Biodiversity of culicid mosquitoes in rural Neka township of Mazandaran province, northern Iran

BACKGROUND & OBJECTIVES

This paper presents the results of a study on ecological parameters including diversity indices applied on populations of Culicidae mosquitoes (Diptera: Culicidae) from three rural areas (Darvishan, Chalmardi and Khairabad) of Neka township in Mazandaran province, northern Iran.

METHODS

Adult and larval stages of mosquitoes were systematically sampled to obtain data required for measuring diversity of mosquitoes in these areas. Alfa and beta indices were analyzed to compare mosquito diversity. A total of 5270 specimens belonging to four genera and 14 different species were collected and identified.

RESULTS

Evaluation of dominance structure of species showed that culicid mosquitoes of Neka rangelands include one eudominant species, two dominant species, two subdominant species, two rare species and eight subrare species when Heydemann classification was used.

INTERPRETATION & CONCLUSION

Data analysis revealed a higher diversity of mosquitoes in Khairabad with a low degree of interspecific dominance, while Darvishan and Chalmardi recorded the lowest observed diversity and a high degree of interspecific dominance. The cluster analysis based on Jaccard's index indicated the relationship between the categories and indicates that Darvishan and Khairabad are the closest categories in their specific composition.

Field evaluation of phostoxin and zinc phosphide for the control of zoonotic cutaneous leishmaniasis in a hyperendemic area, central Iran

BACKGROUND & OBJECTIVES

ZCL is a growing threat in many rural areas of Iran which involves 17 out of 31 provinces. This study was conducted from April to November 2011 for evaluation of the efficacy of phostoxin and zinc phosphide against rodents.

METHODS

Rodent control operations were carried out using phostoxin and zinc phosphide. To evaluate the effect of rodent control operation on the main vector density, an entomological survey was carried out. The effects of the operation on the disease incidence were also evaluated.

RESULTS

After intervention, the reduction rate of rodent burrows was 32.68% in the village treated with phostoxin and 58.14% in the village treated with zinc phosphide. The number of rodent holes in the control area showed 6.66-fold increase at the end of the study. The incidence of the disease decreased to 19.23 and 11.40 in areas treated with phostoxin and zinc phosphide, respectively. A total of 4243 adult sandflies were collected and identified. The most common and dominant species was Phlebotomus papatasi. In the village treated with phostoxin, the density of P. papatasi in outdoors was lower than indoors. Nevertheless, the density of P. papatasi in the village treated with zinc phosphide was higher in outdoors.

INTERPRETATION & CONCLUSION

It is concluded that phostoxin is less effective and has low safety in comparison with zinc phosphide, so that this rodenticide can be used only in special situations such as lack or ineffective rodenticides and only in the colonies far from human and animal dwelling places in small scales.

Baseline insecticide susceptibility data of Phlebotomus papatasi in Iran

BACKGROUND & OBJECTIVES

Phlebotomine sandflies (Diptera: Psychodidae) play main role in the transmission of different forms of leishmaniasis in the world. Phlebotomus papatasi is the main vector of zoonotic cutaneous leishmaniasis (ZCL) in Iran. There are several control measures for vector control using different classes of insecticides. The aim of this study was to breed the sandflies which were collected from a hyperendemic focus of the disease in central Iran in the laboratory condition and to determine its baseline susceptibility to commonly used insecticides.

METHODS

Sandflies were collected from the field and were reared in insectary. Susceptibility tests were carried out on their generation. Baseline susceptibility of sandflies to DDT and pyrethroids was evaluated based on LT50 values. A total of 1305 specimens were tested using different time intervals. The LT50 and LT90 values were measured according to the WHO standard tests. The results were plotted using probit analysis and regression lines.

RESULTS

The results against female sandflies revealed the LT50 values of 1312.66, 253.66, 36.04, 9.38 and 6 sec to DDT (4%), permethrin (0.75%), deltamethrin (0.1%), cyfluthrin (0.15%) and lambda-cyhalothrin (0.05%), respectively. The figures for male sandflies were 1200.97, 310.10, 18.63, 6.08 and 0.77 sec respectively to the above insecticides.

CONCLUSION

The results of this study could help to provide a clue for implementation of currently used insecticides. Furthermore, a specific guideline is needed for monitoring and evaluation of insecticide susceptibility test against sandflies.

Comparative study on the effectiveness of coumavec® and zinc phosphide in controlling zoonotic cutaneous leishmaniasis in a hyperendemic focus in central iran

BACKGROUND

Zoonotic cutaneous leishmaniasis (ZCL) is an increasing health problems in many rural areas of Iran. The aim of this study was to introduce a new alternative rodenticide to control the reservoirs of ZCL, its effect on the vector density and the incidence of the disease in hyperendemic focus of Esfahan County, central Iran.

METHODS

The study was carried out from January 2011 to January 2012. In intervention areas, rodent control operation was conducted using zinc phosphide or Coumavec®. Active case findings were done by house-to-house visits once every season during 2011-2012. To evaluate the effect of rodent control operation on the vector density, sand flies were collected twice a month using sticky traps.

