It was May 31, 2021 when the World Health Organization (WHO) recognized January 30 as the World Day for Neglected Tropical Diseases. Pathologies among which are dengue, Chagas disease, leishmaniasis, rabies, scabies, leprosy, Buruli ulcer and snakebite poisoning, among others.
Although the world day is barely 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 would group diseases that have a number of things in common,” he explained to EFESalud. the head of the Department of International Health, National School of Health, of the Carlos III Health Institute (ISCIII), Israel Cruz Women
Neglected tropical diseases (NTDs) are caused by viruses, bacteria, fungi or parasites, they occur mainly in the most disadvantaged countries -tropical and subtropical- that affect “the poorest of the poor”, as explained by the researcher of the ISCIII.
And they are called neglected, according to the WHO, because they hardly appear in global health programs. Almost no resources are allocated to them, so they are “practically ignored by world funding agencies”, which perpetuates the situation.
The head of Tropical Medicine at Doctors Without Borders, Gabriel Alcobawho has been working in this field for a decade, highlighted in a telephone conversation with EFESalud from Geneva that these pathologies lack visibility: “there is a lack of tools or political will” to deal with them.
“These are diseases that are little known and together they affect more than a billion people. In terms of public health, its impact is enormous”, adds Alcoba, who in 2021 prepared an MSF report on these pathologies.
They are registered mainly in rural areas, conflict zones and where access to drinking water and sanitation is difficult. Where there is no quality medical care, and all this is aggravated, warns the WHO, by climate change.
This is the Buruli ulcer; Chagas disease; dengue and chikungunya; dracunculiasis; echinococcosis; foodborne trematode; human African trypanosomiasis; leishmaniasis; leprosy; lymphatic filariasis; mycetoma, chromoblastomycosis and other deep mycoses; onchocerciasis; Rage; scabies and other ectoparasitosis; schistosomiasis; soil-transmitted helminthiasis; snakebite envenoming; 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 leishmaniasisboth 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 NTDs with the highest burden of disease.
Caused by Leishmania parasites, which are transmitted to humans through the bite of an infected sand fly, visceral leishmaniasis without treatment can be fatal. In the case of skin, it can cause stigmatizing facial scars, disabling injuries, and disfigurement.
Another of the NTDs that is registered in Spain in an autochthonous way is scabies. It affects not only very poor populations, who live in very precarious health conditions, it is also related to a lack of hygiene. There have been cases in residences for the elderly, camps, etc., points out the ISCIII researcher Cruz Mata.
And in Spain there is no longer but there was and the experts are vigilant with the rabia. “Globally, it is an extremely complicated problem, especially in Africa, children bitten by dogs that are not vaccinated,” she says.
What is the most neglected in the world?
For Israel Cruz Mata, it is difficult to point out which of all the NTDs is the most neglected. He mentions Buruli ulcer because it is one of those that cause fewer cases and has a lower incidence, just five or six thousand cases a year, mainly in Sub-Saharan Africa.
“Surely it is one of the most neglected. And it is paradigmatic because its transmission mechanism is unknown. The cause is 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 It is now somewhat more topical, points out the researcher, 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 in the African continent it occurs 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 go about it.
It causes ulcerative skin lesions: the bacteria produce a toxin that gradually destroys the skin, it also causes anesthesia, so you don’t feel it and causes immunosuppression.
What starts as a small lump evolves into a large ulcer that can affect the bone, soft tissue as well. Although it can sometimes heal itself, 25% of patients are disabled for life due to the large scar it causes.
It is treated with antibiotics for eight weeks and ideally the wound heals daily and sometimes it is not confirmed that a person is cured until a year later. Normally this physiotherapy treatment should be accompanied, explains Cruz Mata.
The least neglected, those caused by worms
On the contrary, those that receive a little more attention despite the fact that they are also neglected are those caused by worms. The reason is because preventive treatments can be used for the population, “it is an easy tool.” It is administered during a periodicity and if a certain percentage of the population is covered, they can be 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 concerns, for example, the schistosomiasis, an acute and chronic NTD for which in 2019 at least 236.6 million people needed treatment. Less than half of them received it: 105.4 million, according to the WHO. In severe cases it can cause, among other things, 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 the neglected tropical diseases is the most serious, but Cruz Mata indicates that in terms of mortality, the one that causes the most deaths is snake bite poisoning. About 140,000 deaths a year, plus 400,000 people are disabled.
“It is not an infectious disease but it shares everything with them. It occurs 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 around the house without a flashlight; or to a job that is not in the best conditions”, explains the ISCIII researcher.
In fact, a significant group of people who suffer from snake bites are farm workers in areas between Ethiopia and Sudan. They have to harvest the crop at night because of the hellish heat it is during the day.
“They grab the cereal and cut it, the hand in that population there are many bites on the left arm basically from sticking their hand in or in the dark,” says the Spanish researcher.
The noma, may be the next
MSF’s head of Tropical Medicine 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, the majority in Latin America. It manifests with cardiac, digestive, neurological or combined alterations.
but also to or. It is not yet in the NTD group, although MSF is confident that it will be and has requested it. Treated in time it has a cure 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 at the facial tissue, explains Alcoba.
The future of neglected tropical diseases
The WHO considers that in the last decade many advances have been made in the field of NTDs, since almost 500 million people are no longer at risk. In addition, 43 countries have eliminated at least one of the pathologies.
The WHO roadmap sets the goal of eliminating at least one NTD in a hundred countries, as well as reducing the number of people requiring medical interventions by 2030.