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PubMed1992

Serologic survey for selected arboviruses and other potential pathogens in wildlife from Mexico.

During 1988 and 1989, a serologic survey of wildlife was conducted in northeastern Mexico to determine the presence, prevalence, and distribution of arboviruses and other selected disease agents. Eighty mammal specimens were tested. Antibodies to vesicular stomatitis-Indiana, Venezuelan equine encephalitis-Mena II, Rio Grande virus, and vesicular stomatitis-New Jersey were detected predominantly in small mammals. Deer and mouflon (Ovis musimon) had antibodies to bluetongue and epizootic hemorrhagic disease. Two species had serologic evidence of recent exposure to Francisella tularensis. A white-tailed deer (Odocoileus virginianus) had antibodies to Anaplasma marginale. All specimens tested for antibodies against Yersinia pestis and Brucella abortus were negative. Sera from 315 birds were tested for antibody against five equine encephalitis viruses and six avian pathogens. During 1988, antibodies to Venezuelan equine encephalitis-Mena II, Venezuelan equine encephalitis-TC83, St. Louis encephalitis, eastern equine encephalitis, and western equine encephalitis were detected in birds of several species. Antibodies to Pasteurella multocida and Newcastle disease virus were also detected. Birds from five species presented antibodies to Mycoplasma meleagridis. Specimens tested for M. gallisepticum, M. synoviae, and Chlamydia psittaci were negative. To the best of our knowledge, this survey represents the first serologic evidence of bluetongue, Cache Valley virus, epizootic hemorrhagic disease, Jamestown Canyon virus, vesicular stomatitis-Indiana, vesicular stomatitis-New Jersey, Rio Grande virus, and tularemia reported among wildlife in Mexico.

Animals↗
PubMed1998

Mosquito feeding-induced enhancement of Cache Valley Virus (Bunyaviridae) infection in mice.

Cache-Valley (CV) virus, an arthropod-borne bunyavirus, recently has emerged as a significant veterinary pathogen causing infertility and congenital malformations in North American ruminants. To investigate the role of vector feeding on CV infection, adult mice were injected subcutaneously with CV, CV and vector thorax extract (a source of vector saliva), or CV into the site of intense, noninfected-mosquito feeding. Mice did not become infected after injection of CV or CV and vector saliva, nor did they produce antibodies to CV. However, injection of CV into sites of mosquito feeding resulted in viremia and production of anti-CV antibody by 2 wk after infection. This enhancement of CV infection resulted after feeding by Aedes triseriatus (Say), Ae. aegypti (L.), or Culex pipiens (L.). Enhancement occurred when injection was delayed up to 4 h after mosquito feeding, but it was not observed when virus injection was performed at a site distant from mosquito feeding. These results indicate that arbovirus infection may be enhanced by mosquito-vertebrate host interactions and that replication of arboviruses in arthropod vectors may not be responsible for increased virulence of infections mediated by infected arthropods. Enhanced CV infection in pregnant mice did not result in infertility or malformed pups, indicating that the mouse is not a suitable model to study CV-induced malformations.

Aedes↗
PubMed1993

Distribution of western equine encephalomyelitis virus in the alimentary tract of Culex tarsalis (Diptera: Culicidae) following natural and artificial blood meals.

The distribution of western equine encephalomyelitis (WEE) virus in the alimentary tract of Culex tarsalis (Coquillett), following blood feeding, was examined using autoradiography. Following engorgement on chicks circulating radiolabeled virus, WEE virus in all mosquitoes was concentrated at the margins of the abdominal midgut, adjacent to the epithelium. Thirty percent of mosquitoes also contained small amounts of virus in the foregut, ventral diverticulum, and/or thoracic midgut. Mosquitoes imbibing labeled virus in hanging drops containing washed blood cells and sucrose showed an altered distribution of WEE virus. Virus was not concentrated adjacent to the abdominal midgut epithelium, and all mosquitoes contained large amounts of WEE virus in most regions of the thoracic alimentary tract. These findings may help explain the increased thresholds of infection associated with artificial feeding techniques and indicate that artificial blood meals may alter the sites of initial arbovirus infection within the alimentary tract of mosquito vectors.

