Statistical modeling based on structured surveys of Australian native possum excreta harboring Mycobacterium ulcerans predicts Buruli ulcer occurrence in humans

Background

Buruli ulcer (BU) is a neglected tropical disease caused by infection of subcutaneous tissue with Mycobacterium ulcerans. BU is commonly reported across rural regions of Central and West Africa but has been increasing dramatically in temperate southeast Australia around the major metropolitan city of Melbourne, with most disease transmission occurring in the summer months. Previous research has shown that Australian native possums are reservoirs of M. ulcerans and that they shed the bacteria in their fecal material (excreta). Field surveys show that locales where possums harbor M. ulcerans overlap with human cases of BU, raising the possibility of using possum excreta surveys to predict the risk of disease occurrence in humans.

Methods

We thus established a highly structured 12 month possum excreta surveillance program across an area of 350 km2 in the Mornington Peninsula area 70 km south of Melbourne, Australia. The primary objective of our study was to assess using statistical modeling if M. ulcerans surveillance of possum excreta provided useful information for predicting future human BU case locations.

Results

Over two sampling campaigns in summer and winter, we collected 2,282 possum excreta specimens of which 11% were PCR positive for M. ulcerans-specific DNA. Using the spatial scanning statistical tool SaTScan, we observed non-random, co-correlated clustering of both M. ulcerans positive possum excreta and human BU cases. We next trained a statistical model with the Mornington Peninsula excreta survey data to predict the future likelihood of human BU cases occurring in the region. By observing where human BU cases subsequently occurred, we show that the excreta model performance was superior to a null model trained using the previous year's human BU case incidence data (AUC 0.66 vs 0.55). We then used data unseen by the excreta-informed model from a new survey of 661 possum excreta specimens in Geelong, a geographically separate BU endemic area to the southwest of Melbourne, to prospectively predict the location of human BU cases in that region. As for the Mornington Peninsula, the excreta-based BU prediction model outperformed the null model (AUC 0.75 vs 0.50) and pinpointed specific locations in Geelong where interventions could be deployed to interrupt disease spread.

Conclusions

This study highlights the One Health nature of BU by confirming a quantitative relationship between possum excreta shedding of M. ulcerans and humans developing BU. The excreta survey-informed modeling we have described will be a powerful tool for the efficient targeting of public health responses to stop BU.

Funding

This research was supported by the National Health and Medical Research Council of Australia and the Victorian Government Department of Health (GNT1152807 and GNT1196396).

Understanding the prevalence of SARS-CoV-2 (COVID-19) exposure in companion, captive, wild, and farmed animals

Several animal species, including ferrets, hamsters, monkeys, and raccoon dogs, have been shown to be susceptible to experimental infection by the human severe acute respiratory syndrome coronaviruses, such as SARS-CoV and SARS-CoV-2, which were responsible for the 2003 SARS outbreak and the 2019 coronavirus disease (COVID-19) pandemic, respectively. Emerging studies have shown that SARS-CoV-2 natural infection of pet dogs and cats is also possible, but its prevalence is not fully understood. Experimentally, it has been demonstrated that SARS-CoV-2 replicates more efficiently in cats than in dogs and that cats can transmit the virus through aerosols. With approximately 470 million pet dogs and 370 million pet cats cohabitating with their human owners worldwide, the finding of natural SARS-CoV-2 infection in these household pets has important implications for potential zoonotic transmission events during the COVID-19 pandemic as well as future SARS-related outbreaks. Here, we describe some of the ongoing worldwide surveillance efforts to assess the prevalence of SARS-CoV-2 exposure in companion, captive, wild, and farmed animals, as well as provide some perspectives on these efforts including the intra- and inter-species coronavirus transmissions, evolution, and their implications on the human-animal interface along with public health. Some ongoing efforts to develop and implement a new COVID-19 vaccine for animals are also discussed. Surveillance initiatives to track SARS-CoV-2 exposures in animals are necessary to accurately determine their impact on veterinary and human health, as well as define potential reservoir sources of the virus and its evolutionary and transmission dynamics.

Epidemiology of leptospirosis in Tanzania: A review of the current status, serogroup diversity and reservoirs

Background

Tanzania is among the tropical countries of Sub-Saharan Africa with the environmental conditions favorable for transmission of Leptospira. Leptospirosis is a neglected zoonotic disease, and although there are several published reports from Tanzania, the epidemiology, genetic diversity of Leptospira and its host range are poorly understood.

Methods

We conducted a comprehensive review of human and animal leptospirosis within the 26 regions of the Tanzanian mainland. Literature searches for the review were conducted in PubMed and Google Scholar. We further manually identified studies from reference lists among retrieved studies from the preliminary search.

Results

We identified thirty-four studies describing leptospirosis in humans (n = 16), animals (n = 14) and in both (n = 4). The number of studies varied significantly across regions. Most of the studies were conducted in Morogoro (n = 16) followed by Kilimanjaro (n = 9) and Tanga (n = 5). There were a range of study designs with cross-sectional prevalence studies (n = 18), studies on leptospirosis in febrile patients (n = 13), a case control study in cattle (n = 1) and studies identifying novel serovars (n = 2). The most utilized diagnostic tool was the microscopic agglutination test (MAT) which detected antibodies to 17 Leptospira serogroups in humans and animals. The Leptospira serogroups with the most diverse hosts were Icterohaemorrhagiae (n = 11), Grippotyphosa (n = 10), Sejroe (n = 10), Pomona (n = 9) and Ballum (n = 8). The reported prevalence of Leptospira antibodies in humans ranged from 0.3–29.9% and risk factors were associated with occupational animal contact. Many potential reservoir hosts were identified with the most common being rodents and cattle.

Conclusion

Leptospirosis is prevalent in humans and animals in Tanzania, although there is regional and host variation in the reports. Many regions do not have information about the disease in either humans or their animal reservoirs. More studies are required to understand human leptospirosis determinants and the role of livestock in leptospirosis transmission to humans for the development of appropriate control strategies.

Bacteria from the genus Leptospira is an important agent for causing a disease called leptospirosis in humans and a range of animal species. Leptospirosis is often under-recognized as it presents varied symptoms that mimic malaria, typhoid, brucellosis and other diseases. More than 250 pathogenic Leptospira serovars are known to cause leptospirosis in humans and animals. The diversity of Leptospira serovars and their distribution in humans and animals is little defined in Tanzania. We conducted a systematic review to gather information on the diversity of Leptospira serovars with their reservoir distribution and the most common diagnostics methods used. We included studies (n = 34) in the review and found 17 serogroups described in 28 studies that utilized microscopic agglutination test (MAT). So far human and other animal hosts including cattle, dogs, pigs, bats, buffalo, fish, rodents, goats, lion, zebra, sheep and shrews have been investigated for leptospirosis in Tanzania. Our results show that cattle and rodents are likely to be important reservoirs of pathogenic Leptospira spp. and can be a source of human leptospirosis principally in the farming system. Further studies are needed to explore predominant serovars in livestock for the development of prevention strategies to reduce transmission and risks in humans.

How accurately can we assess zoonotic risk?

