Tropical myelopathies

Infectious Myelitis

Myelitis is an extensive group of pathologies, including inflammatory, demyelinating, and infectious disorders, sometimes mimicking tumors. This article will discuss infectious myelitis, mainly the patterns of spinal cord involvement caused by each infectious agent and the contribution of magnetic resonance imaging as a major tool to establish the specific diagnosis.

Tropical spastic paraparesis

A large number of causative agents can result in spinal cord disorders in the tropics including etiologies similar to those of temperate regions such as trauma, spinal bone and disc lesions, tumors, epidural abscess, and congenital malformations. Yet infectious and nutritional disorders differ in their higher prevalence in tropical regions including Pott's disease; brucellosis; neuroborreliosis; various parasitic diseases such as schistosomiasis, neurocysticercosis, and eosinophilic meningitis. Notably, the retrovirus HTLV-1 is the causeof tropical spastic paraparesis/paraplegia or TSP. Nutritional causes of TSP include vitamin B and folate deficiencies, while endemic clusters of konzo and tropical ataxic myeloneuropathy occur in Africa, along with malnutrition and excessive consumption of cyanide-containing bitter cassava. Other toxic etiologies of TSP include lathyrism and fluorosis. Nutritional forms of myelopathy are associated often with optic and sensory neuropathy, hence the name tropical myeloneuropathies. Acute transverse myelopathy, seen in association with vaccination, infections, and fibrocartilaginous embolism of the nucleus pulposus, can be ubiquitous. Multiple sclerosis and optic myelopathy occur in the tropics but with lesser prevalence than in temperate regions. The advent of modern imaging in the tropics, including computed tomography and magnetic resonance imaging, has allowed better diagnosis and treatment of these conditions that are a frequent cause of death and disability. This chapter provides an overview of TSP emphasizing the most common causes with clues to diagnosis and effective therapy.

Delayed-onset paraparesis in Lassa fever: A case report

Lassa fever (LF) is an endemic viral hemorrhagic fever in West Africa. Among the serious complications of the disease are neurological manifestations whose spectrum is incompletely known. Here we report the case of a 61-year-old man who developed a delayed-onset paraparesis a few weeks after getting infected with Lassa virus, thereby suggesting a possible association between LF and spinal cord disorders.

Infectious Myelopathies

PURPOSE OF REVIEW

This article reviews bacterial, viral, fungal, and parasitic pathogens associated with myelopathy. Infectious myelopathies may be due to direct infection or parainfectious autoimmune-mediated mechanisms; this article focuses primarily on the former.

RECENT FINDINGS

Some microorganisms exhibit neurotropism for the spinal cord (eg, enteroviruses such as poliovirus and flaviviruses such as West Nile virus), while others are more protean in neurologic manifestations (eg, herpesviruses such as varicella-zoster virus), and others are only rarely reported to cause myelopathy (eg, certain fungal and parasitic infections). Individuals who are immunocompromised are at increased risk of disseminated infection to the central nervous system. Within the last few years, an enterovirus D68 outbreak has been associated with cases of acute flaccid paralysis in children, and emerging Zika virus infection has been concurrent with cases of acute flaccid paralysis due to Guillain-Barré syndrome, although cases of myelitis have also been reported. Associated pathogens differ by geographic distribution, with myelopathies related to Borrelia burgdorferi (Lyme disease) and West Nile virus more commonly seen in the United States and parasitic infections encountered more often in Latin America, Southeast Asia, and Africa. Characteristic CSF and MRI patterns have been identified with many of these infections.

SUMMARY

A myriad of pathogens are associated with infectious myelopathies. Host factors, geographic distribution, clinical features, CSF profiles, and MRI findings can assist in formulating the differential diagnosis and ultimately guide management.

Hereditary spastic paraplegia type 35 in a family from Mali

Variants in FA2H have been associated with a wide range of phenotypes including hereditary spastic paraplegia type 35 (SPG35); however, genetically confirmed cases have not been reported in Africa. We report here the first African family with a variant in the FA2H gene causing SPG35. Four affected siblings with consanguineous parents presented with walking difficulty at age 2-3 and progressive limb weakness. They became wheelchair-bound 2 years after disease onset. Neurological examination confirmed lower greater than upper limb weakness and atrophy, brisk reflexes throughout, and spasticity with scissor legs. The patients also had choking, urinary urgency, and mental retardation. A brain MRI showed thin corpus callosum and periventricular leucodystrophy. Testing of 58 SPG genes showed a homozygous variant in FA2H at the exon 5 donor site c.786+1G>A, which has previously been shown to cause skipping of exons 5 and 6 of the gene transcript. This variant segregated with the disease in the family. This variant has been reported previously with a similar phenotype and slow progression in a population with different background. Here, we confirm its pathogenicity and expand its genetic epidemiology. Studying diverse populations may help to increase understanding of the disease mechanism and ultimately lead to therapeutic targets.