Animals↗
PubMed1999

Australia's notifiable diseases status, 1998. Annual report of the National Notifiable Diseases Surveillance System.

In 1998 there were 85,096 notifications to the National Notifiable Diseases Surveillance System; slightly lower than in 1997 (89,579). The number of measles cases remained low, and well below the number reported in the outbreak years of 1993 and 1994. Rubella notifications further decreased and remained low in 1998. The Measles Control Campaign from August to November 1998, did not impact significantly on the number of measles or rubella cases reported for 1998. Notifications of Haemophilus influenzae type b reached a record low since surveillance began in 1991, and appeared to have stabilised at a low rate since the introduction of the conjugated vaccine in 1992. The previously reported outbreak of pertussis in 1997 tapered off in early 1998. Food-borne disease, or detection of disease, appeared to be on the rise with an increase in notification rates of campylobacteriosis and salmonellosis. Notifications of hepatitis A decreased, correcting the previous high number of notifications in 1997. Sexually transmissible diseases (STDs) increased. Notifications for chlamydial infection were the highest for all sexually transmitted diseases and third highest for all notifiable diseases. Notifications of gonococcal infection also continued to rise and have doubled since 1991, whilst notifications for syphilis increased slightly after falling steadily over recent years. Arbovirus infections of concern in 1998 were dengue outbreaks in Far North Queensland and the first case of Japanese Encephalitis for mainland Australia, highlighting the importance of surveillance of arboviruses and vectors for their detection and management.

Australia↗
PubMed1999

Electron microscopic diagnosis of human flavivirus encephalitis: use of confocal microscopy as an aid.

The distinction between intracranial viral infections and inflammatory conditions requiring immunosuppression is important. Although specific laboratory reagents are readily available for some viruses, diagnosis of arbovirus infection is more difficult. Transmission electron microscopy (TEM) theoretically allows identification of viral particles independent of reagent availability, but it has limited sensitivity. We report two cases of human flavivirus encephalitis diagnosed by TEM. Laser scanning confocal microscopy (LSCM) was used in one case to survey unembedded tissue slices for focal abnormalities, from which fragments smaller than 1 mm2 were excised for epoxy embedding. This facilitated TEM identification of intracytoplasmic, budding, 35-40 nm spherical virus particles, confirmed by serology as St. Louis encephalitis. In contrast to mosquitoes and newborn mice, in which high viral loads are associated with minimal tissue responses, these biopsies showed florid angiodestructive inflammation and microgliosis, with rare virions in necrotic perivascular cells and astrocytes. To our knowledge, this represents the first ultrastructural study of St. Louis encephalitis in humans, indicating the potential value of LSCM-aided TEM.

Adult↗
PubMed1978

Aedes albopictus cells release a goose red blood cell agglutinin.

The presence of a goose red blood cell (RBC) agglutinin (HA) in the culture medium of apparently uninfected Aedes albopictus cells raised the possibility of contamination by an arbovirus. The HA sedimented in sucrose gradients between 18S and 28S and had a buoyant density in sucrose of 1,23 g/cm3. The HA adsorbed to concanavalin A-Sepharose and could be eluted with alpha-methyl-D-mannoside. The apparent molecular weights of the eluted glycoproteins were estimated by PAGE to range from 17,000 to 45,000. Treatment of culture medium from A.albopictus cells with excess goose RBC removed both HA activity and a proportion of the proteins of molecular weight 25,000--35,000. The HA also bound to human group 'O' RBC, It was not possible to inhibit hemagglutination with a variety of anti-arbovirus antisera. These data do not support the hypothesis that the HA is associated with an inapparent arbovirus infection of A.albopictus cells.

Aedes↗
PubMed1983

A sero-epidemiological survey for Bunyaviridae and certain other arboviruses in Pakistan.

