A lot more OET tests at lotsoftests.com...
Occupational English Test
READING SUB-TEST Part B - Text Booklet Practice test You must record your answers for Part B on the multiple-choice answer sheet using 2B pencil. Please print in BLOCK LETTERS
Candidate number
–
–
Family name
Other name(s)
City
Date of test
Candidate’s signature
YOU MUST NOT REMOVE OET MATERIAL FROM THE TEST ROOM.
The OET Centre GPO Box 372 Melbourne VIC 3001 Australia © OET Centre — Practice test
Telephone: +61 3 9652 0800 Facsimile: +61 3 9654 5329 www.occupationalenglishtest.org
ABN 84 434 201 642
READING PART B Instructions TIME LIMIT: 45 MINUTES
There are TWO reading texts in Part B. After each of the texts you will find a number of questions or unfinished statements about the text, each with four suggested answers or ways of finishing. You must choose the ONE which you think fits best. For each question, 1-20, indicate on your answer sheet the letter A, B, C or D against the number of the question. Answer ALL questions. Marks are NOT deducted for incorrect answers. NOTE: You must complete your Answer Sheet for Part B within the 45 minutes allowed for this part of the sub-test.
NOW TURN TO THE NEXT PAGE FOR TEXTS AND QUESTIONS
Reading Part B
Part B : Multiple Choice Questions Time Limit: 20~25 Minutes Alzheimer Disease Author: Margaret Gatz Source: Public Library of Open Science
Paragraph 1 Physicians now commonly advise older adults to engage in mentally stimulating activity as a way of reducing their risk of dementia. Indeed, the recommendation is often followed by the acknowledgment that evidence of benefit is still lacking, but “it can’t hurt.” What could possibly be the problem with older adults spending their time doing crossword puzzles and anagrams, completing puzzles, or testing their reaction time on a computer? In certain respects, there is no problem. Patients will probably improve at the targeted skills, and may feel good—particularly if the activity is both challenging and successfully completed. Paragraph 2 But can it hurt? Possibly. There are two ways that encouraging mental activity programs might do more harm than good. First, they can falsely raise expectations. Second, individuals who do develop dementia might be blamed for their condition. When heavy smokers get lung cancer, they are sometimes seen as having contributed to their own fates. People with Alzheimer disease might similarly be viewed as having brought it on themselves through failure to exercise their brains. Paragraph 3 There is some evidence to support the idea that mental exercise can improve one’s chances of escaping Alzheimer disease. Having more years of education has been shown to be related to a lower prevalence of Alzheimer disease. Typically, the risk of Alzheimer disease is two to four times higher in those who have fewer years of education, as compared to those who have more years of education. Other epidemiological studies, although with less consistency, have suggested that those who engage in more leisure activities have a lower prevalence and incidence of Alzheimer disease. Additionally, longitudinal studies have found that older adults without dementia who participate in more intellectually challenging daily activities show less decline over time on various tests of cognitive performance. Paragraph 4 However, both education and leisure activities are imperfect measures of mental exercise. For instance, leisure activities represent a combination of influences. Not only is there mental activation, but there may also be broader health effects, including stress reduction and improved vascular health— both of which may contribute to reducing dementia risk. It could also be that a third factor, such as intelligence, leads to greater levels of education and more engagement in cognitively stimulating activities, and independently, to lower risk of dementia. Research in Scotland, for example, showed that IQ test scores at age 11 were predictive of future dementia risk . This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Paragraph 5 The concept of cognitive reserve is often used to explain why education and mental stimulation are beneficial. The term cognitive reserve is sometimes taken to refer directly to brain size or to synaptic density in the cortex. At other times, cognitive reserve is defined as the ability to compensate for acquired brain pathology. Taken together, the evidence is very suggestive that having greater cognitive reserve is related to a reduced risk of Alzheimer disease. But the evidence that mental exercise can increase cognitive reserve and keep dementia at bay is weaker. In addition, people with greater cognitive reserve may choose mentally