Identifying the animal reservoirs from which zoonotic viruses will likely emerge is central to understanding the determinants of disease emergence. Accordingly, there has been an increase in studies attempting zoonotic “risk assessment.” Herein, we demonstrate that the virological data on which these analyses are conducted are incomplete, biased, and rapidly changing with ongoing virus discovery. Together, these shortcomings suggest that attempts to assess zoonotic risk using available virological data are likely to be inaccurate and largely only identify those host taxa that have been studied most extensively. We suggest that virus surveillance at the human–animal interface may be more productive.

Determining which organisms harbour viruses that could potentially infect humans is of great topical interest. This Essay demonstrates that the data on which such zoonotic risk assessments are conducted are incomplete, biased, and rapidly changing with ongoing virus discovery.

Why Lyme disease is common in the northern US, but rare in the south: The roles of host choice, host-seeking behavior, and tick density

Lyme disease is common in the northeastern United States, but rare in the southeast, even though the tick vector is found in both regions. Infection prevalence of Lyme spirochetes in host-seeking ticks, an important component to the risk of Lyme disease, is also high in the northeast and northern midwest, but declines sharply in the south. As ticks must acquire Lyme spirochetes from infected vertebrate hosts, the role of wildlife species composition on Lyme disease risk has been a topic of lively academic discussion. We compared tick–vertebrate host interactions using standardized sampling methods among 8 sites scattered throughout the eastern US. Geographical trends in diversity of tick hosts are gradual and do not match the sharp decline in prevalence at southern sites, but tick–host associations show a clear shift from mammals in the north to reptiles in the south. Tick infection prevalence declines north to south largely because of high tick infestation of efficient spirochete reservoir hosts (rodents and shrews) in the north but not in the south. Minimal infestation of small mammals in the south results from strong selective attachment to lizards such as skinks (which are inefficient reservoirs for Lyme spirochetes) in the southern states. Selective host choice, along with latitudinal differences in tick host-seeking behavior and variations in tick densities, explains the geographic pattern of Lyme disease in the eastern US.

Lyme disease is common in the northeastern United States, but rare in the southeast, even though the tick vector is found in both regions. This study shows that this is largely because the tick vectors attach abundantly to rodents (which are good hosts for the Lyme bacteria) in the north, and to lizards (which are relatively poor hosts for Lyme bacteria) in the south.

Association between the proportion of Plasmodium falciparum and Plasmodium vivax infections detected by passive surveillance and the magnitude of the asymptomatic reservoir in the community: a pooled analysis of paired health facility and community data

BACKGROUND

Passively collected malaria case data are the foundation for public health decision making. However, because of population-level immunity, infections might not always be sufficiently symptomatic to prompt individuals to seek care. Understanding the proportion of all Plasmodium spp infections expected to be detected by the health system becomes particularly paramount in elimination settings. The aim of this study was to determine the association between the proportion of infections detected and transmission intensity for Plasmodium falciparum and Plasmodium vivax in several global endemic settings.

METHODS

The proportion of infections detected in routine malaria data, P(Detect), was derived from paired household cross-sectional survey and routinely collected malaria data within health facilities. P(Detect) was estimated using a Bayesian model in 431 clusters spanning the Americas, Africa, and Asia. The association between P(Detect) and malaria prevalence was assessed using log-linear regression models. Changes in P(Detect) over time were evaluated using data from 13 timepoints over 2 years from The Gambia.

FINDINGS

The median estimated P(Detect) across all clusters was 12·5% (IQR 5·3-25·0) for P falciparum and 10·1% (5·0-18·3) for P vivax and decreased as the estimated log-PCR community prevalence increased (adjusted odds ratio [OR] for P falciparum 0·63, 95% CI 0·57-0·69; adjusted OR for P vivax 0·52, 0·47-0·57). Factors associated with increasing P(Detect) included smaller catchment population size, high transmission season, improved care-seeking behaviour by infected individuals, and recent increases (within the previous year) in transmission intensity.

INTERPRETATION

The proportion of all infections detected within health systems increases once transmission intensity is sufficiently low. The likely explanation for P falciparum is that reduced exposure to infection leads to lower levels of protective immunity in the population, increasing the likelihood that infected individuals will become symptomatic and seek care. These factors might also be true for P vivax but a better understanding of the transmission biology is needed to attribute likely reasons for the observed trend. In low transmission and pre-elimination settings, enhancing access to care and improvements in care-seeking behaviour of infected individuals will lead to an increased proportion of infections detected in the community and might contribute to accelerating the interruption of transmission.

FUNDING

Wellcome Trust.

School-age Children as Asymptomatic Malaria Reservoir in Tribal Villages of Bastar Region, Chhattisgarh

Malaria is a major health concern in India, especially in regions populated by tribals. In this cross-sectional survey carried out in Bastar region of Chhattisgarh, 35 Plasmodium infections were detected in 451 participants screened during the non-transmission season; 27 (77.1%) were asymptomatic. Participants with age 6-14 years were at high risk of asymptomatic infection [OR 4.09, 95% CI, 1.69 to 9.89, P=0.001], and may act as an under-appreciated reservoir for sustained malaria transmission.

Emergency Department Environmental Contamination With Methicillin-Resistant Staphylococcus aureus After Care of Colonized Patients

STUDY OBJECTIVE

Methicillin-resistant Staphylococcus aureus (MRSA) transmission dynamics in the emergency department (ED) are not well defined; environmental surfaces may serve as reservoirs for transmission. This study investigates the effect of patients with a history of MRSA colonization or infection on subsequent MRSA contamination of the ED environment.

METHODS

Adult ED patients with evidence of an MRSA-positive surveillance result or clinical microbiologic culture in the year preceding their current ED visit were enrolled. Cultures from 5 anatomic sites were obtained to detect active MRSA colonization. After patients' discharge and before environmental disinfection, up to 16 prespecified surfaces in their ED rooms were cultured. Strain typing was performed by repetitive-sequence polymerase chain reaction on all recovered MRSA isolates to determine concordance with the corresponding patient strain.

RESULTS

Of 42 patients enrolled, 25 (60%) remained colonized with MRSA. Nineteen of the 25 ED rooms (76%) occupied by MRSA-colonized patients contained greater than or equal to 1 MRSA-contaminated environmental surface on patient discharge. Surfaces were more likely to be contaminated when rooms were occupied by patients colonized with MRSA at 1 body site (odds ratio 11.7; 95% confidence interval 1.5 to 91.5) and greater than or equal to 2 body sites (odds ratio 16.3; 95% confidence interval 3.1 to 86.8) compared with noncolonized patients. In 16 of the 19 ED rooms (84%) where MRSA was recovered, all environmental strains were concordant with the corresponding patient strain.

CONCLUSION

Contamination of the ED environment with MRSA from actively colonized patients is common. Improved environmental surface disinfection may help reduce transmission of MRSA to ED health care professionals and patients during emergency care.

A case-crossover analysis of the impact of weather on primary cases of Middle East respiratory syndrome

BACKGROUND

Middle East respiratory syndrome coronavirus (MERS-CoV) is endemic in dromedary camels in the Arabian Peninsula, and zoonotic transmission to people is a sporadic event. In the absence of epidemiological data on the reservoir species, patterns of zoonotic transmission have largely been approximated from primary human cases. This study aimed to identify meteorological factors that may increase the risk of primary MERS infections in humans.

