New Species Behind Leprosy?

There have been discussions on the role of a novel species of Mycobacterium, M. lepromatosis, in the causation of Leprosy for a long time now. In 2008, Han and colleagues (1) found the novel bacterium as the causative organism behind diffuse lepromatous leprosy. A new paper (2) published in the Proceedings of the National Academy of Sciences (PNAS) has further strengthened the premise of a novel species causing leprosy by conducting a whole genome study.

The concept that Mycobaterium leprae is the only causative organism behind the disfiguring disease which has almost been eliminated from many parts of the world, now stands challenged by the emergence of this new evidence. The contribution of this new species to the overall case load and what implications it holds for public health approaches to control the disease in the long run needs to be reexamined.
The new paper, by Singha et al, has isolated Mycobacterium lepromatosis from the skin lesions of a patient suffering from diffuse lepromatous leprosy and has conducted a whole genome sequencing, followed by comparison with that of the Mycobacterium leprae, to establish the unique identities of the two different organisms.

References:

1. Han XY, Seo YH, Sizer KC, Schoberle T, May GS, Spencer JS, Li W, Nair RG. A new _Mycobacterium_ species causing diffuse lepromatous leprosy. Am J Clin Pathol. 2008 Dec;130(6):856-64. doi: 10.1309/AJCPP72FJZZRRVMM.
2. Singha P, Benjaka A, Schuenemannb VJ, Herbigb A, et al. Insight into the evolution and origin of leprosy bacilli from the genome sequence of Mycobacterium lepromatosis. PNAS. March 18, 2015. doi: 10.1073/pnas.1421504112.

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Novel Tick-Borne Anaplasma Maybe Transmitted to Human from Infected Goats

A new study from China, published in the Lancet Infectious Diseases journal, contends that a novel, tick-borne Anaplasmosis maybe transmitted from infected goats to human beings in contact. The abstract of the study is given below:

Summary

Background

Anaplasma phagocytophilum and Anaplasma ovis cause human infections. We investigated the potential for human pathogenicity of a newly discovered Anaplasma species infecting goats in China.

Methods

We collected blood samples from patients with a history of tick bite in the preceding 2 months at Mudanjiang Forestry Central Hospital of Heilongjiang Province from May 1, to June 10, 2014, to detect the novel Anaplasma species by PCR. We inoculated positive samples into cell cultures. We characterised the isolated pathogen by morphological and phylogenetic analyses. We tested serum antibodies by indirect immunofluorescence assay.

Findings

28 (6%) of 477 patients assessed were infected with the novel Anaplasma species according to PCR and sequencing. We isolated the pathogen in vitro from three patients. Phylogenetic analyses of rrs, gltA, groEL, msp2, and msp4 showed that the pathogen was distinct from all known Anaplasmaspecies. We provisionally nominate it “Anaplasma capra”. 22 (92%) of 24 patients with data available had seroconversion or a four-fold increase in antibody titres. All 28 patients developed non-specific febrile manifestations, including fever in 23 (82%), headache in 14 (50%), malaise in 13 (46%), dizziness in nine (32%), myalgia in four (14%), and chills in four (14%). Additionally, ten (36%) of 28 patients had rash or eschar, eight (29%) had lymphadenopathy, eight (29%) had gastrointestinal symptoms, and three (11%) had stiff neck. Five patients were admitted to hospital because of severe disease. Six (35%) of 17 patients with data available had high hepatic aminotransferase concentrations.

Interpretation

The emergence of “A capra” as a cause of human disease suggests that individuals living in or travelling to endemic regions in northern China should take precautions to reduce their risk of exposure to this novel tick-borne pathogen.

Reference

Li H, Zheng Y-C, Ma L, et al. Human infection with a novel tick-borne_Anaplasma_ species in China: a surveillance study. Lancet InfectiousDiseases. Published Online: 29 March 2015. DOI:http://dx.doi.org/10.1016/S1473-3099(15)70051-4. Available at: LINK

New PLoS NTD Paper on Endemic Canine Rabies

Abstract

Background

Rabies is a notoriously underreported and neglected disease of low-income countries. This study aims to estimate the public health and economic burden of rabies circulating in domestic dog populations, globally and on a country-by-country basis, allowing an objective assessment of how much this preventable disease costs endemic countries.

