Potential for the Invasive Species Aedes Albopictus and Arboviral Transmission through the Chabahar Port in Iran.

BACKGROUND: Dengue, chikungunya, and Zika viruses are emerging infectious disease threats wherever suitable vectors, hosts, and habitat are present. The aim of the present study was to use the bioagent transport and environmental modeling system (BioTEMS) to identify the potential for arbovirus-infected Aedes species to invade the Chabahar area in southeastern Iran. METHODS: ArcGIS geospatial analysis software, Statistica software, and BioTEMS were used to analyze geographic information and conduct data analysis. BioTEMS utilizes up to several hundred abiotic and biotic factors to produce risk and vulnerability assessments for biological agents and infectious diseases. The output of BioTEMS was validated using published predictive models, and most importantly published collection data of Aedes species in Iran. RESULTS: There appears to have been two separate invasion events by Ae. albopictus into the southern region of Iran, first preceding 2009 and then again in 2013. BioTEMS identified two probable areas of introduction during the 2009 time frame, either through one or both the Chabahar ports or the Iranshahr airport with subsequent spread through vehicular transport. BioTEMS identified the port as an introduction zone for ZIKAV with high-risk zones and identifies gap zones during the 2013 time frame. Recommended surveillance sites are provided. CONCLUSION: The air and maritime ports of Iran serve international customers, and are therefore vulnerable to import and invasion of mosquito vectors and arboviruses. Based on comparisons with other published low-resolution models, BioTEMS provides information for medical and public health professionals conducting integrated mosquito management, preventive medicine, and epidemiological surveillance.

Assessing likely invasion sites of Zika virus-infected mosquitoes in civilian and naval maritime ports in Florida.

Several mosquito species are capable of invading new geographic regions and exploiting niches that are similar to their natural home ranges where they may introduce, or reintroduce, pathogens. In addition to initial invasion, introduction of new genotypes into established populations may also occur. Zika virus is spreading throughout the world, posing significant health risks to human populations, particularly pregnant women and their infants. The first locally acquired case of Zika virus in the US occurred in July 2016 in Miami, Florida on the Atlantic coast; the first locally acquired case in another US county occurred in the Tampa, Florida area. Three port cities in Florida were chosen to assess the risk of import and spread of Zika virus: Mayport Naval Station, Miami, and Tampa. The bioagent transport and enviromental modeling system TIGER model and ArcGIS were used to analyze abiotic and biotic factors influencing potentially Zika-infected Aedes species, should they enter through these ports. The model was tested by overlaying documented and suspected concurrent Zika cases and comparing published high-risk areas for Zika virus. In addition to Zika hot zones being identified, output indicates surveillance and integrated mosquito management should expect larger zones. Surveillance sites at ports should be identified and prioritized for pathogen and vector control to reduce the import of mosquitoes infected with Zika virus. Low resolution maps often provide valuable suitability of the geographic expansion of organisms. Providing a higher resolution predictive map, identifying probable routes of invasion, and providing areas at high risk for initial invasion and control zones, will aid in controlling and perhaps eliminating the spread of arboviruses through mosquito vectors.

Preliminary Report on the Reduction of Adult Mosquitoes in Housing Compounds in Western Kenya Using the ProVector Flower and Entobac Bait Pads Containing Bacillus thuringiensis israelensis With Honey Bait.

Reducing mosquito populations indoors and outdoors can have a significant impact on malaria and other mosquito-borne diseases. A new formulation and delivery system for Bacillus thuringiensis israelensis (Bti) was tested against adult mosquitoes. One Entobac bait with 7% Bti in a honey solution was placed within each ProVector Flower applicator. The applicators were placed in nine housing compounds, one on the outside of each home in Ahero and Nyalenda, Kenya, in June 2009. Seven housing compounds with no applicators were included as controls in the study area. After 1 mo, there was a significant reduction of mosquitoes in all nine compounds with the ProVector Flower compared to two of the seven control compounds. The overall mosquito population was reduced by 69% in housing compounds with the ProVector Flower whereas the mosquito population grew by nearly 15% in the control compounds. There was a significant reduction of the median number of mosquitoes in the test compounds than in the control compounds. The proportion of mosquitoes collected was significantly reduced in the test compounds within 1 mo for several species of Aedes, Anopheles, Coquillettidia, Culex, and Mansonia. This study provides evidence that Bti-laced bait may be used as an alternative adulticide and be delivered in an applicator to reduce mosquito populations of several species. This method may significantly reduce the cost of pesticide application through target specificity and by reducing the amount of pesticide placed into the environment.

Seasonal distribution of ticks in four habitats near the demilitarized zone, Gyeonggi-do (Province), Republic of Korea.

