Jamestown Canyon virus encephalitis in a heart transplant patient.

Jamestown Canyon virus (JtCV) is an arbovirus and a member of the California serogroup. To our knowledge, all the cases of JtCV have been reported in immunocompetent patients since it was first detected in 1997. We report a case of JtCV encephalitis in a solid organ transplant patient. A 48-year-old woman from Wisconsin had multiple hospital admissions for symptoms of progressive confusion, visual hallucinations, and inability to perform self-care. Initial evaluation was significant for lymphocytes in cerebrospinal fluid (CSF), and multiple infectious and metabolic causes were excluded. Further investigation found JtCV IgM in serum, and CSF. The patient's clinical course was compatible with JtCV encephalitis, and she was treated with ribavirin in addition to reduction of her immunosuppressive medications. She showed gradual and significant improvement in her mental and functional status. JtCV can cause a variety of symptoms that range from a flu-like syndrome to encephalitis. There have been an increased number of reported cases in recent years which is attributed to increased physician awareness and the availability of laboratory testing. Optimal treatment is still not known.

Risk factors associated with seropositivity to California serogroup viruses in humans and pet dogs, Quebec, Canada.

Jamestown Canyon and snowshoe hare viruses are two emerging human pathogens associated with cases of neuroinvasive disease in North America. This study aimed to identify environmental and individual risk factors for seropositivity to these arboviruses in humans and pet dogs from Québec, Canada, 2012-2014. In humans, areas with moderate densities of white-tailed deer (Odocoileus virginianus) were associated with higher odds of seropositivity compared with areas with low densities of white-tailed deer (OR 2.50, P = 0.009) and odds of seropositivity were higher in males than in females (OR 2.03, P = 0.016). Among humans reporting more than 10 mosquito bites weekly, the odds of being seropositive were 4.44 times higher (P = 0.004) for people living in hardwood forested areas. Exposure to areas with coniferous forests was identified as the main environmental risk factor for seroconversion in dogs (OR 2.39, P = 0.04). These findings may help target further public health research, diagnostic and surveillance efforts in Canada.

Economic and social impacts of La Crosse encephalitis in western North Carolina.

La Crosse encephalitis (LACE), a human illness caused by a mosquito-transmitted virus, is endemic in western North Carolina. To assess the economic and social impacts of the illness, 25 serologically confirmed LACE case patients and/or families were interviewed to obtain information on the economic costs and social burden of the disease. The total direct and indirect medical costs associated with LACE over 89.6 life years accumulated from the onset of illness to the date of interview for 24 patients with frank encephalitis totaled dollar 791,374 (range = dollar 7,521-175,586), with a mean +/- SD per patient cost of dollar 32,974 +/- dollar 34,793. The projected cost of a case with lifelong neurologic sequelae ranged from dollar 48,775 to dollar 3,090,798 (n = 5). For the 25 LACE patients, 55.15 (54.83%) of the 100.59 cumulative life years (CLYs) were impaired to some degree. Disability adjusted life years (DALYs) were calculated to measure the productive life years lost to LACE. Approximately 13.00 DALYs were accumulated over 100.59 CLYs of study. Projected DALYs for case patients (n = 5) with lifelong neurologic sequelae ranged from 12.90 to 72.37 DALYs. An Impact of La Crosse Encephalitis Survey (ILCES) was used to measure the social impact of LACE over time for case patients and their families. The ILCES scores demonstrated that the majority of the social burden of the illness is borne by the five patients with lifelong neurologic sequelae. The socioeconomic burden resulting from LACE is substantial, which highlights the importance of the illness in western North Carolina, as well as the need for active surveillance, reporting, and prevention programs for the infection.

[The characteristics of the pathogenic properties of new strains of viruses of the California encephalitis antigenic complex isolated in Arkhangelsk Province]. / Kharakteristika patogennykh svoistv novykh shtammov virusov antigennogo kompleksa kaliforniiskogo éntsefalita, izolirovannykh v Arkhangel'skoi oblasti.

Neurotropic properties of Leiv 12724 Ax and Leiv 13004 Ax strains were demonstrated by inoculation of green monkeys, Syrian hamsters and white mice using different routes. The strain Leiv 13004 Ax showed more marked pathogenicity for monkeys and rodents producing lesions in all parts of the brain: temporal, frontal, occipital, cerebellar, medulla oblongata and spinal cord where productive vasculitis, perivascular infiltrations, hemorrhages, and dystrophy of nerve cells were observed. In hamsters, the strains Leiv 13004 Ax and Leiv 12724 Ax inoculated subcutaneously produced latent infection with long-term virus carrier state.

Symptomatic La Crosse virus infections of the central nervous system: a study of risk factors in an endemic area.

