Aspects of the bionomics of Phlebotomus sergenti sandflies from an endemic area of anthroponotic cutaneous leishmaniasis in Aleppo Governorate, Syria.

Aspects of the bionomics of phlebotomine sandflies (Diptera: Psychodidae) were studied from June to November 2005 in three foci of anthroponotic cutaneous leishmaniasis (ACL) in Aleppo Governorate, Syria, where the agent Leishmania tropica (Wright) (Kinetoplastida: Trypanosomatidae) is transmitted by Phlebotomus sergenti Parrot. Syria has been designated by the World Health Organization as one of four countries in the Old World where cutaneous leishmaniasis is hyperendemic, but little is known about the biology of local vector populations. Standard collections by sticky traps showed two peaks in density, in June and late August. In total, 1840 sandflies were caught, comprising five species: Phlebotomus papatasi (Scopoli) (68.0%); P. sergenti (25.4%); Sergentomyia minuta (Rondani) (6.4%); Phlebotomus tobbi Adler & Theodor (0.1%), and Phlebotomus mascittii canaaniticus Adler & Theodor (0.1%). Similar numbers of P. sergenti were caught indoors (246 specimens) and outdoors (222), whereas P. papatasi was significantly more abundant indoors (1096 specimens) than outdoors (156) (chi(2) = 241, P < 0.01). In total, 212 blood-fed females were tested for host blood determination, of which 176 (83.0%) reacted with anti-species reagent. Results from 20 P. sergenti suggest that this species is an opportunistic feeder, imbibing human, ovine, avian, bovine and feline blood, although more bloodmeals were taken from humans and cattle than expected in relation to the relative proportions of potential hosts present (the forage ratio, FR). The bionomics of P. sergenti are discussed in relation to the inefficacy of control campaigns based on indoor spraying with residual insecticides that have been implemented by the Syrian Ministry of Health to control the epidemics of ACL in the Aleppo Governorate.

Insecticide-treated bednets to prevent anthroponotic cutaneous leishmaniasis in Aleppo Governorate, Syria: results from two trials.

The increasing incidence of anthroponotic cutaneous leishmaniasis (ACL) in Syria, coupled with the inefficacy of residual insecticide spraying to control the disease, have led to the further evaluation of the preventive efficacy of insecticide-treated bednets (ITNs) through large-scale field studies. Two trials were performed in the historical ACL-endemic areas of the Aleppo Governorate. In 1997-1999, a matched-cluster randomized trial was conducted in five intervention (ITNs) and five control (untreated bednets) villages, which involved a population of 10354 in 1321 households. In 2001-2003, a second study was performed in four villages (a population of 9325 in 858 households), which allowed the evaluation of the impact of the interruption of ITN intervention on ACL incidence rates. Both studies not only confirmed the high efficacy of ITNs in preventing ACL during 1 year post-intervention [about 85% (95% CL 76-98%) in the 1997-1999 trial], but also suggested that the interruption of this control measure might restore the pre-intervention disease incidence within 1-2 years. These findings underline the need for a sustainable and durable implementation of ITN-based control of the disease.

Twenty years of cutaneous leishmaniasis in Aleppo, Syria.

Cutaneous leishmaniasis caused by Leishmania tropica has long been associated with Aleppo in Syria. For 20 years up to the mid-1980s, the number of cases reported annually in the city and environs has remained low, not exceeding a few hundred. Since then, there has been a sudden increase to several thousand cases reported each year. The increase seems too great and too sudden to be attributable to improved case detection. Insecticide spraying, begun in 1991, was followed by a reduction in number of cases in 1992, but numbers increased subsequently in spite of continued spraying. The cases are found mainly in areas undergoing development outside the old centre of the city, and may be associated with poor waste disposal and heaps of construction waste.

Evidence for a long-term increase in the incidence of Leishmania tropica in Aleppo, Syria.

We report the results of a short study of the epidemiology of Leishmania tropica in the Sheikh Maksoud District of Aleppo, Syria. The present and past status of infection in a community of about 100,000 people are assessed from prevalence and incidence data obtained by active and passive case detection, and from a skin test survey. L. tropica has apparently been endemic for at least 2-3 human generations in Aleppo, and incidence has increased over the past decade. The current estimated force of infection is 0.174/year, the incidence is about 5%, and the average age of infection is 14 years. L. tropica has the essential characteristics of a cyclic infectious disease, and the recent rise in incidence could be part of a long period cycle. A survey of leishmanial scars seriously underestimated the fraction of persons immune, as scar surveys usually do. We estimate that a passive case registration scheme, which has been established in response to growing concern about leishmaniasis in Aleppo, succeeds in recording and treating about one in 4 cases.