Current Approaches to the Prevention and Control of Leishmaniasis Vectors

Phlebotomine sand flies (Diptera: Psychodidae) of the Maghreb region: A systematic review of distribution, morphology, and role in the transmission of the pathogens

BACKGROUND

Phlebotomine sand flies (Diptera: Psychodidae) are important vectors of various human and animal pathogens such as Bartonella bacilliformis, Phlebovirus, and parasitic protozoa of the genus Leishmania, causative agent of leishmaniases that account among most significant vector-borne diseases. The Maghreb countries Mauritania, Morocco, Algeria, Tunisia, and Libya occupy a vast area of North Africa and belong to most affected regions by these diseases. Locally varying climatic and ecological conditions support diverse sand fly fauna that includes many proven or suspected vectors. The aim of this review is to summarize often fragmented information and to provide an updated list of sand fly species of the Maghreb region with illustration of species-specific morphological features and maps of their reported distribution.

MATERIALS AND METHODS

The literature search focused on scholar databases to review information on the sand fly species distribution and their role in the disease transmissions in Mauritania, Morocco, Algeria, Tunisia, and Libya, surveying sources from the period between 1900 and 2020. Reported distribution of each species was collated using Google Earth, and distribution maps were drawn using ArcGIS software. Morphological illustrations were compiled from various published sources.

RESULTS AND CONCLUSIONS

In total, 32 species of the genera Phlebotomus (Ph.) and Sergentomyia (Se.) were reported in the Maghreb region (15 from Libya, 18 from Tunisia, 23 from Morocco, 24 from Algeria, and 9 from Mauritania). Phlebotomus mariae and Se. africana subsp. asiatica were recorded only in Morocco, Ph. mascitti, Se. hirtus, and Se. tiberiadis only in Algeria, whereas Ph. duboscqi, Se. dubia, Se. africana africana, Se. lesleyae, Se. magna, and Se. freetownensis were reported only from Mauritania. Our review has updated and summarized the geographic distribution of 26 species reported so far in Morocco, Algeria, Tunisia, and Libya, excluding Mauritania from a detailed analysis due to the unavailability of accurate distribution data. In addition, morphological differences important for species identification are summarized with particular attention to closely related species such as Ph. papatasi and Ph. bergeroti, Ph. chabaudi, and Ph. riouxi, and Se. christophersi and Se. clydei.

Toxicity of Thiamethoxam on Field-Collected Sand Flies (Diptera: Psychodidae) From Different Regions of Turkey

Phlebotomine sand flies (Diptera: Psychodidae) are the vectors of human and canine leishmaniasis, sand fly fever, and other arboviruses and bacteria. The control of sand flies is recommended by World Health Organization throughout the world. In this study, we investigated the susceptibility of field-collected sand flies against thiamethoxam in Turkey. The adult sand flies collected were from five different locations in three provinces; Yeşilöz and Büyükpınar districts in Antalya province, Develi district in Kayseri province, and Üçpınar and Bayındırlık districts in Manisa province. They were investigated using two different doses (0.125 and 0.25 g ai/m2) of thiamethoxam under laboratory conditions. After 1-h exposure, all sand flies were found highly susceptible to thiamethoxam and both test doses caused 100% mortality after 24 h. Considering the KDT50 time, flies collected from Yeşilöz district in Antalya province were found to be most sensitive and flies collected from Üçpınar district in Manisa province were found as the most resistance to thiamethoxam. The results show that Turkish sand flies were highly susceptible to thiamethoxam and it can be used for the control of sand flies in the field.

Imported leishmaniasis in a dog in a sandfly-populated area in northeastern Romania

We report the importation of a clinical case of canine leishmaniasis (CanL) in Romania, a country where several types of sandflies are present with the potential to develop a new focus of CanL. The Staffordshire Bull Terrier dog was imported into Romania from Spain 1.5 y before he developed clinical symptomatology that included proliferative dermatitis, lymphadenomegaly, and bilateral uveitis. Hematologic analyses showed regenerative anemia and subacute inflammation. Cytologic examination of lymph node fine-needle aspirates revealed Leishmania spp. amastigotes that were confirmed as L. infantum by PCR. The importation of canine leishmania cases into nonendemic areas in which the vector exists could potentially lead to the silent spread of a disease posing a significant public health threat.

