates of aggression, resulting, at least in part, from controlled artificial selection, can provide valuable insights into the complex architecture that underlies naturally developed agonistic behaviors. This analysis constitutes a first important step towards the identification of the genes and metabolic pathways that promote aggression in cattle and, providing a novel model species to disentangle the mechanisms underlying variability in aggressive behavior.
Asunto(s)
Agresión , Transcriptoma , Animales , Conducta Animal , Cruzamiento , Bovinos , Fenotipo , Corteza PrefrontalRESUMEN
BACKGROUND: Bovine besnoitiosis, caused by the apicomplexan parasite Besnoitia besnoiti, is a chronic and debilitating cattle disease that notably impairs fertility. Acutely infected bulls may develop respiratory signs and orchitis, and sterility has been reported in chronic infections. However, the pathogenesis of acute disease and its impact on reproductive function remain unknown. METHODS: Herein, we studied the microscopic lesions as well as parasite presence and load in the testis (pampiniform plexus, testicular parenchyma and scrotal skin) of seven bulls with an acute B. besnoiti infection. Acute infection was confirmed by serological techniques (IgM seropositive results and IgG seronegative results) and subsequent parasite detection by PCR and histological techniques. RESULTS: The most parasitized tissue was the scrotal skin. Moreover, the presence of tachyzoites, as shown by immunohistochemistry, was associated with vasculitis, and three bulls had already developed juvenile tissue cysts. In all animals, severe endothelial injury was evidenced by marked congestion, thrombosis, necrotizing vasculitis and angiogenesis, among others, in the pampiniform plexus, testicular parenchyma and scrotal skin. Vascular lesions coexisted with lesions characteristic of a chronic infection in the majority of bulls: hyperkeratosis, acanthosis and a marked diffuse fibroplasia in the dermis of the scrotum. An intense inflammatory infiltrate was also observed in the testicular parenchyma accompanied by different degrees of germline atrophy in the seminiferous tubules with the disappearance of various strata of germ cells in four bulls. CONCLUSIONS: This study confirmed that severe acute besnoitiosis leads to early sterility that might be permanent, which is supported by the severe lesions observed. Consequently, we hypothesized that testicular degeneration might be a consequence of (i) thermoregulation failure induced by vascular lesions in pampiniform plexus and scrotal skin lesions; (ii) severe vascular wall injury induced by the inflammatory response in the testis; and (iii) blood-testis barrier damage and alteration of spermatogenesis by immunoresponse.
Asunto(s)
Enfermedades de los Bovinos/patología , Coccidiosis/patología , Coccidiosis/veterinaria , Inflamación/patología , Enfermedades Testiculares/patología , Testículo/patología , Animales , Anticuerpos Antiprotozoarios/sangre , Atrofia , Bovinos , Enfermedades de los Bovinos/parasitología , Coccidiosis/inmunología , Coccidiosis/parasitología , ADN Protozoario/aislamiento & purificación , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Inflamación/parasitología , Masculino , Sarcocystidae/genética , Sarcocystidae/inmunología , Sarcocystidae/aislamiento & purificación , Escroto/patología , Túbulos Seminíferos/parasitología , Túbulos Seminíferos/patología , Espermatogénesis , Enfermedades Testiculares/parasitología , Testículo/lesiones , Testículo/parasitologíaRESUMEN
Deforestation, climate change and invasive species constitute three global threats to biodiversity that act synergistically. However, drivers and rates of loss of freshwater biodiversity now and in the future are poorly understood. Here we focus on the potential impacts of global change on freshwater mussels (Order Unionida) in Sundaland (SE Asia), a vulnerable group facing global declines and recognized indicators of overall freshwater biodiversity. We used an ensemble of distribution models to identify habitats potentially suitable for freshwater mussels and their change under a range of climate, deforestation and invasion scenarios. Our data and models revealed that, at present, Sundaland features 47 and 32â¯Mha of habitat that can be considered environmentally suitable for native and invasive freshwater mussels, respectively. We anticipate that by 2050, the area suitable for palm oil cultivation may expand between 8 and 44â¯Mha, representing an annual increase of 2-11%. This is expected to result in a 20% decrease in suitable habitat for native mussels, a drop that reaches 30% by 2050 when considering concomitant climate change. In contrast, the habitat potentially suitable for invasive mussels may increase by 44-56% under 2050 future scenarios. Consequently, native mussels may compete for habitat, food resources and fish hosts with invasive mussels across approximately 60% of their suitable range. Our projections can be used to guide future expeditions to monitor the conservation status of freshwater biodiversity, and potentially reveal populations of endemic species on the brink of extinction. Future conservation measures-most importantly the designation of nature reserves-should take into account trends in freshwater biodiversity generally, and particularly species such as freshwater mussels, vital to safeguard fundamental ecosystem services.
Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales/métodos , Ecosistema , Agua Dulce , Animales , Cambio Climático , Monitoreo del AmbienteRESUMEN
The Spanish Bearded Vulture (Gypaetus barbatus) population has suffered from negative trends in a number of reproductive parameters that could jeopardize its long-term viability. From 1989 to 2012, 27 entire eggs and 63 eggshell fragments were collected from nests after breeding failure and/or fledging. Longer-term changes in eggshell thickness were made by examining 69 eggs collected in Spain from 1858 to 1911, and now held in European museums. Low levels of contamination with organochlorine pesticides and polychlorinated biphenyls were found in whole eggs and in conjunction with the high fertility rates observed in the field (66.7%) do not indicate a population suffering from the effects of organochlorine contamination. However, a decrease in the Ratcliffe Index and eggshell thickness were observed in eggs collected since 2001, increasingly so in samples post-2004, indicating an abrupt loss of egg quality. We found no significant relationship between organochlorine residues and eggshell in any of the variables measured. In contrast, we found a positive relationship between food availability and the Ratcliffe Index, eggshell thickness and eggshell surface area. A density-dependent explanation of reduced egg quality could arise from ecological constraints as the decrease of food resources. The impact of sudden changes in food availability due to sanitary regulations between 2006 and 2011 could be related with the loss of Bearded Vulture egg quality.
Asunto(s)
Cáscara de Huevo/ultraestructura , Falconiformes , Animales , Contaminantes Ambientales/análisis , Hidrocarburos Clorados/análisis , Óvulo , Bifenilos Policlorados/análisis , EspañaRESUMEN
Protected areas (PAs) are intended to provide native biodiversity and habitats with a refuge against the impacts of global change, particularly acting as natural filters against biological invasions. In practice, however, it is unknown how effective PAs will be in shielding native species from invasions under projected climate change. Here, we investigate the current and future potential distributions of 100 of the most invasive terrestrial, freshwater, and marine species in Europe. We use this information to evaluate the combined threat posed by climate change and invasions to existing PAs and the most susceptible species they shelter. We found that only a quarter of Europe's marine and terrestrial areas protected over the last 100 years have been colonized by any of the invaders investigated, despite offering climatically suitable conditions for invasion. In addition, hotspots of invasive species and the most susceptible native species to their establishment do not match at large continental scales. Furthermore, the predicted richness of invaders is 11%-18% significantly lower inside PAs than outside them. Invasive species are rare in long-established national parks and nature reserves, which are actively protected and often located in remote and pristine regions with very low human density. In contrast, the richness of invasive species is high in the more recently designated Natura 2000 sites, which are subject to high human accessibility. This situation may change in the future, since our models anticipate important shifts in species ranges toward the north and east of Europe at unprecedented rates of 14-55 km/decade, depending on taxonomic group and scenario. This may seriously compromise the conservation of biodiversity and ecosystem services. This study is the first comprehensive assessment of the resistance that PAs provide against biological invasions and climate change on a continental scale and illustrates their strategic value in safeguarding native biodiversity.
Asunto(s)
Cambio Climático , Conservación de los Recursos Naturales , Ecosistema , Especies Introducidas , Animales , Biodiversidad , Europa (Continente) , Actividades Humanas , Humanos , Modelos BiológicosRESUMEN
Churg-Strauss syndrome (CSS) is an unusual disease that presents as systemic vasculitis and peripheral eosinophilia in patients with an atopic constitution. Cardiac involvement is unusual and often not prominent on initial presentation, but is an important cause of morbidity and mortality in patients with CSS. We report the case of a young woman with severe acute myocarditis. Coronary arteriography demonstrated extensive focal vasculopathy, consistent with coronary vasculitis, and myocardial biopsy showed eosinophilic myocarditis. This presentation led to an initial diagnosis of CSS in this patient and appropriate therapy resulted in a spectacular remission of disease activity.