Methodology/Principal Findings

We established relationships between rabies mortality and rabies prevention and control measures, which we incorporated into a model framework. We used data derived from extensive literature searches and questionnaires on disease incidence, control interventions and preventative measures within this framework to estimate the disease burden. The burden of rabies impacts on public health sector budgets, local communities and livestock economies, with the highest risk of rabies in the poorest regions of the world. This study estimates that globally canine rabies causes approximately 59,000 (95% Confidence Intervals: 25-159,000) human deaths, over 3.7 million (95% CIs: 1.6-10.4 million) disability-adjusted life years (DALYs) and 8.6 billion USD (95% CIs: 2.9-21.5 billion) economic losses annually. The largest component of the economic burden is due to premature death (55%), followed by direct costs of post-exposure prophylaxis (PEP, 20%) and lost income whilst seeking PEP (15.5%), with only limited costs to the veterinary sector due to dog vaccination (1.5%), and additional costs to communities from livestock losses (6%).

Conclusions/Significance

This study demonstrates that investment in dog vaccination, the single most effective way of reducing the disease burden, has been inadequate and that the availability and affordability of PEP needs improving. Collaborative investments by medical and veterinary sectors could dramatically reduce the current large, and unnecessary, burden of rabies on affected communities. Improved surveillance is needed to reduce uncertainty in burden estimates and to monitor the impacts of control efforts.

Author Summary

Rabies is a fatal viral disease largely transmitted to humans from bites by infected animals—predominantly from domestic dogs. The disease is entirely preventable through prompt administration of post-exposure prophylaxis (PEP) to bite victims and can be controlled through mass vaccination of domestic dogs. Yet, rabies is still very prevalent in developing countries, affecting populations with limited access to health care. The disease is also grossly underreported in these areas because most victims die at home. This leads to insufficient prioritization of rabies prevention in public health agendas. To address this lack of information on the impacts of rabies, in this study, we compiled available data to provide a robust estimate of the health and economic implications of dog rabies globally. The most important impacts included: loss of human lives (approximately 59,000 annually) and productivity due to premature death from rabies, and costs of obtaining PEP once an exposure has occurred. The greatest risk of developing rabies fell upon the poorest regions of the world, where domestic dog vaccination is not widely implemented and access to PEP is most limited. A greater focus on mass dog vaccination could eliminate the disease at source, reducing the need for costly PEP and preventing the large and unnecessary burden of mortality on at-risk communities.

Reference:

Hampson K, Coudeville L, Lembo T, Sambo M, Kieffer A, et al. (2015) Estimating the Global Burden of Endemic Canine Rabies. PLoS Negl Trop Dis 9(4): e0003709. doi:10.1371/journal.pntd.0003709. Available from: LINK

Human Norovirus: Can it spread from dogs?

A recent article published in the Journal of Clinical Microbiology suggests that some dogs can mount an immune response against Human Norovirus. making them potential reservoirs and sources for this virus which has been implicated in a number of gastroenteritis outbreaks of late, most prominently amongst cruise ship passengers and crews.

However, this is too early to jump to conclusions about zoonotic implications of Norovirus disease as there are several conditions which need to be further fulfilled before a causal implication can be established.

The abstract states:

Although HuNoV RNA was not identified in stool samples from 248 dogs, serological evidence of previous exposure to HuNoV was obtained in 43/325 canine serum samples. Remarkably, canine seroprevalence to different HuNoV genotypes mirrored the seroprevalence in the human population. Though entry and replication within cells has not been demonstrated, the canine serological data indicates that dogs produce an immune response to HuNoV, implying productive infection. In conclusion this study reveals zoonotic implications for HuNoV, and to elucidate the significance of this finding, further epidemiological and molecular investigations will be essential.

Reference:
Caddy SL, de Rougemont A, Emmott E, El-Attar L, Mitchell JA, Hollinshead M,Belliot G, Brownlie J, Le Pendu J, Goodfellow I. Evidence for human norovirusinfection of dogs in the UK. J Clin Microbiol. 2015 Apr 1. pii: JCM.02778-14.[Epub ahead of print] PubMed PMID: 25832298.