Plague Transmission Research Articles

Impact of Sanitation on Rodent Pullulation and Plague Status in an Informal Settlement on the Outskirts of Mahajanga (Madagascar)

Plague is a zoonotic disease caused by Yersinia pestis, and it is endemic in Madagascar. The plague cycle involves wild and commensal rodents and their fleas; humans are an accidental host. Madagascar is the country where plague burden is the highest. Plague re-emerged in Mahajanga, the western coast of Madagascar, in the 1990s and infected populations in the popular and insalubrious zones. Sanitation is considered a primary barrier to infection by excluding pathogens from the environment and reservoirs. Poor housing and hygiene and proximity to rodents and fleas in everyday life are major and unchanged risk factors of plague. The aim of this study was to measure the impact of sanitation on Yersinia pestis bacteria in human and small mammal reservoirs and flea vectors. This study was conducted on 282 households within 14 neighborhoods. Two sessions of sampling were conducted in 2013 and 2016. Small mammals were trapped inside and around houses using live traps. Fleas, blood and spleen were sampled to detect Y. pestis infection and antibodies and determine the level of plague circulation before and after the installation of sanitation in order to assess the impact of sanitation improvement on inhabitant health. Two major types of housing can be described, i.e., formal and informal (traditional), scattered in all the suburbs. Among the small mammals captured, 48.5% were Suncus murinus, and 70% of houses were infested. After sanitation, only 30% of houses remained infested, and most of them were located around the market. Fleas were mostly Xenopsylla cheopis. Before and after intervention, the overall prevalence of fleas was the same (index 4.5) across the 14 suburbs. However, the number of houses with fleas drastically decreased, and the flea index increased significantly in rodent-infested houses. Rodent abundance also decreased from 17.4% to 6.1% before and after intervention, respectively. A serology study highlights that plague is still circulating in Mahajanga, suggesting that small mammals maintain enzootic plague transmission in the city.

Impacts of ectoparasite flea infestation on gut microbiota of the Meriones unguiculatus in a rodent-flea system.

Fleas, along with one of their host species, Meriones unguiculatus, possess the capability to act as vectors in the transmission of plague. Parasitism by fleas may markedly influence the physiology and immune system of their hosts. Gut microbiota plays an important role in the growth and development of rodents. However, few studies have explored the impacts of ectoparasitic flea on the gut microbiome of rodents. This study investigated the immunological responses and changes in the gut microbial diversity and composition in both wild and laboratory rodents infested with fleas and laboratory rodents infested with Ctenocephalides felis. We measured immune reactions post-infestation by enzyme-linked immunosorbent assay (ELISA) and explored the effects of ectoparasitic infestation on the diversity and composition of the rodent gut microbiota in microbiome studies by 16S rRNA gene sequencing techniques. After flea infestation, results from 16S rRNA gene sequencing techniques indicated a significant increase in alpha diversity, affecting the composition of the gut microbiota. At the genus level, the abundance of the harmful bacterium Desulfovibrio increased. Beta diversity analyses showed significant differences between the gut microbiota of the experimental and control groups. ELISA results revealed significantly elevated levels of IgG in parasitized mice, while the differences in IgA levels were not significant. Flea infections affect the composition and diversity of the gut microbiota in the M. unguiculatu, and it has been found that the biomarker Desulfovibrio increases following flea infection in these rodents. Our results indicate that the gut microbiota can regulate the stability of the rodent-flea system. These findings may provide a foundation for exploring preventive measures against plague and aid in developing more effective treatments for the infection.

An overview of the first human case of Bubonic plague detected in Bugat settlement, Gobi-Altai province in Mongolia

On June 27th, 2023, Mongolia registered its first case of bubonic plague in the Bugat settlement, Gobi-Altai province. Cases in this outbreak are widespread throughout the country with multiple close contacts identified and monitored. Environmental surveillance, including the testing of marmots, picked up the presence of Yersinia Pestis in many samples prior to the beginning of the outbreak. Marmots are seen as a delicacy in Mongolia which presents a challenge when preventing animal to human transmission of bubonic plague via the consumption of raw undercooked marmot meat. Although bubonic plague is endemic in Mongolia, cases are often sporadic and mostly registered in the western provinces of the region however, one case was recorded in the capital city of Ulan Bator on the eastern side of the country. The nature of this outbreak highlights the importance of effective preventive measures such as, PPE, awareness campaigns, health literacy and safe food handling practices.

