Impact of phlebotomine sand flies on United States military operations at Tallil Air Base, Iraq: 5. Impact of weather on sand fly activity.

In this study, we examined the effect of weather and moon illumination on sand fly activity, as measured by light trap collections made between 2 May 2003 and 25 October 2004 at Tallil Air Base, Iraq. Wind speed, temperature, dew point, percentage of sky cover, and moon illumination were entered into principal components analysis. The resulting principal components were entered into stepwise regression to develop a model of the impact of the weather on sand fly collections. Wind speed, percentage of sky cover, and moon illumination each had a strong inverse relationship with the number of sand flies collected, whereas temperature displayed a direct relationship to sand fly collections. Our data indicate that sand fly light trap catches at Tallil Air Base are highest on warm, clear nights with low wind speed and minimal illumination from the moon.

Impact of phlebotomine sand flies on United State military operations at Tallil Air Base, Iraq: 6. Evaluation of insecticides for the control of sand flies.

We conducted a series of field experiments in 2003 and 2004 to evaluate the efficacy of a variety of insecticides and insecticide application technologies for the control of phlebotomine sand flies at Tallil Airbase, Iraq. During the experiments, 53,263 sand flies were collected. The experiments evaluated the following: (1) routine sand fly control operations using a variety of residual and area-wide insecticides; (2) a combination of five different insecticide application methods in and around tents; (3) residual application of lambda-cyhalothrin and ultra-low volume application of pyrethrins in houses; (4) carbaryl and lambda-cyhalothrin applied as barrier sprays; (5) a deltamethrin-impregnated fence; (6) lambda-cyhalothrin applied as a residual spray in concrete manholes; (7) deltamethrin-treated flooring in tents; and 8) ultra-low volume-applied malathion. Although some of the experiments resulted in limited reductions in the number of sand flies collected in light traps, in no instance did we completely eliminate sand flies or reduce populations for a sustained period. The implications of these findings are discussed.

Serological surveillance of scrub typhus, murine typhus, and leptospirosis in small mammals captured at firing points 10 and 60, Gyeonggi province, Republic of Korea, 2001-2005.

Soldiers from the Republic of Korea and the United States conducting peacetime military operations at various training sites and multiple range complexes located near the demilitarized zone separating North and South Korea are exposed to rodents and their potentially disease-carrying ectoparasites. These diseases include scrub typhus, murine typhus, and leptospirosis. Many of the training sites are rural or semi-rural, surrounded or co-located with various forms of agriculture, and are infested with rodents and insectivores (as well as their ectoparasites), which are commonly found in association with unmanaged tall grasses, scrub, and crawling vegetation habitats. For 5 years, rodents and insectivores were collected seasonally (spring, summer, fall, and winter) at firing points 10 and 60 near the demilitarized zone and serologically tested for the presence of scrub typhus, murine typhus, and leptospirosis antibodies. Of the nine species of small mammals collected, Apodemus agrarius, the common striped field mouse and known reservoir of scrub typhus, was the most frequently collected (90.6%). Only four of the nine species captured, A. agrarius (60.9%), Micromys minutus (100%), Mus musculus (55.6%), and Rattus norvegicus (46.7%), were positive for scrub typhus. Of all the small mammals captured, only A. agrarius was positive for murine typhus (0.3%) and leptospirosis (1.3%). Seasonal and annual prevalence rates based on weight and sex are presented.

Efficiency evaluation of Nozawa-style black light trap for control of anopheline mosquitoes.

House-residual spraying and insecticide-treated bed nets have achieved some success in controlling anthropophilic and endophagic vectors. However, these methods have relatively low efficacy in Korea because Anopheles sinensis, the primary malaria vector, is highly zoophilic and exophilic. So, we focused our vector control efforts within livestock enclosures using ultraviolet black light traps as a mechanical control measure. We found that black light traps captured significantly more mosquitoes at 2 and 2.5 m above the ground (P < 0.05). We also evaluated the effectiveness of trap spacing within the livestock enclosure. In general, traps spaced between 4 and 7 m apart captured mosquitoes more efficiently than those spaced closer together (P > 0.05). Based on these findings, we concluded that each black light trap in the livestock enclosures killed 7,586 female mosquitoes per trap per night during the peak mosquito season (July-August). In May-August 2003, additional concurrent field trials were conducted in Ganghwa county. We got 74.9% reduction (P < 0.05) of An. sinensis in human dwellings and 61.5% reduction (P > 0.05) in the livestock enclosures. The black light trap operation in the livestock enclosures proved to be an effective control method and should be incorporated into existing control strategies in developed countries.