This study describes the seasonal distribution of larvae, nymph, and adult life stages for 3 species of ixodid ticks collected by tick drag and sweep methods from various habitats in the Republic of Korea (ROK). Grasses less than 0.5 m in height, including herbaceous and crawling vegetation, and deciduous, conifer, and mixed forests with abundant leaf/needle litter were surveyed at United States (US) and ROK operated military training sites and privately owned lands near the demilitarized zone from April-October, 2004 and 2005. Haemaphysalis longicornis Neumann adults and nymphs were more frequently collected from April-August, while those of Haemaphysalis flava Neumann and Ixodes nipponensis Kitaoka and Saito were collected more frequently from April-July and again during October. H. longicornis was the most frequently collected tick in grass habitats (98.9%), while H. flava was more frequently collected in deciduous (60.2%) and conifer (57.4%) forest habitats. While more H. flava (54.1%) were collected in mixed forest habitats than H. longicornis (35.2%), the differences were not significant. I. nipponensis was more frequently collected from conifer (mean 8.8) compared to deciduous (3.2) and mixed (2.4) forests.

Comparison of dragging and sweeping methods for collecting ticks and determining their seasonal distributions for various habitats, Gyeonggi Province, Republic of Korea.

As part of the 65th Medical Brigade tick-borne disease surveillance program to determine the abundance, geographical and seasonal distributions, and tick-borne pathogens present in the Republic of Korea, dragging and sweeping methods were compared to determine their efficiency for collecting ticks in grass and deciduous, conifer, and mixed forest habitats at military training sites and privately owned lands in northern Gyeonggi Province near the demilitarized zone from April-October, 2004-2005. Three species of Ixodid ticks, Haemaphysalis longicornis, Haemaphysalis flava, and Ixodes nipponensis, were collected. Overall, H. longicornis adults and nymphs were most frequently collected from grass and deciduous forest habitats, accounting for 98.2 and 66.2%, respectively, of all ticks collected. H. flava adults and nymphs were most frequently collected from conifer and mixed forests, accounting for 81.6, and 77.8%, respectively, of all ticks collected. I. nipponensis adults and nymphs accounted for 9.3% of all ticks collected from mixed forests, were less commonly collected from deciduous (4.1%) and conifer (4.1%) forests, and infrequently collected from grass habitats (0.9%). Overall, there were no significant differences between dragging and sweeping methods for the three species when the areas sampled were similar (sweeping = 2 x the area over the same transect). Adults and nymphs of H. longicornis were most commonly collected from April-August, while those of H. flava and I. nipponensis were most commonly collected during April-July and again during October. Larvae of all three species were most frequently observed from July-September.

Variation of circumsporozoite 26 and 29 genotypes of Plasmodium falciparum infecting patients and association with HLA-DQA allotypes in western Thailand.

We evaluated the proportion of variants of circumsporozoite protein (cp) gene 26 and cp29 antigenic epitopes of Plasmodium falciparum infecting patients among 3 provinces in western Thailand, in addition to published variants from Gambia. The proportion of patients coinfected with cp26 and cp29 strains was significantly higher in patients reporting to malaria clinics in Tak than in Kanchanaburi and Ratchaburi and higher in Kanchanaburi than in Ratchaburi. In western Thailand, coinfection with cp26 and cp29 appears to increase with increasing latitude. There were also significant differences in proportion of these variants among Thai provinces and Gambia. An association of patient human leukocyte antigen (HLA) class II genotype was associated with P. falciparum strains. There were significant associations among the HLA-DQA alleles in patients, the province of origin, and cp variants of P. falciparum.

Occurrence of Orientia tsutsugamushi in small mammals from Thailand.

Extensive sampling of small mammals was conducted in eight provinces of Thailand between September 9, 1992 and April 29, 2001. A total of 3,498 specimens representing 22 species were collected. Eighty-eight percent (3,089 of 3,498) of the animals were collected from a region in Chiangrai Province, which is commonly recognized as endemic for human scrub typhus. Blood and tissue samples from each animal were tested for the presence of Orientia tsutsugamushi, the etiologic agent of scrub typhus. The predominant species collected were Rattus rattus (53%, n = 1,863), R. losea (18%, n = 638), Bandicota indica (16%, n = 564), and R. exulans (4%, n = 146). Orientia tsutsugamushi was detected in 10 of the 22 species of mammals that included R. bukit (25% infected, 1 of 4), R. rattus (23%, 419 of 1,855), R. argentiventer (22%, 5 of 23), R. berdmorei (22%, 2 of 9), R. losea (13%, 82 of 638), B. indica (9%, 52 of 564), R. koratensis (8%, 1 of 12), B. savilei (3%, 1 of 30), R. exulans (1%, 2 of 146), and Tupaia glis (2%, 1 of 49). Infected animals were found in Chiangrai (18% infected, 563 of 3,084), Bangkok (11%, 1 of 9), Sukothai (3%, 1 of 30), and Nonthaburi (1%, 1 of 69) Provinces. The implications towards scrub typhus maintenance and transmission are discussed.

Evidence of Borrelia lonestari DNA in Amblyomma americanum (Acari: Ixodidae) removed from humans.

