Maintenance and breeding of Thrichomys (Trouessart, 1880) (Rodentia: Echimyidae) in captivity

South American histricognath rodents Thrichomys apereoides laurentius and Thrichomys pachyurus are natural hosts of Trypanosoma cruzi, agent of Chagas disease. We established breeding colonies of these species to serve as experimental models in various parasitological studies. Both species of Thrichomys have all the requirements necessary to become excellent laboratory models: they can be easily maintained in the standard laboratory conditions and breed throughout the year and they do not have any special dietary demands and can be fed by standard food pellets designed for laboratory mice. Both species produce precocious offspring that have their eyes and ears open, teeth erupted, fur well developed, and can eat solid food in the first week of life. T. a. laurentius has larger litter sizes and lower body masses at birth and weaning than T. pachyurus. Moreover, females of T. a. laurentius reach puberty earlier and with lower body mass than T. pachyurus.

Detection of Mycobacterium tuberculosis in sputum from Suruí Indian subjects, Brazilian Amazon

This investigation aimed at the detection of Mycobacterium tuberculosis (MTB) in the sputum of Suruí Indian subjects from Amazonia, Brazil. Polymerase chain reaction analyses were positive for12 samples, five of which were also culture-positive (N = 147). Four MTB genotypes were identified, one of which showed resistance to rifampicin and isoniazid. The study also highlighted one village complex as of particular importance, considering the relatively high number of tuberculosis cases reported and of MTB isolates obtained.

Germline transformation of Aedes fluviatilis (Diptera:Culicidae) with the piggyBac transposable element

The technique to generate transgenic mosquitoes requires adaptation for each target species because of aspects related to species biology, sensitivity to manipulation and rearing conditions. Here we tested different parameters on the microinjection procedure in order to obtain a transgenic Neotropical mosquito species. By using a transposon-based strategy we were able to successfully transform Aedes fluviatilis (Lutz), which can be used as an avian malaria model. These results demonstrate the usefulness of the piggyBac transposable element as a transformation vector for Neotropical mosquito species and opens up new research frontiers for South American mosquito vectors.

Aedes aegypti, Aedes albopictus, and dengue in Argentina: current knowledge and future directions

Since the reinfestation of South American countries by Ae. aegypti, dengue fever (DF) and dengue hemorrhagic fever (DHF) have become a major public health concern. The aim of this paper was to review the information related with Aedes vectors and dengue in Argentina since the reintroduction of Ae. aegypti in 1986. The geographic distribution of Ae. albopictus is restricted to the Northeast, and that of Ae. aegypti has expanded towards the South and the West in comparison with the records during the eradication campaign in the 1960s. Since 1998, 4,718 DF cases have been reported concentrated in the provinces of Salta, Formosa, Misiones, Jujuy and Corrientes. Despite the circulation of three dengue virus serotypes (DENV-1, -2 and -3) in the North of the country, DHF has not occurred until the present. The information published over the last two decades regarding mosquito abundance, temporal variations, habitat characteristics, competition, and chemical and biological control, was reviewed. Considering the available information, issues pending in Argentina are discussed. The presence of three DENV, the potential spread of Ae. albopictus, and the predicted climate change suggest that dengue situation will get worse in the region. Research efforts should be increased in the Northern provinces, where DHF is currently an actual risk.

Experimental infection of dogs with a Brazilian strain of Rickettsia rickettsii: clinical and laboratory findings

