Occurrence of potential wild hosts of Echinococcus vogeli in the forests of southwestern Brazilian Amazonia / Ocorrência de potenciais hospedeiros silvestres de Echinococcus vogeli nas florestas do sudoeste da Amazônia brasileira

Abstract The helminth Echinococcus vogeliRausch & Bernstein, 1972 is a causative agent of Neotropical Echinococcosis, a chronic zoonotic disease which is endemic to the Neotropical region. This parasite is transmitted from bush dogs (Speothos venaticus) to their prey, which include lowland pacas (Cuniculus paca) and agoutis (Dasyprocta spp.). In Brazil, most human cases of Neotropical Echinococcosis have been recorded in the Amazonian states of Acre and Pará, although few data are available on the occurrence of the potential definitive or intermediate hosts of E. vogeli in the Amazon region. In the present study, we surveyed the forests surrounding 46 human communities located within and around of outside six sustainable-use protected areas in the southwestern Amazon basin of Brazil. The forests were surveyed using camera traps to determine the local presence of potential wild hosts of E. vogeli, and the exploitation of these hosts for game meat was evaluated through interviews with 136 subsistence hunters resident in the local communities. We recorded pacas, agoutis, and bush dogs, as well as domestic dogs (Canis familiaris), all potential reservoirs of Neotropical Echinococcosis, using the same habitats. We also confirmed the frequent consumption of paca and agouti meat by subsistence hunters and their families in the study communities. Our data contribute to the understanding of the occurrence of E. vogeli in Brazilian ecosystems.

Resumo O helminto Echinococcus vogeliRausch & Bernstein, 1972 é o agente causador da Equinococose Neotropical, uma doença zoonótica crônica e endêmica da região Neotropical. Este parasito é transmitido entre o cachorro-vinagre (Speothos venaticus) e suas presas, como pacas (Cuniculus paca) e cutias (Dasyprocta spp.). No Brasil, a maioria dos casos humanos de Equinococose Neotropical é registrada nos estados do Acre e Pará, embora existam poucos dados disponíveis sobre a ocorrência de potenciais hospedeiros definitivos e intermediários de E. vogeli na Amazônia. No presente estudo, foram investigadas áreas de floresta ao redor de 46 comunidades humanas localizadas no interior e entorno de seis unidades de conservação de uso sustentável no sudoeste da bacia amazônica brasileira e, por meio de armadilhas fotográficas, foram avaliadas as presenças de potenciais hospedeiros silvestres de E. vogeli. Adicionalmente, foram avaliados o padrão de consumo da carne dos hospedeiros silvestres por meio de entrevistas com 136 moradores dessas comunidades. Foram registradas pacas, cutias e cachorros-vinagre, bem como cães domésticos (Canis familiaris) utilizando os mesmos habitats, todos potenciais reservatórios da Equinococose Neotropical. Além disto, confirmamos a alto consumo de paca e cutia nas comunidades. Os dados do presente trabalho contribuem para pesquisas em andamento sobre a presença dos potenciais reservatórios de E. vogeli em ambientes brasileiros.

Spurious infection by Calodium hepaticum (Bancroft, 1983) Moravec, 1982 and intestinal parasites in forest reserve dwellers in Western Brazilian Amazon

ABSTRACT Subsistence hunting is the main source of protein for forest reserve dwellers, contributing to the development of spurious infections by Calodium hepaticum, frequently associated with the consumption of the liver from wild mammals. The prevalence of infections by soil-transmitted helminths (STHs) and intestinal protozoa is considered an indicator of the social vulnerability of a country, besides providing information on habits, customs and quality of life of a given population. Intestinal parasites mostly affect poor rural communities with limited access to clean water and adequate sanitation. This study reports the results of a parasitological survey carried out in 2017 and 2019, in two municipalities (Xapuri and Sena Madureira) in Acre State. Stool samples were collected from 276 inhabitants. Upon receipt, each sample was divided into two aliquots. Fresh samples without preservative were processed and examined by the Kato-Katz technique. Samples fixed in 10% formalin were processed by the spontaneous sedimentation and the centrifugal sedimentation techniques. Calodium hepaticum eggs were found in three stool samples. The overall STH prevalence was 44.9%. The hookworm prevalence (19.2%) was higher than that of Ascaris lumbricoides (2.5%) and Trichuris trichiura (0.7%), an unexpected finding for municipalities belonging to the Western Brazilian Amazon. When considering parasites transmitted via the fecal-oral route, Endolimax nana and Entamoeba coli showed the highest positivity rates, of 13% and 10.9%, respectively. This study is the first report of spurious infection by C. hepaticum among forest reserve dwellers that consume undercooked liver of lowland pacas. Additionally, this is the first report of Blastocystis sp. in Acre State.