Asunto(s)
Síndrome de Churg-Strauss/complicaciones , Síndrome de Churg-Strauss/diagnóstico , Eosinofilia/etiología , Miocarditis/etiología , Femenino , Humanos , Adulto JovenRESUMEN
Pandemic 2009 H1N1 (pH1N1) influenza viruses caused mild symptoms in most infected patients. However, a greater rate of severe disease was observed in healthy young adults and children without co-morbid conditions. Here we tested whether influenza strains displaying differential virulence could be present among circulating pH1N1 viruses. The biological properties and the genotype of viruses isolated from a patient showing mild disease (M) or from a fatal case (F), both without known co-morbid conditions were compared in vitro and in vivo. The F virus presented faster growth kinetics and stronger induction of cytokines than M virus in human alveolar lung epithelial cells. In the murine model in vivo, the F virus showed a stronger morbidity and mortality than M virus. Remarkably, a higher proportion of mice presenting infectious virus in the hearts, was found in F virus-infected animals. Altogether, the data indicate that strains of pH1N1 virus with enhanced pathogenicity circulated during the 2009 pandemic. In addition, examination of chemokine receptor 5 (CCR5) genotype, recently reported as involved in severe influenza virus disease, revealed that the F virus-infected patient was homozygous for the deleted form of CCR5 receptor (CCR5Δ32).
Asunto(s)
Subtipo H1N1 del Virus de la Influenza A/fisiología , Gripe Humana/epidemiología , Gripe Humana/virología , Pandemias , Adulto , Alelos , Aminoácidos/genética , Animales , Línea Celular , Células Cultivadas , Citocinas/metabolismo , Células Epiteliales/patología , Células Epiteliales/virología , Femenino , Humanos , Inmunohistoquímica , Subtipo H1N1 del Virus de la Influenza A/genética , Gripe Humana/patología , Ratones , Ratones Endogámicos BALB C , Infecciones por Orthomyxoviridae/patología , Infecciones por Orthomyxoviridae/virología , Alveolos Pulmonares/patología , Alveolos Pulmonares/virología , Receptores CCR5/genética , Carga Viral , Replicación ViralRESUMEN
For more than 50 y ecologists have believed that spatial heterogeneity in habitat conditions promotes species richness by increasing opportunities for niche partitioning. However, a recent stochastic model combining the main elements of niche theory and island biogeography theory suggests that environmental heterogeneity has a general unimodal rather than a positive effect on species richness. This result was explained by an inherent tradeoff between environmental heterogeneity and the amount of suitable area available for individual species: for a given area, as heterogeneity increases, the amount of effective area available for individual species decreases, thereby reducing population sizes and increasing the likelihood of stochastic extinctions. Here we provide a comprehensive evaluation of this hypothesis. First we analyze an extensive database of breeding bird distribution in Catalonia and show that patterns of species richness, species abundance, and extinction rates are consistent with the predictions of the area-heterogeneity tradeoff and its proposed mechanisms. We then perform a metaanalysis of heterogeneity-diversity relationships in 54 published datasets and show that empirical data better fit the unimodal pattern predicted by the area-heterogeneity tradeoff than the positive pattern predicted by classic niche theory. Simulations in which species may have variable niche widths along a continuous environmental gradient are consistent with all empirical findings. The area-heterogeneity tradeoff brings a unique perspective to current theories of species diversity and has important implications for biodiversity conservation.
Asunto(s)
Biodiversidad , Ecología , Conservación de los Recursos Naturales , Funciones de Verosimilitud , Procesos EstocásticosRESUMEN
It is predicted that climate change will drive extinctions of some reptiles and that the number of these extinctions will depend on whether reptiles are able to change their distribution. Whether the latitudinal distribution of reptiles may change in response to increases in temperature is unknown. We used data on reptile distributions collected during the 20th century to analyze whether changes in the distributions of reptiles in Spain are associated with increases in temperature. We controlled for biases in sampling effort and found a mean, statistically significant, northward shift of the northern extent of reptile distributions of about 15.2 km from 1940-1975 to 1991-2005. The southern extent of the distributions did not change significantly. Thus, our results suggest that the latitudinal distributions of reptiles may be changing in response to climate change.
Asunto(s)
Cambio Climático , Reptiles/fisiología , Animales , Modelos Teóricos , Reptiles/clasificación , EspañaRESUMEN
Filoviruses, amongst the most lethal of primate pathogens, have only been reported as natural infections in sub-Saharan Africa and the Philippines. Infections of bats with the ebolaviruses and marburgviruses do not appear to be associated with disease. Here we report identification in dead insectivorous bats of a genetically distinct filovirus, provisionally named Lloviu virus, after the site of detection, Cueva del Lloviu, in Spain.
