American tripanosomiasis: a study on the prevalence of Trypanosoma cruzi and Trypanosoma cruzi-like organisms in wild rodents in San Luis province, Argentina

INTRODUCTION: Chagas disease is caused by Trypanosoma cruzi. Wild and perianthropic mammals maintain the infection/transmission cycle, both in their natural habitat and in the peridomestic area. The aim of this paper was to present the results from a study on wild rodents in the central and northern regions of San Luis province, Argentina, in order to evaluate the prevalence of this infection. METHODS: Sherman traps were set up in capture areas located between latitudes 32º and 33º S, and longitudes 65º and 66º W. The captured rodents were taxonomically identified and hemoflagellates were isolated. Morphological, biometric and molecular studies and in vitro cultures were performed. Infection of laboratory animals and histological examination of the cardiac muscle and inoculation area were also carried out. Parasites were detected in circulating blood in Calomys musculinus, Graomys griseoflavus, Phyllotis darwini and Akodon molinae. The parasites were identified using biological criteria. Molecular PCR studies were performed on some isolates, which confirmed the characterization of these hemoflagellates as Trypanosoma cruzi. RESULTS AND CONCLUSIONS: Forty-four percent of the 25 isolates were identified as Trypanosoma cruzi, and the remaining 56% as Trypanosoma cruzi-like. These findings provide evidence that wild rats infected with Trypanosoma cruzi and Trypanosoma cruzi-like organisms are important in areas of low endemicity.

Diagnosis of hantavirus infection in humans and rodents in Ribeirão Preto, State of São Paulo, Brazil

INTRODUCTION: Hantavirus pulmonary and cardiovascular syndrome (HPCS) is an emerging serious disease in the Americas. Hantaviruses (Bunyaviridae) are the causative agents of this syndrome and are mainly transmitted through inhalation of aerosols containing the excreta of wild rodents. In the Ribeirão Preto region (state of São Paulo, Brazil), HPCS has been reported since 1998, caused by the Araraquara virus (ARAV), for which Necromys lasiurus is the rodent reservoir. This study aimed to show diagnostic results relating to infection in humans and rodents, obtained at the Virology Research Center of the Ribeirão Preto School of Medicine, University of São Paulo, between 2005 and 2008. METHODS: HPCS was diagnosed by means of ELISA and/or RT-PCR in 11 (21.2%) out of 52 suspected cases, and 54.4% of these were fatal. Furthermore, 595 wild rodents (Necromys lasiurus, Akodon sp, Calomys tener and Oligoryzomys sp) were caught between 2005 and 2008. RESULTS: Fifteen (2.5%) of these rodents presented antibodies for hantavirus, as follows: Necromys lasiurus (4%), Calomys tener (1.9%) and Akodon sp (1.5%). Nucleotide sequences obtained through RT-PCR from one HPCS patient and one Calomys tener rodent were compared with hantavirus sequences from GenBank, which showed that both were homologous with ARAV. CONCLUSIONS: This work corroborates previous studies showing that ARAV is the hantavirus causing HPCS in the Ribeirão Preto region. It also shows that rodents infected with hantavirus represent a constant risk of transmission of this virus to man.

The parasitism of Ixodes luciae (Acari: Ixodidae) on marsupials and rodents in Peruvian Amazon

In this work the infestation with I. luciae on Didelphimorphia and Rodentia in different environments of Peruvian Amazon was studied. Didelphimorphia was represented by the family Didelphidae. Specimens belonging to Caluromys lanatus, Didelphis marsupialis, Marmosops sp.2, Metachirus nudicaudatus, Philander andersoni and Philander opossum were infested with adults I. luciae and one Micoureus sp. was infested with larvae. In Rodentia, the infestation with I. luciae nymphs was restricted to Hylaeamys perenensis, Hylaeamys yunganus and Oligoryzomys microtis, while one Oecomys bicolor (all Cricetidae) was infested with larvae of this species. The few larvae were found on rodents captured in primary forest. The only significant difference (P < 0.05) in prevalence of adult ticks on Didelphimorphia was between P. andersoni and M. nudicaudatus (chi-square distribution). Adult tick distribution was significant different in P. andersoni in comparison with M. nudicaudatus, P. opossum and D. marsupialis (Kruskal-Wallis test). No significant effect of month or environment was detected in relation to adult tick infestation on Didelphimorphia. The prevalence of nymphal infestation as well as tick distribution showed that H. perenensis and H. yunganus were significantly more prone to be infested with nymphs of I. luciae than O. microtis. Prevalence of nymph infestation was higher in primary and secondary forest than rural areas while abundance was higher in secondary forest when compared with rural areas (P < 0.05). Kruskal-Wallis test showed differences (P < 0.05) for nymphal infestation during December in relation to January, March, April and June. The natural cycle of I. luciae appeared to be continuous, bound to adult tick infestation on Philander and nymphal infestation on Hylaeamys in forested environs.

“PhenoWorld”: a new multidimensional strategy for studying behaviour in rodents

Tese de Doutoramento em Ciências da Saúde

List of species of mammals, principally rodents, obtained by W. W. Price, S. E. Meek, G. K. Cherrie and E. S. Thompson, in the States of Iowa, Wyoming, Montana, Idaho, Nevada and California, with descriptions of new species, by D. E. Elliot.

v.1:no.10(1898)

Preliminary descriptions of new rodents from the Olympic Mountains.

v.1:no.11(1899)

The long-clawed South American rodents of the genus Notiomys, by Wilfred H. Osgood. Report on results of the Captain Marshall Field expeditions.

v.12:no.9(1925)

Evolution of neotropical cricetine rodents (Muridae) with special reference to the phyllotine group.

v.46(1962)

South American marsh rats, Genus Holochilus, with a summary of sigmodont rodents.

v.37:no.24(1955)

Nine new South American rodents, by Wilfred H. Osgood.

v.29:no.13(1944)

Two new rodents from Argentina, by Wilfred H. Osgood.

v.20:no.3(1933)

Two new rodents from Costa Rica, by Wilfred H. Osgood.

v.18:no.5(1931)

A new genus of aquatic rodents from Abyssinia, by Wilfred H. Osgood.

v.12:no.15(1928)

The Mylagaulidæ; an extinct family of sciuromorph rodents / by Elmer S. Riggs, A.M., Asst. Curator, Dept. of Geology ; Oliver Cummings Farrington, Ph.D., Curator, Dept. of Geology.

v.1:no.4(1899)

Pneumocystis carinii: its incidence in rodents and enhancement of the infection by corticosteroids

A survey was made on the incidence of Pneumocystis carinii in 361 rodents including sewer rats, albino rats, albino mice, guinea-pigs and rabbits. P. carinii was found in 4 of the 215 Rattus norvegicus examined (1,8%). These results accord with recent observations but disagree with investigations made by the researchers who first studied this parasite in the past when high indexes of infection were found. However, in 20 albino rats treated with corticosteroids (betamethazone) we found 8 positive (40%) and in 20 albino mice treated by the same way, 9 were positive for P. carinii (45%). These results confirm the opportunistic character of P. carinii in rodents already well demonstrated in man.