Amsterdam institute for Immunology and Infectious Diseases

The number of patients in the Netherlands who become infected with (cutaneous) leishmaniasis is currently limited to a few dozen patients per year. Indeed, in the absence of sand flies in our country, the vector that transmits the Leishmania parasite, it is an import disease. However, due to climate change, leishmaniasis may become endemic in the near future. "Hopefully that will stimulate the development of new treatments and vaccines", Henry de Vries, Professor of skin infections, says.

The chances of encountering a patient with cutaneous leishmaniasis in the consulting room as a general practitioner or dermatologist in the Netherlands are small, very small. "Exact figures are not available; leishmaniasis is not a notifiable infectious disease. But I estimate that at most a few dozen patients per year are diagnosed with cutaneous leishmaniasis in the Netherlands," states Henry de Vries, affiliated with the Amsterdam UMC and GGD Amsterdam. "An exception was 2005, when about 200 soldiers deployed to Afghanistan were infected and also developed disease symptoms."

"The WHO recently declared leishmaniasis as skin Neglected Tropical Disease to increase
attention and interest in this disease."

Henry de Vries

Dermatologist and Professor of skin infections

Sandfly

A brief explanation: Leishmaniasis is caused by the single-celled parasite Leishmania, of which more than twenty different species are known to be infectious to humans. Infection occurs by a sting from an infected female sand fly. Leishmaniasis is endemic in about 100 countries, particularly in South America, Mediterranean countries, the Middle East, India, and Bangladesh. It is estimated that the global incidence of leishmaniasis is 12 million per year.

Winterizing

"The infections detected in the Netherlands are usually contracted while on vacation, wintering or staying for work in one of the endemic areas. In addition, the disease is sometimes seen in asylum seekers and migrants from endemic countries," Prof. De Vries says. "The cutaneous form, which can be caused by different species, manifests itself in a non-healing wound. For many patients, this is also the reason to report to the general practitioner. The general practitioner will usually first think of a bacterial infection and prescribe antibiotics. If these are unsuccessful, a referral to a dermatologist usually follows. Pathological examination of a biopsy - together with the patient's travel history - will then quickly provide clarity. Ideally, the dermatologist then refers the patient to the dermatology department at one of the two tertiary centers for leishmaniasis: Amsterdam UMC and Erasmus MC. After all, treatment requires expertise and experience."

Limited options

"Cutaneous leishmaniasis is in principle self-limiting. However, that process can take a long time and is accompanied by scarring and loss of function; reason why active treatment is usually chosen" Prof. De Vries says. The problem, however, is that there are few drug options. Prof. De Vries: "Leishmaniasis is a disease for which there is hardly any interest from the pharmaceutical industry. This is because the endemic countries are for the most part countries with few financial resources. The WHO therefore recently declared leishmaniasis a skin Neglected Tropical Disease, or skin NTD for short, with the aim of increasing attention and interest in this disease. Currently, cutaneous leishmaniasis can be treated locally with cryotherapy, heat therapy or injections of five-valent antimony compounds or amphotericin B. Treatments that have been around for 50 years and cause many side effects. Systemic treatment with antimony and amphotericin B even requires 3 weeks of hospitalization. A relatively new and oral agent is the oncolytic drug miltefosine, an agent that can kill some Leishmaniasis species. The side effects of miltefosine are much more favorable."

PCR and LAMP

Recently, Prof. De Vries and Dr. Schallig published a review article on the current state of leishmaniasis diagnosis and treatment. "That was, at the request of the respective journal, an update of an earlier review performed in 2015. Unfortunately, due to lack of interest from both the pharmaceutical industry and research funding agencies, there was little progress to report in treatment options. However, there have been improvements in diagnostics, such as the arrival of PCR to find out which species is involved. A simplified version of this, called LAMP, is also applicable in countries with less well-equipped laboratories."

Endemic in the Netherlands

As mentioned, leishmaniasis is an import disease in the Netherlands. After all, the vector necessary for transmission, the sand fly, does not occur in the Netherlands. Does not occur yet, we should actually say. Prof. De Vries: "As a result of climate change, the distribution area of the sand fly is shifting. They have already been observed around Paris. So it is no exaggeration to assume that in ten or twenty years leishmaniasis could also be an endemic disease in the Netherlands."

If leishmaniasis becomes endemic in the "rich" West, interest in the disease is likely to increase and lead to more attention (and money) for developing better treatments. "In addition to new effective drugs with far fewer side effects, this could also lead to the development of vaccines, for example. The technique of mRNA-based vaccines has recently shown to be a game changer."

For more information contact Prof. Henry de Vries of read the scientific article here.

Source: read the original (Dutch) article by Marten Dooper on the DOQ website here.