KALA AZAR - SCIENCE AND TECHNOLOGY
News: IACS’s
novel compound treats drug-resistant kala-azar infection
What's in the news?
● The
highlight of the work carried out by researchers at the Kolkata-based Indian
Association for the Cultivation of Science (IACS) is the potential of the quinoline
derivatives to treat drug-resistant leishmaniasis, also called kala-azar (black
fever).
Key takeaways:
● The
quinoline derivative is a potent
inhibitor of an enzyme called topoisomerase
1 (LdTop1), which is essential for maintenance of DNA architecture in the
parasites; this enzyme is distinct from the one found in humans.
● Poisoning
of LdTop1 imparts a significant level of cytotoxicity to both the Leishmania
parasites found in gut of sandfly vectors (promastigotes) as well as the form
found in the infected humans (amastigotes) of both the wild type and the
antimony-resistant isolates without inducing any lethality to human and mice
host cells.
Kala Azar:
● Kala-azar
or Visceral Leishmanias is a vector
borne (sandfly) neglected tropical disease caused by the protozoan parasites of
the genus leishmania that afflicts the world’s poorest populations in over
90 countries throughout Asia, Africa, the Middle East, and Central and South
America.
● Sandflies
are brown in colour and have hairs on their bodies. The flies are infected with
the parasite called ‘leishmania donovani’.
● The
vector sandfly is known to live in cracks and crevices of muddy houses,
especially in dark and humid corners. According to the WHO, there are 3 main
forms of leishmaniases of which kala-azar is the most serious form.
● The
disease affects some of the poorest
people and is linked to malnutrition, population displacement, poor
housing, a weak immune system and a lack of financial resources.
● Leishmaniasis
is also linked to environmental changes
such as deforestation, and urbanization, according to WHO.
Affected Population:
● Current
annual estimates of kala-azar are about 1,00,000, with more than 95% of cases
reported to the World Health Organization (WHO) from India and other tropical
countries, most importantly co-infection with HIV, which leads to an
immunocompromised state.
● The
four States endemic for kala-azar in India are: Bihar (33 districts), Jharkhand (4 districts), West Bengal (11
districts), and Uttar Pradesh (six districts).
Symptoms:
● Irregular
bouts of fever over many days, weight loss, enlargement of the spleen and
liver, and anemia are known symptoms.
● The
skin may become dry, thin and scaly in patches and hair may be lost.
● In
people with a light skin tone, greyish discoloration of the skin of hands,
feet, abdomen and face may be seen, that is why the disease is also called
“Black fever".
Treatment:
● Leishmaniasis is a
treatable and curable disease, which requires an
immunocompetent system and thus those having a weak immune system are prone to
get severely affected. All patients diagnosed require prompt and complete
treatment.
● Anti-leishmanial
medicines are available for treatment.
● Vector control is also
recommended by the WHO, which means reducing or
interrupting the transmission of disease by decreasing the number of sandflies
in surroundings through insecticide spray, use of insecticide-treated nets,
etc.
Indian government response:
● Overcoming
drug resistance in clinical leishmaniasis is a severe challenge in rural India.
The current treatment regimens against kala-azar use formulations that are
toxic and induce high levels of drug-resistance.
● The
government aimed to eliminate the disease in India by 2015, but that deadline was missed.
● However,
the number of cases has been brought down significantly through the National Kala-Azar Elimination Programme.
● Medicines,
insecticides and technical support were given by the central government, while
state governments provided for costs involved in implementation.
● The
program was implemented through State/District Malaria Control Offices and the
primary health care systems.