Moreno Souza Rodrigues

Outbreak of Exanthematous Illness Associated with Zika, Chikungunya, and Dengue Viruses, Salvador, Brazil

To the Editor: Zika virus (ZIKV) has been recognized as an emerging mosquito-borne flavivirus since outbreaks were reported from Yap Island in 2007 (1), French Polynesia in 2013 (2), and Cook Island and New Caledonia in 2014 (3). It has joined dengue virus (DENV) and chikungunya virus (CHIKV) as global public health threats (4). ZIKV infection typically causes a self-limited dengue-like illness characterized by exanthema, low-grade fever, conjunctivitis, and arthralgia, and an increase in rates of Guillain-Barre syndrome have been observed during ZIKV outbreaks (5). In Brazil, clusters of cases of acute exanthematous illness have been reported from various regions since late 2014, and in April 2015, ZIKV was identified as the etiologic agent (6). In May 2015, the Brazilian Ministry of Health recognized circulation of ZIKV in Brazil. We report epidemiologic findings for an ongoing outbreak of acute exanthematous illness in the population of Salvador, the third largest city in Brazil. The Salvador Epidemiologic Surveillance Office (ESO) was first alerted to cases of an acute exanthematous illness early in 2015. Reporting of cases increased during March, and in April the ESO established 10 public emergency health centers in Salvador as sentinel units for systematic surveillance of patients with acute exanthematous illness of unknown cause. The units searched retrospectively for suspected cases by review of medical charts of patients treated since February 15, continued with prospective case detection, and submitted weekly reports of identified cases to the ESO. During February 15−June 25, a total of 14,835 cases of an indeterminate acute exanthematous illness were reported from the 12 sanitary districts in Salvador. The overall attack rate was 5.5 cases/1,000 persons (4.6 cases/1,000 men and 6.3 cases/1,000 women, 8.2 cases/1,000 children 40 years of age). The epidemic curve peaked in the first week of May, which was 1 week after molecular diagnosis of ZIKV in 8 patients residing ≈50 km from Salvador and during a period of intense media coverage of the outbreak (Figure) (6). Reporting of suspected dengue cases in Salvador did not vary substantially from that in other years and was >5 times lower: 2,630 cases, of which 165/366 (45.1%) were positive for dengue IgM, 20/590 (3.4%) positive for dengue virus nonstructural protein 1, and 1/11 (9.1%) positive for dengue virus by reverse transcription PCR (Figure). During the same period, 58 cases of suspected chikungunya were reported and 24 patients with suspected Guillain-Barre syndrome were hospitalized. Figure Reported cases of indeterminate acute exanthematous illness and suspected dengue fever in Salvador, Brazil, by date of medical care, February 15−June 25, 2015. Letters indicate specific events. A) February 15: systematic reporting of cases of ... The median age of case-patients was 26 years (interquartile range 11–39 years), but all age groups were affected, which is a pattern typical of spread of new microorganisms (or subtypes) in a susceptible population. Median duration of symptoms at time of medical attention was 1 day (interquartile range 0–3 days). All patients had exanthema and most (12,711/14,093 [90.2%]) had pruritus. Fever (4,841/13,786, 35.1%), arthralgia (278/1,048 [26.5%]), headache (3,446/13,503 [25.6%]), and myalgia (223/1,033 [21.6%]) were less common. Serum samples from some patients were examined for rubella IgM (2/200, 1.0% positive), rubella IgG (15/18, 83.3% positive), measles IgM (0/11, 0% positive), dengue nonstructural protein 1 (3/185, 1.6% positive), dengue IgM (17/80, 21.3% positive), parvovirus B19 IgM (0/1, 0% positive), and parvovirus B19 IgG (1/1, 100% positive). Reverse transcription PCR was performed on 58 serum samples stored at −20°C and confirmed ZIKV in 3 (5.2%) samples, CHIKV in 3 (5.2%) samples, DENV type 3 in 1 (1.7%) sample, and DENV type 4 in 1 (1.7%) sample. Identification of ZIKV, CHIKV and DENV as etiologic agents of acute exanthematous illness suggests that these 3 Aedes spp. mosquito−transmitted viruses were co-circulating in Salvador and highlights the challenge in clinically differentiating these infections during outbreaks. Although we were not able to determine the specific incidence of each virus, the low frequency of fever and arthralgia, which are indicators of dengue and chikungunya, point to ZIKV as the probable cause of several of the reported cases. Furthermore, laboratory-confirmed cases of infection with ZIKV were simultaneously identified in other cities within metropolitan Salvador (6,7) and in other states in Brazil (8). Low diagnosis of ZIKV infection is likely because viremia levels among infected patients appear to be low (9). The spread of ZIKV represents an additional challenge for public health systems, particularly because of the risk for concurrent transmission of DENV and CHIKV by the same vectors, Ae. aegypti and Ae. albopictus mosquitoes, which are abundant throughout tropical and subtropical regions. To date, the largest outbreak of chikungunya in Brazil occurred in 2014 in Feira de Santana, Bahia, ≈100 km from Salvador, where dengue is also prevalent (10). This report illustrates the potential for explosive simultaneous outbreaks of ZIKV, CHIKV, and DENV in the Western Hemisphere and the increasing public health effects of Aedes spp. mosquitoes as vectors. The apparent increase in reports of Guillain-Barre syndrome during the outbreak deserves further investigation to elucidate whether this syndrome is associated with ZIKV infection. Public health authorities in Brazil and neighboring countries should plan accordingly.

