It was May 31, 2021 when the World Health Organization (WHO) recognized January 30 as the World Neglected Tropical Diseases Day. Diseases that include dengue fever, Chagas disease, leishmaniasis, rabies, scabies, leprosy, Buruli ulcer and snakebite envenomation, among others.
Although the world day is only two years old, it was a few years ago when an international consortium interested in this type of disease began to promote it.
“But the term was coined around 2005 to create something like a brand image that grouped diseases that have a number of things in common,” he explains to EFESalud the head of the department of International Health, National School of Health, of the Institute of Health Carlos III (ISCIII), Israel Cruz kill
Neglected tropical diseases (NTDs) are caused by viruses, bacteria, fungi or parasites, they occur mainly in the most disadvantaged countries -tropical and subtropical- which affect “the poorest of the poor”, as the ISCIII researcher explains.
And they are called neglected, according to the WHO, because they barely appear in global health programs. Almost no resources are allocated to them, so they are “almost ignored by global funding agencies”, which perpetuates the situation.
The head of Tropical Medicine of Médecins Sans Frontières, Gabriel Alcobawho has been working in this field for a decade, highlights in a telephone conversation with EFESalut from Geneva that these pathologies lack visibility: “we lack tools or political will” to deal with them.
“These are diseases that are little known and together affect more than a billion people. In terms of public health, its impact is enormous”, adds Alcoba, who in 2021 drew up an MSF report on these pathologies.
They are registered mainly in rural, conflict areas and where access to drinking water and sanitation is difficult. Where there is no quality medical care, and all this is exacerbated, warns the WHO, due to climate change.
It is Buruli’s ulcer; Chagas disease; dengue and chikungunya; dracunculosis; echinococcosis; foodborne trematodiasis; human African trypanosomiasis; leishmaniasis; leprosy; lymphatic filariasis; mycetoma, chromoblastomycosis and other deep mycoses; onchocerciasis; rage; scabies and other ectoparasitosis; schistosomiasis; helminthiasis transmitted by soil; snakebite poisoning; taeniasis/cysticercosis; trachoma, and yaws.
And in Spain?
The ISCIII researcher points out that there are some of these neglected tropical diseases that are present in Spain such as leishmaniasis, both visceral and cutaneous. Its incidence in the country is not high and it is more associated with dogs, it is controlled and treated with drugs. Both types globally are among the STDs with the highest burden of disease.
Caused by Leishmania parasites, which are transmitted to humans by the bite of an infected sand fly, without treatment visceral leishmaniasis can be fatal. In the case of the skin it can cause stigmatizing facial scars, disabling injuries and disfigurement.
Another ETD that is registered in Spain natively is scabies. It affects not only very poor populations, who live in very precarious health conditions, it is also related to the lack of hygiene. Cases have occurred in homes for the elderly, camps, etc., says ISCIII researcher Cruz Mata.
And in Spain there are no more but there were and the experts are vigilant with the anger. “Globally, it’s an extremely complicated problem, especially in Africa, children bitten by dogs that are not vaccinated,” he says.
What is the most neglected in the world?
For Israel Cruz Mata it is difficult to point out which of all ETDs is the most neglected. He mentions the Buruli ulcer because it is one of those that causes the fewest cases and has the least incidence, only five or six thousand cases a year, mainly in Sub-Saharan Africa.
“It is probably one of the most neglected. And it is paradigmatic because the transmission mechanism is unknown. It is caused by a bacterium, it is known that this can be in the environment but it has also been described in some animals, from insects to crabs. It is probably acquired when there has been contact with not very clean water”, comments the researcher.
Buruli’s ulcer now it is a little more current, the researcher points out, because it has been described in more than 30 countries, among them, above all, Australia, where the casuistry has nothing to do with that of Africa.
And it is that on the African continent it happens in extremely poor populations, who live in precarious health conditions, with very limited access to water.
In Australia, however, it is increasing mainly among the retired population, who enjoy nature, play golf and commute.
It causes ulcerative skin lesions: the bacterium produces a toxin that destroys the skin, it also causes anesthesia, so you don’t feel it and it causes immunodepression.
What starts as a small lump develops into a large ulcer that can affect the bone, soft tissues as well. Although it can sometimes heal on its own, 25% of patients are disabled for life due to the large scar it causes.
It is treated with antibiotics for eight weeks and ideally every day the wound heals and sometimes it is not confirmed that a person is cured until a year later. This should usually be accompanied by physiotherapy treatment, explains Cruz Mata.
The least neglected, those caused by worms
On the contrary, the ones that have a little more attention even though they are also neglected are those caused by worms. The reason is because preventive treatments can be used for the population, “it’s an easy tool”. It is administered over a period of time and if a certain percentage of the population is covered, they are controlled.
The ISCIII researcher points out that while in other diseases the challenge is more intellectual in the sense that it is unknown how they are transmitted or there are no good diagnostic methods, in those caused by worms everything is “relatively easier”. For this reason, they are “less neglected”.
It is for example the schistosomiasis, an acute and chronic ETD for which at least 236.6 million people required treatment in 2019. Less than half received it: 105.4 million, according to the WHO. In severe cases it can cause, among others, obstruction of blood flow and portal hypertension.
And which neglected tropical diseases are the most serious?
It is not easy to point out which of all neglected tropical diseases is the most serious, but Cruz Mata indicates that in terms of mortality, of those that cause the most deaths is snakebite poisoning. About 140,000 deaths a year, in addition, 400,000 people are disabled.
“It is not an infectious disease but it shares everything. It happens mainly in tropical and subtropical areas, it mainly affects poorer populations, the poorest of the poorest, because bites are basically associated with walking barefoot or walking far from home without a flashlight; or in a job not in the best conditions”, explains the ISCIII researcher.
In fact, an important group of people who suffer from snakebites are farm workers in the areas between Ethiopia and Sudan. They have to harvest at night because of the hellish heat during the day.
“They take the cereal and cut it, the hand in this population there are a lot of bites on the left arm basically for reaching in the dark”, says the Spanish researcher.
The noma, may be the next one
The head of Tropical Medicine at MSF agrees with Israel Cruz Mata but also wants to emphasize the need to pay more attention to Chagas disease in addition to leishmaniasis.
It is caused by a parasite that affects between 6 and 7 million people, most of them in Latin America. It manifests itself with cardiac, digestive, neurological or combined alterations.
But also at name It is not yet in the ETD group, although MSF is confident that it will be and so has requested it. Treated in time it cures but nine out of ten people die in the first two weeks if they do not receive treatment. It mainly affects children living in poverty. It causes a bacterial infection that eats away the facial tissue, explains Alcoba.
The future of neglected tropical diseases
The WHO considers that much progress has been made in the field of STIs in the last decade, with almost 500 million people no longer at risk. In addition, 43 countries have eliminated at least one of the pathologies.
The WHO roadmap aims to eliminate at least one STD in one hundred countries, as well as reduce the number of people requiring medical interventions by 2030.