study on culex species and culex transmitted diseases in Al-Madinah Al-Munawarah, Saudi Arabia

Culex mosquitoes transmit bancroftian filariasis and arboviruses as West Nile Virus in the Middle East including Saudi Arabia. However, the prevalent Culex species in Al-Madinah region have not been reported and their role in disease transmission remains to be clarified. This work aimed to investigate the role of Culex in transmission of Wuchereria bancrofti, West Nile virus, Saint Louis encephalitis and Eastern Equine encephalitis in Al-Madinah, Saudi Arabia. Also, it was done to document the prevalent Culex species and to shed light on their bionomics and habits. Culex mosquitoes were collected using spray sheets and CDC light traps with CO2 release from July 2007 till June 2008. Also, Culex larvae were collected for 8 months during that period. Culex seasonal distribution and bionomics were documented and taxonomical identification was done. Females were dissected and microscopically examined for filarial stages. In addition, they were screened by the Vec-Test for West Nile virus, Saint Louis encephalitis and Eastern Equine encephalitis. A total of 3.6% human rooms and 4.7% of animal sheds were positive for Culex; more in the period of January-June 2008, compared to July-December 2007. Seven Culex species were found, two of which were recorded for the first time in the region; C. duttoni and C. decens. C. pipiens and C. quinquefasciatus were the most abundant; 59.3% of collected adults were C. pipiens, while C. quinquefasciatus constituted 22.1%. As for collected larvae, C. pipiens constituted 60% of them, whereas C. quinquefasciatus totalled 20%. Only C. pipie/Is was found to harbor West Nile Virus. In contrast, no other viruses or W bancrfoti stages were detected in the examined mosquitoes. There is a potential danger of the transmission of West Nile Virus in Al-Madinah especially by C. pipiens. Also, the possibility of future transmission of W. bancrofti, and the establishment of new endemic foci of bancroftian filariasis in the region, couldn't be overruled

Estefanofilariose em humanos: ocorrência e mecanismos de transmissão / Stephanofilariasis in humans: occurrence and transmission mechanisms

Descreve-se aqui o encontro do helminto Stephanofilaria spp., em dermatite nodular ulcerativa em seres humanos, sendo as ulceras pesquisadas de dimensões variadas e com alguns anos de existência. Acredita-se que, a presença desse parasita, que afeta diversas espécies de animais domésticos e silvestres, possa agravar o quadro com as lesões produzidas nos vasos venosos e linfáticos, reduzindo a circulação, retardando a cicatrização. O ciclo deste parasita no ser humano, também é descrito.

This work describes the occurrence of the helminth Stephanofilaria spp in ulcerative nodular dermatitis in humans. The ulcers observed presented a variety of sizes and some years of existence. It is believed that the presence of this parasite, which affects several domestic and wild animal species, may harm human health through lesions produced in venous and lymphatic vessels that reduce blood circulation and retard the healing process. The cycle of this parasite in humans is also described.

Illustrated keys to the mosquitoes of Thailand. IV. Anopheles.

Illustrated keys for the identification of the larvae and adult female Anopheles mosquitoes of Thailand are presented along with distribution maps, tabulated bionomics information, and a checklist. A total of 73 species are treated, including 71 previously and newly described species (An. cracens = dirus B, An. scanloni = dirus C, An. baimaii = dirus D, An. latens = leucosphyrus A, and An. epiroticus = sundaicus A). Also, two undescribed species are included, i.e., An. minimus C and a new species near An. gigas. Thirty-four chromosomal forms of 14 species are discussed, with suggestions provided for resolving their taxonomic status.

Bionomics studies of Mansonia mosquitoes inhabiting the peat swamp forest.

