Scurvy in capybaras bred in captivity in Argentine.

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.

The prevalence of Trypanosoma cruzi and the demography of dog populations after insecticidal spraying of houses: a predictive model.

A three-year demographic and seroparasitological follow-up of the canine population of a rural area of Argentina endemic for Chagas' disease was carried out in order to (a) describe the population dynamics of domestic dogs, and (b) predict the decrease in the prevalence of Trypanosoma cruzi among these reservoirs after indoor spraying of houses with residual insecticides. For the latter project we designed an age-structured model with a discrete time scale. We assumed a time-dependent exponential decay in the frequency of infected hosts proportional to the host mortality rate, and also assumed and that no differential mortality existed between infected and non-infected dogs. Validation of the model was carried out, and yielded an extremely close fit between observed and theoretical values. The relevance of the model as an aid to designing strategies for the control of animal domestic reservoirs of T. cruzi, and the role of dogs as efficient sentinels of re-infestation of an area, are discussed.

Propuestas para un control ecologico de la fiebre hemorragica Argentina a traves del manejo del habitat. / Proposals for an ecological control of Argentinian hemorrhagic fever by the management of the habitat

En este trabajo se analizo la variacion de las densidades de especies de roedores segun el tipo de cultivo y manejo agricola.Comparando campos de maiz y soja, a termino, se observo que en los primeros la densidad es mayor que en los segundos, mientras que esta es aun menor en los campos de cultivo invernal, excepto durante su rastrojo. Los campos de maiz que fueron pastoreados previamente a su siembra muestran, a termino menor densidad de roedores que los que no fueron pastoreados, mientras que en los campos de soja la siembra con maquina de trigo tiene un efecto similar. El efecto de los distintos cultivos y manejos varia segun la especie de roedor considerada, siendo las del genero Calomys las que muestran mayor variacion. Debido a que dichas especies son las de mayor importancia epidemiologica, se sugiere, como una primera aproximacion al control ecologico de la FHA, la siembra de soja en lugar de maiz en el area endemica y zonas aledanas, asi como el pastoreo intensivo de los campos previamente a la siembra

Propuestas para un control ecologico de la fiebre hemorragica Argentina a traves del manejo del habitat. / Proposals for an ecological control of Argentinian hemorrhagic fever by the management of the habitat

En este trabajo se analizo la variacion de las densidades de especies de roedores segun el tipo de cultivo y manejo agricola.Comparando campos de maiz y soja, a termino, se observo que en los primeros la densidad es mayor que en los segundos, mientras que esta es aun menor en los campos de cultivo invernal, excepto durante su rastrojo. Los campos de maiz que fueron pastoreados previamente a su siembra muestran, a termino menor densidad de roedores que los que no fueron pastoreados, mientras que en los campos de soja la siembra con maquina de trigo tiene un efecto similar. El efecto de los distintos cultivos y manejos varia segun la especie de roedor considerada, siendo las del genero Calomys las que muestran mayor variacion. Debido a que dichas especies son las de mayor importancia epidemiologica, se sugiere, como una primera aproximacion al control ecologico de la FHA, la siembra de soja en lugar de maiz en el area endemica y zonas aledanas, asi como el pastoreo intensivo de los campos previamente a la siembra

[Natural infection of Calomys musculinus (Rodentia, Cricetidae) by Trypanosoma cruzi]. / Infección natural de Calomys musculinus (Rodentia, Cricetidae) por Tripanosoma cruzi.

