Showing papers in "Vector-borne and Zoonotic Diseases in 2008"
TL;DR: It is proposed that some cases of rickettsiosis reported as RMSF may have been caused by "R. amblyommii" transmitted through the bite of A. americanum, a preferred hosts of lone star ticks.
Abstract: Cases of Rocky Mountain spotted fever (RMSF) in North Carolina have escalated markedly since 2000. In 2005, we identified a county in the Piedmont region with high case numbers of RMSF. We collected ticks and examined them for bacterial pathogens using molecular methods to determine if a novel tick vector or spotted fever group rickettsiae (SFGR) might be emerging. Amblyomma americanum, the lone star tick, comprised 99.6% of 6,502 specimens collected in suburban landscapes. In contrast, Dermacentor variabilis, the American dog tick, a principal vector of Rickettsia rickettsii, comprised < 1% of the ticks collected. Eleven of 25 lone star tick pools tested were infected with "Rickettsia amblyommii," an informally named SFGR. Sera from patients from the same county who were presumptively diagnosed by local physicians with a tick-borne illness were tested by an indirect immunofluorescence antibody (IFA) assay to confirm clinical diagnoses. Three of six patients classified as probable RMSF cases demonstrated a fourfold or greater rise in IgG class antibody titers between paired acute and convalescent sera to "R. amblyommii" antigens, but not to R. rickettsii antigens. White-tailed deer, Odocoileus virginianus, are preferred hosts of lone star ticks. Blood samples collected from hunter-killed deer from the same county were tested by IFA test for antibodies to Ehrlichia chaffeensis and "R. amblyommii." Twenty-eight (87%) of 32 deer were positive for antibodies to E. chaffeensis, but only 1 (3%) of the deer exhibited antibodies to "R. amblyommii," suggesting that deer are not the source of "R. amblyommii" infection for lone star ticks. We propose that some cases of rickettsiosis reported as RMSF may have been caused by "R. amblyommii" transmitted through the bite of A. americanum.
261 citations
TL;DR: A double-blind placebo-controlled randomized trial on the French Reunion Island suggests that there is currently no justification for the use of chloroquine to treat acute chikungunya infections.
Abstract: In recent issues, the efficacy of chloroquine (and the dosage that may be used) in the treatment of acute chikungunya infections was discussed. We have conducted a double-blind placebo-controlled randomized trial on the French Reunion Island (Indian Ocean), in which 27 patients received chloroquine and 27 patients received a placebo treatment. The chloroquine treatment consisted of 600 mg at day 1, 600 mg at days 2 and 3, and 300 mg at days 4 and 5. No significant difference between groups could be identified regarding the duration of febrile arthralgia or the decrease of viremia between day 1 and day 3. However, at day 200, patients who received chloroquine complained more frequently of arthralgia than those who received placebo (p < 0.01). In conclusion, our results suggest that there is currently no justification for the use of chloroquine to treat acute chikungunya infections.
216 citations
TL;DR: The presence of competent Cx.
Abstract: We evaluated the ability of three mosquito species (Aedes caspius, Aedes detritus, Culex pipiens), collected in southern France and Tunisia, and of different laboratory-established colonies (Aedes aegypti, Aedes albopictus, Aedes vexans, Anopheles gambiae, Culex pipiens, Culex quinquefasciatus) to disseminate two strains of Rift Valley fever virus (RVFV), the virulent ZH548 and the avirulent Clone 13. After feeding on an infectious blood meal at 10(8.5) plaque-forming units/mL, females were maintained at 30 degrees C for 14 days. Surviving females were tested for the presence of virus on head squashes. Disseminated infection rate corresponds to the number of females with disseminated infection among surviving females. Among field-collected mosquitoes, Cx. pipiens was the most susceptible species with disseminated infection rates ranging from 3.9% to 9.1% for French strains and up to 14.7% for Tunisian strains. Among laboratory-established colonies, Ae. aegypti from Tahiti exhibited the highest disseminated infection rates: 90% when infected with ZH548 and 72.6% with Clone 13. The presence of competent Cx. pipiens in southern France and Tunisia indicates the potential for RVFV epizootics to occur if the virus was introduced into countries of the Mediterranean basin.
183 citations
TL;DR: Investigation of the seasonal prevalence, container preferences, and geographic distribution of the Ae.