The present study was conducted in the years 2000-2002 to determine the bionomics of Mansonia mosquitoes, vectors of nocturnally subperiodic Brugia malayi, inhabiting the peat swamp forest, "Phru Toh Daeng", Narathiwat Province, Thailand. Fifty-four species of mosquitoes belonging to 12 genera were added, for the first time, to the list of animal fauna in the peat swamp forest. Mansonia mosquitoes were the most abundant (60-70%) by all collection methods and occurred throughout the year with a high biting density (10.5-57.8 bites per person-hour). Ma. bonneae was most prevalent (47.5%) and fed on a variety of animal hosts, including domestic cats, cows, monkeys, and man with a maximum biting density of 24.3 bites per person-hour in October. The infective bites were found for the first time in Ma. annulata collected at Ban Toh Daeng (13 00-14 00 hours) and also Ma. bonneae at forest shade (16 00-17 00 hours) and in a village (20 00-21 00 hours) with rates of 0.6, 1.1 and 1.0%, respectively. The biting activities of these two species occurred in both the day and night time, with two lower peaks at 10 00 hours (18.5 bites per person-hour) and 13 00-15 00 (8.5-10.0 bites per person-hour) hours, but the highest peak was 19 00-21 00 hours (31.5-33.0 bites per person-hour) The biting activity patterns corresponded with the periodicity found in man and domestic cats and may play an important role in either transmission or maintenance of the filarial parasites in the peat swamp forest. The relative role of Ma. bonneae and Ma. uniformis in different environmental settings (primary swamp forest and open swamp) on the transmission of nocturnally subperiodic B. malayi merits further study.

Evaluation of mosquitocidal activity of Annona squamosa leaves against filarial vector mosquito, Culex quinquefasciatus Say.

Methanolic extract of leaves of A. squamosa was tested for mosquitocidal effect against C. quinquefasciatus. A liquid mosquito insecticide formulation was prepared with the extract (1, 3 and 5 %w/w) using deodorized kerosene as solvent and investigated for its knock-down and 24 hr mortality. The extract formulation produced dose dependent activity, exhibited significantly shorter knock down KD50 and KD90 values and produced significant mortality. The results suggest the potential mosquitocidal effect of A. squamosa on C. quinquefasciatus.

Transfusion transmitted diseases.

Transfusion transmitted disease (TTD) is a major challenge to the transfusion services all over the world. The problem of TTD is directly proportionate to the prevalence of the infection in the blood donor community. In India, hepatitis B/C, HIV, malaria, syphilis, cytomegalo virus, parvo-virus B-19 and bacterial infections are important causes of concern. Hepatitis B and C infections are prevalent in India and carrier rate is about 1-5% and 1%, respectively. Post transfusion hepatitis B/C is a major problem in India (about 10%) because of low viraemia and mutant strain undetectable by routine ELISA. HIV prevalence among blood donors is different in various parts of the country. It may not be so alarming as projected by some agencies. In one study from north India, confirmed HIV positivity was found in 0.2/1000 blood donor. Post transfusion CMV is difficult to prevent but use of leukocyte filters may help to reduce it significantly. Parvo virus B-19 infection in blood donors is 39.9% which may increase morbidity in multitransfused or immunocompromised patients. Current symphilis tests may not be sensitive but it should be continued to exclude high-risk donors. Malaria is a real problem for India due to the lack of a simple and sensitive screening test. Incidence of bacterial contamination is greatly reduced due to improved collection/preservation techniques and use of antibiotics in patients. However, proper vigilance and quality control is needed to prevent this problem. Total dependence of altruistic repeat voluntary donors and use of sensitive laboratory tests may help Indian blood transfusion services to reduce incidences of TTDs.

Aedes albolateralis, a potential vector of nocturnally subperiodic Wuchereria bancrofti and dengue type 2 virus.

The susceptibility of Aedes albolateralis to nocturnally subperiodic Wuchereria bancrofti and dengue type 2 virus was investigated by using artificial membrane feeding and intrathoracic inoculation techniques, respectively. The results indicated that Ae. albolateralis was susceptible to nocturnally subperiodic W. bancrofti (susceptibility rate = 9.43%) and dengue type 2 virus (susceptibility rate = 100%), suggesting the potential vector of the two pathogens.

Effects of a juvenoid, DPE-28, on biology and behaviour of Culex quinquefasciatus, the human filariasis vector.

