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Zika virus is a flavivirus known to cause human infection in Asia and Africa. This article describes an outbreak of Zika virus infection on Yap Island, Federated States of Micronesia, with predominant symptoms of rash, fever, arthralgia, and conjunctivitis. An estimated 73% of Yap residents 3 years of age or older became infected during the 4 months of the outbreak. This article describes an outbreak of Zika virus infection on Yap Island, Federated States of Micronesia, with predominant symptoms of rash, fever, arthralgia, and conjunctivitis. An estimated 73% of Yap residents 3 years of age or older became infected. Zika virus is a flavivirus (family Flaviviridae) related to West Nile, dengue, and yellow fever viruses. 1 Zika virus was isolated in 1947 from a rhesus monkey in the Zika forest near Entebbe, Uganda 2 ; its genome was sequenced in 2006. 3 There is serologic evidence of human Zika virus infection in Africa and Asia, and the virus has been isolated from humans in Uganda, Nigeria, and Senegal. 2 – 12 Zika virus is believed to be transmitted to humans by infected mosquitoes and has been isolated from Aedes africanus, Aedes luteocephalus, and Aedes aegypti . 13 – 16 No outbreaks and only 14 cases of . . .

An inexpensive live attenuated vaccine (the 17D vaccine) against yellow fever has been effectively used to prevent yellow fever for more than 70 years. Interest in developing new inactivated vaccines has been spurred by recognition of rare but serious, sometimes fatal adverse events following live virus vaccination. A safer inactivated yellow fever vaccine could be useful for vaccinating people at higher risk of adverse events from the live vaccine, but could also have broader global health utility by lowering the risk-benefit threshold for assuring high levels of yellow fever vaccine coverage. If ongoing trials demonstrate favorable immunogenicity and safety compared to the current vaccine, the practical global health utility of an inactivated vaccine is likely to be determined mostly by cost.

Background. Most West Nile virus (WNV) infections in humans are asymptomatic; severe disease occurs in relatively few patients and typically manifests as encephalitis, meningitis, or acute flaccid paralysis. A few cases of life-threatening disease with diffuse hemorrhagic manifestations have been reported in Africa; however, this clinical presentation has not been documented for any of the >16,700 cases of WNV disease reported in the United States during 1999–2004. We describe a case of fulminant WNV infection in a 59-year-old Florida man who died following a brief illness that resembled hemorrhagic disease caused by Rickettsia rickettsii, dengue virus or yellow fever virus. Methods. Traditional and contemporary diagnostic assays, including culture isolation, electron microscopic examination, reverse-transcriptase polymerase chain reaction amplification, and immunohistochemical stains, were used to confirm systemic WNV infection in the patient. Results. WNV was isolated in a cell culture from a skin biopsy specimen obtained from the patient shortly prior to death. Electron microscopic examination identified the isolate as a flavivirus, and reverse-transcriptase polymerase chain reaction amplified specific WNV sequences from the isolate and patient tissue. Quantitative polymerase chain reaction identified approximately 1 × 107 viral copies/mL in the patient's serum. WNV antigens were detected by immunohistochemical stains in intravascular mononuclear cells and endothelium in skin, lung, liver, kidney, spleen, bone marrow, and central nervous system; no viral antigens were identified in neurons or glial cells of the central nervous system. Conclusions. Although hemorrhagic disease is a rare manifestation of WNV infection, the findings provided by this report may offer new insights regarding the clinical spectrum and pathogenesis of WNV disease in humans.

More than 75,000 cases of Lyme disease are reported each year in Europe and the United States. Prophylactic treatment after tick bites is only one part of a plan for primary prevention. Other strategies include checking for ticks, use of acaricides, management of vegetation, use of repellents, and techniques to reduce deer and rodent populations. Reducing tick populations can help prevent all tick-borne illnesses. Treatment after tick bites is only one part of primary prevention. The number of cases of Lyme disease reported in the United States has increased from 491 cases in 1982, 1 the first year of national surveillance, to 17,029 in 2001, 2 despite federal, state, and local efforts to prevent the disease. About 60,000 cases are reported each year in Europe. 3 Most efforts at prevention have focused on spreading information about how Lyme disease is transmitted and on encouraging people to use repellents, wear protective clothing, and check themselves for ticks. These strategies are inexpensive and unlikely to be harmful, but their effectiveness has not been conclusively demonstrated. It is possible that these . . .

