Vector-borne diseases are exceptionally sensitive to climate change. Predicting vector occurrence in specific regions is a challenge that disease control programs must meet in order to plan and execute control interventions and climate change adaptation measures. Recently, an increasing number of scientific articles have applied ecological niche modelling (ENM) to study medically important insects and ticks. With a myriad of available methods, it is challenging to interpret their results. Here we review the future projections of disease vectors produced by ENM, and assess their trends and limitations. Tropical regions are currently occupied by many vector species; but future projections indicate poleward expansions of suitable climates for their occurrence and, therefore, entomological surveillance must be continuously done in areas projected to become suitable. The most commonly applied methods were the maximum entropy algorithm, generalized linear models, the genetic algorithm for rule set prediction, and discriminant analysis. Lack of consideration of the full-known current distribution of the target species on models with future projections has led to questionable predictions. We conclude that there is no ideal ‘gold standard’ method to model vector distributions; researchers are encouraged to test different methods for the same data. Such practice is becoming common in the field of ENM, but still lags behind in studies of disease vectors.

Leishmania parasites alternate in their life cycle between promastigote stages that develop in the gut of phlebotomine sand flies and amastigotes residing inside phagocytic cells of vertebrate hosts. For experimental infections of sand flies, promastigotes are frequently used as this way of infection is technically easier although ingestion of promastigotes by sand flies is unnatural. Here we aimed to answer a critical question, to what extent do promastigote-initiated experimental infections differ from those initiated with intracellular amastigotes. We performed side-by-side comparison of Leishmania development in Phlebotomus argentipes females infected alternatively with promastigotes from log-phase cultures or amastigotes grown ex vivo in macrophages. Early stage infections showed substantial differences in parasite load and representation of morphological forms. The differences disappeared along the maturation of infections; both groups developed heavy late-stage infections with colonization of the stomodeal valve, uniform representation of infective metacyclics and equal efficiency of transmission. The results showed that studies focusing on early phase of Leishmania development in sand flies should be initiated with intracellular amastigotes. However, the use of promastigote stages for sand fly infections does not alter significantly the final outcome of Leishmania donovani development in P. argentipes and their transmissibility to the vertebrate host.

The distribution of phlebotomine sand flies is widely reported to be changing in Europe. This can be attributed to either the discovery of sand flies in areas where they were previously overlooked (generally following an outbreak of leishmaniasis or other sand fly-related disease) or to true expansion of their range as a result of climatic or environmental changes. Routine surveillance for phlebotomines in Europe is localized, and often one of the challenges for entomologists working in non-leishmaniasis endemic countries is the lack of knowledge on how to conduct, plan and execute sampling for phlebotomines, or how to adapt on-going sampling strategies for other haematophagous diptera. This review brings together published and unpublished expert knowledge on sampling strategies for European phlebotomines of public health concern in order to provide practical advice on: how to conduct surveys; the collection and interpretation of field data; suitable techniques for the preservation of specimens obtained by different sampling methods; molecular techniques used for species identification; and the pathogens associated with sand flies and their detection methods.

Sand fly saliva plays an important role in Leishmania transmission. We characterized the host antibody response to saliva from 3 sand fly species. Specific IgG was observed in sera from experimentally bitten mice as well as in sera from individuals living in the endemic area of Leishmania tropica in Sanliurfa, Turkey. Sera of Sanliurfa inhabitants showed high IgG levels against saliva of Phlebotomus sergenti and P. papatasi, the 2 most abundant sand fly species in this area, but did not react with saliva of the New World sand fly, Lutzomyia longipalpis. Patients with active Le. tropica lesions possessed significantly higher anti-P. sergenti IgG levels than the healthy individuals from the same place while anti-P. papatasi IgG levels were equal in both groups. Major protein bands in P. papatasi and P. sergenti saliva reacted with both, human and mice sera; in P. papatasi, however, mouse IgG recognized preferentially the 42 kDa protein band while the human IgG reacted strongly with the 30 kDa band. Our data suggest that the antibody response to sand fly saliva could be used for monitoring the exposure of humans and other hosts to sand flies and might be used as a marker of risks for Leishmania transmission in endemic areas.

Studies were commenced to collect and identify the phlebotomine sandflies found in Nairobi. These studies were also aimed at determining their numbers as well as assessing the effects of seasonal changes on the sandfly population. Four trapping methods, namely, light traps, sticky traps, aspiration and human bait were employed. Eight species and one undescribed species were recorded over a period of 6 months. The identified species included Phlebotomus guggisbergi (Kirk and Lewis), P. rodhaini (Parrot), Sergentomyia adleri (Theodor), S. harveyi (Heisch, Guggisberg and Teesdale) and S. bedfordi (Newstead) and an undescribed species. Most of the sandfly species trapped showed seasonal prevalence. The seasonal variation was closely related to the weather conditions. Sandflies were found in termite mounds, animal burrows, caves and dugouts some of which were near human habitations. Termite mounds and animal burrows were the most preferred habitats.

