Maria Paula Gomes Mourão

Severe Plasmodium vivax Malaria, Brazilian Amazon

We describe a case series of 17 patients hospitalized in Manaus (western Brazilian Amazon) with PCR-confirmed Plasmodium vivax infection who were treated with chloroquine and primaquine. The major complications were jaundice and severe anemia. No in vivo chloroquine resistance was detected. These data help characterize the clinical profile of severe P. vivax malaria in Latin America.

Dengue Virus Type 4, Manaus, Brazil

We report dengue virus type 4 (DENV-4) in Amazonas, Brazil. This virus was isolated from serum samples of 3 patients treated at a tropical medicine reference center in Manaus. All 3 cases were confirmed by serologic and molecular tests; 1 patient was co-infected with DENV-3 and DENV-4.

Thrombocytopenia in malaria: who cares?

Despite not being a criterion for severe malaria, thrombocytopenia is one of the most common complications of both Plasmodium vivax and Plasmodium falciparum malaria. In a systematic review of the literature, platelet counts under 150,000/mm³ ranged from 24-94% in patients with acute malaria and this frequency was not different between the two major species that affected humans. Minor bleeding is mentioned in case reports of patients with P. vivax infection and may be explained by medullary compensation with the release of mega platelets in the peripheral circulation by megakaryocytes, thus maintaining a good primary haemostasis. The speculated mechanisms leading to thrombocytopenia are: coagulation disturbances, splenomegaly, bone marrow alterations, antibody-mediated platelet destruction, oxidative stress and the role of platelets as cofactors in triggering severe malaria. Data from experimental models are presented and, despite not being rare, there is no clear recommendation on the adequate management of this haematological complication. In most cases, a conservative approach is adopted and platelet counts usually revert to normal ranges a few days after efficacious antimalarial treatment. More studies are needed to specifically clarify if thrombocytopenia is the cause or consequence of the clinical disease spectrum.

Mayaro Fever in the City of Manaus, Brazil, 2007–2008

Mayaro Alphavirus is an arbovirus that causes outbreaks of acute febrile illness in the Amazon region of South America. We show here the cases of Mayaro fever that occurred in 2007-2008, in Manaus, a large city and capital of the Amazonas State, in Western Brazilian Amazon. IgM antibodies to Mayaro virus (MAYV) were detected by an enzyme immunoassay using infected cell cultures as antigen in the sera of 33 patients from both genera and 6-65 years old. MAYV genome was also detected by RT-PCR in the blood of 1/33 of these patients. The patients presented mainly with headache, arthralgia, myalgia, ocular pain, and rash. These cases of Mayaro fever are likely to represent the tip of an iceberg, and probably a much greater number of cases occurred in Manaus in the study period.

Identification of Oropouche Orthobunyavirus in the cerebrospinal fluid of three patients in the Amazonas, Brazil.

Oropouche fever is the second most frequent arboviral infection in Brazil, surpassed only by dengue. Oropouche virus (OROV) causes large and explosive outbreaks of acute febrile illness in cities and villages in the Amazon and Central-Plateau regions. Cerebrospinal fluid (CSF) samples from 110 meningoencephalitis patients were analyzed. The RNA extracted from fluid was submitted to reverse transcription-polymerase chain reaction and sequencing to identify OROV. Three CSF samples showed the presence of OROV causing infection in the central nervous system (CNS). These patients are adults. Two of the patients had other diseases affecting CNS and immune systems: neurocysticercosis and acquired immunodeficiency syndrome, respectively. Nucleotide sequence analysis showed that the OROV from the CSF of these patients belonged to genotype I. We show here that severe Oropouche disease is occurring during outbreaks of this virus in Brazil.

Oropouche fever outbreak, Manaus, Brazil, 2007-2008.