Yellow fever (YF) vaccine has been used for prevention of YF since 1937 with over 500 million doses administered. However, rare reports of severe adverse events following vaccination have raised concerns about the vaccine’s safety. We reviewed reports of adverse events following YF vaccination reported to the U.S. Vaccine Adverse Event Reporting System (VAERS) from 2000 to 2006. We used estimates of age and sex distribution of administered doses obtained from a 2006 survey of authorized vaccine providers to calculate age- and sex-specific reporting rates of all serious adverse events (SAE), anaphylaxis, YF vaccine-associated neurotropic disease, and YF vaccine-associated viscerotropic disease. Reporting rates of SAEs were substantially higher in males and in persons aged ≥60 years. These findings reinforce the generally acceptable safety profile of YF vaccine, but highlight the importance of physician and traveler education regarding the risks and benefits of YF vaccination, particularly for travelers ≥60 years of age. Vaccination should be limited to persons traveling to areas where the risk of YF is expected to exceed the risk of serious adverse events after vaccination, or if not medically contraindicated, where national regulations require proof of vaccination to prevent introduction of YF.

•The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) evaluates vaccine safety.•Many recombinant viral vectored vaccines are in advanced clinical trials.•A template is presented for evaluating live recombinant flavivirus vaccines in which genes for envelope proteins have replaced the corresponding genes in yellow fever virus vaccine.•The template can be used as a model for other live recombinant viral vaccines. The Brighton Collaboration Viral Vector Vaccines Safety Working Group (V3SWG) was formed to evaluate the safety of live, recombinant viral vaccines incorporating genes from heterologous viruses inserted into the backbone of another virus (so-called “chimeric virus vaccines”). Many viral vector vaccines are in advanced clinical trials. The first such vaccine to be approved for marketing (to date in Australia, Thailand, Malaysia, and the Philippines) is a vaccine against the flavivirus, Japanese encephalitis (JE), which employs a licensed vaccine (yellow fever 17D) as a vector. In this vaccine, two envelope proteins (prM-E) of YF 17D virus were exchanged for the corresponding genes of JE virus, with additional attenuating mutations incorporated into the JE gene inserts. Similar vaccines have been constructed by inserting prM-E genes of dengue and West Nile into YF 17D virus and are in late stage clinical studies. The dengue vaccine is, however, more complex in that it requires a mixture of four live vectors each expressing one of the four dengue serotypes. This vaccine has been evaluated in multiple clinical trials. No significant safety concerns have been found. The Phase 3 trials met their endpoints in terms of overall reduction of confirmed dengue fever, and, most importantly a significant reduction in severe dengue and hospitalization due to dengue. However, based on results that have been published so far, efficacy in preventing serotype 2 infection is less than that for the other three serotypes. In the development of these chimeric vaccines, an important series of comparative studies of safety and efficacy were made using the parental YF 17D vaccine virus as a benchmark. In this paper, we use a standardized template describing the key characteristics of the novel flavivirus vaccine vectors, in comparison to the parental YF 17D vaccine. The template facilitates scientific discourse among key stakeholders by increasing the transparency and comparability of information. The Brighton Collaboration V3SWG template may also be useful as a guide to the evaluation of other recombinant viral vector vaccines.