The ability of a Kenyan sandfly species, Sergentomyia ingrami, to feed on various species of native or indigenous and exotic or introduced plants of Kenya was investigated using the Anthrone test. Some flies contained more sugar than others when they were tested after exposure to the plants.

A number of natural and man-made habitats in Marigat area of Kenya were surveyed for sandflies in 1985/86. Of the 98,573 adult sandflies collected, 2.7 % belonged to the genus Phlebotomus and 97.3% to Sergentomyia. Relative abundance of sandflies of the genus Phlebotomus was four times higher in burrows than in termite hills, while sandflies of the genus Sergentomyia collected from termite hills were twice as numerous as those from burrows. Termite hills had the highest sandfly population compared to other sites, followed by tree holes and animal burrows. Fifteen species were identified, of which five belonged to Phlebotomus and 10 to Sergentomyia. The most abundant and widespread species were Sergentomyia antennatus, S. bedfordi, S. ingrami, Phlebotomus martini, S. schwetzi, S. africanus and P. duboscqi. Sandflies of both genera were present for the greater part of the year. Most species of sandflies decreased in numbers during the dry season. High population densities of sandflies were recorded during the wet period. Correlations between relative abundance of sandfly vectors of leishmaniases and rainfall were positive. However, none of the correlation coefficients was statistically significant.

Field investigations were carried out in northern Nigeria to determine the prominent natural habitats of phlebotomine sandflies. Two biotopes, termite hills and rock crevices, were identified as the major habitats with the termite hills being the most significant. All the 12 species (Phlebotomus duboscqi, P. rodhaini, Sergentomyia antennula, S. bedfordi, S. africana, S. schwetzi, S. ingrami, S. adleri, S. clydei, S. buxtoni, S. affinis and S. christophersi) identified in this study came from this source. Only a small number of samples representing a few species were collected from the three other habitats (tree holes, animal burrows and a cave) investigated. The distribution of the sandflies was found to be influenced by the availability of suitable biotopes and physico-chemical composition of the soil.

Investigations of the phlebotomine sandflies fauna in a visceral leishmaniasis focus of Aba Roba in Ethiopia were carried out. This resulted in finding Phlebotomus celiae for the first time in the country. Previously, this species was incriminated as a vector of visceral leishmaniasis in Kitui, Kenya where the disease is endemic. It is possible that P. celiae has a wide distribution covering areas of similar ecological niches as those of its first description.

Adults of various phlebotomine sandfly species were obtained from leishmaniases endemic foci in Kenya using several trapping methods. Ten species were successfully reared from egg to adult in the laboratory; and large colonies of Sergentomyia schwetzi, S. bedfordi, S. ingrami, S. antennatus, S. adleri, S. garnhami, Phlebotomus duboscqi and P. martini established. Generally, the development of Phlebotomus spp. from egg to adult took longer (54.7–57.2 days) than Sergentomyia spp. whose developmental time with the exception of S. garnhami, varied between 36.5–42.3 days.

Establishment and maintenance of a laboratory colony of Phlebotomus argentines are described which presently is in the nineteenth generation. Larvae were reared in modified plastic vials and were fed with a newly prepared food. Emerged flies were kept in adult holding cages at 50–90% r.h. and 25–26°C and provided with 30% sucrose solution. The average development time (egg to adult) of each generation in the laboratory was about 32 days at 28–31°C. Adult females were fed blood on hamsters, humans and white mice. Observations were made on mating behaviour, host preference, oviposition, effect of temperature, etc.

Studies on breeding sites of Phlebotomus duboscqi, a vector of Leishmania major, were intensified in Marigat, Baringo District, Kenya using the soil incubation technique, following the previously successful attempt to look for sandfly breeding sites. Soil samples obtained from nest areas of the animal burrows yielded Phlebotomus duboscqi and Sergentomyia ingrami. These two species had been shown to harbour L. major parasites inside animal burrows. Other phlebotomine sandflies recovered from these same breeding sites included P. martini, P. rhodhaini, S. bedfordi, S. africanus, S. antennatus and S. graingeri

Five (Sergentomyia antennatus, S. garnhami, S. schwetzi, S. ingrami and S. adleri) of the six species of sandflies fed on mammalian blood containing cultured Leishmania donovani promastigotes on day 0, were able to feed through cockerel skin membranes at 5.5, 10, 34.3, 45.7 and 95% feeding rates, respectively. Sergentomyia bedfordi was able to feed on mammalian blood only through a lizard skin membrane at 100% feeding rate. Promastigotes were found in 9.3, 25 and 37.5% of S. schwetzi, S. adleri and S. ingrami respectively, dissected on days 3–9.