RESULTS

The reduction rate of rodent holes in intervention areas with Coumavec® and zinc phosphide were 48.46% and 58.15% respectively, whereas in control area results showed 6.66 folds intensification. The Incidence of ZCL significantly reduced in the treated areas. Totally, 3200 adult sand flies were collected and identified in the intervention and control areas. In the treated area with zinc phosphide, the density of Phlebotomus papatasi was higher in outdoors in contrast with the treated area by Coumavec® which the density of the sand fly was higher in indoors.

CONCLUSION

Both rodenticides were effective on the incidence of ZCL and the population of the reservoirs as well. Coumavec® seems to be effective on the outdoor density of the vector. This combination of rodenticide-insecticide could be a suitable alternative for zinc phosphide while bait shyness or behavioral resistance is occurred.

Phlebotomine Sand Flies (Diptera: Psychodidae) in Iran and their Role on Leishmania Transmission

Sand fly research has a long history in Iran beginning with the work of Adler, Theodor and Lourie in 1930 and followed by Mesghali's foundational taxonomic work on sand flies in 1943. Since then, research has been continued unabated throughout the country and official publications report the existence of at least 44 species of sand flies (26 of the genus Phlebotomus and 18 of genus Sergentomyia) in Iran. So far, seven Phlebotomus species and one Sergentomyia species have been collected and described by Iranian researchers for the first time. Natural promastigote infections have been repeatedly found in 13 species of sand flies and modern molecular techniques are used routinely to characterize Leishmania parasite isolates from endemic areas of cutaneous and visceral leishmaniasis. Because of anthropogenic environmental modifications or human population movements, data on phlebotomine sand flies should be regularly updated and verified at least every five years by fieldwork and taxonomy in foci of leishmaniasis, to incriminate vector species of relevance to the ecology of transmission and to support development and implementation of control programs.

Susceptibility Status of Phlebotomus papatasi and P. sergenti (Diptera: Psychodidae) to DDT and Deltamethrin in a Focus of Cutaneous Leishmaniasis after Earthquake Strike in Bam, Iran

BACKGROUND

The cutaneous leishmaniasis (CL) has been occurred in Dehbakri County, located 46 km of Bam District, Kerman Province since 2004-2005. Phlebotomus papatasi is an important vector of zoonotic cutaneous leishmanisis (ZCL) as well as sand fly fever and P. sergenti is considered as main vector of anthroponotic cutaneous leishmaniasis (ACL) in Iran. There are several measures for vector control with emphasizing on insecticides. The objective of this study was to determine the baseline susceptibility of leishmaniasis vectors to the DDT and deltamethrin in an endemic focus of CL in southern Iran.

METHODS

Baseline susceptibility tests were carried out on field collected strains of P. papatasi and P. sergenti and tested with WHO impregnated papers with DDT 4.0% and deltamethrin 0.05% in the focus of disease in Dehbakri County during summer 2010. The values of LT(50) and LT(90) were determined using probit analysis and regression lines.

RESULTS

The LT(50) value of DDT 4.0% and deltamethrin 0.05% against P. papatasi was 20.6 and 13.6 minutes respectively. The same data for P. sergenti were ranged between 21.8 and 17.7 minutes.

CONCLUSION

The results of tests will provide a guideline for implementation of vector control using pesticides such as impregnated bed nets, indoor residual spraying and fogging.

Production and Purification of Anti-Rhombomys opimus Immunoglobulins

BACKGROUND

Zoonotic cutaneous leishmaniasis (ZCL) is an increasing public health problem in some endemic regions. Horseradish peroxidase (HRP) conjugated rabbit anti-Rhombomys opimus (R. opimus) Ig is needed for immunoblotting and ELISA tests used to explore the immune response of the rodents against the sand fly saliva. In this study, the production of HRP conjugated rabbit anti-R. opimus Ig was conducted for the first time.

METHODS

Rhombomys opimus Ig was purified from serum by protein G affinity chromatography column and injected into rabbit to produce anti-R. opimus Ig antibody. The titration of antibody against R. opimus Ig in rabbit serum was checked using indirect ELISA. Rabbit anti-R. opimus Ig was purified by Sepharose-4B-R. opimus Ig column. Reactivity of this antibody was assessed by indirect ELISA and was conjugated to HRP by periodate method.

RESULTS

Approximately 3.5 mg Ig was purified from 1 ml R. opimus serum using protein G affinity chromatography column. The molecular weight of purified R. opimus Ig was estimated about 150 kDa by SDS-PAGE. Nearly 2.3 mg rabbit anti-R. opimus Ig was purified from 1 ml immunized rabbit serum. The purified antibody was conjugated to HRP and the optimum titer of HRP conjugated rabbit anti-R. opimus Ig was determined as 1:8000 using direct ELISA.

CONCLUSION

HRP conjugated rabbit anti-Gerbil IgG has been produced by a few companies, but to our knowledge HRP conjugated rabbit anti-R. opimus Ig is not commercially available. Production of HRP conjugated rabbit anti-R. opimus Ig is considerably helpful for immunological studies of R. opimus, the main reservoir host of ZCL in Iran as well as some other countries.