METHODS

A case-crossover design was used to identify associations between primary MERS cases and preceding weather conditions within the 2-week incubation period in Saudi Arabia using univariable conditional logistic regression. Cases with symptom onset between January 2015 - December 2017 were obtained from a publicly available line list of human MERS cases maintained by the World Health Organization. The complete case dataset (N = 1191) was reduced to approximate the cases most likely to represent spillover transmission from camels (N = 446). Data from meteorological stations closest to the largest city in each province were used to calculate the daily mean, minimum, and maximum temperature (^οC), relative humidity (%), wind speed (m/s), and visibility (m). Weather variables were categorized according to strata; temperature and humidity into tertiles, and visibility and wind speed into halves.

RESULTS

Lowest temperature (Odds Ratio = 1.27; 95% Confidence Interval = 1.04-1.56) and humidity (OR = 1.35; 95% CI = 1.10-1.65) were associated with increased cases 8-10 days later. High visibility was associated with an increased number of cases 7 days later (OR = 1.26; 95% CI = 1.01-1.57), while wind speed also showed statistically significant associations with cases 5-6 days later.

CONCLUSIONS

Results suggest that primary MERS human cases in Saudi Arabia are more likely to occur when conditions are relatively cold and dry. This is similar to seasonal patterns that have been described for other respiratory diseases in temperate climates. It was hypothesized that low visibility would be positively associated with primary cases of MERS, however the opposite relationship was seen. This may reflect behavioural changes in different weather conditions. This analysis provides key initial evidence of an environmental component contributing to the development of primary MERS-CoV infections.

Plant Phenology Supports the Multi-emergence Hypothesis for Ebola Spillover Events

Ebola virus disease outbreaks in animals (including humans and great apes) start with sporadic host switches from unknown reservoir species. The factors leading to such spillover events are little explored. Filoviridae viruses have a wide range of natural hosts and are unstable once outside hosts. Spillover events, which involve the physical transfer of viral particles across species, could therefore be directly promoted by conditions of host ecology and environment. In this report, we outline a proof of concept that temporal fluctuations of a set of ecological and environmental variables describing the dynamics of the host ecosystem are able to predict such events of Ebola virus spillover to humans and animals. We compiled a data set of climate and plant phenology variables and Ebola virus disease spillovers in humans and animals. We identified critical biotic and abiotic conditions for spillovers via multiple regression and neural network-based time series regression. Phenology variables proved to be overall better predictors than climate variables. African phenology variables are not yet available as a comprehensive online resource. Given the likely importance of phenology for forecasting the likelihood of future Ebola spillover events, our results highlight the need for cost-effective transect surveys to supply phenology data for predictive modelling efforts.

Measles outbreak propagated by children congregating at water collection points in Mayuge District, eastern Uganda, July - October, 2016

BACKGROUND

On 12 October, 2016 a measles outbreak was reported in Mayuge District, eastern Uganda. We investigated the outbreak to determine its scope, identify risk factors for transmission, evaluate vaccination coverage and vaccine effectiveness, and recommend evidence-based control measures.

METHODS

We defined a probable case as onset of fever (≥3 days) and generalized rash, plus ≥1 of the following: conjunctivitis, cough, and/or runny nose in a Mayuge District resident. A confirmed case was a probable case with measles-specific IgM (+) not explained by vaccination. We reviewed medical records and conducted active community case-finding. In a case-control investigation involving probable case-persons and controls matched by age and village, we evaluated risk factors for transmission for both cases and controls during the case-person's likely exposure period (i.e., 7-21 days prior to rash onset). We estimated vaccine effectiveness (VE) using the formula: VE ≈ (1-ORprotective) × 100. We calculated vaccination coverage using the percentage of controls vaccinated.

RESULTS

We identified 62 probable case-persons (attack rate [AR] = 4.0/10,000), including 3 confirmed. Of all age groups, children < 5 years were the most affected (AR = 14/10,000). The epidemic curve showed a propagated outbreak. Thirty-two percent (13/41) of case-persons and 13% (21/161) of control-persons visited water-collection sites (by themselves or with parents) during the case-persons' likely exposure period (ORM-H = 5.0; 95% CI = 1.5-17). Among children aged 9-59 months, the effectiveness of the single-dose measles vaccine was 75% (95% CI = 25-92); vaccination coverage was 68% (95% CI = 61-76).

CONCLUSIONS

Low vaccine effectiveness, inadequate vaccination coverage and congregation at water collection points facilitated measles transmission in this outbreak. We recommended increasing measles vaccination coverage and restriction of children with signs and symptoms of measles from accessing public gatherings.

[Oncomelania hupensis status in national schistosomiasis surveillance sites of Yunnan Province from 2015 to 2017]

OBJECTIVE

To master the Oncomelania hupensis distribution and infection status in the national schistosomiasis surveillance sites of Yunnan Province, so as to provide the evidence for making the control and prevention measures.

METHODS

The data of O. hupensis surveillance in the 18 national surveillance sites of Yunnan Province from 2015 to 2017 were collected and analyzed with the descriptive analysis method according to the national schistosomiasis surveillance programme.

RESULTS

The total surveillance area was 5 710.94 hm², the area with O. hupensis snails was 205.69 hm². The number of surveillance frames was 2 094 553, the occurrence rate of frames with snails was 0.62%, and the density of living snails was 0.025 4 snails/0.1 m². In the schistosomiasis epidemic controlled areas, the area with snails, the occurrence rate of frames with snails and the density of living snails were all the highest. The snail concentrated distribution areas were the small reservoir, bottomland, paddy field, ditch, and dry land, and the snails mainly distributed in the rice, dry crop, weed and wood vegetation. The number of frames with snails, occurrence rate of frames with snails, total number of snails, number of living snails, and repetition areas with snails presented increasing trends, and however, no schistosome-infected snails were found during the three years.

CONCLUSIONS

The O. hupensis snail status is obviously serious in the national schistosomiasis surveillance sites of Yunnan Province. The comprehensive snail control measures should continue to be strengthened, so as to effectively control the spread of the snails and reduce the risk of schistosomiasis outbreaks.

[Current Distribution and Bioecological Characterizations of Aedes aegypti and Aedes albopictus in Brazzaville]

Aedes aegypti is a mosquito that has been known in Congo for decades. It has always been involved in the transmission of some arboviruses. Ae. albopictus is an invasive species native from Asia. Its presence was reported in Congo in 2009. The proliferation of Ae. albopictus, especially in Brazzaville, in association with Ae. aegypti, have increased the risk of arbovirus transmission. The distribution and bio-ecology of these two species remain poorly studied. We undertook entomological investigations to determine the bio-ecological factors that may influence the abundance and distribution of the two species in two districts of Brazzaville. Collection of immature stages was carried out during the survey of breeding sites. In addition, adults were captured twice a day (morning and evening) during 8 collection sessions in dwellings. The results show that both species have the same distribution and share the same ecological sites. Their activity is essentially diurnal with nocturnal intrusion. They are more exophagous than endophagous. Domestic and peri-domestic sites, especially tires and water storage containers, are the most productive breeding sites. The biting activity has two peaks: one at the end of morning and the other at the end of afternoon. Both species have been observed in all areas visited and the larval index values are above WHO standards indicating a high epidemic risk. Aedes albopictus is the predominant species.

Epidemiology of Malaria in the city of Kaedi (Mauritania, 2014)

BACKGROUND

In the face of ongoing and projected environmental and climate change, the epidemiology of malaria in the city of Kaédi (Mauritania), bordering the Senegal River Valley, requires special attention.