Accuracy of Dengue Reporting by National Surveillance System, Brazil.

To the Editor: Dengue is an underreported disease globally. In 2010, the World Health Organization recorded 2.2 million dengue cases (1), but models projected that the number of symptomatic dengue cases might have been as high as 96 million (2). Brazil reports more cases of dengue than any other country (1); however, the degree of dengue underreporting in Brazil is unknown. We conducted a study to evaluate dengue underreporting by Brazil’s Notifiable Diseases Information System (Sistema de Informacao de Agravos de Notificacao [SINAN]). From January 1, 2009, through December 31, 2011, we performed enhanced surveillance for acute febrile illness (AFI) in a public emergency unit in Salvador, Brazil. The surveillance team enrolled outpatients >5 years of age with measured (>37.8°C) or reported fever. Patients or their legal guardians provided written consent. The study was approved by the Oswaldo Cruz Foundation Ethics Committee, Brazil’s National Council for Ethics in Research, and the Yale Institutional Review Board. We collected participants’ blood samples at study enrollment and >15 days later. Acute-phase serum samples were tested by dengue nonstructural protein 1 ELISA and IgM ELISA (Panbio Diagnostics, East Brisbane, Queensland, Australia). Convalescent-phase serum samples were tested by IgM ELISA. In concordance with case-reporting guidelines in Brazil (3), we defined dengue cases by a positive nonstructural protein 1 ELISA result or a positive acute-phase or convalescent-phase IgM ELISA result. All others were classified as nondengue AFI. We then identified which study patients were officially reported to SINAN as having a suspected case of dengue. In Brazil, notification of suspected dengue cases is mandatory. A suspected case is defined as illness in a person from an area of dengue transmission or Aedes aegypti mosquito infestation who has symptoms of dengue (fever of 2 of the following symptoms: nausea/vomiting, exanthema, myalgia, arthralgia, headache, retro-orbital pain, petechiae/positive tourniquet test, or leukopenia). We used Link Plus software (CDC-Link Plus Production 2.0; Centers for Disease Control and Prevention, Atlanta, GA, USA) to perform probabilistic record linkage from our database with official reports in the SINAN database. The records were matched based on the patients’ first names, last names, and dates of birth. We then manually reviewed the matches to confirm the pairs. On the basis of the results, we calculated the sensitivity, specificity, positive predictive value (PPV), and negative predictive value of the national surveillance system. We calculated accuracy measurements with 95% CIs for the overall study period and for each study year, age group (5–14 vs. >15 years), and seasonal prevalence of dengue (months of low vs. high dengue transmission, defined by dengue detection in 20% of the AFI patients, respectively). We estimated multiplication factors by dividing the number of dengue cases in our study by the number of study patients who were reported to SINAN as having dengue. Of the 3,864 AFI patients identified during the 3-year study period, 997 (25.8%) had laboratory evidence of dengue infection, and 2,867 (74.2%) were classified as having nondengue AFI. Of the 997 dengue cases, 57 were reported to SINAN (sensitivity 5.7%) (Table). Of the 2,867 nondengue AFI cases, 26 were reported to SINAN as dengue cases (false-positive ratio 0.9%, specificity 99.1%). None of these 26 cases had laboratory confirmation in the SINAN database. The PPV for reporting to SINAN was 68.7%, and the negative predictive value was 75.1% (Table). PPV was higher among patients >15 years of age, which might be attributable to atypical presentations of dengue in children (4,5). Table Accuracy of a national surveillance system for recording cases of suspected dengue among patients with acute febrile illness who visited an emergency health unit of Salvador, Brazil, January 1, 2009–December 31, 2011* We found that 1 in 4 patients with AFI had laboratory evidence of dengue infection. However, for every 20 dengue patients that we identified, only about 1 had been reported to SINAN as having dengue. During periods of low dengue transmission, only about 1 in 40 dengue cases identified was reported. Conversely, among the patients who were reported as having dengue, 31.2% did not have the disease; this percentage reached 61.5% in low-transmission periods. We estimated that overall, there were 12 dengue cases per reported case in the community, but in months of low dengue transmission, this ratio was >17:1 (Table). Comparable results have been observed in Nicaragua, Thailand, and Cambodia (6–8). By applying the estimated multiplication factor to the study period’s mean annual incidence of 303.8 reported dengue cases/100,000 Salvador residents (9), we estimated that the actual mean annual dengue incidence for Salvador was 3,645.7 cases/100,000 residents. We showed that dengue surveillance substantially underestimated disease burden in Brazil, especially in what are considered low-transmission periods. Dengue underreporting has been attributed to passive case detection, which fails to identify persons with dengue who do not seek health care (1). We also showed that surveillance failed to detect dengue cases among symptomatic patients seeking health care. Novel surveillance tools, such as active syndromic surveillance and point-of-care testing, should be applied to improve estimates of dengue incidence. Furthermore, given the recent emergence of chikungunya and Zika viruses in Brazil (10), improved surveillance and laboratory diagnostics are needed to avert misclassification and mismanagement of cases.

