Africa makes big steps against neglected diseases; one of them nearly took down Tour de France winner Froome

Caused by a variety of bacteria, viruses, protozoa and helminths, Africa accounts for 90% of the disease burden, but might just win the battle

CHRIS Froome won the Tour de France Sunday for a second time in three years, crossing the finish line in Paris after covering more than 2,000 miles in three weeks. The 30-year-old Briton, who was born in Kenya, won by 1 minute, 12 seconds over Colombia’s Nairo Quintana.

Froome began his cycling career riding a mountain bike on a bumpy road near Kenya’s capital Nairobi with his mother driving alongside him. In 2008, he rode his first Tour de France, finishing 84th.

But during Froome’s first year with Team Sky in 2010, his career was set back when he contracted schistosomiasis, a parasitic disease also known as bilharzia, from drinking contaminated water on a visit back to Africa, VeloNews reported in 2011.

The disease, which went undiagnosed for a year, affected his performance and he was initially offered less than $155,000—below the average pro rider salary—to stay at Sky in 2012, according to Richard Moore, author of a book about the team, “Sky’s the Limit.”

That year, after beating the illness, he regained form and began to show he was the strongest rider in the mountains; he first won the Tour in 2013.

Froome’s episode with bilharzia has helped add the spotlight on what are termed neglected tropical diseases (NTDs), a group of chronic debilitating – and sometimes deadly – diseases affecting more one billion people worldwide, mainly in Africa.

 Beyond their negative impact on health, NTDs contribute to an ongoing cycle of poverty and stigma that leaves people unable to work, go to school or participate in family and community life. 

In the context of the Millennium Development Goals (MDGs), the NTDs were neglected relative to the “big three” diseases (HIV/AIDS, malaria and tuberculosis) in large part because the burden of NTDs tends to be limited within poor, rural and otherwise marginalised populations.

But they have now been included in the third proposed Sustainable Development Goals, which seek to “end the epidemics of AIDS, tuberculosis, malaria, and neglected tropical diseases and combat hepatitis, water-borne diseases, and other communicable diseases” by the year 2030.

The inclusion of NTDs is important, as over 90% of the disease burden for NTDs is in Africa, and the 17 diseases account for a disease burden of at least 26 million disability-adjusted life years, around half the burden of tuberculosis or malaria.

But Africa has made huge strides in combating the diseases over the past two decades, and now looks poised to eliminate some of them in the next few years. We put the spotlight on some of the most debilitating, drawing from the latest WHO report on NTDs:

- Schistosomiasis – which Froome recovered from – is a chronic parasitic disease caused by infection with several species of blood flukes of the genus Schistosoma. Infection occurs when the larval forms of the parasite, released by freshwater snails, penetrate human skin in water, causing an infection of the intestine or urinary tract.

WHO recommends surveillance and preventative chemotherapy to break the chain of transmission. An estimated 250 million people required preventive medication for schistosomiasis in 2012, 93% of them in sub-Saharan Africa. The region accounted for 84.5% of the global number of people treated in 2012, a 60% increase from the previous year. But scale-up of treatment is still slow in the 10 highest-burden African countries.

- Dengue fever is a mosquito-borne viral infection caused by a virus that occurs in tropical and subtropical regions worldwide. The disease is transmitted mainly by female Aedes aegypti mosquitoes; infection causes flu-like illness, and occasionally develops into a potentially lethal complication called severe dengue, previously known as dengue haemorrhagic fever.

Eliminating dengue in Africa has been hampered by the lack of data, as most cases are misdiagnosed for malaria, which has similar symptoms. Since 2013, dengue outbreaks have been reported in Angola, Mauritius, Mozambique and Tanzania. But the widespread roll-out of insecticide treated bed nets is helping reduce transmission.

- Trachoma is a bacterial infection caused by Chlamydia trachomatis. Transmission occurs through contact with eye discharge from infected people, particularly young children; infection is also spread by flies. Untreated, this condition causes the eyelashes to turn inward and grow towards the eye (medically termed trichiasis), resulting in severe irritation, corneal opacities and blindness.

Africa accounts for 18 million cases of active trachoma, 85% of all cases globally,  and 3.2 million cases of trichiasis (44% of all cases globally). Ethiopia and South Sudan have the highest prevalence of active trachoma; in addition to blindness, trichiasis causes pain every time a person blinks.

But investments in water and sanitation go a long way in preventing the disease, and trichiasis surgery remains one of the most cost-effective interventions to combat loss of vision. At about $40 per surgery, it is also very affordable. An early estimate of the backlog of cases (almost 5 million cases) suggested that $200 million may be needed between 2011 and 2020 to eliminate the disease.

- Buruli ulcer is a chronic debilitating skin infection caused by Mycobacterium ulcerans. Infection can lead to permanent disfigurement and disability. Patients who are not treated at an early stage of the infection suffer severe destruction of the skin, bone and soft tissue.

The number of cases of buruli ulcer has been decreasing in Benin since 2007 and in Côte d’Ivoire since 2010, but increasing in Ghana and Gabon. If targets of coverage and value for money are to be met, about $4.3 million per year may be required during 2015–2030 for active case-finding, diagnosis, treatment and care, including medicines and surgery when necessary.

