Amblyomma americanum: a potential vector of Lyme disease in New Jersey.

Amblyomma americanum is a likely secondary vector of Lyme disease in New Jersey. Ticks of this species were removed from the site of the characteristic skin lesion known as erythema chronicum migrans on two patients with the disease, and the Lyme disease spirochete was isolated from nymphs and adults of this species. That A. americanum is a potential vector is supported by its similarities to Ixodes dammini, the known tick vector, in seasonal distribution and host utilization. The extensive range of A. americanum may have great implications for potential Lyme disease transmission outside known endemic areas.

Experimental infection of North American mammals with epidemic Venezuelan encephalitis virus.

Eighty-three wild mammals of ten species were inoculated with a first mouse passage level Venezuelan encephalitis (VE) virus isolated from south Texas in 1971 during the VE outbreak. Rodents were highly susceptible to VE infection and circulated VE virus at levels ranging from 10(7.7) to 10(11.5) suckling mouse intracranial lethal doses per ml for 2 to 4 days. These levels of virus could easily infect vector mosquitoes. Mortality was high in all species of rodents except Sigmodon hispidus, adult Neotoma micropus, and adult Peromyscus leucopus. Lagomorphs were susceptible to VE infection but circulated VE virus at or near mosquito threshold levels for 1 day only. Raccoons and opossums were relatively resistant to VE infection or circulated low levels of virus in the blood. Juvenile animals of four species were more susceptible and experienced higher viremias than did adults. In two of the four, mortality was higher in the juveniles than in adults. A consideration of results obtained during this study and those of other investigators led to the conclusion that equines were of major importance, that canines, lagomorphs and rodents were of minor importance, and that other species tested were of no importance as virus amplifiers in VE epizootics.

Prolonged western equine encephalitis viremia in the Texas tortoise (Gopherus berlandieri).

Subcutaneous inoculation of 34 Texas tortoises (Gopherus berlandieri) with either of two strains of Western Equine Encephalitis (WEE) virus resulted in prolonged viremia of up to 105 days' duration. Peak viremia titers exceeded 10(6) suckling mouse intracranial lethal doses per milliliter. The length of the previremic period, the maximum viremia level attained, and the duration of viremia were markedly affected by environmental temperature. Higher temperatures (30 degrees C) shortened the previremic period and the duration of viremia and elevated the maximum viremia level. Lower temperatures had the opposite effect. Mechanisms are suggested whereby Texas tortoises could serve as an overwintering reservoir for WEE virus at any temperature. Neutralizing antibody was detectable following viremia in only 11 of 16 (69%) of surviving tortoises.

Experimental infection of birds with epidemic Venezuelan encephalitis virus.

Sixty-three birds representing 13 species were inoculated with a strain of epidemic Venezuelan encephalitis (VE) virus from the 1971 Texas outbreak. More than 95% of the birds became infected. Mortality which could be attributed to infection with VE virus was very low. Viremia persisted 2-6 days. Peak viremia levels ranged from 10(3.2) to 10(8.2) suckling mouse intracranial 50% lethal doses per milliliter (SMICLD50/ml). Blood virus levels were highest in juvenile Louisiana Herones, adult Robins and adult Mockingbirds and were lowest in juvenile Common Egrets. Most bird species had blood virus levels about 10(5) SMICLD50/ml (high vector infection potential) for 2-3 days. Neutralizing antibody response was more uniform and frequent in herons (95%) than in passerines (56%). The role of birds in the epidemiology of Venezuelan is discussed.

A field study on the effects of Fort Morgan virus, an arbovirus transmitted by swallow bugs, on the reproductive success of cliff swallows and symbiotic house sparrows in Morgan County, Colorado, 1976.

