Developing countries and infectious disease

Definition

In 1980, 12.53 million people died from infectious diseases. In 1990, this total reached 11.28 million, and in 2000, 11.07 million. Improved medical science, the development of vaccines and treatments for deadly diseases, and improved education in developing nations contributed to a continued downward trend in global deaths from infectious diseases in the first two decades of the twenty-first century—10.53 million in 2005, 9.32 million in 2010, 8.26 in 2015, and 7.61 million in 2019. However, the COVID-19 pandemic significantly increased global infectious deaths in the early 2020s, with 11.98 million deaths in 2020 and 14.83 million deaths in 2021.

The majority of deaths caused by infectious diseases occur in developing nations. Preventable and curable illnesses like malaria, HIV, and tuberculosis kill millions of people each year, mostly in low-income countries with few healthcare resources. For children younger than five in these countries, infectious diseases cause between 50 and 80 percent of deaths. Poverty, lack of education, inadequate or absent clean water and sanitation systems, crowded living conditions, unsafe sex, limited health care facilities, and lack of vaccines lead to the disproportionate burden of infectious diseases in the developing world. The chronic infectious disease-related disabilities suffered by adults in their prime working years lead to more poverty, continuing the cycle for the next generation.

Respiratory infections, including tuberculosis and pneumonia; diarrheal illnesses; malaria; and human immunodeficiency virus (HIV) contribute most to the infectious disease death toll in economically impoverished areas of the world; these and other infections, including the neglected tropical diseases, also contribute to substantial rates of chronic disease and disability.

Malaria

Malaria is a parasitic disease transmitted by the bite of the female Anopheles mosquito, which is endemic to more than eighty countries, including areas of Africa, Southeast Asia, Central America, South America, India, and parts of India and Oceania. Infection with any of the four species of Plasmodium causes fever, chills, and muscle aches, but the most dangerous kind of malaria, falciparum malaria, can cause serious disease in all ages. In 2023, 263 million malaria cases caused 597,000 malaria deaths, 76 percent of whom were under age five. The African continent accounted for 94 percent of these cases and 95 percent of the deaths.

The battle against malaria, a preventable and curable illness, is fought on two fronts: mosquito control and effective antimalarial medication. In developing countries, both methods have many inherent difficulties. Mosquito control has historically been approached by widespread use of insecticides, including dichloro-diphenyl-trichloroethane (DDT). Because of worldwide bans on the use of DDT, other approaches have been taken, including very limited use of DDT.

The main mosquito-control tool in campaigns against malaria is the insecticide-treated bed net (ITN), which keeps mosquitoes away from people who are sleeping at night, the time when biting mosquitoes are most active. According to data from the World Health Organization (WHO), access to ITNs varies greatly by country. In Djibouti, only 6.9 percent of the population had access to ITNs in the early 2020s, while 84 percent of the individuals living in the Democratic Republic of the Congo had access. In 2000, only 5 percent of households in sub-Saharan Africa owned one ITN, but by 2022, WHO reported 70 percent of households had at least one ITN and 40 percent had two. These significant improvements were aided by expanded international funding of malaria control programs to help meet the goal of the United Nations (UN) to decrease childhood mortality by two-thirds by 2015; this effort was part of the UN Millennium Development Goals program. In 2010, 145 million nets were distributed. Such efforts continued in 2012 when new Sustainable Development Goals were outlined, aiming to eradicate malaria in thirty-five countries and reduce global malaria mortality by 90 percent by 2030. The WHO estimated that between 2000 and 2022, prevention efforts avoided 2.1 billion cases of malaria and 11.7 million deaths.

The other major goal of malaria control campaigns is the widespread availability and use of artemisinin drugs to treat malaria. Although older malaria drugs, such as quinine and chloroquine, are inexpensive and available in most developing countries, the malaria parasites have developed resistance to these drugs, rendering them ineffective in many areas of the world. Artemisinin drugs, though more expensive, are much more effective as long as they are used in combination with a second drug; otherwise, resistance will quickly develop. The use of these combination drugs is called artemisinin-based combined therapy (ACT). Because some signs of resistance to artemisinins have been reported in Southeast Asia, WHO carefully monitors malarious countries for the presence of artemisinin resistance to quickly contain it if found. International funding continues to go to agencies working on wider access to artemisinins in 2022, such as WHO's twenty recommended interventions for fighting antimicrobial resistance.