Knowledge and practices related to plague persistence in plague-endemic foci, Mbulu District, Tanzania.

Plague continues to be a major public health concern in African countries. Several social practices and environmental conditions have been associated with the reoccurrence of bubonic plague, especially in places where the disease is prevalent. Therefore, it remains important to understand people knowledge, behavior and practices related to disease risks in order to identify factors that may hinder prevention and control strategies in the foci. A study survey of 100 households was conducted in Mbulu district to assess plague knowledge, factors that influence flea bite and measures used for rodent and flea control. Majority of participants (86%) were familiar with the plague disease and about (50%) mentioned swelling lymph nodes as a common symptom. Most of the participants (62%) claimed to observe human plague cases during the long rain season. The majority of participants (97%) reported to experience flea bite in their domestic settings, with most stating that they experienced more flea bites during the dry season. Houses with livestock had a greater likelihood of flea bite (OR = 2.7; 95% CI: 0.36-18.80, p = 0.267) compared to houses with no livestock. Furthermore, residents reported using both local and chemical methods to control rodents and flea inside houses. Most respondents preferred using local methods in flea control. Respondents stated that the efficacy of flea control methods being applied ranged from few days to several months. There was limited knowledge of the residual effects of the agricultural chemicals being used to control fleas among the surveyed community. Our study highlights the importance of raising awareness and adopting effective control methods for controlling fleas and lower the risk of plague transmission and other flea borne diseases in the local communities. Sensitization of the local community on the use of appropriate chemicals for flea control is urgent to avoid any potential long-term impacts of the residual effects on the health of the local communities.

Socio-ecological risk factors associated with human flea infestations of rural household in plague-endemic areas of Madagascar.

Plague is a flea-borne fatal disease caused by the bacterium Yersinia pestis, which persists in rural Madagascar. Although fleas parasitizing rats are considered the primary vectors of Y. pestis, the human flea, Pulex irritans, is abundant in human habitations in Madagascar, and has been found naturally infected by the plague bacterium during outbreaks. While P. irritans may therefore play a role in plague transmission if present in plague endemic areas, the factors associated with infestation and human exposure within such regions are little explored. To determine the socio-ecological risk factors associated with P. irritans infestation in rural households in plague-endemic areas of Madagascar, we used a mixed-methods approach, integrating results from P. irritans sampling, a household survey instrument, and an observational checklist. Using previously published vectorial capacity data, the minimal P. irritans index required for interhuman bubonic plague transmission was modeled to determine whether household infestations were enough to pose a plague transmission risk. Socio-ecological risk factors associated with a high P. irritans index were then identified for enrolled households using generalized linear models. Household flea abundance was also modeled using the same set of predictors. A high P. irritans index occurred in approximately one third of households and was primarily associated with having a traditional dirt floor covered with a plant fiber mat. Interventions targeting home improvement and livestock housing management may alleviate flea abundance and plague risk in rural villages experiencing high P. irritans infestation. As plague-control resources are limited in developing countries such as Madagascar, identifying the household parameters and human behaviors favoring flea abundance, such as those identified in this study, are key to developing preventive measures that can be implemented at the community level.

An epidemiological modeling investigation of the long-term changing dynamics of the plague epidemics in Hong Kong

<p>Identifying epidemic-driving factors through epidemiological modeling is a crucial public health strategy that has substantial policy implications for control and prevention initiatives. In this study, we employ dynamic modeling to investigate the transmission dynamics of pneumonic plague epidemics in Hong Kong from 1902 to 1904. Through the integration of human, flea, and rodent populations, we analyze the long-term changing trends and identify the epidemic-driving factors that influence pneumonic plague outbreaks. We examine the dynamics of the model and derive epidemic metrics, such as reproduction numbers, that are used to assess the effectiveness of intervention. By fitting our model to historical pneumonic plague data, we accurately capture the incidence curves observed during the epidemic periods, which reveals some crucial insights into the dynamics of pneumonic plague transmission by identifying the epidemic driving factors and quantities such as the lifespan of flea vectors, the rate of rodent spread, as well as demographic parameters. We emphasize that effective control measures must be prioritized for the elimination of fleas and rodent vectors to mitigate future plague outbreaks. These findings underscore the significance of proactive intervention strategies in managing infectious diseases and informing public health policies.</p>

Assessing the effectiveness of intervention to prevent plague through community and animal-based survey.