Molecular Detection of Leishmania infantum in Naturally Infected Phlebotomus perfiliewi transcaucasicus in Bilesavar District, Northwestern Iran

BACKGROUND

Visceral leishmaniasis is caused by Leishmania infantum, transmitted to humans by bites of phlebotomine sand flies and is one of the most important public health problems in Iran. To identify the vector(s), an investigation was carried out in Bilesavar District, one of the important foci of the disease in Ardebil Province in northwestern Iran, during July-September 2008.

METHODS

Using sticky papers, 2,110 sand flies were collected from indoors (bedroom, guestroom, toilet and stable) and outdoors (wall cracks, crevices and animal burrows) and identified morphologically. Species-specific amplification of promastigotes revealed specific PCR products of L. infantum DNA.

RESULTS

SIX SAND FLY SPECIES WERE FOUND IN THE DISTRICT, INCLUDING: Phlebotomus perfiliewi transcaucasicus, P. papatasi, P. tobbi, P. sergenti, Sergentomyia dentata and S. sintoni. Phlebotomus perfiliewi transcaucasicus was the dominant species of the genus Phlebotomus (62.8%). Of 270 female dissected P. perfiliewi transcuacasicus, 4 (1.5%) were found naturally infected with promastigotes.

CONCLUSION

Based on natural infections of P. perfiliewi transcaucasicus with L. infantum and the fact that it was the only species found infected with L. infantum, it seems, this sand fly could be the principal vector of visceral leishmaniasis in the region.

Species composition and diversity of mosquitoes in neka county, mazandaran province, northern iran

BACKGROUND

Regarding to the significant of the possibility of the malaria epidemic and nuisance of mosquitoes during the active season, the fauna and some ecological activities of mosquitoes in related to tree holes were investigated from April to December 2009 in Neka county of Mazandaran Province, northern Iran.

METHODS

Larval collection was carried out from natural, artificial breeding places, and tree holes inside the forest in Neka County, Mazandaran Province in 2009. In addition, human bait net trap collection was conducted using suction tube several times during this investigation.

RESULTS

Four genera and five species were found in tree holes. Anopheles plumbeus, Culiseta annulata, Culex pipiens, and Ochlerotatus geniculatus were collected by larval collection whereas, Ochlerotatus pulcritarsis was found by adult collection. Overall Cx. pipiens 44.6%, Oc. geniculatus 32.6%, An. plumbeus 22.5%, and Cs. annulata 0.3% were collected by larval collection. During the bait net collection five specie were identified including: Oc. geniculatus 55.87%, Oc. echinus 1.33%, Oc. pulcritarsis 8.8%, Cx. pipiens 33.8%, and An. plumbeus 0.2%. Cs. annulata larvae was detected for the first time with a low abundance in tree cavity.

CONCLUSION

Tree holes were found the main habitat for the species of Oc. geniculatus. The species of Cs. annulata was found in tree holes.

Dynamics of Leishmania infection rates in Rhombomys opimus (Rodentia: Gerbillinae) population of an endemic focus of zoonotic cutaneous leishmaniasis in Iran

Zoonotic cutaneous leishmaniasis (ZCL) due to Leishmania major is a great public health problem in the Old World. Leishmania major is widely distributed in populations of rodents in arid and savannah regions. In this study, seasonal variation of natural infection with Leishmania parasites in Rhombomys opimus (Rodentia: Gerbillinae) population of an endemic focus of ZCL in Iran was monitored. The study was conducted from October 2007 to October 2008 in the central part of the country. Nested polymerase chain reaction (PCR) assay was used for the detection and identification of Leishmania parasites, and the results were confirmed by PCR-restriction fragment length polymorphism (RFLP). The results showed that Leishmania infection rate was 55.8% (29 out of 52 gerbils) using nested PCR. The highest and lowest Leishmania infection rates were observed in fall and summer, respectively. Gerbils that were found to be infected only with L. major were 5.8%, and that with Leishmania turanica were 23.1%. A mixed natural infection was seen in the rodents with L. major and L. turanica (21.2%), with L. major and L. gerbilli (1.9%), and with all the three species (3.9%). Leishmania major infection alone was seen in fall and winter whereas mixed infection of L. major and L. turanica was observed in all seasons except in summer. Leishmania turanica infection was observed throughout the year. It is concluded that L. major, L. gerbilli, and L. turanica circulate in the population of R. opimus in central part of Iran. Leishmania major infection is usually accompanied by L. turanica in naturally infected gerbils with the highest rate in fall. It is recommended that the role of L. turanica in the epidemiology and transmission of ZCL should be reconsidered.

Differential Responses of Anopheles stephensi (Diptera: Culicidae) to Skin Emanations of a Man, a Cow, and a Guinea Pig in the Olfactometer

BACKGROUND

Biting habit of mosquitoes plays an important role in the epidemiology of mosquito-borne diseases. Mosquitoes use a set of elaborate sensory modalities to find their preferred hosts by exploiting cues emanating from a nearby host. It has been suggested that the chemical profile of skin can provide further support for anthropophilic mosquito species to find their suitable hosts. This study aimed at revealing the value of skin emanation for a zoophilic species like Anopheles stephensi as a model.