Asunto(s)
Quirópteros/virología , Reservorios de Enfermedades , Ebolavirus/aislamiento & purificación , Fiebre Hemorrágica Ebola/veterinaria , Animales , Secuencia de Bases , ADN Viral/análisis , Brotes de Enfermedades , Ebolavirus/genética , Genoma , Fiebre Hemorrágica Ebola/patología , Fiebre Hemorrágica Ebola/virología , Pulmón/patología , Pulmón/virología , Datos de Secuencia Molecular , Filogenia , España , Bazo/patología , Bazo/virologíaRESUMEN
Increased trimming and consequent carcass downgrade was experienced in a broiler flock. Condemned birds had gray to black pigmentation of the subcutaneous tissue and fat of the abdomen, and bluish pigmentation of the shanks. Histopathology revealed accumulation of melanin in these tissues. No significant bacteria were isolated. Accumulation of melanin in the skin and fascia is because of the cumulative and interactive effects of several genes. Additionally, pigmentation of abdominal fat has a high correlation with accumulation of melanin in the skin of the shanks. Although melanization of the skin and abdominal fascia is not harmful to people, it may cause severe economic losses to the producer.
Asunto(s)
Pollos , Melanosis/veterinaria , Enfermedades de las Aves de Corral/diagnóstico , Tejido Adiposo/patología , Animales , Femenino , Miembro Posterior , Masculino , Melanosis/genética , Melanosis/patología , Enfermedades de las Aves de Corral/genética , Enfermedades de las Aves de Corral/patología , Piel/patologíaRESUMEN
Aluminium (Al) has been recognised as a cause of bone tissue disorders. The aims of this work were to investigate: (i) whether Al affects calcium (Ca) entry into enterocyte, and (ii) the possibility that the Al effect upon calbindin-D-related Ca transport would be influenced by intestinal glutathione (GSH) levels. In isolated chicken duodenal enterocytes, 100 microM Al lactate produced a decrease in both, the maximum uptake rate and the affinity constant of 45Ca uptake (CaUPT). This effect of Al on CaUPT was concentration-dependent in the micromolar range, showing an inhibitory saturation type phenomenon which appeared to be higher at pH 6.5 than at pH 7.4, and was not modified by the Ca channel activators A23187 and capsaicin. The simultaneous administration of Al (50 mg elemental Al/kg body weight, as AlCl3) and GSH (10 mmol/kg body weight) to rats during 7 days, prevented the inhibitory effects of Al on Ca transport. The protective effect of GSH was accompanied by an increased duodenal calbindin-D9k expression. Experimental depletion of intestinal GSH by means of D,L-buthionin-[S,R] sulfoximine, a gamma-glutamylcystein-synthase inhibitor, given as a single i.p. dose of 2 mmol/kg body weight, enhanced the degree of reduction of Ca absorption ascribed to Al. Our results suggest that Al might interfere Ca uptake by enterocytes through a general effect on cell membrane, and that an oxidative stress state induced by Al would reduce intestine GSH level affecting calbindin-D function and/or synthesis, thus leading to a reduced transcellular Ca absorption in the small intestine.
Asunto(s)
Aluminio/farmacología , Calcio/metabolismo , Glutatión/metabolismo , Absorción Intestinal/efectos de los fármacos , Intestino Delgado/efectos de los fármacos , Animales , Agonistas de los Canales de Calcio/farmacología , Pollos , Intestino Delgado/metabolismo , Masculino , Ratas , Ratas WistarRESUMEN
To study the effects of aluminium (Al) on glutathione (GSH) metabolism in the small intestine, adult male Wistar rats were orally treated with AlCl3.6H2O at doses of 30, 60, 120 and 200 mg/kg body weight (b.w.) per day, during seven days. Controls received deionized water. At doses above 120 mg/kg b.w., Al produced both a significant reduction of GSH content and an increase of oxidized/reduced glutathione ratio (P < 0.05). The index of oxidative stress of the intestine mucosa in terms of lipid peroxidation evaluated by thiobarbituric acid reactive substances was significantly increased (52%) at higher Al dose used. The duodenal expression of the multidrug resistance-associated protein 2 in brush border membranes, determined by Western blot technique, was increased 2.7-fold in rats treated with 200mg AlCl3/kg b.w (P < 0.01). Intestine activities of both GSH-synthase (from 60 mg/kg b.w.) and GSSG-reductase (from 120 mg/kg b.w.) were significantly reduced (26% and 31%, respectively) while glutathione-S-transferase showed to be slightly modified in the Al-treated groups. Conversely, gamma-glutamyltranspeptidase activity was significantly increased (P < 0.05) due to the Al treatment. Al reduced in vitro mucosa-to-lumen GSH efflux (P < 0.05). A positive linear correlation between the intestine GSH depletion and reduction of in situ 45Ca intestinal absorption, both produced by Al, was found (r = 0.923, P = 0.038). Taking as a whole, these results show that Al would alter GSH metabolism in small intestine by decreasing its turnover, leading to an unbalance of redox state in the epithelial cells, thus contributing to deteriorate GSH-dependent absorptive functions.
