Visceral Leishmaniasis (VL) (Black Fever or Kala Azar)

• Caused by Leishmania Donovani Parasite and harboured by an insect called the Sandfly.

• Habibpur block, barely 30 km from Bangladesh, is considered particularly vulnerable to kala-azar outbreaks.

• Kala-azar is a parasitic disease that is confined to humans, meaning that unlike, say, bird flu, there is no other animal that harbours the infection in Asia. Endemic to the Indian subcontinent in 119 districts in four countries (Bangladesh, Bhutan, India and Nepal), India itself accounts for half the global burden of the disease.

• If untreated, kala-azar can kill within two years of the onset of the ailment, though the availability of a range of drugs for almost a century has meant that less than 1 in 1,000 now succumb to the disease.

• According to numbers from the Union Health Ministry, 2016 was the first year that no kala-azar death was reported in India. Experts, however, note that like malaria and several other vector-borne diseases in India, the government only considers lab-confirmed and officially registered deaths and therefore, frequently underestimates both caseload and mortality.

• Historically, a 20-day treatment schedule with sodium stibogluconate (SSb) injection and the spraying of the malarial insecticide dichlorodiphenyltrichloroethan (DDT) in houses and surroundings were the only weapons against the disease.

• When DDT was used as part of the malaria eradication programme, very few cases of kala-azar were reported. When the use of DDT was stopped a few years later, there was an increase in the number of kala-azar cases.

• Over a period of time, resistance to the only drug (SSb injection) led to frequent outbreaks and fatalities and the Union Health Ministry, which had committed to eliminating kala-azar by 2010, revised it to 2015. Bangladesh, India and Nepal committed to eliminate the disease from the region, where elimination (as opposed to eradication) is defined as no more than one case per 10,000 population at the upazila level in Bangladesh, sub-district (block PHC) level in India and district level in Bhutan and Nepal.

• Since 2003, India’s National Vector Borne Disease Control Programme (NVBDCP) is in charge of coordinating with endemic States to eliminate the disease. With funds from a World Bank-supported project (2008-2013), the NVBDCP now funds consultants at State and district level and Kala-azar Technical Supervisors (KTS) at the State’s blocks (or clusters of village panchayats) to conduct active surveillance. That means local village health workers (Accredited Social Health Activists or ASHAs) are entrusted with constantly visiting houses and looking for patients who may present symptoms of the disease and alert health authorities.

• A rapid diagnostic test, called rK39 can — with a pinprick of blood — indicate the presence of the parasite.

• With SSb injection on the decline, there are now two mainline drugs, Miltefosine — originally conceived as an anti-cancer drug and taken orally — and Liposomal Amphotericin B (LAmB), a drug that once needed to be injected at regular intervals over four weeks but now only requires a single shot.

• These has meant that kala-azar may be on the verge of being stamped out. However the 2015 elimination target was missed and postponed to September 2017, again a deadline that won’t be met. This, in spite of the number of kala-azar patients plummeting from 36,000 in 2005 to 2,969 in 2017, according to Central government figures.

• Typical symptoms — the emaciation, anaemia and signs of a puffed spleen.

• Painless and never known to trigger the fevers and pains typical of parasitical diseases, the blemished skin is the only sign of post-kala-azar dermal leishmaniasis (PKDL).

• PKDL results from the parasites left over from a kala-azar infection that couldn’t be slain by the chemical cocktails used to treat kala-azar. Though harmless, the pigmented skin can provide harbour to the parasites and they can make their way onto other sandflies. Like the anopheles mosquito, the sandfly needs human blood to nourish their larvae and in the process can pass on parasites to new people and trigger a kala-azar infection.

• Roughly a tenth of those with a history of kala-azar will go on to develop PKDL and, potentially, seed a fresh outbreak. The precise reason for this isn’t known yet. “In the 1970s or early ’80s, VL [kala-azar] had almost disappeared and then there was suddenly an epidemic, it was later traced back to a single case of PKDL. There’s a paper on that.”

• The earliest empirical evidence for a link between PKDL as a silent agent provocateur for kala-azar outbreaks and DDT sprays came in the 1990s from C.P. Thakur, a physician and now a BJP Rajya Sabha MP. “It seems possible, that once DDT spraying stopped, the re-establishment of large sandfly populations and infection of these vectors, largely as a result of them feeding on cases of PKDL, provoked the resurgence of kala-azar”

• Even though this link between kala-azar and PKDL was hinted at since 1922, it wasn’t until 2005 that the World Health Organization (WHO) and health authorities in India, Nepal, Bangladesh, Sudan (who together account for 90% of kala-azar cases) began concerted efforts to eliminate PKDL, as part of kala-azar elimination strategies.

• The leishmaniasis parasite is an extremely resilient entity and can be dormant in the body and seed infections even after as many as five years.

Sir Ronald Ross, the India-born British Nobel Laureate who established that mosquitoes were responsible for transmitting malaria. Ross was also the one who christened the kala-azar parasite as Leishmania donovani, after the scientist duo that discovered them.

• The single injection of LAmB, which is now used to treat kala-azar, dramatically reduces the number of parasites in the blood and can cure the infection. However, when PKDL patients were subjected to the same medicine (targeting the same parasite), it didn’t completely clear the parasite load. On the other hand, prior to LAmB, the treatment of choice for kala-azar was miltefosin, which is an oral pill taken over 12 weeks. It usually brought about nausea and other discomfort because of which several patients would quit treatment midway. Miltefosin did a superior job in flushing out the parasites from PKDL patients.

• Since 2015, the urgency to eliminate PKDL, patients are being given financial incentives. All those who complete the course of treatment will get ₹2,500 (and the medicines made available through the WHO network) and the village field staff, consisting of ASHAs and KTSs, stand to get ₹500 for every such patient.

• Insecticide Synthetic Pyrethroid, the replacement for DDT. These sprays are needed at regular intervals and need a thorough application in every room including the kitchen. The problem is that the spray stinks and people say they’d rather risk kala-azar than bear with the smell, There is also a cluster effect. Families stay very close together and one infected person can spread it to the others.

• This is the disease of the poorest of the poor. Unless socio-economic conditions are improved and better sanitation is available, I don’t see just medicines and drugs completely eradicating kala-azar.


Scientists link new virus to kala-azar
 
Background:
Parasite Leishmania donovani is believed to be responsible for the dreaded infection.
People get infected when bitten by an insect called the sandfly, which harbours the disease-causing parasite.



Discovery:
Another parasite called Leptomonas seymouri may also be present.
It’s still early to pointedly blame the virus but its discovery portends a new kind of treatment regime and may aid attempts to eradicating the disease.
 
Kala-azar:
• Visceral leishmaniasis (VL), also known as kala-azar, black fever, and Dumdum fever, is the most severe form of leishmaniasis and, without proper diagnosis and treatment, is associated with high fatality.
• Caused by protozoan parasites of the Leishmania genus. migrates to the internal organs such as the liver, spleen (hence “visceral”), and bone marrow
• Signs and symptoms include fever, weight loss, fatigue, anemia, and substantial swelling of the liver and spleen.
• Kala-azar is endemic to the Indian subcontinent in 119 districts in four countries (Bangladesh, Bhutan, India and Nepal)
• This disease is the second-largest parasitic killer in the world