Question

1.1 Leishmaniasis is a vector-transmitted protozoal complex disease caused by variety of Leishmania species:

Write explationary notes on how this disease is transmitted to both animals and humans.In your answer include aspects such as clinical, diagnosis ,management and control.

Question 4

After. reportedly swimming in a stream infested with snails breeding sites,several teenage boys visted a local clinic presenting with fever,abdominal discomfort and blood in their urine:

4.1 Suggest the possible etiological agent and provide a detailed life cycle of the parasite.

4.2 What management and control measures shouls the clinician advise the community to take to prevent further spread of the disease.

Answer 1

Answer 1.1)

Life Cycle:-

Host: Leishmania completes its life cycle in
two hosts:
1. Vertebrate host (man, dog, rodents, etc.)
2. Insect vector (female sandfly): Phleboto-
mus argentipes.
Infective form: Promastigote forms present
in the midgut (majority) or foregut (small
proportion) of female sandfly.
Mode of transmission: By bite of an infected
sandfly mainly during the late evening or the
night time. Minimum 10–1,000 promastigotes
per infective bite are required to initiate the
infection.
In vertebrate hosts, including humans:
Promastigotes are regurgitated from the
midgut rarely or directly discharged from
foregut (proboscis) of the female sandfly
into the skin of the vertebrate host
Promastigotes are phagocytosed by the
skin macrophages and transform into
amastigote forms within 12–24 hours.
The amastigote forms inside the macrop-
hages multiply further causing cell rupture
and release into the circulation.
Amastigotes are carried out in the circulation
to various organs like liver, spleen and bone
marrow and invade the reticuloendothelial
cells like macrophages, endothelial cells, etc.
In sandfly:
During the blood meal taken up by the
sandfly, the amastigotes are ingested and
transformed into promastigote forms in the
insect midgut.
Promastigotes multiply by longitudinal
fission and pass through various stages
such as:
Amastigote → procyclic promastigote
→ nectomonad promastigote → hapto-
monad promastigote → leptomonad
promastigote → metacyclic promastigote.
The metacyclic promastigotes multiply
in the midgut of vector by binary fission
and a small proportion migrates to the
foregut (proboscis). They infect a new
host during another blood meal.
The duration of the life cycle in sandfly varies
from 4 to 18 days depending on the species.
Pathogenicity:-
Various factors contribute to the pathogenesis
such as:
The phagocytosis of the promastigotes is
facilitated by binding of the promastigote surface
antigens such as 63 kDa glycoprotein (gp-63) and lipophosphoglycan (LPG) to complement

receptors (CR3 and Cq1) on macrophages.
The gp-63 antigen also gives protection
from proteolytic enzymes secreted from the
phagolysosome.
LPG is the principle virulence factor, exhibits
variety of functions. It prevents phago-
some maturation and protects the parasite
against hydrolytic enzymes secreted from
the phagolysosome.
The amastigotes multiply within acidic
parasitophorous vacuoles.
Glycosyl phosphatidyl inositols (GPIs) is a
major surface protein on amastigotes, helps
in protecting from phagolysosomal attack
inside the macrophage.
Host Immune Response:-
Depending on the host immune response,
the amastigotes are either killed or allowed to
multiply inside the macrophages.
Like leprosy, the immunology of leishmania-
sis is complex and bipolar. It has two extreme
poles, each which is characterized by one of
the two type of T helper subset responses, i.e.
T helper 1 or T helper 2 responses.

Clinical features:-

Incubation period ranges from 2–6 months.
The hallmark of VL is a triad of fever, hepato-
splenomegaly and pancytopenia.
Fever: The most common symptom of
VL is an abrupt onset of moderate to high
grade fever associated with rigor and chills.
Typically it is described as double rise of
fever in 24 hours.
Splenomegaly: It is the most consistent
sign. The spleen may become hugely
enlarged and palpable below the umbilicus.
Hepatomegaly (usually moderate in degree)
soon follows splenomegaly.
Lymphadenopathy: Common in most of
the African endemic regions (rare in Indian
subcontinent).
Hyperpigmentation: Mostly seen in brown-
skinned individuals from Indian subcontinent.
Pedal edema and ascites: Occur due to
hypoalbuminemia, may be seen in advanced
illness.
Mucosal lesions in mouth and nasopharynx-
Hematological abnormalities (bone
marrow dysfunction):
Anemia (normocytic and normochro-
mic): Appears early and may become
severe enough to cause congestive heart
failure
Leucopenia

Thrombocytopenia:Can lead to epistaxis,
retinal hemorrhages, and gastrointestinal
bleeding
Hypergammaglobulinemia (due to
polyclonal B cell activation)
Leishmanoma: Nodular skin lesions seen
in African cases only.
Weight loss (cachexia)
Secondary infections: Such as measles,
pneumonia, tuberculosis, bacillary or
amoebic dysentery and gastroenteritis are
common.