HIV and Tuberculosis

In 2023, 39.9 million people worldwide were living with HIV, and a disproportionate number of them resided in developing countries. HIV has been historically most prevalent in sub-Saharan Africa, with women accounting for the majority of new infections.

As more girls and women become infected, more newborns will become infected with maternally transmitted HIV. Left without treatment, 25 to 30 percent of newborns will contract HIV from a mother who tests positive. Transmission also occurs through breast milk in 10 to 15 percent of untreated cases, which is the only economical way to nourish infants in many impoverished areas. Decreasing the risk of mother-to-child HIV transmission requires only one dose of an antiretroviral drug during labor and one dose for the newborn to significantly reduce the risk of transmission during childbirth. By 2019, antiretroviral therapy was available to 85 percent of women globally.

Maternal and paternal deaths from acquired immunodeficiency syndrome (AIDS), the advanced stage of HIV infection, resulted in an enormous increase in the number of so-called AIDS orphans in developing nations during the late 1990s and early 2000s. Between the early 1980s and the mid-2020s, around 14 million children worldwide lost one or both parents to AIDS.

In 2010, 58 percent of pregnant women received treatment to prevent transmission of HIV to their child during birth. By 2014, around 70 percent received treatment, and in the 2020s, between 80 and 85 percent of pregnant women received antiretroviral medication. Though advancements in antiretroviral medication greatly lowered transmission to newborns between the mid-2010s and the mid-2020s, life-saving treatment and care continued to be less common for children than for adults. On average, 52 percent of children received life-saving treatment in 2022, compared to 76 percent of adults who received antiretrovirals.

Outside Africa in the early and mid-2020s, areas of concern included Asia, especially Thailand, Indonesia, the Philippines, Lao PDR, Cambodia, Myanmar, and Vietnam. Contributing to dramatically increased rates of HIV infection in these areas are the sex trade, a lack of condom use, stigmatization of HIV testing, and the transient population.

A surge in the number of new cases of tuberculosis (TB) accompanied the HIV epidemic in both developed and undeveloped countries, but the latter were particularly unprepared to deal with increases in this serious disease. Some of these cases represent strains of TB that are resistant to many of the existing tuberculosis drugs. Asymptomatic TB infection is common in developing countries; when a healthy person inhales Mycobacterium tuberculosis, the body effectively walls off the infection in the lung, and the infected person does not become ill or contagious. As that person is infected with HIV, which gradually destroys the immune system, however, inactive TB becomes active, causing cough, fever, weight loss, and death if untreated. Coinfection with HIV and TB is a disabling, deadly combination.

Treatment of TB requires accurate diagnosis, which is often unavailable in undeveloped areas, and also requires long-term compliance with a daily medication regimen. Both factors contribute to the increase in new infections and incompletely treated infections. With the HIV epidemic in these areas, tuberculosis has become a priority in many disease-control programs.

In 2022, tuberculosis (TB) reemerged as the deadliest infectious disease, causing 1.32 million deaths in 2022 and 1.25 million deaths in 2023. International efforts to contain the upsurge in TB focused on prevention, testing, and treatment. Prevention has focused on safer sex practices and the empowering of girls and women to avoid sexually transmitted infections.

Diarrheal Illness and Measles

Diarrheal illness and its nearly inevitable complications of dehydration and malnutrition are large contributors to the disease burden in developing countries, particularly in children younger than age five. While diarrhea is considered a minor, self-limiting illness in the developed world, in undeveloped countries, diarrhea is the third leading cause of death among children under five and the leading cause of malnutrition. Diarrhea can be caused by many types of viruses, bacteria, and protozoa, but it is mostly a result of impure drinking water and fecal contamination of the living environment.