- Yaws is a chronic bacterial infection that mainly affects the skin and bone. In 2012, WHO developed a new strategy for yaws eradication by 2020, which relies on delivering mass treatment to entire endemic communities irrespective of the number of active clinical cases, followed by regular surveillance until clinical cases are no longer identified.

The antibiotic azithromycin used in mass treatment can interrupt transmission within 6–12 months, one study in Nsukka, Nigeria demonstrated. In selected districts in the Congo and Ghana, mass treatment covering 90% of the population also interrupted transmission.

- Human African trypanosomiasis (sleeping sickness) is a protozoan parasitic disease spread by the bites of tsetse flies in much of rural sub-Saharan Africa. Without prompt diagnosis and treatment, the disease is usually fatal as the parasites multiply in the body, cross the blood–brain barrier and invade the central nervous system.

An animal health worker injects a cow with diminazen to treat trypanosomiasis (sleeping sickness). (Photo/Flickr/ US Army Africa).

From 2000, WHO intensified control measures by deploying mobile teams to screen entire populations in vast areas of the continent believed to harbour the disease. This strategy reduced the prevalence from 300,000 in the 1990s to fewer than 7,000 cases in 2013 – a staggering 97% decline.

The Democratic Republic of the Congo (DRC) is the only country reporting more than 500 new cases annually; it accounts for 89% of the cases reported in 2013. WHO estimates show that active case-finding and treatment and care may require investments of about $13.5 million per year during 2015–2030.

- Dracunculiasis (guinea worm disease) is a crippling parasitic disease caused by infection with Dracunculus medinensis, a long thread-like worm. Transmission occurs exclusively by drinking water contaminated with parasite-infected water fleas.

Progress towards global eradication continues to be substantive - 2013 saw a record 73% decline in the annual number of cases, to 148, compared with the 542 cases reported in 2012. 

This decrease was largely driven by the 78% decline in the number of cases in South Sudan, from 521 to 113 cases, but Chad, Ethiopia, Mali and Sudan reported a slight increase during that time.Still, insecurity in South Sudan and some parts of Mali is interrupting eradication efforts.

- Leishmaniases are protozoan parasitic infections transmitted through the bites of infected female sandflies. Visceral leishmaniasis (also known as kala-azar) attacks the internal organs and is the most severe form. Cutaneous leishmaniasis commonly causes ulcers of the face, arms and legs, leaving severe and permanently disfiguring scars and disability.

The medicines traditionally used to treat patients with visceral leishmaniasis have proven too costly, too toxic and of limited efficacy, but a new regimen introduced a few years ago proved effective and easier to administer. Thanks to a WHO-brokered donation of the drug by the manufacturer, Ethiopia, Sudan and South Sudan have incorporated it in their control strategies.

- Rabies is a preventable viral disease that is mainly transmitted to humans through the bite of an infected dog. Once symptoms develop, rabies is invariably fatal in humans unless they receive prompt treatment. Unfortunately, investment in dog vaccination to eliminate rabies from endemic countries in Africa and most of Asia has been minimal to date.

But large-scale vaccination projects are underway in South Africa and Tanzania; as well as smaller ones in Lesotho, Mozambique and Swaziland. Still, the cost of vaccination is often far out of reach for very poor communities, it can reach $11.27 per dog; WHO is working with partners to finance the vaccinations and bring costs down.

- Leprosy is a complex bacterial infection caused by the bacillus Mycobacterium leprae. The disease mainly affects the skin, peripheral nerves, mucosa of the upper respiratory tract and the eyes. Leprosy is cured easily using multidrug therapy.

The number of cases of leprosy in the African region has dropped from 34,480 in 2006 to 20,911 in 2013. The biggest decline has been in the DR Congo, which registered a 54% decline during that time.

- Lymphatic filariasis (elephantiasis) is a severely debilitating, disfiguring and stigmatising disease caused by infection with one of three species of nematode, which are transmitted by mosquitoes. Adult worms live almost exclusively in humans, lodging in the lymphatic system. The infection is commonly acquired during childhood but usually manifests during adulthood as abnormal enlargement of the limbs and the genitals.

Four countries with the heaviest burden in Africa – Nigeria, Tanzania, Ethiopia and DR Congo – are scaling up mapping and surveillance of the disease, but 464 million in 33 countries on the continent are living in areas that require interventions to eliminate lymphatic filariasis. Togo completely eliminated the disease in 2010 by mass door-to-door treatments.

- Onchocerciasis (river blindness) is caused by infection with a filarial nematode; transmission in humans occurs from the bites of infected blackflies that breed in fast-flowing rivers and streams, mostly in remote rural villages located near fertile land where people rely on agriculture. The adult worms produce tiny larvae that migrate to the skin, eyes and other organs. Symptoms include severe itching and eye lesions that can lead to visual impairment and permanent blindness.

More than 99% of the about 37 million people infected with the disease live in 31 sub- Saharan African countries, representing about 120 million people at risk in 2012. By 2020, 12 countries are on course to have eliminated the disease –Niger, Senegal, Malawi, Burundi, Chad, Kenya, Mali, Benin, Guinea, Guinea-Bissau, Sierra Leone and Togo.

-Additional reporting by Alex Duff, Bloomberg


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