To the Editor: Oropouche virus (OROV) is an arbovirus, Orthobunyavirus, transmitted among sloths, marsupials, primates, and birds by the mosquitoes Aedes serratus and Culex quinquefasciatus. Notably, this virus has adapted to an urban cycle involving man, with midges (Culicoides paraensis) as the main vector (1). Oropouche fever is the second most frequent arboviral disease in Brazil, surpassed only by dengue. OROV causes large, explosive outbreaks of acute febrile illness in cities and villages in the Amazon and central regions of Brazil. An estimated 500,000 cases of OROV infection have occurred in Brazil in the past 48 years. In addition to outbreaks, OROV can also cause sporadic human infections (2). The Tropical Medicine Foundation of Amazonas State (TMF-AM) is a tertiary care center specializing in tropical and infectious diseases and is located in the city of Manaus. Syndromic surveillance for acute febrile illness has been conducted by TMF-AM since 1998. During January 2007 through November 2008, we obtained blood samples from 631 patients who had acute febrile illness for ≥5 days but who had negative results at initial screening for malaria (thick blood smear) and dengue (MAC-ELISA). Blood samples were tested for OROV immunoglobulin (Ig) M antibodies by an indirect enzyme immune assay using infected cells as antigen, as previously reported for dengue (3). For the indirect enzyme immune assay using infected cells as antigen, C6/36 A. albopictus cells were grown in 96 well microplates; these cells were infected with OROV (BeAn 1991 strain). After 4 days, the cells were fixed in the wells with 7% formalin buffered at pH 7.0. The microplate was blocked with 5% skim milk and, after washing the wells, 100 µL of serum diluted 1:400 was added into infected and uninfected wells. After incubation and washing the wells, a peroxidase-conjugated goat anti-human IgM was added; finally, the ABTS substrate (KPL, Inc., Gaithersburg, MD, USA) was added into the wells. The plates were incubated and read on a spectrophotometer at 405 nm. The cutoff for the test was determined to be the mean of optical densities read in all wells containing uninfected cells plus 3 standard deviations. Of the 631 patients in the study, 128 (20.3%) had IgM antibodies to OROV. The age range was 2–81 years (mean 29.5 ± 14 years), and 77 (60.2%) were women or girls. Most of the cases occurred November through March during the rainy season. In addition to fever, the patients had headache (93 [72.7%]), myalgia (90 [70.3%]), and arthralgia (74 [57.8%]). Rash was observed in 54 patients (42.2%), and hemorrhagic phenomena (petechiae, epistaxis, and gingival bleeding) were observed in 20 patients (15.5%). All patients recovered without sequelae and were not hospitalized. Despite the knowledge of the occurrence of several arboviruses in the Amazon region, most cases of arboviral diseases remain undiagnosed, probably because of their generally mild and self-limited clinical manifestations. Patients usually recover completely after a couple of days. However, even more severe cases may remain undiagnosed, especially because of long distances to health care facilities, difficulties in sample transportation, and lack of laboratory facilities capable of conducting the diagnostic assays. With regard to OROV infections, diagnosis of OROV may be easily confused with other acute febrile illness, including malaria and dengue, both of which are highly endemic in Manaus. In the present study, an inhouse enzyme immune assay for IgM using infected cell culture as antigen was found suitable for the diagnosis of OROV infections in the acute phase. Thus, a combination of a systematic surveillance for acute febrile illnesses and efficient laboratory diagnosis for OROV resulted in the discovery of an outbreak, which would probably have been overlooked if it had occurred in any region simultaneously with large dengue outbreaks or in the absence of laboratory diagnosis. The cases of OROV fever reported here likely represent a small portion of the cases; a much higher number of cases probably occurred in Manaus during the study period. The clinical characteristics of most cases of OROV fever in this outbreak were similar to previously reported descriptions of the illness. Notably, however, 20 (15.5%) patients from Manaus had spontaneous hemorrhagic phenomena (petecchiae, epistaxis, and gingival bleeding) that had not previously been described in OROV fever (4–6). Moreover, symptoms of involvement of the central nervous system were not observed. In recent years, the area of circulation and the epidemic potential of OROV have increased, and this virus has emerged as a public health problem in Brazil and other countries in the Americas. Presently, OROV is the most common of the Brazilian zoonotic arboviruses infecting humans (7). Further evidence of the spread of OROV was its isolation in 2003 from a small primate, a marmoset (Callithrix), in the state of Minas Gerais in southeast Brazil, far from the Amazon region (8). Considering that midges (Culicoides paraensis) occur in most low altitude areas of the Americas, it is conceivable that environmental destruction and climate changes could result in OROV outbreaks in the large cities of Brazil, as well as in other parts of the Western Hemisphere (9).

