Human Transmission Research Articles

Environmental, socioeconomic, and sociocultural drivers of monkeypox transmission in the Democratic Republic of the Congo: a One Health perspective

BackgroundMonkeypox (mpox) is an emerging zoonotic disease that has persistently impacted public health in endemic regions of West and Central Africa for over half a century. The Democratic Republic of the Congo (DRC) remains one of the countries most affected. Understanding the risk factors for disease transmission from a One Health perspective is of great importance in the risk assessment, prevention, and control of zoonotic diseases. Therefore, this study aimed to investigate the risk factors for human mpox transmission at the human–animal–environment interface in the DRC.MethodsEpidemiological, environmental, socioeconomic, and sociocultural data from the DRC from 2000 to 2015 were obtained from publicly available dataset. Using these data, we applied negative binomial regression model, least absolute shrinkage and selection operator regression model, and principal component analysis (PCA) to identify key environmental, socioeconomic, and sociocultural factors contributing to mpox transmission. Moreover, a grey prediction model GM (1, n) was constructed to predict the epidemic trend of mpox post-2015 and validated using suspected mpox case data in the DRC from 2016 to 2021, sourced from the United States Centers for Disease Control and Prevention.ResultsBetween 2000 and 2021, a total of 43,628 suspected mpox cases were reported in the DRC, with a peak of 6216 cases in 2020. From 2016 to 2021, suspected cases accounted for over half (24,379/43,628, 55.9%) of the total reported during the 2000–2021 period. The proportion of primary forest [incidence rate ratio (IRR): 1.023, 95% confidence interval (CI): 1.018–1.027], index of economic well-being (IRR: 1.046, 95% CI: 1.039–1.052), and mean annual precipitation (IRR 1.040, 95% CI: 1.031–1.049) were positively associated with mpox incidence. PCA identified five principal components, explaining 69% of the variance in the environmental, socioeconomic, and sociocultural variables. The first component was characterized by socioeconomic factors. The GM (1, n) model, based on the proportion of primary forest, index of economic well-being, and mean annual precipitation, predicted the epidemic trend (revealed relative error: 2.69).ConclusionsBoth socioeconomic and environmental factors play important roles in mpox transmission. Our study further highlighted the importance of considering the interconnectedness among humans, animals, and the environment, and treating these factors as a whole to explain the transmission and emergence of mpox outbreaks in the DRC according to the One Health concept.

Avian model systems to understand human herpesvirus replication, transformation, reactivation, and transmission

Avian model systems to understand human herpesvirus replication, transformation, reactivation, and transmission

Detection of tick-borne pathogens in blood-fed ticks from animals across nine Asian countries.

Surveillance systems against novel tick-borne diseases are significant for global health. Climate and other environmental changes have contributed to an expanding range of ticks and tick-borne diseases. Areas in Asia constitute key areas of emerging infectious diseases. Through analysis of blood-fed ticks, collected from various animals living in the natural environment, we suggest that tick-borne pathogens may harbor animals and environment and have potential risk of transmission in humans. Understanding the distribution of tick-borne pathogens requires cooperative studying and, thus, can construct standardized surveillance systems.

Investigation of diabetes mellitus transmission in humans by using time delay tool and numerical treatment approach

Investigation of diabetes mellitus transmission in humans by using time delay tool and numerical treatment approach

Risk factors associated with human Mpox infection: a systematic review and meta-analysis

BackgroundMpox emerged as a significant global public health concern during the 2022–2023 outbreak, impacting populations in both endemic and non-endemic countries. This study reviews and synthesises evidence on the risk...

Molecular epidemiology of Hepatitis E virus among humans in the Niger Republic, 2017-2023.