Bubonic plague, transmitted by infected flea bites, is the most common form of plague and, left untreated, can progress to the pneumonic form, which is highly contagious. Surveillance focusing on reservoir and vector is considered to be the main approach to prevent plague. Common rodent control methods include the use of rodenticide and snap traps but, in a plague context, the dispersal of fleas from killed animals may pose a serious health threat. Therefore, there is a need for strategies which address reservoir and vector control. The aim of this study was to assess the effects of combination of reservoir and vector control through community-based surveillance. Activities were implemented by local previously trained community agents in two active plague foci in Madagascar. Kartman bait stations containing rodenticide and insecticide were placed indoors while live traps were set outdoors. Small mammals were identified and killed with their fleas. Effectiveness of control measures was evaluated by comparison of plague incidence two years before and after intervention using data on reported human cases of plague from the Central Laboratory of Plague. A total of 4,302 small mammals were captured, with the predominance of the black rat Rattus rattus. Our results found a reduction in plague incidence in the treated site for at least two years after treatment. Community-based interventions played an important role in reducing contact between humans-rodents-fleas. Our study confirms the importance of animal surveillance during the low plague transmission season. The combination of reservoir and vector control with community involvement may be effective at reducing the risks of plague spillover to humans. The strategy of using Kartman bait stations indoors with live traps outdoors can be used to refine proactive plague prevention, however, due to the potential development of resistance to pesticides in flea and rat populations, overuse should be considered.

Engagement with Traditional Healers for Early Detection of Plague in Uganda.

In rural Uganda, many people who are ill consult traditional healers prior to visiting the formal healthcare system. Traditional healers provide supportive care for common illnesses, but their care may delay diagnosis and management of illnesses that can increase morbidity and mortality, hinder early detection of epidemic-prone diseases, and increase occupational risk to traditional healers. We conducted open-ended, semi-structured interviews with a convenience sample of 11 traditional healers in the plague-endemic West Nile region of northwestern Uganda to assess their knowledge, practices, and attitudes regarding plague and the local healthcare system. Most were generally knowledgeable about plague transmission and its clinical presentation and expressed willingness to refer patients to the formal healthcare system. We initiated a public health outreach program to further improve engagement between traditional healers and local health centers to foster trust in the formal healthcare system and improve early identification and referral of patients with plaguelike symptoms, which can reflect numerous other infectious and noninfectious conditions. During 2010-2019, 65 traditional healers were involved in the outreach program; 52 traditional healers referred 788 patients to area health centers. The diagnosis was available for 775 patients; malaria (37%) and respiratory tract infections (23%) were the most common diagnoses. One patient had confirmed bubonic plague. Outreach to improve communication and trust between traditional healers and local healthcare settings may result in improved early case detection and intervention not only for plague but also for other serious conditions.

Knockdown resistance mutations are common and widely distributed in Xenopsylla cheopis fleas that transmit plague in Madagascar.