Species of sand flies (Diptera: Psychodidae) collected from natural reserves in the Pacific and Darien regions of Colombia

INTRODUCTION

The departments of Chocó and Antioquia in Colombia show climatic and vegetation conditions favoring the establishment of vector species of the genus Lutzomyia and the transmission of Leishmania spp. to human populations entering conserved forest environments.

OBJECTIVE

To report the species of Phlebotomine sandflies present in three natural reserves in the Darien and Pacific regions of Colombia.

MATERIALS AND METHODS

Sand flies were collected specifically in the natural reserves El Aguacate (Acandí, Chocó), Nabugá (Bahía Solano, Chocó) and Tulenapa (Carepa, Antioquia). Sand flies were collected with CDC light traps, active search in resting places and Shannon traps. The taxonomic determination of species was based on taxonomic keys. For some species of taxonomic interest, we evaluated the partial sequences of the 5' region of COI gene.

RESULTS

A total of 611 adult sand flies were collected: 531 in Acandí, 45 in Carepa and 35 in Bahía Solano. Seventeen species of the genus Lutzomyia, three of the genus Brumptomyia and one of the genus Warileya were identified. The genetic distances (K2P) and grouping supported (>99%) in the neighbor joining dendrogram were consistent for most established molecular operational taxonomic units (MOTU) of the Aragaoi group and clearly confirmed the identity of Lu. coutinhoi.

CONCLUSION

Species that have importance in the transmission of leishmaniasis in Acandí, Bahía Solano and Carepa were identified. The presence of Lu. coutinhoi was confirmed and consolidated in Colombia.

Impact of control measures and dynamics of sand flies in southern Brazil

We report the results of control measures introduced to reduce the density of sand flies in domiciles and subsequent monitoring of the effects of these measures on the sand fly populations. The most common species of sand flies were Nyssomyia neivai and Nyssomyia whitmani, which are naturally infected by Leishmania. A total of 268,382 (93.4%) sand flies were collected in ecotypes constructed with the aim of attracting sand flies, and 19,091 (6.6%) sand flies were collected in the ecotypes consisting of residences and other buildings. Human actions determine the growth or reduction of the sand fly population in human-occupied space. Understanding the dynamics of sand flies in this environment can substantially contribute to the prevention of cutaneous leishmaniasis.

Behavioral evidence for the presence of a sex pheromone in male Phlebotomus papatasi scopoli (Diptera: Psychodidae)

Phlebotomus papatasi (Diptera: Psychodidae) is the Old World sand fly vector of zoonotic cutaneous leishmaniasis caused by Leishmania major (Trypanosomatidae: Kinetoplastida), a debilitating and disfiguring protist parasitic disease prevalent throughout southern Mediterranean countries, the Middle East, as well as southern and eastern European countries, where it is regarded as a serious public health problem. Little is known of the mating ecology of P. papatasi, and, in particular, the role (if any) of pheromones is not known. In this laboratory- and field-based study, we have shown that a male-produced sex pheromone exists in P. papatasi. Young female P. papatasi are attracted to the headspace volatiles of small groups of males, males and females together, but not females alone. Males were not attracted to males, females, or mixed groups of males and females in the laboratory. Larger groups of males or males and females together were repellent in the laboratory study. Field experiments showed that Centers for Disease Control (CDC) light traps baited with small groups of males and females together were attractive to females, but not males. CDC traps baited with large groups of males and females together caught significantly fewer females and males than the control traps; however, the proportion of females caught compared with males overall was much higher than with CDC traps baited with small numbers of males and females. These results suggest that females may be attracted in preference to males to the vicinity of the baited traps and are highly sensitive to the concentration of male pheromone. It also suggests that P. papatasi mating behavior is fundamentally different from that of Lutzomyia longipalpis, where large mating aggregations of males and females occur.

Discovery of diurnal resting sites of phlebotomine sand flies in a village in southern Egypt

In an attempt to find diurnal resting sites of adult phlebotomine sand flies, potential phlebotomine adult habitats were aspirated in the village of Bahrif in Aswan, Egypt. During this survey, sand flies were aspirated from low (30-45 cm high) irregular piles of mud bricks found under high date palm canopies between the village and the Nile River. There were 5 males and 7 females of Phlebotomus papatasi and 3 males of Sergentomyia schwetzi. Six of the 7 aspirated females were engorged with blood. A total of 78 sand flies was captured on 3 glue boards placed overnight on the ground next to the mud bricks. Attempts to aspirate sand flies from adjacent walls and plants were unsuccessful. The identification of diurnal resting sites in less structured habitats may ultimately lead to more effective adult sand fly control.