Shock associated with dengue infection

TROPICAL PEDIATRICS

Shock associated with dengue infection I. C l i n i c a l a n d p h y s i o l o g i c m a n i f e s t a t i o n s o f d e n g u e h e m o r r h a g i c ] e v e r i n T h a i l a n d , 1964

Shock and death are rare in most uncomplicated viral illnesses. However, shock associated with dengue virus injection is a major cause o[ death among Southeast Asian children. Hypoproteinemia, a common finding in this series, appears to play an important role both in the genesis o[ the shock and in the patients" response to therapy. The pathophysiology of this severe mosquito-borne hemorrhagic [ever is discussed and an approach to therapy is outlined.

Sanford N. Cohen, M.D., "~ and Scott B. Halstead, M.D. WASHINGTON~

D. C. AND B A N G K O K ,

Tt~AILAND

fection with this serious medical and public health problem. 5-s Dengue fever, the classical manifestation of dengue virus infection, is recognized primarily in adults and is a febrile disease characterized by myalgia, arthralgia, bone pain, and leukopenia. It is only rarely complicated by vomiting or hemorrhages, and death is rare? On the other hand, dengue hemorrhagic fever is a childhood illness that is frequently associated with a hemorrhagic diathesis and vomiting. Myalgia, arthralgia, bone pain, and leukopenia are rare. Shock occurs on the third to the fifth day after onset in up to 70 per cent of cases and fatality rates have been as high as 40 per cent (Table I). Thus, there is little similarity between the two syndromes caused by dengue viruses, and the occurrence of shock clearly differentiates dengue hemor-

DENOUE H E l U O R R H A G I C fever has been a major cause of death among children in Southeast Asia since 1956. The first cases of dengue hemorrhagic fever in Southeast Asia were noted in Manila in 1953, and outbreaks have since been reported throughout the Indochina peninsula and the Indian sub-continent?, 2 I t was differentiated from the other hemorrhagic fevers (e.g., Omsk, Korean a) in 1956, when dengue viruses were isolated from a number of cases in the Philippines. 4 Numerous studies have since corroborated the association of dengue inFrom the Division o[ Biochemistry, Walter Reed Army Institute o[ Research, Washington, D. C., the Department o[ Virology, U. S. Army SEATO Medical Research Laboratory, Bangkok, and the SEATO Clinical Research Center, Bangkok eAddress: De;Oartment o[ Pharmacology, New York University School o[ Medicine, New ~}~ork, N. Y. 10016.

448

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4 49

T a b l e I. P e r c e n t a g e f r e q u e n c y of various clinical findings in Southeast Asian h e m o r r h a g i c fever ~ Country Thailand Re[erenee Number of cases Palpable liver Petechiae Palpable nodes Shock Vomiting Anorexia Arthralgia and/or myalgia

lo

121

131

1,559 63 30 -30 60 55

1l 400 86 88 8 38 35 --

69 45 73 -40 70 21

441 51 73 48 7 56 --

--

2

--

--

14 60 82 65 -20 70 55 5

Philippines 15 16 85 150 -3 38 59 ----61 66 26 49

Malaysia 17 I 18 70 46 30 63 54 39 20 17 0 20 61 50 61 --

--

69

9

11

Vietham 19 374 ---73 40 ---

*Series 14 and 18 report serologieally proved cases. T h e r e m a i n d e r are based upon clinical diagnosis alone.

T a b l e I I . C o m p a r a t i v e clinical findings in dengue fever a n d dengue h e m o r r h a g i c fever

Dengue [ever

Finding

Adult disease Frequent Hemorrhagic diathesis Rare Myalgia, arthralgia or bone pain Frequent Leukopenia Frequent Vomiting Rare Palpable liver Rare Shock Never

Dengue hemorrhagic

feuer Rare Frequent Rare Rare Frequent Frequent Frequent

rhagic fever f r o m dengue fever ( T a b l e II). T h e T h a i H e m o r r h a g i c F e v e r S t u d y Center was organized in o r d e r to: (1) s t u d y the p a t h o p h y s i o l o g y of the dengue h e m o r r h a g i c fever syndrome, a n d (2) evaluate a therapeutic regimen for serious cases. This p a p e r will present clinical studies on 149 patients seen in Bangkok, T h a i l a n d , d u r i n g the 1964 epidemic, a n d a discussion of the possible progression of physiologic changes which take place as shock develops. A suggested t h e r a p e u t i c regimen will be presented a n d discussed. MATERIAL