The bacterium Rickettsia rickettsii is the etiological agent of an acute, severe disease called Rocky Mountain spotted fever in the United States or Brazilian spotted fever (BSF) in Brazil. In addition to these two countries, the disease has also been reported to affect humans in Mexico, Costa Rica, Panama, Colombia and Argentina. Like humans, dogs are also susceptible to R. rickettsii infection. However, despite the wide distribution of R. rickettsii in the Western Hemisphere, reports of R. rickettsii-induced illness in dogs has been restricted to the United States. The present study evaluated the pathogenicity for dogs of a South American strain of R. rickettsii. Three groups of dogs were evaluated: group 1 (G1) was inoculated ip with R. rickettsii; group 2 (G2) was infested by R. rickettsii-infected ticks; and the control group (G3) was infested by uninfected ticks. During the study, no clinical abnormalities, Rickettsia DNA or R. rickettsii-reactive antibodies were detected in G3. In contrast, all G1 and G2 dogs developed signs of rickettsial infection, i.e., fever, lethargy, anorexia, ocular lesions, thrombocytopenia, anemia and detectable levels of Rickettsia DNA and R. rickettsii-reactive antibodies in their blood. Rickettsemia started 3-8 days after inoculation or tick infestation and lasted for 3-13 days. Our results indicate that a Brazilian strain of R. rickettsii is pathogenic for dogs, suggesting that canine clinical illness due to R. rickettsii has been unreported in Brazil and possibly in the other South American countries where BSF has been reported among humans.

Dengue virus type 3 in Brazil: a phylogenetic perspective

Circulation of a new dengue virus (DENV)-3 genotype was recently described in Brazil and Colombia, but the precise classification of this genotype has been controversial. Here we perform phylogenetic and nucleotide-distance analyses of the envelope gene, which support the subdivision of DENV-3 strains into five distinct genotypes (GI to GV) and confirm the classification of the new South American genotype as GV. The extremely low genetic distances between Brazilian GV strains and the prototype Philippines/L11423 GV strain isolated in 1956 raise important questions regarding the origin of GV in South America.

Records of Chrysomya albiceps in Northern Italy: an ecological and forensic perspective

Knowledge of the carrion-breeding insects present at a local level is important and necessary for defining the post-mortem interval. Climate changes and globalisation are affecting species ranges and population dynamics. In this note, we report the incidence of Chrysomya albiceps (Diptera: Calliphoridae) on dead human bodies and carrion in Northern Italy. These data confirm the spread of this species in the Northern regions. The partial sequencing of a 583-bp region of the cytochrome oxidase subunit 1 gene of an Adriatic population did not reveal any difference compared to the same genomic region in the African and South American populations of this species.

Current epidemiological trends for Chagas disease in Latin America and future challenges in epidemiology, surveillance and health policy

Chagas disease, named after Carlos Chagas, who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, which is transmitted to humans by blood-sucking triatomine bugs and via blood transfusion. Chagas disease has two successive phases: acute and chronic. The acute phase lasts six-eight weeks. Several years after entering the chronic phase, 20-35% of infected individuals, depending on the geographical area, will develop irreversible lesions of the autonomous nervous system in the heart, oesophagus and colon, and of the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980s as a result of the demographically representative cross-sectional studies in countries where accurate information was not previously available. A group of experts met in Brasilia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country programme in the Southern Cone countries, the transmission of Chagas disease by vectors and via blood transfusion was interrupted in Uruguay in 1997, in Chile in 1999 and in Brazil in 2006; thus, the incidence of new infections by T. cruzi across the South American continent has decreased by 70%. Similar multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been reported towards the goal of interrupting the transmission of Chagas disease, as requested by a 1998 Resolution of the World Health Assembly. The cost-benefit analysis of investment in the vector control programme in Brazil indicates that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the programme is a health investment with very high return. Many well-known research institutions in Latin America were key elements of a worldwide network of laboratories that carried out basic and applied research supporting the planning and evaluation of national Chagas disease control programmes. The present article reviews the current epidemiological trends for Chagas disease in Latin America and the future challenges in terms of epidemiology, surveillance and health policy.