Plague, caused by the bacterium Yersinia pestis, remains an important disease in Madagascar, where the oriental rat flea, Xenopsylla cheopis, is a primary vector. To control fleas, synthetic pyrethroids (SPs) have been used for >20 years, resulting in resistance in many X. cheopis populations. The most common mechanisms of SP resistance are target site mutations in the voltage-gated sodium channel (VGSC) gene. We obtained 25 collections of X. cheopis from 22 locations across Madagascar and performed phenotypic tests to determine resistance to deltamethrin, permethrin, and/or dichlorodiphenyltrichloroethane (DDT). Most populations were resistant to all these insecticides. We sequenced a 535 bp segment of the VGSC gene and identified two different mutations encoding distinct substitutions at amino acid position 1014, which is associated with knockdown resistance (kdr) to SPs in insects. Kdr mutation L1014F occurred in all 25 collections; a rarer mutation, L1014H, was found in 12 collections. There was a significant positive relationship between the frequency of kdr alleles and the proportion of individuals surviving exposure to deltamethrin. Phylogenetic comparisons of 12 VGSC alleles in Madagascar suggested resistant alleles arose from susceptible lineages at least three times. Because genotype can reasonably predict resistance phenotype, we developed a TaqMan PCR assay for the rapid detection of kdr resistance alleles. Our study provides new insights into VGSC mutations in Malagasy populations of X. cheopis and is the first to report a positive correlation between VGSC genotypes and SP resistance phenotypes in fleas. Widespread occurrence of these two SP resistance mutations in X. cheopis populations in Madagascar reduces the viability of these insecticides for flea control. However, the TaqMan assay described here facilitates rapid detection of kdr mutations to inform when use of these insecticides is still warranted to reduce transmission of plague.

Influence of biotic and abiotic factors on flea species population dynamics on Lasiopodomys brandtii.

Brandt's Vole (Lasiopodomys brandtii) is one of the most abundant rodent species in the grasslands of Inner Mongolia, China, and one of the main carriers of Yersinia pestis, the plague bacterium. There have been several instances of plague transmission among L. brandtii, and all of their dominant flea species are known carriers of plague. Little work has been done to understand the regulation of flea abundance on L. brandtii by biotic and abiotic factors. Here, we examine the impacts of host and climate variation on flea abundance on L. brandtii in May, July, and September of 2021 in the East Ujumqin Banner, Xilinhot City, Inner Mongolia Autonomous Region. We arrived at the following conclusions: 1) There were 8 flea species representing 2 families and 5 genera collected from L. brandtii, and Frontopsylla luculenta, Neopsylla pleskei orientalis, and Amphipsylla primaris mitis were most common. 2) Host body weight, host age, season, temperature, and humidity are key factors influencing flea abundance on L. brandtii. 3) Flea species vary in their respective responses to factors.

Digital Prompts and Narrative Cues: Storytelling in the 1450s and in the 2020s

The Cent Nouvelles nouvelles present challenges to student learners of French linguistically, culturally and in terms of the content of the stories. Investigations designed to interrogate how the stories might have been collected in the second half of the fifteenth century end up demonstrating how the storytelling environment shapes the stories that are told and the way that they are understood. The experience of storytelling online during a period of pandemic learning is very different from the same experience in a pre- or post-pandemic classroom. Methodologies, such as critical pedagogy and inquiry stance pedagogy, which had limited resonance in the pre-pandemic environment, became much more central to the learner’s experience in the online, pandemic environment. This confirms the practices of ‘Flux pedagogy’, as advocated by Sharon M. Ravitch. Similarly, reactions to a story featuring the transmission of plague can be shaped by a framing that includes or excludes direct reference to the risk of infection experienced by the listeners.

Associations between ecological diversity and rodent plague circulation in Yunnan Province, China, 1983-2020: A data-informed modelling study.

Following its resurgence in 1982, rodent plague has been linked to a wide range of circulation risks in Yunnan Province. The most serious public health concern associated with effective plague control is determining how various ecological variables influence the differential risk of transmission. We investigated the population dynamics of the hosts and vectors using large-scale epidemiological surveillance data. In a seasonal eco-epidemiological model, we evaluated the impact of ecological conditions on the vectored flea index (VFI) to determine the rate of plague transmission. The findings revealed a changing species composition in natural foci over time. Additionally, shifting distributional ranges of species by elevation may be vital in modulating the VFI. The model estimates indicate that the dynamic VFI contributes to spatiotemporal variance in transmission. The VFI could be a critical ecological indicator, allowing for real-time tracking and prompt intervention in the circulation of rodent plague. Understanding eco-epidemiological diversity can provide essential insights into effective responses to future plague resurgence.

