Communicable diseases in the Gulf: the case of tuberculosis.
Yeboah, David Achanfuo
INTRODUCTION
THROUGHOUT THE WORLD, COMMUNICABLE diseases are assuming increasing
importance both in terms of morbidity (disease) and mortality (deaths).
Communicable diseases are the principal causes of deaths in many
countries around the world. Communicable diseases incapacitate millions
of people every year and, while much of this incapacitation is usually
temporary, productivity is, by and large, adversely affected. The effect
of communicable diseases on productivity is often measured in terms of
years of life lost as a result of the incidence and prevalence of
communicable diseases The Arabian Gulf is one geographical region where
anecdotal evidence suggests that not only do communicable diseases
thrive, but that they substantially impact on productivity.
According to the World Health Organization (2003), all the Gulf
Cooperating Countries (GCC) incurred productivity losses as a result of
communicable diseases. For example, the Organization reported that, in
2002, the Years of Life lost due to communicable diseases were 10, 18,
24, 16, 22 and 12 for Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the
United Arab Emirates (UAE) respectively. Oman recorded the highest Years
of Life lost, while the UAE recorded the lowest. The prevalence of
communicable diseases and their impact in the Gulf presupposes a need to
examine some of the leading communicable diseases in detail, hence the
rationale behind this study. Besides, the Region is under-represented in
the literature on communicable diseases. Two of the most prominent
communicable diseases in the world are Tuberculosis and HIV/AIDS. These
diseases are also present in the Gulf and, in this first article in the
series of investigations into communicable diseases in the Gulf, the
focus is on tuberculosis.
PURPOSE
The purpose of this article is to examine the incidence, prevalence
and the risk of acquiring Tuberculosis in the Gulf Region, focusing
particularly on the Gulf Cooperating Countries (GCC as they are usually
called). The article also examines detection and treatment rates as well
as mortality from Tuberculosis in those countries. The objective is to
throw more light on the subject, provide useful insights, and increase
understanding of the epidemiology of the disease in the said countries.
While the disease is rife in the Region affecting both locals and
Expatriates, studies on the diseases in the Gulf are conspicuously
missing in the literature.
SOURCES OF DATA AND METHODOLOGIES
The data used in this study have come from the statistical sources
of the World Health Organization. The methodologies involve an
epidemiological analysis of data and the computation of epidemiological
measures such as incidence and prevalence rates, risk indicators,
mortality, detection and treatment rates. These computations and
analysis increase the existing knowledge and understanding of
Tuberculosis (TB) in the Region.
FINDINGS
The findings of the study are summarized under the broad headings
of population, morbidity, mortality, detection and treatment. The
population of any country has the potential to acquire any diseases
prevailing in the country. The population is also the ultimate
beneficiary of any program including treatment or therapeutic programs
available in that country (Yeboah, 1998). Thus the study examines the
population of the GCC Members in terms of their population sizes. The
findings on morbidity concentrate on incidence, prevalence, and risk
associated with Tuberculosis, while the mortality findings look at
mortality from Tuberculosis for the population which is not positive to
HIV/AIDS. The epidemiological analyses are followed by a discussion of
levels of detection and treatment.
POPULATION
Member countries of the GCC have a total population of 35.247
million. Table 1 shows the total population and annual population growth
rates of the Gulf Cooperating Countries. Saudi Arabia recorded the
largest population size of 24.2 million in 2006, followed by the United
Arab Emirates (UAE) 4.2 million, Kuwait 2.8 million, Oman 2.5 million,
Qatar 0.8 million and Bahrain 0.7 million.
MORBIDITY
With regards to morbidity analysis, the study examined three
essential areas, namely incidence, prevalence and the risk of getting
infected with Tuberculosis (TB) in the GCC.
INCIDENCE RATES
Table 2 shows the Incidence Rates of TB in the GCC from 1990 to
2006. Incidence Rates refer to new cases of TB and indicates the level
at which residents are being infected with the diseases. In 1990 Bahrain
recorded the highest Incidence Rate of 78 per 100 000 population. This
means that, out of every 100 000 residents of Bahrain in 1990 76 became
infected with the disease for the 1st time (new cases).The 2nd highest
Incidence Rate was recorded by Qatar (60 per 100 000 population),
followed by Kuwait (45), Saudi Arabia (43), UAE (30), AND Oman (26) per
100 000 population. Oman, therefore, recorded the lowest Incidence Rate
of TB in the GCC in 1990. The Mean Incidence Rate for the GCC as a whole
in 1990 was 46.7 per 100 000 population.
