Your search found 5 records
1 Amerasinghe, P. H.; Amerasinghe, F. P.; Konradsen, F.; Fonseka, K. T.; Wirtz, R. A.. 1999. Malaria vectors in a traditional dry zone village in Sri Lanka. American Journal of Tropical Medicine and Hygiene, 60(3):421-429.
Malaria ; Disease vectors ; Waterborne diseases ; Public health / Sri Lanka / Mahameegaswewa / Huruluwewa
(Location: IWMI-HQ Call no: IWMI 616.9362 G744 AME Record No: H024197)
Malaria transmission by anopheline mosquitoes was studied in a traditional tank-irrigation-based rice-producing village in the malaria-endemic low country dry zone of northcentral Sri Lanka during the period August 1994-February 1997. Adult mosquitoes were collected from human and bovid bait catches, bovid-baited trap huts, indoor catches, and pit traps. Mosquito head-thoraces were tested for the presence of Plasmodium falciparum and P. vivax, and blood-engorged abdomens for the presence of human blood by ELISAs. House surveys were done at two-day intervals to record cases of blood film-confirmed malaria among the villagers. A total of 7,823 female anophelines representing 14 species were collected. Trends in anopheline abundance were significantly correlated with rainfall of the preceding month in An. annularis, An. barbirostris, An. subpictus, An. vagus, and An. varuna, but were not significant in An. culicifacies and An. peditaeniatus. Malaria parasite infections were seen in seven mosquito species, with 75% of the positive mosquitoes containing P. falciparum and 25% P. vivax. Polymorph PV247 was recorded from a vector (i.e., An. varuna) for the first time in Sri Lanka. Computations of mean number of infective vector (MIV) rates using abundance, circumsporozoite (CS) protein rate, and human blood index (HBI) showed the highest rate in An. culicifacies. A malaria outbreak occurred from October 1994 to January 1995 in which 45.5% of village residents experienced at least a single disease episode. Thereafter, malaria incidence remained low. Anopheles culicifacies abundance lagged by one month correlated positively with monthly malaria incidence during the outbreak period, and although this species ranked fifth in terms of abundance, infection was associated with a high MIV rate due to a high CS protein rate and HBI. Abundance trends in other species did not correlate significantly with malaria. It was concluded that An. culicifacies was epidemiologically the most important vector in the study area.
2 Rodriguez, M. H.; Gonzalez-Ceron, L.; Hernandez, J. E.; Nettel, J. A.; Villarreal, C.; Kain, K. C.; Wirtz, R. A.. 2000. Different prevalences of Plasmodium vivax phenotypes VK210 and VK247 associated with the distribution of Anopheles albimanus and Anopheles pseudopunctipennis in Mexico. The American Journal of Tropical Medicine and Hygiene, 62(1):122-127.
Malaria ; Waterborne diseases ; Disease vectors ; Anopheles albimanus ; Anopheles pseudopunctipennis ; Public health ; Statistical analysis ; Computer software / Mexico
(Location: IWMI-HQ Call no: PER Record No: H026553)
3 Wirtz, R. A.; Burkot, T. R.; Graves, P. M.; Andre, R. G. 1987. Field evaluation of enzyme-linked immunosorbent assays for Plasmodium falciparum and Plasmodium vivax Sporozoites in mosquitoes (Diptera: Culicidae) from Papua New Guinea. Journal of Medical Entomology, 24(4):433-437.
(Location: IWMI-HQ Call no: P 6647 Record No: H033568)
4 Amerasinghe, P. H.; Amerasinghe, F. P.; Wirtz, R. A.; Indrajith, N. G.; Somapala, W.; Pereira, L. R.; Rathnayake, A. M. S. 1992. Malaria transmission by Anopheles subpictus (Diptera: culicidae) in a new irrigation project in Sri Lanka. Journal of Medical Entomology, 29:577-581.
Irrigation programs ; Development projects ; Waterborne diseases ; Malaria ; Disease vectors ; Anopheles subpictus / Sri Lanka / Mahaweli Project
(Location: IWMI-HQ Call no: P 6673 Record No: H033682)
5 Amerasinghe, Priyanie H.; Alifrangis, M.; van der Hoek, Wim; Wirtz, R. A.; Amerasinghe, Felix P.; Konradsen, Flemming. 2005. Optimizing malarial epidemiological studies in areas of low transmission. Southeast Asian Journal of Tropical Medicine and Public Health, 36(5):1079-1084.
Malaria ; Epidemics ; Waterborne diseases ; Analysis ; Surveys ; Villages / Sri Lanka / Mahameegaswewa
(Location: IWMI HQ Call no: IWMI 614.532 G744 AME Record No: H041472)
Malaria risk factor studies have traditionally used microscopy readings of blood slides as the measure of malaria infection in humans, although alternatives are available. There is the need for an assessment of how the use of these alternative diagnostic approaches will influence the efficiency and significance of epidemiological studies. In an area of Sri Lanka with known risk factors for malaria, two cross-sectional surveys were done at the start and at the peak of transmission season. Microscopy was compared with enzyme-linked immunosorbent assays (ELISA) and polymerase chain reaction (PCR). The major risk factor in this area was the location of houses relative to confirmed vector breeding sites. At the peak of the transmission season, the results pointed in the same direction, irrespective of the diagnostic method used. However, the importance of distance from the breeding site was not statistically significant when microscopy was used, which can be explained by the lower prevalence of microscopy positivity in comparison to the prevalence of ELISAand PCR-positivity. This study suggests that in low-transmission areas, such as Sri Lanka, smaller sample sizes can be used for epidemiological research studies using PCR instead of microscopy to estimate parasite prevalence. This efficiency gain has to be weighed against the higher cost and complexity of the PCR. PCR cannot replace microscopy as the standard diagnostic procedure at the field level. ELISA is not directly comparable with microscopy and PCR but it can also be a useful tool in malaria epidemiological studies. This study indicates that cross-sectional surveys are only efficient if they take place during peak transmission season. Cross sectional surveys currently implemented by the Sri Lankan government in response to local malaria outbreaks can form the basis for valid epidemiological studies and be used for the generation of malaria risk maps if samples were also analyzed using PCR.
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