A frameshift in Yersinia pestis rcsD alters canonical Rcs signalling to preserve flea-mammal plague transmission cycles.

Multiple genetic changes in the enteric pathogen Yersinia pseudotuberculosis have driven the emergence of Yesinia pestis, the arthropod-borne, etiological agent of plague. These include developing the capacity for biofilm-dependent blockage of the flea foregut to enable transmission by flea bite. Previously, we showed that pseudogenization of rcsA, encoding a component of the Rcs signalling pathway, is an important evolutionary step facilitating Y. pestis flea-borne transmission. Additionally, rcsD, another important gene in the Rcs system, harbours a frameshift mutation. Here, we demonstrated that this rcsD mutation resulted in production of a small protein composing the C-terminal RcsD histidine-phosphotransferase domain (designated RcsD-Hpt) and full-length RcsD. Genetic analysis revealed that the rcsD frameshift mutation followed the emergence of rcsA pseudogenization. It further altered the canonical Rcs phosphorylation signal cascade, fine-tuning biofilm production to be conducive with retention of the pgm locus in modern lineages of Y. pestis. Taken together, our findings suggest that a frameshift mutation in rcsD is an important evolutionary step that fine-tuned biofilm production to ensure perpetuation of flea-mammal plague transmission cycles.

Innovation and Adaptation

Innovation has been the cornerstone for advances in any field of endeavor throughout the history of man and has driven the relentless forward journey of the human race. This special Orthopedics issue highlights a number of articles that showcase innovations – ideas, devices, and systems.
 The article by Aljibe, et al. showcases a novel method of producing patient-specific templates. While it is still in its infancy, the in vitro model is a first step towards a goal of translating this technology into surgical applications. This is an example of innovation driving medicine forward. 3-D printing has evolved from a hobbyist’s dream to an important tool in prosthetics, industry, drug delivery, and medicine.1-3 It is certainly exciting that scientists, engineers, and medical practitioners in our country are beginning to engage in this trailblazing field.
 The article by Gavino, et al. combines two highly specialized procedures – brachial plexus reconstruction and markerless motion analysis, the latter an innovation in itself, and creates a novel method of evaluating results of surgical procedures.4,5 Treatment of brachial plexus injuries, which bring catastrophic damage to the nerve supply to the upper extremity, need accurate evaluation of their outcomes. Only by knowing what is achieved by current treatments can we hope to better the plight of these patients.
 Genuino, et al. present a paradigm shift in delivery of services in a tertiary hospital whose main client base are the indigent. An innovation in the provision of necessary orthopedic implants to patients who have no capacity to pay for these themselves allows the bypass of charitable donors and puts the responsibility of supplying and paying for these implants on the government. This is a small but vital cog in the journey towards universal health care.
 Adaptation is highlighted by the changes forced upon us by the COVID-19 pandemic. The treatment of fragility fractures, a fraught process in the best of times, was further complicated with the restrictions that came with the lockdown. Risks already present in this elderly population were compounded by risks of transmission of this modern plague.6,7 Tabu and Cortez present in their article the adaptations instituted and the short-term results of fragility fractures managed during this period. Education also needed to adapt to the changing milieu.8 Online and distance education became a mainstay in medical education and training. Garduce, et al. present their evaluation of a hybrid method of residency education.
 The rest of the articles included in this Orthopedics special issue represent continuing efforts in scientific research in our field. They showcase contributions to the body of knowledge and experience that should prove useful to our readers and ultimately, to our patients.
 Tammy L. Dela Rosa, MD, MMedScDepartment of Orthopedics,Philippine General Hospital, University of the Philippines ManilaDepartment of Biochemistry and Molecular Biology,College of Medicine, University of the Philippines Manila
 
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Recurring infection by crayfish plague pathogen only marginally affects survival and growth of marbled crayfish

