SUMMARYThe recently established virus family Flaviviridae contains at least 68 recognized members. Sixty-six of these viruses were tested by cross-neutralization in cell cultures. Flaviviruses were separated into eight complexes [tick-borne encephalitis (12 viruses), Rio Bravo (six), Japanese encephalitis (10), Tyuleniy (three), Ntaya (five), Uganda S (four), dengue (four) and Modoc (five)] containing 49 viruses; 17 other viruses were not sufficiently related to warrant inclusion in any of these complexes.

An epidemic form of arthritis has been occurring in eastern Connecticut at least since 1972, with the peak incidence of new cases in the summer and early fall. Its identification has been possible because of tight geographic clustering in some areas, and because of a characteristic preceding skin lesion in some patients. The authors studied 51 residents of three contiguous Connecticut communities—39 children and 12 adults—who developed an illness characterized by recurrent attacks of asymmetric swelling and pain in a few large joints, especially the knee. Attacks were usually short (median: 1 week) with much longer intervening periods of complete remission (median: 2.5 months), but some attacks lasted for months. To date the typical patient has had three recurrences, but 16 patients have had none. A median of 4 weeks (range: 1–24) before the onset of arthritis, 13 patients (25%) noted an erythematous papule that developed into an expanding, red, annular lesion, as much as 50 cm in diameter. Only 2 of 159 family members of patients had such a lesion and did not develop arthritis (P < 0.000001). The overall prevalence of the arthritis was 4.3 cases per 1,000 residents, but the prevalence among children living on four roads was 1 in 10. Six families had more than 1 affected member. Nine of 20 symptomatic patients had low serum C3 levels, compared to none of 31 asymptomatic patients (P < 0.005); no patient had iridocyclitis or a positive test for antinuclear antibodies. Neither cultures of synovium and synovial fluid nor serologic tests were positive for agents known to cause arthritis. “Lyme arthritis” is thought to be a previously unrecognized clinical entity, the epidemiology of which suggests transmission by an arthropod vector.

The family Bunyaviridae comprises over 200 viruses (serotypes, subtypes, and varieties) that infect vertebrates and/or invertebrates. Four genera of viruses have been defined (Bunyavirus, Nairovirus, Phlebovirus, and Uukuvirus). The main characteristics of the member viruses are: (i) the virus particles are for the most part uniformly spherical, 80–110 nm in diameter, and possess a unit membrane envelope from which protrude polypeptide spikes 5–10 nm long; (ii) the viruses have three helical nucleocapsids, often in the form of supercoiled circles, each consisting of a single species of single-stranded RNA, a major nucleocapsid polypeptide, N, and at least in some cases minor amounts of a large polypeptide which may be a transcriptase component; (iii) the genome is composed of three species of RNA (L, large; M, medium; and S, small), organized in end-hydrogen bonded circular structures; (iv) most viruses have three major virion polypeptides (N, and two surface polypeptides, designated Gl and G2); (v) for at least some member viruses, the virions have been shown to contain an RNA-directed RNA polymerase, believed to be responsible for the synthesis of viral complementary mRNA, so that bunyaviruses are considered to be negative-stranded viruses; (vi) at least some bunyaviruses are capable of heterologous virus genome segment reassortment and can form recombinant viruses at high or low frequency; (vii) viruses appear to mature primarily at smooth membrane surfaces and accumulate in Golgi vesicles and saccules, or nearby; (viii) transovarial, venereal and/or transstadial transmission in arthropods has been shown to occur for some members of the family.

Abstract. Yellow fever (YF) is a significant health problem in South America and Africa. Travelers to these areas require immunization. The United States, infested with Aedes aegypti mosquitoes, is at risk of introduction of this disease. There is only a single U.S. manufacturer of YF 17D vaccine, and supplies may be insufficient in an emergency. A randomized, double-blind outpatient study was conducted in 1,440 healthy individuals, half of whom received the U.S. vaccine (YF-VAX) and half the vaccine manufactured in the United Kingdom (ARILVAX). A randomly selected subset of approximately 310 individuals in each treatment group was tested for YF neutralizing antibodies 30 days after vaccination. The primary efficacy endpoint was the proportion of individuals who developed a log neutralization index (LNI) of 0.7 or higher. Seroconversion occurred in 98.6% of individuals in the ARILVAX group and 99.3% of those in the YF-VAX group. Statistically, ARILVAX was equivalent to YF-VAX (P ‫ס‬ .001). Both vaccines elicited mean antibody responses well above the minimal level (LNI 0.7) protective against wild-type YF virus. The mean LNI in the YF-VAX group was higher (2.21) than in the ARILVAX group (2.06; P ‫ס‬ .010) possibly because of the higher dose contained in YF-VAX. Male gender, Caucasian race, and smoking were associated with higher antibody responses. Both vaccines were well tolerated. Overall, the treatment groups were comparable with respect to safety except that individuals in the ARILVAX group experienced significantly less edema, inflammation, and pain at the injection site than those in the YF-VAX group. No serious adverse events were attributable to either vaccine. YF-VAX participants (71.9%) experienced one or more nonserious adverse events than ARILVAX individuals (65.3%; P ‫ס‬ .008). The difference was due to a higher rate of injection site reactions in the YF-VAX group. Mild systemic reactions (headache, myalgia, malaise, asthenia) occurred in roughly 10% to 30% of participants during the first few days after vaccination, with no significant difference across treatment groups. Adverse events were less frequent in individuals with preexisting immunity to YF, indicating a relationship to virus replication.