Mayaro virus is endemic in South America and sporadic outbreaks have been described. It causes a dengue-like febrile illness accompanied by severe and long-lasting polyarthralgias. Outside endemic regions, however, the disease is not well known and can be misdiagnosed as dengue. International travellers are at risk to acquire Mayaro virus and due to increased worldwide travel infectious disease specialists need to be aware of such rare clinical entities.
We report the first Mayaro virus infection imported into Germany. A 20-year-old woman developed fever, myalgia, maculopapular rash, and polyarthralgias following a 10-day trip in the Rurrenabaque region of Bolivia. Severe polyarthralgias persisted for 5 months and were treated with non-steroidal anti-inflammatory drugs. Serological analysis demonstrated Mayaro virus-specific-IgM and -IgG antibodies two months after onset of symptoms. Except for CXCL8/IL-8 other proinflammatory chemokines and cytokines were unremarkable at this time.
Dissemination of knowledge on rare disease might improve patient management. Understanding the inherent features of Mayaro virus infection and how the virus interacts with its host are essential for optimal patient care and therapy.
Mayaro virus; Alphavirus; Persistent arthralgia; Inflammatory cytokines
West Nile virus; arbovirus; Germany; serology; viruses; vector-borne infections
This study aimed to identify the causative agent of mass mortality in wild and captive birds in southwest Germany and to gather insights into the phylogenetic relationship and spatial distribution of the pathogen. Since June 2011, 223 dead birds were collected and tested for the presence of viral pathogens. Usutu virus (USUV) RNA was detected by real-time RT-PCR in 86 birds representing 6 species. The virus was isolated in cell culture from the heart of 18 Blackbirds (Turdus merula). USUV-specific antigen was demonstrated by immunohistochemistry in brain, heart, liver, and lung of infected Blackbirds. The complete polyprotein coding sequence was obtained by deep sequencing of liver and spleen samples of a dead Blackbird from Mannheim (BH65/11-02-03). Phylogenetic analysis of the German USUV strain BH65/11-02-03 revealed a close relationship with strain Vienna that caused mass mortality among birds in Austria in 2001. Wild birds from lowland river valleys in southwest Germany were mainly affected by USUV, but also birds kept in aviaries. Our data suggest that after the initial detection of USUV in German mosquitoes in 2010, the virus spread in 2011 and caused epizootics among wild and captive birds in southwest Germany. The data also indicate an increased risk of USUV infections in humans in Germany.
Clinical arbovirus screening requires exclusion of a broad range of viruses with as few assays as possible. We present a reverse transcription-PCR (RT-PCR) for the detection of all species of the genus Alphavirus qualified for exclusion screening (limit of detection [LOD], 5 to 100 RNA copies per reaction across all Alphavirus species; detection of viremia down to ca. 10,000 copies per ml).
The method of choice for the detection of Lassa virus is reverse transcription (RT)-PCR. However, the high degree of genetic variability of the virus poses a problem with the design of RT-PCR assays that will reliably detect all strains. Recently, we encountered difficulties in detecting some strains from Liberia and Nigeria in a commonly used glycoprotein precursor (GPC) gene-specific RT-PCR assay (A. H. Demby, J. Chamberlain, D. W. Brown, and C. S. Clegg, J. Clin. Microbiol. 32:2898-2903, 1994), which prompted us to revise the protocol. The design of the new assay, the GPC RT-PCR/2007 assay, took into account 62 S RNA sequences from all countries where Lassa fever is endemic, including 40 sequences generated from the strains in our collection. The analytical sensitivity of the new assay was determined with 11 strains from Sierra Leone, Liberia, Ivory Coast, and Nigeria by probit analysis; the viral loads detectable with a probability of 95% ranged from 342 to 2,560 S RNA copies/ml serum, which corresponds to 4 to 30 S RNA copies/assay. The GPC RT-PCR/2007 assay was validated with 77 serum samples and 1 cerebrospinal fluid sample from patients with laboratory-confirmed Lassa fever. The samples mainly originated from Liberia and Nigeria and included strains difficult to detect in the assay of 1994. The GPC RT-PCR/2007 assay detected virus in all clinical specimens (100% sensitivity). In conclusion, a new RT-PCR assay, based in part on the protocol developed by Demby et al. in 1994, for the detection of Lassa virus is described. Compared to the assay developed in 1994, the GPC RT-PCR/2007 assay offers improved sensitivity for the detection of Liberian and Nigerian Lassa virus strains.