Phylogeny, ultrastructure, histopathology and prevalence of Myxobolus oliveirai sp. nov., a parasite of Brycon hilarii (Characidae) in the Pantanal wetland, Brazil

This paper presents the morphological, histological and ultrastructural characteristics of Myxobolus oliveirai sp. nov., a parasite of the gill filaments in Brycon hilarii from the Brazilian Pantanal. Out of 216 B. hilariispecimens examined (126 wild and 90 cultivated), 38.1% of wild specimens (n = 48) were infected. The parasites form elongated plasmodia primarily in the tip of gill filaments, reaching about 3 mm in length. A thorough comparison with all the Myxobolus species described from South American hosts, as well as nearly all the Myxobolus species described so far is provided. Partial sequencing of the 18S rDNA gene revealed a total of 1,527 bp. The Myxobolus species parasite of B. hilarii did not match any of the Myxozoa available in GenBank. In the phylogenetic analysis, M. oliveirai sp. nov. composed a monophyletic group with eight other species: five species of Myxobolus parasites of mugilid fishes, two parasites of pangasiid and one of centrarchid. Infection prevalence values of the parasite revealed no significant differences between wet and dry seasons or between males and females. The importance of the infection to the farming of the host species is emphasized.

Neutralising antibodies for West Nile virus in horses from Brazilian Pantanal

Despite evidence of West Nile virus (WNV) activity in Colombia, Venezuela and Argentina, this virus has not been reported in most South American countries. In February 2009, we commenced an investigation for WNV in mosquitoes, horses and caimans from the Pantanal, Central-West Brazil. The sera of 168 horses and 30 caimans were initially tested using a flaviviruses-specific epitope-blocking enzyme-linked immunosorbent assay (blocking ELISA) for the detection of flavivirus-reactive antibodies. The seropositive samples were further tested using a plaque-reduction neutralisation test (PRNT90) for WNV and its most closely-related flaviviruses that circulate in Brazil to confirm the detection of specific virus-neutralising antibodies. Of the 93 (55.4%) blocking ELISA-seropositive horse serum samples, five (3%) were seropositive for WNV, nine (5.4%) were seropositive for St. Louis encephalitis virus, 18 (10.7%) were seropositive for Ilheus virus, three (1.8%) were seropositive for Cacipacore virus and none were seropositive for Rocio virus using PRNT90, with a criteria of > four-fold antibody titre difference. All caimans were negative for flaviviruses-specific antibodies using the blocking ELISA. No virus genome was detected from caiman blood or mosquito samples. The present study is the first report of confirmed serological evidence of WNV activity in Brazil.

Molecular identification of Rickettsia parkeri infecting Amblyomma triste ticks in an area of Argentina where cases of rickettsiosis were diagnosed

Specimens of the hard tick Amblyomma triste were found infected with Rickettsia parkeri in an area of Argentina (General Lavalle, Buenos Aires Province) where cases of human illness attributed to this microorganism have been reported. Molecular detection of R. parkeri was based on polymerase chain reactions that amplify a ca. 400-bp fragment of the 23S-5S intergenic spacer and a ca. 500-bp fragment of the gene encoding a 190-kDa outer membrane protein. Three (6.97%) of 43 A. triste ticks were determined to be positive for R. parkeri. These results provide strong evidence that A. triste is the vector of R. parkeri in the study area. The findings of this work have epidemiological relevance because human parasitism by A. triste ticks has been frequently recorded in some riparian areas of Argentina and Uruguay and new cases of R. parkeri rickettsiosis might arise in the South American localities where humans are exposed to the bites of this tick species.

Ultrastructural description of Ceratomyxa microlepis sp. nov. (Phylum Myxozoa): a parasite infecting the gall bladder of Hemiodus microlepis, a freshwater teleost from the Amazon River

A new ceratomyxid parasite was examined for taxonomic identification, upon being found infecting the gall bladder of Hemiodus microlepis (Teleostei: Hemiodontidae), a freshwater teleost collected from the Amazon River, Brazil. Light and transmission electron microscopy revealed elongated crescent-shaped spores constituted by two asymmetrical shell valves united along a straight sutural line, each possessing a lateral projection. The spores body measured 5.2 ± 0.4 µm (n = 25) in length and 35.5 ± 0.9 µm (n = 25) in total thickness. The lateral projections were asymmetric, one measuring 18.1 ± 0.5 µm (n = 25) in thickness and the other measuring 17.5 ± 0.5 µm (n = 25) in thickness. Two equal-sized subspherical polar capsules measuring 2.2 ± 0.3 µm in diameter were located at the same level, each possessing a polar filament with 5-6 coils. The sporoplasm was binucleate. Considering the morphometric data analyzed from the microscopic observations, as well as the host species and its geographical location, this paper describes a new myxosporean species, herein named Ceratomyxa microlepis sp. nov.; therefore representing the first description of a freshwater ceratomyxid from the South American region.