OBJECTIVE

To describe the epidemiological situation of malaria in the city of Kaédi, Mauritania, during the wet season of 2014.

METHODS

We conducted a descriptive cross-sectional survey in the city of Kaédi in september 2014 (wet season), to assess the prevalence of malaria parasites and vectors. For the choice of households, a cluster sampling was carried out and the city was subdivided into 10 sub-spatial units using a map of the city and the contribution of local populations. All household members were subjected to microscopic examination. In addition, larval surveys, morning wildlife sprays and night trap breaks were conducted.

RESULTS

Of the 4671 thick drops made, three were positive, ie an average plasmid index of 0.06%. Prevalence was 0.04% (2/4671) and 0.02% (1/4671) for Plasmodium malariae and Plasmodium falciparum, respectively. In addition, the larval fauna consisted essentially of Culex larvae (100%). Two (2) female Anopheles mosquitoes were collected during the study.

CONCLUSION

Even if transmission is low, in a context of absence of rainfall, the health authorities must foresee a strategy of malaria pre-elimination in riparian wilayas of the Senegal River.

[Emerging infectious diseases: complex, unpredictable processes]

In the light of a double approach, at first empirical, later theoretical and comparative, illustrated by the example of the Buruli ulcer and its mycobacterial agent Mycobacterium ulcerans on which I focused my research activity these last ten years by studying determinants and factors of emerging infectious or parasitic diseases, the complexity of events explaining emerging diseases will be presented. The cascade of events occurring at various levels of spatiotemporal scales and organization of life, which lead to the numerous observed emergences, nowadays requires better taking into account the interactions between host(s), pathogen(s) and the environment by including the behavior of both individuals and the population. In numerous research studies on emerging infectious diseases, microbial hazard is described rather than infectious disease risk, the latter resulting from the confrontation between an association of threatening phenomena, or hazards, and a susceptible population. Beyond, the theme of emerging infectious diseases and its links with global environmental and societal changes leads to reconsider some well-established knowledge in infectiology and parasitology.

Distribution Characteristics of Spermophilus dauricus in Manchuria City in China in 2015 through '3S' Technology

Plague is a virulent infectious disease in China. In this study, '3S' technology was used to perform spatial autocorrelation analysis and spatial interpolation analysis for Spermophilus dauricus (S. Dauricus, a species of ground squirrel) captured in Manchuria City in 2015. The results were visually inspected. During the two-month (May to July) plague surveillance in 2015, 198 S. dauricus individuals were captured in the study area in Manchuria City (48 monitoring areas) by using a day-by-day catching method. Spatial autocorrelation was conducted using the ArcGIS software, and the following significantly different results were obtained: Moran's I=0.228472, Z-score=2.889126, and P<0.05. Thus, a spatial aggregation was observed. In 2015, the distribution of S. dauricus diminished from west to east and from north to south of Manchuria. Geo Detector software was used to analyze the habitat factors affecting the spatial distribution of S. dauricus. This highly clustered species mainly exists in suburban communities, construction sites, and areas surrounding factories. In future studies, plague surveillances should be performed in areas around Manchuria and Zhalainuoer.

[Molecular epidemiology of phlebovirus in four provinces in Morocco]

Sandflies are vectors of protozoa, viruses, and bacteria. To investigate the transmission of phleboviruses, a total of 8753 sandflies were collected in four foci of leishmania. A total of 16 distinct species were morphologically identified. Nested-PCR and cell culture screening for phleboviruses, using an assay targeting the polymerase gene, showed positive results for 19 pools of sandflies. Sequencing of the corresponding products confirmed the results and allowed identification of Toscana virus exclusively. Corresponding sandfly species originated from four different foci, and were different from those commonly reported in the literature. Sequence analysis shows that the Moroccan Toscana viruses belong to genotype B and appear close to the Toscana viruses isolated in France and Spain. This study reported the existence of the virus in the north, center and south of the country. The abundance and diversity of sandflies in Morocco, Mediterranean climate, would support the continuous circulation of Toscana virus in our country, posing a potential risk of emergence of these arboviruses.

Human-Bat Interactions in Rural West Africa

Because some bats host viruses with zoonotic potential, we investigated human-bat interactions in rural Ghana during 2011-2012. Nearly half (46.6%) of respondents regularly visited bat caves; 37.4% had been bitten, scratched, or exposed to bat urine; and 45.6% ate bat meat. Human-bat interactions in rural Ghana are frequent and diverse.

Phylogeography of Influenza A(H3N2) Virus in Peru, 2010-2012

It remains unclear whether lineages of influenza A(H3N2) virus can persist in the tropics and seed temperate areas. We used viral gene sequence data sampled from Peru to test this source-sink model for a Latin American country. Viruses were obtained during 2010-2012 from influenza surveillance cohorts in Cusco, Tumbes, Puerto Maldonado, and Lima. Specimens positive for influenza A(H3N2) virus were randomly selected and underwent hemagglutinin sequencing and phylogeographic analyses. Analysis of 389 hemagglutinin sequences from Peru and 2,192 global sequences demonstrated interseasonal extinction of Peruvian lineages. Extensive mixing occurred with global clades, but some spatial structure was observed at all sites; this structure was weakest in Lima and Puerto Maldonado, indicating that these locations may experience greater viral traffic. The broad diversity and co-circulation of many simultaneous lineages of H3N2 virus in Peru suggests that this country should not be overlooked as a potential source for novel pandemic strains.

[Scientific substantiation of sizes of sanitary protection zones of anthrax burial sites based on the comprehensive evaluation of risk factors]

In the Russian Federation anthrax epizootics are still being registered among animals as well as epidemic foci of the population. This situation is linked to natural reservoirs of the pathogen - numerous anthrax burial sites which belong to class I of dangerous objects. In this connection, a one-kilometer sanitary protective zone is required according to current Russian Federation legislation. As a result, a significant land of the country is unsuitable for any agricultural use. Meanwhile, epizootologo-epidemiological observations indicate to that different anthrax burial sites differ in their characteristics and represent varying degrees of the risk. In connection with the development of the agricultural sector, intensive construction and the development of new and abandoned areas there is a need of creating unified approaches to assess the risk of anthrax burial sites, as well as to determine the size of sanitary protection zones based on the risk assessment. This article represents an original methodology to assess the actual danger of anthrax burial sites. It is based on a comprehensive multi-factor quantity-related risk assessment, described by a model that accounting the importance of each study for natural, social and biological factors. Undertaking this methodology allowed to reveal a degree of danger of anthrax burial sites located in different territories of the Russian Federation, and helped to substantiate the dimensions of their sanitary protection zones.

[Further study on possibility of diffusion of Oncomelania hupensis with water in river channels of the east route of South-to-North Water Diversion Project]

OBJECTIVE

To study the drifting law of floats and potential risks of Oncomelania hupensis diffusion in the water diversion rivers of the east route of South-to-North Water Diversion Project.

METHODS

The O. hupensis snails in the river channels were monitored by the salvage method and snail luring method with rice straw curtains, and the diffusion possibility of snails along with water was assessed through the drift test of floats with GPS.

