Susceptibility of mosquito vectors to Dirofilaria immitis on Madeira Island, Portugal

Dirofilaria immitis (Leidy, 1856), an agent of heartworm disease, is an important parasite from both the veterinary standpoint and as a model to study human filariasis. It is a mosquito-borne filarial nematode which inhabits the right ventricle and pulmonary arteries of dogs. D. immitis is an important disease agent on Madeira Island with about 30% of dogs testing positive for this worm. Nevertheless, the vectors of this parasite in Madeira have never been studied, nor has the interaction between pathogen and vector, or the environmental variables that might influence heartworm transmission. Innate susceptibility to infection is only one component of vector competence, and field isolation of naturally infected mosquitoes has shown the capability of D. immitis to exploit a great diversity of vector species under natural conditions. The purpose of this work was to determine which mosquitoes are vectors of heartworm disease, the relation between population density and environment, and the association between immune response of the vector to the filarial parasite. Seasonal abundance of Culex theileri and Culex pipiens molestus was studied. Correlation and canonical correspondence analysis were performed using abundance data of these two species with selected weather variables, including mean temperature, relative humidity and accumulated precipitation. The most important factor determining Cx. theileri abundance was accumulated precipitation, while Cx. pipiens molestus abundance did not have any relationship with weather variables. Field studies were performed to verify whether Cx. theileri Theobald functions as a natural vector of D. immitis on Madeira Island, Portugal. Cx. theileri tested positive for D. immitis for the first time. The same study was made regarding Cx. p. molestus. Two abnormal L2 stage filarial worms were found in Malpighian tubules in field caught Cx. p. molestus. In the laboratory, two strains of Cx. p. molestus were studied for their susceptibility to D. immitis. None presented infective-stage larvae. Finally, because Cx. p. molestus is an autogenous mosquito, we evaluated the reproductive costs when this mosquito mounts an immune response against D. immitis in the absence of a blood meal. This mosquito showed an active immune response when inoculated intrathoracically with microfilariae (mf) of the heartworm. The ovaries from mosquitoes undergoing melanotic encapsulation developed more eggs than those which could not melanize the mf. This fact is contradictory with some previous studies of reproductive costs in Armigeres subalbatus and Ochlerotatus trivittatus, and it was the first time that an autogenous mosquito was used to study this subject.

Asthma Polymorphic Loci genotyping in Madeira population: identification of potential genetic markers of disease susceptibility, severity and clinical relevance

Asthma is a complex disease, influenced by both environmental and genetic factors. In this study, the analysis of multiple environmental factos assessed by questionnaire and the genotyping of SNPs IL131c.144 G/A, IL41590 C/T, IL41RP2 253183, ADRB21c.16 A/G, ADAM331V4 C/G, ADAM331S1 c.710 G/A, GSDML1236 C/T and STAT6121 C/T were performed in a sample of Madeiran asthmatic patients and their families, and their association to asthma susceptibility and severity was assessed. Family, environmental, social and individual factos such as the presence of rhinitis in one of the parents,the habitation conditions, the family smoking habits, individual food habits and allergen sensitivity, were found to account for asthma severity. IL41590*T and IL41RP2*183$ alleles as well as the combined genotypes IL41590*CT/IL41590*TT and IL41 RP2*253183/IL41RP2*253183 were associated to both asthma susceptibility and severity.GSDML1236*TT was found associated only to asthma severity.Allele ADAM331 V4*C was significantly overM transmitted to asthmatic offspring being linked with the disease by TDT. These findings suggest that in addition to environmental influences, IL41 590 C/T, IL41RP2 253183, ADAM331V4 C/G and GSDML1236 C/T SNPs may constitute important genetic factos contributing to asthmasusceptibility and/or severity in Madeira population.