We studied the transmission of Fort Morgan (FM) virus within colonies of nesting Cliff Swallows and House Sparrows under three bridges in Morgan County, Colorado during 1976. Nests were examined, and blood or brain specimens were collected from nestlings once or twice a week. Flying birds and small mammals were also studied. We analyzed nesting activity, virus isolations from nestlings of both species, fledging success, multiple infections within a brood of nestlings, infection frequency by age of nestlings, nestling mortality, and infection frequencies by avian species and bridge site. Fort Morgan virus was isolated from 7% (80/1, 156) of the blood and brain samples collected from nestlings. The duration of viremia for nestling House Sparrows was at least 3-4 days based on virus isolation from sequential blood samples. Viremia of nestling Cliff Swallows and House Sparrows did not reduce fledging success, nor were young nestling sparrows viremic more frequently than older nestling sparrows. Nest destruction (by falling down) was a more important cause of nestling mortality than FM virus infection. All age groups of nestling sparrows were viremic at equal rates, but younger nestlings (less than or equal to 7 days old) were more likely than older nestlings (greater than 7 days old) to develop an encephalitic infection. Among nestling House Sparrows, FM virus infections were clustered in time and space. Nestling House Sparrows with FM virus-infected nest-mates were infected more often than conspecifics whose nest-mates were not infected. We concluded that nestling Cliff Swallows and symbiotic House Sparrows that reside in swallow nesting colonies are the principal vertebrate hosts for the maintenance and amplification of FM virus.

The ecology of Colorado tick fever in Rocky Mountain National Park in 1974. III. Habitats supporting the virus.

Ecologic studies of small mammals in Rocky Mountain National Park (RMNP) were conducted in 1974 in order to identify the specific habitats within the Lower Montane Forest that support Colorado tick fever (CTF) virus. Data was collected on the abundance and distribution of 4 primary rodent species, tick infestation, CTF virus, and neutralizing antibody prevalence. Rodents were captured along transects crossing different habitats. Open stands of ponderosa pine and shrubs on dry, rocky surfaces were found to be important for maintaining CTF virus.

Experimental Colorado tick fever virus infection in Colorado mammals.

One hundred and twenty-four small mammals of six species were inoculated with three strains of Colorado tick fever (CTF) virus to define viremia and neutralizing (N) antibody responses. Adult Eutamias minimus and Eutamias embrinus, and juvenile Peromyscus maniculatus and Spermophilus lateralis, were highly susceptible to development of viremic infection. Adult S. lateralis and P. maniculatus were moderately susceptible (greater than or equal to 50% viremic). Five Sylvilagus nuttalli did not become viremic following experimental inoculation. Spermophilus richardsoni was also relatively resistant (less than or equal to 50% viremic). The longest duration of viremia (mean 15.8 days) and highest peak viremia levels (mean peak titer 10(3.9 plaque-forming units per ml) occurred in E. minimus. Adult E. umbrinus, juvenile S. lateralis, and juvenile P. maniculatus had moderate viremias. Adult S. lateralis and S. richardsoni often had short viremias during which virus was only intermittently detectable. N antibody production was most rapid in E. minimus in comparison with other species. In addition, N antibody persisted for 1 year in this species. In other species, many animals lost detectable antibody 5-11 months after infection. No significant differences were found in patterns of infection between three CTF virus strains. We conclude that of the six species inoculated, E. minimus is the best experimental host for CTF virus.

Geographic variation among St. Louis encephalitis virus strains in the viremic responses of avian hosts.

We studied the capacity of 44 strains of St. Louis encephalitis (SLE) virus to induce viremia in an epidemiologically important wild avian host, the House Sparrow (Passer domesticus). Selected virus strains were also inoculated at varying doses into 3-week-old chicks. Viremic responses were analyzed in terms of the proportion of inoculated nestling and adult birds which became viremic, the mean duration and the mean peak titer of viremia. Infectivity of avian sera was determined by plaque assay in primary duck embryo cell cultures. The susceptibility of the House Sparrow to viremic infection with different SLE virus strains varied markedly. Nestling sparrows 6-10 days of age were generally more susceptible than adult birds. All virus strains isolated during Culex pipiens-borne epidemics in the eastern United States were highly viremogenic [viremia in 80% of birds with a mean duration of greater than or equal to 1.6 days in adults or greater than or equal to 2.7 days in nestlings and a mean peak titer of greater than or equal to 10(3.0) plaque-forming units (PFU)/ml in adults and 10(4.0) PFU/ml in nestlings]. All virus strains isolated from Culex tarsalis in the western United States, strains isolated from rodents in South America. and six of 16 strains isolated from various sources elsewhere in tropical America were partially or fully attenuated. A high degree of concordance was demonstrated between experimental viremia in sparrows, viremia in 3-week-old chicks, and neurovirulence for weanling mice. The epidemilogic significance of these findings is discussed.