RESULTS

In the flood seasons from 2006 to 2013, totally 8 338.0 kg of floats were salvaged, and 2 100 rice straw curtains were put into water in the Li Canal and Jinbao shipping channel, but no Oncomelania snails were found. The drift test of floats with GPS before water diversion showed that the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.56 - 0.60 m/s, and the average drift distances each time were 999.70 - 1 995.50 m in the Gaoshui River section, while there were no obvious drift in Jinbao shipping channel section. During the water diversion period, the flow velocity on water surface (northbound) was 0.45 m/s, the average drift velocity of the floats was 0.35 - 0.41m/s, and the average drift distances each time were 1 248.06 -1 289.44 m in the Gaoshui River, while in Jinbao shipping channel section, the flow velocity on water surface was 0.28 m/s, the average drift velocity of the floats was 0.25 - 0.27 m/s, and the average drift distances each time were 477.76 - 496.38 m. The drift test showed that the floats gradually closed to the river bank as affected by water flow, wind direction and ship waves, when blocked by the reeds, water plants or other obstacles, and they would stopped and could not continue to drift without outside help.

CONCLUSIONS

There are no Oncomelania snails found in the river channels of the east route of South-to-North Water Diversion Project. The drifting distance of the floating debris along with the water is restricted by the flow rate and shore environment.

[Not Available]

Important preventive measures carried out in the herds of domestic animals have found improving the health status of farms, particularly for contagious diseases subject to mandatory declaration and accompanying drastic but necessary eradication measures in infected flocks. However it is more difficult to apply these same biosecurity measures on wildlife that may have been contaminated or not by domestic animals. The growing number of emerging infectious diseases of wildlife may reflect increased vigilance, but most often the result of a change in the ecology of the host, the causative agent or both. So, wildlife may be reservoirs of pathogens that can infect domestic herds again but mostly for the majority of them contaminating humans. This is the case, for example, of West Nile virus (WNV), avian influenza virus, rabies virus, Nipah virus, diseases transmitted by ticks, tuberculosis, brucellosis, hepatitis E or some parasitic zoonoses.

Squirrelpox virus: assessing prevalence, transmission and environmental degradation

Red squirrels (Sciurus vulgaris) declined in Great Britain and Ireland during the last century, due to habitat loss and the introduction of grey squirrels (Sciurus carolinensis), which competitively exclude the red squirrel and act as a reservoir for squirrelpox virus (SQPV). The disease is generally fatal to red squirrels and their ecological replacement by grey squirrels is up to 25 times faster where the virus is present. We aimed to determine: (1) the seropositivity and prevalence of SQPV DNA in the invasive and native species at a regional scale; (2) possible SQPV transmission routes; and, (3) virus degradation rates under differing environmental conditions. Grey (n = 208) and red (n = 40) squirrel blood and tissues were sampled. Enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qPCR) techniques established seropositivity and viral DNA presence, respectively. Overall 8% of squirrels sampled (both species combined) had evidence of SQPV DNA in their tissues and 22% were in possession of antibodies. SQPV prevalence in sampled red squirrels was 2.5%. Viral loads were typically low in grey squirrels by comparison to red squirrels. There was a trend for a greater number of positive samples in spring and summer than in winter. Possible transmission routes were identified through the presence of viral DNA in faeces (red squirrels only), urine and ectoparasites (both species). Virus degradation analyses suggested that, after 30 days of exposure to six combinations of environments, there were more intact virus particles in scabs kept in warm (25°C) and dry conditions than in cooler (5 and 15°C) or wet conditions. We conclude that SQPV is present at low prevalence in invasive grey squirrel populations with a lower prevalence in native red squirrels. Virus transmission could occur through urine especially during warm dry summer conditions but, more notably, via ectoparasites, which are shared by both species.

An increasing danger of zoonotic orthopoxvirus infections

On May 8, 1980, the World Health Assembly at its 33^rd session solemnly declared that the world and all its peoples had won freedom from smallpox and recommended ceasing the vaccination of the population against smallpox. Currently, a larger part of the world population has no immunity not only against smallpox but also against other zoonotic orthopoxvirus infections. Recently, recorded outbreaks of orthopoxvirus diseases not only of domestic animals but also of humans have become more frequent. All this indicates a new situation in the ecology and evolution of zoonotic orthopoxviruses. Analysis of state-of-the-art data on the phylogenetic relationships, ecology, and host range of orthopoxviruses—etiological agents of smallpox (variola virus, VARV), monkeypox (MPXV), cowpox (CPXV), vaccinia (VACV), and camelpox (CMLV)—as well as the patterns of their evolution suggests that a VARV-like virus could emerge in the course of natural evolution of modern zoonotic orthopoxviruses. Thus, there is an insistent need for organization of the international control over the outbreaks of zoonotic orthopoxvirus infections in various countries to provide a rapid response and prevent them from developing into epidemics.

[Visceral leishmaniasis in Argentina. Cases notification and distribution of vectors (2006-2012)]

Visceral leishmaniasis (VL) is a notifiable disease in Argentina. Every new case diagnosed must be reported to the National Health Surveillance System. In the period 2006-2012, a total of 103 cases have been notified in four provinces: Entre Rios, Santa Fe, Misiones and Santiago del Estero. Misiones has the largest amount of cases: a total of 80, detected in 15 towns from May 2006 to July 2012. The highest incidence is observed in children (less than 15 years of age). In 2004 the vector Lutzomyia longipalpis was detected for the first time in Formosa Province. Cases of human and canine VL, as well as the presence of the canine vector were reported in 2006 in the province of Misiones, and in 2008-2009 in the province of Corrientes. In Santiago del Estero cases of human and canine VL (2008) were possibly associated with secondary vectors. In 2010 Lu longipalpis was found in Entre Rios, showing its dispersal to the south. Between January and April 2011 a systematic search of the VL vector was carried out in 13 towns, in Entre Ríos, Santa Fe and Santiago del Estero Provinces (275 traps/night). The colonization of the vector Lu longipalpis was proved in Chajarí town (Entre Rios), but not in Santiago del Estero Province, where Migonemyia migonei appears as a putative LV vector.

Polymerase chain reaction (PCR) investigations of prepatent Schistosoma haematobium cercariae incidence in five water bodies, South West, Nigeria

This study investigated the levels of prepatent S. haematobium infection in water samples collected from Schistosomiasis haematobium transmission namely: International Institute of Tropical Agriculture (IITA) river and Eleyele river in Oyo state, Oyan dam and Shokori river in Ogun state, Badagry Lagoon and Lagoon (University of Lagos, Lagos state).

METHODOLOGY

Polymerase chain reaction (PCR) assay amplifying the Dra I repeated sequence of S. haematobium cercariae from the water samples was used. Samples of cercariae obtained from a laboratory population of Bulinus globosus and Bulinus rohlfsi snails were assayed following DNA extraction as control. Physico-chemical parameters of the water bodies were determined.

RESULTS

Physico-chemical parameters showed that salinity, conductivity and total dissolved solids were relatively high in the Lagoon front samples (41.91 ppt, 62400.87 micros/cm, 31000.14 mg/L and 7.79), and low in the river samples (13.27 ppt, 1325.67 micros/cm, 11470 mg/L and 8.36 respectively) while pH were similar. PCR showed that 3 out of the 6 water bodies sampled namely IITA river, Eleyele river and Oyan Dam are S. haematobium endemic sites as they gave positive signals.

