Luiz Tadeu Moraes Figueiredo

A Global Perspective on Hantavirus Ecology, Epidemiology, and Disease

SUMMARY Hantaviruses are enzootic viruses that maintain persistent infections in their rodent hosts without apparent disease symptoms. The spillover of these viruses to humans can lead to one of two serious illnesses, hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. In recent years, there has been an improved understanding of the epidemiology, pathogenesis, and natural history of these viruses following an increase in the number of outbreaks in the Americas. In this review, current concepts regarding the ecology of and disease associated with these serious human pathogens are presented. Priorities for future research suggest an integration of the ecology and evolution of these and other host-virus ecosystems through modeling and hypothesis-driven research with the risk of emergence, host switching/spillover, and disease transmission to humans.

Duplex Reverse Transcription-PCR Followed by Nested PCR Assays for Detection and Identification of Brazilian Alphaviruses and Flaviviruses

ABSTRACT A new approach was developed for the rapid detection and identification of Brazilian alphaviruses and flaviviruses. The methodology involves the genus-specific detection of Alphavirus and Flavivirus by a duplex reverse transcription-PCR (D-RT-PCR), followed by multiplex nested PCR (M-N-PCR) or nested PCR (N-PCR) assays for species-specific identification. By this protocol, 25 arboviruses were specifically detected and identified. Detection levels between 101.3 and 103.5 50% tissue culture infective doses (TCID50)/ml of Flavivirus and Alphavirus strains were achieved by D-RT-PCR, and levels of <1 TCID50/ml were achieved by M-N-PCR assays. To assess the suitability and clinical application of this methodology, a total of 101 human or animal stored samples were analyzed. Results obtained suggest that this technique could be applied as a rapid diagnostic tool in clinical samples in which arbovirus infection is suspected and differential diagnosis is required, avoiding the need to test specimens by separate PCR methods.

The Brazilian flaviviruses.

Ten flaviviruses occur in Brazil: Bussuquara, Cacipacoré, dengue 1, 2 and 4, Iguape, Ilhéus, Rocio, Saint Louis encephalitis and yellow fever. Aspects of sylvatic maintenance cycles and human diseases caused by these viruses are analyzed. Large dengue outbreaks are occurring in Brazil and there is a risk of yellow fever urbanization.

Emergent arboviruses in Brazil

O Brasil e pais tropical de grande extensao territorial (8.514.215km2) e com 185.360.000 habitantes. Mais de 1/3 deste territorio e recoberto por florestas tropicais ou outros ecossistemas naturais com condicoes ideais para a ocorrencia de diversas arboviroses as quais sao mantidas em uma grande variedade de ciclos zoonoticos. O risco para a emergencia de novos arbovirus no Brasil relaciona-se a existencia de cidades grandes, populosas e infestadas por mosquitos Culex bem como o altamente antropofilico Aedes aegypti. Nas cidades poderiam ser introduzidos seres humanos ou animais infectados oriundos de sitios eco-epidemiologicos onde existem zoonoses arboviricas. Neste trabalho, analisa-se o risco de emergencia dos alphavirus Mayaro, da encefalite equina venezuelana, da encefalite equina do leste e Chikungunya, dos flavivirus, da febre amarela, Rocio, da encefalite de Saint Louis e do Nilo Ocidental, e do orthobunyavirus Oropouche.Brazil is a large tropical country (8,514,215 km(2)) with 185,360,000 inhabitants. More than one third of its territory is covered by tropical forests or other natural ecosystems. These provide ideal conditions for the existence of many arboviruses, which are maintained in a large variety of zoonotic cycles. The risk that new arboviruses might emerge in Brazil is related to the existence of large, densely populated cities that are infested by mosquitoes such as Culex and the highly anthropophilic Aedes aegypti. Infected humans or animals may come into these cities from ecological-epidemiological settings where arbovirus zoonoses occur. This study analyzes the risk of emergence of the alphaviruses Mayaro, Venezuelan equine encephalitis, Eastern equine encephalitis and Chikungunya; the flaviviruses yellow fever, Rocio, Saint Louis encephalitis and West Nile; and the orthobunyavirus Oropouche.

Detection of dengue virus in saliva and urine by real time RT-PCR

Early diagnosis of dengue virus (DENV) infection is important for patient management and control of dengue outbreaks. The objective of this study was to analyze the usefulness of urine and saliva samples for early diagnosis of DENV infection by real time RT-PCR. Two febrile patients, who have been attended at the General Hospital of the School of Medicine of Ribeirao Preto, Sao Paulo University were included in the study. Serum, urine and saliva samples collected from both patients were subjected to real time RT-PCR for DENV detection and quantification. Dengue RNA was detected in serum, urine and saliva samples of both patients. Patient 1 was infected with DENV-2 and patient 2 with DENV-3. Data presented in this study suggest that urine and saliva could be used as alternative samples for early diagnosis of dengue virus infection when blood samples are difficult to obtain, e.g., in newborns and patients with hemorrhagic syndromes.