In most years, La Crosse virus is the most common cause of reported mosquito-borne illness in the United States. The authors conducted a case-control study to determine if behavioral and environmental factors influenced the risk of La Crosse virus illness. Data were gathered on 31 serologically confirmed cases and 60 age-, sex-, and geography-matched controls in West Virginia in 1987 and 1988. Univariate analysis revealed minimal elevation of disease risk (odds ratios (ORs) less than 2.0) with increased time outdoors, non-use of insect repellent, non-use of air conditioning, lack of screened windows, and not wearing protective clothing. Univariate and multivariate analysis indicated that the presence of tree holes significantly increased disease risk (OR = 8.5 for greater than or equal to 1 tree hole vs. 0 tree holes). The following factors may also increase disease risk, although the findings were not statistically significant: discarded tires (OR = 3.2 for greater than or equal to 10 tires vs. 0-9 tires); non-tire artificial containers (OR = 4.1 for greater than or equal to 6 containers vs. 0-5 containers); and close proximity of the house to the forest edge (OR = 3.2 for 0-49 ft (0-14.9 m) vs. greater than or equal to 50 ft (greater than or equal to 14.9 m)). The authors conclude that the presence of natural breeding sites (tree holes) is an important risk factor for La Crosse virus illness. These results may be important in guiding future efforts aimed at preventing infection with La Crosse virus.

[The capacity of purified staphylococcal anatoxin to correct antigen-specific and antigen-nonspecific immunological defects]. / Sposobnost' anatoksina stafilokokkovogo ochishchennogo ispravliat' antigenspetsificheskii i antigennespetsificheskii immunologicheskie defekty.

Purified staphylococcal toxoid is capable of partially preventing the development of antigen-specific (induced by the supraoptimal dose of sheep red blood cells) and antigen-nonspecific (induced by Tahyna virus) defects of humoral immune response, as well as abolishing these defects. The presence and manifestation of the correction of virus-induced immunodeficiency is determined by the dose of the toxoid and the interval between the injections of purified staphylococcal toxoid and the infective agent.

[The clinico-laboratory characteristics of cases of diseases connected with viruses of the California encephalitis complex in the inhabitants of Moscow]. / Kliniko-laboratornaia kharakteristika sluchaev zabolevanii, sviazannykh s virusami kompleksa kaliforniiskogo éntsefalita, u zhitelei Moskvy.

To study the role of viruses of the California encephalitis virus complex (the family Bunyaviridae) in infectious pathology, 187 fever patients admitted to the Clinical Infectious Hospital in May-September 1986 were examined. In 10 of these patients the neutralization test revealed the presence of diagnostically significant changes in neutralizing antibodies (neutralization indices), which was indicative of the role played by Tahyna virus or other related viruses belonging to the California encephalitis virus complex in the etiology of the diseases. The analysis of the clinical picture showed that in all patients the disease took an acute course in its initial stage, starting with shivering and characterized by high fever, headache, pronounced toxicosis, the possibility of the formation of intracerebral hypertension and pneumonia.

Biological profile of a virus belonging to California encephalitis complex isolated in Karelian Autonomous Soviet Socialist Republic.

We investigated in white mice and in Syrian hamsters the pathogenesis of infection with a virus belonging to the California encephalitis complex isolated in the Karelian Autonomous Soviet Socialist Republic. The pathogenic properties of the virus were investigated also in green monkeys. The localization and character of lesions in the organs of given animals appeared to be similar. The virus appeared to possess neurotropic activity, it propagated in the animal body by haematogenous route. The virus was found to be heat-resistant and pH-sensitive.

Human infections with La Crosse virus in Georgia, 1982.

Eight cases of central nervous system infection due to La Crosse (California serogroup) virus were detected in Georgia children in 1982. The patients were residents of the state, without histories of travel away from the vicinities of their homes during the 30 days before the onset of their illnesses. All were hospitalized with a diagnosis of aseptic meningitis or encephalitis; none had sequelae. Onset dates were from May 1 to Aug 30. Distribution of cases within the state suggested that active transmission of La Crosse virus occurred at least in the southeast quadrant of the state. The epidemiology and natural cycle of La Crosse in the southeastern United States are briefly discussed.

Mechanisms of bunyavirus virulence. Comparative pathogenesis of a virulent strain of La Crosse and an avirulent strain of Tahyna virus.

To analyze mechanisms of virulence in the California serogroup bunyaviruses, the virulent La Crosse/original (LAC/original) strain was compared with the avirulent Tahyna/181-57 strain. In suckling mice, both viruses were lethal upon intracerebral injection but differed markedly in their neuroinvasiveness following subcutaneous injection; 20 and 20,000 plaque-forming units, respectively, were equivalent to 1 subcutaneous LD50. The sequential course of infection was followed after subcutaneous injection of 700 plaque-forming units; LAC/original replicated in striated muscle, caused a high titer plasma viremia, invaded the central nervous system, and killed all mice; the same dose of avirulent Tahyna/181-57 failed to replicate in extraneural tissues, did not invade the central nervous system, and caused no apparent illness. Immunofluorescent examination of peripheral and central nervous system tissues showed the same distinctions between virulent and avirulent viruses and pinpointed striated muscle as the major extraneural target of virulent LAC/original virus. Paradoxically, after intracerebral injection of suckling or adult mice, Tahyna/181-57 virus killed more quickly than LAC/original. This difference was correlated with replication differences; Tahyna/181-57 multiplied marginally faster in the brain than did LAC/original virus.