Evaluating host-parasite co-adaptation relationships involving Angiostrongylus costaricensis.

Angiostrongylus costaricensis is a parasite that infects rodents, including the wild cotton rat Sigmodon hispidus and pygmy rice rats Oligoryzomys spp., among others. However, urban Rattus norvegicus and Mus musculus have not been identified as important hosts of A. costaricensis. In this study, Swiss mice (SW), Wistar R. norvegicus (RN), wild Oligoryzomys nigripes (ON) and a local strain of M. musculus (RGS) were experimentally infected with A. costaricensis. Survival, elimination of L1 (total sum per group, A0), and the number of adult worms recovered divided by the dose of each L3 inoculum (yield ratio, YR) were examined for each group after a 40-day post-infection period. The survival rates, A0 and YR values were: 27%, 207,589 and 0.42 for the SW group; 81%, 8691 and 0.01 for the RN group; and 63.6%, 26,560 and 0.16 for the RGS group, respectively, in each case. The survival rate for the ON group was 100% and the A0 value was 847,050. A YR was not calculated for the ON group since the ON group was maintained up to 565 days post-infection (pi) to examine long-term mortality. At 500 days pi (16 months), 50% of the ON group had died, while one animal (10%) survived 595 days pi (20 months). Taken together, these data indicate that A. costaricensis has undergone a greater degree of adaptation to the wild rodent, O. nigripes, than to R. norvegicus or a local M. musculus strain. In addition, titre curve (A0) modelling of adaptation status proved to be useful in evaluating A. costaricensis-rodent interactions.

[The using of hollow bricks as a shelter for adaptation of wild rodents' colonies in captivity]. / Tijolos vazados como abrigo para adaptação de roedores silvestres em cativeiro.

Difficulties for adaptation of wild rodents' colonies in the laboratory may hamper experimental studies. We describe the use of a hollow brick inside cages, to provide shelter and reduce stress of the animals. It facilitates the cleaning of cages, since the animals stay inside the brick while they are transferred to a new cage. This method was applied in a trial for adaptation of Oryzomys nigripes in captivity. Despite transportation for more than 1500 km, mortality was zero in the group of 62 rodents and the colony expanded immediately. A hollow brick is a cheap and widespread available material for improving adaptation of wild rodents to captivity.

Tijolos vazados como abrigo para adaptação de roedores silvestres em cativeiro / The using of hollow bricks as a shelter for adaptation of wild rodents' colonies in captivity

Difficulties for adaptation of wild rodents' colonies in the laboratory may hamper experimental studies. We describe the use of a hollow brick inside cages, to provide shelter and reduce stress of the animals. It facilitates the cleaning of cages, since the animals stay inside the brick while they are transferred to a new cage. This method was applied in a trial for adaptation of Oryzomys nigripes in captivity. Despite transportation for more than 1500 km, mortality was zero in the group of 62 rodents and the colony expanded immediately. A hollow brick is a cheap and widespread available material for improving adaptation of wild rodents to captivity.

Dificuldade para o estabelecimento de colônias de roedores silvestres no laboratório podem impedir realização de estudos experimentais. Descrevemos o emprego de tijolos vazados dentro das gaiolas, com objetivo de proporcionar abrigo e reduzir o estresse dos animais. Isto facilita a limpeza das gaiolas e outros procedimentos, já que os animais permanecem espontaneamente dentro do tijolo, enquanto são transferidos para uma nova gaiola. Este método foi empregado em uma tentativa de adaptação de Oryzomys nigripes em cativeiro. Apesar do transporte por mais de 1500km, mortalidade foi zero no grupo de 62 roedores e a colônia expandiu-se imediatamente. O tijolo vazado é um material barato, facilmente disponível e contribui para a adaptação de roedores silvestres em cativeiro.