Congenital cytomegalovirus infection in preterm and full-term newborn infants from a population with a high seroprevalence rate.

BACKGROUND Cytomegalovirus (CMV) is the most frequent cause of congenital infections in humans. Prematurity occurs in as many as 34% of infants with symptomatic congenital CMV infection. OBJECTIVE To determine the clinical presentation and frequency of congenital CMV infection among preterm infants and full-term infants from a population with a high seroprevalence rate. DESIGN/METHODS A total of 289 preterm infants (median gestational age, 34 weeks; median birth weight, 1,757 g) and 163 term infants (median gestational age, 39 weeks; median birth weight, 3,150 g) sequentially born were included in the study. Serum IgG antibodies to CMV were measured in all mothers. One urine sample was collected within the first 7 days of age from all newborns. Virus isolation in urine samples was performed by tissue culture, and viral DNA was detected by a multiplex PCR. CMV infection was diagnosed in infants with virus excretion detected by both methods on at least two occasions within the first 3 weeks of life. RESULTS Maternal CMV seropositivity rate was 95.7%. Congenital CMV infection was detected in 6 of 289 (2.1%) (95% confidence interval, 0.84 to 4.68) preterm infants and in 3 of 163 term infants (1.8%) (95% confidence interval, 0.48 to 5.74) (P > 0.05). Four of 6 preterm infants with congenital CMV infection were symptomatic, but none of the term infants was symptomatic (P = 0.16). CONCLUSION The frequency of congenital CMV infection in preterm newborn infants from mothers with a high seropositive rate was similar to that found in term infants. No significant difference was found between the proportion of symptomatic infants among preterm and term infants. Our finding of symptomatic congenital CMV infection underscores the need of further evaluation of correlates of congenital symptomatic infection in highly immune populations.

Hantavirus Pulmonary Syndrome, Central Plateau, Southeastern, and Southern Brazil

This syndrome is an increasing health problem because of human encroachment into habitats of rodent reservoirs.

Domain III peptides from flavivirus envelope protein are useful antigens for serologic diagnosis and targets for immunization.

The Flavivirus genus of the Flaviviridae family includes 70 enveloped single-stranded-RNA positive-sense viruses transmitted by arthropods. Among these viruses, there are a relevant number of human pathogens including the mosquito-borne dengue virus (DENV), yellow fever virus (YFV), Japanese encephalitis virus (JEV) and West Nile virus (WNV), as well as tick-borne viruses such as tick-borne encephalitis virus (TBEV), Langat virus (LGTV) and Omsk hemorrhagic fever (OHFV). The flavivirus envelope (E) protein is a dominant antigen inducing immunologic responses in infected hosts and eliciting virus-neutralizing antibodies. The domain III (DIII) of E protein contains a panel of important epitopes that are recognized by virus-neutralizing monoclonal antibodies. Peptides of the DIII have been used with promising results as antigens for flavivirus serologic diagnosis and as targets for immunization against these viruses. We review here some important aspects of the molecular structure of the DIII as well as its use as antigens for serologic diagnosis and immunization in animal models.

Hantaviruses--globally emerging pathogens.

Hantaviruses are emerging zoonotic viruses which cause human disease in Africa, America, Asia, and Europe. This review summarizes the progress in hantavirus epidemiology and diagnostics during the previous decade. Moreover, we discuss the influence of ecological factors on the worldwide virus distribution and give an outlook on research perspectives for the next years.

Congenital and perinatal cytomegalovirus infection in infants born to mothers infected with human immunodeficiency virus

OBJECTIVES To determine the rates of congenital and perinatal cytomegalovirus (CMV) infection among infants born to mothers infected with HIV compared with infants born to mothers not infected with HIV from a CMV-immune, low-income population. STUDY DESIGN A total of 325 newborns from CMV-seropositive mothers were enrolled and evaluated for congenital CMV infection (150 infants from HIV+ mothers and 175 infants from HIV- mothers. A total of 101 infants from HIV+ mothers and 33 infants from HIV- mothers were evaluated for perinatal CMV infection. The virus was isolated from urine by culture in human fibroblasts and was detected by polymerase chain reaction at birth and at 15 days and 12 weeks of age. RESULTS Only 13 of 150 HIV+ mothers (8.7%) had an AIDS-defining condition, and none had a late-stage HIV infection. Congenital CMV infection was detected in 4 of 150 (2.7%) infants from HIV+ mothers and in 5 of 175 (2.9%) infants from HIV- mothers (p = 1.00). Perinatal CMV infection was diagnosed in 8 of 101 (7.9%) infants from HIV+ mothers and in 13 of 33 (39.4%) infants from HIV- mothers (p < 0.00001). Most infants (93.9%) from HIV- mothers and only 5.9% of infants from HIV+ mothers were breastfed. CONCLUSIONS CMV coinfection in mothers without advanced HIV disease from a CMV-immune population does not enhance the likelihood of congenital CMV infection. Perinatal CMV transmission from HIV-infected mothers may be decreased by avoiding breastfeeding. Further studies on mothers with late-stage HIV infection are needed.