Hantaviroses

Hantavirus Infection and the Renal Syndrome

Fever with renal syndrome is currently endemic in Eurasia, where the main etiological agents are the Hantaan and Seoul viruses in Asia (China, South Korea, and the Far East of Russia), in addition to the Seoul, Puumala, and Dobrava viruses in Europe (central, northern, Alpine Massif, Balkans, and western Russia). Lethality rates are higher with Hantaan and Dobrava virus infections (5–10%) when compared to the Puumala and Seoul viruses (1%). With the expansion and geographical migration of the urban rodent (Rattus norvegicus) from the “Old World,” the Seoul virus was introduced into the Americas and is now considered a virus with a cosmopolitan distribution. On the American continent, the presence of the Seoul virus has been confirmed in Brazil, Argentina, and the United States. The hantavirus transmission to humans occurs by inhalation of aerosol-dispersed viral particles present in rodent droppings and saliva. This disease should be clinically differentiated from leptospirosis and other viral hemorrhagic fevers that occur in the same areas of occurrence of hantavirus infections. There is no treatment with antiviral drugs specific for hantavirus. Faced to a suspected hantavirus case, it should be communicated to the local health authorities and provide an eventually intensive care unit support.

Malaria and Hantavirus Pulmonary Syndrome in Gold Mining in the Amazon Region, Brazil

People living in mining regions are exposed to numerous biological agents by several specific types of transmission mechanisms. This study is designed to describe fatal hantavirus pulmonary syndrome (HPS) cases confirmed by serology and molecular analysis, where a seroprevalence survey was conducted in the gold mining regions of the state of Mato Grosso, in the official Amazon region, Brazil. Two fatal cases of HPS were confirmed in a mining area in the Legal Amazon, where malaria is one of the most important public health problems. A molecular analysis detected the presence of the genome of the Castelo dos Sonhos virus. Out of the 112 blood samples analyzed, five were positive for Plasmodium infection (four P. falciparum and one P. vivax), and four were seropositive for hantavirus, showing a seroprevalence of 3.57%. One of the four miners who was seroreactive for hantavirus concomitantly had P. falciparum infection, which was confirmed by thick blood smear. This manuscript highlights the importance of considering hantavirus pulmonary syndrome as a diagnostic possibility in febrile infection associated with pulmonary manifestations in mining areas where malaria cases are often identified.

Serologic survey of hantavirus in a rural population from the northern State of Mato Grosso, Brazil

INTRODUCTION

Hantavirus is a genus of ribonucleic acid (RNA) viruses included in the family Bunyaviridae. Hantaviruses are rodent-borne zoonoses that, in the last 18 years, became an emergent public health problem in the Americas, causing a severe cardiopulmonary syndrome. This disease has no specific treatment and has a high case fatality. The transmission of hantavirus to man occurs by inhaling aerosols of rodent excreta. The aim of this study was to determine the prevalence of antibodies to hantavirus in the population of the rural settlement of Tupã in the county of Marcelândia, state of Mato Grosso, Brazil.

METHODS

The participants of the serologic survey were visited at their homes and selected randomly among the settlement population. Blood samples of the participants were collected by venopuncture. The serum samples were tested by an IgG-ELISA using an N recombinant protein of Araraquara hantavirus as antigen, using the protocol previously established by Figueiredo et al.

RESULTS

IgG antibodies to hantavirus were detected in 7 (13%) of the 54 participants. The positivity was higher among men. It was observed that there was an association of seropositivity to hantavirus within the participants born in the south of Brazil.

CONCLUSIONS

The results suggest that, in this rural area, everyone is exposed to the same risk of becoming infected with hantavirus, and, therefore, there is a need to intensify surveillance activities and education of the local people to prevent this viral infection.

Seroprevalence of hantavirus and Yersinia pestis antibodies in professionals from the Plague control program

INTRODUCTION

Professionals who handle rodents in the field and in the laboratory are at risk of infection by the microorganis mharbored by these animals.

METHODS

Serum samples from professionals involved in rodent and Yersinia pestis handling in field or laboratory work were analyzed to determine hantavirus and plague seroprevalence and to establish a relationship between these activities and reports of illnesses.

RESULTS

Two individuals had antibodies against hantavirus, and two harbored antibodie against the plague; none of the individuals had experienced an illness related to their duties.

CONCLUSIONS

These results confirm the risks of hantavirus- and plague-related field and laboratory activities and the importance of protective measures for such work.

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.