Ebolaviruses (EBOV) (family Filoviridae) cause viral hemorrhagic fevers in humans and non-human primates when they spill over from their wildlife reservoir hosts with case fatality rates of up to 90%. Fruit bats may act as reservoirs of the Filoviridae. The migratory fruit bat, Eidolon helvum, is common across sub-Saharan Africa and lives in large colonies, often situated in cities. We screened sera from 262 E. helvum using indirect fluorescent tests for antibodies against EBOV subtype Zaire. We detected a seropositive bat from Accra, Ghana, and confirmed this using western blot analysis. The bat was also seropositive for Lagos bat virus, a Lyssavirus, by virus neutralization test. The bat was fitted with a radio transmitter and was last detected in Accra 13 months after release post-sampling, demonstrating long-term survival. Antibodies to filoviruses have not been previously demonstrated in E. helvum. Radio-telemetry data demonstrates long-term survival of an individual bat following exposure to viruses of families that can be highly pathogenic to other mammal species. Because E. helvum typically lives in large urban colonies and is a source of bushmeat in some regions, further studies should determine if this species forms a reservoir for EBOV from which spillover infections into the human population may occur.
Lassa fever; Liberia; laboratory diagnosis; reverse transcription–PCR; viruses; sensitivity; letter
Adventure tourism may bring this disease to Western countries.
On July 10, 2008, Marburg hemorrhagic fever was confirmed in a Dutch patient who had vacationed recently in Uganda. Exposure most likely occurred in the Python Cave (Maramagambo Forest), which harbors bat species that elsewhere in Africa have been found positive for Marburg virus. A multidisciplinary response team was convened to perform a structured risk assessment, perform risk classification of contacts, issue guidelines for follow-up, provide information, and monitor the crisis response. In total, 130 contacts were identified (66 classified as high risk and 64 as low risk) and monitored for 21 days after their last possible exposure. The case raised questions specific to international travel, postexposure prophylaxis for Marburg virus, and laboratory testing of contacts with fever. We present lessons learned and results of the follow-up serosurvey of contacts and focus on factors that prevented overreaction during an event with a high public health impact.
Marburg virus diseases; hemorrhagic fever; exposure; contacts; temperature monitoring; filovirus; viruses; perspective
Chikungunya fever should be added to the list of differential diagnoses for ill travelers returning from this region.
Chikungunya fever has spread through several Indian Ocean islands and India, including popular travel destinations. To compare usefulness of diagnostic tests and to understand reasons for the magnitude and severity of an outbreak, we used 3 diagnostic methods to test 720 samples from 680 patients returning to Europe from the Indian Ocean region in 2006. Chikungunya infection was confirmed for 24.4% patients in the first half of the year and for 9.9% in the second half. Reverse transcription–PCR was positive for all samples taken up to day 4 after symptom onset. Immunofluorescence detected immunoglobulin (Ig) M on day 1 and IgG on day 2 for some patients, and in all patients from day 5 onward. Soon after onset of symptoms, patients had IgG and IgM and high viral loads (some >109 copies/mL plasma). These data will help healthcare providers select diagnostic tests for returning travelers.
chikungunya; travelers; dengue; arbovirus diagnostics; real-time RT-PCR; serology; research
In Europe, hemorrhagic fever with renal syndrome results mainly from infection with Puumala virus (PUUV) or Dobrava virus. For 31 patients from a hantavirus disease outbreak in Lower Bavaria, a district in southeast Germany, serodiagnosis was undertaken by enzyme-linked immunosorbent assay, immunofluorescence assay, and immunoblot analysis. In a few of these cases, however, PUUV-specific typing of antibodies by these standard assays failed and a virus neutralization assay under biosafety level 3 conditions was required to verify the infection by this virus type. PUUV RNA was amplified by reverse transcription-PCR from acute-phase sera of three patients and was found to be very closely related to virus sequences obtained from bank voles (Clethrionomys glareolus) trapped in the same area. These findings link the outbreak with a novel PUUV lineage, “Bavaria,” circulating in the local rodent population. The Bavaria lineage associated with the outbreak is only distantly related to other PUUV lineages from Germany.
