Challenges in Leishmania control

Dr Nimal D Kasturiaratchi

Leishmania is a communicable disease and comes under the category the Neglected Tropical Diseases (NTDs). The first patient with Leishmania was diagnosed by eminent dermatologist Dr D N Atukorala in 1992. The interests of people aroused by the social marketing campaign of the leprosy campaign made more people to come to dermatology clinics with skin patches and that made the diagnosis of Leishmania also possible

During the last three to four years, about 600 cases in the Anuradhapura district and about 700 cases in the Matara district have been diagnosed and treated. However new patients continue to appear and seek treatment at dermatology units. In a field clinic that was conducted at Padaviya, Anuradhapura recently consultant dermatologist Dr Hulangamuwa diagnosed 13 cases of Leishmania that included four schoolchildren and a teacher from the Padaviya School.

In the North Central Province there are endemic locations such as Padaviya, Sripura and Thalawa, while in the Southern province Lesihmanis is found in coastal areas such as Kudawella. In Polonnaruwa too, for this year, about 25 patients have been detected.

It has not even spared government officers and those who got affected include PHIs, midwives and Ranaviruvos.

It appears as skin diseases with a non-itching, painless raised dot in the skin which gets bigger and may lead into a small wound. Some of the lesions are self-healing. Since the lesions are painless and small at the beginning most people ignore them and that makes their arrival at a treatment centre delayed.

According to medical literature it is a disease spread by sand fly and is known as a zoonosis meaning humans get it from animals. The parasite is expected to be harboured in an animal (domestic or wild) and the sand fly transmits the disease to humans as they bite them.

The skin lesion is usually found at the site of insect bite and therefore mostly concentrated to the exposed parts of the body. It has been shown that most commonly lesions are seen in the face and in the hands.

The sand fly bite is believed to occur from dawn to dusk. But the Sri Lankan experience shows otherwise and indicates that people are bitten by this disease-carrying insect even during day. The lifecycle of the Leishmania parasite has a biological phase within the body of the sand fly and that has to be completed for the disease to be transmitted to a human. The Sinhala name for the sand fly is either velimessa or hohaputuwa.

Leishmania has two manifestations. One as a skin lesion and this type is called the cutaneous type. However there is a more dangerous type called the visceral type that affects that makes the liver and spleen to enlarge.

This type of illness may have fatal consequences and is popularly known as Kala Azar (‘dark liver’). Kala Azar is found in India (in Bihar where most of the Buddhist pilgrim sites are located) and in Nepal. The Kala Azar found in India and Nepal is caused by the same type of parasite found in Sri Lanka called Donovani Mon 37 . Since its first diagnosis, some 18 years ago, two patients with Kala Azar have been diagnosed in Sri Lanka.

Interventions

Lesion in the face	Parasite under microscope

Preventing the spread of the disease can be undertaken by minimizing the people for insect bites. However this is not an easy task. Bed nets, insect repellents, insecticide spraying and cleaning the household surroundings are some of the measures that can be adopted. Further finding the host animal on which the sand flies feed on is also an important aspect of a prevention program.

However early diagnosis and treatment of patients exposed to this disease will also help to minimize the risk of human to human transfer of the disease and the development of complications of the skin lesions. The skin lesions are treated with injections to the site and also by clinical burning with liquid nitrogen.

The present experience shows that suspected patients turn up for treatment rather late. A rough estimate is about four-six months after observing the skin lesion by an individual for the first time. The treatment centers are the dermatology units located in government hospitals and patients may be required to come seven or eight times to such a clinic for injections and cryotherapy (burning).

A patient in Padaviya loses about one thousand rupees in each visit in coming to Anuradhapura Hospital for treatment. Approximately, it cost about ten thousand rupees if they visit Anuradhapura eight times for treatment. Poor, who do not have such money, may therefore stay away from treatment. Carrying out field clinics by qualified medical teams will immensely help these marginalized people to access treatment.

The unknowns and research

There are many unknowns with regard to Leishmania in Sri Lanka. The primary host is unknown. It could well be domestic animals such as dogs, cattle, cats or wild animals such as monkeys, rats, birds. Researchers have found the parasite among a very small sample of domestic dogs. But they have not demonstrated the parasite within the bodies of sand fly in Sri Lanka.

It is not yet confirmed that it is the sand fly that is transmitting the disease in Sri Lanka as attempts to catch the sand fly in the household of patients have failed.

There is room for more research to be undertaken by the universities and research institutes. At present the Medical Faculties at Colombo and Peradeniya are involved in some studies and the Parasitology Department at the Rajaratara Medical Faculty is teaming up with the Regional Director of Health Services at Anuradhapura to facilitate the control of the disease. A similar effort has been initiated at Matara with the assistance of Galle Medical Faculty researchers.

The transmission from man to man has not been proven but in Sri Lanka there are instances where more than one member of the family is affected which could be due to separate insect bites.

There are many challenges in the control of Leishmania. In the absence of scientific knowledge it will be very difficult to control the disease-carrying vector (insect) or the primary host (animal). This leaves us with fewer options. Early diagnosis and treatment will ensure less suffering to people and prevent the possible complications.

Although field clinics sounds like a good approach, there are difficulties in drawing upon the human resources from the busy dermatology units in bigger hospitals.

Similarly both cryotherapy and injections with sodium stibogluconate are expensive. A vial of 100 mls of stibogluconate costs Rs 18,000.

Sodium Stibogluconate is not a registered drug in Sri Lanka and the importers have to make special arrangements with the government to import the drug.

Availability of liquid nitrogen and equipment for cryotherapy are not easily available in the government sector.

Fairmed Foundation is assisting the health staff in Anuradhapura, Polonnaruwa and Matara in easing some of these constraints. But more can be done if more attention is received for this health condition

Danger

Are we posed with a danger? Yes, the present cutaneous can lead into much more dangerous and costly to manage visceral form with the appearance of a mutant (genetically modification) of the parasite.

Further it is not known clearly how the cutaneous type can become a visceral type. But now we have evidence of visceral form already appearing in Sri Lanka and it is widespread and common in India, Nepal and Bangladesh.

It could be tomorrow, or within years that we may have a major health problem in our country and we urge everyone to be aware of this and to contribute to avert this danger.

The writer is a Medical Social Scientist, Sri Lanka Representative, Fairmed Foundation