Prevalence of antibody to hantaviruses in humans and rodents in the Caribbean region of Colombia determined using Araraquara and Maciel virus antigens

We tested sera from 286 agricultural workers and 322 rodents in the department of Córdoba, northeastern Colombia, for antibodies against two hantaviruses. The sera were analysed by indirect ELISA using the lysate of Vero E6 cells infected with Maciel virus (MACV) or the N protein of Araraquara virus (ARAV) as antigens for the detection of antibodies against hantaviruses. Twenty-four human sera were IgG positive using one or both antigens. We detected anti-MACV IgG antibodies in 10 sera (3.5%) and anti-ARAV antibodies in 21 sera (7.34%). Of the 10 samples that were positive for MACV, seven (70%) were cross-reactive with ARAV; seven of the 21 ARAV-positive samples were cross-reactive with MACV. Using an ARAV IgM ELISA, two of the 24 human sera (8.4%) were positive. We captured 322 rodents, including 210 Cricetidae (181 Zygodontomys brevicauda, 28 Oligoryzomys fulvescens and 1 Oecomys trinitatis), six Heteromys anomalus (Heteromyidae), one Proechimys sp. (Echimyidae) and 105 Muridae (34 Rattus rattus and 71 Mus musculus). All rodent sera were negative for both antigens. The 8.4% detection rate of hantavirus antibodies in humans is much higher than previously found in serosurveys in North America, suggesting that rural agricultural workers in northeastern Colombia are frequently exposed to hantaviruses. Our results also indicate that tests conducted with South American hantavirus antigens could have predictive value and could represent a useful alternative for the diagnosis of hantavirus infection in Colombia.

Serologic survey of West Nile virus in horses from Central-West, Northeast and Southeast Brazil

Since the emergence of West Nile virus (WNV) in North America in 1999, there have been several reports of WNV activity in Central and South American countries. To detect WNV in Brazil, we performed a serological survey of horses from different regions of Brazil using recombinant peptides from domain III of WNV. Positive samples were validated with the neutralisation test. Our results showed that of 79 ELISA-positive horses, nine expressed WNV-specific neutralising antibodies. Eight of the infected horses were from the state of Mato Grosso do Sul and one was from the state of Paraíba. Our results provide additional evidence for the emergence of WNV in Brazil and for its circulation in multiple regions of the country.

Aedes aegypti on Madeira Island (Portugal): genetic variation of a recently introduced dengue vector

The increasing population of Aedes aegypti mosquitoes on Madeira Island (Portugal) resulted in the first autochthonous dengue outbreak, which occurred in October 2012. Our study establishes the first genetic evaluation based on the mitochondrial DNA (mtDNA) genes [cytochrome oxidase subunit I (COI) and NADH dehydrogenase subunit 4 (ND4)] and knockdown resistance ( kdr ) mutations exploring the colonisation history and the genetic diversity of this insular vector population. We included mosquito populations from Brazil and Venezuela in the analysis as putative geographic sources. The Ae. aegypti population from Madeira showed extremely low mtDNA genetic variability, with a single haplotype for COI and ND4. We also detected the presence of two important kdr mutations and the quasi-fixation of one of these mutations (F1534C). These results are consistent with a unique recent founder event that occurred on the island of Ae. aegypti mosquitoes that carry kdr mutations associated with insecticide resistance. Finally, we also report the presence of the F1534C kdr mutation in the Brazil and Venezuela populations. To our knowledge, this is the first time this mutation has been found in South American Ae. aegypti mosquitoes. Given the present risk of Ae. aegypti re-invading continental Europe from Madeira and the recent dengue outbreaks on the island, this information is important to plan surveillance and control measures.