Non-communicable diseases outweigh communicable diseases

Prof. Lakshman Dissanayake-Department of Demography, University of Colombo

Mortality in Sri Lanka has declined substantially over the latter half of the 20th century and then well into the new millennium. Life expectancy at birth for males and females were 32.7 and 30.7 years, for the 1920-22 period. By 2000-02, the figures have risen to 68.8 years for males and 77.2 years for females. The projected figures show that male life expectancy is expected to reach 72.3 years while female life expectancy will be 82.5 years by 2026.

The decline of mortality during the past 100 years has occurred at all ages and for both sexes. However, the extent and the timing of improvement have varied. Percentage decreases in rates of mortality have been highest for infants and children. Rapidity of improvement has been greater for females especially after 1960s.

Crude death rate

Evidence suggests crude death rate has continued to decline from the mid 1970s and then stabilising around 6 deaths per 1000 population from the beginning of the 1980 decade. During this stage, it appears that heart diseases, cancer, stroke and diabetes become increasingly prominent gradually displacing pandemics of infection as causes of morbidity and mortality. In Sri Lanka, morbidity data is only available for patients seeking treatment as inpatients in government hospitals. A substantial increase in hospitalisation was observed for injury and poisoning during the period from 1980 to 2000.

Selected causes of hospital deaths between 1975 and 2000 clearly illustrate that degenerative diseases gradually replace parasitic and infectious diseases in Sri Lanka. For example, intestinal infectious diseases and tuberculosis oscillates at very low level of under 4 per 100,000 population after 1990s while ischemic heart diseases and diseases of the liver show a steady increase beyond 14 per 100,000 population. In 2007, Traumatic injuries represent the first spot in the list of leading causes of hospitalisation while highest number of hospital deaths was reported due to ischemic heart disease.

There were 606,889 hospital patients due to traumatic injuries while 4,536 deaths were reported due to ischemic heart disease. It was also apparent that 50 percent of hospital deaths due to traumatic injuries were caused by road traffic accidents which amounted to 30,420 in 2008.

The changes in life expectancy values of Sri Lanka for a 30-year time period between 1971 and 2001 show that there had been a considerable increase in female life expectancy compared to that of the males. The total as well as average annual gain in life years was more than doubled for females. However, average annual change over a 30-year period shows that the pace of mortality decline was slackening which is one of the major features of the age of degenerative and man-made diseases. Since Sri Lanka's overall life expectancy was still 72.4 in 2000-02 period, it is very much certain that Sri Lanka still cruise through the age of degenerative and man-made diseases.

Sex difference

Sri Lankan women enjoy better health status than men. The latest life expectancy figures show that the difference between male and females life expectancies was 8.4 years. This is very similar to the difference observed for Europe in 2000-05 period. The average difference observed for the Asian countries was 3.6 years and hence, Sri Lankan women seem to be enjoying better health status than women in other countries in Asia.

Some of the major factors for the sex difference in life expectancy could be attributed to the development of the health system, improved public health measures that have reduced maternal mortality, socio-economic changes that have changed female status and value of parents, both the mother and the father, or girls relative to boys.

I have found that the major causes of death for males are diseases of the circulatory system, diseases of the nervous system, diseases of the respiratory system, endocrine, nutritional and metabolic diseases, neoplasms and external causes of morbidity and mortality. After 40, men's death rate is higher at each age and the gap becomes wider, especially between 60 and 75.

Prof. Lakshman Dissanayake

According to the standard projection estimates made for Sri Lanka, median age increases from 27.9 years to 37.8 years by 2026. The elderly population (60+ years) will grow from 1.7 million in 2001 to 4.1 million in 2026, which is 141 percent increase during 25 years time period. On the other hand, child population is expected to decrease from 4.9 million in 2001 to 3.8 million in 2026, which is a 28 percent decline. Therefore, it is highly likely that the degenerative and man-made diseases to replace infectious and parasitic diseases at an increasing rate during the first 25 years in the 21st century.

