Differences on biological attributes of three populations of Meccus pallidipennis Stål (Hemiptera: Reduviidae).

BACKGROUND & OBJECTIVES: Meccus pallidipennis is one of the most epidemiologically important vectors of Trypanosoma cruzi to reservoir hosts in nine states of Mexico. Triatomines occurring in distinct locations normally adapt to local conditions. The aim of this study was to examine the biological attributes of three populations of M. pallidipennis from areas with different environmental characteristics as a factor influencing the triatomine capacity for T. cruzi transmission. METHODS: The values of biological parameters related to the life cycle, the number of blood meals to molt to next instar, fecundity and percentage of females after a biological cycle of three populations of M. pallidipennis were evaluated. A cohort of each of the three studied populations from different geographical areas of Mexico was maintained under similar laboratory conditions and then compared with each other. RESULTS: The life cycle was less than six months in all the studied cohorts, with differences among them. The number of blood meals to molt was lower for the cohort from Izϊcar de Matamoros. Laid eggs per day per female was lower for the cohort from Luvianos. In contrast, no important differences were recorded on the percentage of mortality, egg eclosion rate or percentages of obtained females. INTERPRETATION & CONCLUSION: It was found that an important level of heterogeneity exist between the three studied populations of M. pallidipennis, apparently influenced by the remarkable differences on environmental conditions on the localities where the founders were initially collected, that emphasizes the necessity of studies on local populations of triatomines.

Biological Parameters of Three Populations of Triatoma dimidiata s. s. (Hemiptera: Reduviidae) From Western Mexico.

Chagas disease is a very important vector-borne disease in México, and Triatoma dimidiata sensu stricto (Latreille) is one of the most important vectors of Trypanosoma cruzi Chagas, mainly in southern and central states. In the Pacific Coast states with the highest prevalence of human T. cruzi infection, T. dimidiata s. s. is considered as a secondary vector. However, the vectorial capacity of those populations has not been studied. Therefore, the vector characteristics of three populations of T. dimidiata s. s. in western México were evaluated in this study. The populations were maintained in the laboratory at 27 ± 1°C and 75% ± 5% RH with a 12:12 h (light:dark) regime, fed on rabbits in a fortnight basis. The development times were short (172-238 d), and the number of bloodmeals to molt was low (11). Mortality was moderate (36-45%), the onset of feeding was relatively rapid (0.5-1.7 min), and feedings were extended (>15 min). More than 40% of individuals in most instars defecated in one of three categories: <1 min when feeding (5-37.9%), immediately after feeding (9-28.6%), or in <1 min post feeding (7-25.8%). The median number of laid eggs was high (over 2.5) in the three populations, as were the egg eclosion rates (>86%). Thus, the T. dimidiata s. s. in the three populations are potentially efficient vectors of T. cruzi and could contribute to the high prevalence of infection in human populations in western México.

Chagas disease: Importance of rats as reservoir hosts of Trypanosoma cruzi (Chagas, 1909) in western Mexico.

In Mexico, the role of most species of mammals involved in the transmission cycle of Trypanosoma cruzi Chagas, 1909 is poorly known. It was carried out a study to investigate the importance of rats as reservoir of T. cruzi in western Mexico, an area with important risk of transmission of T. cruzi to human. Thirty-eight human dwellings were searched on two representative towns of western Mexico along twelve months for collection of rats and triatomines. Study rats (Rattus norvegicus) Berkenhout, 1769 and triatomines (Meccus phyllosomus longipennis) (Usinger, 1939) were collected inside and outside human dwellings. Most rats (68.6%, n=312) and triatomines (68.7%, n=217) were collected along months of the hot season. Most rats (59.3%) were collected in peridomiciliary areas. From 312 examined rats, 71 (22.7%) were positive for T. cruzi on examination by Indirect Hemagglutination, which was confirmed by xenodiagnosis. From the 217 examined triatomines, 169 (77.9%) were infected by T. cruzi. The presence of infected rats and triatomines was highly related since on every studied human dwelling where infected triatomines were collected, infected rats were also found. Rats seem to constitute an important domiciliary and peridomiciliary reservoir for T. cruzi, furthering the risk of infection for human beings.