Experimental infection of house sparrows (Passer domesticus) with Rocio virus.

Rocio encephalitis is a new epidemic flaviviral infection of man, first described in São Paulo State, Brazil in 1975. The ecology of the viral transmission cycle remains largely unknown. Experimental studies were undertaken to assess the role of a wild avian species, the House Sparrow, as a maintenance or amplifying host. Approximately two-thirds of nesting and adult sparrows developed 2- to 3-day viremias of low to moderate magnitude (2.0--4.3 log/ml). Rocio-immune birds were not protected against challenge with St. Louis encephalitis (SLE) virus, but prior SLE viral infection prevented detectable viremia in birds challenged with Rocio virus. These studies provide some support for the hypothesis that birds are hosts for Rocio virus, but the House Sparrow probably plays a relatively minor role in viral transmission. Because sparrows are relatively inefficient viremic hosts, they would be expected to play a minor role in transmission should Rocio virus be introduced into the United States.

Variation in virulence for mice and rhesus monkeys among St. Louis encephalitis virus strains of different origin.

The virulence characteristics of 67 strains of St. Louis encephalitis (SLE) virus isolated from various sources in North, Middle, and South America were compared in mice and rhesus monkeys. Each virus strain was titrated in mice exactly 21 days old and virulence was expressed as the ratio of intracerebral (ic)/intraperitoneal (ip) LD50. Virus strains fell into three groups: 1) high virulence (ic/ip LD50 ratio approximately 1.0); 2) intermediate virulence (variable mortality over a wide dose range); and 3) low virulence (ic/ip LD50 less than or equal to 0.00002). Virus strains isolated during Culex pipiens and Cx. nigripalpus--borne epidemics in the eastern United States were highly virulent for mice, whereas a high proportion of the endemic virus strains isolated from Cx. tarsalis in the western United States were attenuated. Virus strains isolated from birds (the usual host for SLE virus) were highly virulent, in contrast to strains from rodents and carnivores, which were attenuated. Isolates from humans exhibited variable virulence characteristics. In experimentally-infected mice, virulence correlated with high viremia, replication in extraneural tissues, and earlier neuroinvasion. Mouse virulence correlated with clinical and histopathologic markers of pathogenicity for ic inoculated rhesus monkeys. Monkeys immunized with nonpathogenic strains by subcutaneous inoculation were partially protected against ic challenge with a virulent virus strain. The virulence classification of SLE virus strains is discussed in terms of epidemiologic correlations. This classification provides a framework for future studies on the antigenic, genetic, and biochemical bases for SLE virus strain variation.

Arbovirus investigations in Argentina, 1977-1980. I. Historical aspects and description of study sites.

This is the introductory paper to a series on the ecology of arboviruses in Argentina. Epizootics of equine encephalitis have occurred since at least 1908, principally in the Pampa and Espinal biogeographic zones, with significant economic losses; human cases of encephalitis have been rare or absent. Both western equine and eastern equine encephalitis viruses have been isolated from horses during these epizootics, but the mosquitoes responsible for transmission have not been identified. A number of isolations of Venezuelan equine encephalitis (VEE) virus were reported between 1936 and 1958 in Argentina, but the validity of these findings has been seriously questioned. Nevertheless, serological evidence exists for human infections with a member of the VEE virus complex. Serological surveys conducted in the 1960s indicate a high prevalence of infection of humans and domestic animals with St. Louis encephalitis (SLE), and 2 SLE virus strains have been isolated from rodents. Human disease, however, has rarely been associated with SLE infection. Only 7 isolations of other arboviruses have been described (3 of Maguari, 1 of Aura, 2 of Una, and 1 of an untyped Bunyamwera group virus). In 1977, we began longitudinal field studies in Santa Fe Province, the epicenter of previous equine epizootics, and in 1980 we extended these studies to Chaco and Corrientes provinces. The study sites are described in this paper.