METHODS

Skin emanations of a man, a cow and a Guinea pig were collected by ethanol soaked cottons. Upwind responses of mosquitoes to 100 and 200 μl of filtered skin materials were non-competitively explored in a dual-choice olfactometer. L-lactic acid and other chemical content of the skin samples were identified by an enzymatic kit and GC-MS, respectively.

RESULTS

Unexpectedly, only human skin emanation was resulted in the statistically significant activation and attraction responses of An. stephensi in the wind tunnel. L-lactic acid content of this skin sample was 10 and 29 times more than the cow and the Guinea pig, respectively. The possible role of lactic acid and a few other identified compounds have been discussed here.

CONCLUSION

Anopheles stephensi showed higher and more specific upwind responses to human skin emanation in the olfactometer. Undoubtedly, the thorough explanation of this unexpected finding needs further investigation. But, if new data verify this result, then, it may be necessary to reconsider the role of skin emanation and thence the human blood index and vectorial capacity of this zoophilic mosquito.

Sand fly Surveillance within an Emerging Epidemic Focus of Cutaneous Leishmaniasis in Southeastern Iran

BACKGROUND

Cutaneous leishmaniasis due to Leishmania major has become a hot topic in Iran. The objective of this study was to determine some ecological aspects of sand flies in the study area.

METHODS

Sand flies were collected biweekly from indoors and outdoors fixed places in the selected villages, using 30 sticky paper traps from the beginning to the end of the active season of 2006 in Kerman Province, south of Iran. The flies were mounted and identified. Some blood fed and gravid female sand flies of rodent burrows and indoors were dissected and examined microscopically for natural promastigote infection of Leishmania parasite during August to September.

RESULTS

In total, 2439 specimens comprising 8 species (3 Phlebotomus and 5 Sergentomyia) were identified. The most common sand fly was P. papatasi and represented 87.1% of sand flies from indoors and 57.2% from outdoors. The activity of the species extended from April to end October. There are two peaks in the density curve of this species, one in June and the second in August. Natural promastigote infection was found in P. papatasi (12.7%).

CONCLUSION

Phlebotomus papatasi is considered as a probable vector among gerbils and to humans with a high percentage of promastigote infection in this new focus of cutaneous leishmaniasis. The Bahraman area which until recently was unknown as an endemic area seems now to represent a focus of zoonotic cutaneous leishmaniasis transmission in Iran.

Molecular epizootiology of rodent leishmaniasis in a hyperendemic area of iran

BACKGROUND

Zoonotic cutaneous leishmaniasis (ZCL) is an expanding disease and public health problem in Iran. In the current study, natural Leishmania infection rate and seasonal fluctuation of the infection in Rhombomys opimus population of a hyperendemic focus of ZCL in Iran was investigated.

METHODS

The study was conducted from October 2006 to October 2008 in Esfahan Province, central part of Iran. An extensive sampling of rodents using Sherman traps was done in different seasons. Nested PCR assay was used for detection and identification of Leishmania species and the results were confirmed using PCR-RFLP.

RESULTS

Leishmania infection rate was 58.6% (34 of 58) using nested PCR. 44.8% of the gerbils were infected only with L. turanica and 1.7% with L. gerbilli alone. A mixed natural infection with L. major and L. turanica was seen in 12.1% of the rodents. L. major infection alone was not seen in R. opimus population in the study area. The highest and lowest Leishmania infection rates were observed in fall and spring respectively. L. turanica infection was observed throughout the year whereas mixed infections with L. major and L. turanica was not seen in spring.

CONCLUSION

It is concluded that in the study area, L. major, L. gerbilli and L. turanica circulate in the population of R. opimus. Leishmania major infection usually accompanied by L. turanica in naturally infected gerbils with the highest rate in fall. It is recommended that the role of L. turanica in the epidemiology and transmission of ZCL be revisited.

High Performance Thin Layer Chromatography Analysis of Deltamethrin Residue on the Impregnated Bed Nets during a Leishmaniasis Control Program in Iran

BACKGROUND

The control of leishmaniasis, a tropical neglected disease, has been concern of Iranian health authorities due to the increasing number of cases during the last two decades. The objective of this study was to determine deltamethrine residue on the impregnated bed nets using HPTLC technique in a leishmaniasis control program in Iran.

METHODS

During this experimental study, a total of 130 small pieces of polyester netting were sewn to top, upper, and lower sides of some bed nets and then were impregnated with deltamethrin. The treated bed nets were distributed in Isfahan and Mashhad areas in April 2003. The samples were cut randomly after impregnation intervals. Deltamethrin was extracted using acetone from samples and the extract was applied for spotting onto plates. The plates were developed with n-hexane: ethyl acetate, 90+10(v/v), as a mobile phase in a Camage chamber. The qualifying of residue was observed in UV cabinet with λ=254 nm wavelength. Data were analyzed using SPSS version 11.5. and Stata Version 8. A three way ANOVA was used to compare the means of deltamethrin residue in each area, group and measuring time. The Kruskal-Wallis test was used to compare the means of residue for each of these factors with the control separately.