stimulating leisure activities and jobs, which makes is difficult to precisely determine whether mentally stimulating activities alone can reduce dementia risk. Paragraph 6 Cognitive training has demonstrable effects on performance, on views of self, and on brain function—but the results are very specific to the skills that are trained, and it is as yet entirely unknown whether there is any effect on when or whether an individual develops Alzheimer disease. Further, the types of skills taught by practicing mental puzzles may be less helpful in everyday life than more straightforward techniques, such as concentrating, or taking notes, or putting objects in the same place each time so that they won’t be lost. Paragraph 7 So far, there is little evidence that mental practice will help prevent the development of dementia. There is better evidence that good brain health is determined by multiple factors, that brain development early in life matters, and that genetic influences are of great importance in accounting for individual differences in cognitive reserve and in explaining who develops Alzheimer disease and who does not. At least half of the explanation for individual differences in susceptibility to Alzheimer disease is genetic, although the genes involved have not yet been completely discovered. The balance of the explanation lies in environmental influences and behavioral health practices, alone or in interaction with genetic factors. However, at this stage, there is no convincing evidence that memory practice and other cognitively stimulating activities are sufficient to prevent Alzheimer disease; it is not just a case of “use it or lose it.”
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Part B : Multiple Choice Questions 1. According to paragraph 1, which of the following statements matches the opinion of most doctors? a. Mentally stimulating activities are of little use b. The risk of dementia can be reduced by doing mentally stimulating activities c. The benefits of mentally stimulating activities are not yet proven d. Mentally stimulating activities do more harm than good 2. In paragraph 2, the author expresses the opinion that ……. a. Mentally stimulating activities may offer false hope b. Dementia sufferers often blame themselves for their condition c. Alzheimer’s disease may be caused lack of mental exercise d. Mentally stimulating activities do more harm than good 3. In paragraph 3, which of the following does not match the information on research into Alzheimer disease? a. People with less education have a higher risk of Alzheimer disease b. Cognitive performance can be enhanced by regularly doing activities which are mentally challenging c. Having more education reduces the risk of Alzheimer disease d. Regular involvement in leisure activities may reduce the risk of Alzheimer disease 4. According to paragraph 4, which of the following statements is false? a. The impact of education and leisure is difficult to measure b. Better vascular health and reduced stress can decrease the risk of dementia c. People with higher IQ scores may be less likely to suffer from dementia d. Cognitively stimulating activities reduce dementia risk 5. Which of the following is closest in meaning to the expression: keep dementia at bay? a. delay the onset of dementia b. cure dementia c. reduce the severity of dementia d. treat dementia 6. Which of the following phrases best summarises the main idea presented in paragraph 6? a. The effect cognitive training has on Alzheimer disease is limited b. Doing mental puzzles may not be as beneficial as concentrating in everyday life c. Cognitive training improves brain performance d. The effect cognitive training has on Alzheimer disease is indefinite
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
7. According to paragraph 7, which of the following is correct regarding the development of dementia? a. Genetic factors are the most significant b. Environmental factors interact with behavioural factors in determining susceptibility to Alzheimer disease c. Good brain health can reduce the risk of developing Alzheimer disease d. None of the above 8. Which of the following would be the best alternative title for the essay? a. New developments in Alzheimer research b. Benefits of education in fighting Alzheimer disease c. Doubts regarding mental exercise as a preventive measure for Alzheimer disease d. The importance of cognitive training in preventing early onset of Alzheimer disease
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Part B : Multiple Choice Questions
Time Limit: 20~25 Minutes
Infectious Diseases and Climatic Influences
Authors: Bernard Cazelles, Simon Hales Source: Public Library of Open Science