Epidemiology of non-traumatic spinal cord injury in Uganda: a single center, prospective study with MRI evaluation

BACKGROUND

A few reliable national data concerning the etiology of non-traumatic spinal cord injury (SCI) in sub-Sahara Africa exists, mainly because of the limitations of diagnostic imaging. These are both expensive and mostly unavailable in several resource-limited settings. Only a few studies have employed the magnetic resonance imaging (MRI) in documenting non-traumatic SCI and most of these studies are from South Africa. We sought to describe the clinical presentation, MRI radiological patterns, and one-year survival among subjects with non-traumatic SCI in Uganda.

METHODS

We enrolled a prospective cohort of 103 participants with non-traumatic SCI at Mulago National Referral Hospital Kampala, Uganda in 2013-2015. Participants received standard of care management, with surgical intervention as needed, with one-year follow up. Data were analyzed using Descriptive statistics.

RESULTS

In 103 participants with non-traumatic SCI, the median (IQR) age was 37 (18, 85) years and 25% of the participants were HIV-infected. Paraplegia/paraparesis was the most common clinical presentation in 70% (n = 72). Severe disease was present in 82% (n = 85) as per American Spinal Injury Association (ASIA) scale A-C. On MRI, 50% had extradural lesions. However, bone lesions accounted for only 75% of all the extradural lesions. More than 60% of the patients had lesions that could only be diagnosed on MRI. Deaths occurred in 42% (n = 44) of participants, with the highest mortality among those with extradural lesions (60%).

CONCLUSION

The mortality following non-traumatic spinal cord injuries in Uganda is high. We demonstrated an equal distribution between extradural and intradural lesions, which differs from the historical predominance of extradural lesions. Increased utilization of MRI particularly among young age groups is needed to make a diagnosis.

Is water carriage associated with the water carrier's health? A systematic review of quantitative and qualitative evidence

Introduction

The work of carrying water falls mainly on women and children, particularly in sub-Saharan Africa and rural areas. While concerns have been raised, how water carriage is associated with health of the water carrier is not clear. The aim of this review is to summarise evidence on whether, and how, water carriage is associated with the water carrier’s health.

Methods

A systematic review of literature was conducted, searching Embase; Medline; Web of Science Social Sciences Citation Index; Web of Science Arts and Humanities Citation Index; International Initiative for Impact Evaluation website; WHO Virtual Health Sciences Library and WHO African index medicus, from inception to 8 November 2017.

Results

Forty-two studies were included. Their ability to demonstrate cause and effect relationships was limited by study design and fair or poor methodological quality. Overall, the studies suggest that water carriage is associated with negative aspects of the water carriers’ health. There is moderate quantitative and strong qualitative evidence that water carriage is associated with pain, fatigue, perinatal health problems and violence against vulnerable people, and inconclusive evidence of an association with stress or self-reported mental health and general health status.

Conclusion

In many circumstances, water carriage is a potential barrier to Sustainable Development Goal (SDG) 6 target ‘universal and equitable access to safe and affordable drinking water for all’ and SDG 3 ‘ensure healthy lives and promote well-being for all at all ages’. Efforts should focus on providing water on premises, and where this is not possible, providing water close to home and reducing risk of gender-based violence.

Encephalitis and myelitis in tropical countries: Report from the Task Force on Tropical Diseases by the World Federation of Societies of Intensive and Critical Care Medicine

Tropical diseases are those that occur primarily or solely in the tropics, and as such include infectious diseases that are particularly prevalent in hot, humid conditions. The incidence of encephalitis in tropical countries is reported to be as high as 6.34/100,000/year. The term encephalitis implies inflammation of the brain and includes the presence of encephalopathy with two and more of the following features: fever, seizures and/or focal neurological findings; a cerebrospinal fluid pleocytosis; electroencephalographic findings or abnormal neuroimaging suggestive of encephalitis. Transverse myelitis (TM) is an inflammation of the spinal cord which has a wide variety of clinical presentations depending on the degree (severity of myelin and neuronal injury) and site of spinal cord involvement. In the present article we discuss the various forms of tropical, viral encephalitides and myelitis and the diagnosis and management.

A novel mutation in KIF5A in a Malian family with spastic paraplegia and sensory loss

Hereditary spastic paraplegias (HSPs) are well‐characterized disorders but rarely reported in Africa. We evaluated a Malian family in which three individuals had HSP and distal muscle atrophy and sensory loss. HSP panel testing identified a novel heterozygous missense mutation in KIF5A (c.1086G>C, p.Lys362Asn) that segregated with the disease (SPG10). Lys362 is highly conserved across species and Lys362Asn is predicted to be damaging. This study shows that HSPs are present in sub‐Saharan Africa, although likely underdiagnosed. Increasing efficiency and decreasing costs of DNA sequencing will make it more feasible to diagnose HSPs in developing countries.