Arbovirus investigations in Argentina, 1977-1980. IV. Serologic surveys and sentinel equine program.

Serologic surveys of wild and domestic birds, wild mammals, and horses were conducted during arbovirus field studies in Argentina from 1977 through 1980, a non-epizootic interval. The prevalence of neutralizing antibodies to eastern equine encephalitis (EEE) was consistently higher than to western equine encephalitis (WEE) virus in all species and all areas. The presence of antibodies in short-lived avian species and in young unvaccinated horses and the demonstration of seroconversions in horses during the period, indicated that these viruses are either enzootic in, or annually reintroduced into, Argentina. Antibodies to AG80-646, a new subtype of WEE virus isolated in the subtropical north (Chaco Province) from Culex (Melanoconion) mosquitoes, were found in horses and rodents in that region. Antibodies to the TC-83 strain of Venezuelan equine encephalitis (VEE) virus were found in all areas studied. The presence of antibodies in some horses was probably related to vaccination, but the demonstration of seroconversions in sentinel horses and of antibodies in birds and wild mammals indicates active transmission of VEE virus. In 1980 a new enzootic subtype of VEE virus (AG80-663) was isolated from mosquitoes in Chaco; neutralizing antibodies to this virus were prevalent in horses and rodents in this area. Infections with Aura and Una viruses were most common in the subtropical northern provinces. Infection with St. Louis encephalitis was prevalent and widespread, and birds, principally passerine and columbiform species, appear to be the principal hosts. An interesting and unexplained finding was the absence of arbovirus antibodies, in particular SLE antibodies in house sparrows (Passer domesticus). Antibody prevalences in horses exceeded 50% in all areas, and 12% of horses surveyed in Santa Fe Province developed antibody in a 17-month period. Antibodies to other flaviviruses were rare. A high prevalence of immunity to Maguari virus was found in horses; this agent is considered to be a potential equine pathogen. Antibodies to 2 new viruses, Barranqueras and Resistencia, which had been isolated from Cx. (Melanoconion) in Chaco Province, were found in rodents there. Immunity to Gamboa group viruses was prevalent, and birds were implicated as principal hosts.

Viruses isolated from Aedeomyia squamipennis mosquitoes collected in Panama, Ecuador, and Argentina: establishment of the Gamboa serogroup.

Twenty-four virus strains were isolated from Aedeomyia squamipennis mosquitoes collected in Ecuador. One additional strain each was isolated from this species from Panama and ARgentina. All 26 isolates were shown to be related serologically to prototype Gamboa virus, originally isolated from Ad. squamipennis mosquitoes collected in Panama. Antigenic comparisons of eight strains, including prototype Gamboa virus, indicated the existence of four distinct viruses. Neutralization tests with sera from a variety of mammalian and avian species from Argentina provided further evidence that Gamboa serogroup viruses are transmitted between Ad. squamipennis and birds.

Recovery of Tonate virus ("Bijou Bridge" strain), a member of the Venezuelan equine encephalomyelitis virus complex, from Cliff Swallow nest bugs (Oeciacus vicarius) and nestling birds in North America.

A second virus with distinct biological, serological, and physiochemical properties was detected as a minority viral subpopulation in specimens of Cliff Swallow nest bugs (Oeciacus vicarius) and nestling bird sera containing Fort Morgan (FM) virus. The second virus, detected by a breakthrough neutralization test employing FM antiserum, was present in 5 of 11 FM virus-positive pools of nest bugs and in 4 of 38 birds from Colorado and South Dakota. The concentration of the second virus was 10-fold to 1,000-fold lower than that of FM virus. The second virus, which was provisionally named "Bijou Bridge" (BB) virus was shown by conventional serological tests to be a member of the Venezuelan equine encephalomyelitis (VEE) complex, and by tests employing antisera to the E2 viral glycoprotein to be identical with Tonate virus, previously isolated from birds and mosquitoes only in French Guiana. Experimental infection of House Sparrows and Cliff Swallows showed that they develop brief BB viremias and antibodies. Oe. vicarius bugs were resistant to oral infection with BB virus. The epidemiological significance of recovery of Tonate virus in North American is discussed.