CONCLUSION

Three surveyed sites with relatively low salinity namely IITA river, Eleyele river and Oyan dam are high S. haematobium endemic areas and schistosomes survive perhaps best in low salinity environment. PCR could be a more valuable tool in the study of incidence and prevalence of S. haematobium infection compared with conventional cercariae shedding method. On the known strength of focal effects of environmental conditions, implications of these results in the epidemiology and design of control activities are encouraging.

Modelling zoonotic diseases in humans: comparison of methods for hantavirus in Sweden

Because their distribution usually depends on the presence of more than one species, modelling zoonotic diseases in humans differs from modelling individual species distribution even though the data are similar in nature. Three approaches can be used to model spatial distributions recorded by points: based on presence/absence, presence/available or presence data. Here, we compared one or two of several existing methods for each of these approaches. Human cases of hantavirus infection reported by place of infection between 1991 and 1998 in Sweden were used as a case study. Puumala virus (PUUV), the most common hantavirus in Europe, circulates among bank voles (Myodes glareolus). In northern Sweden, it causes nephropathia epidemica (NE) in humans, a mild form of hemorrhagic fever with renal syndrome.Logistic binomial regression and boosted regression trees were used to model presence and absence data. Presence and available sites (where the disease may occur) were modelled using cross-validated logistic regression. Finally, the ecological niche model MaxEnt, based on presence-only data, was used.In our study, logistic regression had the best predictive power, followed by boosted regression trees, MaxEnt and cross-validated logistic regression. It is also the most statistically reliable but requires absence data. The cross-validated method partly avoids the issue of absence data but requires fastidious calculations. MaxEnt accounts for non-linear responses but the estimators can be complex. The advantages and disadvantages of each method are reviewed.

Diversity of containers and buildings infested with Aedes aegypti in Puerto Iguazú, Argentina

Aedes aegypti is the main domestic vector of the dengue virus. Control measures to prevent dengue transmission focus on the treatment and elimination of this vector's oviposition sites. There is limited biological information on Ae. aegypti in Argentina. The aim of this study was to characterize Ae. aegypti oviposition sites in the city of Puerto Iguazú, Argentina. We surveyed an area covering nine neighborhoods in 2005. We identified 191 premises as positive for Ae. aegypti, giving a general house index of 9.6%. Premises classified as residential and vacant lots presented the highest number of infested premises, with 9% and 22% respectively. The total number of surveyed containers was 29,600. The overall container index (CI) was 1.1. The most frequently infested containers were water tanks (CI = 37). These preliminary results suggest that vacant lots and water tanks provide suitable breeding areas and environmental conditions, improving the chances of Ae. aegypti survival in Puerto Iguazú.

Identification of Chinese plague foci from long-term epidemiological data

Carrying out statistical analysis over an extensive dataset of human plague reports in Chinese villages from 1772 to 1964, we identified plague endemic territories in China (i.e., plague foci). Analyses rely on (i) a clustering method that groups time series based on their time-frequency resemblances and (ii) an ecological niche model that helps identify plague suitable territories characterized by value ranges for a set of predefined environmental variables. Results from both statistical tools indicate the existence of two disconnected plague territories corresponding to Northern and Southern China. Altogether, at least four well defined independent foci are identified. Their contours compare favorably with field observations. Potential and limitations of inferring plague foci and dynamics using epidemiological data is discussed.

[Outbreak of acute enterovirus intestinal infection in Sakhalin region in August 2010]

The investigation of cases of acute intestinal infections in the Sakhalin region of Russia in August, 2010 is described. Epidemiological and molecular biological studies were conducted. After initial PCR screening and determining the nucleotide sequences of the positive samples the following enteroviruses were found: Coxsackie A2 - 42 samples (45%), Coxsackie A4--31 sample (34%), Enterovirus 71--6 samples (6,5%), Coxsackievirus B5--6 samples (6,5%), Coxsackie B3--4 samples (4%) and Coxsackie B1--4 samples (4%). The phylogenetic analysis of sequences showed that the closest analogues for the nucleotide sequences of these genotypes were previously identified in Japan, Korea and China in 2000-2010.

[Eco-geographic landscapes of natural plague foci in China I. Eco-geographic landscapes of natural plague foci]

OBJECTIVE

To study the eco-geographic landscapes of natural plague foci, in China.

METHODS

According to the surveillance records on plague epidemics and the eco-geographic landscapes of natural plague foci based on the county level, the criterion for classifying the ecological geographic zone of Chinese natural plague foci was established.

RESULTS

12 types and 19 subtypes of eco-geographic landscapes on Chinese natural plague foci were identified.

CONCLUSION

Scientific basis for Chinese natural plague foci classification was provided.

Research options for controlling zoonotic disease in India, 2010-2015

Background

Zoonotic infections pose a significant public health challenge for low- and middle-income countries and have traditionally been a neglected area of research. The Roadmap to Combat Zoonoses in India (RCZI) initiative conducted an exercise to systematically identify and prioritize research options needed to control zoonoses in India.

Methods and Findings

Priority setting methods developed by the Child Health and Nutrition Research Initiative were adapted for the diversity of sectors, disciplines, diseases and populations relevant for zoonoses in India. A multidisciplinary group of experts identified priority zoonotic diseases and knowledge gaps and proposed research options to address key knowledge gaps within the next five years. Each option was scored using predefined criteria by another group of experts. The scores were weighted using relative ranks among the criteria based upon the feedback of a larger reference group. We categorized each research option by type of research, disease targeted, factorials, and level of collaboration required. We analysed the research options by tabulating them along these categories. Seventeen experts generated four universal research themes and 103 specific research options, the majority of which required a high to medium level of collaboration across sectors. Research options designated as pertaining to ‘social, political and economic’ factorials predominated and scored higher than options focussing on ecological, genetic and biological, or environmental factors. Research options related to ‘health policy and systems’ scored highest while those related to ‘research for development of new interventions’ scored the lowest.

Conclusions

We methodically identified research themes and specific research options incorporating perspectives of a diverse group of stakeholders. These outputs reflect the diverse nature of challenges posed by zoonoses and should be acceptable across diseases, disciplines, and sectors. The identified research options capture the need for ‘actionable research’ for advancing the prevention and control of zoonoses in India.

Identifying residual foci of Plasmodium falciparum infections for malaria elimination: the urban context of Khartoum, Sudan

Background

Identifying the location and size of residual foci of infections is critical where malaria elimination is the primary goal. Here the spatial heterogeneity of Plasmodium falciparum infections within the urban extent of Khartoum state in Sudan is investigated using data from cross-sectional surveys undertaken from 1999 to 2008 to inform the Khartoum Malaria Free Initiative (KMFI).

Methods

From 1999–2008 the KMFI undertook cross-sectional surveys of 256 clusters across 203 random samples of residential blocks in the urban Khartoum state in September of each year. Within sampled blocks, at least five persons, including at least one child under the age of five years, were selected from each household. Blood smears were collected from the sampled individuals to examine the presence of P. falciparum parasites. Residential blocks were mapped. Data were analysed for spatial clustering using the Bernoulli model and the significance of clusters were tested using the Kulldorff scan statistic.

Results

A total of 128,510 malaria slide examinations were undertaken during the study period. In 1999, overall prevalence was 2.5%, rising to 3.2% in 2000 and consistently staying below 1% in subsequent years. From 2006, over 90% of all surveyed clusters reported no infections. Spatial clustering of infections was present in each year but not statistically significant in the years 2001, 2002, 2004 and 2008. Spatial clusters of high infection were often located at the junction of the Blue and White Niles.