Abstract: Aedes albopictus is generally considered to have a low vectorial capacity because of its lack of host specificity. Nevertheless, it has been the sole vector of the Chikungunya virus in recent explosive epidemics on the islands of La Reunion and Mauritius. We report on investigations of the seasonal prevalence, container preferences, and geographic distribution of the species on La Reunion. Ae. albopictus showed strong ecological plasticity. In the warm wet season, small disposable containers were the principal urban breeding site, with 1939 positive containers in 750 houses. In the dry winter season, the species remained abundant throughout the island up to 800 m and was present to a maximum altitude of 1200 m. Natural containers were clearly important in this season, although productive sources were hard to find. The preferred natural developmental sites were bamboo stumps and rock holes, over 357 developmental sites observed in peri-urban and gully areas. Generalized logistic models indicated that the optimum sites contained clear water with high organic content and were situated in sites with moderate shade. Our data will provide input into the models of the epidemiology of the disease and design of vector control programs.
165 citations
TL;DR: A population of 731 naturally exposed pet dogs examined at a private practice in Baxter, Minnesota, an area endemic for Lyme disease and anaplasmosis, was tested by serological and molecular methods for evidence of exposure to or infection with selected vector-borne pathogens, finding A. phagocytophilum DNA was more prevalent in suspected cases of anaplasmsosis or borreliosis than in healthy dogs from the same region.
Abstract: A population of 731 naturally exposed pet dogs examined at a private practice in Baxter, Minnesota, an area endemic for Lyme disease and anaplasmosis, was tested by serological and molecular methods for evidence of exposure to or infection with selected vector-borne pathogens. Serum samples were tested by enzyme-linked immunosorbent assay (ELISA) for Anaplasma phagocytophilum, Borrelia burgdorferi, and Ehrlichia canis antibodies and for Dirofilaria immitis antigen. Blood samples from 273 dogs were also analyzed by polymerase chain reaction (PCR) for Anaplasma and Ehrlichia species DNA. Based on the owner history and the attending veterinarian's physical examination findings, dogs exhibiting illness compatible with anaplasmosis or borreliosis were considered clinical cases, and their results were compared to the healthy dog population. Antibodies to only A. phagocytophilum were detected in 217 (29%) dogs; to only B. burgdorferi, in 80 (11%) dogs; and seroreactivity to both organisms, in 188 (25%) dogs. Of 89 suspected cases of canine anaplasmosis or borreliosis, A. phagocytophilum or B. burgdorferi antibodies were detected in 22 dogs (25%) and 8 dogs (9%) respectively, whereas antibodies to both organisms were found in 38 dogs (43%). Ehrlichia canis antibodies and D. immitis antigen were each detected in 11 (1.5%) dogs. Anaplasma phagocytophilum DNA was amplified from 7 of 222 (3%) healthy dogs and 19 of 51 (37%) clinical cases. Seroreactivity to both A. phagocytophilum and B. burgdorferi was detected more frequently in suspected cases of anaplasmosis and/or borreliosis than seroreactivity to either organism alone. Based on PCR testing, A. phagocytophilum DNA was more prevalent in suspected cases of anaplasmosis or borreliosis than in healthy dogs from the same region.
144 citations
TL;DR: It is predicted that the exacerbation of current greenhouse conditions will result in longer periods of high mosquito activity in the tropical regions where RRV and BFV are already common, and epidemics may become more frequent in those areas.