[Use of a directory of specialized services and guidance in the healthcare system: the example of the Orphanet database for rare diseases]. / Utilisation d'un annuaire des services spécialisés et orientation dans le système de soins: l'exemple d'Orphanet dans les maladies rares.

BACKGROUND: Orphanet is a database of rare diseases which includes a directory of services providing information on professional experts working either in laboratories offering diagnostic tests or in specialized outpatient clinics. The printed directory is sent to these experts, to all relevant hospital departments (public and private), healthcare authorities, and patient support groups. The directory is also available online (www.orpha.net). The aims of this study were (i) to determine how the directory is used to refer patients and send specimens, and (ii) to investigate its impact on patient referral. METHODS: Data were obtained from experts and patient support groups concerned with rare diseases, as well from non-expert health professionals and patients. Emphasis was placed on knowledge of the Orphanet database, use of the directory as a tool for referrals, opinion of users about the quality of the directory, and opinion of the referenced experts about its possible impact on their referrals. Four methods of data collection were used: (i) a postal questionnaire to all referenced experts; (ii) an on-line questionnaire posted for a few hours on the Orphanet Website that had to be completed to access the site; (iii) interviews with 25 of the referenced experts; (iv) interviews with 35 leaders of patient organizations. Data were analysed using the chi2 test and logistic regression. RESULTS: Response rates were good: 74% of laboratory experts (224/304) and 68% of clinicians (459/678) answered the questionnaire. The responders proved to be representative. Among those who responded, 85% of the laboratory experts and 80% of clinician experts used Orphanet. More than two-thirds of them used Orphanet to identify (other) laboratories to them send specimens, and (other) clinicians for patient referral. Some non-expert hospital-based clinicians had nearly the same use. Patient support groups also used the directory. Persons using the directory happened to know Orphanet in their professional environment. Conversely, patients, non-MDs healthcare professionals and professionals in private practice discovered Orphanet using search engines, often when searching information about a rare disease. Of those who had already accessed the directory, most (94%) consider that the quality of the lists was "good" or" rather good". Among the experts, 29% of laboratories and 9% of clinicians considered that Orphanet had an impact on their referrals. CONCLUSION: The Orphanet directory is used to refer patients and specimens, especially by experts and patient organizations. It appears to have more impact on referrals within the healthcare system for laboratories than for specialized outpatient clinics. The impact is strong when expertise in the field is very scarce.

Geographic variation on biological parameters of Meccus picturatus (Usinger), 1939 (Hemiptera: Reduviidae).

The biological parameters related to the life cycles of three populations of Meccus picturatus (Usinger) (Hemiptera: Reduviidae), one of the main vectors of Trypanosoma cruzi Chagas (Trypanosomatida: Trypanosomatidae), were evaluated. A cohort of each of three populations from geographically isolated localities in western Mexico was maintained under similar laboratory conditions, after which all three populations were compared to each other. In each cohort, 50.9 to 72.1% of nymphs completed the cycle. The average time from N1 to adult was approximately 175 days and different for the three studied cohorts. The number of blood meals between molts varied from one to three. The hatching rates as well as the fecundity per female per day were different among the three studied populations. Our results show that the three isolated populations are statistically different in some parameters from each other, which points to the importance of studying the biological characteristics of local populations of triatomines for estimating their capacity of transmitting T. cruzi to reservoir hosts.

Combining two teaching techniques for young children on Aedes aegypti control: effects on entomological indices in western Mexico.

A study of the effect of educating four- to six-year-old children in mosquito control was recently conducted in a city in the state of Jalisco, western Mexico. Four neighborhood districts were selected. Children attending one kindergarten in each of two experimental districts were taught mosquito control with a video from the American Mosquito Control Association (AMCA), joined to the use of the AMCA Touch Table Technique. The entomological indices monitored in the study decreased significantly (P<0.05) in houses in the experimental districts, apparently because parents acted on the comments and suggestions of the children and eliminated or monitored containers used as oviposition sites by mosquitoes. Based on these results, combining both techniques for teaching children mosquito control is a potentially useful tool for control efforts in Mexico and other places in Latin America.