RESULTS

The retardation factor of deltamethrin was calculated 0.50±0.02. The residues of deltamethrin persisted well on impregnated nets at least for 15 weeks after impregnation. No significant difference could be detected in the loss of residue of insecticide in comparison to measuring times and positions of sampling pieces on the bed nets in these areas.

CONCLUSION

Based on the results of the present study the use of HPTLC technique is recommended instead of other chromatographic methods for analysis of insecticide residue on the impregnated bed nets.

Distribution and ecology of mosquitoes in a focus of dirofilariasis in northwestern Iran, with the first finding of filarial larvae in naturally infected local mosquitoes

A study of the distribution and ecology of mosquitoes (Diptera: Culicidae) in Ardebil Province of northwestern Iran, with special reference to the known dirofilariasis focus in Meshkinshahr County, was carried out in July-August 2005 and April-October 2006. In total, 17,533 adult mosquitoes and 3090 third- and fourth-instar larvae were collected on 14 occasions and identified using morphological characters and DNA sequence data. Twenty species belonging to seven genera were found: Anopheles claviger (Meigen), An. hyrcanus (Pallas), An. maculipennis Meigen, An. pseudopictus Grassi*, An. sacharovi Favre, An. superpictus Grassi, Aedes vexans (Meigen)*, Coquillettidia richiardii (Ficalbi)*, Culex hortensis Ficalbi, Cx. modestus Ficalbi, Cx. pipiens Linnaeus, Cx. theileri Theobald, Cx. torrentium Martini*, Cx. tritaeniorhynchus Giles, Culiseta longiareolata (Macquart), Cs. annulata (Schrank)*, Cs. subochrea (Edwards), Ochlerotatus caspius (Pallas) s.l.* (= Aedes caspius sensu auctorum), Oc. geniculatus (Olivier)* (= Aedes geniculatus sensu auctorum) and Uranotaenia unguiculata Edwards (asterisks indicate new occurrence records for the province). The most prevalent species in adult catches were An. maculipennis (52%), Cx. theileri (45%) and Cx. hortensis (1%); the most prevalent species caught as larvae were Cx. theileri (27%), Cx. hortensis (21%) and An. maculipennis (19%). Anopheles maculipennis, Cx. pipiens and Cx. theileri were most widely distributed in the province. The occurrence of Cx. torrentium in Iran is verified based on differential characters of fourth-instar larvae. Anopheles maculipennis and An. sacharovi of the Maculipennis Group were identified from their diagnostic ITS2 sequences. For the first time, cytochrome c oxidase I (COI) sequences were obtained from Iranian specimens of An. hyrcanus, An. pseudopictus, Cx. theileri and Oc. caspiuss.l. Culex theileri and An. maculipennis were found naturally infected with third-stage (infective) larvae of Dirofilaria immitis (Leidy) and Setaria labiatopapillosa (Alessandrini) (Spirurida: Onchocercidae), respectively, for the first time in Iran.

First detection of Leishmania infantum in Phlebotomus (Larroussius) major (Diptera: Psychodidae) from Iran

Ghir-Karzin district is one of the most important endemic foci of visceral leishmaniaisis (VL) in Fars province of southern Iran. To identify the vector(s) of Leishmania in this focus, a total of 2,539 sand flies were collected during June to September 2005. Eleven species (six Phlebotomus and five Sergentomyia) were identified, of which Phlebotomus papatasi Scopoli and Phlebotomus major Annandale were the first (37.4%) and third (11.2%) most common species, respectively. Natural leptomonad infections were observed in two P. papatasi (4.25%) and three P. major (6.65%) specimens on dissection and microscopic examination. Using a Leishmania genus-specific standard polymerase chain reaction (PCR; primers RV1-RV2) and a species-specific nested-PCR (primers LINR4, LIN17, and LIN 19), Leishmania infantum and Leishmania major kinetoplast minicircle DNA was detected in 6 of 72 P. major (8.3%) and 4 of 65 P. papatasi (6.1%), respectively. This is the first detection of L. infantum in P. major, implicating this sand fly as a probable vector of VL in Iran.

Geographical variation in populations of Phlebotomus (Paraphlebotomus) caucasicus (Diptera: Psychodidae) in Iran

A comparative morphological and molecular study was carried out on 11 different populations of Phlebotomus (Paraphlebotomus) caucasicus Marzinovsky 1917 caught in 7 provinces in Iran (2004-2005). Differences in the implantation level of the two distal spines of the style, the number of setae of the basal lobe of coxite, and the length of the third antennal segment, revealed the existence of two morphotypes within P. (Pa) caucasicus, a species having a confused history if we take into account an unclear synonymisation with Phlebotomus (Paraphlebotomus) grimmi Porchinsky 1874. Sequencing of mtDNA (a fragment of cytchromeB gene, tRNA for serine gene and a fragment of NADH1 gene) and Neighbour-Joining analysis showed a partial correlation between morphotypes and haplotypes. We also found a correlation between the latter and the geographical origin of the specimens. These results need further studies in order to appreciate the role of each morphotype/haplotype in the transmission of Leishmania major.