Ecological surveillance of small mammals at Firing Points 10 and 60, Gyeonggi Province, Republic of Korea, 2001-2005.

Throughout Korea, small mammals are hosts to a number of disease-causing agents that pose a health threat to U.S. and Korean military forces while they conduct field-training exercises. A seasonal rodent-borne disease surveillance program was established at two firing points (FP), FP-10, and FP-60, and conducted over five years from 2001 through 2005 in response to hantavirus cases among U.S. soldiers. The ecology of these sites consisted primarily of tall grasses associated with semi-permanent and temporary water sources (drainage ditches and a small stream) and dry-land agriculture farming. Eight species of rodents and one species of insectivore were collected, including Apodemus agrarius, Micromys minutus, Mus musculus, Rattus norvegicus, Tscherskia triton, Microtus fortis, Myodes regulus, and Crocidura lasiura. The striped field mouse, A. agrarius, (primary reservoir for Hantaan virus, the causative agent of Korean hemorrhagic fever), was the most frequently collected, representing 90.6% of the 1,288 small mammals captured at both sites. Reported herein are the ecological parameters, seasonal population densities, and seasonal population characteristics associated with small mammals collected at two military training sites in the Republic of Korea.

Impact of phlebotomine sand flies on U.S. military operations at Tallil Air Base, Iraq: 3. Evaluation of surveillance devices for the collection of adult sand flies.

We evaluated the effectiveness of commercially available light traps and sticky traps baited with chemical light sticks for the collection of phlebotomine sand flies. Evaluations were conducted at Tallil Air Base, Iraq, in 2003. In an initial study, a Centers for Disease Control and Prevention (CDC)-style trap with UV bulb collected significantly more sand flies than did an up-draft CDC trap, a standard down-draft CDC trap (STD-CDC), or a sticky strap with a green chemical light stick. In a subsequent study, we found that the addition of chemical light sticks to sticky traps resulted in a significant increase in the number of sand flies collected compared with sticky traps without the light sticks. These data indicate that 1) the CDC light trap with an UV bulb is an effective alternative to the standard CDC light trap for collecting phlebotomine sand flies in Iraq, and 2) that the addition of a chemical light stick to a sticky trap can result in a field-expedient tool for the collection of sand flies.

Impact of phlebotomine sand flies on U.S. Military operations at Tallil Air Base, Iraq: 2. Temporal and geographic distribution of sand flies.

CDC miniature light traps were used to evaluate the general biology of phlebotomine sand flies from April 2003 to November 2004 at Tallil Air Base, Iraq. Factors evaluated include species diversity and temporal (daily and seasonal) and geographic distribution of the sand flies. In addition, the abundance of sand flies inside and outside tents and buildings was observed. In total, 61,630 sand flies were collected during 1,174 trap nights (mean 52 per trap, range 0-1,161), with 90% of traps containing sand flies. Sand fly numbers were low in April, rose through May, were highest from mid-June to early September, and dropped rapidly in late September and October. More than 70% of the sand flies were female, and of these sand flies, 8% contained visible blood. Phlebotomus alexandri Sinton, Phlebotomus papatasi Scopoli, Phlebotomus sergenti Parrot, and Sergentomyia spp. accounted for 30, 24, 1, and 45% of the sand flies that were identified, respectively. P. alexandri was more abundant earlier in the season (April and May) than P. papatasi, whereas P. papatasi predominated later in the season (August and September). Studies on the nocturnal activity of sand flies indicated that they were most active early in the evening during the cooler months, whereas they were more active in the middle of the night during the hotter months. Light traps placed inside tents with and without air conditioners collected 83 and 70% fewer sand flies, respectively, than did light traps placed outside the tents. The implications of these findings to Leishmania transmission in the vicinity of Tallil Air Base are discussed.

Study of flying height of culicid species in the northern part of the Republic of Korea.

The vertical distribution of mosquitoes (Diptera, Culicidae) was evaluated in Paju County in northern South Korea by using Centers for Disease Control and Prevention (CDC) miniature light traps with ultraviolet light and dry ice (CO2) as attractants. CDC traps were placed at 1, 3 and 5 m above the ground near rice paddies in a relatively open agricultural ara. Traps wer hung on two scaffold towers (6 m height) spaced approximately 300 m aprt. Each trap operated 9 nights from August 3 to 16, 2002, and collected 9,971 mosquitoes: Aedes Vexans nipponii, 145.2; Culex tritaeniorhynchus, 34.9; Anopheles sinensis, 21.3; and Culex pipiens, 17.3 female mosquitoes/trap/night. Average flight height was calculated from the total number of catches in both stations. Overall, Cx. pipiens (2.52 +/- 0.35 m) was found to be the highest flying species followed by An. sinensis (2.04 +/- 0.79 m), Ae. vexans nipponii (1.96 +/- 0.44 m), and Cx. tritaeniorhynchus (1.76 +/- 0.68 m), respectively. Although no significant difference in flying height among species was encountered, every species showed their own flight preference range, matching with their host preference.

