Changjun Bao

Probable limited person-to-person transmission of highly pathogenic avian influenza A (H5N1) virus in China.

BACKGROUND In December, 2007, a family cluster of two individuals infected with highly pathogenic avian influenza A (H5N1) virus was identified in Jiangsu Province, China. Field and laboratory investigations were implemented immediately by public-health authorities. METHODS Epidemiological, clinical, and virological data were collected and analysed. Respiratory specimens from the patients were tested by reverse transcriptase (RT) PCR and by viral culture for the presence of H5N1 virus. Contacts of cases were monitored for symptoms of illness for 10 days. Any contacts who became ill had respiratory specimens collected for H5N1 testing by RT PCR. Sera were obtained from contacts for H5N1 serological testing by microneutralisation and horse red-blood-cell haemagglutinin inhibition assays. FINDINGS The 24-year-old index case died, and the second case, his 52-year-old father, survived after receiving early antiviral treatment and post-vaccination plasma from a participant in an H5N1 vaccine trial. The index cases only plausible exposure to H5N1 virus was a poultry market visit 6 days before the onset of illness. The second case had substantial unprotected close exposure to his ill son. 91 contacts with close exposure to one or both cases without adequate protective equipment provided consent for serological investigation. Of these individuals, 78 (86%) received oseltamivir chemoprophylaxis and two had mild illness. Both ill contacts tested negative for H5N1 by RT PCR. All 91 close contacts tested negative for H5N1 antibodies. H5N1 viruses isolated from the two cases were genetically identical except for one non-synonymous nucleotide substitution. INTERPRETATION Limited, non-sustained person-to-person transmission of H5N1 virus probably occurred in this family cluster.

Probable person to person transmission of novel avian influenza A (H7N9) virus in Eastern China, 2013: epidemiological investigation

Objective To determine whether the novel avian influenza H7N9 virus can transmit from person to person and its efficiency. Design Epidemiological investigations conducted after a family cluster of two patients with avian H7N9 in March 2013. Setting Wuxi, Eastern China. Participants Two patients, their close contacts, and relevant environments. Samples from the patients and environments were collected and tested by real time reverse transcriptase-polymerase chain reaction (rRT-PCR), viral culture, and haemagglutination inhibition assay. Any contacts who became ill had samples tested for avian H7N9 by rRT-PCR. Paired serum samples were obtained from contacts for serological testing by haemagglutination inhibition assays. Main outcomes measures Clinical data, history of exposure before the onset of illnesses, and results of laboratory testing of pathogens and further analysis of sequences and phylogenetic tree to isolated strains. Results The index patient became ill five to six days after his last exposure to poultry. The second patient, his daughter aged 32, who provided unprotected bedside care in the hospital, had no known exposure to poultry. She developed symptoms six days after her last contact with her father. Two strains were isolated successfully from the two patients. Genome sequence and analyses of phylogenetic trees showed that both viruses were almost genetically identical. Forty three close contacts of both patients were identified. One had mild illness but had negative results for avian H7N9 by rRT-PCR. All 43 close contacts tested negative for haemagglutination inhibition antibodies specific for avian H7N9. Conclusions The infection of the daughter probably resulted from contact with her father (the index patient) during unprotected exposure, suggesting that in this cluster the virus was able to transmit from person to person. The transmissibility was limited and non-sustainable.

A Family Cluster of Infections by a Newly Recognized Bunyavirus in Eastern China, 2007: Further Evidence of Person-to-Person Transmission

BACKGROUND Seven persons in one family living in eastern China developed fever and thrombocytopenia during May 2007, but the initial investigation failed to identify an infectious etiology. In December 2009, a novel bunyavirus (designated severe fever with thrombocytopenia syndrome bunyavirus [SFTSV]) was identified as the cause of illness in patients with similar clinical manifestations in China. We reexamined this family cluster for SFTSV infection. METHODS We analyzed epidemiological and clinical data for the index patient and 6 secondary patients. We tested stored blood specimens from the 6 secondary patients using real time reverse transcription polymerase chain reaction (RT-PCR), viral culture, genetic sequencing, micro-neutralization assay (MNA), and indirect immunofluorescence assay (IFA). RESULTS An 80-year-old woman with fever, leucopenia, and thrombocytopenia died on 27 April 2007. Between 3 and 7 May 2007, another 6 patients from her family were admitted to a local county hospital with fever and other similar symptoms. Serum specimens collected in 2007 from these 6 patients were positive for SFTS viral RNA through RT-PCR and for antibody to SFTSV through MNA and IFA. SFTSV was isolated from 1 preserved serum specimen. The only shared characteristic between secondary patients was personal contact with the index patient; none reported exposure to suspected animals or vectors. CONCLUSIONS Clinical and laboratory evidence confirmed that the patients of fever and thrombocytopenia occurring in a family cluster in eastern China in 2007 were caused by a newly recognized bunyavirus, SFTSV. Epidemiological investigation strongly suggests that infection of secondary patients was transmitted to family members by personal contact.