A new pattern emerged in the Incidence Rates in 2000. Qatar
recorded the highest Incidence Rate of 66 per 100 000 population,
overtaking Bahrain. The 2nd highest Incidence Rate was recorded by
Bahrain and Saudi (47 per 100 000 population), followed by Kuwait, UAE
and Oman, 28.0, 18.0 and 12.0 per 100 000 population respectively. Qatar
continued to record the highest Incidence Rate in 2006 followed in
descending order by Saudi Arabia, Bahrain, Kuwait, the UAE and Oman
(table 2). The Qatar recorded the highest Incidence Rates in both 2000
and 2006 (having been the 2nd highest in 1990), and Oman continued to
record the lowest Incidence Rates in 2000 and 2006, having recorded the
lowest in 1990 as well. It must be mentioned that Qatar actually
recorded an increase in Incidence Rates between 1990 and 2000, from 60
per 100 000 population in 1990 to 66.0 per 100 000 population in 2000.
While Saudi Arabia also recorded an increase in Incidence Rates, the
increase from 43 to 47 per 100 000 population was comparatively smaller.
It is significant to note that, with the exception of Qatar where
the rates remained stagnant, (0.0) and Saudi Arabia where the Incidence
Rate increased slightly by 2.3%, most Member countries of the GCC
recorded large declines in Incidence Rates of TB. The highest decline in
Incidence Rates occurred in Kuwait (50.0 %), followed by the UAE and
Kuwait (46.7% each) and Bahrain (46.1%). During the same 16 year period
from 1990 to 2006, the Mean Incidence Rate for the GCC as a whole
declined by 29.3%., a positive indication of the successful efforts to
control the disease in the GCC.
PREVALENCE RATES
The difference between Incidence Rates and Prevalence Rates is that
Incidence Rates refer to new cases or new infections only while
Prevalence Rates cover all cases or the total number of infections (both
new and existing cases). Prevalence Rates are usually higher than
Incidence Rates basically because, by definition, Prevalence Rates
include Incidence Rates. Prevalence Rates of TB in the GCC during the
period 1990 to 2006 are presented in Table 3.
A glance at Table 3 reveals that the patterns and trends in
Incidence Rates recorded during the 1990-2006 period were similar to the
patterns and trends in Prevalence Rates in the GCC during the same
period. Bahrain recorded the highest Prevalence Rates in 1990 (120 per
100,000 population) followed by Kuwait (89), Qatar (71), and the UAE
(47) per 100 000 population. Oman recorded the lowest Prevalence Rate in
1990, 40 per 100,000 population The Mean Prevalence Rate for the GCC as
whole in 1990 was 72.5 per 100,000 population.
As the case with Incidence Rates, Qatar leaped to the front and
recorded the highest Prevalence Rate in 2000, the only exception in the
pattern is that Saudi Arabia also overtook Bahrain and recorded the 2nd
highest Prevalence Rate In that year. Qatar and Saudi Arabia recorded
Prevalence Rates of 78 and 67 per 100,000 population respectively
compared with 57 per 100,000 population for Bahrain. Consistent with the
Incidence Rates, Oman recorded the lowest Prevalence in 2000, just 13
per 100,000 population (Table 3). All the study countries recorded
declining Prevalence Rates during the1990-2000 decade, except Qatar
which recorded an increase of about 9.9 %. In epidemiological terms, an
increase of almost 10 % is significant and worthy of mention, especially
during a period the rates for surrounding or neighboring countries were
on the decline. The Mean Prevalence Rate of TB in 2000 for the GCC was
45.7 per 100,000 population, a decline of 37 % during the 1990-2000
decade.