Evaluation of deltamethrin-impregnated bed nets and curtains for control of zoonotic cutaneous leishmaniasis in a hyperendemic area of Iran

In the study carried out in the rural district of Borkhar (Isfahan, Iran) from March 2003 to March 2004 efficacy of deltamethrin impregnated bed nets (IBs) and curtains (ICs), polyester mesh size 156 holes/ inch2, (25 holes/cm2) were compared to that of non-impregnated bed nets (NIBs) and curtains (NICs), in relation to zoonotic cutaneous leishmaniasis (ZCL) control. Deltamethrin impregnated bed nets and curtains at 25 mg a.i./m2 were distributed among 168 households in one of the villages and NIBs plus NICs among the same number of households in another village. In the third village similar numbers of households were used as control. Health education messages were disseminated to ensure the population's compliance with the proper use of bed nets and curtains in the two intervention areas. Entomological surveys using sticky paper traps were carried out in ten households in each village for the collection of sand flies from indoors and outdoors, every two weeks to assess the impact of insecticide impregnated bed nets and curtains on the density of Phlebotomus papatasi. Deltamethrin susceptibility tests and also bioassay tests were carried out on this species by WHO standard method. Case findings were done by house-to-house visits once a season and all the inhabitants of the selected households in each village were examined. The results showed that IBs and ICs can provide a definite personal protection against sand fly bites and interrupted the transmission of ZCL in the intervention village. NIBs and NICs did not provide any protection against the disease. There was no significant difference in monthly density of P. papatasi in indoors and outdoors among the villages (P > 0.05). Susceptibility tests showed that this species was susceptible to deltamethrin in the field population in the area. Bioassays confirmed that the treated nets with deltamethrin remain effective for more than three months and was an excellent mean of individual protection. It is recommended that IBs and ICs can be used widely in the control of ZCL in other similar foci such as hyperendemic and mesoendemic areas of Iran.

Characterization of Leishmania infection in rodents from endemic areas of the Islamic Republic of Iran

Between 1991-2000, Leishmania species were isolated and characterized by isoenzyme and molecular analysis from rodents caught in various parts of the Islamic Republic of Iran. In areas endemic for cutaneous leishmaniasis, parasites were observed by direct microscopy in smears from 18.6% of 566 specimens. L. major was isolated from 4 species: Rhombomys opimus, Meriones libycus, Tatera indica and Mer. hurrianae. L. turanica was isolated from R. opimus for the first time in this country. In endemic areas of visceral leishmaniasis, parasites were observed in liver and spleen from 13.7% of 504 rodents. Two species were positive on culture; promastigotes isolated from Mer. persicus were characterized as L. donovani zymodeme LON50 and from Mesocricetus auratus as L. infantum LON49.

Epidemiological study in a new focus of cutaneous leishmaniasis in the Islamic Republic of Iran

An outbreak of cutaneous leishmaniasis (CL) in Sabzevar county prompted this study of the epidemiology and the ecology of vectors and reservoirs. Examination of 541 schoolchildren showed rates of 9.4% for scars and 5.9% for ulcers. Among 807 inhabitants of 4 villages, 10.4% had scars and 3.0% had active lesions. The most highly infected age group was 0-4 years with a rate of 5.9%. A total of 12 849 sandflies representing 7 species were collected in the study area. Leptomonad infection was found in Phlebotomus papatasi, P. caucasicus and Sergentomyia sintoni. Parasites from man, P. papatasi and Rhombomys opimus, were isolated and characterized as Leishmania major. Based on this survey, this is an epidemic of zoonotic CL, with R. opimus the main reservoir host, and P. papatasi the main vector.

Epidemiological study in a new focus of cutaneous leishmaniosis due to Leishmania major in Ardestan town, central Iran

An endemic focus of zoonotic cutaneous leishmaniosis caused by Leishmania major zymodeme MON-26 was identified in Ardestan town central Iran, during 1998-99. Among 1960 school children examined over a 1-year period of time, 0.92% had evidence of active lesions and 1.53% had scar indicative of past infection. The incidence of the disease among school children was 3.2 per thousand in 1998. In a separate study, the incidence of infection among 100 households in an area with a population of 460 persons showed 3.26% for scars and 1.3% for ulcers. The most highly infected age group was 10-14 with a rate of 2.74%. Meriones libycus (93.3%) and Nesokia indica (6.7%) were present around the town of Ardestan. Both were found to be infected with Leishmania. Two out of 28 M. libycus (7.1%) and one out of two N. indica had positive results. M. libycus is probably the principal reservoir host of zoonotic cutaneous leishmaniosis in this area. Fourteen dogs appeared to be uninfected because examination showed no active lesion or scar. Most probably Phlebotomus papatasi is the vector because about 93% of indoor sandflies were of this species. The active season of sandflies was from late May to late October. Economic changes in this area of Iran may have contributed to this outbreak of cutaneous leishmaniosis.

