Various research works by scientists and medical experts have suggested that malaria, and particularly repeated episodes, could be responsible for hypertension and other cardiovascular diseases.
A recent report by the Lancet Global Health Journal, a leading journal for health issues, appraised about 10 research works of various experts which link malaria as an infectious disease to elevated blood pressure and other cardiovascular diseases (CVD).
The report is titled: “Increasing Blood Pressure: Could Malaria have a Role?”
The new findings constitute a new development in the field of medicine, especially on the causes of major diseases such as hypertension and CVDs.
The researches reviewed include one by Anjana RM, Unnikrishnan R, Deepa M, et al. titled: “Metabolic non-communicable disease health report of India: the ICMR-INDIAB national cross-sectional study (ICMR-INDIAB-17);” “Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants” by NCD Risk Factor Collaboration (NCD-RisC); “Prevalence of cardiovascular complications in malaria: a systematic review and Elevated Blood Pressure among Adolescents in Sub-Saharan Africa: A Systematic Review and Meta-Analysis,” is jointly written by Alexander Chen, Laura Waite, et al.
This study reported that more people from sub-Saharan Africa aged between 20 years and 60 years are affected by end-organ damage due to underlying hypertension than people in high-income countries.
Also, the Lancet Global Health Journal reports that one in 10 adolescents in sub-Saharan Africa has hypertension, and in India, one in three adults. It noted that between 2009 and 2019, a 100 per cent increase in the number of individuals with hypertension was reported globally.
This increase, according to the report, has been attributed to an increased prevalence of hypertension in low-income and middle-income countries.
“There’s a need to improve the rapid detection, formal diagnosis, and appropriate management of hypertension across the entire lifespan. A better understanding of the natural history of hypertension and end-organ damage is needed among people aged 20–40 years in sub-Saharan Africa,” it said.
At a regional level, research has shown the predominance of cardiovascular diseases in poor and middle-income countries.
In Nigeria, the most populated country in sub-Saharan Africa, there has been a concerning rise in cardiovascular disease prevalence in recent years, with a 150 per cent increase reported in some studies.
The CVD is considered the highest burden of non-communicable diseases.
According to this report, CVDs account for nearly 10 per cent of deaths and 3.8 per cent of disability-adjusted life in Nigeria, surpassing deaths caused by common infectious diseases.
Malaria in Africa, India
Each year, there are at least 200 million cases of malaria, resulting in almost half a million deaths annually and more than 90 per cent of all malaria deaths occur in Sub-Saharan Africa.
According to the WHO 2022 World Malaria Report, there were 249 million cases of malaria in 2022 compared to 244 million cases in 2021.
WHO added that deaths caused by malaria rose to 608,000 in 2022 compared to 610,000 in 2021.
Four African countries – Nigeria, the Democratic Republic of the Congo, Uganda and Mozambique reportedly accounted for more than half of all malaria deaths worldwide, contributing 26.8, 12.3, 5.1 and 4.2 per cent respectively.
The disease is responsible for 11 per cent of maternal deaths and 25 per cent of deaths in infants.
Meanwhile, India carries 1.7 per cent of the global malaria burden and 85.2 per cent of the burden in Southeast Asia. The country also carries 1.2 per cent of global malaria deaths.
New findings
According to the new report, people in sub-Saharan Africa and India are more likely to experience cardiovascular diseases due to malaria infection which has remained prevalent in these areas for decades.
The report by the Lancet Global Health Journal indicates that after reviewing the various research works, hypertension and other cardiovascular diseases could be caused by repeated severe malaria exposure, especially during childhood.
It, however, noted that this is most applicable to populations in rural areas in low-income and middle-income countries such as India and African countries, where it claims lifestyle, sociocultural, and economic changes are less likely to trigger blood pressure elevation.
The report said: “Malaria exposure, particularly repeated malaria episodes and severe malaria in childhood, has been reported to be a contributing risk factor for the development of hypertension and other cardiovascular diseases.
“The risk-factor profile could be the case for some African and Indian populations where malaria has been endemic for many decades.”
Research still limited
The journal, however, cautions against holding a conclusive view on the matter, saying the relationship between exposure to malaria and cardiovascular diseases such as high blood pressure is still limited.
It said the impact of malaria exposure on cardiovascular health was evaluated through an indirectly modulated “evolutionary selection in malaria-endemic areas.”
The report noted that one of the direct effects found was the extended elevation of pro-inflammatory cytokines, “which hurt cardiovascular health and lead to cardiovascular diseases.”
Pro-inflammatory cytokines are small proteins that are released by cells in the body to start and promote inflammation. They help the immune system respond to infections or injuries by causing redness, swelling, heat, and pain.
Although pro-inflammatory cytokines are helpful to the human body, an extended elevation causes the inflammation-promoting proteins to stay at high levels for a long time. This, when it occurs, can harm the heart and blood vessels, increasing the risk of cardiovascular diseases like heart attacks and strokes.
Aside from the risk of an extended elevation of pro-inflammatory cytokines, the report found that malaria exposure also has an indirect effect on genetic selection causing “specific mutations in the two pivotal enzymes (ACE mutation rs4646994 and ACE2 mutation rs2106809) of the human renin-angiotensin system.”
The report said certain tiny changes in two important enzymes of the body, ACE and ACE2, that control blood pressure can help protect children from getting very sick with malaria. These changes protect children from severe malaria by increasing levels of angiotensin II.
However, having higher levels of angiotensin II for a long time might lead to high blood pressure (hypertension) when these children grow up.
“This protection, which is thought to be due to resultant elevated plasma angiotensin II concentrations, has been hypothesised to predispose individuals to hypertension in adulthood.
“This hypothesis has only been evaluated in hospitalised severe malaria patients,” the report said.
Recommendations
Given the recent discovery of malaria’s impact on cardiovascular health, researchers have called for further investigation into infectious diseases as risk factors for elevated blood pressure and other cardiovascular disease.
The Lancet research recommended that identifying the impact of infectious disease on CVD can be helpful to the population in sub-Saharan Africa and Southeast Asia.
The study asked that funding be provided for robust population-wide research to ascertain the direct and indirect roles of malaria exposure in predisposing individuals to hypertension.
Such research, the study noted, should focus primarily on malaria-endemic areas.
The report said: “Many biological, sociocultural, economic, environmental, and nutritional risk factors have been scrutinised and traditionally attributed to this burgeoning increase in hypertension. However, infectious diseases, such as malaria, have not been sufficiently investigated as risk factors for elevated blood pressure and other cardiovascular diseases.
“This research would also help to delve deeper into the causes of pathogenesis for many non-communicable diseases that might be driven, at least partly, by various communicable diseases, particularly in low-income and middle-income countries.”
