Skip to 0 minutes and 12 secondsMITALI CHATTERJEE: So cases of visceral leishmaniasis, along with cases of post kala-azar dermal leishmaniasis, are suspected to be carriers of this disease. And more importantly, visceral leishmaniasis presents with features of fever and enlargement of the liver and spleen. But often, in about 10% of these individuals, they may develop a dermal sequel to the disease, which is called post kala-azar dermal leishmaniasis, or PKDL, as it is known. So essentially, it was identified in this city by Sir UN Brahmachari, who observed that individuals who had visceral leishmaniasis were a few years later coming with unusual dermal lesions, which ranged from small areas of hyperpigmented patches to areas that were slightly raised. There were little nodules which were appearing.
Skip to 1 minute and 10 secondsSo he called them post kala-azar dermal leishmanoid. So it is supposed to be a sequel to VL, but not necessarily. It may also occur independently. Around 10% of VL cases can develop PKDL. It still remains a million-dollar question as to which individual will move from VL to PKDL. We still do not understand what are the predisposing factors for why should a patient of VL develop PKDL. These PKDL cases then become the disease reservoir, which then again will manifest in an epidemic of VL. So it's a cyclical pattern that VL follows, where the episode of PKDL kind of follows after an epidemic of VL. So that's why we have cyclical appearances of epidemics of VL which are recurring.
Skip to 2 minutes and 7 secondsNILAY KANTI DAS: Diagnosis of PKDL is of paramount importance, because it's a disease which does not cause much of a symptom. When a person comes to us, we have to have very high index of suspicion that we are dealing with PKDL. The first important thing is we ask for a history of visceral leishmaniasis or history of kala-azar. Then, if you find that it is present, then we look for the typical skin lesion, like presence of lumps and bumps or presence of patches. There are certain clinical clues. One important such clue is presence of photosensitivity, the phenomena is when the person goes out to sun, their skin becomes extremely red.
Skip to 2 minutes and 56 secondsApart from that, the person can have some nodules, some bumps on the lips and sometimes on the tongue. Even the genitals may be involved. So those things are not really seen in leprosy, which can help in differentiating. And also, we have to depend on the laboratory diagnosis. After the clinical diagnosis is made, we rely on the slit-skin smear. In the programme of kala-azar elimination programme that's running in India, we have got the rK-39 strip test. That is an antibody dependent diagnostic method and can be utilised for field purposes. So apart from having a strip test, which can sometimes be misleading, and there can be cases of misdiagnosis, we have got other methods where we can detect parasite DNA.
Skip to 3 minutes and 52 secondsBut this parasite DNA detection cannot be applied to the field. So the field worker, if they are in a dilemma, can take a sample and send it to the reference laboratory, where the parasite detection can be done by PCR. So treatment of PKDL has evolved over time from sodium stibogluconate, which we used to give maybe a decade back-- has gone into oblivion because of the resistance that we have observed over time. Government of India has taken cognizance of the fact and has started miltefosine as the first-line drug in the treatment of PKDL. But it has been observed that some cases are not responding to miltefosine, even. So we have brought in amphotericin B for the treatment of PKDL.
Diagnosis & treatment of PKDL
In this step, we visit a South Asian (Indian) perspective on the diagnosis and treatment of post- kala azar dermal leishmaniasis (PKDL) with two experts in the disease: Professor (Dr) Mitali Chatterjee from the Post-Graduate Medical Institute and Professor (Dr) Nilay Kanti Das from the Bankura Sammilani Medical College.
PKDL lesions usually first appear around the mouth and chin. The presence of Leishmania donovani parasites is confirmed by parasitological diagnosis, usually by examining skin slit material under a microscope. Particularly when lesions develop with 12 months of a primary VL infection, it is important to diagnose PKDL parasitologically, as circulating antibodies can confound an rK39 test.
Remember that the presentations of PKDL in the Indian Sub-continent and East Africa are similar. However there are differences in the conditions under which symptoms may develop (e.g. length of time after a VL infection) and in the total numbers of PKDL patients per region. In general, a higher percentage of VL patients develop PKDL in East Africa in a shorter time period than in South Asia .
PKDL patients are hard to treat and the recommended drugs are sodium stibogluconate (East Africa) and/or AmBisome (South Asia). It is also considered important to treat PKDL patients as they are a possible reservoir of infection – a key factor in an elimination context.
© London School of Hygiene and Tropical Medicine 2018