Paragraph 1 Complex dynamic relationships between humans, pathogens, and the environment lead to the emergence of new diseases and the re-‐emergence of old ones. Due to concern about the impact of increasing global climate variability and change, many recent studies have focused on relationships between infectious disease and climate. Paragraph 2 Climate can be an important determinant of vector-‐borne disease epidemics: geographic and seasonal patterns of infectious disease incidence are often, though not always, driven by climate factors. Mosquito-‐ borne diseases, such as malaria, dengue fever, and Ross River virus, typically show strong seasonal and geographic patterns, as do some intestine diseases. These patterns are unsurprising, given the influence of climate on pathogen replication, vector and disease reservoir populations, and human societies. In Sweden, a trend toward milder winters and early spring arrival may be implicated in an increased incidence of tick-‐borne encephalitis. The recent resurgence of malaria in the East African highlands may be explained by increasing temperatures in that region. However, as yet there are relatively few studies showing clear climatic influences on infectious diseases at interannual or longer timescales. Paragraph 3 The semi-‐regular El Niño climate cycle, centred on the Pacific Ocean, has an important influence on interannual climate patterns in many parts of the world. This makes El Niño an attractive, albeit imperfect, analogue for the effects of global climate change. In Peru, daily admissions for diarrhoea increased by more than 2-‐fold during an El Niño event, compared with expected trends based on the previous five years. There is evidence of a relationship between El Niño and the timing of cholera epidemics in Peru and Bangladesh; of ciguatera in the Pacific islands; of Ross River virus epidemics in Australia; and of dengue and malaria epidemics in several countries. The onset of meningococcal meningitis in Mali is associated with large-‐scale atmospheric circulation. Paragraph 4 These studies were performed mostly at country scale, reflecting the availability of data sources and, perhaps, the geographically local effects of El Niño on climate. In part because of this geographic “patchiness” of the epidemiological evidence, the identification of climatic factors in infectious disease dynamics, and the relative importance of the different factors, remains controversial. For example, it has been suggested that climate trends are unlikely to contribute to the timing of dengue epidemics in Thailand. However, recent work has shown a strong but transient association between dengue incidence and El Niño in This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Thailand. This association may possibly be caused by a “pacemaker-‐like” effect in which intrinsic disease dynamics interact with climate variations driven by El Niño to propagate travelling waves of infection. Paragraph 5 A new study on cutaneous leishmaniasis by Chaves and Pascual also provides fresh evidence of a relationship between climate and vector-‐borne disease. Chaves and Pascual use a range of mathematical tools to illustrate a clear relationship between climatic variables and the dynamics of cutaneous leishmaniasis, a skin infection transmitted by sandflies. In Costa Rica, cutaneous leishmaniasis displays three-‐year cycles that coincide with those of El Niño. Chaves and Pascual use this newly demonstrated association to enhance the forecasting ability of their models and to predict the epidemics of leishmaniasis up to one year ahead. Interestingly, El Niño was a better predictor of disease than temperature, possibly because this large-‐scale index integrates numerous environmental processes and so is a more biologically relevant measure than local temperature. As the authors note, the link between El Niño and epidemics of leishmaniasis might be explained by large-‐scale climate effects on population susceptibility. Susceptibility, in turn, may be related to lack of specific immunity or poor nutritional status, both of which are plausibly influenced by climate. Paragraph 6 Chaves and Pascual have identified a robust relationship between climate and disease, with changes over time in average incidence and in cyclic components. The dynamics of cutaneous leishmaniasis evolve coherently with climatic variables including temperature and El Niño indices, demonstrating a strong association between these variables, particularly after 1996. Long-‐term changes in climate, human demography, and social features of human populations have large effects on the dynamics of epidemics as underlined by the analyses of