The inter-linkage between TB and malnutrition is bi-directional. While TB leads the patient to malnutrition, the risk of developing active TB increases due to malnutrition.
It is widely established, though through limited scientific studies, Tuberculosis (TB) has a critical effect on nutritional state. This has been evidenced in all the studies that have investigated body composition in the affected patients. Malnutrition perpetuates the morbidity of the disease and may even contribute to mortality, more so in impoverished and resource-poor settings where the overall nutritional status of the populace, even of the “healthy persons”, may be highly uncertain.
Even the World Health Organization (WHO) reiterates that TB remains one of the world’s deadliest infectious killers and poor nutritional status in communities only heightens morbid conditions, including possible fatalities.
As per the data of 2020, each day over 4,100 people lose their lives to TB and close to 28,000 people fall ill with this preventable and curable disease. Medical community and TB activists confirm that the COVID-19 pandemic has reversed many years of progress made earlier in the fight to end TB. TB deaths increased in 2020 for the first time in over a decade.
The inter-linkage between TB and malnutrition is dubbed as bi-directional. While TB leads the patient to malnutrition, on the other hand malnutrition increases the risk of developing into active TB almost six to ten times. Improving the nutritional status of individuals considerably reduces tuberculosis. Such co-relationships were assessed in many studies that included examination of the nutritional status and determinants of underweight TB patients.
Underweight is considered a malnutrition stage in which the Body Mass Index (BMI) of any adult is scored much less than the normal scales. Such a state of being underweight results from dwindling balance between the supply of nutritious food and the body’s demand for the basic nutrients. It is noteworthy that the conditions such as genetics, metabolic disorders and medication side effects in some cases, eating disorders and infection with tuberculosis predispose to underweight conditions.
As per available data, almost over one-quarter of TB cases in the world are as a result of malnutrition, thus improving the nutritional status of individuals’ considerably decreases the risk of TB. Additionally, malnutrition increases TB relapse and mortality; wherein the treatment outcomes of TB patients can be vastly improved by studying their nutritional status. Incorporating nutritional support during Directly Observed Treatment Strategy (DOTS) increases the probability of favourable treatment outcomes
A relatively recent comparative cross-sectional study (Feleke & Feleke et.al 2019) found that a very high proportion of TB patients were malnourished in their large sample. TB patients were highly susceptible to malnutrition and even a very distal factor for malnutrition became proximal for TB patients. The nutritional status of TB patients was affected by the site of infection, sex, residence, intestinal parasite infection and alcohol. Additional risk-factors such as poverty, high population density, overcrowding, food insecurity and Human Immunodeficiency Virus (HIV) further prepare the stage for both malnutrition and poor infection control.
Many practising clinicians and public health experts have long drawn the conclusion that malnutrition is an important risk factor for the development of tuberculosis. Malnutrition overwhelmingly affects Cell-Mediated Immunity (CMI), which is the principle host defense against the TB pathogen. Therefore, it surely makes biological sense.
Nationally-run TB prevention and treatment programmes, which well cover the ‘DOTS for TB intervention’, invariably, consider incorporating more nutritional support for the patients. This is because a significant number of TB patients were found malnourished in most research studies. In relatively poor resource settings, families cannot afford access to nutritionally appropriate food-intake and, therefore, administering the anti-TB drugs alone will drastically reduce the treatment success rate. In addition to nutritional food in-take, most researchers also recommend that the relevant TB guidelines should consider iron supplementation and de-worming as an integral part of the TB treatment.
Malnutrition and Pediatric TB
Tuberculosis remains a significant source of morbidity and mortality among children, especially in resource-limited settings. Child tuberculosis in India has been estimated to be around 10% of the total adult TB incidence; whereas only 6% of the total cases are children as reported to the Revised National Tuberculosis Control Programme (RNTCP). This figure of pediatric TB has remained nearly constant for the last decade. This data is well corroborated with the global figures of the total new tuberculosis infections each year, nearly 11%, of children. Multiple studies found that malnutrition is highly prevalent in children living in TB endemic nations and contributes to significantly higher number of deaths in children under-5 years of age across the globe.
It is established that the respiratory infections are among the highest and notorious contributors of morbidity and mortality in children. Because of such high rate and frequency, it provides an opportunity to further examine how malnutrition impacts the outcomes and risk of diseases spread by respiratory droplets such as tuberculosis. Malnutrition has been associated with increased risk of respiratory infections. A research study (prospective trial) in Bangladeshi children found that being underweight increased the risk of an upper respiratory infection by 13%, and wasting increased it by 20% (Zaman, Baqui, Yunus et.al)
As the respiratory infections are highly prevalent in children, a large body of evidence has emerged on associated risk factors for infections and poor outcomes, including the nutritional status. Although there are limitations in translating the risk of one pathogen to another, it has been observed that poor nutrition is associated with severe deficits in immunity, both inherent and cell-mediated. Thus, until further research is conducted on childhood tuberculosis, we can learn from past studies in children that suggest that malnutrition significantly worsens the risk and severity of respiratory disease.
It is time that the respective health providers, especially the national TB programmes, include addressing the nutrition issues in TB prevention, treatment and cure strategies.
(The author is Senior Consulting adviser, Strategic Communication & Programmes, with the UN system in Asia and the Pacific.)