The prevalence of TB in the GCC declined generally during the 16
year period from 1990 to 2006. All the study countries recorded
declining rates during the period, except Qatar which again recorded a
small increase of 2.8% in the TB Prevalence Rate. Saudi Arabia recorded
a slight decline of 8.8%, while Kuwait recorded the highest decline of a
massive 71.9 %, followed by Oman (65.0%), Bahrain (62.5%) and the UAE
(48.9%). The mean Prevalence Rate for the GCC as a whole declined
steadily from 72.5 per 100,000 population in 1990 to 45.7 per 100,000
population in 2000 and 40.5 per 100,000 population in 2006, a decline of
over 40% between 1990 and 2006. Prevalence Rates are very useful
epidemiological tools for measuring the burden of disease, with
implications for resource allocation and policy and program development.
(See also Rothman, 2002).
RISK
Risk refers to the probability or chance of being infected with TB.
The logical question is "what is the risk of getting TB if you are
a resident of one of the GCC?" Absolute Risks and Odds Ratio are
used in this article to investigate the risk of becoming sick with TB.
Absolute Risk is the risk to the whole population of each country (see
also Moon et al., 2000). In empirical terms, the Absolute Risk is
usually equal to the Incidence Rate. Odds simply are the chances that a
resident of the GCC may become infected with TB, measured by a ratio of
the probability of becoming sick with TB to the probability of surviving
the disease (i.e. not catching TB).
ABSOLUTE RISKS
Absolute Risk or the probability of becoming sick with TB is
indicated in table 4. It is evident that Absolute Risk was generally low
for the GCC in 2006, with Oman (.0001) and the UAE (.00016) recording
the lowest risks. With an Absolute Risk of .0002, Kuwait also recorded a
very low risk. Qatar (.0006), Saudi Arabia (.0004) and Bahrain (.0004)
recorded the highest Absolute Risk in the GCC. These low Absolute Risks
mean that, with regards to the whole population of each country, the
risk of becoming ill with TB is very low.
ODDS RATIO
AS shown in Table 4, the odds of getting TB in the GCC is very low
with Oman, Kuwait and the UAE recording comparatively lower Odds Ratio.
While the Odds Ratio was still very low in the other countries, Qatar
(0.0006), Bahrain (0.0004) and Saudi Arabia (0.0004) recorded higher
Odds Ratio in 2006. In epidemiology, when the number of new cases of the
disease is small, the Absolute Risk is low and the Odds Ratio tends to
equate the Absolute Risks. This is especially true of rare diseases
which tend to record small incidence levels (see, for example, Moon et
al., 2000).
MORTALITY
Mortality or deaths due to TB are shown in table 5 Deaths due to TB
in the HIV-negative population is used in this analysis because TB has
become part and parcel of HIV patients and many HIV-positive patients
are acquiring and dying from TB (see, for example, Population Council,
2005). Again, the rates are low, with Bahrain recording the highest
mortality rate of 9 deaths per 100 000 population in 1990, followed by
Qatar (6 per 100 000 population) and Saudi Arabia and Kuwait (5 per 100
000 population each). Consistent with the lowest risk found in the UAE
and Oman, the two countries recorded the lowest TB caused mortality in
1990, 3 and 2 deaths per 100 000 population respectively. Needless to
say that most TB positive foreigners are deported and, thereby, reducing
potential deaths.
With the exception of Qatar and Saudi Arabia which recorded minor
increases in mortality rates, all the other countries witnessed
declining mortality due to TB in 2000. In Qatar the rate increased from
6 to 7 per 100 000 population while in Saudi Arabia, the increase was
from 5 to 6 per 100 000 population during the 1990-3000 period. Kuwait
recorded the highest decline (albeit it is still small) from 5 in 1990
to 3 per 100 000 population in 2000, followed by Oman (from2 to 1 per
100 000 population) and the UAE (from3 to 2 per 100 000 population)
during the same period.