Abstract: The purpose of the present article is to present a review of the Ross River virus (RRV) and Barmah Forest virus (BFV) literature in relation to potential implications for future disease in tropical northern Australia Ross River virus infection is the most common and most widespread arboviral disease in Australia, with an average of 4,800 national notifications annually Of recent concern is the sudden rise in BFV infections; the 2005–2006 summer marked the largest BFV epidemic on record in Australia, with 1,895 notifications Although not life-threatening, infection with either virus can cause arthritis, myalgia, and fatigue for 6 months or longer, resulting in substantial morbidity and economic impact The geographic distribution of mosquito species and their seasonal activity is determined in large part by temperature and rainfall Predictive models can be useful tools in providing early warning systems for epidemics of RRV and BFV infection Various models have been developed to predict RRV outbreaks, but these appear to be mostly only regionally valid, being dependent on local ecological factors Difficulties have arisen in developing useful models for the tropical northern parts of Australia, and to date no models have been developed for the Northern Territory Only one model has been developed for predicting BFV infections using climate and tide variables It is predicted that the exacerbation of current greenhouse conditions will result in longer periods of high mosquito activity in the tropical regions where RRV and BFV are already common In addition, the endemic locations may expand further within temperate regions, and epidemics may become more frequent in those areas Further development of predictive models should benefit public health planning by providing early warning systems of RRV and BFV infection outbreaks in different geographical locations
141 citations
TL;DR: Culex modestus was found to be an extremely efficient laboratory W NV vector and could thus be considered the main WNV vector in wetlands of the Camargue, and Aedes caspius was an inefficient vector of WNV in the laboratory, and despite its high densities, its role in WNV transmission may be minor in southern France.
Abstract: To identify the mosquito species able to sustain the transmission of West Nile Virus (WNV) in the Camargue region (the main WNV focus of southern France), we assessed the vector competence of Culex...
138 citations
TL;DR: Assessment of the impact of intensive community-wide education programs on knowledge, attitudes, and behaviors to prevent Lyme disease in residents of Lyme disease endemic communities provides guidance for the development of effective Lyme disease prevention programs.
Abstract: Lyme disease, caused by the tick-transmitted bacterium Borrelia burgdorferi, is the most common vector-borne disease in the United States. We surveyed residents of three Connecticut health districts to evaluate the impact of intensive community-wide education programs on knowledge, attitudes, and behaviors to prevent Lyme disease. Overall, 84% of respondents reported that they knew a lot or some about Lyme disease, and 56% felt that they were very or somewhat likely to get Lyme disease in the coming year. During 2002-2004, the percentage of respondents who reported always performing tick checks increased by 7% and the percentage of respondents who reported always using repellents increased by 5%, whereas the percentage of respondents who reported avoiding wooded areas and tucking pants into socks decreased. Overall, 99% of respondents used personal protective behaviors to prevent Lyme disease. In comparison, 65% of respondents reported using environmental tick controls, and increased use of environmental tick controls was observed in only one health district. The majority of respondents were unwilling to spend more than $100 on tick control. These results provide guidance for the development of effective Lyme disease prevention programs by identifying measures most likely to be adopted by residents of Lyme disease endemic communities.
129 citations
TL;DR: Although POWV disease is probably under-recognized, and it causes significant morbidity, and thus is an additional tick-borne emerging infectious disease entity, the basis of prevention is personal protection from ticks and reduced exposure to peridomestic wild mammals.
Abstract: Powassan virus (POWV) disease is a rare human disease caused by a tick-borne encephalitis group flavivirus maintained in a transmission cycle between Ixodes cookei and other ixodid ticks and small ...
116 citations
International Atomic Energy Agency1, James Cook University2, University of Kentucky3, Foundation for the National Institutes of Health4, Cornell University5, University of Texas Medical Branch6, University of California, Berkeley7, Wageningen University and Research Centre8, St. Michael's GAA, Sligo9, University of Queensland10, World Health Organization11
TL;DR: In this article, a group of involved scientists present guidance to aid researchers, government authorities, and community leaders as they consider the design and implementation of field trials to assess the safety and efficacy of genetic strategies for reducing the transmission of diseases by mosquito vectors.
Abstract: THE FOLLOWING RECOMMENDATIONS represent the response of a group of involved scientists to the need for guidance to aid researchers, government authorities, and community leaders as they consider the design and implementation of field trials to assess the safety and efficacy of genetic strategies for reducing the transmission of diseases by mosquito vectors. Guidance is provided for contained (caged) field trials of genetically-engineered (GE) vector mosquitoes that are fertile and contain novel genetic constructs designed to spread through natural mosquito populations (“gene drive systems”). An effort is made to raise the practical issues that must be considered in advance of such testing, provide generalized recommendations based on currently available information, and identify “points to consider” regarding additional information that may be required in order to make informed decisions on a case-by-case basis. This guidance is intended to clarify the pathway for further assessment of the potential utility of such GE mosquitoes as a tool for the improvement of public health in disease-endemic regions. 2. FOCUS
107 citations
TL;DR: A key role for hatch-year birds is indicated in the amplification of epizootic transmission of WNV, and in increasing human infection risk by facilitating local viral amplification.