Background Rotavirus is the most common cause of severe gastroenteritis among young children in Spain and worldwide. We evaluated hospitalizations due to community and hospital-acquired rotavirus gastroenteritis (RVGE) and estimated related costs in children under 5 years old in Catalonia, Spain. Results We analyzed hospital discharge data from the Catalan Health Services regarding hospital admissions coded as infectious gastroenteritis in children under 5 for the period 2003-2008. In order to estimate admission incidence, we used population estimates for each study year published by the Statistic Institut of Catalonia (Idescat). The costs associated with hospital admissions due to rotavirus diarrhea were estimated for the same years. A decision tree model was used to estimate the threshold cost of rotavirus vaccine to achieve cost savings from the healthcare system perspective in Catalonia. From 2003 through 2008, 10655 children under 5 years old were admitted with infectious gastroenteritis (IGE). Twenty-two percent of these admissions were coded as RVGE, yielding an estimated average annual incidence of 104 RVGE hospitalizations per 100000 children in Catalonia. Eighty seven percent of admissions for RVGE occurred during December through March. The mean hospital stay was 3.7 days, 0.6 days longer than for other IGE. An additional 892 cases of presumed nosocomial RVGE were detected, yielding an incidence of 2.5 cases per 1000 child admissions. Total rotavirus hospitalization costs due to community acquired RVGE for the years 2003 and 2008 were 431,593 and 809,224 €, respectively. According to the estimated incidence and hospitalization costs, immunization would result in health system cost savings if the cost of the vaccine was 1.93 € or less. At a vaccine cost of 187 € the incremental cost per hospitalization prevented is 195,388 € (CI 95% 159,300; 238,400). Conclusions The burden of hospitalizations attributable to rotavirus appeared to be lower in Catalonia than in other regions of Spain and Europe. The relatively low incidence of hospitalization due to rotavirus makes rotavirus vaccination less cost-effective in Catalonia than in other areas with higher rotavirus disease burden.

In the summer of 1999, West Nile virus was recognised in the western hemisphere for the first time when it caused an epidemic of encephalitis and meningitis in the metropolitan area of New York City, NY, USA. Intensive hospital-based surveillance identified 59 cases, including seven deaths in the region. We did a household-based seroepidemiological survey to assess more clearly the publichealth impact of the epidemic, its range of illness, and risk factors associated with infection. We used cluster sampling to select a representative sample of households in an area of about 7·3 km2 at the outbreak epicentre. All individuals aged 5 years or older were eligible for interviews and phlebotomy. Serum samples were tested for IgM and IgG antibodies specific for West Nile virus. 677 individuals from 459 households participated. 19 were seropositive (weighted seroprevalence 2·6% [95% CI 1·2–4·1). Six (32%) of the seropositive individuals reported a recent febrile illness compared with 70 of 648 (11%) seronegative participants (difference 21% [0–47]). A febrile syndrome with fatigue, headache, myalgia, and arthralgia was highly associated with seropositivity (prevalence ratio 7·4 [1·5–36·6]). By extrapolation from the 59 diagnosed meningoencephalitis cases, we conservatively estimated that the New York outbreak consisted of 8200 (range 3500–13 000) West Nile viral infections, including about 1700 febrile infections. During the 1999 West Nile virus outbreak, thousands of symptomless and symptomatic West Nile viral infections probably occurred, with fewer than 1% resulting in severe neurological disease.

Yellow fever (YF), can be prevented by an attenuated vaccine (YEL). We reviewed neurologic adverse events (AE) following YEL that were reported to the national Vaccine Adverse Events Reporting System (VAERS). VAERS is a passive reporting system with inherent limitations for causality assessment. Based on defined criteria, five cases of encephalitis were classified as ‘definitely’ and one of acute disseminated encephalomyelitis (ADEM) as ‘probably’ caused by YEL. Six cases of Guillain-Barre Syndrome (GBS), one of encephalitis, and two of ADEM, were classified as ‘suspect’ vaccine-associated disease. Laboratory and epidemiological evidence suggests that YEL caused encephalitis. Additional studies will be required to confirm whether YEL can rarely result in GBS and/or ADEM.

After its surprising detection in New York City in 1999, West Nile virus became a major clinical and public health concern in North America. Drs. Lyle R. Petersen and Edward B. Hayes write about the dramatic westward spread of West Nile virus. West Nile virus, a mosquito-borne flavivirus, was first isolated from a febrile patient in the West Nile region of Uganda in 1937. For the next 60 years, it remained a little-understood cause of febrile illness and sporadic encephalitis in parts of Africa, Europe, and Asia, garnering scant medical attention. After its surprising detection in New York City in 1999, West Nile virus became a major clinical and public health concern in North America. The next year, the Centers for Disease Control and Prevention collaborated with state and local health departments to establish ArboNet, an electronic surveillance system for tracking West . . .