Ethnic and HLA patterns related to multiple sclerosis in Wellington, New Zealand

Variations in the patterns of prevalence and therapy in Australasian Parkinson's disease patients of different ethnicities

Parkinson's disease (PD) is the second most common neurodegenerative disease in the elderly after Alzheimer's disease. It is expected that PD cumulative incidence will increase in the future, as there are far more people surviving into late age than there ever used to be. While most commonly idiopathic, rare forms of PD can be familial/genetic. In addition, socioeconomic, cultural and genetic factors may influence the way in which anti-parkinsonian medications are prescribed, and how patients respond to them. This review aims to highlight the potential impact of genetic variation on the epidemiology and therapeutics of PD, focusing on data from New Zealand and Australia.

Virus-Induced Demyelination: The Case for Virus(es) in Multiple Sclerosis

Multiple Sclerosis (MS) is the most common demyelinating disease of man with over 400,000 cases in the United States and over 2.5 million cases worldwide. There are over 64,000 citations in Pubmed dating back as far as 1887. Much has been learned over the past 129 years with a recent burst in therapeutic options (mostly anti-inflammatory) with newer medications in development that are neuroprotective and/or neuroreparative. However, with all these advancements the cause of MS remains elusive. There is a clear interplay of genetic, immunologic, and environmental factors that influences both the development and progression of this disorder. This chapter will give a brief overview of the history and pathogenesis of MS with attention to how host immune responses in genetically susceptible individuals contribute to the MS disease process. In addition, we will explore the role of infectious agents in MS as potential “triggers” of disease. Models of virus-induced demyelination will be discussed, with an emphasis on the recent interest in human herpesviruses and the role they may play in MS disease pathogenesis. Although we remain circumspect as to the role of any microbial pathogen in MS, we suggest that only through well-controlled serological, cellular immune, molecular, and animal studies we will be able to identify candidate agents. Ultimately, clinical interventional trials that either target a specific pathogen or class of pathogens will be required to make definitive links between the suspected agent and MS.

Multiple sclerosis in New Zealand Māori

The prevalence of MS in New Zealand in 2006 was 73.2 (age standardized per 100,000) while for those with indigenous Māori ancestry it was 3.6 times lower at 20.6. Earlier regional surveys (1968–2001) all reported much lower, or zero, prevalence for Māori than European. There was no evidence for differences in MS between those with and without Māori ancestry in either clinical features or latitude, confirming that Māori ancestry does not produce the reported increase in prevalence with latitude. It is likely that prevalence is increasing in low risk Māori; however, MS prognosis is independent of Māori ancestry.

The increasing prevalence of multiple sclerosis in New Zealand

BACKGROUND

New Zealand (NZ) has a high prevalence of multiple sclerosis (MS). Worldwide, the prevalence of MS appears to be increasing.

OBJECTIVES

To review all published prevalence studies undertaken in NZ to determine whether the prevalence of MS in NZ is increasing.

METHODS

PubMed, Medline, Scopus, Web of Knowledge, EMBASE, AMED and CINAHL were searched to identify studies reporting the prevalence of MS in NZ. Prevalence rates from the National MS Prevalence study in 2006 were compared with earlier prevalence rates for the same regions using Poisson regression.

RESULTS

Prevalence rates reported in the earlier regional studies ranged from 23.6 to 68.5/100,000 population; in the same regions in 2006, the range was 47.6-134.2/100,000 population. Prevalence rates were significantly increased in all regions studied except for the Bay of Plenty. The increase in prevalence was seen in both sexes. The sex ratio remained constant over time.

CONCLUSIONS

In studies spanning almost 40 years (1968-2006), the prevalence of MS within the same regions of NZ has significantly increased whereas the sex ratio and latitudinal gradient have remained stable.

Why does the north-south gradient of incidence of multiple sclerosis seem to have disappeared on the northern hemisphere?

The traditional view, based on numerous early studies and reviews, is that MS is particularly prevalent in temperate zones both on the northern and southern hemisphere. This uneven distribution of MS can be attributed to differences in genes and environment and their interaction. Diagnostic accuracy and case ascertainment are sources of error and have their shares in the geographical and temporal variations, and improvements in diagnostic accuracy and case ascertainment influence incidence- and prevalence rates. In addition the prevalence also depends on survival. With this meta-analysis we have focused on the trend in the incidence and sex ratio of MS through the last five decades, and we have analyzed the latitudinal distribution of MS incidence, based on a recent literature search. Our findings indicated that the prevalence and incidence rates had increased in almost all areas, but the previously reported latitudinal gradient of incidence of MS in Europe and North America could not be confirmed even when restricting the search to surveys published before 1980 or 1970. Conversely, the latitudinal gradient of prevalence rates seemed to be preserved. This apparent discrepancy can be explained by the circumstance that incidence estimates only depend on complete ascertainment for a relative short recent period of time, whereas reliable prevalence rates presuppose complete ascertainment decades back in time. A contributory explanation for the missing latitudinal gradient for incidence may be changes in environmental factors, levelling out differences in habits of life across Europe and North America, and, not least, that the interpretation of a latitudinal gradient in Europe was based primarily on prevalence studies and reviews. In addition, we observed in most regions a profound increase in female incidence of MS. The last observation should prompt epidemiological studies focusing on change in female life style.

