Locust plague threatens food security and accentuates famine and malnutrition; Once again, climate change is the culprit.


Then from the smoke came locusts on the earth, and they were given power like the power of scorpions of the earth.”

Revelation 9:3-4

It seems that the present days breathe life into this Apocalyptic scene. At the same time when coronavirus pandemic threatens the “civilized” world and spreads rapidly and exponentially all over the planet, developing countries in Southwest Asia, Arabian Peninsula and East Africa suffer the dual perils of SARS-CoV2 and a dreadful locust plague.1The infestation by swarms of locusts occurred soon after the Australian bushfire season of 2019-2020 and in some of the afflicted countries is considered to be the worst in the last 70 years.1 Available data suggest that southern Iran, Pakistan, Yemen, Saudi Arabia, Oman, Kenya, Ethiopia, Somalia, south Soudan and Uganda are among the countries that are being hit particularly hard by this recent outbreak. This means that the threat of food security is not but a reality for over 450 million people residing in these areas.

Meanwhile, we should be aware that desert locusts are not just grasshoppers. Whereas they both have the same appearance and locusts belong to the grasshopper family of Acrididae, their main difference lies in the fact that locusts have the capacity to change their morphology and color, to migrate over large distances and most importantly, have the ability to exhibit two distinct behavioral patterns (solitary and gregarious).2 When in the solitary phase, locusts act as individuals. However, under certain conditions they change their behavior rapidly to become more abundant and gregarious, and act as a unit.3 More specifically, adult locusts can form dense swarms that contain thousands of millions of individuals that fly at a speed of 16-19 km/hour depending on the wind and travel about 5-130 km, or more, in just a day.3 In their passage they destroy vast areas of crops and livelihood, as these historic pests could eat as much as their own weight (equal to about 2 grams for a locust) per day and 40 million locusts (contained in about a 1 km2 size swarm) could consume the same amount of food as about 35,000 people, in just one day!3

 In most countries the situation remains uncontrollable and Somalia has already declared a National Emergency as the pest upsurge “poses a major threat to Somalia’s fragile food security situation”.4 Having feared the decimation of the crops and the subsequent humanitarian crisis, the United Nations Central Emergency Response Fund (CERF) approved a loan of about 10 million dollars to the Food and Agriculture Organization (FAO) to set up an immediate and coordinated response to fight desert locusts in the afflicted East African countries. What is really worrying is the fact that FAO officials forecasted that the situation is to be deteriorated further in the upcoming months since the climatic conditions are expected to facilitate the breeding, the hatching and the development of new swarms.5 In an attempt to control and eradicate the pests’ attacks, locust experts in cooperation with local governments, have trained and dispatched young adults to constantly conduct surveillance and air-ground control operations by applying chemical pesticides.

At this point we should mention that the need to balance the risks of locust invasion against the use of pesticides is especially highlighted by FAO’s authorities, since it is known that the chemical pesticides may have adverse effects both on human health and on natural ecosystems.6 Indeed, besides the fact that locust pheromones released in the air during their mating season can act as allergens and exacerbate or even cause asthma in about one to two years after initial exposure,7,8 there is compelling evidence – coming from studies among farmers – that high levels of exposure to chemical pesticides are associated to asthma. 8 The mechanisms behind the signaling pathways that link pesticide exposure to asthma development or exacerbation have not yet been fully elucidated. However, it is suggested that pesticides interact with and augment the expression of genes that increase susceptibility to asthma.9

Clearly, swarm effects will be detrimental for human health not only in terms of allergies and asthma development, or exacerbation. Food security, that is already nebulous in these areas, is further threatened. This certainly encloses a risk for the economy of low-income and debt-distress African countries as export earnings from agricultural commodities are to be declined significant. This is an especially important parameter for the poor countries whose 65% of Gross Domestic Product (GDP) depends heavily on agriculture. The following social unrest from misery and hunger may be just around the corner for local populations. While this could be a real headache for governmental economists and politicians, physicians should strive to combat famine and malnutrition, as this is one of the top global challenges and ethical priorities of the medical community.10

            Reduced productivity in slow-growing economies raises food prices and exacerbates poverty that in turn begets famine and malnutrition.11 Surprisingly, although we are already going through the second decade of the 21st century, hunger and malnutrition remain significant problems, especially in the underdeveloped countries. Nowadays, this is a stark reality for more than 462 million people worldwide. It is known that malnutrition ranges from undernutrition and micronutrient deficiencies, to extra body weight and obesity.12According to a report from the World Health Organization (WHO) elder people, women, infants, children and adolescents are considered to be highly susceptible groups. Interestingly, around 45% of deaths among children under 5 years of age are linked to undernutrition, especially in low- and middle-income countries. Muscle wasting increases the risk of death among young children whereas stunting is a barrier for both physical growth and cognitive development.12 Actually, consequences could be detrimental for the function and recovery of every organ system. Body weight loss driven by prolonged starvation is a trigger for changes in body composition. Muscle function and muscle mass as well as fat adipose tissue decline and lead to a brittle metabolic state.13 The same applies to the cardiac muscle which leads to a reduction in cardiac output and a subsequent decrease in renal perfusion and glomerular filtration rate.13 The gastrointestinal system may also be affected. Debilitating diarrhea secondary to chronic malnutrition and malabsorption is one of the most common causes of morbidity and mortality in the developing world.13 Likewise, impaired immunity and delayed wound healing among malnourished patients make them highly susceptible to infections.14 The need for enteral or parenteral nutrition may be imperative for the treatment of severe caloric and micronutrient deficiencies.15 Therefore, the preparedness and stability of healthcare systems worldwide is crucial to the battle against such humanitarian crises as the prolonged hospital stay of the malnourished patients may be a huge downturn for the already damaged economies.16