Abstract: Epizootic transmission of West Nile virus (WNV) often intensifies rapidly leading to increasing risk of human infection, but the processes underlying amplification remain poorly understood. We quan...
TL;DR: There was a strong positive relationship between increasing container diameter, container volume, and water surface area with egg numbers over both high (rainy, July) and low (cool-dry, January) dengue transmission seasons.
Abstract: We conducted a study to determine the effect of container size and location on oviposition site selection by Ae. aegypti in large outdoor field enclosures (10 x 10 x 4 m high). There was a strong positive relationship between increasing container diameter, container volume, and water surface area with egg numbers over both high (rainy, July) and low (cool-dry, January) dengue transmission seasons. Location of containers (indoors versus immediately outdoors and underneath houses) did not influence the number of eggs deposited for containers 5-32 cm in diameter in either season. No trends based on container color (black, brown, or grey) were observed. A slight trend with a greater numbers of eggs laid outdoors in the largest containers (42 cm diameter) during the dry season was observed. Three separate models were run using the mixed model procedure in SAS for each container attribute. Controlling for season, time, and date, the most important container attribute predicting total egg numbers was container volume (total capacity) explaining 88% of the variation, followed by water surface area (85%), and container diameter opening (83%). Oviposition peaked in the afternoon at 1600 hrs and 2000 hrs in the dry and rainy seasons, respectively. Few eggs were laid overnight (2000 hrs-0600 hrs). Our results indicate that physical attributes of oviposition sites, such as size, light-dark contrasts, and specular reflectance from water surfaces, play a significant role in oviposition site selection.
TL;DR: It can be suggested that cats may act as a habitual reservoir host of L. infantum infection in endemic areas and it will be important in the future to add this parasitosis to the differential diagnosis of feline infections from leishmaniasis foci in cats.
Abstract: Leishmaniasis, caused by Leishmania infantum, is an endemic zoonosis in the Mediterranean basin. Dogs are considered the major host for these parasites, as well as the main reservoir for human visceral infection. In recent years, asymptomatic infection or clinical disease caused by L. infantum in cats has been reported in several countries where zoonotic leishmaniasis is present. The aim of the present study was to perform a leishmaniasis survey in cats from an endemic focus. Twenty-three adult stray cats were surveyed by clinical examination, and peripheral blood samples for serological and molecular analysis were collected. In 7 of the 23 cats (30.4%) Leishmania DNA was detected in blood. A low level of fluorescent antibodies was detected in four serum samples. All the animals were asymptomatic. Taking into account the high rate of asymptomatic feline leishmaniasis in this survey, it can be suggested that cats may act as a habitual reservoir host of L. infantum infection in endemic areas. Furthermore, it will be important in the future to add this parasitosis to the differential diagnosis of feline infections from leishmaniasis foci in cats. Feline leishmaniasis diagnosis should be accessed by molecular tools.
TL;DR: It is shown that foci of the virus are mostly located in the northern part of China and that surveillance on TBE is not institutionalized, and data are incomplete and not appropriately communicated.
Abstract: Tick-borne encephalitis (TBE) virus is one of the most important flavivirus infections of the central nervous system in Europe and Russia, with 12,000 estimated human cases per year. At present, epidemiology is extensively analyzed in many regions of Europe and Russia, with less activity in east and southeast Asia. For China, surveillance on TBE is not institutionalized, and data are incomplete and not appropriately communicated. This review summarizes the current knowledge on TBE in China and shows that foci of the virus are mostly located in the northern part of China.
TL;DR: Three clusters were identified which provide insight into the distribution of West Nile virus vectors in an urban area which have important implications for understanding West Nileirus transmission and for control of vector-competent mosquito species.
Abstract: Heterogeneity in urban landscapes can influence the effectiveness of mosquito-borne disease control. We used remotely sensed vegetation indices to discriminate among mosquito habitats within a dens...
TL;DR: Polymerase chain reaction analysis of Amblyomma americanum adults, nymphs, and larvae from Aberdeen Proving Ground, MD (APG), revealed a very high prevalence of a spotted fever group (SFG) rickettsia, and restriction fragment length polymorphism and sequence analysis identified "Rickettsia amblyommii."