some large datasets on whooping cough and measles. Another illuminating example is the transient relationship between cholera prevalence and El Niño oscillations. In Bangladesh, early in the 20th century, cholera and El Niño appeared unrelated, yet a strong association emerged in 1980–2001. Transient relationships between climate and infectious disease may be caused by interactions between climate and intrinsic disease mechanisms such as temporary immunity. If population susceptibility is low, even large increases in transmission potential due to climate forcing will not result in a large epidemic. Paragraph 7 A deeper understanding of infectious disease dynamics is important in order to forecast, and perhaps forestall, the effects of dramatic global social and environmental changes. Conventional statistical methods may fail to reveal a relationship between climate and health when discontinuous associations are present. Because classical methods quantify average associations over the entire dataset, they may not be adequate to decipher long-‐term but discontinuous relationships between environmental exposures and human health. On the other hand, relationships between climate and disease could signal problems for This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
disease prediction. Unless all important effects are accounted for, dynamic forecast models may prove to have a limited shelf life. ! Part B : Multiple Choice Questions 1. According to paragraph 2, which of the following is true? a. The incidence of infectious diseases is rarely caused by climatic factors. b. Seasonal variations and geography always lead to increases in mosquito borne diseases. c. An increase in the rate of tick-borne encephalitis has been caused by milder winters and early arrival spring in Sweden. d. Malaria may have reappeared in East African highlands due to higher temperatures. 2. Which of the following would be the most appropriate heading for the paragraph 2? a. The link between global warming and disease epidemics . b. The strong relationship between climate and outbreaks of disease. c. The unexpected influence of climate on infectious diseases. d. The need for further research into climate change and infectious diseases. 3. Which of the following is closest in meaning to the expression relatively few? a. comparatively few b. several c. quite a few d. three 4. In paragraph 3, which of the following is not true? a. In Peru, the El Nino event led to increased rates of diarrhoea . b. El-Nino has a significant yearly effect on global climate patterns. c. Outbreaks of cholera in Bangladesh and Peru can be linked to El Nino. d. Meningococcal meningitis in Mali is influenced by weather patterns. 5. The main point the author wishes to raise in paragraph 4 is…………. a. Despite differing opinions, there is strong current evidence linking climate factors and infectious disease. b. There is insufficient data to determine how significant climatic factors are on infectious disease. c. The link between climate trends and disease epidemics is still inconclusive. d. There is no connection between climatic trends and dengue fever in Thailand.
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
6. According to paragraph 5 which of the following statements is correct? a. Outbreaks of cutaneous leishmaniasis in Costa Rica correspond with El Nino events. b. The mathematical tools used by Chaves and Pascual demonstrate the link between sandflies and cutaneous leishmaniasis. c. Research by Chaves and Pascual will allow for annual prediction of leishmaniasis outbreaks. d. El Nino is an accurate predictor disease due its complexity and biological relevance. 7. Which of the following is closest in meaning to the word plausibly? a. definitely b. possibly c. regularly d. occasionally 8. According to paragraph 6, which of the following statements is correct? a. The relationship between climate and disease is constant. b. Outbreaks of cholera appear to be unrelated to El Nino patterns. c. The dynamics of epidemics are affected by changes in population, society and weather. d. Large epidemics rarely occur due to climate changes. 9. Which of the following is closest in meaning to transient relationship? a. Strong relationship b. Long term relationship c. Close relationship d. Non-permanent relationship 10. In paragraph 7, which of the following statements is most correct? a. There may be weaknesses in orthodox statistical methods. b. The dynamics of infectious diseases in well understood. c. The data measuring long term relationships between human health and environmental exposure is inadequate. d. Relationships between climate and disease will make disease prediction difficult.