Severe Rhabdomyolysis Caused by Plasmodium vivax Malaria in the Brazilian Amazon

Severe rhabdomyolysis (creatine phosphokinase = 29,400 U/L) developed in a 16-year-old boy from Manaus, Brazil, after he started treatment with chloroquine for infection with Plasmodium vivax. Treatment led to myoglobinuria and acute renal failure. After hemodialysis, the patient improved and a muscle biopsy specimen showed no myophosphorylase or deaminase deficiency. This case of rhabdomyolysis associated with P. vivax infection showed no comorbidities. The pathogenesis is still unclear. Although rhabdomyolysis is generally reported as a complication of Plasmodium falciparum malaria, leading to metabolic and renal complications,1 it has been reported in a patient with P. vivax infection with myoadenylate deaminase deficiency.2 We report a case in a patient without typical muscle enzyme deficiencies in which severe rhabdomyolysis developed while the patients was being treated with chloroquine for a confirmed P. vivax infection.

Simultaneous circulation of all four dengue serotypes in Manaus, State of Amazonas, Brazil in 2011

INTRODUCTION Manaus, the capital city of the state of Amazon with nearly 2 million inhabitants, is located in the middle of the Amazon rain forest and has suffered dengue outbreaks since 1998. METHODS In this study, blood samples were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), aimed at identifying dengue virus serotypes. RESULTS Acute phase sera from 432 patients were tested for the presence of dengue virus. Out of the 432 patients, 137 (31.3%) were found to be positive. All the four dengue virus serotypes were observed. CONCLUSIONS The simultaneous circulation of the four dengue serotypes is described for the first time in Manaus and in Brazil.

Co-infection of Dengue virus by serotypes 3 and 4 in patients from Amazonas, Brazil

The natural co-infection with dengue virus can occur in highly endemic areas where different serotypes have been observed for many years. We report here four cases of DENV-3/DENV-4 co-infection detected by serological and molecular tests among 674 patients with acute undifferentiated fever from the tropical medicine reference center of Manaus City, Brazil, between 2005 and 2010. Analysis of the sequences obtained indicated the presence of genotype 3 and 1 for DENV-3 and DENV-4 respectively.

P. vivax malaria and dengue fever co-infection: a cross-sectional study in the Brazilian Amazon.

Background Malaria and dengue are the most prevalent vector-borne diseases worldwide and represent major public health problems. Both are endemic in tropical regions, propitiating co-infection. Only few co-infection cases have been reported around the world, with insufficient data so far to enhance the understanding of the effects of co-infection in the clinical presentation and severity. Methodology/Principal Findings A cross-sectional study was conducted (2009 to 2011) in hospitalized patients with acute febrile syndrome in the Brazilian Amazon. All patients were submitted to thick blood smear and PCR for Plasmodium sp. detection, ELISA, PCR and NS1 tests for dengue, viral hepatitis, HIV and leptospirosis. In total, 1,578 patients were recruited. Among them, 176 (11.1%) presented P. vivax malaria mono-infection, 584 (37%) dengue fever mono-infection, and 44 (2.8%) were co-infected. Co-infected patients had a higher chance of presenting severe disease (vs. dengue mono-infected), deep bleeding (vs. P. vivax mono-infected), hepatomegaly, and jaundice (vs. dengue mono-infected). Conclusions/Significance In endemic areas for dengue and malaria, jaundice (in dengue patients) and spontaneous bleeding (in malaria patients) should raise the suspicion of co-infection. Besides, whenever co-infection is confirmed, we recommend careful monitoring for bleeding and hepatic complications, which may result in a higher chance of severity, despite of the fact that no increased fatality rate was seen in this group.