Spatial Distribution of Dengue in a Brazilian Urban Slum Setting: Role of Socioeconomic Gradient in Disease Risk

Background Few studies of dengue have shown group-level associations between demographic, socioeconomic, or geographic characteristics and the spatial distribution of dengue within small urban areas. This study aimed to examine whether specific characteristics of an urban slum community were associated with the risk of dengue disease. Methodology/Principal Findings From 01/2009 to 12/2010, we conducted enhanced, community-based surveillance in the only public emergency unit in a slum in Salvador, Brazil to identify acute febrile illness (AFI) patients with laboratory evidence of dengue infection. Patient households were geocoded within census tracts (CTs). Demographic, socioeconomic, and geographical data were obtained from the 2010 national census. Associations between CTs characteristics and the spatial risk of both dengue and non-dengue AFI were assessed by Poisson log-normal and conditional auto-regressive models (CAR). We identified 651 (22.0%) dengue cases among 2,962 AFI patients. Estimated risk of symptomatic dengue was 21.3 and 70.2 cases per 10,000 inhabitants in 2009 and 2010, respectively. All the four dengue serotypes were identified, but DENV2 predominated (DENV1: 8.1%; DENV2: 90.7%; DENV3: 0.4%; DENV4: 0.8%). Multivariable CAR regression analysis showed increased dengue risk in CTs with poorer inhabitants (RR: 1.02 for each percent increase in the frequency of families earning ≤1 times the minimum wage; 95% CI: 1.01-1.04), and decreased risk in CTs located farther from the health unit (RR: 0.87 for each 100 meter increase; 95% CI: 0.80-0.94). The same CTs characteristics were also associated with non-dengue AFI risk. Conclusions/Significance This study highlights the large burden of symptomatic dengue on individuals living in urban slums in Brazil. Lower neighborhood socioeconomic status was independently associated with increased risk of dengue, indicating that within slum communities with high levels of absolute poverty, factors associated with the social gradient influence dengue transmission. In addition, poor geographic access to health services may be a barrier to identifying both dengue and non-dengue AFI cases. Therefore, further spatial studies should account for this potential source of bias.