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Answer Key 1. c 2. a 3. b 4. d 5. a 6. d 7.a 8. c Question 1 a) Incorrect: No, they believe it may help b) Incorrect: This is their advice, but they acknowledge there is no evidence c) Correct: See highlight d) Incorrect: No, (this is the author’s opinion in paragraph 2) Question 2 a) Correct: synonym: (may offer false hope= can falsely raise expectations) b) Incorrect: Not mentioned c) Incorrect: No, some people may believe this, but not the author d) Incorrect: No, they might i.e it is possible Question 3 a) Incorrect: Matches b) Correct: Does not match: will not enhance, just stop the decline c) Incorrect: Matches d) Correct: Matches Question 4 a) Incorrect: True b) Incorrect: True c) Incorrect : True d) Correct: False: could reduce, not reduce…(degrees of certainty) Question 5 a) Correct b) Incorrect c) Incorrect d) Incorrect Question 6 a) Incorrect: Not mentioned b) Incorrect: True: but a detail c) Incorrect: True, but not the main idea d) Correct: synonym: unclear=unknown Question 7 a) Correct: see highlight b) incorrect: c) Incorrect: could be true but not mentioned d) Incorrect: Question 8 a) Incorrect: no new developments mentioned b) Incorrect: not the main focus c) Correct: Best summary d) Incorrect: opposite is true
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Alzheimer Disease
Author: Margaret Gatz Source: Public Library of Open Science
Paragraph 1 Physicians now commonly advise older adults to engage in mentally stimulating activity as a way of reducing their risk of dementia. Indeed, (1)the recommendation is often followed by the acknowledgment that evidence of benefit is still lacking, but “it can’t hurt.” What could possibly be the problem with older adults spending their time doing crossword puzzles and anagrams, completing puzzles, or testing their reaction time on a computer? In certain respects, there is no problem. Patients will probably improve at the targeted skills, and may feel good—particularly if the activity is both challenging and successfully completed. Paragraph 2 But can it hurt? Possibly. There are two ways that encouraging mental activity programs might do more harm than good. First, (2) they can falsely raise expectations. Second, individuals who do develop dementia might be blamed for their condition. When heavy smokers get lung cancer, they are sometimes seen as having contributed to their own fates. People with Alzheimer disease might similarly be viewed as having brought it on themselves through failure to exercise their brains. Paragraph 3 There is some evidence to support the idea that mental exercise can improve one’s chances of escaping Alzheimer disease. Having more years of education has been shown to be related to a lower prevalence of Alzheimer disease. Typically, the risk of Alzheimer disease is two to four times higher in those who have fewer years of education, as compared to those who have more years of education. Other epidemiological studies, although with less consistency, have suggested that those who engage in more leisure activities have a lower prevalence and incidence of Alzheimer disease. Additionally, (3)longitudinal studies have found that older adults without dementia who participate in more intellectually challenging daily activities show less decline over time on various tests of cognitive performance. Paragraph 4 However, both education and leisure activities are imperfect measures of mental exercise. For instance, leisure activities represent a combination of influences. Not only is there mental activation, but there may also be broader health effects, including stress reduction and improved vascular health— both of which may contribute to reducing dementia risk. (4)It could also be that a third factor, such as intelligence, leads to greater levels of education and more engagement in cognitively stimulating activities, and independently, to lower risk of dementia. Research in Scotland, for example, showed that IQ test scores at age 11 were predictive of future dementia risk . This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Paragraph 5 The concept of cognitive reserve is often used to explain why education and mental stimulation are beneficial. The term cognitive reserve is sometimes taken to refer directly to brain size or to synaptic density in the cortex. At other times, cognitive reserve is defined as the ability to compensate for acquired brain pathology. Taken together, the evidence is very suggestive that having greater cognitive reserve is related to a reduced risk of Alzheimer disease. But the evidence that mental exercise can increase cognitive reserve and (5)keep dementia at bay is weaker. In addition, people with greater cognitive reserve may choose mentally stimulating leisure activities and jobs, which makes is difficult to precisely determine whether mentally stimulating activities alone can reduce dementia risk. Paragraph 6 Cognitive training has demonstrable effects on performance, on views of self, and on brain function—but the results are very specific to the skills that are trained, and (6) it is as yet entirely unknown whether there is any effect on when or whether an individual develops Alzheimer disease. Further, the types of skills taught by practicing mental puzzles may be less helpful in everyday life than more straightforward techniques, such as concentrating, or taking notes, or putting objects in the same place each time so that they won’t be lost. Paragraph 7 So far, there is little evidence that mental practice will help prevent the development of dementia. There is better evidence that good brain health is determined by multiple factors, that brain development early in life matters, and that genetic influences are of great importance in accounting for individual differences in cognitive reserve and in explaining who develops Alzheimer disease and who does not. (7)At least half of the explanation for individual differences in susceptibility to Alzheimer disease is genetic, although the genes involved have not yet been completely discovered. The balance of the explanation lies in environmental influences and behavioral health practices, alone or in interaction with genetic factors. However, at this stage, there is no convincing evidence that memory practice and other cognitively stimulating activities are sufficient to prevent Alzheimer disease; it is not just a case of “use it or lose it.”
