Major Outbreak (major + outbreak)

Distribution by Scientific Domains

Selected Abstracts

Over expression of a Cytochrome P450 (CYP6P9) in a Major African Malaria Vector, Anopheles Funestus, Resistant to Pyrethroids

D. A. Amenya
Abstract Anopheles funestus Giles is one of the major African malaria vectors. It has previously been implicated in a major outbreak of malaria in KwaZulu/Natal, South Africa, during the period 1996 to 2000. The re-emergence of this vector was associated with monooxygenase-based resistance to pyrethroid insecticides. We have identified a gene from the monooxygenase CYP6 family, CYP6P9, which is over expressed in a pyrethroid resistant strain originating from Mozambique. Quantitative Real-Time PCR shows that this gene is highly over expressed in the egg and adult stages of the resistant strain relative to the susceptible strain but the larval stages showed almost no difference in expression between strains. This gene is genetically linked to a major locus associated with pyrethroid resistance in this A. funestus population. [source]

Effects of variable phytochemistry and budbreak phenology on defoliation of aspen during a forest tent caterpillar outbreak

Jack R. Donaldson
Abstract 1,The present study assessed the relationship between clonally variable rates of defoliation in trembling aspen (Populus tremuloides Michx.) and two potential resistance traits: defensive chemistry and leaf phenology. 2,In 2001, coincident with a major outbreak of the forest tent caterpillar (Malacosoma disstria Hubner) in the northcentral U.S.A., we monitored defoliation rates, phytochemical composition, and foliar development in 30 clones of trembling aspen. Leaf chemistry was also assessed in re-flushed leaves and 2 years post-outbreak. 3,Early in the season, differences in defoliation among clones were substantial but, by mid-June, all clones were completely defoliated. Leaf nitrogen, condensed tannins, and phenolic glycosides varied among clones but did not relate to defoliation levels. Budbreak phenology differed by 3 weeks among clones and clones that broke bud early or late relative to forest tent caterpillar eclosion experienced reduced rates of defoliation. 4,Defoliation led to increased tannins and slight decreases in phenolic glycoside concentrations in damaged leaf remnants, but to moderately decreased tannins and a six-fold increase in phenolic glycosides in reflushed leaves. This shift in chemical composition may significantly affect late season herbivores. 5,These results suggest that aspen chemical resistance mechanisms are ineffective during intense episodic eruptions of outbreak folivores such as the forest tent caterpillar. Variable budbreak phenology may lead to differential susceptibility during less intense outbreak years and, at peak forest tent caterpillar population densities, mechanisms affording tolerance are probably more important than chemical defences. [source]

Isolation of caprine herpesvirus 1 from a major outbreak of infectious pustular vulvovaginitis in goats

KL Piper
We describe an outbreak of infectious pustular vulvovaginitis caused by Caprine herpesvirus 1 (CpHV1) in a group of approximately 200, 8 month old virgin does that were imported to Victoria from New Zealand. CpHV1 was isolated in cell cultures from vaginal swabs from three of three affected does but not from two bucks that had been with the does. The identity of the virus as a herpesvirus was confirmed by negative stain electron microscopy. Restriction endonuclease DNA fingerprint analysis showed that the DNA fingerprints were similar, but not identical, to previously described CpHV1 isolates made in New Zealand, New South Wales, and in other parts of the world. Acute and convalescent phase sera from selected does supported the diagnosis of CpHV1 infection. It is most likely that the disease was initiated by reactivation of latent virus in at least one of four bucks that served the does, since each was positive for CpHV neutralising antibody when first tested. This is the first report of CpHV infectious pustular vulvovaginitis in goats in Victoria and to our knowledge appears to be one of the largest outbreaks recorded anywhere. [source]

Sandfly fever virus outbreak in Cyprus

A. Papa
Abstract A major outbreak of febrile syndrome occurred during 2002 among the Greek Army forces in Cyprus. Serological and molecular investigations revealed that the causative agent was a Sicilian-like phlebovirus. A virus strain was isolated from a blood sample taken on the first day of the disease. Phylogenetic analysis of partial L RNA segment sequences revealed that the strain from Cyprus differed from sandfly Sicilian virus by 6.7% at the nucleotide level. [source]