Barn owl (Tyto alba) predation on small mammals and its role in the control of hantavirus natural reservoirs in a periurban area in southeastern Brazil

The aim of this study was to inventory the species of small mammals in Uberlândia, Minas Gerais, Brazil, based on regurgitated pellets of the barn owl and to compare the frequency of rodent species in the diet and in the environment. Since in the region there is a high incidence of hantavirus infection, we also evaluate the importance of the barn owl in the control of rodents that transmit the hantavirus. Data on richness and relative abundance of rodents in the municipality were provided by the Centro de Controle de Zoonoses, from three half-yearly samplings with live traps. In total, 736 food items were found from the analysis of 214 pellets and fragments. Mammals corresponded to 86.0% of food items and were represented by one species of marsupial (Gracilinanus agilis) and seven species of rodents, with Calomys tener (70.9%) and Necromys lasiurus (6.7%) being the most frequent. The proportion of rodent species in barn owl pellets differed from that observed in trap samplings, with Calomys expulsus, C. tener and Oligoryzomys nigripes being consumed more frequently than expected. Although restricted to a single place and based on few individuals, the present study allowed the inventory of eight species of small mammals in Uberlândia. The comparison of the relative frequencies of rodent species in the diet and in the environment indicated selectivity. The second most preyed upon species was N. lasiurus, the main hantavirus reservoir in the Cerrado biome. In this way, the barn owl might play an important role in the control of this rodent in the region, contributing to the avoidance of a higher number of cases of hantavirus infection.

[Climatic aspects in hantavirus transmission areas in São Paulo State, Brazil]

The objective of this study was to investigate the spatial distribution of reported hantavirus cases in São Paulo State, Brazil (n = 80), from 1993 to 2005 and identify local climatic patterns during this period. Kernel point estimation of density was used to show the highest concentrations in Ribeirão Preto, São Carlos, Franca, Tupi Paulista, and Greater São Paulo. Increase in the number of cases during this period suggests disease dissemination even when considering increased diagnostic capacity and higher sensitivity of the health services. There was a marked seasonal variation in hantavirus in the cerrado (savannah) areas; the common pattern is a higher incidence in drier months as compared to mean levels in the last 40 years. These coincide with periods of high rodent food source levels in grains, sugarcane, and other crops. Harvesting and storing grains increases human exposure to rodents. Climatic indicators together with ecological variables can be local transmission risk markers and should receive more attention in epidemiological monitoring and control of the disease.

[Hantavirus cardiopulmonary syndrome in the Triângulo Mineiro and Alto Paranaíba regions, State of Minas Gerais, 1998-2005: clinical-epidemiological aspects of 23 cases]

The epidemiological, clinical, laboratory and treatment findings from 23 cases of hantavirus cardiopulmonary syndrome were analyzed. These cases were identified either serologically or immunohistochemically in hospitals in the municipality of Uberlândia, State of Minas Gerais. Fever (100%), dyspnea (100%) and myalgia (78%) were the symptoms most frequently observed in this sample. The most prevalent physical signs were hypotension (65%) and tachycardia (65%). The most common laboratory findings included thrombocytopenia (96%), hemoconcentration (83%) and leukocytosis (74%). Abnormal values for liver enzymes were found in all the patients tested and abnormalities in chest radiography were very frequent (95.6%). In 55.5% of the patients, orotracheal intubation and hemodynamic support were required. The present study confirmed the seasonal pattern of hantavirus cardiopulmonary syndrome in the Uberlândia region and the involvement of professional groups who are considered to be at low risk of infection, in the transmission cycle of the disease. The high lethality rate (39%) and the severity of the disease observed in this study may be related to attending to these patients at a late stage.

A construção do conhecimento do indivíduo no processo de sensibilização-conscientização -ação sobre a hantavirose e a oportunidade para o controle e a prevenção de zoonoses emergentes: a experiência da hantavirose em Santa Catarina/Brasil

Este artigo descreve a trajetória da descoberta da Hantavirose no estado de Santa Catarina, no Município de Seara, no ano de 2000. Uma investigação epidemiológica dessa primeira ocorrência proveu dados e informações para pesquisa realizada a posteriori. O estudo realizado teve o intuito de analisar a Hantavirose como caso específico de doença emergente, relacionando-a com as suas condições de surgimento, passíveis de intervenção. Por meio de entrevistas semi-estruturadas com atores envolvidos na investigação, foram identificados aspectos relevantes para práticas da Saúde Pública. O pequeno aproveitamento dos dados de uma investigação epidemiológica; o pouco investimento em ações preventivas pelo Estado após a emergência; e a impessoalidade dos profissionais de saúde envolvidos a contribuir para a responsabilização dos indivíduos afetados constituíram elementos indicativos de que não há orientação e controle de forma contínua ou mesmo um auxílio real aos indivíduos/comunidades necessitadas. Dessa forma é praticamente impossível que as ações sanitárias sejam bem-sucedidas. Conclui-se que o Programa de Saúde na Família, de estratégia dinâmica e participativa, é um dos elementos fundamentais no processo de construção do conhecimento de cada indivíduo com importância inegável nas orientações diante da emergência da Hantavirose. Paralelo ao programa faz-se necessária a elaboração de projetos educacionais direcionados às escolas e de um cronograma de palestras para as associações de bairros, visando um processo de sensibilização - conscientização-ação no auto-cuidado, em caráter permanente e não somente por ocasião de epidemias.