Transcript Environmental Determinants of Leishmaniasis in Syria

Cutaneous
leishmaniasis in Syria
Leishmaniasis
Introduction
Infectious disease caused by intracellular
protozoan parasites of the genus
Leishmania
visceral, cutaneous, and mucocutaneous
Visceral Leishmaniasis
Known as kala azar
Characterized by
chronic recurrent fever
splenomegaly
pancytopenia
weight loss
high mortality
Cutaneous leishmaniasis (CL)
most abundant
CL is caused by at least 12 different
species of Leishmania, and each of
them has its own characteristic, vectors,
and reservoirs
(CL) Presentation
Single or multiple chronic skin ulcers
Destructive mucocutaneous lesions, or
Disseminated infection
Mode of
Transmission
At least 70 different
species of sandflies,
small insects of the
genus Phlebotomus
The primary sandfly
vectors of the
Southwestern Asia
region include
Phlebotomus
papatasi
Phlebotomus sergenti
CL Occurrence
CL is found in most countries of the
tropical and subtropical regions of the
world
90% of all cases occur in only six
countries: Afghanistan, Brazil, Iran, Peru,
Saudi Arabia, and Syria
CL Incidence
Incidence fluctuates due to:
new agricultural projects
weather variability
changes in reservoir densities, and
annual sandfly patterns
CL Incidence
The annual incidence of CL throughout
the world is 1 to 1.5 million cases with
350 million people at risk of getting the
disease, only 300,000 cases are
officially reported
Most Important Infectious Agents
Old World:
Leishmania major
Leishmania tropica
Leishmania aethiopica
New World:
Leishmania braziliensis
Leishmania mexicana
Leishmania major
Also known as the rural type
Causes moist cutaneous lesions
Occurs in southern districts of Syria
Reservoir host is the rodent
Psammomys obesus (Fat Sand Rat)
Spreads zoonotically from desert
rodents to man by sand fly
Phlebotomus papatasi
Leishmania major
Incubation period is week to months
Ulcers appear on the extremities
Spontaneous healing occurs within 3 to 6
months, leaving a depigmented pitted
scar
Leishmania major
Mode of Transmission
Rodent
Sandfly
Human
Leishmania major
Occurrence
Semi-arid climates
hot dry season lasting 6 or more months
temperature exceeding 35-40oC
Rainfalls vary from 100mm- 600mm
annually.
Found in low-lying desert regions
Soils are deep and friable but
sufficiently cohesive for the
construction of deep, durable, rodent
burrows
Leishmania tropica
Known as urban CL, or “anthroponotic
CL”
Causes dry lesion
Transmitted from person-to-person
Humans and the domestic dogs serve as
the reservoirs of infection
Causative parasite in northern districts
Transmitted by the sandfly Plebotomus
sergenti
Leishmania tropica
Occurrence
Spreads in areas of
urban centers
higher altitudes
temperate climate
arid, cold and warm weather
Leishmania tropica
Incubation period 2 months > a year
Lesion is usually facial and begins as a
pruritic, purplish nodule (the Aleppo
button) then slowly enlarges and finally
breaks down after 3 or 4 months
Healing of the ulcers may require a year
or more
Leishmania tropica
Mode of Transmission
Sandfly
Human
Climate in Syria
Two seasons:
dry and hot summer (July hottest month)
wet and cold winter (January coldest month)
spring and fall mild with some rainfall
Temperature declines from south to north
(average annual temperature is 19.7oC in
the south,and 17.2o in the north)
The average annual precipitation is
100mm-1500mm
Purpose of the Study
To describe temporal and spatial
patterns of disease and to characterize
risk factors for exposure.
CL Case Data Used in the Study
Location
All of Syria
Damascus Suburbs, Aleppo
Type of data
Summary Count
Summary Count
Time Period
1990-1997
1994-1997
Frequency
Monthly
Monthly
Spatial Units
14 Districts
1,824 Villages
No. of Cases
112,484
32,076
Preliminary Results
18000
16000
14000
No. Cases
12000
10000
8000
6000
4000
2000
0
1990
1991
1992
1993
1994
Year
1995
1996
1997
Incidence Rate per 1000 in each
district between 1990-1997
4.00
3.50
3.00
Damas City IR
Damas Sub IR
Daraa IR
Suweida IR
IR/1000
2.50
Qunaitra IR
Homs IR
Hama IR
2.00
Aleppo IR
Idleb IR
Lattakia IR
1.50
Tartous IR
DeirAlZor IR
Rakka IR
1.00
Hasakeh IR
0.50
0.00
1990
1991
1992
1993
1994
Years
1995
1996
1997
IR/1000 in Damascus Suburbs
b/w 1994-1997 according to sex
3.50
Total IR
Male IR
3.00
Female IR
IR/1000
2.50
2.00
1.50
1.00
0.50
0.00
1994
1995
1996
Years
1997
IR/1000 in Aleppo b/w 1994-1997
according to sex
3.50
Total IR
Male IR
3.00
Female IR
IR/1000
2.50
2.00
1.50
1.00
0.50
0.00
1994
1995
1996
Year
1997
IR/100 in Damascus Suburbs b/w
1994-1997 according to age groups
6.00
IR<1 yr
IR1-4 yr
IR5-14 yr
IR15+ yr
5.00
IR/1000
4.00
3.00
2.00
1.00
0.00
1994
1995
1996
Years
1997
IR/100 in Aleppo b/w 1994-1997
according to age groups
6.00
IR <1yr
IR 1-4yrs
5.00
IR 5-14yrs
IR 15+yrs
IR/1000
4.00
3.00
2.00
1.00
0.00
1994
1995
1996
Year
1997
Damascus Suburbs
Total Incidence Rates
0.45
TInc94
0.40
TInc95
0.35
TInc96
TInc97
IR/1000
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
Months
Aug
Sept
Oct
Nov
Dec
Damascus Suburbs
Male Incidence Rates
0.45
MInc94
0.40
MInc95
0.35
MInc96
MInc97
IR/1000
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
Months
Aug
Sept
Oct
Nov
Dec
Damascus Suburbs
Female Incidence Rates
0.45
FInc94
0.40
FInc95
0.35
FInc96
FInc97
IR/1000
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
Months
Aug
Sept
Oct
Nov
Dec
Aleppo
Total Incidence Rates
0.40
TInc94
TInc95
0.35
TInc96
0.30
TInc97
IR/1000
0.25
0.20
0.15
0.10
0.05
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
M onths
Aug
Sept
Oct
Nov
Dec
Aleppo
Male Incidence Rates
0.45
MInc94
MInc95
0.40
MInc96
0.35
MInc97
IR /1000
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
M onths
Aug
Sept
Oct
Nov
Dec
Aleppo
Female Incidence Rates
0.45
FInc94
0.40
FInc95
FInc96
0.35
FInc97
IR /1000
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Jan
Feb
Mar
Apr
May
Jun
Jul
M onths
Aug
Sept
Oct
Nov
Dec
Conclusion
There are few studies of the CL status in
Syria despite the high rates
More research is needed to identify the
epidemiological relationship between
vector, reservoir and host and to limit the
spread of the disease.