Laboratory diagnosis of hantavirus cardiopulmonary syndrome (HCPS) in Brazil has been performed mostly by detection of IgM antibodies to recombinant antigen purified from Sin Nombre virus and Andes virus (ANDV). Recently, a recombinant nucleocapsid (rN) protein of Araraquara virus (ARAV), a Brazilian hantavirus, was obtained in Escherichia coli. To evaluate ARAV rN as antigen for antibody detection, serum samples from 30 patients from Argentina seropositive for hantavirus were tested. All samples were positive for IgG and IgM by enzyme-linked immunosorbent assay (ELISA) using either ARAV rN or ANDV rN antigens. In Brazil, six of 60 serum samples from patients with suspected HCPS (10%) were positive for IgM by ELISA using ARAV rN antigen and 7 were positive using ANDV rN antigen. For results obtained with 90 serum samples analyzed by IgM ELISA with ANDV rN antigen, the sensitivity of the IgM ELISA using ARAV rN antigen was 97.2%, the specificity was 100%, the positive predictive value was 100%, and the negative predictive value was 98.1%. The results show that ARAV rN is a suitable antigen for diagnosis of hantavirus infection in Brazil and Argentina.

Hantaviruses are the causative agents of severe human diseases such as Cardiopulmonary Syndrome (CPS), described for the first time in 1993. Approximately 200 cases of this emergent disease were reported in Brazil until August 2002, with a 40% fatality rate. In May 2001, a hantavirus serologic survey was carried out among 15-70-year-old inhabitants of Jardinopolis County, State of São Paulo, Brazil. Blood samples of 818 inhabitants from urban and rural areas were collected by digitopuncture and IgG antibodies, detected by an indirect enzyme-linked immunosorbent assay (ELISA) to the N recombinant protein of Andes hantavirus, were found in 14.3% of the samples, showing that this infection is common in Jardinopolis County, especially among adults irrespective of sex, profession, history of contact with rodents, or history of severe pneumonia. The results of the survey do not corroborate the idea that hantavirus infections are associated to rural activity and rodent contact, as observed with 20 Cardiopulmonary Syndrome cases occurred in the same region. Hantaviruses may be causing unrecognized infections, either asymptomatic or clinically nonspecific in addition to the syndrome. It may also be the case that more than one hantavirus type could be circulating in this region, causing mostly benign infections.

Dengue is the most important arbovirus disease in tropical and sub-tropical countries, and can be caused by infection with any of the four-dengue virus (DENV) serotypes. Infection with DENV can lead to a broad clinical spectrum, ranging from sub-clinical infection or an influenza-like disease known as dengue fever (DF) to a severe, sometimes fatal, disease characterized by hemorrhage and plasma leakage that can lead to shock, known as dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS). The diagnosis of dengue is routinely accomplished by serologic assays, such as IgM and IgG ELISAs, as well as HI tests, analyzing serum samples obtained from patients with at least 7 days of symptoms onset. These tests cannot be used for diagnosis during the early symptomatic phase. In addition, antibodies against dengue are broad reactive with other flaviviruses. Therefore, a specific diagnostic method for acute DENV infection is of great interest. In that sense, the real-time RT-PCR has become an important tool that can be used for early and specific detection of dengue virus genome in human serum samples. This study describes a simple, specific, and sensitive real-time RT-PCR for early diagnosis of dengue virus infection.

Specimens of ticks were collected in 1993, 1996, 1997, and 1998, mostly from wild and domestic animals in the Southeast and Mid-West regions of Brazil. Nine species of Amblyommidae were identified: Anocentor nitens, Amblyomma cajennense, Amblyomma ovale, Amblyomma fulvum, Amblyomma striatum, Amblyomma rotundatum, Boophilus microplus, Boophilus annulatus, and Rhipicephalus sanguineus. The potential of these tick species as transmitters of pathogens to man was analyzed. A Flaviviridade Flavivirus was isolated from Amblyomma cajennense specimens collected from a sick capybara (Hydrochaeris hydrochaeris). Amblyomma cajennense is the main transmitter of Rickettsia rickettsii (=R. rickettsi), the causative agent of spotted fever in Brazil. Wild mammals, mainly capybaras and deer, infested by ticks and living in close contact with cattle, horses and dogs, offer the risk of transmission of wild zoonosis to these domestic animals and to man. Key-words: Brazilian ticks. Tick-borne pathogens. Resumo

Activation of the immune response in hantavirus cardiopulmonary syndrome (HCPS) leads to a high TNF production, probably contributing to the disease. The polymorphic TNF2 allele (TNF -308G/A) has been associated with increased cytokine production. We investigated the association of the TNF2 allele with the outcome of hantavirus infection in Brazilian patients. A total of 122 hantavirus-exposed individuals (26 presenting HCPS and 96 only hantavirus seroconversion) were studied. The TNF2 allele was more frequently found in HCPS patients than in individuals with positive serology for hantavirus but without a history of HCPS illness, suggesting that the TNF2 allele could represent a risk factor for developing HCPS.