Comparing the potential effectiveness of interventions against coronavirus 2019 outbreak in the Lao PDR: a mathematical modeling approach / Lao Medical Journal

@#This is a policy brief article on the prediction of Covid-19 outbreak and its prevention and control for the possible second wave in the Lao PDR. Compartmental dynamic modeling was created to reflect the natural history of Covid-19. This included susceptible, symptomatic and asymptomatic states and recovery or death. The simulation was done for one year and with two scenarios: 1) high transmission level (R0=5.2) and 2) mid -transmission level (R0=2.0). The model output showed that the size of the outbreak depended on the transmission level, and could reach to 85% of the Lao population with high transmission scenario. However, disease burden was predicted to be smaller with the interventions. Among these, voluntary home quarantine was found to be the most effective, but the predication reverses in the mid-level transmission scenario. Social distancing is much more effective. If there are imported COVID-19 cases, a new wave could occur in two weeks to 2 months, depending on the size of pandemic and efficacy of the rest of interventions. Mid-level lockdown would result in new epidemic starting by July 2020, but the number of infected people would be less if travel bans and social distancing are maintaining. Only high-level lockdown would be able to stop community transmission in the country.

The efficacy of compression immobilization technique in retarding spread of radio-labeled Russell's viper venom in rhesus monkeys and 'mock venom' NaI131 in human volunteers.

The efficacy of the modified compression immobilization technique in retarding spread of radio-labeled Russell's viper venom in 3 rhesus monkeys (Macaca mulata) and "mock venom" NaI131 in 14 human volunteers was studied. 0.1 microgram of Russell's viper venom having 10 microCi radioactivity in 0.2 ml normal saline containing 0.5% bovine serum albumin was injected subcutaneously at the lateral aspect of the right hind limb of a rhesus monkey. A hand-tight bandaging of a rubber pad measuring 55 x 28 x 16 mm over the injection site and splinting effectively retard spread of radio-labeled venom for the entire length of time applied, although complete immobilization was not achieved. In human volunteers, application of a pad measuring 60 x 50 x 17 mm over the subcutaneous injection site of 20 microCi or 12 microCi/0.2 ml NaI131 with a hand-tight bandaging (60 +/- 10 mmHg) and immobilization of limb was found to be effective in retarding the movement of radioactive NaI131. These results suggested that the compression pads tried in this study effectively retard the spread of radio-labeled Russell's viper venom (MW ranging from 20,000-90,000) and radioactive NaI131 (MW 150) from the site of injection. Thus, it is highly likely that the present compression pad will be useful as a first-aid measure in Russell's viper bite victims.

Some variation in membrane proteins of erythrocytes obtained from subjects with thalassaemia trait and G-6-PD deficient genes

A total of 350 erythrocyte samples were screened for haemoglobin variant, G-6-PD deficiency and thalassaemia trait genes. Of these 104 samples were subjected to membrane protein analysis using SDS-PAGE electrophoresis and double straining with silver and Coomassie Blue. Membrane protein patterns of erythrocytes from subjects with a single genetic defect (i.e. either G-6-PD deficient or thalassaemia trait) were found to be similar to that of normals but those from subjects with double genetic defects (i.e. combination of G-6-PD deficiency and thalassaemia trait) had a significantly reduced content of spectrin, band 3 and glycophorin A.

Serum haptoglobin levels in Russel's viper bite victims

Serum haptoglobin levels of proven Russell's viper bite victims were studied at various time intervals after the bite. Although some degree of hemolysis was observed, there was no complete situation of haptoglobin with hemoglobin in these patients.This indicates that hemoglobinuria induced renal damage can be excluded as a major cause of Russell's viper venom nephropathy in systemicenvenoming patients.

