New record of Phlebotomus sergenti, the vector of Leishmania tropica, in the southern Nile valley of Egypt.

We report the 1st collection of Phlebotomus sergenti, a vector of the cutaneous and visceralizing forms of Leishmania tropica, from southern Egypt. Four female and 1 male P. sergenti were collected from unlit Centers for Disease Control light traps placed in a village on the Nile River, 6 km north of Aswan, Egypt, during studies conducted from 1998 to 1999. This extends the known distribution of this species farther south in Egypt than previously recorded.

Perceptions of veterinary clinics and pest control companies regarding tick-related problems in dogs residing in Texas cities.

OBJECTIVE: To determine the extent and source of tick-related problems encountered by veterinary clinics and pest control company (PCC) clientele experiencing residential tick infestations in urban/suburban environments and to determine which tick-related diseases in dogs were diagnosed and treated at veterinary clinics. DESIGN: Cross-sectional survey. SAMPLE POPULATION: Veterinary clinics and PCC in Dallas/Fort Worth and Austin/San Antonio, Tex. PROCEDURE: Surveys were made into professionally printed booklets and mailed to participants. RESULTS: Dallas/Fort Worth and Austin/San Antonio clinics indicated that tick-related problems comprised 21 and 15%, respectively, of their canine-based business. The most frequently observed species was the brown dog tick. Tick infestations were most common during May through August. Immature tick populations were seen by the greatest number of clinics in May and June, and engorged female ticks were encountered most often in June and July. Ticks were most commonly found around homes and adjacent yards or lots. Greenbelts were perceived by all 4 study groups to be the principal place in the community where ticks were acquired by clients' dogs. Canine ehrlichiosis was the most common tick-related disease diagnosed and treated at clinics, followed by anemia caused by tick infestation. CLINICAL IMPLICATIONS: Identification of ticks is important, because different tick species transmit different disease agents and different ecologic factors may be associated with exposure and subsequent treatment. Knowledge of temporal activity patterns of ticks, where they are acquired and where populations become established, combined with improved cooperative efforts between veterinary clinics and PCC, would aid in more effective control and management of ticks.

Rift Valley fever in rural northern Senegal: human risk factors and potential vectors.

To investigate past infection in and transmission of Rift Valley fever (RVF) virus to humans within an endemic focus, we undertook a retrospective cohort study of the seminomadic Peul people living in sub-Saharan northcentral Senegal. Residents of the rural settlement of Yonofere five years of age or older were studied during February-May 1989. Anti-RVF virus IgG was found in blood samples of 22.3% of 273 persons who responded to a standard questionnaire; none had IgM antibodies. Seropositivity was similar for males (25.4%) and females (21.1%), increased markedly with age for both sexes, and varied considerably among compounds (groups of huts) (0-37.5%). Risk factors for past RVF virus infection were nursing sick people, assisting animals during abortions/births, and treating sick animals. In all age groups, odds ratios (ORs) for RVF viral antibody among females who reported treating sick animals were three to six times greater than for those who did not. The ORs for males who reported assisting with animal births/abortions and nursing sick people were approximately five times those for males who did not. Serologic prevalence of RVF viral antibody among sheep averaged 30.1% overall (0.8% IgM), but varied among compounds (0-66.7%) in a manner different from that of humans. The seasonal abundance and relative density of potential mosquito vectors were estimated by monthly samples captured in Centers for Disease Control and Prevention-type traps. Mosquito abundance varied seasonally with rainfall (> 90% captures during four months). Species diversity was large (28 spp.), dominated by Aedes and Culex. Rift Valley fever virus was not isolated from 142 pools of 2,956 unengorged mosquitoes tested, although three other arboviruses were found. Results indicate that RVF is endemic in this region, people are at considerable risk of infection, and that a heretofore unrecognized mode of human infection under nonepizootic conditions may be transmission via contact with infected animals or humans.

Temperature- and humidity-dependent longevity of unfed adult Hyalomma truncatum (Acari: Ixodidae).

The survival of unfed adult Hyalomma truncatum Koch held under different regimes of constant temperature (5, 17, 24, and 30 degrees C) and relative humidity (10, 50, and 80%) was monitored during > 1 yr. Longevity of this medically important African tick was shortest at the highest temperature and lowest relative humidity (100% dead at week 25). Conversely, H. truncatum lived longest at lower temperatures and higher relative humidity (< 100% dead at week 64). The combined effects of temperature and humidity, measured as vapor pressure deficit, were strongly related to survival of these ticks. The survival of males and females was similar and was independent of the weight of ticks. These findings have implications for the maintenance and study of laboratory colonies of H. truncatum and for the development of tick control strategies to reduce vectorial capacity.

Risk factors for Crimean-Congo hemorrhagic fever in rural northern Senegal.

The extent of infection among 722 residents of an enzootic focus of Crimean-Congo hemorrhagic fever (CCHF) virus in rural northern Senegal and putative modes of transmission were studied by a cross-sectional seroprevalence survey done from February through May 1989. Anti-CCHF virus IgG was found in 13.1% of 283 persons who completed a standard questionnaire and provided blood samples. Seropositivity rates were similar between sexes and increased significantly with age among nomadic persons. Behavior patterns providing exposure to multifactorial risk factors were gender-based. Male risk factors, primarily associated with herding activities, included sleeping outside during seasonal migrations (also a risk factor for nomadic women), bite by a tick (adult male Hyalomma truncatum), tick bite during the cool dry season, and contact with sick animals. Human infection of CCHF occurred more frequently or with less mortality in the region studied than has been found elsewhere in Africa; however, the rate of seroconversion-associated illness is undetermined. Hyalomma ticks appear to be the primary transmission mode.