Abstract: Polymerase chain reaction analysis of Amblyomma americanum adults, nymphs, and larvae from Aberdeen Proving Ground, MD (APG), revealed a very high prevalence of a spotted fever group (SFG) rickettsia. Restriction fragment length polymorphism (RFLP) and sequence analysis identified "Rickettsia amblyommii." This organism is not yet described or well studied, and its pathogenicity is unknown; however, investigations of the organism are warranted because of its high prevalence in A. americanum. This tick is extremely abundant at military training facilities in the south, central, and Mid-Atlantic United States, and many soldiers experience multiple concurrent tick bites. Bites by R. amblyommii-infected A. americanum may account for rates of SFG rickettsia seropositivity that are higher than reported rates of Rocky Mountain spotted fever (RMSF) cases from the same location. Seroconversion to SFG rickettsia following bites of A. americanum may suggest that R. amblyommii is infectious in humans. Subclinical infection in the numerous A. americanum tick bite victims could contaminate donated blood and compromise immunodeficient recipients. Detection of R. amblyommii in questing A. americanum larvae suggests transovarial transmission. The absence of R. rickettsii, the agent of RMSF, in A. americanum may be due to transovarial interference by R. amblyommii. The likelihood of pathogen transmission by larvae is magnified by their habit of mass attack. The very small size of the larvae is also a risk factor for pathogen transmission. High R. amblyommii prevalence in populations of A. americanum presage co-infection with other A. americanum-borne pathogens. A. americanum nymphs and adults from APG were found to be co-infected with R. amblyommii and Borrelia lonestari, Ehrlichia chaffeensis and Ehrlichia ewingii, respectively, and larval pools were infected with both R. amblyommii and B. lonestari. Co-infections can compound effects and complicate diagnosis of tick-borne disease.
TL;DR: PCR analyses showed that two pools originating from Santa Luzia, a municipality near Belo Horizonte, capital of the Brazilian state of Minas Gerais, were infected with Leishmaniasis, suggesting that Lu.
Abstract: In Brazil, Leishmania transmission involves several species of phlebotomine sand flies that are closely associated with different parasites and reservoirs, giving rise to different transmission cycles. The present study focused on naturally infected phlebotomines originating from Santa Luzia, a municipality near Belo Horizonte, capital of the Brazilian state of Minas Gerais, in which leishmaniasis are endemic. Systematic and non systematic approaches,involving the use of light traps and direct aspiration from resting sites, respectively, were used to collect females and flies. Identification of the captured insects and determination of natural infection by Leishmania spp. were performed using both conventional dissection methods and polymerase chain reaction (PCR). The dissection of 102 sand flies allowed five species of Lutzomyia to be identified, although no flagellate parasite forms were observed.In addition, 211 sand flies were identified, were separated according to species, and were combined into 11 pools of up to 20 individuals each. PCR analyses showed that two of these pools were infected with Leishmania:one pool of Lu. whitmani was infected with Le. (Viannia) spp. and another of Lu. cortelezzii was infected with Le. chagasi. This suggests that Lu. whitmani may be a possible vector of Leishmania in the study area, and more work needs to be performed to assess the role of Lu. cortelezzii as a vector.
TL;DR: A total of 691 questing adult ixodid ticks of the genera Ixodes, Haemaphysalis, Dermacentor, and Rhipicephalus were tested by polymerase chain reaction (PCR) and reverse line blot (RLB) for the presence of Anaplasma phagocytophilum, Coxiella burnetii, Borrelia spp.
Abstract: A total of 691 questing adult ixodid ticks of the genera Ixodes, Haemaphysalis, Dermacentor, and Rhipicephalus were tested by polymerase chain reaction (PCR) and reverse line blot (RLB) for the pre...
TL;DR: The possible occurrence of tick-borne encephalitis in Korea is suggested, and the E genes of the TBEV isolates were clustered with the Western subtype (98% identity).
Abstract: To determine whether the tick-borne encephalitis virus (TBEV) is present in vector ticks and mammalian hosts in Korea, we examined two tick species, Haemaphysalis longicornis (n = 548) and Ixodes n...
TL;DR: The combination of a dilution effect, a possible threshold density that depends on local conditions, and a higher fragmentation of suitable bank vole habitat in the study area are regarded as plausible explanations for the sparse occurrence of PUUV infection and low prevalence detected.