Use of episcopic differential interference contrast microscopy to identify bacterial biofilms on salad leaves and track colonization by Salmonella Thompson

J. C. Warner
Summary Zoonotic pathogens such as Salmonella can cause gastrointestinal illness if they are ingested with food. Foods such as salads pose a greater risk because they are consumed raw and have been the source of major outbreaks of disease from fresh produce. The novel light microscopy methods used in this study allow detailed, high resolution imaging of the leaf surface environment (the phyllosphere) and allow pathogen tracking. Episcopic differential interference contrast microscopy coupled with epifluorescence was used to view the natural microflora in situ on salad leaves and their topographical distribution. Fluorescent nucleic acid staining was used to differentiate between bacterial colonists and inorganic debris. Salmonella enterica serovar Thompson expressing green fluorescent protein was inoculated onto individual spinach leaves for 24 h at 22C in order to observe spatial and temporal patterning of colonization on the two surfaces of each leaf under different osmotic conditions. The results obtained show that salad leaves are host to high numbers of bacteria, typically 105 per square millimetre. Cells are present in complex three-dimensional aggregations which often have a slimy appearance, suggesting the presence of biofilms. Washing of the leaves had little effect on the number of adherent pathogens, suggesting very strong attachment. Episcopic differential interference contrast microscopy is a rapid alternative to both scanning electron microscopy and confocal laser scanning microscopy for visualizing leaf topography and biofilm formation in the natural state. [source]

Change in hepatitis A virus seroepidemiology in southern Taiwan: a large percentage of the population lack protective antibody

Shih-Min Wang
Abstract Hepatitis A, the predominant reported etiologic form of viral hepatitis in Taiwan, continues to be a disease primarily of children and young adults. A seroepidemiologic study was performed to assess the seroprevalence of hepatitis A (HAV) antibodies in the southern Taiwan general population in 1998 and is compared with results of a similar study in 1992. A total of 948 subjects (477 male and 471 female) with ages ranging from 0.3 to 63 years were stratified into 14 age-specific groups. The presence of anti-HAV antibodies was detected using a commercially available radioimmunoassay. Fifteen percent of the subjects were positive for anti-HAV antibodies, which is lower than that in 1992 (P,<,0.001). Seroprevalences were 14.1% for males and 22.6% for females (P,=,0.006). The pattern of anti-HAV seroprevalence was distinguishable from that found in 1992; minimum seroconversion occurred at ages ranging from 1 to 30 years. Prevalence of seropositive subjects decreased markedly for the <,1, 13,15, 16,19, 20,24, 25,29, and 30,39 year age groups in comparing 1998 with 1992. The current study demonstrates a continuing decline in the prevalence of HAV among children, adolescents, and young adults. The findings can be ascribed to the improvement of socioeconomic status and modernization of environmental sanitation. As a consequence of this changing trend of endemicity and the resulting lack hepatitis A antibodies among the general population in Taiwan, the risk of sudden major outbreaks is increased because of increasing international travel and immigration, particularly during and after natural disasters. HAV vaccination will be important for the prevention and control of HAV outbreaks in the community. J. Med. Virol. 64:104,108, 2001. 2001 Wiley-Liss, Inc. [source]

Mumps: Not an Innocent Bystander in Solid Organ Transplantation

M. C. Baas
Recently two major outbreaks of mumps have occurred: in the UK more than 56,000 cases were notified between 2004 and 2005, and in the United States, 6,584 cases were reported in 2006. Most patients were young healthy adults, in whom mumps normally has a benign course. Little is known about mumps in the immunocompromised patient. Here, we report a case of a 56-year renal transplant recipient who developed acute irreversible transplant failure due to interstitial nephritis caused by mumps. RNA of the mumps virus was detected in the urine as well as in a renal biopsy. In view of the ongoing presence of the mumps virus in the population, one should be aware of the possible occurrence of this infection in immunocompromised patients. [source]