Ecological aspects and molecular detection of Leishmania DNA Ross (Kinetoplastida: Trypanosomatidae) in phlebotomine sandflies (Diptera: Psychodidae) in terra firme and várzea environments in the Middle Solimões Region, Amazonas State, Brazil

BackgroundPhlebotomine sand flies (Diptera: Psychodidae) are insects of medical importance due to the role that some species play in the transmission of leishmaniasis. This work aimed to study some ecological aspects among sand flies fauna inhabiting two different environments: the várzea (lowland Amazonian forest) and terra firme (upland Amazonian forest), both located in Tefé Municipality, Amazonas State, Braziland to detect Leishmania infection in those phlebotomine populations.MethodsSand flies were collected using HP light traps. Collection took place over the course of six months: January, February, April, August, September, and October of 2013. To detect natural infection by Leishmania, DNA samples were extracted from female sand flies and submitted to Polymerase Chain Reaction (PCR) targeting the kDNA gene; Leishmania species were identified by PCR-RFLP targeting the hsp70 gene and genetic sequencing.ResultsIn all, 5,716 individuals were collected, and 46 species were identified. Trichophoromyia ubiquitalis (3,330 – 58.26%) and Nyssomyia antunesi (661 – 11.26%) were the most abundant species. Species richness was greater in terra firme environments (42 species) than in the várzea environments (22 species), and forests ecotopes (43 species) were richer than peridomiciles (28 species). DNA of Leishmania was found in Th. ubiquitalis and Psychodopygus davisi, both of which inhabit the terra firme environment and sequencing analysis confirmed the presence of Leishmania (Viannia) lainsoni DNA in Th. ubiquitalis in Tefé Municipality.ConclusionsThe high abundance of Th. ubiquitalis and Ps. davisi and detection of DNA of Leishmania sp. may indicate that both species could be putative vectors for American Cutaneous Leishmaniasis (ACL) in the terra firme environment of Tefé. The sand fly fauna found in várzea is rich and diverse, exhibiting several species, nevertheless the seasonal hydric stress during part of the year that could influence the local diversity, if compared with other studies. This is the first report in Amazonas State of Th. ubiquitalis with presence of L. (V.) lainsoni DNA.

Phlebotomine sandfly (Diptera: Psychodidae) diversity and their Leishmania DNA in a hot spot of American Cutaneous Leishmaniasis human cases along the Brazilian border with Peru and Bolivia.

In this study, we identified the phlebotomine sandfly vectors involved in the transmission of American Cutaneous Leishmaniasis (ACL) in Assis Brasil, Acre, Brazil, which is located on the Brazil-Peru-Bolivia frontier. The genotyping of Leishmania in phlebotomines was performed using polymerase chain reaction (PCR) and PCR-restriction fragment length polymorphism. A total of 6,850 sandflies comprising 67 species were captured by using CDC light traps in rural areas of the municipality. Three sandfly species were found in the state of Acre for the first time: Lutzomyia georgii, Lu. complexa and Lu. evangelistai. The predominant species was Lu. auraensis/Lu. ruifreitasi and Lu. davisi (total 59.27%). 32 of 368 pools were positive for the presence of Leishmania DNA (16 pools corresponding to Lu. davisi, and 16 corresponding to Lu. auraensis/Lu. ruifreitasi), with a minimal infection prevalence of 1.85% in Lu. davisi and 2.05% in Lu. auraensis/Lu. ruifreitasi. The Leishmania species found showed maximum identity with L. (Viannia) guyanensis and L. (V.) braziliensis in both phlebotomine species. Based on these results and similar scenarios previously described along the Brazil/Peru/Bolivia tri-border, the studied area must take into consideration the possibility of Lu. davisi and Lu. auraensis/Lu. ruifreitasi as probable vectors of ACL in this municipality.

SEASONAL DISTRIBUTION OF MALARIA VECTORS (DIPTERA: CULICIDAE) IN RURAL LOCALITIES OF PORTO VELHO, RONDÔNIA, BRAZILIAN AMAZON

We conducted a survey of the malaria vectors in an area where a power line had been constructed, between the municipalities of Porto Velho and Rio Branco, in the states of Rondônia and Acre, respectively. The present paper relates to the results of the survey of Anopheles fauna conducted in the state of Rondônia. Mosquito field collections were performed in six villages along the federal highway BR 364 in the municipality of Porto Velho, namely Porto Velho, Jaci Paraná, Mutum Paraná, Vila Abunã, Vista Alegre do Abunã, and Extrema. Mosquito captures were performed at three distinct sites in each locality during the months of February, July, and October 2011 using a protected human-landing catch method; outdoor and indoor captures were conducted simultaneously at each site for six hours. In the six sampled areas, we captured 2,185 mosquitoes belonging to seven Anopheles species. Of these specimens, 95.1% consisted of Anopheles darlingi, 1.8% An. triannulatus l.s., 1.7% An. deaneorum, 0.8% An. konderi l.s., 0.4 An. braziliensis, 0.1% An. albitarsis l.s., and 0.1% An. benarrochi. An. darlingi was the only species found in all localities; the remaining species occurred in sites with specific characteristics.