Complement fixation test reactions to the following viruses were studied in 372 samples (157 rodents, 172 domestic animals, 43 persons) from Pakistan: Bunyaviridae, Phlebovirus: Phlebotomus fever Sicilian (PFS), Phlebotomus fever Naples (PFN), Karimabad (KAR), Salehabad (SAL); Nairovirus: Crimean-Congo haemorrhagic fever (CCHF), Hazara (HAZ), Dera Ghazi Khan (DGK), Dhori (DHO); Uukuvirus: Manawa (MWA); "possible members": Bakau (BAK), Bhanja (BHA). Reoviridae, Orbivirus: Wad Medani (WM). Unclassified: Wanowrie (WAN). Four of these viruses are Phlebotomus-borne (PFS, PFN, KAR, SAL). The other nine ar tick-borne. Antibodies against each virus were detected in sera from rodents. Antibodies against PFS, PFN, KAR, CCHF, DGK, BHA, WM and WAN viruses were detected in sera from domestic animals. Antibodies against PFS, CCHF, DGK, DHO, MWA, BHA, and BHA and WAN viruses were detected in human sera. The presence in Pakistan of KAR, DHO, BHA, and WAN viruses is documented for the first time. Over-all prevalence rates were highest for BHA (12.1%) and WM (10.7%) viruses, followed by DGK, CCHF, PFN and PFS (4.0 to 5.4%) and DHO, KAR, WAN, SAL, MWA, BAK and HAZ (0.3 to 2.1%). Epidemiological factors relating to virus circulation and human disease are discussed.

Adult↗
PubMed1998

Surveillance for arthropod-borne viral activity in Nebraska, 1994-1995.

A 2-yr arbovirus surveillance program was established in Nebraska following the midwest flood of 1993. CDC light traps were used to collect mosquitoes at 11 localities throughout Nebraska. In 1994, we collected 685,582 mosquitoes, and we tested 1,359 pools of Culex mosquitoes for arbovirus infection, with St. Louis encephalitis virus isolated from 2 pools collected in Scotts Bluff County in western Nebraska. In 1995, 1,163,741 mosquitoes were collected and 2,788 pools tested, with 36 positive for western equine encephalomyelitis (WEE) virus. Thirty of the WEE-positive pools were collected in Scotts Bluff County, 4 pools from the city of Norfolk and 2 from the city of Grand Island. All viruses were isolated from Culex tarsalis Coquillett. The highest minimum infection rate of 3.81 per 1,000 mosquitoes was observed in Scotts Bluff County on 13 September 1995. The seasonal minimum infection rate for WEE was 0.52 in Scotts Bluff County. No human or horse disease attributed to arboviral infection was reported in Nebraska during 1994 and 1995.

Animals↗
PubMed1992

Evaluation of new anti-infective drugs for the treatment of viral encephalitis. Infectious Diseases Society of America and the Food and Drug Administration.

Viral encephalitis may develop subsequent to viremia, via neuronal spread, or by arthropod vector. Diagnosis often requires invasive studies such as lumbar puncture and brain biopsy. This guideline addresses herpes simplex, rabies, and arbovirus infections of the central nervous system. Clinical trials should be designed according to the availability of approved therapeutic agents. Study designs with an active control (herpesvirus), a placebo control (arbovirus), or no control (rabies virus) are recommended. Outcome should be assessed 4-6 weeks, 4-6 months, and 11-13 months after the completion of therapy. For newborns with encephalitis, outcome should be assessed yearly through the age of 5 years. Assessment of clinical outcome is paramount.

Anti-Infective Agents↗
PubMed1979

Isolation of virus strains from mosquitoes collected in Queensland, 1972-1976.

171,348 mosquitoes and 4,353 other arthropods collected at three centres in Queensland in 1972-1976 yielded 151 strains of 18 viruses. Culex annulirostris was the major source of virus isolation but 42 strains from Aedes normanensis indicate it to be a vector of importance. Ross River and Kokobera viruses were isolated at Kowanyama in the dry season, a finding of interest as being compatible with year-round survival in vector-vertebrate cycles. Culex fatigans has in part replaced Culex annulirostris in peridomestic breeding sites at Kowanyama; the infrequency of virus isolation from it suggests that this replacement may lower arbovirus infection rates. Twelve strains were identified as viruses antigenically distinct from any previously isolated in Australia or New Guinea: Ch16129, showed by the International Reference Centre for Arboviruses to be a previously undescribed member of the Simbu Group (Facey's Paddock virus), Ch16313 (Murweh), Ch19520 (Parker's Farm) and Ch19546 (little Sussex). The remaining strains were identified as viruses previously known in Australia, but included many new host or geographical records.