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis, responsible for large outbreaks in resource limited countries. The virus belongs to the genus Orthohepevirus which is subdivided into eight distinct genotypes (HEV-1 to HEV-8). Human disease transmission is mostly through the faecal-oral route. However, zoonotic transmission could also occur. In the Niger Republic, the first documented HEV outbreak was recorded in 2017 around displaced persons camps in the Diffa region across the Lake Chad basin, resulting in 736 confirmed cases and 38 (1.9%) deaths. Since then, sporadic cases were annually reported despite the lack of specific surveillance. Overall, from 2017 to 2023, a total of 2820 HEV suspected cases were sampled, out of which 906 (32.12%) were confirmed positive by either qRT-PCR and/or IgM ELISA. Out of the 21 characterized isolates, we identified 15 sequences belonging to the genotype 1e and 6 sequences to the genotype 2b. The newly characterized sequences from Niger clustered with those circulating in neighbouring countries, suggesting a cross-border virus circulation. The co-circulation of HEV genotypes 1 and 2 is an indicator of the probable virus transmission through contaminated water sources. Thus, there is a crucial need to improve the preparedness and implement an active and integrated community-based surveillance. This should include field testing for rapid detection and characterization of HEV as well as actions for disease containment, strengthening of hygiene measures and community-based sensitization for behavioural changes.

SOLARIS project: a portable 3D-printed bioaerosol sampler for environmental bacterial collection.

Bioaerosols, a subset of aerosols released from the biosphere, can carry pathogens, and include particles with diameters from nanometres to a few micrometres. They can remain suspended indoors and travel significant distances. Bioaerosol studies play a vital role in public health, as bioaerosols are an effective route for human and animal pathogen transmission, especially in animal production and handling facilities, which are considered hotspots for the emergence of zoonotic pathogens. The 'One Health' approach, which interconnects human, animal and environmental health, underscores the need for robust biomonitoring and biosurveillance systems. We introduce the SOLARIS project, a novel bioaerosol sampler manufactured through three-dimensional printing with a biocompatible material. Our sampler is compact, portable and uses a liquid collection medium, increasing bioefficiency. Our sampler's laboratory testing demonstrated the successful separation of viable Escherichia coli bacteria from artificially generated bioaerosols. Collected samples were found suitable for downstream analysis methods such as culturing, mass spectrometry, molecular detection and electron microscopy. A field trial at a swine facility was performed, in which Clostridioides difficile spores were successfully collected from bioaerosols and identified using microbiological and molecular methods, reinforcing our sampler's utility and emphasizing the significance of incorporating aerosol samples in research studies within the One Health approach.

Superficial Cutaneous Sporotrichosis, Report of a Case with Adequate Response

Introduction: Sporotrichosis is a mycosis caused by the fungus of the genus Sporothrix, of which six species related to human sporotrichosis are recognized, being the S. schenkii complex the most related to transmission in humans. The entry of the agent occurs by contact between the injured skin and the fungal spores, subsequently the fungal conidia are deposited in the host tissue and when introduced, become yeast. The fungus, now in its yeast-like phase, may remain at the site of entry or spread to other sites following the lymphatic vessels (1). Case presentation: We present the case of a 62-year-old male patient with arterial hypertension of 6 years of evolution, gardener, who came to our unit due to the presence of blistering and ulcerative lesions (image 1) on the foot and ipsilateral thigh. He received empirical treatment by private means with acyclovir cream and oxytetracycline, due to the characteristics of the lesions he was treated for herpes zoster with standard dose Acyclovir, he was seen in an outpatient internal medicine clinic one week later. Due to persistence of lesions and scarce reduction in symptomatology, a diagnosis was made according to clinical history, dermal and biochemical pattern of probable mycosis, with emphasis on sporotrichosis or “gardener's disease”, initiating treatment with itraconazole fractional dose for four weeks, with weekly follow-up of the case. Conclusions: At present, the diagnosis of S. schenkii, is of exclusion, in the face of predominant agents in the region. The most frequent clinical forms in humans are the fixed cutaneous form, the lymphatic form and the disseminated form; the latter has a poor prognosis due to its association with immunodeficiencies. Our case is an example of timely diagnosis with appropriate initial azole-based treatment, reflecting a successful case response, inviting the clinician to early integration

Transmission patterns of hepatitis E virus.