The link between the ongoing climate change and the current locust outbreak is undeniable. According to a senior locust forecasting officer at the FAO, Keith Cressman, bizarre cyclones formed and hit the Horn of Africa during the last two years, creating the perfect breeding conditions for Desert Locusts. The increased frequency of these unusual cyclones was attributed in part to the global warming caused by increased greenhouse gas emissions. Interestingly, climatologists highlight that the Arabian Sea and the West Indian Ocean were warmer than usual lately.17 Besides, climate change has also accentuated the phenomenon of Indian Ocean Dipole (IOD) which is also to be blamed partly for the continuing locust invasion in the region. The IOD (also known as the Indian Niño due to its similarity to its Pacific equivalent) is a natural climate phenomenon that occurs non-periodically across the two sides of the Indian Ocean.18 This phenomenon which was initially identified by climate researchers in 1999,19 encompasses an oscillation of sea surface temperatures between warm (positive phase) and cold (negative phase) in the eastern part of the ocean coupled with positive, neutral and negative cycling phases in the western part.20 Given the fact that 2019 was the second hottest year of the last decade,21 a supercharged IOD contributed significantly to the severe droughts and wildfires observed in Australia and to the unprecedented heavy rainfalls and floods that hit Africa and Middle East. As Desert Locusts rarely lay their eggs in dry or nearly dry soil, they travel to moist areas where the ground is wet enough for their eggs to hatch.3 Current climatic conditions in the area are optimal for the reproduction and development of new swarms making the threat for a second invasion a sad reality perpetuating poverty and malnutrition.

It is crucial for physicians to recognize the causes behind their patients’ frailty and illness. “The How and the Why”… Climate medicine is making its presence felt more and more. Physicians need to be aware and act emergently to be ready to face the challenges of the future. As all humans, they have an ethical obligation, too. Let’s not forget the quote of Eleanor Roosevelt, who served as the First Lady of the United States from 1933 to 1945 and as the First Chair of the United Nations Commission on Human Rights: “The freedom of man, I contend, is the freedom to eat”.


  1. Funding gap for locust crisis. Nat Food. 2020;1:143. 
  2. Topaz CM, D’Orsogna MR, Edelstein-Keshet L, Bernoff AJ. Locust dynamics: behavioral phase change and swarming. PLoS Comput Biol. 2012;8:e1002642. 
  3. Symmons PM, Cressman K. Desert Locust Guidelines (FAO, 2001).
  4. East Africa is reeling from an invasion of locusts. The Economist. January 2020.
  5. The FAO Desert Locust Bulletin, April 2020.
  6. Fighting the locusts safely…Safely pesticides in desert locust control: balancing risks against benefits. FAO, 2005.
  7. Pener MP. Allergy to locusts and Acridid grasshoppers: a review. Journal of Orthoptera Research, 2020;23:59-67.
  8. Hawley B, Cummings KJ, Mohammed M, Dimmock AE, Bascom R. Allergic sinusitis and severe asthma caused by occupational exposure to locust bean gum: Case report. Am J Ind Med. 2017;60:658–663. 
  9. Amaral AF. Pesticides and asthma: challenges for epidemiology. Front Public Health. 2014;2:6.
  10. Von Braun J. Food insecurity, hunger and malnutrition: necessary policy and technology changes. N Biotechnol. 2020;27:449-52.
  11. Webb P, Stordalen GA, Singh S, Wijesinha-Bettoni R, Shetty P, Lartey A. Hunger and malnutrition. BMJ 2018;361:k2238.
  12. Fact sheets; Malnutrition. WHO, 2018.
  13. Saunders J, Smith T. Malnutrition: causes and consequences. Clin Med (Lond). 2010;10(6):624–627. 
  14. Stratton R, Green CJ, Elia M. Disease-related malnutrition: an evidence-based approach to treatment. Oxon: Cabi Publishing, 2003.
  15. Gorospe EC, Oxentenko AS. Nutritional consequences of chronic diarrhea. Best Pract Res Clin Gastroenterol.2012;26:663-75.
  16. Curtis LJ, Bernier P, Jeejeebhoy K, Allard J, Duerksen D, Gramlich L, Laporte M, Keller HH. Costs of hospital malnutrition. Clin Nutr 2017;36:1391-1396.
  17. Roxy Matthew Koll and Chaithra ST. Impacts of climate change on the Indian Summer Monsoon. Climate change and water resources in India. Eds Vimal Mishra, JR Bhatt.
  18. Rao, S. A. et al. Why is Indian Ocean warming consistently? Clim. Change 2012;110:709–719.
  19. Webster, PJ, Moore, AM, Loschnigg, JP, Leben, RP. Coupled ocean–atmosphere dynamics in the Indian Ocean during 1997–98. Letters to Nature. 1999;401:356–360.
  20. Swapna, P., Krishnan, R. & Wallace, J. Indian Ocean and monsoon coupled interactions in a warming environment. Clim. Dyn. 2014;42:2439–2454.
  21. NOAA National Centers for Environmental Information, State of the Climate: Global Climate Report for Annual 2019, published online January 2020, retrieved on March 14, 2020 from