Invasive alien crayfish threaten the diversity of freshwater ecosystems and native crayfish fauna. In Europe, this is largely due to transmission of the crayfish plague to susceptible native crayfish. Many invasive species tolerate crayfish plague, but the infection still has the potential to reduce the fitness of a tolerant host due to energy trade-offs between immune response maintenance and life-history traits, such as growth and reproduction. In combination with other unfavourable conditions, such a response could alter further invasion success of an otherwise successful crayfish invader. We examined whether repeated infection with one of the most virulent haplogroups of crayfish plague agent (Aphanomyces astaci) affects growth or survival of the juvenile marbled crayfish (Procambarus virginalis). Juveniles were exposed to i) two levels of pathogen concentrations, and ii) two different feeding regimes under the higher pathogen concentration. In all performed trials, repeated infection reduced growth rates, while the combination of recurring infection and food limitation significantly increased mortality. The average energy cost of the immune response was estimated at 12.07 J/day for individuals weighing 0.3 grams. Since infections were frequent and pathogen concentrations high, results suggest that marbled crayfish is resistant to A. astaci pathogen and its survival is only affected by adding the stress of food limitation. The survival of almost half of the individuals exposed to high pathogen loads and extreme food limitation indicates that chronic infection by crayfish plague is unlikely to be an important factor impeding invasion success of the marbled crayfish, even under harsh conditions. Our results add to the growing body of evidence that marbled crayfish has potential to become one of the most successful freshwater invaders.

In search of lost fleas: reconsidering Paul-Louis Simond’s contribution to the study of the propagation of plague

AbstractPaul-Louis Simond’s 1898 experiment demonstrating fleas as the vector of plague is today recognised as one of the breakthrough moments in modern epidemiology, as it established the insect-borne transmission of plague. Providing the first exhaustive examination of primary sources from the Institut Pasteur’s 1897–98 ‘India Mission’, including Simond’s notebooks, experiment carnets and correspondence, and cross-examining this material with colonial medical sources from the first years of the third plague pandemic in British India, the article demonstrates that Simond’s engagement with the question of the propagation of plague was much more complex and ambiguous than the teleological story reproduced in established historical works suggests. On the one hand, the article reveals that the famous 1898 experiment was botched, and that Simond’s misreported its ambiguous findings for the Annales de l’Institut Pasteur. On the other hand, the article shows that, in the course of his ‘India Mission’, Simond framed rats as involved in the propagation of plague irreducibly in their relation to other potential sources of infection and not simply in terms of a parasitological mechanism. The article illuminates Simond’s complex epidemiological reasoning about plague transmission, situating it within its proper colonial and epistemological context, and argues for a new historical gaze on the rat as an ‘epidemiological dividual’, which highlights the relational and contingent nature of epidemiological framings of the animal during the third plague pandemic.

Preliminary investigation and intervention of the suspected plague outbreak in Madunga, Babati District-Tanzania

BackgroundRodents are known to be reservoirs of plague bacteria, Yesinia pestis in the sylvatic cycle. A preliminary investigation of the suspected plague outbreak was conducted in Madunga Ward, Babati District Council in Manyara Region December-2019-January 2020 Following reported two cases which were clinically suspected as showing plague disease symptoms. MethodThe commensal and field rodents were live trapped using Sherman traps in Madunga Ward, where plague suspect cases were reported and, in the Nou-forest reserve areas at Madunga Ward, Babati District Council, to assess plague risk in the area. Fleas were collected inside the houses using light traps and on the rodents ‘body after anaesthetizing the captured rodent to determine flea indices which are used to estimate the risk of plague transmission. Lung impression smears were made from sacrificed rodents to examine for possible bipolar stained Yersinia spp bacilli. ResultsA total of 86 rodents consisting of ten rodent species were captured and identified from the study sites. Nine forest rodent species were collected. Field/fallow rodent species were dominated by Mastomys natalensis. whereas domestic rodent species captured was Rattus rattus. Overall lung impression smear showed bipolar stain were 14 (16.28%) while House Flea Index (HFI) was 3.1 and Rodent Flea Index (RFI) was 1.8. ConclusionThe findings of this study have shown that, the presence of bipolar stained bacilli in lung impression smears of captured species of rodents indicates (not confirmed) possible circulation of Yesrsinia pests in rodents and the high flea indices in the area which included the most common flea species known to be plague vectors in Tanzania could have played transmission role in this suspected outbreak. The study recommends surveillance follow-up in the area and subject collected samples to the standard plague confirmatory diagnosis.