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Answer Key 1. d 2. b 3. a 4. b 5. a 6. a 7.b 8. c 9. d 10. a Question 1 a) Incorrect: Not rarely, often b) Incorrect: Not mentioned c) Incorrect: may be implicated, not has lead d) Correct: (synonym resurgence=reappearance) key word may Question 2 a) Incorrect: global warming not mentioned b) Correct: (synonym disease epidemics=outbreaks of disease) important determinant=strong relationship c) Incorrect: Opposite is true d) Incorrect: True fact but a detail not the main idea Question 3 a) Correct b) Incorrect c) Incorrect d) Incorrect Question 4 a) Incorrect: True: diarrhoea increased by more than 2-‐fold during an El Niño event b) Correct: Not true as the effects are semi-‐regular/interannual i.e between years not yearly c) Incorrect: True: There is evidence of a relationship between El Niño and the timing of cholera epidemics in Peru and Bangladesh d) Incorrect: True: The onset of meningococcal meningitis in Mali is associated with large-‐scale atmospheric circulation Question 5 a) Correct: The author is trying demonstrate that there is a clear link between climate factors and infectious disease. Key words However & synonym: current=recent b) Incorrect: While this may be true, it s not the authors main point c) Incorrect : as in B d) Incorrect Question 6 a) Correct: (synonym coincide=correspond) b) Incorrect: incorrect meaning c) Incorrect: not annually, one year ahead d) Incorrect: not given, it is a better predictor than temperature Question 7 a) Incorrect b) Correct c) Incorrect d) Incorrect Question 8 a) Incorrect: not constant, changes over time b) Incorrect: This was a past opinion, not now c) Correct: similar meaning d) Incorrect: Incomplete information Question 9 a) Incorrect b) Incorrect c) Incorrect d) Correct Question 10 a) Correct: (synonyms conventional=orthodox & may be short comings=may fail) b) Incorrect: no, deeper understanding is important c) Incorrect: Not the data, the methods d) Incorrect: Degrees of certainty: Could not will This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Infectious Diseases and Climatic Influences Bernard Cazelles, Simon Hales Paragraph 1 Complex dynamic relationships between humans, pathogens, and the environment lead to the emergence of new diseases and the re-emergence of old ones. Due to concern about the impact of increasing global climate variability and change, many recent studies have focused on relationships between infectious disease and climate. Paragraph 2 (2)Climate can be an important determinant of vector-borne disease epidemics: geographic and seasonal patterns of infectious disease incidence are often, though not always, driven by climate factors. Mosquito- borne diseases, such as malaria, dengue fever, and Ross River virus, typically show strong seasonal and geographic patterns, as do some intestine diseases. These patterns are unsurprising, given the influence of climate on pathogen replication, vector and disease reservoir populations, and human societies. In Sweden, a trend toward milder winters and early spring arrival may be implicated in an increased incidence of tick-borne encephalitis. (1)The recent resurgence of malaria in the East African highlands may be partly explained by increasing temperatures in that region. However, as yet there are (3) relatively few studies showing clear climatic influences on infectious diseases at interannual or longer timescales. Paragraph 3 The (4) semi-regular El Niño climate cycle, centred on the Pacific Ocean, has an important influence on interannual climate patterns in many parts of the world. This makes El Niño an attractive, albeit imperfect, analogue for the effects of global climate change. In Peru, daily admissions for diarrhoea increased by more than 2-fold during an El Niño event, compared with expected trends based on the previous five years. There is evidence of a relationship between El Niño and the timing of cholera epidemics in Peru and Bangladesh; of ciguatera in the Pacific islands; of Ross River virus epidemics in Australia; and of dengue and malaria epidemics in several countries. The onset of meningococcal meningitis in Mali is associated