You may have read about the soaring number of dengue cases along with Covid-19, but leishmaniasis could emerge as another public health problem if not addressed promptly.
Leishmaniasis is a vector-borne – and neglected – tropical disease caused by a Leishmania protozoan parasite transmitted by the bite of an infected female sandfly. It is currently prevalent in 98 countries, including Pakistan. Leishmaniasis is known by a myriad of popular names: Aleppo boil, Aleppo button, Delhi boil, Kandahar sore, Lahore sore, Oriental sore, black fever, and Kala-azar are more common.
Leishmaniasis comprises three clinical forms, recognised as cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), and visceral leishmaniasis (VL) form. Cutaneous leishmaniasis is the most widespread form of leishmaniasis. It is recognised as the ninth most prevalent infectious skin disease worldwide.
According to the World Health Organization (WHO), leishmaniasis is associated with malnutrition, population displacement, inadequate housing, a weakened immune system, and poverty. About 12 million people worldwide suffer from CL, and every year about 0.5 million to 2 million new cases are identified.
Devastating epidemics of the CL have been described from all provinces of Pakistan. To date, about 21,000 to 35,000 CL cases are reported from northern, southern and western areas. Though the cutaneous form of leishmaniasis dominant in the country is not life-threatening and remains subclinical, sometimes initially a papule is formed that enlarges and ulcerates. The size of ulcer-like lesions varies from 0.5 cm to 3 cm in diameter. The lesions usually appear on legs, feet, arms, hands, face, and neck. Secondary bacterial infection is common, which turns painless lesions into painful lesions. Most lesions heal over months, leaving behind a permanent scar affecting patients cosmetically and psychosocially. That can lead to severe social stigmatization; people with scars are victimised and excluded from public life.
Various species of sandflies act as vectors of leishmaniasis in tropical and sub-tropical countries. These tiny flies live in dark, damp places and do not fly high or far. They have a range of only 50 meters from their breeding site. Sandflies become infected by feeding on infected animals. An infected sand fly can transmit the parasite to both humans and animals for the rest of its life. Unlike mosquitoes, they fly silently, and their small size (2-3 mm) allows them to penetrate through mosquito nets. They are most active in the evening and at night. Because of its diminutive size, activeness in the dark, silent flight, and painless bite allows the sand fly to go undetected.
Identification of the species, especially in CL, can be helpful for treatment and clinical care. At present, there is no single reference test for CL diagnosis. Observation of Leishmania parasites in a clinical specimen is the most commonly used diagnosis method in underdeveloped countries. The clinical perspectives and responses to treatment efficacy also vary according to Leishmania species.
Leishmaniasis is a poverty-related disease, and many people cannot access medical treatment because it is too expensive. The reason treatment is costly in Pakistan is that the country lacks local production of Meglumine antimoniate. Most government hospitals in affected areas have limited stock of the drug of choice, leaving it to people to buy it themselves.
The health authorities have reported CL cases since November 2018, most of them from the merged districts previously known as the Federally Administered Tribal Areas, close to the border with Afghanistan. A recent upsurge in South Waziristan is showing the seriousness of the situation. Due to the prevailing uncertainty in leishmaniasis endemic bordering Afghanistan, the possible relocation of Afghans to Pakistan could spiral the situation out of control. In addition, this year’s monsoon rains and favorable climate provide the best environment for sandflies to thrive. These specific circumstances and suitable weather conditions can spread the disease and sandflies to areas that are now protected.
Given all this, the relevant authorities need to plan to avoid any grave damage. A Glucantime injection (Meglumine antimoniate) is the sole option for CL patients in Pakistan. There is no domestic production of the injection, so the health authorities rely on imports by international organisations such as WHO and Médecins Sans Frontières (MSF). Provincial governments should start efforts and coordinate with these organisations to obtain maximum doses of this injection.
Vector control actions should commence with no delay. Indoor residual spraying and environmental activities are needed in the affected areas. Distribute free long-lasting insecticidal bed nets and encourage people to use them. The incubation time of this disease is long, meaning that the interval between the entry of the parasite in the patient and the onset of symptoms is longer. Once patients appear, these measures remain useless. There is a strong possibility that, by that time, sandflies have spread the disease on a large scale. So, carry out control measures now, maintain Meglumine antimoniate injection stock, and educate the community.
In July 2020, in a newspaper article ‘Dengue forthcoming, Covid-19 concentrated upon’, I warned of the potential danger of a dengue outbreak in the year to come. But unfortunately, Covid-19 consumed all the attention and resources, while dengue reports started coming from all the provinces. The same can happen for leishmaniasis. If the authorities delay the implementation of these precautions, the country could likely face a severe outbreak of CL early next year.
The writer is a post-doctoral fellow at the Faculty of
Veterinary Medicine, Universiti Malaysia Kelantan (UMK), Malaysia.
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