The mosquito Anopheles balabacensis balabacensis has been identified as a natural vector of at least two species of simian malaria in the monsoon forests of the northern Malay States. This mosquito is also a serious vector of human malaria from Viet Nam to northern Malaya. This is the first report of a mosquito which transmits both human and simian malaria in nature.
Dialysis disequilibrium syndrome (DDS) is a neurological disorder with varying severity that is postulated to be associated with cerebral oedema. We described a case of DDS resulting in irreversible brain injury and death following acute haemodialysis. A 13-year-old male with no past medical history and weighing 30kg, presented to hospital with severe urosepsis complicated by acute kidney injury (Creatinine 1422mmol/L; Urea 74.2mmol/L, Potassium 6.3mmol/L, Sodium 137mmol/L) and severe metabolic acidosis (pH 6.99, HC03 1.7mmol/L). Chest radiograph was normal. Elective intubation was done for respiratory distress. Acute haemodialysis performed due to refractory metabolic acidosis. Following haemodialysis, he became hypotensive which required inotropes. His Riker's score was low with absence of brainstem reflexes after withholding sedation. CT Brain showed generalised cerebral oedema consistent with global hypoxic changes involving the brainstem. The symptoms of DDS are caused by water movement into the brain causing cerebral oedema. Two theories have been proposed: reverse osmotic shift induced by urea removal and a fall in cerebral intracellular pH. Prevention is the key to the management of DDS. It is important to identify high risk patients and haemodialysis with reduced dialysis efficacy and gradual urea reduction is recommended. Patients who are vulnerable to DDS should be monitored closely. Low efficiency haemodialysis is recommended. Acute peritoneal dialysis might be an alternative option, but further studies are needed.
Comparative studies of vector efficiency were done with the Liverpool and Malaysian strains of Aedes (Finlaya) togoi for subperiodic Brugia malayi and Brugia pahangi. The Malaysian strain of A. togoi was found to take in fewer microfilariae under the same experimental conditions than the Liverpool strain. Also, for various microfilarial densities in the host's peripheral blood, the Malaysian strain had less mean infective larvae per fed mosquito than the Liverpool strain. The microfilarial intake of A. togoi was not affected by the site of feeding on the host affected by the site of feeding on the host. Most of the mosquitoes took in fewer microfilariae than expected. It is concluded from these studies that the Malaysian strain of A. togoi is a susceptible and reasonably good vector for subperiodic B. malayi and B. pahangi. Further field studies should be carried out to determine its importance as a natural vector of Brugian filariasis.
1. Three natural populations and a laboratory strain of Aedes albopictus were analysed for glucose phosphate isomerase by means of horizontal starch-gel electrophoresis. 2. The electrophoretic phenotypes were governed by five codominant Gpi alleles. 3. The commonest allele in all the four population samples was GpiC which encoded an electrophoretic band with intermediate mobility. 4. The distributions of GPI phenotypes were in accordance with Hardy-Weinberg expectations. 5. The four population samples could be differentiated by the presence of a unique Gpi allele or the absence of a particular Gpi allele.
An experiment was carried out with Mansonia mosquitos in an area endemic for subperiodic Brugia malayi to assess the applicability of the mark-release-recapture method to these mosquitos. An estimated 17,880 individuals of six species of Mansonia were marked with fluorescent dust and released: 453 Ma. annulata, 305 Ma. annulifera, 6,200 Ma. bonneae, 516 Ma. dives, 3,998 Ma. indiana and 6,408 Ma. uniformis. Twenty-three marked individuals were recaptured. Most recaptures were made one or two nights after their release, but one Ma. annulifera was recaptured five nights later and one Ma. bonneae had been marked and released 6-11 nights previously. The recaptured mosquitos were collected between 0.5 and 2.4 km from their release points.
Methods are described for the laboratory colonization of Coquillettidia crassipes. The highest rate of insemination occurred in 60 x 60 x 120 cm cages and better insemination in laboratory adapted F15 generation. Embryonation and hatchability of eggs ranged from 69.6 to 97.9% and 63.3 to 94.3% respectively. Gravid females laid egg rafts on water in 500 ml breakers with small leaves of Salvinia for resting. Newly hatched larvae were set up in a basal medium of guinea pig dung and water or liver powder, yeast powder and water. Larvae attached to aquatic plants or 'Keaykolour' ruffia snow white paper. The cultures with paper gave better yields. At present 21 generations of Cq. crassipes have been reared in the laboratory.
1. A total of 8 samples from three natural populations and a laboratory strain of Aedes albopictus were analysed for glycerol-3-phosphate dehydrogenase phenotypes by means of horizontal starch-gel electrophoresis. 2. The electrophoretic phenotypes were governed by three codominant Gpd alleles. 3. There was low variability, with the heterozygosity in the variable samples ranging from 0.02 to 0.12. 4. The commonest allele in all the population samples was GpdB which encoded an electrophoretic band with intermediate mobility. 5. There was no temporal or spatial variation.
A total of 37 species of mosquitoes from seven genera were collected in six villages in the Bengkoka Peninsula, Sabah State, during two visits in 1981 in connection with studies on malaria and filariasis. Fifty-five per cent of the total mosquitoes collected were Mansonia. An. collessi constituted a new record of the species from Sabah. An. balabacensis was found to be naturally infected with sporozoites. Ma. bonneae was found to be naturally infected with Brugia, probably B. malayi. Parous rates of An. balabacensis and Ma. bonneae were very high with consequent high probability of survival ideally suiting transmission of malaria and filariasis.
A strain of Clostridium bifermentans individualized as serovar malaysia (C.b.m.) according to its specific H antigen is toxic to mosquito and blackfly larvae when given orally. The toxicity occurs in sporulated cells which contain, in addition to spores, proteinic parasporal inclusion bodies and feather-like appendages; the amino acid content of the inclusion bodies is similar to that of Bacillus thuringiensis serovar israelensis (B.t.i.) and B. sphaericus crystals. The toxicity to Anopheles stephensi is as high as that of B.t.i. and the best strains of B. sphaericus. Culex pipiens is somewhat less susceptible, and Aedes aegypti much less. Pure parasporal inclusion bodies, isolated by ultracentrifugation on sucrose gradients, are highly toxic to mosquito larvae. The larvicidal power is destroyed by heating at 80 degrees C or by treatment with 50 mM NaOH. It is preserved by freeze-drying. The innocuity to mice of the sporulated cells is shown by different routes of administration: force-feeding, percutaneous, subcutaneous, intraperitoneal or intravenous injections. The potential for the biological control of mosquito and blackfly larvae is suggested.
This paper reports the experimental transmission of a bird parasite into jirds. Infective larvae of Cardiofilaria nilesi obtained from laboratory colonized Coquillettidia crassipes mosquitoes which had fed on an infected chicken were inoculated subcutaneously into jirds. The number of larvae per jird varied from 10 to 228. Microfilaraemia appeared 22 to 89 days after inoculation of the infective larvae. Experiments were carried out with 24 jirds through six generations extending over a period of 22 months and 17 produced patent infections. At present 8 infected jirds are being maintained in the laboratory; their patent periods ranging from 6 to 13 months. However, the longest patent period observed was about thirteen months. The percentage of adults recovered in autopsied jirds ranged from 0 to 40 with an average of 16. The chicken showed a microfilarial periodicity with the peak microfilarial density around 2200 hours. However, in jirds there was a change in sub-periodicity. This model in the jird may be very useful for the screening of filaricides and in immunological work.