Conclusion

Persisting foci of malaria infection in Khartoum are likely to distort wide area assessments and disproportionately affect future transmission within the city limits. Improved investments in surveillance that combines both passive and active case detection linked to a geographic information system and a more detailed analysis of the location and stability of foci should be undertaken to facilitate and track malaria elimination in the state of Khartoum.

[Distribution of Lutzomyia longipalpis in the Argentine Mesopotamia, 2010]

The first case of visceral leishmaniasis (VL) in Argentina was reported in 2006 in Posadas, Misiones. During the summer 2008-2009 Lutzomyia longipalpis, the VL vector, and canine VL cases were already spread along the province of Corrientes. In order to know the distribution of VL risk, systematic captures of the vector were performed between February and March 2010, in 18 areas of the provinces of Entre Ríos and Corrientes, and the city of Puerto Iguazú, Misiones, with a total of 313 traps/night. We confirmed the presence of Lu. longipalpis, for the first time in Chajarí (Entre Ríos), Alvear, La Cruz, Curuzú Cuatiá and Bella Vista (Corrientes), and Puerto Iguazú (Misiones). In Santo Tome and Monte Caseros (Corrientes), where the vector had been previously reported, traps with more samples were obtained with 830 and 126 Lu. Longipalpis trap/site/night respectively. These results show that the vector of urban VL continues spreading in the Argentine territory. Simultaneously, the spread of the parasite and the resulting human VL cases are associated with the dispersion of reservoirs, infected dogs, with or without clinical symptoms or signs, due to human transit.

[Potential risk factors for alveolar echinococcosis in humans in Poland]

The high prevalence of Echinococcus multilocularis recorded in foxes in Poland creates the risk of alveolar echinococcosis in humans. Sensational press releases on threats which had appeared during last few years do not favour the rational opinion on the risk of this dangerous disease. Based on accessible epidemiological data the potential risk factors of alveococcosis are addressed in this article.

[Bats and other reservoir hosts of Filoviridae. Danger of epidemic on the African continent?--a deductive literature analysis]

Ebola and Marburg virus, forming the Filoviridae family, cause hemorrhagic fever in countries of sub-Saharan Africa. These viral diseases are characterized by a sudden epidemic occurrence as well as a high lethality. Even though a reservoir host has not been approved yet, literature indicates the order of bats (Chiroptera) as a potential reservoir host. Significant references lead to a delineation of a hypothetical ecosystem of Filoviridae including Chiroptera. IgG-specific Ebola-Zaire antibodies were detected in Hammer-headed Bats (Hypsignathus monstrosus), Epauletted Fruit Bats (Epomops franqueti), and Little Collared Fruit Bats (Myonycteris torquata) during Ebola outbreaks between 2001 and 2005 in Gabon and the Republic of the Congo. The discovery of IgG-specific-Marburg virus antibodies and virus-specific ribonucleic acid in Egyptian Fruit Bats (Rousettus aegyptiacus) provided further indication for the exploration of the reservoir host. In 2007, the Marburg virus isolation could for the first time be accomplished directly from apparently healthy and naturally infected Egyptian Fruit Bats (Rousettus aegyptiacus) in Kitaka Mine (Uganda). Risk groups can be defined through chronological reprocessing and interpretation of existing epidemic-outbreaks on the African continent and the search for infection reasons of the index cases. The following risk factors for an infection with Ebola or Marburg virus must be put into consideration: Contact with and consumption of wild animal carcasses, sightseeing in caves as well as work in mines. The focus of this review is the demonstration of risk profiles and their exposure to Chiroptera and other potential reservoir hosts.

Andes virus infections in the rodent reservoir and in humans vary across contrasting landscapes in Chile

Hantavirus cardiopulmonary syndrome (HCPS) is an emerging infectious disease first reported in Chile in 1995. Andes hantavirus (ANDV) is responsible for the more than 500 cases of HCPS reported in Chile. Previous work showed that ANDV is genetically differentiated in Chile across contrasting landscapes. To determine whether the reservoir rodent (Oligoryzomys longicaudatus) populations are also geographically segregated, we conducted range-wide spatial genetic analyses of O. longicaudatus in Chile using the mitochondrial DNA cytochrome b gene. Given that landscape structure influences the incidence of hantavirus infections, we also tested 772 O. longicaudatus specimens for antibodies to ANDV captured during the period 2000-2006. Population genetic analyses of O. longicaudatus are largely congruent with those reported for ANDV, with the host primarily differentiated according to three defined ecoregions, Mediterranean, Valdivian rain forest and North Patagonian rain forest. Significant differences in the relative prevalence of anti-ANDV antibodies in rodent samples also were found across the three ecoregions. We relate these results to the number of reported human HCPS cases in Chile, and discuss the importance of landscape differences in light of ANDV transmission to humans and among rodent populations.

Q fever in the Netherlands: an update on the epidemiology and control measures

Since the steady rise in human cases which started in 2007, Q fever has become a major public health problem in the Netherlands with 2,357 human cases notified in the year 2009. Ongoing research confirms that abortion waves on dairy goat farms are the primary source of infection for humans, primarily affecting people living close (under 5 km) to such a dairy goat farm. To reverse the trend of the last three years, drastic measures have been implemented, including the large-scale culling of pregnant goats on infected farms.

[Cryptosporidium spp. and Giardia spp.--environmental studies in Poland]

Cryptosporidium spp. and Giardia spp. are intestinal protozoan parasites of humans and many other species of mammals. The aim of this article was to summarize the last twenty years of research on the environmental distribution of these parasites, with a particular emphasis on the natural reservoir of invasion and human infections in Poland. The prevalence of Cryptosporidium and Giardia has been studied in different groups of humans, in wildlife, pets and farm animals and in environmental samples. Current knowledge on the distribution of zoonotic and non-zoonotic species/genotypes in reservoir hosts and environmental samples has been summarized. The usefulness of different methods for the detection and identification of the parasites in different types of samples has been presented. Due to the wide distribution and high prevalence of both species in a range of hosts and possible vectors involved in mechanical transmission, the overall risk of outbreaks of cryptosporidiosis and giardiosis in Poland has been assessed as relatively high.

[Distribution of vectors of visceral leishmaniasis in the Province of Corrientes, 2008]

Visceral leishmaniasis (VL) is a relevant parasitic disease in public health, produced by Leishmania infantum chagasi. Since the urbanization and emergence in Southern Brazil and Paraguay, the vector Lutzomyia longipalpis in Formosa, 2004, and the first human visceral leishmaniasis case in Misiones, 2006, have been reported in Argentina. Due to the reports of canine VL, a search of the vector in the Province of Corrientes, contiguous to Misiones, was performed during December 2008. Standarized trapping detected 376 Lu. longipalpis in Ituzaingó, Virasoro, Santo Tomé, Garruchos, Riachuelo, Corrientes and Monte Caseros localities. The risk of autochtonous vectorial transmission was then confirmed in the Province of Corrientes. The distribution of vectors in populated urban areas, with intense transit of canine reservoirs from localities with high transmission, and the existence of infected reservoirs, also implies epidemic risk.