Impact of phlebotomine sand flies on U.S. Military operations at Tallil Air Base, Iraq: 1. background, military situation, and development of a "Leishmaniasis Control Program".

One of the most significant modern day efforts to prevent and control an arthropod-borne disease during a military deployment occurred when a team of U.S. military entomologists led efforts to characterize, prevent, and control leishmaniasis at Tallil Air Base (TAB), Iraq, during Operation Iraqi Freedom. Soon after arriving at TAB on 22 March 2003, military entomologists determined that 1) high numbers of sand flies were present at TAB, 2) individual soldiers were receiving many sand fly bites in a single night, and 3) Leishmania parasites were present in 1.5% of the female sand flies as determined using a real-time (fluorogenic) Leishmania-generic polymerase chain reaction assay. The rapid determination that leishmaniasis was a specific threat in this area allowed for the establishment of a comprehensive Leishmaniasis Control Program (LCP) over 5 mo before the first case of leishmaniasis was confirmed in a U.S. soldier deployed to Iraq. The LCP had four components: 1) risk assessment, 2) enhancement of use of personal protective measures by all personnel at TAB, 3) vector and reservoir control, and 4) education of military personnel about sand flies and leishmaniasis. The establishment of the LCP at TAB before the onset of any human disease conclusively demonstrated that entomologists can play a critical role during military deployments.

Commercial mosquito trap and gravid trap oviposition media evaluation, Atlanta, Georgia.

Field trials evaluating the effectiveness of selected gravid trap oviposition media and commercially available mosquito traps were conducted in southern Fulton County (Atlanta), GA, from June 9 to June 18 and June 24 to July 4, 2002, respectively. Total number of mosquitoes and number of each species captured during the tests were compared using a Latin square design. For the gravid trap infusion media, significant differences were found for total number of mosquitoes collected where sod > or = hay > or = hay side-by-side diluted hay > dilute hay side-by-side hay > or = oak > diluted hay. Only Aedes albopictus (oak), Culex quinquefasciatus (sod and both concentrated hay infusions), and Culex restuans (sod) were captured in significantly greater numbers using a particular infusion. Significant differences for the total number of mosquitoes collected were also observed in the commercial mosquito traps such that the gravid trap > ultra violet up-draft > or = Mosquito Magnet Pro > or = omnidirectional Fay-Prince trap with CO2 > up-draft CDC-style with CO2 > or = CDC-style with CO2. Significant differences in numbers collected among traps were noted for several species, including Aedes vexans, Aedes albopictus, Cx. quinquefasciatus, Cx. restuans, and Culex salinarius. Results from these field trap and infusion evaluations can enhance current surveillance efforts, especially for the primary vectors of West Nile virus and other arboviruses.

Evaluation of candidate traps as tools for conducting surveillance for Anopheles mosquitoes in a malaria-endemic area in western Thailand.

The effectiveness of five mosquito traps at sampling anopheline mosquitoes was compared with landing/biting (L/B) collections in western Thailand. Traps evaluated included a CDC style light trap (CDC LT) with dry ice, the American Biophysics Corporation (ABC) standard light trap (ABC LT) with dry ice and octenol, the ABC counterflow geometry (CFG) trap with dry ice and octenol, the ABC mosquito magnet (MM) trap with octenol, and the Nicosia and Reinhardt Company Mosquito Attractor Device (N&R trap). Mosquito numbers captured in landing-biting collections were 5.2, 7.0, 7.3, 31.1, and 168.8 times greater than those collected in the ABC LT, MM, CDC LT, CFG, and N&R traps, respectively, for Anopheles minimus Theobald, the predominant malaria vector in the region. Similar results were obtained for the secondary malaria vectors Anopheles maculatus Theobald and Anopheles sawadwongporni Rattanarithikul & Green. Only Anopheles kochi Doenitz was collected in significantly greater numbers in the CDC LT, ABC LT, and MM traps compared with L/B collections. Although none of the traps were as effective as L/B collections, the ABC LT, MM, and CDC LT were the best alternatives to human bait for the collection of anopheline malaria vectors in Thailand.