Asunto(s)
Aluminio/toxicidad , Glutatión/metabolismo , Intestinos/efectos de los fármacos , Administración Oral , Animales , Glutatión Sintasa/metabolismo , Glutatión Transferasa/metabolismo , Mucosa Intestinal/metabolismo , Intestinos/enzimología , Peroxidación de Lípido , Masculino , Proteínas Mitocondriales/metabolismo , Ratas , Ratas Wistar , Proteínas Ribosómicas/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Sustancias Reactivas al Ácido Tiobarbitúrico/metabolismoRESUMEN
Ulcerative enteritis is found in a wide range of avian hosts but has not been described in psittacine birds. This case report describes ulcerative enteritis in four lories (two Trichoglossus sp. and two Eos sp.) that were found dead without any previous sign of disease. Macroscopically, all four birds showed good body condition. The only remarkable finding was a moderate dilatation of the small intestine with the presence of multiple yellow foci. Histologically, multiple ulcers extended into the submucosa and were filled with necrotic debris; bacteria and fibrin were observed in the intestinal mucosa. The liver and spleen exhibited a multifocal fibrinoid necrosis associated with a very moderate inflammatory reaction. Microbiological isolation revealed colonies of Clostridium colinum and Clostridium perfringens in the intestinal tract of the investigated birds.
Asunto(s)
Enfermedades de las Aves/microbiología , Infecciones por Clostridium/veterinaria , Enteritis/veterinaria , Animales , Enfermedades de las Aves/patología , Clostridium/aislamiento & purificación , Infecciones por Clostridium/microbiología , Infecciones por Clostridium/patología , Clostridium perfringens/aislamiento & purificación , Enteritis/microbiología , Enteritis/patología , Masculino , Loros , PsittaciformesRESUMEN
A case of neurological disease featuring human T lymphocyte virus-associated myelopathy/tropical spastic paraparesis (HAM/TSP) was diagnosed by serological (Western blot) and molecular (polymerase chain reaction) criteria as related to human T lymphocyte virus (HTLV)-II infection. This is, to our knowledge, the first case of this kind found in Argentina and is additional evidence that HAM/TSP solely related to HTLV-II infection occurs in HTLV-I-negative subjects.
Asunto(s)
Infecciones por HTLV-II/complicaciones , Virus Linfotrópico T Tipo 2 Humano , Paraparesia Espástica Tropical/complicaciones , Adulto , Argentina , Femenino , Humanos , Paraparesia Espástica Tropical/virologíaRESUMEN
Compared with other regions in Argentina, greater human T-cell lymphotropic virus type I (HTLV-I) seroprevalence has been reported in Jujuy Province, where it reaches 2.32% in the general population, so that a search for HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP) cases deserved to be carried out. Accordingly, a clinically diagnosed and serologically confirmed cluster of cases in 1 man and 10 women, including 2 sisters, is described here. Most patients (9/11) were born in Cochinoca Department, located in an Andes highland area called Puna Jujeña, situated at more that 3400 m above sea level. No history of risk factors was disclosed, except for a single transfusion in 1 patient. In contrast to the Andean region of Bolivia, where high HTLV-I seroprevalence is in part attributable to Japanese immigrants, the Jujuy population mainly consists of aborigines, mestizos, and European descendants. Therefore, the long-term presence of virus in Jujuy natives may be taken for granted. Considering the HAM/TSP cluster described here plus previously reported isolated cases in neighboring Salta Province, we speculate that the Puna Jujeña region and regions in that vicinity would be a microepidemic focus of disease. To determine the role of possible pathogenic cofactors such as geographic, ethnic, genetic, and cultural features, further pertinent surveys are required in subtropical northwestern Argentina.