Global Comprehensive Outlook of Hantavirus Contagion on Humans: A Review

Hantaviruses are rodent viruses that have been identified as etiologic agents of 2 diseases of humans: hemorrhagic fever with renal syndrome (HFRS) and nephropathiaepidemica (NE) in the Old World and Hantavirus pulmonary syndrome (HPS) in the New World. Orthohantavirus is a genus of sin- gle-stranded, enveloped, negative-sense RNA viruses in the family Hantaviridae of the order Bunyavi- rales. The important reservoir of Hantaviruses is rodents. Each virus serotype has its unique rodent host species and is transmitted to human beings with the aid of aerosolized virus, which is shed in urine, fae- ces and saliva and hardly by a bite of the contaminated host. Andes virus is the only Hantavirus identified to be transmitted from human-to-human and its major signs and symptoms include fever, headache, mus- cle aches, lungs filled with fluid etc. In the early 1993, this viral syndrome appeared in the Four Cor- ner location in the south western United States. The only accepted therapeutics for this virus is Ribavirin. Recently, serological examinations to identify Hantavirus antibodies have become most popular for in- vestigation among humans and rodent reservoirs.

Preparation, Standardization and Anti-plasmodial Efficacy of Novel Malaria Nosodes

Background Resistance to artemisinin and its partner drugs has threatened the sustainability of continuing the global efforts to curb malaria, which urges the need to look for newer therapies to control the disease without any adverse side effects. In the present study, novel homeopathic nosodes were prepared from Plasmodium falciparum and also assessed for their in vitro and in vivo anti-plasmodial activity. Methods Three nosodes were prepared from P. falciparum (chloroquine [CQ]-sensitive [3D7] and CQ-resistant [RKL-9] strains) as per the Homeopathic Pharmacopoeia of India, viz. cell-free parasite nosode, infected RBCs nosode, mixture nosode. In vitro anti-malarial activity was assessed by schizont maturation inhibition assay. The in vitro cytotoxicity was evaluated by MTT assay. Knight and Peter's method was used to determine in vivo suppressive activity. Mice were inoculated with P. berghei-infected erythrocytes on day 1 and treatment was initiated on the same day. Biochemical, cytokine and histopathological analyses were carried out using standard methods. Results In vitro: the nosodes exhibited considerable activity against P. falciparum with maximum 71.42% (3D7) and 68.57% (RKL-9) inhibition by mixture nosode followed by cell-free parasite nosode (62.85% 3D7 and 60% RKL-9) and infected RBCs nosode (60.61% 3D7 and 57.14% RKL-9). The nosodes were non-toxic to RAW macrophage cell line with >70% cell viability. In vivo: Considerable suppressive efficacy was observed in mixture nosode-treated mice, with 0.005 ± 0.001% parasitemia on day 35. Levels of liver and kidney function biomarkers were within the normal range in the mixture nosode-treated groups. Cytokine analysis revealed increased levels of IL-4 and IL-10, whilst a decline in IL-17 and IFN-γ was evident in the mixture nosode-treated mice. Conclusion The mixture nosode exhibited promising anti-malarial activity against P. falciparum and P. berghei. Biochemical and histopathological studies also highlighted the safety of the nosode for the rodent host. The study provides valuable insight into a novel medicament that has potential for use in the treatment of malaria.

Geographical drivers and climate-linked dynamics of Lassa fever in Nigeria

Lassa fever is a longstanding public health concern in West Africa. Recent molecular studies have confirmed the fundamental role of the rodent host (Mastomys natalensis) in driving human infections, but control and prevention efforts remain hampered by a limited baseline understanding of the disease’s true incidence, geographical distribution and underlying drivers. Here, we show that Lassa fever occurrence and incidence is influenced by climate, poverty, agriculture and urbanisation factors. However, heterogeneous reporting processes and diagnostic laboratory access also appear to be important drivers of the patchy distribution of observed disease incidence. Using spatiotemporal predictive models we show that including climatic variability added retrospective predictive value over a baseline model (11% decrease in out-of-sample predictive error). However, predictions for 2020 show that a climate-driven model performs similarly overall to the baseline model. Overall, with ongoing improvements in surveillance there may be potential for forecasting Lassa fever incidence to inform health planning.

Effects of laboratory domestication on the rodent gut microbiome

The domestication of the laboratory mouse has influenced the composition of its native gut microbiome, which is now known to differ from that of its wild ancestor. However, limited exploration of the rodent gut microbiome beyond the model species Mus musculus has made it difficult to interpret microbiome variation in a broader phylogenetic context. Here, we analyse 120 de novo and 469 public metagenomically-sequenced faecal and caecal samples from 16 rodent hosts representing wild, laboratory and captive lifestyles. Distinct gut bacterial communities were observed between rodent host genera, with broadly distributed species originating from the as-yet-uncultured bacterial genera UBA9475 and UBA2821 in the families Oscillospiraceae and Lachnospiraceae, respectively. In laboratory mice, Helicobacteraceae were generally depleted relative to wild mice and specific Muribaculaceae populations were enriched in different laboratory facilities, suggesting facility-specific outgrowths of this historically dominant rodent gut family. Several bacterial families of clinical interest, including Akkermansiaceae, Streptococcaceae and Enterobacteriaceae, were inferred to have gained over half of their representative species in mice within the laboratory environment, being undetected in most wild rodents and suggesting an association between laboratory domestication and pathobiont emergence.