Hepatitis E virus (HEV) causes sporadic cases in industrialized countries and endemic outbreaks in areas with lower sanitation standards. The wide host reservoir of HEV makes it a potential source of new zoonotic transmission and dissemination in humans. Thus, the perception of HEV as a confined ailment has shifted to one of global concern. Considering HEV's environmental stability and heterogeneity in the host range of HEV's genotypes, various transmission pathways and sources for HEV infections are plausible. Here, we provide an overview on HEV's transmission routes and discuss the role of HEV as a foodborne zoonosis, as well as preventive measures and open research questions.

Triatoma venosa and Panstrongylus geniculatus challenge the certification of interruption of vectorial Trypanosoma cruzi transmission by Rhodnius prolixus in eastern Colombia.

Reactivation of Trypanosoma cruzi transmission by native vectors with different domiciliation capabilities is a major concern for Chagas disease control programs. T. cruzi transmission via intra-domestic Rhodnius prolixus was certified as interrupted by the Pan American Health Organization in Miraflores municipality (Boyacá, Colombia) in 2019. However, Triatoma venosa, a native vector infected with T. cruzi has been increasingly found inside human dwellings across rural areas. In this study, the aim was to describe the eco-epidemiological aspects of T. cruzi transmission in the rural area of Miraflores. For this, we designed a comprehensive, multi-faceted study in 6 rural villages and performed: (i) A cross-sectional serological and molecular study enrolling 155 people and 58 domestic dogs living within 80 households, (ii) a domestic entomological survey, (iii) a determination of the natural infection and blood meal source in collected triatomine bugs, and (iv) an evaluation of synanthropic mammal infection by parasitological and molecular tools. The T. cruzi seroprevalence rates in humans and dogs were 9.03% (14/155) and 22.4% (13/58), respectively. Most infected humans were adults between the ages of 55 and 85 years old. No evidence of T. cruzi DNA was found using qPCR in human blood samples, but we found high parasitemia levels in the infected dogs. In total, 38 triatomine bugs were collected inside dwellings and peridomestic areas: 68.4% (26/38) Triatoma venosa, 29% (11/38) Panstrongylus geniculatus, and 2.6% (1/38) P. rufotuberculatus. Natural infection prevalence was 88% (22/25) for T. venosa, 100% (12/12) for P. geniculatus, and 100% (1/1) P. rufotuberculatus: only TcI was found. No evidence of R. prolixus was found in the area. Two feeding sources were identified in T. venosa (humans and cats), while P. geniculatus fed on cows and bats. Lastly, seven D. marsupialis were captured in peridomestic areas, three were infected with T. cruzi (TcI). The results suggest the existence of T. cruzi transmission cycle between triatomines, dogs, and opossums representing a risk of infection for the human population in rural areas of Miraflores. Despite PAHO declaring Miraflores municipality, Colombia an area of T. cruzi transmission interruption in 2019, this study documents evidence of a secondary vector establishing in domestic settings. T. venosa entomological surveillance is warranted to evaluate prospective human transmission risk in an otherwise 'no-risk' perceived Chagas disease region.

Receptor binding, structure, and tissue tropism of cattle-infecting H5N1 avian influenza virus hemagglutinin.

The ongoing circulation of highly pathogenic avian influenza (HPAI) A (H5N1) viruses, particularly clade 2.3.4.4b strains, poses a significant threat to animal and public health. Recent outbreaks in cattle highlight concerns about cross-species transmission and zoonotic spillover. Here, we found that the hemagglutinin (HA) protein from a cattle-infecting H5N1 virus has acquired slight binding to human-like α2-6-linked receptors while still exhibiting a strong preference for avian-like α2-3-linked sialic acid receptors. Immunohistochemical staining revealed HA binding to bovine pulmonary and mammary tissues, aligning with clinical observations. HA also binds effectively to human conjunctival, tracheal, and mammary tissues, indicating a risk for human transmission, notably in cases of conjunctivitis. High-resolution cryo-electron microscopy (cryo-EM) structures of this H5 HA in complex with either α2-3 or α2-6 receptors elucidate the molecular mechanisms underlying its receptor-binding properties. These findings provide critical insights into the tropism and transmission potential of this emerging pathogen.