The ecology of Colorado tick fever in Rocky Mountain National Park in 1974. II. Infection in small mammals.

Field studies of Colorado tick fever (CTF) in small mammals in Rocky Mountain National Park (RMNP) in 1974 established that Eutamias minimus and Spermophilus lateralis were the most important hosts for CTF virus and were the source of virus for immature stages of the tick vector, Dermacentor andersoni. Other species (Peromyscus maniculatus, Spermophilus richardsonii, Eutamias umbrinus) are secondary hosts. The intensity of viral activity in rodents varied greatly from locality to locality. Highest rodent infection rates were found to occur in the Moraine Park area of RMNP. Lowest infection rates occurred above 3,290 meters in altitude at Rainbow Curve and on the tundra. The prevalence of infection in rodents was constant from April--July (5--6% of animals captured were viremic) and then declined to 1.7--2.5% in August and September coincident with a decline in nymphal tick ectoparasitism. Many animals were captured which were simultaneously viremic and antibody-positive. Under field conditions, neutralizing antibody seroconversion does not always occur.

Creating an agenda for research and evaluation: HIV service delivery, the Ryan White CARE Act, and beyond.

HRSA, AHCPR and NCAP convened a working meeting in November 1992, to discuss creation of a national agenda for research and evaluation on HIV service delivery systems that are cost-effective, responsive to the needs of the diverse populations affected by the epidemic, and reflective of the lessons learned so far. In this article, the interests and goals of the conveners are described, the meeting's process and outcomes are discussed, and the nine key study areas that were identified and chosen by the meeting participants are presented. It is hoped that this article will stimulate further interest among private and public funders and among the research community in fostering the implementation of HIV service delivery-related research and evaluation studies. If this is accomplished, decision-makers will be better enabled to make informed and responsive policy decisions.

States' responses to Title II of the Ryan White CARE Act.

Title II of the Ryan White Comprehensive AIDS Resources Emergency (CARE) Act of 1990 provides formula-based grants to States to help them improve the quality, availability, and organization of health care and support services for people with human immunodeficiency virus (HIV) infection. This article reviews State expenditures during the first year of CARE Act funding (April 1991-March 1992) within the context of Title II guidelines and the federally funded grant programs that preceded and helped shape Title II. The authors also discuss future challenges that require development of resources, the assessment of program impact, and the evaluation of the quality and appropriateness of HIV-related services. Ninety-one percent of the $77.5 million awarded to States during fiscal year 1991 went for the provision of medical and support services through HIV care consortia, drug reimbursement programs, home and community-based care programs, and health insurance initiatives. The remaining monies were used for planning, evaluation, and program administration. Forty States allocated $38.9 million for the establishment of HIV care consortia to assess service needs and to develop comprehensive continuums of health and support services in the areas most affected by HIV disease. Fifty States allocated an additional $28.3 million for the continuation or expansion of FDA-approved drug therapies for low-income people with HIV infection. Twenty-five States allocated $2.2 million for the provision of home- and community-based health services, and 16 States allocated $1.3 million for programs that help low-income people with HIV infection to purchase or maintain health insurance coverage.

Current CDC efforts to prevent and control human immunodeficiency virus infection and AIDS in the United States through information and education.