Linking Zoonosis Emergence to Farmland Invasion by Fluctuating Herbivores: Common Vole Populations and Tularemia Outbreaks in NW Spain

The expansion and intensification of agriculture are driving profound changes in ecosystems worldwide, favoring the (re)emergence of many human infectious diseases. Muroid rodents are a key host group for zoonotic infectious pathogens and frequently invade farming environments, promoting disease transmission and spillover. Understanding the role that fluctuating populations of farm dwelling rodents play in the epidemiology of zoonotic diseases is paramount to improve prevention schemes. Here, we review a decade of research on the colonization of farming environments in NW Spain by common voles (Microtus arvalis) and its public health impacts, specifically periodic tularemia outbreaks in humans. The spread of this colonizing rodent was analogous to an invasion process and was putatively triggered by the transformation and irrigation of agricultural habitats that created a novel terrestrial-aquatic interface. This irruptive rodent host is an effective amplifier for the Francisella tularensis bacterium during population outbreaks, and human tularemia episodes are tightly linked in time and space to periodic (cyclic) variations in vole abundance. Beyond the information accumulated to date, several key knowledge gaps about this pathogen-rodent epidemiological link remain unaddressed, namely (i) did colonizing vole introduce or amplified pre-existing F. tularensis? (ii) which features of the “Francisella—Microtus” relationship are crucial for the epidemiology of tularemia? (iii) how virulent and persistent F. tularensis infection is for voles under natural conditions? and (iv) where does the bacterium persist during inter-epizootics? Future research should focus on more integrated, community-based approaches in order to understand the details and dynamics of disease circulation in ecosystems colonized by highly fluctuating hosts.

The niche of One Health approaches in Lassa fever surveillance and control

Lassa fever (LF), a zoonotic illness, represents a public health burden in West African countries where the Lassa virus (LASV) circulates among rodents. Human exposure hinges significantly on LASV ecology, which is in turn shaped by various parameters such as weather seasonality and even virus and rodent-host genetics. Furthermore, human behaviour, despite playing a key role in the zoonotic nature of the disease, critically affects either the spread or control of human-to-human transmission. Previous estimations on LF burden date from the 80s and it is unclear how the population expansion and the improvement on diagnostics and surveillance methods have affected such predictions. Although recent data have contributed to the awareness of epidemics, the real impact of LF in West African communities will only be possible with the intensification of interdisciplinary efforts in research and public health approaches. This review discusses the causes and consequences of LF from a One Health perspective, and how the application of this concept can improve the surveillance and control of this disease in West Africa.

Genetic Diversity of Puumala orthohantavirus in Rodents and Human Patients in Austria, 2012–2019

Puumala orthohantavirus (PUUV) has a wide distribution throughout Europe. Distinctive temporal patterns of spillover into the human population are related to population dynamics of the reservoir host, the bank vole (Clethrionomys glareolus). As the rodent host is tied to specific habitats with small individual ranges, PUUV genetic diversity is also highly correlated with geographic distance. Using sequenced portions of viral S and M segments, we determined whether geographic clusters were supported. Human cases of PUUV infections are concentrated in southeastern Austria. We detected four distinct genotypes: two genotypes of the Alpe-Adria (ALAD) lineage typically associated with southeast Europe, and two sublineages of the Central Europe (CE) lineage. One cluster of CE genotypes represents a phylogenetically distinct sublineage compared to previously reported CE clades, and extends the boundary of the CE lineage further south than previously reported.

Case Report: Spinal Subarachnoid Hemorrhage: A Rare Complication of Hemorrhagic Fever with Renal Syndrome

ABSTRACTHemorrhagic fever with renal syndrome (HFRS), caused by hantavirus, is occasionally seen in tropical areas. The virus is carried by specific rodent host species. Hemorrhagic fever with renal syndrome is characterized by renal failure and hemorrhagic manifestations, and its complications may be severe, including massive bleeding, multi-organ dysfunction, and possibly death. In this patient case, a 46-year-old woman diagnosed with HFRS initially presented with fever, impaired renal function, and thrombocytopenia. Four days after symptom onset, the patient complained of abrupt right lower abdominal pain and numbness. Magnetic resonance imaging revealed a spinal subarachnoid hemorrhage (SAH) beyond the T7 to S2 vertebrae. No cases of spinal SAH in HFRS have been reported until now. This case demonstrates that when a patient’s symptoms are atypical, bleeding-related complications must be considered.

Borrelia infection in rodent host has dramatic effects on the microbiome of ticks

BackgroundVector-borne diseases remain major causes of human morbidity and mortality. It is increasingly recognized that the community of microbes inhabiting arthropods can strongly affect their vector competence, but the role of the tick microbiome in Borrelia transmission – the cause of Lyme disease – remains unclear.ResultsHere, we use a large-scale experiment to clarify the reciprocal interactions between Borrelia afzelii and the microbiome of Ixodes ricinus, its primary vector. In contrast to other reports, we find that depletion of the bacterial microbiome in larval ticks has no effect on their subsequent acquisition of B. afzelii during blood feeding on infected mice. Rather, exposure to B. afzelii-infected hosts drives pervasive changes to the tick microbiome, decreasing overall bacterial abundance, shifting bacterial community composition, and increasing bacterial diversity. These effects appear to be independent of the acquisition of B. afzelii by ticks, suggesting they are mediated by physiological or immunological aspects of B. afzelii infection in the rodent host.ConclusionsManipulation of the microbiome of I. ricinus larvae had no effect on their ability to acquire B. afzelii. In contrast, B. afzelii infection in the mouse had dramatic effects on the composition of the gut microbiome in I. ricinus nymphs. Our study demonstrates that vector-borne infections in the vertebrate host shape the microbiome of the arthropod vector.