Isolation of Japanese encephalitis and Getah viruses from mosquitoes (Diptera: Culicidae) collected near Camp Greaves, Gyonggi Province, Republic of Korea, 2000.

As part of an evaluation of the ecology of arthropod-borne diseases in the Republic of Korea (ROK), we examined 8,765 mosquitoes captured in Paju County, Gyonggi Province, ROK, for the presence of viruses. Mosquitoes were captured in propane lantern/human-baited Shannon traps, Mosquito Magnet traps, or American Biophysics Corporation (East Greenwich, RI) miniature light traps with or without supplemental octenol bait and/or dry ice. Mosquitoes were identified to species, placed in pools of up to 40 mosquitoes each, and tested on Vero cells for the presence of virus. A total of 15 virus isolations were made from 293 pools of mosquitoes. Viruses were identified by reverse transcriptase-polymerase chain reaction and sequencing and consisted of 14 isolations of Japanese encephalitis (JE) virus and one isolation of Getah (GET) virus. All JE isolates were from Culex tritaeniorhynchus Giles, and the isolate of GET was from Aedes vexans (Meigen). The minimum field infection rate for JE in Cx. tritaeniorhynchus was 3.3 per 1,000, whereas the GET virus infection rate for Ae. vexans was 0.2 per 1,000. Isolation of JE and GET indicated that both viruses were actively circulating in northern Gyonggi Province, ROK. The lack of human cases of JE among the Korean population probably is because of an effective government-mandated vaccination program. The reason for no cases among >10,000 United States military and others that reside or train nearby is unknown, but may be related to personnel protection measures (permethrin-impregnated uniforms and use of deet repellent), adult mosquito control, mosquito selection of nonhuman hosts (unpublished data), and the low symptomatic to asymptomatic ratio of disease in adults.

Evaluation of anopheline mosquitoes (Diptera: Culicidae) from the republic of Korea for Plasmodium vivax circumsporozoite protein.

As part of an on-going malaria surveillance effort conducted by the U.S. Forces Korea, Republic of Korea (ROK), a total of 28,286 anopheline mosquitoes was tested for the presence of Plasmodium vivax circumsporozoite (CS) protein. Mosquitoes were collected (using a variety of light and baited traps) from 29 locations throughout the ROK (the majority were collected near the de-militarized zone), identified to species, and tested by enzyme-linked immunosorbent assay for the presence of P. vivax 210 and P. vivax 247 CS protein. Recent evidence suggests that characters used to separate Anopheles sinensis Wiedemann from An. lesteri Baisas & Hu are unreliable; therefore, the data have been analyzed by grouping these two species. A total of 25,365 Anopheles sinensis/lesteri, 2,890 An. yatsushiroensis Miyazaki, and 31 An. sineroides Yamada was tested. Of these, one pool of 10 An. sinensis/lesteri collected on 9 September 1999 at Camp Howze and one pool of nine An. sinensis/ lesteri collected on 13 September 1999 at Camp Bonifas were positive for P. vivax 247.

Late season commercial mosquito trap and host seeking activity evaluation against mosquitoes in a malarious area of the Republic of Korea.

Field trials evaluating selected commercially available mosquito traps variously baited with light, carbon dioxide, and/or octenol were conducted from 18-27 September 2000 in a malarious area near Paekyeon-ri (Tongil-Chon) and Camp Greaves in Paju County, Kyonggi Province, Republic of Korea. The host-seeking activity for common mosquito species, including the primary vector of Japanese encephalitis, Culex tritaeniorhynchus Giles, was determined using hourly aspirator collections from a human and propane lantern-baited Shannon trap during hours when temperatures exceeded 15 degrees C. The total number of mosquitoes and number of each species captured during the test was compared using a block design. Significant differences were observed for the total number of mosquitoes collected, such that, the Mosquito MagnetTM with octenol > Shannon trap > ABC light trap with light and dry ice > Miniature Black Light trap (manufactured by John W. Hock) > or = New Jersey Trap > ABC light trap with light only. Significant differences in numbers collected among traps were noted for several species including: Aedes vexans (Meigen), Anopheles lesteri Baisas and Hu. An. sinensis Weidemann. An. sineroides Yamada, An. yatsushiroensis Miyazaki, Culex pipiens pallens Coquillett L., Cx. orientalis Edwards and Cx. tritaeniorhynchus. Host-seeking activity for most common species showed a similar bimodal pattern. Results from these field trap evaluations can significantly enhance current vector and disease surveillance efforts especially for the primary vector of Japanese encephalitis, Cx. tritaeniorhynchus.