The haemagglutinin gene of bovine-origin H5N1 influenza viruses currently retains receptor-binding and pH-fusion characteristics of avian host phenotype

ABSTRACT Clade 2.3.4.4b H5N1 high pathogenicity avian influenza virus (HPAIV) has caused a panzootic affecting all continents except Australia, expanding its host range to several mammalian species. In March 2024, H5N1 HPAIV was first detected in dairy cattle and goats in the United States. Over 891 dairy farms across 16 states have tested positive until 25 December 2024, with zoonotic infections reported among dairy workers. This raises concerns about the virus undergoing evolutionary changes in cattle that could enhance its zoonotic potential. The Influenza glycoprotein haemagglutinin (HA) facilitates entry into host cells through receptor binding and pH-induced fusion with cellular membranes. Adaptive changes in HA modulate virus-host cell interactions. This study compared the HA genes of cattle and goat H5N1 viruses with the dominant avian-origin clade 2.3.4.4b H5N1 in the United Kingdom, focusing on receptor binding, pH fusion, and thermostability. All the tested H5N1 viruses showed binding exclusively to avian-like receptors, with a pH fusion of 5.9, outside the pH range associated with efficient human airborne transmissibility (pH 5.0–5.5). We further investigated the impact of emerging HA substitutions seen in the ongoing cattle outbreaks, but saw little phenotypic difference, with continued exclusive binding to avian-like receptor analogues and pHs of fusion above 5.8. This suggests that the HA genes from the cattle and goat outbreaks do not pose an enhanced threat compared to circulating avian viruses. However, given the rapid evolution of H5 viruses, continuous monitoring and updated risk assessments remain essential to understanding virus zoonotic and pandemic risks.

Sixty-five draft genome sequences of Campylobacter coli and Campylobacter jejuni from table egg layer chickens.

We present the draft genomic sequences of 65 isolates of Campylobacter spp. (38 Campylobacter coli and 27 Campylobacter jejuni) isolated from table egg-layer chickens, which are not generally associated with human transmission. Up to this time, there are no publicly available genomic sequences of Campylobacter isolated from laying hens.

Animal Models in Influenza Research.

Animal model systems for human and animal influenza virus infection and transmission have been established to address research questions which cannot be addressed using in vitro models. Several animal models are widely used, including mice, guinea pigs, hamsters, ferrets, pigs, poultry, nonhuman primates, and others. Each animal model has its own strength and weaknesses, which should be taken into consideration to select the appropriate animal model to use. This chapter will describe standard protocols relevant for in vivo experiment, including procedures required prior to the start of the animal experiment and sample processing. The animal models described in this chapter are mice, hamsters, guinea pigs, ferrets, pigs, and chickens.

Serological evidence of Crimean-Congo haemorrhagic fever in domestic animals from eight regions of Namibia.

Crimean-Congo haemorrhagic fever (CCHF) is a viral zoonotic disease endemic to regions of Africa, the Balkans, the Middle East, and Asia, with increasing reports of cases in southern Europe. Human transmission occurs primarily through the bite of infected ticks and by body fluids from infected human. Crimean-Congo haemorrhagic fever virus (CCHFV) affects a broad host range, including both domestic and wild vertebrates. Recent studies have suggested a potential susceptibility of companion animals, posing an additional threat to public health. In the present study, the presence of CCHFV antibodies was evaluated by screening 374 dog and 238 cat serum samples collected from eight Namibian regions using a commercial enzyme-linked immunosorbent assay. Overall, dogs (11.50%) showed significantly higher odds of seropositivity (OR = 7.60; 95% CI = 3.02 - 25.51; p-value < 0.001) compared to cats (1.68%). Most of the positive dogs and all positive cats originated from the Kunene and Hardap regions. No other factors were found to affect seroprevalence. The limited development of farming systems in these regions, combined with the higher roaming activity of dogs, may suggest a greater exposure risk to wild animals or infected ticks. Tick species of the genus Hyalomma are not commonly reported to infest dogs in Namibia, and other tick species may also be involved in transmission. The detection of CCHFV antibodies in dogs and cats in Namibia should be considered by public health authorities as a potential threat, warranting further investigation to identify infection sources and risk factors. While the level and duration of viremia in companion animals, as well as their actual infectivity, remain unknown, efforts should focus on reducing contact between domestic pets, livestock, and wild animals, as well as regular prophylactic tick treatment of pets to prevent or minimise tick infestations.

