Cutaneous leishmaniasis in Syria

LeishmaniasisIntroduction

Infectious disease caused by intracellular protozoan parasites of the genus Leishmania

visceral, cutaneous, and mucocutaneous

Visceral Leishmaniasis

Known as kala azarCharacterized 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 ulcersDestructive 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 projectsweather variabilitychanges in reservoir densities, andannual 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 typeCauses moist cutaneous lesionsOccurs in southern districts of

SyriaReservoir 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 monthsUlcers appear on the extremitiesSpontaneous healing occurs within 3

to 6 months, leaving a depigmented pitted scar

Rodent Sandfly Human

Leishmania majorMode of Transmission

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 regionsSoils 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 infectionCausative parasite in northern districtsTransmitted by the sandfly Plebotomus

sergenti

Leishmania tropica Occurrence

Spreads in areas of

urban centershigher altitudes temperate climatearid, cold and warm weather

Leishmania tropica

Incubation period 2 months > a yearLesion 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 tropicaMode 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

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

1990 1991 1992 1993 1994 1995 1996 1997

Year

No

. C

as

es

Incidence Rate per 1000 in each district between 1990-1997

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

1990 1991 1992 1993 1994 1995 1996 1997

Years

IR/1

00

0

Damas City IR

Damas Sub IR

Daraa IR

Suweida IR

Qunaitra IR

Homs IR

Hama IR

Aleppo IR

Idleb IR

Lattakia IR

Tartous IR

DeirAlZor IR

Rakka IR

Hasakeh IR

IR/1000 in Damascus Suburbs b/w 1994-1997 according to sex

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

1994 1995 1996 1997

Years

IR/1

000

Total IR

Male IR

Female IR

IR/1000 in Aleppo b/w 1994-1997 according to sex

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

1994 1995 1996 1997

Year

IR/1

000

Total IR

Male IR

Female IR

IR/100 in Damascus Suburbs b/w 1994-1997 according to age groups

0.00

1.00

2.00

3.00

4.00

5.00

6.00

1994 1995 1996 1997

Years

IR/1

000

IR<1 yr

IR1-4 yr

IR5-14 yr

IR15+ yr

IR/100 in Aleppo b/w 1994-1997 according to age groups

0.00

1.00

2.00

3.00

4.00

5.00

6.00

1994 1995 1996 1997

Year

IR/1

000

IR <1yr

IR 1-4yrs

IR 5-14yrs

IR 15+yrs

Damascus Suburbs Total Incidence Rates

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Months

IR/1

000

TInc94

TInc95

TInc96

TInc97

Damascus SuburbsMale Incidence Rates

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Months

IR/1

000

MInc94

MInc95

MInc96

MInc97

Damascus SuburbsFemale Incidence Rates

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Months

IR/1

000

FInc94

FInc95

FInc96

FInc97

AleppoTotal Incidence Rates

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Months

IR/1

00

0

TInc94

TInc95

TInc96

TInc97

AleppoMale Incidence Rates

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Months

IR /

10

00

MInc94

MInc95

MInc96

MInc97

AleppoFemale Incidence Rates

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

Jan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec

Months

IR /

10

00

FInc94

FInc95

FInc96

FInc97

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.