The results open way for artificial feeding of Kenyan sandflies on mammalian blood through membranes, and indicate that it is necessary to select the type of membrane depending on sandfly species. The ability of L. donovani to develop in Kenyan sandflies is being investigated to experimentally establish and confirm the importance of various genera and species in the epidemiology of leishmaniasis.

The vectors of Leishmania major were investigated in Marigat, Baringo District, Kenya, a focus of both visceral and dermal leishmaniases. These studies resulted in the discovery of the resting sites of Phlebotomus duboscqi, a known vector of L. major, and of alternate principal resting sites of Phlebotomus martini, a known vector of visceral leishmaniasis. Furthermore, Sergentomyia ingrami was incriminated as a possible vector of L. major among susceptible rodents inside burrows. Trapping methods which have resulted in the discovery of the resting sites of these phlebotomine sandflies are presented in this paper.

The paper reviews advances in our understanding of the vectorial capacity and vector–parasite relationship in Kenyan sandflies since the early 1900s (when sandflies were first reported in Kenya). Of the 38 species of sandflies known to occur in Kenya to date, three (Phlebotomus pedifer, P. martini and P. duboscqi) can naturally carry biochemically and serologically confirmed Leishmania (aethiopica, donovani and major, respectively) and 12 (Phlebotomus rhodhaini, Sergentomyia garnhami, S. squamipleuris, S. africanus, S. kirki, S. ingrami, S. antennatus, S. bedfordi, S. schwetzi, S. affinis, S. graingeri and S. clydei) carry various flagellates of biochemically or serologically unknown character.

Current research on naturally infected wild-caught sandflies indicates that L. aethiopica promastigotes have close association with structures resembling a peritrophic membrane and invade P. pedifer gut cells. Promastigotes invade the malpighian tubules of S. garnhami and S. antennatus.

Studies on laboratory-reared sandflies show that P. martini is susceptible to L. donovani amastigotes and that cultured promastigotes of L. donovani can survive in the guts of S. schwetzi, S. ingrami and S. adleri.

Experimental infection of sandflies with Leishmania is discussed and priorities for laboratory work set.

Investigations into the vectorial capacity of wild caught Phlebotomus pedifer by feeding them on volunteer patients were carried out inside one of the caves of Mt Elgon. Female P. pedifer were fed on lesions of cutaneous leishmaniasis patients to determine the route of infection and infection rates in the flies and hence their vectorial capacity. The flies were kept for periods of 3–8 and 9–13 days before dissections were carried out. The results indicate that the longer period (9–13 days) yielded a higher infection rate. All parasite isolations from flies which were injected subcutaneously caused cutaneous lesions in the nose of the experimental hamsters. All infections were concentrated in the anterior stations of the gut of the experimental sandfly species P. pedifer.

Investigations on sandfly breeding sites in Marigat, Baringo District, in Kenya were carried out using a soil incubation technique. Soil samples from natural resting sites were collected, incubated and observed daily for emerging adult phlebotomine sandflies. This technique proved to be the best in the recovery of phlebotomine sandflies from known resting sites. Ten sandfly species were recovered from soil collected from animal burrows and termite hills.

Studies of outer chorionic sculpturing of eggs of four species of sandflies were carried out by the use of scanning electron microscope. Two species, P. martini and S. garnhami, which utilize similar resting sites, termite hill ventilation shafts, had similar chorionic sculpturing, while two other species (S. bedfordi and S. kirki) which use several resting sites, i.e. rock crevices, tree holes and termite ventilation shafts, had chorionic sculpturings which were dissimilar.

Studies of the epidemiology of visceral leishmaniasis in the West Pokot focus have revealed that Sergentomyia bedfordi, S. antennatus and S. schwetzi are the most abundant sandfly species. The latter have been shown to feed mainly on lizards. Phlebotomus martini was encountered in termite hills in the ventilation shafts, and showed an even distribution among the termite hills throughout the district where kala-azar cases were detected. Investigations into the relationship between termite hills and the presence of kala-azar cases in various homes were carried out. All homes afflicted with kala-azar had a termite hill or hills within a 10-m radius. The period of time spent in own homestead by each kala-azar case was to establish if each kala-azar patient contracted the disease in the focus of investigation.

Sandflies caught from termitaria at Tseikuru (Kitui District) and Masinga (Machakos District) were dissected and examined for the presence of Leishmania. Leishmanial parasites were found in the guts of 12 out of 112 Sergentomyia garnhami from Tseikuru and in 2 out of 48 S. antennatus from Masinga. Five of the 12 S. garnhami and 1 of the 2 S. antennatus had leishmanial parasites in the malpighian tubules. Electron microscopic investigations revealed that in the malpighian tubules of S. garnhami the parasites were either free in the lumen or in close contact with the basement membrane.