Interrelationship among glomerular filtration rate, fractional sodium excretion and albuminuria in Russell's viper bite patients

The interrelationship among Ccr, FENa percent and Ualb were observed in 38 Russell's viper bite patients for 5-days clinical course. Degree of albuminuria had strong hyperbolic relation with glomerular filtration rate (Ccr) on day 1 after bite but not from day 2 onwards. The extent of albuminuria and fractional sodium excretion (FENa per cent) level was found to indicate the severity of renal insult. Albuminuria (Ualb) was associated with impaired Ccr and renal sodium handling. Ccr value below 40 ml/min or albuminuria (Ualb) above 2.07 g/24 hr on day 1 after bite was found in oliguric renal failure patients.

Heparin therapy in Russell's viper bite victims with impending dic (a controlled trial).

A controlled clinical trial of low-dose heparin was carried out in confirmed cases of Russell's viper bite. Twenty-eight patients with coagulable blood and serum FDP levels (more than 80 micrograms/ml) were included in the study. They were randomised to receive low-dose heparin in an initial dose of 50 units/kg body weight intravenously immediately after antivenom followed by a continuous infusion of 10 units/kg/hr in isotonic saline for 24 hours, or antivenom alone. Response to treatment was assessed clinically as well as by serial measurements of coagulation factors and biochemical variables. No features of systemic envenoming developed in any patient after treatment, but one patient in each group developed microscopic haematuria. No systemic bleeding or acute renal failure occurred in any patient. Recovery rate from the clotting defect was similar in the two groups, but in patients with initially very low fibrinogen levels there was a tendency for the heparin to restore fibrinogen faster than in comparable patients who did not receive heparin.

Patterns of acute renal failure in Russell's viper bite patients

Fifty-two patients with acute renal failure due to Russell's viper bite were studied. 34 patients had oliguric and 18 had non-oliguric types of acute renal failure. There was a higher incidence of complications such as gastrointestinal bleeding, renal angle tenderness and facial oedema in patients with oliguria. These patients also had a higher serum creatinine, fractional excretion of sodium and renal failure index when compared to polyuric patients. Mortality rate was about 32 per cent inpatients with oliguria in spite of peritoneal dialysis in 8 patients. No patients in the polyuric group needed dialysis and none died. The difference may be due to more severe renal lesions in patients with oliguric acute renal failure.

Endemic goitre in lowland Burma.

The problem of endemic goitre in Burma was thought to be confined to hilly regions and therefore goitre control programme has been focussed on these areas only. However, sporadic evidences accrued that there might also be pockets of endemic goitre in low-lying areas of the country. Goitre surveys and indepth study were carried out to determine the magnitude and nature of endemic goitre in lowland Burma. The overall goitre rate was 67% and the male:female ratio was 1:1.2. The findings of the study indicate that the problem of endemic goitre is also of public health significance in the lowland areas of the country. It is recommended that effective and appropriate intervention programmes be extended to these areas.

Iron balance in young Burmese women

Hb determination, packed cell volume, serum iron and total iron-binding capacity, menstrual iron loss and dietary iron intake were determined in 109 healthy young Burmese nurses. The mean Hb concentration was 12.8 g/100 ml, the mean serum iron 112.5 ug/100 ml, the mean menstrual blood loss 34.5 ml/per period, the mean menstrual iron loss 14.3 mg/per period, and the average dietary iron intake per head per day was 30mg by the food composite analysis method. When grouped according to amount of menstrual iron loss it was found that the mean Hb concentration did not differ but that the serum iron showed a statistically insignificant trend towards lower values in those with a higher loss. The 24-hour urinary excretion of iron after desferrioxamine injection was below 5oo u/g in 4 out of 7on whom it was done.