Studies on the effect of a juvenoid, DPE-28 (2,4-dinitrophenyl-2',6'-di-tertiarybutyl phenyl ether) on biology and behaviour of Cx. quinquefasciatus showed that the developmental duration, sex ratio, mating success and blood feeding were considerably affected by the exposure of larvae and pupae to the compound. Exposure of fourth instar larvae to 0.007 (EI90) and 0.0019 (EI50) ppm of DPE-28 prolonged the duration of pupation by 58.6 and 52.4 hr and delayed the adult emergence by 35.4 and 17.7 hr in males and 36.8 and 21.1 hr in females respectively. Exposure of freshly ecdysed pupae to 10 and 5 ppm delayed the adult emergence with respect to the control by 54.3 and 32.4 hr in males and 55.2 and 33.2 hr in females respectively. The sex ratio of the adults emerged from treated larvae and pupae was also affected. The female mosquitoes that survived from the exposed fourth instar larvae and pupae exhibited a low blood engorgement ratio. This depression in blood feeding was more pronounced in adults emerged from treated pupae than that of treated fourth instar larvae. A significant proportion of adults emerged from treated larvae and pupae were able to feed only partially. Mating success of the treated populations declined considerably when crosses were made between the males and females emerged from treated fourth instar larvae and pupae. The adults emerged from treated larvae and pupae showed a significant reduction in the oviposition.

Experimental infection of Culex (Culex) quinquefasciatus and Aedes (Stegomyia) aegypti with Wuchereria bancrofti

A study was conducted to determine the susceptibility of local strains of Culex quinquefasciatus and Aedes aegypti to infection with the strain of Wuchereria bancrofti that occurs in Maceió, State of Alagoas, Brazil. Cx. quinquefasciatus blood fed simultaneously on the same microfilariae carrier ingested more blood and 2-3x more microfilariae than Ae. aegypti. Survival rates of both species of insects living for 21 days after blood feeding on microfilaraemic patients were not significantly different from the survival rates of mosquitoes that blood fed on amicrofilaraemic individuals. W. bancrofti parasites underwent normal development in Cx. quinquefasciatus, with third stage larvae first being recorded on the 11th day post infection, and their numbers increasing thereafter. Development of filariae in Ae. aegypti did not proceed beyond the first larval stage, and there was a progressively increasing number of non-viable larvae with the passage of time. It is concluded that Ae. aegypti is not involved in the transmission of W. bancrofti in Maceió.

Filariose bancroftiana no Brasil / Bancroftian filariasis in Brazil

Foi feita revisäo dos estudos sobre a distribuiçäo geográfica e prevalência da filariose linfática bancroftiana no Brasil. Entre 1951 a 1958 foram realizados inquéritos hemoscópicos e entomológicos no país, sendo a transmissäo autóctone comprovada em apenas 11 Municípios: Ponta Grossa (SC), 14,5 por cento; Belém (PA), 9,8 por cento; Barra de Laguna (SC), 9,4 por cento; Recife (PE), 6,9 por cento; Castro Alves (BA), 5,9 por cento; Florianópolis (SC), 1,4 por cento; Säo Luís (MA), 0,6 por cento; Salvador (BA), 0,4 por cento; Maceió (AL), 0,3 por cento; Manaus (AM), 0,2 por cento e Porto Alegre (RS), 0,1 por cento. A distribuiçaö da parasitose era urbana e focal, principamente em cidades litorânes. As açöes de controle implementadas levaram a uma precíavel queda nas taxas de microfilarêmicos sendo consideradas, a partir de entäo, áreas endemicas para Filariose linfática no Brasil somente as cidades de Belém e Recife. Estudos recentes mostram a transmissäo ativa de parasitose, com prevalências superiores às detectadas no passado, em Maceió, cujo foco era considerado extinto, e em Recife. O conhecimento da situaçäo atual de bancroftose no Brasil é de fundamental importância para a implementaçäo de açöes de controle da endemia envolvendo o Ministério da Saúde e órgäo de saúde pública.