The changing demographic pattern of multiple sclerosis epidemiology

The uneven distribution of multiple sclerosis (MS) across populations can be attributed to differences in genes and the environment and their interaction. Prevalence and incidence surveys could be affected by inaccuracy of diagnosis and ascertainment, and prevalence also depends on survival. These sources of error might play a part in the geographical and temporal variations. Our literature search and meta-regression analyses indicated an almost universal increase in prevalence and incidence of MS over time; they challenge the well accepted theory of a latitudinal gradient of incidence of MS in Europe and North America, while this gradient is still apparent for Australia and New Zealand; and suggest a general, although not ubiquitous, increase in incidence of MS in females. The latter observation should prompt epidemiological studies to focus on changes in lifestyle in females. New insights into gene-environment and gene-gene interactions complicate interpretations of demographic epidemiology and have made obsolete the idea of simple causative associations between genes or the environment and MS.

Multiple sclerosis is more prevalent in northern New Zealand than previously reported

BACKGROUND

There have been no studies of multiple sclerosis (MS) prevalence from New Zealand (NZ) in the past two decades, and only one in a northern NZ district. Our impression was that the local prevalence of MS was higher than previously published data would suggest. There is limited access to new treatments for MS in NZ.

AIMS

The present paper aims to: (i). measure the prevalence of definite and probable MS in the Bay of Plenty (BOP), a North Island province, (ii). compare this with previous NZ studies, (iii). study the profile of disability in this population-based group and (iv). determine the proportion of MS patients who receive government funding for modern drug treatment (beta-interferons).

METHODS

Patients were identified from a geographically and demographically defined area of the North Island of NZ, using multiple sources of case ascertainment and modern diagnostic criteria. All clinical records were reviewed and data were supported by a telephone interview. All patients' eligibility for -government-funded treatment with beta-interferon was considered.

RESULTS

Eighty-six patients were identified as residents in BOP, NZ, on 15 January 2001. Excluding 'possible' cases, this represented a prevalence of 50/105 (95% confidence interval 40-62/105). Half of the population-based cohort had a disability defined as 'moderate to severe' (i.e. aids needed to walk, unable to take more than a few steps, or worse). Eleven patients (13%) had a primarily progressive form of MS. Eleven patients (13%) had the relapsing--remitting form of the disease and qualified for -government-funded treatment with beta-interferon.

CONCLUSION

The prevalence of MS in the defined region was twice as high as that reported from an adjacent area, the Waikato, 20 years previous. Our data will help to update NZ prevalence statistics and are of direct relevance to current funding issues for modern treatments which, in NZ, are presently limited to a proportion of patients with relapsing- remitting disease.

Epidemiologic evidence for multiple sclerosis as an infection

The worldwide distribution of multiple sclerosis (MS) can be described within three zones of frequency: high, medium, and low. The disease has a predilection for white races and for women. Migration studies show that changing residence changes MS risk. Studies of persons moving from high- to low-risk areas indicate that in the high-risk areas, MS is acquired by about age 15. Moves from low- to high-risk areas suggest that susceptibility is limited to persons between about ages 11 and 45. MS on the Faroe Islands has occurred as four successive epidemics beginning in 1943. The disease appears to have been introduced by British troops who occupied the islands for 5 years from 1940, and it has remained geographically localized within the Faroes for half a century. What was introduced must have been an infection, called the primary MS affection (PMSA), that was spread to and from successive cohorts of Faroese. In this concept, PMSA is a single widespread systemic infectious disease (perhaps asymptomatic) that only seldom leads to clinical neurologic MS. PMSA is also characterized by a need for prolonged exposure, limited age of susceptibility, and prolonged incubation. I believe that clinical MS is the rare late outcome of a specific, but unknown, infectious disease of adolescence and young adulthood and that this infection could well be caused by a thus-far-unidentified (retro)virus.

The natural history of multiple sclerosis: a regional study with some longitudinal data

A regional survey of multiple sclerosis (MS) patients in Wellington, New Zealand in 1983 identified 245 patients, giving a prevalence (all categories included) of 72 per 100,000. Retrospective review of the history and medical records identified a poorer prognosis for disability where there was progressive onset of symptoms, secondary progression after a remitting phase, older age of onset (40 years or more), or a motor syndrome involving the limbs at presentation. In 1983 follow up data were obtained on 96 patients who were seen during a previous survey in 1968. For those with definite or probable MS, progression to severe disability (Kurtzke disability status scale (DSS) 6-9) or death (DSS 10) was seen in 26/34 with moderate disability (DSS 3-5) in 1968 and in only 5/29 with mild disability (DSS 0-2). When the analysis is confined to those with symptoms for at least five years in 1968, severe disability or death from MS occurred in 22/30 with moderate and 4/19 with mild disability (chi 2 = 10.8, p = 0.001). It is concluded that the patient's established disability level after five years of illness is a useful, but not infallible, prognostic indicator. From the follow up of the 1968 patients, the probability of MS-related mortality for a given disease duration was calculated. Using this survival distribution to adjust the disability ratings in the 1983 population, it was found that the proportion with mild disability decreased steadily with increasing disease duration, reaching 14% when the disease duration was more than 25 years.

Multiple sclerosis in Australia and New Zealand: are the determinants genetic or environmental?

The prevalence of multiple sclerosis (MS) has been recently reported from nine regions of Australia and New Zealand. There is a marked variation of prevalence with latitude. MS is seven times more common in southern New Zealand than in tropical Queensland. On current evidence, it is suggested that in both countries this variation is predominantly due to environmental rather than genetic factors.

Class II HLA antigens in multiple sclerosis

HLA typing in Wellington revealed a stronger association of multiple sclerosis with DR2 than with DQw1. The association with DQw1 appeared to be due to linkage disequilibrium of this antigen with DR2. These results, when considered in conjunction with other studies, are most easily explained by the hypothesis that susceptibility to multiple sclerosis is influenced by multiple risk factors, with DR2 being an important risk factor in Caucasoid populations.