Live-Animal Markets and Influenza A (H7N9) Virus Infection

A novel avian influenza A (H7N9) virus has shown the ability to infect humans. As described in this letter, human infection may be occurring because of multiple cross-species jumps from birds to humans.

Preparation and evaluation of recombinant severe fever with thrombocytopenia syndrome virus nucleocapsid protein for detection of total antibodies in human and animal sera by double-antigen sandwich enzyme-linked immunosorbent assay.

ABSTRACT The recent emergence of the human infection confirmed to be caused by severe fever with thrombocytopenia syndrome virus (SFTSV) in China is of global concern. Safe diagnostic immunoreagents for determination of human and animal seroprevalence in epidemiological investigations are urgently needed. This paper describes the cloning and expression of the nucleocapsid (N) protein of SFTSV. An N-protein-based double-antigen sandwich enzyme-linked immunosorbent assay (ELISA) system was set up to detect the total antibodies in human and animal sera. We reasoned that as the double-antigen sandwich ELISA detected total antibodies with a higher sensitivity than traditional indirect ELISA, it could be used to detect SFTSV-specific antibodies from different animal species. The serum neutralization test was used to validate the performance of this ELISA system. All human and animal sera that tested positive in the neutralization test were also positive in the sandwich ELISA, and there was a high correlation between serum neutralizing titers and ELISA readings. Cross-reactivity was evaluated, and the system was found to be highly specific to SFTSV; all hantavirus- and dengue virus-confirmed patient samples were negative. SFTSV-confirmed human and animal sera from both Anhui and Hubei Provinces in China reacted with N protein in this ELISA, suggesting no major antigenic variation between geographically disparate virus isolates and the suitability of this assay in nationwide application. ELISA results showed that 3.6% of the human serum samples and 47.7% of the animal field serum samples were positive for SFTSV antibodies, indicating that SFTSV has circulated widely in China. This assay, which is simple to operate, poses no biohazard risk, does not require sophisticated equipment, and can be used in disease surveillance programs, particularly in the screening of large numbers of samples from various animal species.

Cytokine and Chemokine Levels in Patients Infected with the Novel Avian Influenza A (H7N9) Virus in China

H7N9 avian influenza is an emerging viral disease in China caused by avian influenza A (H7N9) virus. We investigated host cytokine and chemokine profiles in serum samples of H7N9 patients by multiplex-microbead immunoassays. Statistical analysis showed that IP-10, IL-6, IL-17, and IL-2 were increased in H7N9 infected patients. Furthermore, IL-6 and the chemokine IP-10 were significantly higher in severe H7N9 patients compared to nonsevere H7N9 cases. We suggest that proinflammatory cytokine responses, characterized by a combined Th1/Th17 cytokine induction, are partially responsible for the disease progression of patients with H7N9 infection.

A novel bunyavirus in China.

To the Editor: Yu et al. (April 21 issue)1 report the emergence of an infectious disease in central China in the summer of 2009 that was identified as severe fever with thrombocytopenia syndrome (SFTS). Later that year the illness was found to be associated with infection with a novel bunya virus, designated SFTSV. According to Yu et al., at the time of publication there was no epidemiologic evidence of human-to-human transmission of the virus. We have identified a cluster of SFTSV infections in a family that appear to have been transmitted by means of human contact. On October 13, 2010, a 59-year-old man was admitted to a hospital in Nanjing, China, with a 1-week history of fever, gastrointestinal symptoms, leukopenia, and thrombocytopenia. According to laboratory tests, he also had an elevated aminotransferase level. The patient died in the hospital on October 21. On October 26, his son-inlaw reported the development of similar symptoms, but he recovered without sequelae. Real-time reverse-transcriptase–polymerase-chain-reaction (RT-PCR) assays of serum specimens from the two patients revealed the presence of SFTSV RNA, and SFTSV was isolated from each patient’s blood. The index patient had a son who never became ill, but specimens collected from the son showed immunologic evidence of recent infection. Enzymelinked immunosorbent assay (ELISA) performed on serum specimens collected on October 18 and 28 from the son did not detect the presence of IgM or IgG antibodies, but assays performed on November 18 and December 21 were positive for both antibodies. In addition, according to the results of indirect fluorescent-antibody and viral microneutralization testing, titers for IgG antibodies increased by a factor of 4 between October 18 and December 21. The index patient, who had three dogs and raised chickens, lived and worked in a wooded, hilly upland area dominated by shrubs and grasses. This environment was similar to that reported for the SFTSV-infected patients described by Yu et al., who determined that in these patients the virus was probably transmitted by ticks. Although the patient reported no history of tick bites, an ecologic survey identified SFTSV RNA in rodents and ticks near the house. However, it appears that his son and son-in-law became infected through their contact with the index patient. Unlike the index patient, the son and son-in-law had no obvious opportunity for contact with suspected vectors or hosts. They did not raise livestock and had no grass or low shrubs growing at the sites of their houses, and no rodents or ticks were caught inside or outside their houses. However, they did report having touched the bloody secretions and vomited blood of the index patient during his hospitalization. In addition, the timing of the son-in-law’s illness was highly compatible with contact transmission. After learning of his father-in-law’s illness, he drove to the hospital to provide bedside care (Fig. 1). Complete genomic sequencing showed that the viral strains isolated from the father and son-in-law were virtually identical (GenBank accession numbers, HQ830163 through HQ830168). Finally, the transmission of other viruses in the Bunyaviridae family between humans has been documented previously.2 The means of SFTSV transmission to the son and son-in-law is highly suggestive of person-toperson contact. This report highlights the need for enhanced surveillance, early diagnosis through laboratory testing, and strict infection control for suspected clinical viral hemorrhagic fever.3