Molecular analyses reveal two geographic and genetic lineages for tapeworms, Taenia solium and Taenia saginata, from Ecuador using mitochondrial DNA

Tapeworms Taenia solium and Taenia saginata are the causative agents of taeniasis/cysticercosis. These are diseases with high medical and veterinary importance due to their impact on public health and rural economy in tropical countries. The re-emergence of T. solium as a result of human migration, the economic burden affecting livestock industry, and the large variability of symptoms in several human cysticercosis, encourage studies on genetic diversity, and the identification of these parasites with molecular phylogenetic tools. Samples collected from the Ecuadorian provinces: Loja, Guayas, Manabí, Tungurahua (South), and Imbabura, Pichincha (North) from 2000 to 2012 were performed under Maximum Parsimony analyses and haplotype networks using partial sequences of mitochondrial DNA, cytochrome oxidase subunit I (COI) and NADH subunit I (NDI), from Genbank and own sequences of Taenia solium and Taenia saginata from Ecuador. Both species have shown reciprocal monophyly, which confirms its molecular taxonomic identity. The COI and NDI genes results suggest phylogenetic structure for both parasite species from south and north of Ecuador. In T. solium, both genes gene revealed greater geographic structure, whereas in T. saginata, the variability for both genes was low. In conclusion, COI haplotype networks of T. solium suggest two geographical events in the introduction of this species in Ecuador (African and Asian lineages) and occurring sympatric, probably through the most common routes of maritime trade between the XV-XIX centuries. Moreover, the evidence of two NDI geographical lineages in T. solium from the north (province of Imbabura) and the south (province of Loja) of Ecuador derivate from a common Indian ancestor open new approaches for studies on genetic populations and eco-epidemiology.

Human T-lymphotropic virus type 1-associated myelopathy/tropical spastic paraparesis: Clinical presentation and pathophysiology

Human T-cell lymphotropic virus type 1 (HTLV-1)-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a slowly progressive neurodegenerative disorder in which lesions of the central nervous system cause progressive weakness, stiffness, and a lower limb spastic paraparesis. In some cases, polymyositis, inclusion body myositis, or amyotrophic lateral sclerosis-like syndromes are associated with HTLV-1. TSP was first described in Jamaica in 1888 and known as Jamaican peripheral neuritis before TSP was related to HTLV-1 virus, the first retrovirus being identified, and the disease is since named HAM/TSP. There is no established treatment program for HAM/TSP. Prevention is difficult in low-income patients (i.e., HTLV-1 infected breast feeding mothers in rural areas, sex workers). Thus, there is a need for new therapeutic avenues. Therapeutic approaches must be based on a better understanding, not only of clinical and clinicopathological data, but also of the pathophysiology of the affection. Consequently, a better understanding of existing or newly developed animal models of HAM/TSP is a prerequisite step in the development of new treatments.

Neurosyphilis Update: Atypical is the New Typical

Syphilis has reemerged as an important cause of neurological disease, affecting any part of the neuraxis at any stage of infection. What was once a dwindling diagnosis is now redoubling, particularly in the HIV-positive and in men who have sex with men populations. In the era of antibiotics and HIV coinfection, neurosyphilis presentations are protean, making diagnosis notoriously challenging. Advanced disease may be irreversible, and so early detection and treatment are ideal. Herein, we review recent advances in understanding neurosyphilis.

Cyclical konzo epidemics and climate variability

Konzo epidemics have occurred during droughts in the Democratic Republic of Congo (DR Congo) for >70 years, but also in Mozambique, Tanzania, and the Central African Republic. The illness is attributed to exposure to cyanide from cassava foods, on which the population depends almost exclusively during droughts. Production of cassava, a drought-resistant crop, has been shown to correlate with cyclical changes in precipitation in konzo-affected countries. Here we review the epidemiology of konzo as well as models of its pathogenesis. A spectral analysis of precipitation and konzo is performed to determine whether konzo epidemics are cyclical and whether there is spectral coherence. Time series of environmental temperature, precipitation, and konzo show cyclical changes. Periodicities of dominant frequencies in the spectra of precipitation and konzo range from 3 to 6 years in DR Congo. There is coherence of the spectra of precipitation and konzo. The magnitude squared coherence of 0.9 indicates a strong relationship between variability of climate and konzo epidemics. Thus, it appears that low precipitation phases of climate variability reduce the yield of food crops except cassava, upon which the population depends for supply of calories during droughts. Presence of very high concentrations of thiocyanate (SCN(-) ), the major metabolite of cyanide, in the bodily fluids of konzo subjects is a consequence of dietary exposure to cyanide, which follows intake of poorly processed cassava roots. Because cyanogens and minor metabolites of cyanide have not induced konzo-like illnesses, SCN(-) remains the most likely neurotoxicant of konzo. Public health control of konzo will require food and water programs during droughts. [Correction added on 26 February 2015, after first online publication: abstract reformatted per journal style]