Even with access to decent sanitation and clean water, a child who does contract a diarrheal illness in a developing country is much less likely to have access to simple treatments that could save their life. One simple diarrhea treatment strategy that can save lives includes giving an ill child oral rehydration with a salt solution (often called ORS) and a zinc supplement while feeding the child to avoid malnutrition. WHO and other public health entities also launched social marketing campaigns encouraging the stigmatization of defecation in public (a significant problem in India, in particular) and encouraging handwashing with soap to avoid infection.

Immunization with rotavirus vaccine is another strategy that can decrease diarrhea in children. Better access to measles vaccines might also reduce the number of deaths from childhood diarrhea, as diarrhea is often a debilitating symptom of measles in very young children.

Measles affects children in undeveloped countries significantly more than in developed countries, primarily because, in developed countries, measles vaccination is routine at age twelve to fifteen months (with a booster at school entrance in most developed countries). Vaccination of young children in some areas of Africa and Asia has been limited.

In the 2020s, measles was still a common and fatal disease in developing nations. The Measles Initiative, a consortium including the American Red Cross, the United Nations Foundation, the Centers for Disease Control and Prevention (CDC), United Nations Children’s Fund (UNICEF), and WHO, committed to reducing measles worldwide by 90 percent by 2010, and by 2000, the initiative prevented 15.6 million deaths through vaccination. As a result, 84 percent of the world's children were immunized. The biggest impact was seen in Africa and the eastern Mediterranean region, including Afghanistan, Iran, Iraq, Pakistan, and Somalia. However, globally in 2018, the number of reported measles cases increased by 170 percent, according to the CDC. Despite this increase, between 2000 and 2018, an estimated 23.2 million deaths were prevented by vaccines.

For children not immunized and who are infected with measles, the disease can manifest as a mild respiratory infection, or it can be a serious illness. Serious complications of the infection include pneumonia, ear infection, blood abnormalities, and encephalitis (inflammation of the brain), which can cause permanent neurologic effects or death.

Neglected Tropical Diseases

Neglected tropical diseases (NTDs) infect billions of people worldwide, yet they are often unknown in developed countries. As a result, less funding has been allocated to NTDs for disease control or elimination programs. However, attention to NTDs increased somewhat in the later decades of the twentieth century. The NTDs contributing the largest burden of disease are lymphatic filariasis (elephantiasis), onchocerciasis (river blindness), schistosomiasis, soil-transmitted helminth (worm) infections, and trachoma.

Lymphatic filariasis (LF) is a disfiguring disease caused by thin, microscopic worms and is transmitted by mosquito bites. The tiny worms live in and damage the lymphatic system and, after long periods of time, can result in severe swelling of the arms, legs, breasts, and genitalia, leading to substantial disability. When chronically swollen areas become thickened and hardened, the resultant condition is referred to as elephantiasis. People in eighty-three countries were at risk of developing LF, primarily in tropical and subtropical areas of India, Indonesia, Bangladesh, and Nigeria. In 2000, the WHO launched its Global Programme to Eliminate Lymphatic Filariasis (GPELF), which reduced the prevalence of the disease by about 75 percent by the 2020s. The GPELE delivered around 9.7 billion treatments to more than 940 million people, significantly decreasing the risk of illness in many countries. LF is treatable with annual doses of inexpensive antiparasitic drugs, including albendazole and diethylcarbamazine, which do not kill adult worms in the body but kill the immature worms that can transmit the disease person-to-person through mosquito bites and thereby interrupt the cycle of transmission. Despite significant progress, over 650 million people in thirty-nine countries remained at risk in the mid-2020s.

Onchocerciasis, also known as river blindness, is transmitted between people by the bite of a black fly. The disease causes skin rashes with intense itching and eye damage that can result in blindness. An annual dose of the drug ivermectin can prevent the disease. Onchocerciasis affects millions of people in thirty-one countries in Africa, as well as Brazil, Venezuela, and Yemen. However, WHO efforts helped several countries eliminate the disease from their populations between 2013 and 2016, including Colombia, Ecuador, Mexico, and Guatemala.

Schistosomiasis affects more than two hundred million people in seventy-eight countries. It is caused by a parasite called a fluke, which lives in freshwater snails and causes several different syndromes in humans; these syndromes can result in kidney, bladder, and liver disease, and death.