Bionomics of Anopheles sacharovi in Ardebil province, northwestern Iran during a larval control program

Studies were conducted on the ecology of Anopheles sacharovi over a period of 12 months in Parsabad and Germi counties, Ardebil province, Iran. The species was active from June to late November with one peak of activity in early August on the plain of Parsabad, and from late June to late November with one peak of activity in late August in mountainous areas of Germi. Chemical analysis of the water in larval habitats showed that the water contained calcium bicarbonate and sodium sulphate, and the limit of salinity was 263--414 mg/l. Dissection of A. sacharovi from three villages during July in Parsabad indicated a very low parity rates all were found negative for sporozoites. ELISA testing of 210 blood meals of the species, showed that few of those found in cowsheds or chicken coops had fed on humans, but of those found in bedrooms 38.5% had fed on humans. Insecticide susceptibility tests showed that the species is susceptible to malathion and propoxur but resistant to DDT and dieldrin.

Field trial for the control of zoonotic cutaneous leishmaniosis in Badrood, Iran

BACKGROUND

Due to the resurgence of zoonotic cutaneous leishmaniosis (ZCL) in some nonendemic areas of Iran, extensive studies have been conducted on the epidemiology of the disease in different parts of the country in recent years. The objective of this study was to determine the effects of rodent control on the reduction of the incidence of ZCL in an endemic area in Badrood, Iran.

PATIENTS AND METHODS

A survey was carried out in a circle around two villages between April 1997 and January 1999. The control strategy adopted in 1997 consisted of the destruction of the colonies of gerbilline rodents by digging in a radius of 500 m from houses in the intervention area. Opened burrows were baited with zinc phosphide. One village was used as control. Evaluation was made in 1998 and no other control measures were carried out in the area. Case findings were done by house-to-house visits once every season during 1997 and 1998, and all the inhabitants of the selected villages were examined.

RESULTS

The average reduction of rodent holes was calculated at 87.4% one year after the first baiting in the intervention area. Changes in the number of rodent holes and the incidence of the disease in the intervention and control villages were statistically significant (P-value <0.000001).

CONCLUSION

Our evaluation demonstrated that the control program reduced the incidence of ZCL 12-fold in the treated village compared to the control at the end of the first year of operation, and to more than one-fifth of its original level after two years. The results show that the field control method is very effective in destroying rodents and reducing the incidence of ZCL on a small scale and in special circumstances.

Entomological survey of sandflies (Diptera: Psychodidae) in a new focus of zoonotic cutaneous leishmaniosis in Iran

A total of 22,982 sandflies representing six species were collected using sticky (oiled) paper traps in Badrood rural district, Natanz county from May 1995 to May 1996. Phlebotomus papatasi was the predominant species. The average indoor resting density of P. papatasi ranged from 11.8 (May 1995) to 135.8 per 10 traps (September 1995). The average indoor resting density of this species varied between 39.7-701.3 per 10 traps in May and September, respectively in 1995. The activity of P. papatasi starts from late April or early May and extends to mid October with two peaks, one in mid or late June and the second one in early or mid September. Natural leptomonad infection was found in P. papatasi and Sergentomyia sintoni. P. papatasi could be a vector of humans and gerbils and it is susceptible to DDT in this area.

Studies on sandflies in a hyperendemic area of zoonotic cutaneous leishmaniasis in Iran

Ecological studies on sandflies were conducted in the Borkhar rural district, north of Isfahan in central Iran from March 1991 to March 1992. Sandflies were collected once every ten days from human dwellings and cattlesheds using sticky (oiled) paper traps. A total of 29004 sandflies were collected and seven species were identified. Phlebotomus papatasi predominated (83.8% in bedrooms and stables and 42.6% in rodent burrows) in the area. The average indoor resting density of P. papatasi ranged from 0.6 (October 1991) to 62.8 per 10 traps (August 1991). The average outdoor resting density of this species varied between 0.7-141.2 per 10 traps in November and July respectively in 1991. The activity of sandflies extended from end May to mid November. There were two peaks in the density curve of most species, one in June or July and the second in August or September. A significant positive correlation was observed between rainfall and relative density. Natural leptomonad infection was found in P. papatasi, P. caucasicus and P. ansarii, P. papatasi is the main vector to man, but P. caucasicus, P. mongolensis, P. ansarii and P. papatasi act as vectors among gerbils.

Meriones libycus and Rhombomys opimus (Rodentia: Gerbillidae) are the main reservoir hosts in a new focus of zoonotic cutaneous leishmaniasis in Iran

Following an epidemic of zoonotic cutaneous leishmaniasis (ZCL) around Badrood city, central Iran, Meriones libycus were found to be naturally infected with Leishmania major zymodeme MON-26 (= LON-1) in the villages of Matinabad and Fami, 12 km north-west of Badrood. This is the first isolation and characterization of L. major from M. libycus in Iran, in an area where ZCL has been present recently. M. libycus is probably the principal reservoir host in this area, but the main reservoir host further east is Rhombomys opimus. Parasites were not found in Hemiechinus auritis. The main, proven vector to humans and gerbils is Phlebotomus (Phlebotomus) papatasi. The close contact between vectors and reservoirs creates a very efficient cycle for the transmission of the disease.