Abstract: In this study, the distribution of Puumala hantavirus (PUUV) infection in local bank vole Myodes glareolus populations in an area with low human PUUV infection (nephropathia epidemica [NE]) incidence in northern Belgium was monitored for 2 consecutive years. Bank voles were trapped in preferred habitat and tested for anti-PUUV IgG. Infection data were related to individual bank vole features, population demography, and environmental variables. Rare occurrence of PUUV infection was found and PUUV prevalence was low compared with data from the high NE incidence area in southern Belgium. Small-scale climatic differences seemed to play a role in PUUV occurrence, vegetation index and deciduous forest patch size both influenced PUUV prevalence and number of infected voles in a positive way. The data suggested a density threshold in vole populations below which PUUV infection does not occur. This threshold may vary between years, but the abundance of bank voles does not seem to affect the degree of PUUV seroprevalence further. We found indications for a dilution effect on PUUV prevalence, dependent on the relative proportion of nonhost wood mice Apodemus sylvaticus in a study site. In conclusion, we regard the combination of a dilution effect, a possible threshold density that depends on local conditions, and a higher fragmentation of suitable bank vole habitat in our study area as plausible explanations for the sparse occurrence of PUUV infection and low prevalence detected. Thus, beside human activity patterns, local environmental conditions and rodent community structure are also likely to play a role in determining PUUV infection risk for humans.
TL;DR: It is determined that the absence of the PM has no effect on the development of Brugia pahangi or on the dissemination of dengue virus, and the PM seems to localize proteolytic enzymes along the periphery of the blood bolus during the first 24 hours after blood feeding.
Abstract: In addition to modulating blood meal digestion and protecting the midgut epithelial cells from mechanical and chemical damage, a biological function attributed to the mosquito type I peritrophic matrix (PM) is preventing or reducing pathogen invasion, especially from Plasmodium spp. Previously, we demonstrated that chitin is an essential component of the PM and is synthesized de novo in response to blood feeding in Aedes aegypti. Therefore, knocking down chitin synthase expression by RNA interference severely disrupts formation of the PM. Utilizing this artificial manipulation, we determined that the absence of the PM has no effect on the development of Brugia pahangi or on the dissemination of dengue virus. However, infectivity of Plasmodium gallinaceum is lower, as measured by oocyst intensity, when the PM is absent. Our findings also suggest that the PM seems to localize proteolytic enzymes along the periphery of the blood bolus during the first 24 hours after blood feeding. Finally, the absence of the PM does not affect reproductive fitness, as measured by the number and viability of eggs oviposited.
TL;DR: It seems that the risk for introduction of strains of WNV from Africa by migratory birds merits further field and experimental studies in Spain, as seroprevalences assessed in resident birds suggest a low level of W NV circulation in the studied locality.
Abstract: West Nile virus (WNV) is a bird flavivirus capable of infecting horses and humans that is transmitted by blood-sucking vectors. In Europe and Africa, sporadic infections and outbreaks causing human illness and deaths have occurred and have led to 2 mutually nonexclusive hypotheses regarding the circulation of WNV in Europe: (1) the occurrence of endemic sylvatic cycles that occasionally result in human or equine infection, or (2) sporadic seeding of WNV by migratory birds from areas where the virus is endemic in Africa or elsewhere that cause local epizootic foci and eventually lead to infection in humans. To investigate these 2 possibilities, we used a micro virus-neutralization test to examine the prevalence of WNV neutralizing antibodies in 574 individuals belonging to 25 species of birds captured in spring 2004 in Seville (southern Spain). Trans-Saharan migrant species had both higher prevalences and antibody titers than resident and short-distance migrants. This result suggests that trans-Saharan migrants spend part of their life cycles in areas with greater circulation of WNV, or a closely related flavivirus, before their arrival in Spain. On the other hand, seroprevalences assessed in resident birds suggest a low level of WNV circulation in the studied locality. Aside from the question of local circulation, it thus seems that the risk for introduction of strains of WNV from Africa by migratory birds merits further field and experimental studies in Spain.
TL;DR: Jamestown Canyon virus was widely distributed throughout Connecticut and found to consistently circulate in a diverse array of mosquito vectors, and overall virus activity was directly related to local mosquito abundance.