Mansonella ozzardi in the municipality of Tefé, Amazonas, Brazil, 60 years after the first report: an epidemiologic study

The prevalence of mansonelliasis was studied in the municipality of Tefé, state of Amazonas, Brazil. The prevalence (thick blood smear method) was 13.6% (147/1,078), higher in the Solimões River region (16.3%) than in the Tefé River region (6.3%). In the sampled communities in the Solimões River region, a higher density of cases was observed, as indicated by a kernel analysis (odds ratio 0.34; 95% confidence interval: 0.20-0.57). Males had a higher prevalence (χ2 = 31.292, p < 0.001) than women. Mansonella ozzardi prevalence was higher in retirees and farmers (28.9% and 27%, respectively). Prevalence also significantly increased with age (χ2 = -128.17, p < 0.001), with the highest numbers occurring in persons older than 67 years.

Epidemiological snapshot of the mansonelliasis infection in the Amazonian riverine communities in two contiguous municipalities of Solimões river, Amazonas State, Brazil

This study was conducted to gather updated information on the occurrence of Mansonella ozzardi in Codajas, and report new information about filaria found in the riverine communities of Coari, Amazonas State, Brazil. The prevalence (thick blood smear) of infection was 9.4% and 22.0% in Codajas and Coari, respectively. Men (17.1%) had a higher prevalence than women (11.2%) (ANOVA χ2 = -4.93; p = 0.02); and the rates significantly increased with age (ANOVA χ2 = -11.51; p < 0.001) and in certain occupations such as farming/fishing (29.2%) and retired (27.6%). Municipalities located in the Solimoes river have attracted large numbers of migrant workers due to oil and gas exploration in the area, and this may facilitate the spread of filariasis to other non-endemic areas.

Epidemiological study of snakebite cases in Brazilian Western Amazonia

INTRODUCTION Brazil has the largest number of snakebite cases in South America, of which the large majority is concentrated in the Midwest and North. METHODS In this descriptive observational study, we assessed the epidemiological and clinical snakebite cases referred to the Centro de Medicina Tropical de Rondônia from September 2008 to September 2010. RESULTS We followed up 92 cases from admission until discharge, namely 81 (88%) men and 11 (12%) women, with a mean age of 37 years, and mainly from rural areas (91.3%). The snakebites occurred while performing work activities (63%) during the Amazon rainy season (78.3%). The vast majority of individuals presented from the Porto Velho microregion (84.7%). Approximately 95.6% of the snakebites were caused by snakes of the genus Bothrops, followed by two lachetics and two elapidics cases. Surgery was performed in 10 cases (9 fasciotomies in the lower limb and 1 amputation). No deaths were reported in this study, but 4 cases (4.3%) developed sequelae in the lower limb. CONCLUSIONS This study can contribute to a better understanding of envenomation in the state of Rondônia and thus can be useful for identifying real conditions that can increase the incidence of snakebites in this region. Moreover, the study results can serve as a basis for improving educational campaigns designed to prevent these types of snakebites, as well as for preserving snakes.

Follow up of a robust meta-signature to identify Zika virus infection in Aedes aegypti: another brick in the wall

The mosquito Aedes aegypti is the main vector of several arthropod-borne diseases that have global impacts. In a previous meta-analysis, our group identified a vector gene set containing 110 genes strongly associated with infections of dengue, West Nile and yellow fever viruses. Of these 110 genes, four genes allowed a highly accurate classification of infected status. More recently, a new study of Ae. aegypti infected with Zika virus (ZIKV) was published, providing new data to investigate whether this “infection” gene set is also altered during a ZIKV infection. Our hypothesis is that the infection-associated signature may also serve as a proxy to classify the ZIKV infection in the vector. Raw data associated with the NCBI/BioProject were downloaded and re-analysed. A total of 18 paired-end replicates corresponding to three ZIKV-infected samples and three controls were included in this study. The nMDS technique with a logistic regression was used to obtain the probabilities of belonging to a given class. Thus, to compare both gene sets, we used the area under the curve and performed a comparison using the bootstrap method. Our meta-signature was able to separate the infected mosquitoes from the controls with good predictive power to classify the Zika-infected mosquitoes.