In 2006, further declines occurred in most of the countries. In
Bahrain mortality from TB declined from 5 per 100,000 population to 4
per 100 000 population between 2000 and 2006. Kuwait recorded a decline
from 3 to 2, and Saudi Arabia from 6 to 5 per 100 000 population during
the 6 year period from 2000 to 2006. There was no change in mortality
rates from TB in the UAE, Qatar and Oman during the 2000-2006 period
(table 5). Improvements in mortality are best assessed in the % change
from 1990 to 2006. Kuwait experienced the highest decline in mortality
of 60.0%m a very substantial decline. Bahrain recorded the next highest
decline in mortality (55.6%), followed by Oman (50.0% and the UAE
(33.3%). Saudi Arabia experienced no change in TB caused mortality in
the HIV-negative population while Qatar recorded an increase in
mortality of almost 17.0%.
TB DETECTION
To ensure continuous and sustained decline in mortality due to TB
it is crucial that infections are detected as quickly as they occur to
reduce spreading and enhance treatment. The proportion of TB cases
detected in the GCC for 2000 and 2006 are shown in table 6, indicating
wide variations in the degree or extent of detection among the 6
countries constituting the GCC. In 2000, only 17% of TB cases were
detected in Bahrain, the lowest detection level in the GCC in that year.
Kuwait recorded the highest detection proportion (65 %) followed by
Saudi Arabia (36%), Qatar (29%), and the UAE (27 %). There was no
reliable data for Oman. By 2006, changes in the proportion of TB cases
detected emerged, with the UAE recording the lowest detection percentage
in the GCC (only 17%). Kuwait continued to witness the highest detection
level of 95%, clearly very outstanding compared with the other countries
(table 5).The proportion of cases detected in Bahrain jumped
dramatically from 17% in 2000 to a massive 72% in 2006, the 2nd highest
in that year. Qatar and Saudi Arabia detected 52% and 40% of the TB
cases respectively in 2006.
According to Table 6, Bahrain recorded a massive 323.5% increase in
TB detection between 2000 and 2006. Given that TB cases cannot be
treated unless and until they are detected, this increase in Bahrain is
a very positive, useful and healthy development. The 2nd highest
increase in the level of TB detection was recorded in Qatar (79.3%),
followed by Kuwait 46.2% and Saudi Arabia (14.3%). The detection level
declined in the UAE by 37.0% Sight should not be lost of the fact that
as recent as 2006, Kuwait detected 95% of all TB cases, one of the
highest levels of detection in the world.
TB TREATMENT
Throughout the world, it is often the practice to develop and
implement curative therapy to control TB cases. The proportion of
detected TB cases successfully treated in the GCC is found in Table 7.
In 2000, Oman successfully treated 93% of all TB cases, the highest in
the GCC in that year. Oman was followed by the UAE (74%) , Bahrain, and
Saudi Arabia (73% each) and Kuwait (69%). The lowest TB treatment
success percentage was recorded in Qatar (66%).
In 2006, most of the countries recorded declining TB treatment
success levels, but Bahrain recorded the highest TB treatment success
percentage of 93, followed by Oman (90%), Qatar (83%), and the UAE
(73%). Apart from Bahrain and Qatar which recorded increases in TB
treatment success levels, all the other countries recorded lower TB
treatment success levels in 2006 that they did in 2000 (table 7). Not
only did Bahrain record the highest TB treatment success percentage in
2006, the country also recorded the largest increase in treatment
success between 2000 and 2006 (an increase of 27.4%). Qatar was closely
behind with an increase of 25.8%. Saudi Arabia recorded the largest
decline in TB treatment success of -11%, followed by Kuwait (-8.6%),
Oman (-3.2%) and the UAE (-1.4%).
CONCLUSION
Contrary to anecdotal evidence, the incidence and prevalence Rates
of TB were found to be relatively low. The empirical data analysis in
this study leads to the conclusion that the risk of acquiring TB as a
resident of the GCC is very low despite anecdotal evidence suggesting
otherwise. The steadily declining incidence and prevalence rates support
the conclusion that preventive and curative measures put in place by GCC
Governments and relevant government and non government agencies might be
working effectively. After all, as shown in Table 7, the proportion of
TB cases which were successfully treated were relatively high in many
countries during the study period, while the detection of TB also
increased generally in the GCC. Three of the countries recorded
increases in treatment rates between 2000 and 2006. The closeness of the
Odds Ratio to the Absolute Risk means that the number of new cases is
small and confirms further the conclusion that the risk of catching TB
is very low.