with largescale atmospheric circulation. Paragraph 4 These studies were performed mostly at country scale, reflecting the availability of data sources and, perhaps, the geographically local effects of El Niño on climate. In part because of this geographic “patchiness” of the epidemiological evidence, the identification of climatic factors in infectious disease dynamics, and the relative importance of the different factors, remains controversial. For example, it has been suggested that climate trends are unlikely to contribute to the timing of dengue epidemics in Thailand. (5)However, recent work has shown a strong but transient association between dengue incidence and El Niño in Thailand. This association may possibly be caused by a “pacemaker-like” effect in which intrinsic disease dynamics interact with climate variations driven by El Niño to propagate travelling waves of infection.
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
Reading Part B
Paragraph 5 A new study on cutaneous leishmaniasis by Chaves and Pascual also provides fresh evidence of a relationship between climate and vector-borne disease. Chaves and Pascual use a range of mathematical tools to illustrate a clear relationship between climatic variables and the dynamics of cutaneous leishmaniasis, a skin infection transmitted by sandflies. (6)In Costa Rica, cutaneous leishmaniasis displays threeyear cycles that coincide with those of El Niño. Chaves and Pascual use this newly demonstrated association to enhance the forecasting ability of their models and to predict the epidemics of leishmaniasis up to one year ahead. Interestingly, El Niño was a better predictor of disease than temperature, possibly because this large-scale index integrates numerous environmental processes and so is a more biologically relevant measure than local temperature. As the authors note, the link between El Niño and epidemics of leishmaniasis might be explained by large-scale climate effects on population susceptibility. Susceptibility, in turn, may be related to lack of specific immunity or poor nutritional status, both of which are plausibly influenced by climate. Paragraph 6 Chaves and Pascual have identified a robust relationship between climate and disease, with changes over time in average incidence and in cyclic components. The dynamics of cutaneous leishmaniasis evolve coherently with climatic variables including temperature and El Niño indices, demonstrating a strong association between these variables, particularly after 1996. (8)Long-term changes in climate, human demography, and social features of human populations have large effects on the dynamics of epidemics as underlined by the analyses of some large datasets on whooping cough and measles. Another illuminating example is the transient relationship between cholera prevalence and El Niño oscillations. In Bangladesh, early in the 20th century, cholera and El Niño appeared unrelated, yet a strong association emerged in 1980–2001. Transient relationships between climate and infectious disease may be caused by interactions between climate and intrinsic disease mechanisms such as temporary immunity. If population susceptibility is low, even large increases in transmission potential due to climate forcing will not result in a large epidemic. Paragraph 7 A deeper understanding of infectious disease dynamics is important in order to forecast, and perhaps forestall, the effects of dramatic global social and environmental changes. (10) Conventional statistical methods may fail to reveal a relationship between climate and health when discontinuous associations are present. Because classical methods quantify average associations over the entire dataset, they may not be adequate to decipher long-term but discontinuous relationships between environmental exposures and human health. On the other hand, relationships between climate and disease could signal problems for disease prediction. Unless all important effects are accounted for, dynamic forecast models may prove to have a limited shelf life. !
This resource was developed by OET Online and is subject to copyright © Website: http://oetonline.com.au Email:
[email protected]