Class 1 integrons and multidrug resistance among Escherichia coli isolates from human stools

Three hundred and eighteen Escherichia coli isolates from stools of healthy volunteers and outpatients from a major university hospital in southern Thailand were tested for the presence of class 1 integrons using multiplex-PCR and for their susceptibility against 12 antimicrobial agents using standard disc diffusion method. Based on the presence of intl1, 162 isolates harbored class 1 integrons, which were more prevalent in isolates from outpatients compared with those from healthy volunteers. The majority (85%) of the isolates were resistant to at least one antimicrobial agent with the following percent resistance: streptomycin 66%, tetracycline 60%, sulphamethoxazole 59%, ampicillin 52%, trimethoprim/sulphamethoxazole 47%, kanamycin 30%, nalidixic acid 27%, ciprofloxacin 23%, norfloxacin 22%, amoxicillin/ clavulanic acid 16%, gentamicin 8%, and amikacin 2%. The most frequent pattern of multiresistant strains (11%) was sulphamethoxazole- trimethoprim/sulphamethoxazole -ampicillin-tetracycline-streptomycin. Multiple drug resistance was more frequent in integron-positive isolates (89%) than those in integron-negative E. coli (57%). These data indicate that human fecal E. coli is a reservoir of antibiotic-resistant genes that poses a significant risk of the spread of microbial resistance in the community.

Dogs L. infantum infection from an endemic region of the north of Tunisia: a prospective study

A follow-up study of 917 dogs was undertaken between 1994 and 1995 in the focus of visceral leishmaniasis in northern Tunisia. It permitted to assess the demography of the dog population, the importance of canine leishmaniasis (CL) and the determinants of seropositivity and mortality of dogs. Canine population was stable through time with an input of 231 dogs and an output of 218 dogs per year. The prevalence of seropositivity was 18% and 22.3% in 1994 and 1995 respectively and 90% of dogs were asymptomatic. Among 525 negative dogs in 1994 and reassessed in 1995, 78 seroconverted revealing an annual cumulative incidence of 14.74%. On the other hand, 23.47% (27/115) of seropositive dogs became negative in 1995. Age, presence of symptoms and density of dogs were independently associated with CL seropositivity. These results demonstrate the difficulty of control strategies of visceral leishmaniasis targeting the dog population.

Vectors and reservoirs of cutaneous leishmaniasis in Marvdasht district, southern Islamic Republic of Iran

An epidemiological study was made of vectors and reservoirs of cutaneous leishmaniasis in rural regions of Marvdasht, Fars province, southern Islamic Republic of Iran during 2003-04. Using live traps, 126 rodents were collected: 75.4% were Meriones libycus, 14.3% Cricetulus migratorius and 10.3% Microtus arvalis. Eight out of 95 Meriones libycus (8.4%) were found to be infected with Leishmania major, identified by nested-PCR; none of the other rodents were positive. Female sandflies were collected from indoor locations: 75% were Phlebotomus papatasi and only 2.7% were found naturally infected with L. major. This is the first report of P. papatasi as a proven vector of zoonotic cutaneous leishmaniasis in this area.

[Dispersal of the flea Ctenophyllus hirticrus and spreading of plague epizooties in Gorny Altai]

Gradual dispersion of an abundant flea species Ctenophyllus hirticrus specific to the Pallas's pika (the main plague carrier), is revealed in the Gorno-Altai natural plague focus on the territory, occupied by two populations of this lagomorph. Spreading of Yersinia pestis in these areas took place a short time later the rise of this ectoparasite's abundance. It is supposed that the colonization of these areas by C. hirticrus was one of the factors determined epizooties spreading within the focus and formation of new sites of stable Y. pestis preservation.

[Seasonal variation of Aedes aegypti and Aedes albopictus in a city of Southeastern Brazil]

OBJECTIVE

To assess the seasonal variation of Aedes aegypti and Aedes albopictus and to estimate the association between the species abundance and abiotic factors.

METHODS

Tire-traps were kept for a period of 15 days monthly in an urban area of the city of Potim in the state of São Paulo, Southeastern Brazil, from November 2002 to October 2003. Samples of immature forms were followed up under laboratory conditions for 29 days and species were identified. The association between abundance and temperature, rainfall and air relative humidity was tested using Spearman correlations (r s). The descriptive statistics were presented by the average and the standard error (alpha=0.05).

RESULTS

From a total of 20,727 immatures collected, 95.3% were Ae. aegypti and 4.7%, Ae. albopictus. Ae. aegypti was found throughout the whole year while Ae. albopictus was found from November to July. The association between these species and abiotic factors was significant for Ae. aegypti (p=0.04) as for maximum temperature and for Ae. albopictus as for maximum temperature (p=0.01) and rainfall (p=0.02).

CONCLUSIONS

Both species presented seasonal variation. However, Ae. aegypti was found throughout the whole year showing a decrease between April and May and June and July. Ae. albopictus, less abundant, was found only between November, 2002 and July, 2003 with a peak in April, 2003. The higher abundance of Ae. aegypti compared to Ae. albopictus in an urban area showed Ae. aegypti has greater capacity of colonizing tires. Such a breeding site in the environment may be important to the maintenance and abundance of Ae. aegypti.

Sero-epidemological survey on canine visceral leishmaniasis and the distribution of sandfly vectors in northwestern Turkey: prevention strategies for childhood visceral leishmaniasis

Visceral leishmaniasis (VL) caused by Leishmania infantum, is an endemic disease in Aegean and Mediterranean Regions among humans and dogs. In this study, a sero-epidemiological survey for VL and cutaneous leishmaniasis (CL), which both are sporadically reported in the region, were carried out in the villages of Eskisehir, Afyon, and Bilecik cities. The study was designed according to the location of the sporadic cases of VL and CL, and blood samples of 111 dogs were randomly collected. Lymph node aspiration samples were taken from dogs that have popliteal lymphadenopathy. Sand flies were also collected using CDC light traps in the several localities. The sera samples were screened using IFAT, ELISA, rk39 ELISA and dip-stick tests for anti-Leishmania antibodies. A total of 15 (13.51 per cent) dogs out of 111 were found to be seropositive by at least one of the tests. The seropositivity ratios among dogs were found to be 27.5 per cent (8/29), 9.09 per cent (4/44) and 7.8 per cent (3/38) in Afyon, Bilecik and Eskisehir cities respectively. Leishmania amastigotes were detected in 4 of the 14 lymph node aspiration samples (eight seronegative, six seropositive), and all of them were seropositive dogs. One year later, two of the dogs were found to be dead and the other two were severely ill. Among the 179 collected Phlebotomus specimens from, Phlebotomus major was found to be abundant (35.7 per cent) and the other species were P. simici (28.5 per cent), P. similis (34.7 per cent) and P. alexandri (1.1 per cent). In the study area, canine VL is more spread than human VL. Because dogs are playing an important role for VL in Mediterranean Basin, and development of appropriate control measures will be necessary for childhood VL.

Meriones libycus is the main reservoir of zoonotic cutaneous leishmaniasis in south Islamic Republic of Iran

A study was made in rural regions around Neiriz city, Fars province in the south of the Islamic Republic of Iran during 2002-03 to further investigate a new focus of zoonotic cutaneous leishmaniasis. Meriones libycus was the dominant rodent (100% of 65 rodents collected) and 4.6% were naturally infected with the amastigote form of Leishmania spp. Promasigotes were identified as L. major. This confirms M. libycus as the main reservoir host of zoonotic cutaneous leishmaniasis in southern parts of the country.