Nonetheless, it is important to continue with the policies and
programs which individually and severally have worked to result in these
low incidence, prevalence and risks, to avoid retrogressing to the high
incidence and prevalence levels recorded decades ago. Policies such as
quick isolation of TB sufferers must be continued unabated, and the
humane policy of treating infected foreigners before they are deported
is worthy of emulation and should be continued.
REFERENCES
Moon, G., and M. Gould (2000): Epidemiology: An Introduction.
Buckingham, Open University Press.
Population Council (2005): Different models of delivering
antiretroviral therapy and integration with TB services in South Africa.
New York, Population Council Horizon Project.
Rothman, K. J. (2002): Epidemiology: An introduction. Oxford,
Oxford University Press.
World Health Organization: WHO Statistical Information System
(WHOSIS). www.who.org
Yeboah, D. A. (1998): Basic demography. London, Minerva Press.
David Achanfuo Yeboah teaches in the Health Sciences Program, Zayed
University, Abu Dhabi, United Arab Emirates.
Table 1: Population size and annual population
growth rates, GCC 2006 (000s)
Country Population
Bahrain 731
Kuwait 2 770
Oman 2 546
Qatar 871
Saudi Arabia 24 175
UAE 4 248
Total 35 247
Source: World Health Organization (WHO)
Table 2: Incidence Rates of TB, GCC, 1990-2006
(per 100 000 population)
Change
Country 1990 2000 2006 1990-2006
Bahrain 76.0 47.0 41.0 46.1
Kuwait 45.0 28.0 24.0 46.7
Oman 26.0 12.0 13.0 50.0
Qatar 60.0 66.0 60.0 00.0
Saudi Arabia 43.0 47.0 44.0 -2.3
UAE 30.0 18.0 16.0 46.7
Mean 46.7 36.3 33.0 29.3
Source: Computed from WHO data
Table 3: Prevalence Rates of TB, GCC, 1990-2006
(per 100 000 population)
% Change
Country 1990 2000 2006 1990-2006
Bahrain 120.0 57.0 45.0 62.5
Kuwait 89.0 32.0 25.0 71.9
Oman 40.0 13.0 14.0 65.0
Qatar 71.0 78.0 73.0 -2.8
Saudi Arabia 68.0 67.0 62.0 8.8
UAE 47.0 27.0 24.0 48.9
Mean 72.5 45.7 40.5 44.1
Source: Computed from WHO data
Table 4: Absolute Risk and Odds Ratio, GCC, 2006
Absolute Probability Odds Odds
Country Risk of Surviving Ratio
Bahrain .0004 .9996 .0004/1-.0004 0.0004
Kuwait .0002 .9998 .0002/1-.0002 0.0002
Oman .0001 .9999 .0001/1-.9999 0.0001
Qatar .0006 .9994 .0005/1-.0006 0.0006
Saudi Arabia .0004 .9996 .0004/1-.00041 0.0004
UAE .0002 * .9998 .0002/.1-.0002 0.0002 *
Source: Computed from WHO data
* Rounded from the lower figure of .00016
Table 5: Mortality due to TB among HIV Negative
Population, GCC, 1990-2006 (per 100 000 population)
% Change
Country 1990 2000 2006 1990-2006
Bahrain 9 5 4 55.6
Kuwait 5 3 2 60.0
Oman 2 1 1 50.0
Qatar 6 7 7 -16.7
Saudi Arabia 5 6 5 0.0
UAE 3 2 2 33.3
Source: Computed from WHO data
Table 6: TB Detection, GCC, 2000-2006 (%)
% Change
Country 2000 2006 2000-2006
Bahrain 17 72 323.5
Kuwait 65 95 46.2
Oman -- -- --
Qatar 29 52 79.3
Saudi Arabia 35 40 14.3
UAE 27 17 -37.0
Source: Computed from WHO data
Table 7: TB Treatment Success, GCC,
2000-2006 (%)
% Change
Country 2000 2006 2000-2006
Bahrain 73 93 27.4
Kuwait 69 63 -8.6
Oman 93 90 -3.2
Qatar 66 83 25.8
Saudi Arabia 73 65 11.0
UAE 74 73 -1.4
Source: Computed from WHO data