An epidemiological study of malaria parasites among long–tailed macaques (Macaca fascicularis), pig–tailed macaques (Macaca nemestrina) and silver–leaf monkeys (Trachypithecus cristatus) in Sumatra Region, Indonesia

Objective: To ascertain the prevalence and distribution of malaria parasites among the three monkeys species from three provinces in Sumatra Island, Indonesia. Methods: Infections with Plasmodium spp. were determined morphologically from the blood smears which were stained with Giemsa solution and molecularly through nested polymerase chain reaction (PCR) in DNA samples from 68 primates, which were captured at three locations: Jambi (Bungo district), Bengkulu (Muko-Muko district), and Riau Islands (Lingga district). Results: Out of 68 samples analyzed, 46 were positive for various Plasmodium species, including Plasmodium knowlesi, Plasmodium cynamolgi, Plasmodium inui, and Plasmodium coatneyi. Over one-third of the population exhibited multiple infections, with Plasmodium inui being the most predominant strain. Conclusions: The high prevalence of multiple malaria infections in monkeys, coupled with the rising reports of primate malaria cases in human raises questions about the potential for human transmission. These findings emphasize the necessity for ongoing monitoring and endeavors to comprehend and alleviate the risk of zoonotic malaria transmission, particularly in areas experiencing environmental changes.

Drug resistance detection of canine origin Escherichia coli in China and inhibition by genipin.

Zoonotic transmission from pets to their owners is a major health problem. It is important to determine and control the drug resistance in pets to mitigate risks of human transmission. In this work, the current prevalence of multi-drug resistance (MDR) and resistance gene in Escherichia coli (E. coli) derived from dogs in nine cities across various regions of China initially evaluated using microfluidic dilution methods and polymerase chain reaction (PCR) technology. To control antibiotic resistance, genipin as natural product was used to combat MDR E. coli. Finally, the synergistic effect of genipin and norfloxacin on MDR E. coli was studied using time-kill curves to retard the resistance spread. A total of 126 E. coli strains were isolated from 154 collected fecal samples of dogs. Minimum inhibitory concentrations (MIC) results revealed that the highest detection rate of MDR E. coli appeared in Zhengzhou at 90.9%, and the lowest in Shenyang at 10.0%. The results of drug resistance gene testing indicated that the blaTEM gene had the highest detection rate (99.2%), then tetA and blaCTX-M-1, whose detection rates all exceed 50%. Furthermore, the MIC of genipin against MDR E. coli was found to be 4096μg/mL, and genipin at ½ MIC demonstrated significant inhibition on MDR E. coli within 6hours. Finally, the combination of ¼ MIC genipin with ½ MIC norfloxacin showed partial synergistic inhibitory effect on MDR E. coli. Our findings suggest that although antibiotic resistance in canine origin E. coli varies across different regions of China, it remains concerning, and genipin shows potential as a treatment option for MDR E. coli infections.

Rapid human movement and dengue transmission in Bangladesh: a spatial and temporal analysis based on different policy measures of COVID-19 pandemic and Eid festival.