Abstract: Jamestown Canyon virus (JCV) (Bunyaviridae: Orthobunyavirus) is a mosquito-borne zoonosis belonging to the California serogroup. It has a wide geographic distribution, occurring throughout much of ...
TL;DR: The results indicate that WNV activity in southern Moravia was limited during 2004-2006, and 13 of 391 wild birds had specific antibodies to WNV.
Abstract: A serosurvey for West Nile virus (WNV) was carried out in 54 domestic birds (geese and ducks bred on fishponds) and 391 wild birds representing 28 migratory and resident species, using a plaque-reduction neutralization microtest with Vero cells and Egyptian topotype Eg-101 strain as test virus. The birds were sampled in the South-Moravian fishpond ecosystem between 2004 and 2006. Antibodies to WNV were not detected in domestic waterfowl, but 23 (5.9%) free-living birds of 10 species showed a positive response. These were the common coot (Fulica atra, 5 positive/18 examined), common kingfisher (Alcedo atthis, 1/1), reed warbler (Acrocephalus scirpaceus, 2/80), sedge warbler (A. schoenobaenus, 3/80), marsh warbler (A. palustris, 2/28), Savi's warbler (Locustella luscinioides, 3/12), reed bunting (Emberiza schoeniclus, 1/28), blackcap (Sylvia atricapilla, 2/11), penduline tit (Remiz pendulinus, 1/14), blue tit (Parus caeruleus, 1/1), and starling (Sturnus vulgaris, 2/4). The antibody titers were comparativel...
TL;DR: If added to the figures obtained via routine passive surveillance, the number of leptospirosis infections identified through this study would more than double the annual incidence rate for Hawaii during 2001, indicating that many leptosphereiral infections in Hawaii go undiagnosed.
Abstract: During the 10-year period from 1997 through 2006, the reported mean annual incidence rate of leptospirosis in the state of Hawaii was 3.3/100,000 with a range of 22–60 infections reported each year. Because the clinical presentation is highly variable, however, leptospirosis illness is challenging to recognize and may be underdiagnosed. To assess whether the incidence may be substantially higher than reported figures indicate, we retrospectively studied the prevalence of anti-Leptospira IgM antibodies among specimens obtained over a 12-month period (May 2001 to April 2002) from patients presenting with febrile illness during a dengue fever outbreak in Hawaii. Of 1206 patients testing negative or indeterminate for dengue, 54 (4.5%; 95% confidence interval: 3.3%–5.7%) were positive for anti-Leptospira IgM antibodies using a commercially available dipstick enzyme-linked immunosorbent assay (ELISA). The most common clinical symptoms reported by laboratory-positive leptospirosis patients were fever (92%), headache (88%), and myalgia (83%). Three clinical symptoms were significantly less common among persons laboratory positive for leptospirosis when compared with the 122 patients who had been diagnosed with dengue fever during the outbreak: rash (p < 0.0001), chills (p = 0.05), and petechiae (p = 0.0005). Laboratory-positive leptospirosis infections were identified in persons exposed on each of the 5 most populous islands and illness onsets spanned a 10-month period, reflecting an endemic pattern of disease. If added to the figures obtained via routine passive surveillance, the number of leptospirosis infections identified through this study would more than double the annual incidence rate for Hawaii during 2001. These findings indicate that many leptospiral infections in Hawaii go undiagnosed. Physicians should maintain a high index of suspicion for leptospirosis when assessing patients presenting with acute febrile illness among residents and visitors to Hawaii.
TL;DR: It is suggested that living in a cattle-raising region appears to imply risk not only for STEC O157, but also for most non-O157 serogroups, and risk profiles for human STEC infection may be serogroup-specific.
Abstract: Shiga toxin-producing Escherichia coli (STEC) cause severe gastroenteritis and life-threatening hemolytic-uremic syndrome. For STEC of serogroup O157, association between disease incidence and catt...
TL;DR: The risk of WNND appears to be highest in areas where the primary WNV vectors are Culex tarsalis and Cx.
