Rapid and efficient removal of immature Aedes aegypti in metal drums by sweep net and modified sweeping method.

A modified sweeping method was developed using a cotton sweep net for control of Ae. aegypti immatures in 200 liter (44 gallon) metal drums which are major sources of breeding in Yangon. Laboratory experiments revealed that with only 4 sweeps (approximately 10 minutes duration), the mean % removal (+/- SD) of Ae. aegypti fourth stage larvae was 88.5% +/- 1.47. This was followed by a field study undertaken in Sanchaung township, Yangon. Twenty-eight drums with moderate (< 500 immatures) to high (> or = 500 immatures) Ae. aegypti density were tested in the field. It was found that with only 4 sweeps per drum, a total of 24,886 immatures were removed out of 29,155 immatures in these 28 drums, giving a mean % removal per drum of 85.36% +/- 10.74 (range = 55.54-98.62%). This sweeping method is simple, cost-effective, and readily accepted by the community. It could be an appropriate technology for control of the dengue hemorrhagic fever (DHF) vector Ae. aegypti.

The drug sensitivity patterns of Plasmodium falciparum in Myanmar (1990)

During 1990, sensitivity of P. falciparum to antimalarials was conducted in Mawlamyaing, Lashio and Seik Phyu townships. There were 40 successful in vitro test in Mawlamyaing, 39 in Lashio, 26 in Seik Phyu township. Chloroquine was found to be highly resistant (95 to 100 Percent) in Mawlamyaing and Lashio areas but 31 Percent sensitivity was detected in Seik Phyu township. Amodiaquine was found to be much more sensitive (38 to 67 Percent) than chloroquine. Effective concentration (EC99) for chloroquine varies from 7.4 to 8.4 U mol/L and EC99 for amodiaquine varies from 0.58 to 1.6 U mol/L. In all the areas studied sulfadoxine/pyrimethamine sensitivity was seen in 65 to 80 Percent. All the isolates from the three areas were 100 Percent sensitive to mefloquine and were also highly sensitive (93 to 100 Percent) to quinine. EC99 of quinine varies from 1.35 to 2.7 U mol/L and EC99 of mefloquine varies from 1.5 to 2.2 U mol/L in the areas.

The effect of chloroquine chemoprophylaxis on workers in Kazunma area

The study was conducted in November 1990 in the Kazunma village area of the Seikphyu Township. The study included 300 villagers of the Kazunma village as the control and the 315 workers of the Kazunma camps. The workers were on chloroquine chemoprophylaxis for more than three months. Among the villagers of the Kazunma village 16

were infected with malaria, P. falciparum 64.8

and P. vivax 31.3

. The malaria infection rate of the workers from the northern and the base camps were similar to the villagers. The workers from the southern camps have higher level of parasitaemia (26

) inspite of the chemoprophylaxis. Though the chemoprophylaxis has no effect on the parasite rate, it seems to have some effect on the parasite density of the workers of the northern and the base camps. The in vitro sensitivity of P. falciparum isolates were 30,8

sensitive to chloroquine and 55.6

sensitive to amodiaquine.

Experimental infection of laboratory animals with two "FIXED" rabies virus strains by different routes

Experimental infection of laboratory animals with two "fixed" rabies virus strains by different routes. By feeding guimea pig brains infected with the Standard Challenge Virus (CVS) rabies strain, 2 albino rats and 1 white mouse became Infected. Transmission was not effected by feeding CVS infected guinea pig tissues to either rats or mice. Feeding of CVS infected mouse brains did not produce infection in rats and mice. The mean mouse LD50 dose by intramuscular injection was 10 2.25 while the corresponding mean mouse l/C LD50 ,dose qf theCVS mouse brain suspensions used was 10 8.07 . Transmission of the Pasteur Variant (PV) rabies virus by gastric intubation of concentrated infective sheep brain suspensions in rats and mice was successful. In addition, mice could also be infected by exposure to aerosols of the same infective materials. the mean mouse intramuscular LD 50 dose of the brain suspensions was 18.5per cent. The mean mouse intracerebral LD5o of the infected materials used was 10-5.1. Virus was not transmitted to untreated white mice kept in contact with infected ones. Confirmation of rabies infection was done by either the WHO Mouse inoculation test and or the fluorescent Antibody Test (F.A.T).

Pre exposure prophylaxis of humans against rabies

The first batch of lyophilized, Sample-type,beta propiolactone inactivated anti-rabies vaccine produced by B,P .I. in 1971 was used to immuaize 55 B.P .I. workers previously unexposed to rabies and with no history of rabies vaccination. Three doses of 0.25 ml of the vaccine were given intradermally at one week intervals. Booster doses given on the 98th.' 392nd. and 592nd. Day after the first dose. Blood samples were taken and serum-virus neutralization (SN) tests were performed at varying time intervals after basic immunization and booster doses. Satisfactory antibody responses were obtained. The course of immunological response is presented in tabular and graphical form. This work was carried out from June 1971 to January 1973.

Active immunization against tetanus.I. Relative efficacies of the fluid and the adsorbed tetanus vaccines (Toxoids)

Non-immune workers of the Burma Pharmaceutical Industry (B.P.I.) were immunized with either the purified fluid or the purified adsorbed Purified Toxoid Aluminium Phosphate (PTAP) tentanus vaccines. The antigenic or immunizing potencies of these vaccines were measured by titrating the serum antitoxin of thesubjects at varying time intervals after the first, second and third doses of vaccine.Statistical analysis to determine the significance of difference in mean antitoxin titres was caarried out by the "t" test for small samples. The adsorbedvaccine was found to be superior to the fluid vaccine in respect of eaarlier initiation of active immunity after the first dose and ht production of a four to eight-fold higher mean antitoxin titre after the second and third doses of vaccine. This higher mean antitoxin titre also persisted at a therapeutically protective level for a longer period.