Diagnosis:-

Microscopy
Demonstration of amastigotes inside the
macro phages (also known as Leishman
Donovan bodies or LD bodies) is the gold
standard method for the diagnosis of VL. Smears should be stained with
Leishman, Giemsa or Wright stains. Th e
various samples include:
Splenic aspiration: The sensitivity of
splenic smear examination is excellent (>
95%) but splenic puncture is associated with
risk of hemorrhage. Grading of LD bodies
from splenic smear is useful in determining
the parasitic load and monitoring the
response to treatment.
Bone marrow aspiration: Iliac crest
aspirate is the most commonly preferred
sample though the sensitivity is around 60–
85%. If bone marrow fi ndings are negative
but the clinical suspicion is strong, then the
splenic aspiration is indicated
Lymph node aspiration: It is useful only in
African cases of kala-azar and sensitivity is
low (50%).
Liver biopsy: Less sensitive and carries the
risk of hemorrhage
Peripheral blood smear: Amastigotes
within mononuclear cells and neutro-
phils can be seen in a stained blood smear.

Sensitivity increases by making thick smears,
using centrifuged blood and making smears
from buffy coat particularly in HIV patients
Biopsy specimens of various organs: Like
oropharynx, stomach, or intestine. This
is particularly important in patients with
AIDS.
Culture
Sample: Aspirations from spleen, bone
marrow or other tissue and also buffy coat.
Medium:
NNN medium :Novy-
MacNeal-Nicolle (NNN) medium is a
biphasic medium, composed of
Schneider’s Liquid medium: It contains Schneider’s Drosophila insect
medium supplemented with 30% fetal
calf serum. It is found to be more sensi-
tive than NNN media.
Semisynthetic fetal calf serum free
medium.
Microculture method using micro-
capillary tubes.
Inoculated specimens are incubated at
ambient temperature (22–26°C) upto 4 weeks
Amastigotes transform into promastigotes
in the culture fluid which are detected by
staining with Giemsa stain.
Culture fluid is examined for twice a week
for first 2 weeks and once a week thereafter
for up to 4 weeks; before they are reported
as negative.

Management:-

Supportive therapy
Correction of pancytopenia should be done by
blood transfusion. Similarly, other associated
conditions should be managed promptly.
Specific antileishmanial drugs
Pentavalent antimonial
It is the drug of choice in most endemic
regions of the world, except in Bihar (due to
emergence of drug resistance).
Two pentavalent antimonial (SbV) prepara-
tions are available:
Sodium stibogluconate (100 mg of SbV/
mL)
Meglumine antimoniate (85 mg of SbV/
mL)
WHO recommendations
For VL, the daily dose is 20 mg/kg by rapid
intra venous (IV) infusion or intramuscular
(IM) injection, and therapy continues for
28–30 days till smear microscopy is
negative.
For CL, 1–3 ml of antimonial prepara tions
should be infi ltrated at the base of the
lesions for two to three times at interval
of 1–2days.
Resistance to antimonials
Increased resistance has been reported
to L. tropica, L. major and L. mexicana in
comparison to L. donovani.
L. donovani: Resistance is only reported
from North Bihar. Mishandling of anti-
leishmanial drugs is the single most
important contributor to the development
of drug resistance.
Mechanisms: Occurs due to failure of
reduc tion of SbV (prodrug) to its active
form SbIII inside the resistant L. dono vani
amastigotes.
Amphotericin B
It is currently used as a fi rst-line drug in
Bihar for the treatment of VL. In other
parts of the world, it is used when initial
antimonial treatment fails
Treatment Old World Leishmaniasis. It is also the drug of choice for the New world
mucocutaneous leishmaniasis (MCL)
Conventional amphotericin B deoxycholate
is administered in doses of 0.75–1.0 mg/kg
on alternate days for a total of 15 infusions
Alternatively the lipid formulations of AmB
are used which have lower side eff ects
Paromomycin
It is an aminoglycoside antibiotic with anti-
leishmanial activity. It is given IM at a dose of 11
mg of base/kg daily for 21 days
Miltefosine
It is the fi rst oral compound approved for the
treatment of leishmaniasis. It is given as daily
dose of 50 mg once or twice for 28 days.

control Measures
Vector control measures to eradicate sandfly:
Personal prophylaxis by using insect repel-
lents or bed nets.
Control of canine or rodent reservoir
Phlebotomus doesn’t fly high above the
ground level and it is nocturnal in habitat.
So, sleeping at top fl oors also can prevent
transmission.
Early treatment of all cases (mainly anthro-
ponotic VL and PKDL cases).

Answer 4:-

The possible etiologic agent is Schistosoma haematobium.

4.1:- Life cycle :-

Schistosoma eggs are eliminated with feces or urine, depending on species . Under appropriate conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tails, becoming schistosomulae . The schistosomulae migrate via venous circulation to lungs, then to the heart, and then develop in the liver, exiting the liver via the portal vein system when mature, . Male and female adult worms copulate and reside in the mesenteric venules, the location of which varies by species (with some exceptions).

4.2:-

Management and Control Measures:-

Treatment of Schistosoma haematobium

Praziquantel is the drug of choice for the
treatment of schistosomiasis.

Preventive measures include:
Proper disposal of human excreta and urine.
Eradication of snails by using molluscicides
such as metal salts (iron or aluminium
sulfate), metaldehyde, methiocarb and
acetylcholine esterase inhibitors.
Treatment of infected persons.