Aedes↗
PubMed1968

Electron microscopic observations of mouse brain infected with Bunyamwera group arboviruses.

Ultrathin sections of brain tissue from mice infected with three Bunyamwera group arboviruses, Bunyamwera, Tensaw, and Maguari, were examined by electron microscopy. In all three cases, virus was observed budding from membranes into intracytoplasmic cisternae. Mature virus was found accumulated within these distended cisternae and in extracellular spaces. The three viruses were morphologically indistinguishable; particles were round or oval, 98 nm in diameter, and had a closely adherent irregular envelope.

Animals↗
PubMed1996

Arboviruses causing neurological disorders in the central nervous system.

Arthropod-borne viruses are important causes of diseases of the central nervous system. In addition to the tick-borne encephalitis viruses, other arboviruses in Europe are known to cause neurological disorders. Among them are West Nile, California group, Bhanja, Erve, Kemerovo group, Eyach, and Thogoto viruses. The ecologies and epidemiologies of these viruses are presented and their medical importance as travel-related diseases is discussed.

Animals↗
PubMed1984

[West Nile virus meningomyeloencephalitis--value of interferon assays in primary encephalitis].

A 68 year-old woman contracted West Nile fever after a stay of one month in Israel. Mild encephalitis and severe myelitis, resembling the "polio syndrome", developed, with important sequelae. Specific antibodies against West Nile fever virus progressively increased in the patient's serum. Epidemiological and clinical data about neurologic aspects of this infection are reviewed. Meningoencephalitis is not unusual, but only one previous case of acute anterior myelitis has been described in humans although this pathology is well known in experimental and veterinary diseases. Very few studies concern interferon and arbovirus infections in humans. Interferon assays in our patient's serum and cerebrospinal fluid showed its presence and persistence: this is in relation with the replication of the virus in the central nervous system, as it has been demonstrated in other primary viral encephalitis.

Aged↗
PubMed1970

Antiviral activity of chlorite-oxidized oxyamylose, a polyacetal carboxylic acid.

Intraperitoneal injection of chlorite-oxidized oxyamylose (COAM) protected mice against mengo, vaccinia, Semliki Forest, and influenza APR8 viruses. Topical administration in the eye of rabbits partially inhibited the development of experimental herpetic keratoconjunctivitis. COAM resembled polyacrylic acid in many aspects, but it was markedly less toxic. For systemic administration, the therapeutic index was on the order of magnitude of 1:300 to 1:500. Although the in vivo antiviral effect of COAM wore off faster than that of polyacrylic acid, protection lasted for several weeks. Against mengovirus, such prolonged protection was achieved only when polymer and virus were injected intraperitoneally. Protection against intravenous vaccinia virus was not dependent on the injection route of COAM. Experiments on the mode of action of COAM pointed to macrophages as possible mediators of the antiviral effect. The fact that small amounts of interferon appeared in the serum after administration of high doses of COAM suggests that interferon may play a role in the induction of antiviral resistance by COAM.

Acids↗
PubMed1976

Avian arboviruses of the Witless Bay seabird Sanctuary, Newfoundland, Canada.

A virologic and serologic survey of arbovirus infections among seabirds and seabird ticks, Ixodes uriae, on Great Island. Witless Bay, Newfoundland, Canada, was conducted during 1971 and 1972. Kermerovo (Great Island, Bauline) and Sakhalin (Avalon) group viruses previously reported from birds and/or ticks on Great Island were prevalent among avian populations, while conclusive evidence of known nonindigenous serotypes was lacking. Circumstantial evidence-hemagglutination inhibiting antibody-of an unidentified member of the group B tick-borne encephalitis complex transmitted among marine birds of North America by I. uriae is reported. No evidence of human infections with any of these viruses was detected in a small number of biologists doing research on Great Island.

Animals↗