Rapid human movement plays a crucial role in the spatial dissemination of the dengue virus. Nevertheless, robust quantification of this relationship using both spatial and temporal models remains necessary. This study aims to explore the spatial and temporal patterns of dengue transmission under various human movement contexts. We obtained district-wise aggregated dengue incidence data from the Management Information System,Directorate General of Health Services of Bangladesh. The stringency index (SI), along with eight individual policy measures (from the Oxford Coronavirus Government Response Tracker database) and six mobility indices (as measured by Google's Community Mobility Reports) were obtained as human movement indicators. A multi-step correlative modelling approach, including various spatial and temporal models, was utilized to explore the associations of dengue incidence with the SI, fourteen human movement indices and the Eid festival. The global Moran's I indicated significant spatial autocorrelation in dengue incidence during the pre-pandemic (Moran's I: 0.14, P < 0.05) and post-pandemic periods (Moran's I: 0.42, P < 0.01), while the pandemic period (2020-2022) showed weaker, non-significant spatial clustering (Moran's I: 0.07, P > 0.05). Following the pandemic, we identified the emergence of new dengue hotspots. We found a strong negative relationship between monthly dengue incidence and the SI (rspearman: -0.62, P < 0.01). Through the selection of an optimal Seasonal autoregressive integrated moving average model, we observed that the closure of public transport (β = -1.66, P < 0.10) and restrictions on internal movement (β = -2.13, P < 0.10) were associated with the reduction of dengue incidence. Additionally, observed cases were substantially lower than predicted cases during the period from 2020 to 2022. By utilising additional time-series models, we were able to identify in 2023 a rise in dengue incidence associated with the Eid festival intervention, even after adjusting for important climate variables. Overall, rapid human movement was found to be associated with increased dengue transmission in Bangladesh. Consequently, the implemention of effective mosquito control interventions prior to large festival periods is necessary for preventing the spread of the disease nationwide. We emphasize the necessity for developing advanced surveillance and monitoring networks to track real-time human movement patterns and dengue incidence.

Environmental contamination of Opisthorchis viverrini eggs and its impact ontransmission control in rural northeast Thailand.

Environmental contamination with Opisthorchis viverrini eggs significantly impacts on opisthorchiasis transmission and disease control. This study assessed O. viverrini egg contamination in underwater sediments from canals and aimed to reduce O. viverrini transmission in egg-positive and downstream communities by controlling human opisthorchiasis in endemic area of Northeast Thailand. Sediment samples from 14 sites in UdonThani municipality were determined for O. viverrini eggs. Human fecal samples and fish were examined for opisthorchiasis and metacercaria infection, respectively. Water samples were analysed for faecal coliforms bacteria. From 2017 to 2023, transmission control efforts were evaluated by monitoring changes in human and fish infection rates. In 2017 and 2018, O. viverrini eggs were found in canal sediments at 153 and 86 eggs/liter, respectively. Human opisthorchiasis prevalence was 5.3%, with cyprinoid fish showing a 25.0% infection rate (11.6 cysts/infected fish) and significant fecal contamination (>5,500 CFU/100 ml). Conversely, egg-negative sites showed a 0.5% human infection rate and no metacercariae were found. After health interventions (2019 to 2023), O. viverrini eggs were not detected in sediments from canals, resulting in a significant reduction in human opisthorchiasis prevalence to 0.9% at the previously egg-positive site and from 12.2% to 1.7% in downstream communities (p < 0.001). Additionally, the prevalence of metacercariae in cyprinoid fish decreased from 11.4% (7.6 cysts/infected fish) to 4.5% (2.4 cysts/infected fish), indicating reduced transmission. The presence of O. viverrini eggs in sediment was associated to human opisthorchiasis transmission and demonstrated the significant effectiveness of health interventions in controlling the disease.

Campylobacter jejuni/coli Infection: Is It Still a Concern?

Campylobacteriosis is a leading cause of infectious diarrhea and foodborne illness worldwide. Campylobacter infection is primarily transmitted through the consumption of contaminated food, especially uncooked meat, or untreated water; contact with infected animals or contaminated environments; poultry is the primary reservoir and source of human transmission. The clinical spectrum of Campylobacter jejuni/coli infection can be classified into two distinct categories: gastrointestinal and extraintestinal manifestations. Late complications are reactive arthritis, Guillain–Barré syndrome, and Miller Fisher syndrome. In the pediatric population, the 0–4 age group has the highest incidence of campylobacteriosis. Regarding the use of specific antimicrobial therapy, international guidelines agree in recommending it for severe intestinal infections. Host factors, including malnutrition, immunodeficiency, and malignancy, can also influence the decision to treat. The Centers for Disease Control and Prevention (CDC) has identified antibiotic resistance in Campylobacter as a ‘significant public health threat’ due to increasing resistance to FQs or macrolides. Although numerous vaccines have been proposed in recent years to reduce the intestinal colonization of poultry, none have shown sufficient efficacy to provide a definitive solution.