Seasonal variation of Leishmania major infection rates in sandflies from rodent burrows in Isfahan province, Iran

In preparation for field trials of killed Leishmania major vaccine, natural infections with Leishmania promastigotes were monitored in Phlebotomine sandfly vectors from villages of Borkhar rural district, northeast of Isfahan in central Iran, where L.major zymodeme MON-26 ( = LON-1) has been identified as causing zoonotic cutaneous leishmaniasis (ZCL). Sandflies were collected and dissected weekly, from burrows of rodent colonies, during the "sandfly season', June-October 1991. Leptomonad infection rates were 12% of 26 Phlebotomus ansarii, 8% of 280 P.caucasicus, 11% of 1042 P.papatasi and none of 126 Sergentomyia sintoni, being greatest during late August through September, coinciding with peak activity of the sandflies, 2-3 months before the highest incidence of ZCL human cases in November-December.

Epidemiological study of reservoir hosts in an endemic area of zoonotic cutaneous leishmaniasis in Iran

The study was carried out in the central part of the Islamic Republic of Iran over a 12-month period in 1991-92 in Borkhar, a rural district lying north of Isfahan city. The objective was to determine the ecology of natural reservoir hosts of leishmaniasis for possible future field trials of leishmania vaccine. The main reservoir host in this area is Rhombomys opimus, the great gerbil, followed by Meriones libycus, the Libyan jird, and Hemiechinus auritis, the long-eared hedgehog. Of the 179 small mammals examined in the Borkhar area, the great majority were R. opimus (82.1%), then M. libycus (15.7%), and last H. auritis (2.2%). The highest rate of infection of R. opimus was in September (90.5%), the rate varying between 22.2% and 80.4% in different villages. The average infection rate of M. libycus was 17.9%. These rodents probably play an important role as reservoir hosts in the epidemiology of zoonotic cutaneous leishmaniasis in this area. Sixteen domestic and stray dogs appeared to be uninfected because examination showed no active lesion or scar.

Host preference pattern of phlebotomine sandflies of Borkhar rural district, Isfahan province, Iran

Blood meals from 400 engorged Phlebotomine sandflies belonging to three species collected in 6 villages from Borkhar rural district were identified by enzyme linked immunosorbent assay (ELISA). Out of 388 blood meals of Phlebotomus papatasi 29.6-44.6% were human blood, 8.4% dogs' blood and 0.6% cows' blood, indicating a strong preference for man. Double blood meals of human-dog and human-cow were observed in 0.9% and 3.08% P. papatasi respectively. Phlebotomus caucasicus was relatively anthropophilic and the human blood index in this species was 20%. Sergentomyia sintoni was negative for man and cow blood. Phlebotomus papatasi appears to be predominantly anthropophilic and makes the central part of Iran an area of high risk for leishmaniasis.

Leishmania major MON-26 isolated from naturally infected Phlebotomus papatasi (Diptera: Psychodidae) in Isfahan Province, Iran

In a survey of leishmania infections in phlebotomine sandflies in one of the most important focus of zoonotic cutaneous leishmaniasis (ZCL) at Borkhar, a rural district north of the city of Isfahan, central Iran, Phlebotomus (phlebotomus) papatasi Scopoli from gerbil and jird burrows were naturally infected with Leishmania major zymodeme MON-26. This is the first isolation and characterization of L. major from P. papatasi in Iran, from an area where human and rodent infections with L. major have been present for a very long time.

[Zoonotic cutaneous leishmaniasis to the north of Isfahan. Human infection in 1991]

An epidemiological investigation was carried out in 1991 at four villages in Borkhar rural district, north of Isfahan, Iran, to obtain baseline data for studying the candidate vaccines of zoonotic cutaneous leishmaniasis (ZCL). A study of prevalence among 6,284 inhabitants showed a rate of 61.95% for scars and 2.9% for active lesions. The under 10 years old showed a rate of 42.9% for scars and 7.5% for active lesions. The above 10 years old showed a rate of 71.06% for scars and 0.7% for active lesions. The highest prevalence of the disease is in the seasons of autumn and winter. The incidence of the disease was 68.4 per thousand in 1991. Comparing the results of this study with those from the years 1963-1965 showed that the disease incidence has increased after 28 years and ZCL has remained as an important health problem in this area.

The isolation of Leishmania major from Phlebotomus (Paraphlebotomus) caucasicus, in Isfahan province, Islamic Republic of Iran

As part of a general survey of leishmaniasis and sandflies in the focus of zoonotic cutaneous leishmaniasis (ZCL) at Borkhar, a rural district north of the city of Isfahan, central Iran, Phlebotomus (Paraphlebotomus) caucasicus Marzinowsky from gerbil and jird burrows were found naturally infected with Leishmania major, zymodeme MON-26 (= LON-1). This is the first characterized isolate of L. major from a sandfly vector in Iran.