In the rural area of Las Higueras, Río Cuarto, Córdoba, Argentina, a trypanosoma was isolated from a wild rodent (C. musculinus). The trypanosome was classified as Trypanosoma cruzi because of the following characteristics: morphology as described by Hoare for the Schizotrypanum sub-genus: thin shaped, pointed back end, nucleus placed approximately in the middle of the body, prominent and subterminal kinetoplast and short free flagellum. The size measurements were as follows: total lengh 22.02 +/- 0.40 micron, flagellum lengh 5.93 +/- 0.29 mu, Nuclear mean index (NP/NA) 1,21 +/- 0.07 (Table 1). For some authors, this last value is very important for diagnosis of the parasite. BALB/c albino mice were infected with blood of the captured animal; those mice showed a mild parasitemia and amastigotes nests in cardiac fiber (Fig 2 a y b). The xenodiagnosis performed with nimphs of Triatoma infestans on the laboratory mice was positive. The trypanosome grew very well in blood-agar medium. According with these findings along with the wide geographic distribution and density of C. musculinus in Argentina, one should wonder whether or not this rodent is infested withT. cruzi on its whole distribution range. Passages through T. infestans and laboratory mice produced a virulence enhancement of this strain. With these findings, the question is if this situation should take place in nature, affecting domestic animals in any way. The stated questions and findings should estimulate further research on the role of the wild fauna in the epidemiclogy of Chagas' disease in Argintina.

Infección natural de Calomys musculinus (Rodentia, Cricetidae) por Tripanosoma cruzi / [Natural infection of Calomys musculinus (Rodentia, Cricetidae) by Trypanosoma cruzi]

In the rural area of Las Higueras, Río Cuarto, Córdoba, Argentina, a trypanosoma was isolated from a wild rodent (C. musculinus). The trypanosome was classified as Trypanosoma cruzi because of the following characteristics: morphology as described by Hoare for the Schizotrypanum sub-genus: thin shaped, pointed back end, nucleus placed approximately in the middle of the body, prominent and subterminal kinetoplast and short free flagellum. The size measurements were as follows: total lengh 22.02 +/- 0.40 micron, flagellum lengh 5.93 +/- 0.29 mu, Nuclear mean index (NP/NA) 1,21 +/- 0.07 (Table 1). For some authors, this last value is very important for diagnosis of the parasite. BALB/c albino mice were infected with blood of the captured animal; those mice showed a mild parasitemia and amastigotes nests in cardiac fiber (Fig 2 a y b). The xenodiagnosis performed with nimphs of Triatoma infestans on the laboratory mice was positive. The trypanosome grew very well in blood-agar medium. According with these findings along with the wide geographic distribution and density of C. musculinus in Argentina, one should wonder whether or not this rodent is infested withT. cruzi on its whole distribution range. Passages through T. infestans and laboratory mice produced a virulence enhancement of this strain. With these findings, the question is if this situation should take place in nature, affecting domestic animals in any way. The stated questions and findings should estimulate further research on the role of the wild fauna in the epidemiclogy of Chagas’ disease in Argintina.

Infección natural de Calomys musculinus (Rodentia, Cricetidae) por Tripanosoma cruzi. / [Natural infection of Calomys musculinus (Rodentia, Cricetidae) by Trypanosoma cruzi]

In the rural area of Las Higueras, Río Cuarto, Córdoba, Argentina, a trypanosoma was isolated from a wild rodent (C. musculinus). The trypanosome was classified as Trypanosoma cruzi because of the following characteristics: morphology as described by Hoare for the Schizotrypanum sub-genus: thin shaped, pointed back end, nucleus placed approximately in the middle of the body, prominent and subterminal kinetoplast and short free flagellum. The size measurements were as follows: total lengh 22.02 +/- 0.40 micron, flagellum lengh 5.93 +/- 0.29 mu, Nuclear mean index (NP/NA) 1,21 +/- 0.07 (Table 1). For some authors, this last value is very important for diagnosis of the parasite. BALB/c albino mice were infected with blood of the captured animal; those mice showed a mild parasitemia and amastigotes nests in cardiac fiber (Fig 2 a y b). The xenodiagnosis performed with nimphs of Triatoma infestans on the laboratory mice was positive. The trypanosome grew very well in blood-agar medium. According with these findings along with the wide geographic distribution and density of C. musculinus in Argentina, one should wonder whether or not this rodent is infested withT. cruzi on its whole distribution range. Passages through T. infestans and laboratory mice produced a virulence enhancement of this strain. With these findings, the question is if this situation should take place in nature, affecting domestic animals in any way. The stated questions and findings should estimulate further research on the role of the wild fauna in the epidemiclogy of Chagas disease in Argintina.