By Amber Milne

LONDON, March 24 (Thomson Reuters Foundation) — Deadly viruses and diseases, like tuberculosis (TB) and malaria, have historically hit poorer nations harder as many are treatable or preventable and eliminated in wealthier nations.

So-called "poverty diseases" largely ravage low-income countries, with the situation made worse by the effects of poverty like poor nutrition and sanitation, lack of access to clean drinking water, and health education.

As governments globally race to contain and cure the coronavirus outbreak, poorer countries are gearing up to be hit hard if the virus gains foothold, with lessons learned from the likes of tuberculosis and Ebola.

With World Tuberculosis Day on Tuesday, here are seven diseases that hit vulnerable people the hardest:

1. Tuberculosis 

TB is a bacterial infection that infects millions each year, but where does it come from and how deadly is it?

TB has been around as long as 3 million years. When the discovery was announced in 1882 it was said that it killed one out of every seven people living in the United States and Europe, making it one of the most deadly infections in history. 

Although the disease is now preventable and curable, in 2018, 1.5 million people died and around 10 million people fell ill with TB, the vast majority of which were found in Africa and South Asia, where vaccine rates are the lowest in the world.

2. Ebola

Ebola, a virus transmitted to people from animals, is severe and often fatal, with fatality rates varying from 25% to 90% in past outbreaks.

The 2014-2016 West Africa outbreak, described by the World Health Organization (WHO) as "the largest and most complex Ebola outbreak since the virus was first discovered", infected over 28,000 and killed over 40% of those infected.

3. HIV

Up to 43.2 million people have died from AIDS-related illnesses since the start of the 1980s epidemic and today about 37.9 million people globally are living with HIV — more than two thirds of whom live in Africa.

Reaching key populations at risk for HIV transmission in Africa, like men who have sex with men or sex workers and their clients, can be particularly hard because of social stigma.

4. Malaria 

Malaria is a curable, preventable disease caused by parasites and transmitted through mosquito bites. While many Western countries have eliminated the disease entirely, more than 200 million new cases are reported each year.

Most cases in 2018, around 213 million, were found in Africa with around 70% of the world's malaria burden concentrated in 11 countries — India and 10 countries in Africa, home to 94% of malaria deaths in 2018. 

5. Measles 

Measles, a highly contagious respiratory viral disease which killed more than 140,000 people in 2018, can be prevented but has seen outbreaks in all regions because of slowing vaccination rates, particularly in the hardest hit countries of Africa.

"The fact that any child dies from a vaccine-preventable disease like measles is frankly an outrage and a collective failure to protect the world’s most vulnerable children," Dr. Tedros Adhanom Ghebreysus, director-general of the WHO, said.

6. Pneumonia 

Pneumonia, the largest cause of death in children worldwide, is common in African and South Asian countries like India, where the charity Save the Children estimates there were preventable child deaths from pneumonia every four minutes last year.

Although it can be prevented and treated at a low cost, complications from poverty like lack of access to vaccines and malnutrition have contributed to millions of preventable deaths in countries like India and Nigeria.

7. Diarrhoeal Disease 

Diarrhoeal disease is a major cause of child deaths and mostly comes from contaminated food and water sources, so hits countries without access to good sanitation, clean drinking water and safe food sources the hardest.

Although it can be prevented with interventions like washing hands with soap and clean water, in low-income countries diarrhoea is so widespread that children under three years old experience an average of three episodes every year.

(Reporting by Amber Milne; Editing by Belinda Goldsmith. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers the lives of people around the world who struggle to live freely or fairly. Visit http://news.trust.org)