Tracking of Mammals and Their Fleas for Plague Surveillance in Madagascar, 2018-2019.

ABSTRACT.Plague, a zoonotic disease caused by the bacterium Yersinia pestis, remains a major public health threat in Madagascar. To better understand the risk of transmission to humans and to guide targeted plague prevention and control measures, a survey of Y. pestis infection and exposure in mammals and their fleas was implemented. Small mammals were captured in five districts of Madagascar ranging in levels of plague endemicity, as measured by notified cases, from none to active foci. Blood and spleen samples and fleas were collected from small mammals for the detection of anti–Y. pestis F1 antibodies by ELISA, F1 antigens by rapid diagnostic tests, and pla, caf1, and inv genes by polymerase chain reaction. Some rodent fleas were kept alive and reared in the insectary to assess susceptibility to insecticides. Blood was also collected from 15 dogs and tested for anti-F1 antibodies. A total of 557 spleens, 484 sera, and 1,539 fleas were collected from 557 rodents and shrews. Nineteen (3.4%) spleens were positive for F1 antigen, most from Toamasina (N = 13), a historical plague focus. One dog was also found seropositive in Toamasina. Twenty-two (4.5%) serologic specimens from small mammals were positive for anti-F1 antibodies. The flea index was highest in the city of Antananarivo (8.8). No flea was positive for Y. pestis DNA. Flea populations exhibited resistance to various insecticides weakening the efficacy of vector control. This study highlights the potential use of animal-based surveillance to identify the risk of plague transmission in endemic and nonendemic foci for targeted prevention and control.

Risk assessment of public health emergencies concerned in the mainland of China, September 2021

Objective To assess the risk of public health emergencies, both the indigenous ones and the imported ones, which might occur in the mainland of China in September 2021. Methods An internet based expert counsel was conducted to analyze the surveillance data of public health emergencies and priority communicable diseases in China reported through different channels, and the experts in all provincial centers for disease control and prevention attended this video conference. Results Generally speaking, it is predicted that the incidence of public health emergencies would be higher in September than August. The risk of imported cases and secondary infections of COVID-19 would continue to exist, but would be controllable. It is the high incidence season of human plague. The risk of human infection in the plague focus would still exist. The possibility of long-distance transmission of plague would not be ruled out. Sporadic cases of human infections with avian influenza or other type animal influenza might still occur, but the possibility of large-scale transmission is very low. Anthrax would be at high incidence period and clusters might still occur. With the coming of autumnal epidemic period of hand, foot and mouth disease, the incidence would increase, especially in southern provinces. Conclusion Special attention should be paid to COVID-19, and general attention should be paid to plague, human infections with avian influenza, anthrax and hand, foot and mouth disease.

Keragaman, Dominasi Tikus Silvatik, Kepadatan Pinjal dan Kewaspadaan Pes di Daerah Fokus Pes di Kecamatan Cepogo Kabupaten Boyolali

One of rodent borne diseases that exist in Indonesia is pes with flea as vector and rat as reservoir. The objective of this research were to find out the diversity, dominance of rats, the density of rat and fleas as monitoring efforts for vigilance of plague transmission. The study was conducted in September-October 2016 in Wonodoyo and Kembang Kuning village, Cepogo Sub District of Boyolali District. The research is descriptive with cross sectional approach. Samples collection were conducted by rats survey used single live trap in the silvatic area. The results showed that rats trap success in Wonodoyo village was 3.8% (38 rats) and 1,1% (11 rats) in Kembang Kuning village. Four kind of silvatic rats were Rattus exulans, R. tiomanicus, Niviventer fulvescens and Maxomys surifer. Most of the rats caught (73.68%) in Wonodoyo Village were infested with fleas, while in Kembang Kuning Village it was 27.27%. All of fleas identified as Stivalius cognatus. The specific and general flea index value of S. cognatus in Wonodoyo Village is 2.66; Kembang Kuning Village is 0.45. Early vigilance is very important to do to prevent the transmission of bubonic plague originating from silvatic rats in Cepogo District, particularly in Wonodoyo Village.