The human immunodeficiency virus (HIV) is estimated to have infected more than a million people in the United States and millions more in other countries. Even though there is no vaccine or effective treatment, HIV infection can be prevented through behavioral change. As the lead Public Health Service Agency for disease prevention, the Centers for Disease Control (CDC) has designed and implemented information and education activities with the ultimate goal of preventing HIV infection and AIDS in the United States. The target populations include the general public, school- and college-aged populations, persons infected or at increased risk of infection, minorities, and health workers. Because AIDS will be with us for a long time, CDC views educating the public as a long-term undertaking. The agency has initiated an intensive continuing national public information campaign, an informational brochure to be distributed to every U.S. household, a national AIDS information toll-free hotline, and a clearinghouse system that will maintain a comprehensive inventory of AIDS information resources and services. CDC also supports public information and education efforts by State and local health agencies. To reach school- and college-age youth, CDC, in consultation with governmental and national private sector organizations, developed guidelines for effective school health education to assist school health personnel in determining the scope and content of AIDS education. CDC also works with State and local education agencies to help carry out and evaluate educational efforts to prevent the spread of HIV among school- and college-age youth. The populations with the highest priority for AIDS information and education efforts are those who are at increased risk of acquiring or transmitting the AIDS virus because they use illicit intravenous drugs and share needles, engage in anal intercourse, have many sexual partners, practice prostitution, or engage in sex with those who practice these behaviors. Another high-priority population, because they can infect their offspring,is reproductive age women engaging in high-risk behavior and women infected with HIV who become pregnant. CDC programs targeted to these groups include community health education and risk reduction interventions, counseling and testing for HIV infection, AIDS community demonstration projects, perinatal AIDS prevention projects,and programs focused on preventing AIDS in minority populations. CDC is developing a variety of educational approaches for health workers in clinical settings because they are an important channel for providing accurate AIDS information, helping to assess risk, and counseling to actively reduce risk for the patient, sex partners of the patient, friends, and family members of the patient. CDC has conducted research and provided information and training on the use of HIV laboratory tests. CDC has also developed numerous scientific and technical guidelines and recommendations in consultation with practitioners, public health officials, and others and disseminated these through the Morbidity and Mortality Weekly Report. In addition,CDC has provided information about the risk of HIV transmission in the workplace and about methods of prevention. CDC will continue to evaluate these activities and support research in education and related interventions that may be necessary to prevent infection by the HIV virus. By providing educational support for behavior changes that decrease HIV transmission, we can contribute to AIDS prevention in the 1990s.

First year of AIDS services delivery under Title I of the Ryan White CARE Act.

This is a review of (a) the emergency assistance for ambulatory HIV medical and support services provided in the first year by eligible metropolitan areas (EMAs) funded under Title I of the Ryan White Comprehensive AIDS Resources Emergency (CARE) Act of 1990, (b) the varied responses and processes by which the 16 urban areas receiving Title I funds in 1991 met legislative mandates, (c) the central nature of planning councils under Title I and their formation and functioning, and (d) issues related to current implementation and future expansion of Title I to additional eligible metropolitan areas. Integral to the review is a brief discussion of the history of AIDS and HIV infection, particularly in cities receiving CARE Act funding, an overview of Title I requirements, and a description of the organizational structures cities are using to implement Title I. Information on Title I EMAs is based on analysis of their 1991 applications, bylaws of their HIV service planning councils, intergovernmental agreements between Title I cities and other political entities, and contracts executed by Title I grantees with providers for the delivery of services. Interviews with personnel in several Title I EMAs, including planning council members and grantee staff members, provided additional information. This is the first descriptive accounting of activities related to the 1991 applications for and uses of Title I funds, and the administrative and service issues related to this process.

Delivery of oral health care through the Ryan White CARE Act to people infected with HIV.

The Ryan White Comprehensive AIDS Resources Emergency (CARE) Act of 1990 was passed by Congress "to improve the quality and availability of care for individuals and families with HIV disease." The act targets those individuals infected with HIV who lack financial resources to pay for care. While provision of oral health care is not mandated by the legislation, many oral health services are supported through five different programs receiving CARE Act funding. Legislative mandates, program guidance materials, grant applications, and other related materials were reviewed to analyze oral health care services supported or proposed through the CARE Act. In fiscal year 1991, an estimated $5.8 million of the total CARE Act funds ($229.6 million) were used for oral health care, and there is evidence that oral health concerns will receive increasing attention by grantees in future years. Opportunities exist for local oral health professionals to become involved in CARE Act programs and in the priority development process. It is possible that CARE Act grantees will serve as catalysts for the development of partnerships between private practitioners and public sector programs--relationships that could lead to improved access and quality of care for people with HIV infection.