We used a nested PCR with Borrelia flagellin gene (flaB) primers and DNA sequencing to determine if Borrelia lonestari was present in Amblyomma americanum ticks removed from military personnel and sent to the Tick-Borne Disease Laboratory of the U.S. Army Center for Health Promotion and Preventive Medicine. In our preliminary investigation, we detected Borrelia sequences in 19 of 510 A. americanum adults and nymphs from Ft. A. P. Hill, Va. During the 2001 tick season, the flaB primers were used to test all A. americanum samples as they were received, and 29 of 2,358 A. americanum samples tested individually or in small pools were positive. PCRs with 2,146 A. americanum samples in 2002 yielded 26 more Borrelia-positive samples. The positive ticks in 2001 and 2002 were from Arkansas, Delaware, Kansas, Kentucky, Maryland, New Jersey, North Carolina, Tennessee, and Virginia. The last positive sample of the 2001 season was a pool of larvae. To further investigate larval infection, we collected and tested questing A. americanum larvae from Aberdeen Proving Ground, Md.; 4 of 33 pools (40 larvae per pool) were positive. Infection of unfed larvae provides evidence of the maintenance of B. lonestari by means of transovarial transmission. Sequence analysis revealed that the amplicons were identical to sequences of the B. lonestari flaB gene in GenBank. Despite the low prevalence of infection, the risk of B. lonestari transmission may be magnified because A. americanum is often abundant and aggressive, and many tick bite victims receive multiple bites.

Short report: variation in the 56-kD type-specific antigen gene of Orientia tsutsugamushi isolated from patients in Thailand.

The sequences of a 300-base pair region of the 56-kD type-specific antigen gene from 12 Orientia tsutsugamushi isolates from Thailand were compared with isolates from other regions in Asia. A high degree of heterogeneity was found among the 12 Thai isolates, with the C3 strain most commonly found. The abundance of the C3 strain of O. tsutsugamushi is of particular concern because doxycycline and chloramphenicol resistance have previously been reported in this strain.

Host associations and seasonal occurrence of Haemaphysalis leporispalustris, Ixodes brunneus, I. cookei, I. dentatus, and I. texanus (Acari: Ixodidae) in Southeastern Missouri.

Hemaphysalis leporispalustris (Packard), Ixodes brunneus Koch, Ixodes cookei Packard, Ixodes dentatus Marx, and Ixodes texanus Banks were collected during a 3-yr study of pathogen-tick-host interactions in southeastern Missouri. H. leporispalustris was collected from the eastern cottontail rabbit, Northern bobwhite, and Carolina wren, and it was active all year. I. brunneus was collected by drag and from passerine birds during December, March, and April. I. cookei was collected from raccoons and mink during April, June, September, October, and November. I. dentatus was collected from the cottontail rabbit and Carolina wren throughout the year. I. texanus was collected from the eastern gray squirrel, Virginia opossum, and raccoon throughout the year.

Efficiency of Leptotrombidium chiggers (Acari: Trombiculidae) at transmitting Orientia tsutsugamushi to laboratory mice.

Thirteen different laboratory colonies of Leptotrombidim chiggers [L. chiangraiensis Tanskul & Linthicum, L. deliense Walch and L. imphalum (Vercammen-Grandjean &Langston)] were evaluated for their ability to transmit Orientia tsutsugamushi (Hyashi) to mice. Of 4,372 transmission attempts using individual chiggers from all 13 colonies, 75% (n = 3,275) successfully infected mice. Transmission rates for the individual chigger colonies ranged from 7 to 80%. Increasing the number of chiggers that fed on a given mouse generally increased transmission rates. Transmission of O. tsutsugamushi to mice by different generations (F1-F11) of certain chigger colonies was stable; however, transmission rates varied greatly in other colonies. Transmission rates (both vertical and horizontal) of several L. changraiensis colonies and the L. deliense colony were the highest, suggesting that these colonies may be useful for the development of a chigger-challenge model that can be used to evaluate the efficacy of candidate scrub typhus vaccines or therapeutic agents in laboratory mice.

Antibodies to leptospirosis in rodents from Thailand using a modified human diagnostic assay.

The number of reported cases of Leptospirosis in Thailand has grown since 1996. Identification of major reservoirs and endemic areas is essential in surveillance of Leptospira species in Thailand. To assist in the effort of surveillance, a dipstick assay for detecting Leptospira antibodies in mammals was adapted from a human diagnostic assay and tested in a field trial in Thailand. Antibodies to Leptospira were detected in 18 of 60 wild rodents. Four of 9 culture positive rodents were positive by the dipstick assay. The proportion of sera positive for antibodies by dipstick was correlated with positive culture outcome using McNemar test for correlated proportions (0.83, P> 0.05). The dipstick assay was effective in detecting antibodies to Leptospira in mammals and may be useful in resource poor areas or under circumstances where the microagglutination test (MAT) is not practical.