Evaluation of the resistance to Schistosoma mansoni infection in nectomys squamipes rodentia: cricetidae a natural host of infection in Brazil

O desenvolvimento de resistencia em tres fases do transcurso de uma infeccao ativa (fase pre-ovular, aguda e cronica inicial) foi estudada comparando-se o numero total de vermes adultos recuperados no grupo reinfectado e o somatorio dos grupos controles. Demonstrou-se que o N. squamipes nao foi capaz de desenvolver resisitencia nas condicoes testadas e que ao contrario, a reinfeccao no periodo pre-ovular do parasito levou o roedor a apresentar o fenomeno de facilitacao, com reducao da resistencia natural e aumento da carga parasitaria. Esses resultados sugerem a existencia de outras formas de imunidade, distintas da imunidade concomitante, segundo o modelo empregado.

Natural infection of wild rodents by Schistosoma mansoni parasitological aspects

The evaluation of the role of rodents as natural hosts of Schistosoma mansoni was studied at the Pamparräo Valley, Sumidouro, RJ, with monthly captures and examination of the animals. Twenty-three Nectomys squamipes and 9 Akodom arviculoides with a shistosomal infection rate of 56.5% and 22.2% respectively eliminated a great majority of viable eggs. With a strain isolated from one of the naturally infected N. squamipes, we infected 75% of simpatric Biomphalaria glabrata and 100% of albino Mus musculus mice. The adult worms, isolated from N. squamipes after perfusion were located mainly in the liver (91.5%) and the mesenteric veins (8.5%). The male/female proportion was 2:1. The eggs were distributed on small intestine segments (proximal, medial and distal portions) and the large intestine without any significant differences in egg concentration of these segments. In A. arviculoides, the few eggs eliminated by the stools were viable and there was litlle egg retention on intestinal segments. Considering the ease to complete S. mansoni biological cycle in the Nectomys/Biomphalaria/Nectomys system under laboratory conditions, probably the same is likely to occur in natural conditions. In support to this hypotesis there are also the facts that human mansonic shistosomiasis has a very low prevalence in Sumidouro and endemicity among the rodents has not changed even after repetead treatments of the local patients. Based on our experiments, we conclude that N. squamipes has become a natural host of S. mansoni and possibly may participate in keeping the cycle of schistosomiasis transmission at Pamparräo Valley

Nectomys squamipes (Rodentia: Cricetidae) as an experimental model for schistosomiasis mansoni

Twenty specimens of Nectomys squamipes born in captivity, were infected with 500 cercariae by the transcutaneous route. Coprologic examinations were carried out from the 5th to 23rd week after infection. On the 7th, 8th, 12th, 16th, and 23rd weeks the animals were sacrificed and perfused. The oogram was performed in segments of the small intestine (proximal, medial and distal portions) and the large intestine. The average pre-patent period was of 42 days. The average number of eggs varied from 350 on 6th week, to 800 on the 13th. From the 14th week on, the average number of eggs eliminated was lower than 50 per gram of feces. The recovery of worms kept steady on the 7th, 8th, and 12th week (16.85%; 15.45% and 11.95%), decreasing to 7.70% on the 16th week and 8.45% on the 23rd week. The proportion of male/female worms was about the same on the first two weeks, but from the 12th week on, the proportion was: 1,4/1 on the 12th week; 2,5/1 on the 16thweek and 1,8/1 on the 23rd weekThese observations suggest that N. squamipes may used as an experimental model for schistosomiasis mansoni, to wich it develops resistance mechanism, useful for immunity studies