Amaemia in two Burmese villages

A mass haemoglobin (Hb) survey was done on a total of 1, 961 subjects from two villages: Shan-te-gyi in Insein district and Tu-ywin-bo in Myingyan district. 90 per cent and 80 per cent respectively of the population was covered. Blood film : mean corpuscular Hb concentration : serum iron; serum protein; serum, whole blood and red cell folates; Hb electrophoresis and osmotic resistance tests were done on adults with Hb less than 11g per cent. Stool examination for helminthic infestation and a dietary survey were done in both villages. The mena Hb value if 520 adult males was 14.08 g per cent (S.D.1.81) and that of 648 adult females was 12.335 g per cent (S.D.1.79). 50 per cent of the males, 34 per cent of the females and 55 per cent of the 793 children below 15 years were anaemic according to WHO criteria. Pregnancy and lactation are significant factors in lowering the mean Hb; the mean Hb of the pregnant group and lactating group being 10.86 g per cent (S.D.1.60) and 12.13g per cent (S.D.1.92) respectively, both of which are significantly lower than the mean Hb of the 12.58g per cent (S.D.1.67) of the non-pregnant, non-lactating group. However, the percent anaemic according to WHO criteria is 28 per cent and 42 per cent respectively in the pregnant and lactating group versus 33 per cent in the non-pregnant, non-lactating group. 47.1 per cent of the anaemic females and 28.60 per cent of the anaemic males had serum iron values below 50g per cent. There were only 4 cases of Thalassemia-E disease among the 117 anaemic adults tested. The stool survey on adults showed that only 4 out of 74 anaemics (5 per cent) and 5 out of 54 non-anaemic controls (9 per cent) had hookworm ova in Shan-te-gyi. Of 54 anaemics and 28 non-anaemic controls tested in Tu-ywin-bo, none had hookworm ova. In the village the iron intake was adequate according to the Interdepartmental Committee on Nutrition for National Defense (ICNND) standards.

Intestinal absorption in the Burmese

The xylose absorption test using 5g of xylose, the vitamin A absorption test, and the modified folic acid absorption test of Butterworth (1962) was performed on 55 apparently health Burmese adults, 41 subjects with recent diarrhea, and 7 subjects during diarrhoea. Among healthy Burmese (20 out of 55) 36 percent had subnormal xylose absorption (10-29 percent excretion) ; (3 out of 36) 8 percent had defective vitamin A absorption with 5 hour plasma vitamin A levels less than 150 g percent (9 out of 26) 35 percent had defective folate absorption with 5 hour urinary excretion less than 0.87 mg. Considerable variation in xylose absorption was found on repeating the test at one week intervals. Among subjects with recent diarrhoea (8 out of 41) 20 percent had abnormal xylose absorption (less than 10 percent excretion ) and (21 out of 41) 15 percent had subnormal xylose absorption (17 out of 30) 57 percent had defective vitamin A absorption ; and (20 out of 27) 74 percent had defective vitamin A absorption ; and (20 out of 27) 74 percent had defective folate absorption. The incidence of defective xylose, vitamin A and folate absorption was significantly higher in those with recent diarrheoa when compared with the healthy subjects. The incidence of impaired absorption of vitamin A and folate is higher in individuals with defective xylose absorption than in those with normal xylose absorption. Apparently, impaired small intestinal function exists in a considerable proportion of apparently healthy Burmese as revealed by defective xylose and to a lesser extent vitamin A and folate absorption. Also, that defective small intestinal function occurs during and up to one week after an acute episode of diarrheoa . The presence of predomin- antly leaf-shaped jejunal villi in Burmese subjects not suffering from diarrhoea is noted.

The assessment of iron stores

Urianary excretion of iron after administration of the iron chelating agent, Desferrioxamine-B, was investigated as a method of assessing iron stores. The test was performed on normals and on patients with iron deficiency anaemia and on 2 subjects with possibly high iron stores. The results indicate that this method will be useful for assessment of storage of iron.

Some aspects of anaemia of pregnancy in Burma

Hb. concentration was determined in 1,167 unselected pregnant women attending the ante-natal clinic of the Central Maternity Hospital, Rangoon. Hb. concentration, M.C.H.C., Hb. electrophoresis, serum iron level and iron binding capacity and serum and whole blood folate (L. casei) levels were determined in 48 anaemics and 109 non-anaemic controls from among 230 unselected, obsteretically normal, full-term pregnant women in the wards of the Central Maternity Hospital, Rangoon. Ratio of paired maternal and cord blood was also determined for Hb. serum iron, and serum folate.