Annual Health Bulletin of Sri Lanka-2003 already reported that 'the trends in mortality indicate a decrease in deaths resulting from infectious and parasitic diseases, diseases of the nervous system and sense organs and of the respiratory system whereas substantial increase in the death rates associated with diseases of the circulatory system and injury and poisoning is evident'. In this context, there can be fundamentally three types of morbidity: Highly fatal chronic diseases of the heart, cancer and stroke, and chronic diseases involving repeated or continued medical care such as diabetes, kidney diseases, arthritis, obesity, allergies etc; accidents and predominantly traffic accidents; diseases caused by stress, such as drug dependency, mental illness, peptic ulcers, suicide tendencies etc. In such a situation, offering medical and health care facilities will be increasingly more costly and complex as it will require to deal with not only for chronic nature of the diseases but also the need of acquiring new ways of tackling the problems of survival and ageing.

Degenerative diseases

Delayed degenerative diseases and resurgence of infectious and parasitic diseases it appears that the life expectancy values in the world have been in constant rise. In 1980, the maximum life expectancy achieved was 76 years in countries such as Sweden, Norway and the Netherlands while the highest life expectancy recorded for the year 2008 was 82 years in countries like France and Italy. Life expectancy values for Sri Lanka were 68 and 74 years for 1980 and 2008. Sri Lanka's present situation is very similar to countries like United Kingdom, Italy and France in 1980. This means that Sri Lanka seems to be following the trend of the countries which were exposed to 'cardiovascular revolution' in the 1970s but with a time lag.

It is also reasonable to hypothesise that Sri Lanka will be able to achieve 80 years of life expectancy less than the number of years spent by the Western countries as Sri Lanka has already started to use imported medical technology and other health measures which can prevent or postpone degenerative diseases at the adult ages.

As in the West, Sri Lanka can expect its life expectancy to continue to grow with a continuing postponement of deaths from degenerative diseases.

Similarly, it can be anticipated mortality rates at older ages to accelerate as well. Early signs of such phenomena can be seen by examining the life expectancy figures as well as adult mortality rate (or probability of dying between age 15 and 60). Life expectancy at age 60 from the 1980s suggests that there has been a significant increasing trend which reflects the postponement of deaths beyond ages 78 and 80 for males and females, respectively.

Adult mortality rate

Adult mortality rate had declined significantly between 1990 and 2007. This means that survival chances of the ages 15 and 60 have increased and the higher death rates have been postponed to higher ages of the life span. This shows that those who have died formerly due to fatal complications as chronic disease outcome tend to survive longer. Such a phenomenon can reflect two processes: morbidity expansion or morbidity compression.

Morbidity expansion means that age-specific prevalence rates of those diseases will increase. In other words, people will survive longer but the duration that they spend in a state of sickness and disability at the end of their life span will increase. This will occur if Sri Lanka does not adopt proper health strategies to prevent or postpone degenerative and man-made diseases. However, it appears that Sri Lanka has already prepared its national policy and strategic framework for prevention and control of chronic non-communicable diseases.

The Government has therefore, aimed at promoting health and well-being of the population by preventing chronic non-communicable diseases associated with shared modifiable risk factors, providing acute and integrated long-term care for people with non-communicable diseases, and maximising their quality of life.

Although Sri Lanka has been moving away from epidemic and famine stage during the 20th century, sporadic emergence of new type of infectious and parasitic diseases can be observed with the dusk of the 20th century. Dengue fever can be named one such disease that the Sri Lankan health authorities still have not been able to control.

The most recent estimates available in this regard show that there were 19,629 such cases and 156 related deaths only during the second half of 2009. In 2010, this went up to 34,105 cases and 246 related deaths. This suggests a continuous rise of this disease in Sri Lanka.

Japanese encephalitis can be regarded as another disease that emerged as an epidemic in Sri Lanka during the latter quarter of the 20th century. It tends to be endemic in Sri Lanka and occurs sporadically throughout the year with a peak after the start of monsoon rains. Sri Lanka experienced its first epidemic of Japanese encephalitis with 410 cases and 75 deaths in 1985. This was followed by a second epidemic in 1987-88 in which 760 cases and 138 deaths were reported.

