Ana E. Jimenez

Temporal and spatial variation of phlebotomine (Diptera: Psychodidae) community diversity in a cutaneous leishmaniasis endemic area of Costa Rica.

Abstract Phlebotomine sand fly species composition and diversity were studied in Acosta, an area of Costa Rica endemic for cutaneous leishmaniasis. Two CDC miniature light traps per house were set overnight in 72 houses distributed in 6 localities, once a month, during the rainy seasons of 1994 and 1995. Of the 22 species collected, the most common were Lutzomyia serrana (Damasceno & Arouck), L. youngi Feliciangelli & Murillo, L. ylephiletor (Fairchild & Hertig), L. shannoni (Dyar), L. cruciata (Coquillett), L. gomezi (Nitzulescu), L. sanguinaria (Fairchild & Hertig), and Warileya rotundipennis (Fairchild & Hertig). The Czekanowsky index and the Sorensen index as modified by Bray and Curtis to consider abundance were used to compare species composition and β-diversity. Comparisons were made among localities within years, between years, and localities each year. The data strongly indicated that phlebotomine species composition is more stable than diversity or abundance.

Serological survey of small mammals in a vesicular stomatitis virus enzootic area.

Small mammals were captured in a Costa Rican dairy farm located in a vesicular stomatitis virus (VSV) enzootic focus, in order to determine which species were naturally infected by this virus. Monthly captures were performed from March 1989 to February 1990. Eighty-four individuals belonging to the orders Rodentia (n = 52), Insectivora (n = 31) and Marsupialia (n = 1) were captured. Only Sigmodon hispidus had neutralizing antibodies to VSV; among 21 animals, six had antibodies to Indiana, one to New Jersey, and two to both serotypes. In addition, groups of 40 sentinel mice (Mus musculus, strain C3H) were placed in cages distributed throughout the farm. Each group was exposed for 1 mo over a period of 1 yr. None of 312 sentinel mice developed antibodies against either VSV serotype. Based on these results, we believe that S. hispidus might be part of the natural cycle of VSV in this enzootic focus. Caged Mus musculus do not seem appropriate for monitoring VSV activity in this area.

Survey of Small Rodents and Hematophagous Flies in Three Sentinel Farms in a Costa Rican Vesicular Stomatitis Endemic Region

Abstract: A survey of rodents and hematophagous flies was conducted on three farms located in an area endemic for vesicular stomatitis to determine the species composition of each zoological group occurring in these areas. Eleven species of small rodents were collected and identified. Individuals from forty‐nine species of hematophagous flies of the families Ceratopogonidæ, Culicidæ, and Phlebotominæ were captured and identified. The species compositions in each group were compared between farms. Rodents were tested for antibodies to vesicular stomatitis, New Jersey and Indiana serotypes. Seven species had antibody titers greater than 1:10. Attempts to isolate the virus produced negative results for all the species tested.

Longitudinal studies in the epidemiology of vesicular stomatitis on Costa Rican dairy farms.

Abstract: Twenty‐three Costa Rican dairy herds from an vesicular stomatitis (VS) endemic area were under an active surveillance between April 1997 and March 1999. Ninety‐two confirmed cases of VS New Jersey were found. Factors associated with clinical cases of VS virus New Jersey were: Parity (animals of parity 4 or 5 were 5.3 times more likely to present a clinical case than animals of parity 3 and lower; on the other hand, animals of parity 6 and higher showed an odds 4.6 times greater than animals of parity 3 and lower.) Ecological life zone (animals in premountain moist forest were 7.4 times more likely to present clinical cases than animals in lower mountain rain forest). Factors associated with seropositivity at the time of birth were farm and breed (Jersey calves had an odds 14.7 times greater than Holstein calves). Seroconversion, defined as the first twofold increase in the titers of the blood, was associated with farm and showed four peaks during the study period, September (wet season) 1997, February (dry season) 1998, September 1998, and February 1999. Finally, time to event analysis showed difference between farms and age, older animals showed the first seroconversion earlier than younger animals.