Prediction of villages at risk for filariasis transmission in the nile delta using remote sensing and geographic information system technologies

Remote sensing and geographic information system [GIS] technologies were used to discriminate between 130 villages in the Nile Delta, at high and low risk for filariasis, as defined by microfilarial prevalence. Landsat Thematic Mapper [TM] data were digitally processed to generate a map of land-cover as well as spectral indices such as NDVI and moisture index. A Tasseled Cap transformation was also carried out on the TM data which produced 3 more indices [brightness, greenness and wetness]. GIS functions were used to extract information on land-cover and spectral indices within 1 km buffers around the study villages. The relationship between satellite data and prevalence was investigated using discriminant analysis. The analysis indicated that the most important landscape elements associated with prevalence were water and marginal vegetation, while wetness and moisture index were the most important indices. Discriminant functions generated for these variables were able to predict correctly 80% and 74% of high and low prevalence villages, respectively, with an overall accuracy of 77%. The present approach provided a promising tool for regional filariasis surveillance and helps direct control efforts

Filariasis transmission potential of mosquitoes to humans of different age groups

Age-specific levels of Wuchereria bancrofti infection determined by microfilaremia in filarious 10 to 60 years old males from an endemic village revealed that microfilaria intensity was higher in younger age, presumably because of increased vector biting rate of younger individuals. Out of 1334 Cx. pipiens captured while attempting to bite 51 child-adult bait pairs, 54% selected a host in the 10 - 15 age group. Biting preference towards children was more elevated [79.2%] later than earlier in the night. Frequency distribution of age- specific biting collections indicated that 62.7% recorded exceeding numbers of bites on children, 21.6% adult biting, and 15.7% equal biting of one of the baits in the pair. Furthermore, 21.6% of the children were exposed to nightly bites ranging from 21 to 64 and only 7.8% of the adults experienced from 21 to 85 bites. Mosquito biting intensity averaged 14.2 and 11.6 bites/night for children and adults, respectively. Children experienced 22.4% more bites per night than adults. Thus, children are more exposed to filaria infection and seem to represent an important source of infection. It is concluded that attempts at widespread control of filariasis in the densely populated Nile Delta, where youngsters may account for an immense proportion of the local population should concentrate on immatures

Host-parasite relationships of wuchereria bancrofti and mosquito hosts, culex pipiens L and aedes caspius pallas

The reciprocal deleterious effects of both the mosquito host and its parasite were reported. Anatomical and histological examinations of mosquitos revealed minor differences in the general structure of the foregut of either species. However, the cibarial pump of Ae. caspius lacked a cibarial armature and damage inflicted to some of the microfilariae [mf] ingested by this mosquito was not mechanical. In contrast, the cibarial armature of Cx. pipiens consisted of 24 delicate teeth, which did not seem to affect ingested mf. The peritrophic membrane [pm] did not constitute a significant barrier to mf, migrating through the midgut wall of either mosquito. Traversing mf perforated the pm and displaced the basement membrane. Within the thorax of Cx. pipiens, the parasite completed its development synchronously. In contrast, mf ingested by Ae. caspius did not develop beyond the sausage stage and many of these larvae were vacuolated. In both mosquitos, parasitized thoracic muscle fibers were tunneled and only in Ae. caspius, their nuclei were pyknotic. No worm encapsulation or melanization was observed in either mosquito

Parasitosis y transfusión sanguínea / Parasitosis and blood transfusion

La transfusión de sangre y sus componentes, indicada de manera sensata y precisa, es de enorme ayuda terapéutica, pero también conlleva riesgos, por lo cual debe realizarse un control estricto en la selección de donadores, en la recolección, conservación y transporte de la sangre. Las infecciones son uno de los riesgos de la transfusión sanguínea; en el presente trabajo nos referimos específicamente a los parásitos que pueden ser transmitidos por esta vía y la manera de evitarlo

Bancroftian filariasis in two urban areas Recife, Brazil: the role of individual risk factors

A Filariose bancroftiana esta se disseminado em areas humanas de regioes endemicas como no Recife, nordeste do Brasil, onde se constitui em um problema de microfilaremia e doenca filareal em duas areas urbanas do Recife, estudando sua associacao com caracteristicas individuais e variaveis realacionadas ao contacto com valores. O inquerito parasitologico foi realizado atraves de um censo "porta-a-porta" e a pesquisa de microfilarias foi efetuada pela tecnica da gota espessa utilizando 45µ de sangue capilar entre 20:00 e 24:00 horas...