Outbreak

An outbreak of Chikungunya fever was initially reported in Sri Lanka in 1965. It originated in Colombo and spread along the south-western coastal belt during the period from May to June in 1965. Urban areas were severely affected and all age groups were involved. Chikungunya is an arboviral infection caused by a virus belonging to the Alphavirus family. It is a viral disease transmitted effectively by both Aedes aegyptii and Aedes albopictus types of mosquitoes.

It was reported that there were 37,667 Chikungunya cases in Sri Lanka during the period 2006-07. The most affected areas were from the western and north-western provinces.

Sri Lanka is currently experiencing the benefits accrued in the course of its mortality transition by cruising through various ages of the epidemiologic transition. Its population has improved its life expectations considerably over the years and expected to prolong that ascend despite impulsive resurgence of infectious and parasitic diseases.

Therefore, Sri Lanka will have the prospect to hoist its life expectancy to a level that is observed in the developed world.

Since females tend to live higher than males, the Sri Lankan elderly female population will be feminised as a result of enhancement of female survival chances. Declining mortality and morbidity will produce healthier labour force which can improve its productivity.

Since Sri Lanka has a relatively large labour force with low level of dependency at present, improved health status of its labour force surely will have a significant impact on economic development in the country.

It will create a unique opportunity for families to escape poverty and for faster economic growth, provided Sri Lanka adopts appropriate educational skill development strategies and create more employment opportunities. In one hand, it is reasonable to claim that a healthy population is a prerequisite for economic growth. On the other hand, it appears that there is a high correlation between population ageing and medical spending.

However, it is rather disability and poor health often associated with old age that is costly.

As Sri Lanka has commenced to obtain the benefits of the 'cardiovascular revolution' and other medical technology advances, its elderly population will be disability free and in good health for a considerable time in their old ages.

Therefore, it is quite reasonable to claim that good health expected among the elderly population can save money and hence healthy-ageing needs to be regarded as an important component of the Sri Lanka's development agenda.

The mathematics of a heartbeat could save lives

What we perceive as the beating of our heart is actually the co-ordinated action of more than a billion muscle cells. Most of the time, only the muscle cells from the larger heart chambers contract and relax.

But when the heart needs to work harder it relies on back-up from the atrial muscle cells deep within the smaller chambers (atria) of the heart.

The health of these 'high-performance' atrial cells relies on specific concentrations of cellular calcium. Now, for the first time, scientists at The University of Nottingham have produced a mathematical model of calcium activity within the atrial heart cell which will significantly improve our chances of treating heart disease and stroke.

This breakthrough, which takes scientists into a world of cell activity currently beyond the scope of imaging technology, has just been published in the journal

Proceedings of the National Academy of Sciences (PNAS).

Dr Rüdiger Thul, a lecturer in applied mathematics in the School of Mathematical Sciences, said: "This new model provides clinically relevant insights into the initiation and propagation of sub-cellular calcium signals.

Thus, for the first time we can manipulate cellular properties throughout a whole atrial muscle cell in order to deduce which conditions give rise to abnormalities.

The importance of the atrial kick

A human heart will beat more than one billion times during our lifetime. The main function of the heart is to pump blood. To generate the necessary force to propel blood through all the blood vessels, the heart beats with every contraction of its cells.

Most of these muscle cells surround the larger chambers of the heart, the ventricles. Under resting conditions, the ventricles are mainly responsible for contracting the heart. When blood needs to be pumped more quickly - for instance during exercise - the smaller chambers of the heart contribute to the contraction. This is known as the atrial kick. As we age or when something is wrong with our heart - such as atrial fibrillation - the atrial muscle cells start to deteriorate. As a result we lose the support of the atrial kick. Atrial fibrillation constitutes the most common form of cardiac arrhythmia irregular heart beat.