Seroprevalence of antibodies against SFTS virus infection in farmers and animals, Jiangsu, China

BACKGROUND Severe fever with thrombocytopenia syndrome (SFTS) is a newly identified viral zoonosis caused by a phlebovirus. Most reported SFTS cases are farmers living in rural areas. The seroprevalence of SFTS virus in farmers has not been investigated. The current knowledge of SFTS virus seroprevalence in animals, especially in wild animals, is still poor. OBJECTIVES To investigate SFTS virus seroprevalence among farmers and a variety of animal species. STUDY DESIGN SFTS virus antibodies in sera were determined using a double-antigen sandwich ELISA. Serum samples were collected from 2547 farmers and 2741 animals in 6 SFTS-endemic counties from March 2012 to February 2013 in Jiangsu province. The farmer participants aged from 15 to 90 years. All of them were interviewed using a structured questionnaire. The animals sampled included 6 domesticated animal species and 2 wild animal species. RESULTS SFTSV antibodies were found in a total of 33 farmers (1.30%) and was more prevalent in males than in females (respectively 1.87% and 0.71%, P<0.01). The mean age of seropositive farmers was 56.5 years and seroprevalence increased gradually with age. Seroprevalence in animal species were: goats (66.8%), cattle (28.2%), dogs (7.4%), pigs (4.7%), chickens (1.2%), geese (1.7%), rodents (4.4%) and hedgehogs (2.7%). Multiple variable logistic regression analysis showed that grazing, grass mowing, raising cattle, age, farm work time and tick bites were risk factors for SFTS virus infection among farmers. CONCLUSIONS SFTSV readily infects humans with farming-related exposures as well as numerous domestic and wild animals. Serological results further suggest that the virus circulates widely in Jiangsu province.

Angiotensin II plasma levels are linked to disease severity and predict fatal outcomes in H7N9-infected patients

A novel influenza A (H7N9) virus of avian origin emerged in eastern China in the spring of 2013. This virus causes severe disease in humans, including acute and often lethal respiratory failure. As of January 2014, 275 cases of H7N9-infected patients had been reported, highlighting the urgency of identifying biomarkers for predicting disease severity and fatal outcomes. Here, we show that plasma levels of angiotensin II, a major regulatory peptide of the renin–angiotensin system, are markedly elevated in H7N9 patients and are associated with disease progression. Moreover, the sustained high levels of angiotensin II in these patients are strongly correlated with mortality. The predictive value of angiotensin II is higher than that of C-reactive protein and some clinical parameters such as the PaO2/FiO2 ratio (partial pressure of arterial oxygen to the fraction of inspired oxygen). Our findings indicate that angiotensin II is a biomarker for lethality in flu infections. Supplementary information The online version of this article (doi:10.1038/ncomms4595) contains supplementary material, which is available to authorized users.

Seroprevalence and Risk Factors for Severe Fever with Thrombocytopenia Syndrome Virus Infection in Jiangsu Province, China, 2011

Severe fever with thrombocytopenia syndrome (SFTS), which is caused by a novel bunyavirus, is an emerging infectious disease in China. In 2011, this new virus was designated as severe fever with thrombocytopenia syndrome virus (SFTSV). The aim of the present study was to determine the seroprevalence and risk factors of SFTSV infection. The investigation was conducted among the general population in Jiangsu Province, China in 2011. A total of 2,510 serum samples were collected. Testing by enzyme-linked immunosorbent assay was conducted to determine the seroprevalence of SFTSV infection. Result showed that the overall seroprevalence of SFTSV infection was 0.44% (11 of 2,510) in seven counties in Jiangsu Province. Multiple variable logistic regression analysis showed that raising goats, farming, and grazing were risk factors for SFTSV infection. Raising goats, farming, and grazing might be important risk factors for virus exposure, and appropriate health education could be useful in preventing infections.