Soil-transmitted helminths (worms like whipworms, hookworms, and Ascaris), also called geohelminthiasis, cause malnutrition, vitamin deficiencies, anemia, and intestinal obstruction in more than 1.5 billion people worldwide, with many more persons at risk. These parasites cause infections in nearly 25 percent of the world’s population each year. It is easily treated by administration of mebendazole or albendazole twice yearly.

Trachoma is a bacterial infection of the eye caused by Chlamydia trachomatis, which causes scarring of the lining of the upper eyelid and leads to blindness. It is spread from person to person by direct contact and affects more than eighty-four million people in fifty-five countries. The International Trachoma Initiative is dedicated to eradicating this disease by using a treatment and prevention strategy known as SAFE: surgery, antibiotics, face-washing hygiene, and environmental changes.

Impact

Infectious diseases in developing countries remain a huge global problem. Recognizing their responsibility to respond in a humanitarian way, many of the wealthy nations of the world are committed to finding solutions to these diseases. WHO, the Global Health Council, UNICEF, and other international organizations are working toward disease eradication, with polio and measles the most likely initial targets for eradication. National efforts, such as the US President’s Emergency Plan for AIDS Relief (PEPFAR), which was reauthorized in 2008, continued to provide economic aid to programs researching ways to control HIV/AIDS, tuberculosis, malaria, and other diseases worldwide.

Bibliography

Abdool, Karim S. S., et al. “HIV Infection and Tuberculosis in South Africa: An Urgent Need to Escalate the Public Health Response.” The Lancet, vol. 374, no. 9693, 2009, pp. 921–33, doi.org/10.1016/s0140-6736(09)60916-8. Accessed 28 Feb. 2023.

"Access to Antiretroviral Therapy in Africa Status: Report on Progress towards the 2015 Targets." World Health Organization and UNAIDS, 2015, www.unaids.org/sites/default/files/media‗asset/JC2702‗GARPR2015guidelines‗en.pdf. Accessed 10 Jan. 2025.

Batterman, S., et al. “Sustainable Control of Water-Related Infectious Diseases: A Review and Proposal for Interdisciplinary Health-Based Systems Research.” Environmental Health Perspectives, vol. 117, no. 7, 2009, pp. 1023–32, doi.org/10.1289/ehp.0800423. Accessed 10 Jan. 2025.

"Data on the HIV Response." Global Health Observatory, World Health Organization, www.who.int/data/gho/data/themes/hiv-aids/data-on-the-hiv-aids-response. Accessed 10 Jan. 2025.

"Diarrhoeal Disease." World Health Organization, 7 Mar. 2024, www.who.int/news-room/fact-sheets/detail/diarrhoeal-disease. Accessed 10 Jan. 2025.

Greenwood, Brian M., et al. “Malaria: Progress, Perils, and Prospects for Eradication.” Journal of Clinical Investigation, vol. 118, no. 4, 2008, pp. 1266–76, doi.org/10.1172/jci33996. Accessed 10 Jan. 2025.

"Lymphatic Filariasis." World Health Organization, www.who.int/news-room/fact-sheets/detail/lymphatic-filariasis. Accessed 10 Jan. 2025.

"Malaria." World Health Organization, www.afro.who.int/health-topics/malaria. Accessed 10 Jan. 2025.

Orenstein, Walter A., et al. Plotkin’s Vaccines. 8th ed., Elsevier, 2024.

Packard, Randall M. The Making of a Tropical Disease: A Short History of Malaria. 2nd ed., Johns Hopkins UP, 2021.

"Poverty and Infectious Disease Come Together Far Too Often—the Solution Could Be Data-Driven." World Economic Forum, 15 Mar. 2023, www.weforum.org/stories/2023/03/poverty-and-disease-come-together-far-too-often-the-solution-could-be-data-driven. Accessed 9 Jan. 2025.

Santosham, Mathuram, et al. “Progress and Barriers for the Control of Diarrhoeal Disease.” The Lancet, vol. 376, no. 9734, 2010, pp. 63–67, doi.org/10.1016/s0140-6736(10)60356-x. Accessed 9 Jan. 2025.