The role of calcium in keeping our heart fit

Several experimental studies have revealed that to trigger contraction in atrial muscle cells the calcium concentration follows an elaborate choreography which shows different concentration values in different parts of the cell. This is in contrast to ventricular cells where the calcium concentration is almost entirely uniform throughout the cell.

To fully understand atrial calcium dynamics we need to be able to monitor the atrial cell in its entirety. Unfortunately this is currently beyond even the best state-of-the-art experimental technology.

Moreover, experimental manipulations of cells usually interfere with more than one cellular control mechanism making it harder to tease apart the contributions of different pathways. Therefore, developing cutting edge models of atrial cellular behaviour is crucial to our understanding.

New mathematical model could save lives

Dr Thul said: "The strength of our model is that we can study the intracellular calcium concentration throughout the whole volume of the atrial muscle cell at the same time.

This allows for a detailed exploration of the spatio-temporal calcium patterns associated with both healthy and pathological conditions.

"Moreover, we can selectively activate, deactivate, over or under express cellular properties and see how they shape the calcium patterns. Hence, we can deduce which conditions give rise to abnormalities and might lead to diseases such as atrial fibrillation. It is important to remember that whatever pharmaceutical treatment is administered, it acts at the single cell level.

The response of an organ always results from the interaction of its cellular components. Looking ahead to treatments of atrial fibrillation and other cardiac pathologies, a fully three-dimensional model of an atrial cell offers an ideal testing ground for new drugs

- MNT

It's in the genes - when your left hand mimics what your right hand does

Further work carried out on mice suggests that this gene plays a part in motor network cross-over. Cross-over is a key factor in the transmission of brain signals, because it allows the right side of the brain to control the left side of the body and vice versa. This research has been published in The American Journal of Human Genetics.

Congenital mirror movement is a rare disease transmitted from one generation to another by dominant inheritance. The affected persons lose the ability to carry out different movements with separate hands: when one hand moves in a certain way, the other hand is "forced" to copy the same movement, even if the person does not wish to do so.

So people suffering from this disease are totally incapable of bimanual motor activities, such as piano playing for example. This phenomenon has been observed in children, but generally cleared up spontaneously before the age of 10, no doubt due to maturing of the motoneuron networks.

However, in people who are affected by the disorder, the illness starts in early childhood and remains unchanged throughout life.

In 2010, research scientists from Quebec analysed the genome from the members of a large Canadian family and discovered a gene responsible for the disease. Mutations had been detected in the DCC (Deleted in Colorectal Carcinoma) gene.

Discovery

Following this discovery, the team of researchers and doctors coordinated by Emmanuel Flamand-Roze began to search for mutations in this gene in several members of a French family who were also suffering from congenital mirror movements disease, but without success.

"The DCC gene was intact", explained Emmanuel Flamand-Roze. "We thought we were nearly there and instead we had to start searching for mutation in a different gene", he adds.

Using an approach that combines conventional genetic analysis and "whole exome" analysis (a new-generation genetic analysis technique that involves entirely sequencing the important part of the genome), scientists demonstrated that the RAD51 gene was responsible for congenital mirror movement disease in a large French family and went on to corroborate this result using the same techniques on a German family suffering from the same disorder.

"The RAD51 gene was already known to the scientific community as a potential catalyst for certain types of cancer and in problems of resistance to chemotherapy", explains Emmanuel Flamand-Roze. "So we wondered whether it had yet another function that could explain the motor symptoms of CMM disease".

In humans, the motor system is a cross-control system, which means that the left side of the brain controls the motor functions of the right side of the body and vice versa, with the cross-over taking place at the brainstem.

Expression

While studying the expression of the RAD51 protein during development of the motor system in mice, the research scientists discovered that this gene could be implanted into the cross-over of the motor network that links the brain to the spinal fluid at the brainstem.

This discovery opens up a whole new field of investigation into the development of the motor system and to achieving better understanding of the cerebral mechanisms that control bimanual motricity. It could also shed light on other motricity disorders related to fine movement organisation,such as dystonia or certain genetic neurodevelopmental diseases.

- medicalxpress