Lassa fever; Nigeria; arenavirus; letter
First-generation reverse transcription-PCR (RT-PCR) assays for severe acute respiratory syndrome-associated coronavirus (SARS-CoV) gave false-negative results in a considerable fraction of patients. In the present study, we evaluated two second-generation, replicase (R) gene-based, real-time RT-PCR test kits—the RealArt HPA coronavirus LC kit (Artus, Hamburg, Germany) and the LightCycler SARS-CoV quantification kit (Roche, Penzberg, Germany)—and a real-time RT-PCR assay for the nucleocapsid (N) gene. Detecting the N-gene RNA might be advantageous due to its high abundance in cells. The kits achieved sensitivities of 70.8% (Artus) and 67.1% (Roche) in 66 specimens from patients with confirmed SARS (samples primarily from the upper and lower respiratory tract and stool). The sensitivity of the N-gene assay was 74.2%. The differences in all of the sensitivities were not statistically significant (P = 0.680 [analysis of variance]). Culture cells initially contained five times more N- than R-gene RNA, but the respective levels converged during 4 days of virus replication. In clinical samples the median concentrations of R- and N-gene RNA, respectively, were 1.2 × 106 and 2.8 × 106 copies/ml (sputum and endotracheal aspirates), 4.3 × 104 and 5.5 × 104 copies/ml (stool), and 5.5 × 102 and 5.2 × 102 copies/sample (throat swabs and saliva). Differences between the samples types were significant but not between the types of target RNA. All (n = 12) samples from the lower respiratory tract tested positive in all tests. In conclusion, the novel assays are more sensitive than the first-generation tests, but they still do not allow a comprehensive ruling out of SARS. Methods for the routine sampling of sputum without infection risk are needed to improve SARS RT-PCR.
Seven outbreaks of disease characterized by a pustular rash and suspected to have been caused by human monkeypox virus were investigated. The outbreaks occurred between February and August 2001 in the province of Equateur in the Democratic Republic of Congo. The outbreaks involved a total of 31 persons and caused five deaths. Specimens from 14 patients were available and were analyzed by electron microscopy, virus isolation, and PCR assays specific for monkeypox virus and varicella-zoster virus. We provide evidence that two outbreaks were indeed caused by monkeypox virus (16 cases, with four deaths), that in two outbreaks both monkeypox and varicella-zoster virus were involved (seven cases, with one death), and that two outbreaks were cases of chickenpox caused by infection with varicella-zoster virus (six cases, with no deaths). In one outbreak, no evidence for either monkeypox or chickenpox was found (two cases, with no deaths).
In consecutive serum samples from 25 tourists with acute dengue fever, virus-specific RNA was detected by using fully automated TaqMan reverse transcriptase PCR. For this amplification technique new primers and special fluorochrome-labeled probes had to be synthesized. During amplification the increasing amount of viral DNA could simultaneously be measured in the tightly sealed tubes. Dengue virus RNA was found in almost all patients (17 of 18), if the samples had been taken soon after the onset of symptoms and before anti-dengue virus antibody had been produced. RNA was detectable in only one of five persons who had anti-dengue virus immunoglobulin M (IgM) antibodies but not yet IgG antibodies. In 30 late samples with both IgG and IgM antibodies viral RNA was no longer demonstrable. In two early samples from two frequent travelers obtained 1 and 2 days after the onset of symptoms significant IgG antibody titers were present but there were no anti-dengue virus IgM antibodies. In these samples a viral load of >5 × 106 dengue virus RNA copies (dengue types 1 and 2) was detectable. These findings of a high viral load in the presence of anti-dengue virus IgG antibody are suggestive of a secondary dengue virus infection. In the 20 tourists (17 plus 1 plus 2) in whom viral RNA was found, the dengue virus serotype could be related to the area where the infection had taken place. Most of our patients came from southeast Asia and most frequently had dengue virus type 1 infections (8 of 20).