Abstract: As the geographic range of reported human West Nile virus (WNV) disease has expanded across the United States, seasonal transmission and outbreaks have persisted over several years in many areas of the country. West Nile virus neuroinvasive disease (WNND) case reports from 2002 to 2006 were reviewed to determine which areas of the country have the highest reported cumulative incidence and whether those areas have had consistently high annual incidence. During the 5-year period examined, 9632 cases of WNND were reported nationwide. The cumulative incidence of WNND ranged from 0.2 to 32.2 per 100,000 population by state and from 0.1 to 241.2 per 100,000 population by county. States and counties with the highest cumulative incidence were primarily located in the northern Great Plains. States with consistently high annual incidence included South Dakota, North Dakota, Wyoming, New Mexico, Mississippi, Nebraska, Louisiana, and Colorado. All of these states, with the exception of New Mexico, were also among the...
TL;DR: The causal organisms associated withsuch zoonoses, a description of previous outbreaks at farms and zoos, as well as infection control measures to help prevent such zoonotic infections are outlined.
Abstract: The popularity of open farms and petting zoos has increased markedly over the last 5 years, with most children in developed countries now having the opportunity to visit such a facility at some stage in their childhood, either through school or family visits. The open access policy of these establishments allows visitors to be in direct contact with animals such as sheep (lambs), goats, cats (kittens), dogs (puppies), and birds and to have the opportunity to feed such animals. This contact may lead to the transmission of microbial pathogens from animals to humans, e.g., Escherichia coli O157:H7, resulting in human disease. This review outlines the causal organisms associated with such zoonoses, a description of previous outbreaks at farms and zoos, as well as infection control measures to help prevent such zoonotic infections.
TL;DR: The hypothesis that this animal may be an abundant source of infection for ticks that transmit Acanthocheilonema parasites and for mosquitoes that act as vectors for dirofilarial nematodes is supported.
Abstract: Foxes (Vulpes vulpes, n = 132) killed during the hunting seasons 2005-2006 in Central Italy (Tuscany region) were examined in order to investigate the possible importance of this animal as a wild reservoir for zoonotic filariae. In each specimen adult worms of Dirofilaria immitis and hematic microfilariae were searched for. Species identification was performed by morphology, morphometry, the Barka staining technique applied to pulmonary and splenic blood smears, and, finally, by molecular diagnostics -- polymerase chain reaction (PCR) and sequencing. Twenty-three subjects (17.4%) proved to be positive for filarial parasites. Infection by Acanthocheilonema was more widespread than by Dirofilaria. Briefly, 8 foxes harbored mature adults of D. immitis; two of them (25%) also had microfilariae that in one case were mixed with the microfilariae of D. repens. Twelve subjects had microfilariae of Acanthocheilonema reconditum, and 3 harbored microfilariae of A. dracunculoides. Molecular diagnostics confirmed all results. Our findings, drawn by the examination of a few microliters of blood obtained from foxes approximately <2 years of age, support the hypothesis that this animal may be an abundant source of infection for ticks that transmit Acanthocheilonema parasites and for mosquitoes that act as vectors for dirofilarial nematodes. Therefore foxes, contributing to the parasite circulation in areas where dogs usually undergo prophylactic treatment, have to be considered an important wild reservoir for filarial parasites that can be transmitted to companion animals and people.
TL;DR: An empirical model to forecast West Nile virus mosquito vector populations is developed using time series analysis techniques and the most significant meteorological variables for forecasting Aedes vexans abundance were the interactive C(DD_65) x P(week_4) variable at a lag of two weeks and the cumulative maximum ponding index (I(Pcum) at alag of zero weeks.
Abstract: An empirical model to forecast West Nile virus mosquito vector populations is developed using time series analysis techniques. Specifically, multivariate seasonal autoregressive integrated moving average (SARIMA) models were developed for Aedes vexans and the combined group of Culex pipiens and Culex restuans in Erie County, New York. Weekly mosquito collections data were obtained for the four mosquito seasons from 2002 to 2005 from the Erie County Department of Health, Vector and Pest Control Program. Climate variables were tested for significance with cross-correlation analysis. Minimum temperature (Tmin), maximum temperature (Tmax), average temperature (Tave), precipitation (P), relative humidity (RH), and evapotranspiration (ET) were acquired from the Northeast Regional Climate Center (NRCC) at Cornell University. Weekly averages or sums of climate variables were calculated from the daily data. Other climate indexes were calculated and were tested for significance with the mosquito population data, in...