AND

METHODS

This r e p o r t is based u p o n studies of 70 m a l e a n d 79 female patients, ages 5 m o n t h s t h r o u g h 17 years ( m e d i a n age, 5 y e a r s ) , who

were a d m i t t e d to a special clinical research unit b e t w e e n J u l y a n d S e p t e m b e r , 1964. Patients were a d m i t t e d w h e n t h e y presented at the C e n t e r with a clinical s y n d r o m e suggesting dengue h e m o r r h a g i c fever. T h e crit e r i a u p o n which this diagnosis was m a d e in the clinic included: (1) history of vomiting a n d / o r anorexia, (2) fever, (3) l y m p h a d enopathy, (4) injected p h a r y n g e a l mucosa, (5) petechial rash, (6) positive tourniquet test, or (7) shock, all in the absence of obvious b a c t e r i a l infection. Shock was defined as either the absence of a d e t e c t a b l e blood pressure or a pulse pressure of less t h a n 20 mm. H g in the presence of cold, c l a m m y skin, t a c h y c a r d i a , restlessness, a n d stupor. T h i s diagnosis was confirmed b y at least two m e m b e r s of the m e d i c a l staff. Clinical methods. S t a n d a r d clinical chemistry m e t h o d s were a d j u s t e d for small q u a n tities of blood. H e m a t o l o g i c a n d bacteriologic studies were done by routine clinical l a b o r a t o r y methods. E l e c t r o c a r d i o g r a m s were t a k e n either on a S a n b o r n model "300" or a m o d e l "100" direct w r i t i n g machine. T o u r n i q u e t tests were p e r f o r m e d b y a p p l y i n g a blood pressure cuff to the a r m and m a i n t a i n i n g a pressure between the systolic a n d diastolic blood pressures for five minutes. T h e t e r m " h e p a t o m e g a l y " was a p p l i e d only when the liver edge was m o r e t h a n 2 cm. below the right costal m a r g i n . T h e level at which the h e m a t o c r i t stabilized d u r i n g recovery was used as an index of

4 50

March 1966

Cohen and HaIstead

each patient's normal hematocrit. T h e ratio Highest

hematocrit Recovery

-

Recovery

hematoerit

hematocrit

was computed to evaluate the degree of hemoconcentration in our patients. T h e one patient who bled enough to lower his hematocrit was excluded from this computation. A value of 0.2 or greater was considered to represent evidence of significant hemoconcentration. Serologic and virologic methods. One acute and two convalescent serum samples from each patient were tested by microhemagglutination-inhibition ( H I ) and complement-fixation (CF) tests by previously described methods. 7 All samples were tested with antigens prepared from suspensions of mouse brains which were infected with chikungunya, Ross strain (chik); dengue 1-4; T H - 3 6 (resembles dengue 2) ; and T H Sman (resembles dengue 1). A diagnosis of dengue infection was made if, during the period of observation, there was a fourfold or greater rise in dengue H I titer or a fixed titer of 1:640 or greater. Virus isolation studies were performed on the acute phase samples utilizing both suckling mice and tissue culture. The results of these studies will be reported separately.

RESULTS There were 149 patients in the series. Three patients died while under observation (2.0 per cent). The median hospital stay for the survivors was 6 89 days (range 2 to 25 days). All survivors were observed both in the hospital and again 7 to 14 days after discharge. Dengue infection was identified based upon serologic tests in 123 patients, or 82.5 per cent of the series. T h e 26 patients who did not meet the criteria for dengue infection were classified as having had a nondengue, viral illness and represent an internal control, since, in the absence of shock, patients were admitted by the same criteria. Five of these patients had serologic evidence of chikungunya infection, while no etiologic agent was identified in the remainder. The

clinical findings at the time of admission in our cases are summarized in Table I I I . Shock developed in 23 of the children with confirmed dengue infection (18.7 per cent) but in none of the controls. Nineteen of these patients were admitted in shock and 4 developed it while under observation. Shock is a complex phenomenon which is associated with a number of physiologic abnormalitiesY ~ Any evaluation of the pathophysiology of dengue hemorrhagic fever must therefore consider the shock patients separately to differentiate the changes that might be due to the dengue infection itself from those that are the result of the shock. A comparison of the incidence of the abnormal laboratory findings in the shock group with that in the nonshock dengue patients and the controls is shown in Table IV. The differences in the incidence of hyponatremia, acidosis, elevated urea N concentration and serum transaminase between the shock group and the nonshock dengue group are statistically significant, but there is no statistically significant difference between the incidence of these abnormalities in the nonshock dengue group and the controls. Proteinuria was not more frequent in either group, and was transient in all cases. Hemoconcentration was significantly more common in the shock group than in the nonshock dengue patients. There was no statistically significant difference between the incidence in the

Table I I I . The frequency of various clinical findings in 123 dengue and 26 non-dengue cases at the time of admission. Bangkok, 1964

Finding Palpable liver Hepatomegaly* Rash (all types) Petechial rash Palpable lymph nodes Injected tonsils and pharynx Anorexia Vomiting Shock

I Dengue [ Non-dengue 58.5% 6.5 % 56.9% 43.1% 72.4%

46.2% 3.8 % 53.8% 26.9% 65.4%

97.6% 90.2 % 66.7 % 18.7%t

100.0% 69.2 % 42.3 % 0.0%

*Liver edge at least 2 cm. below right costal margin. fIncludes four patients who developed shock after admission.

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451

patients, but only rarely went below 75,000 per cubic millimeter. Laboratory findings at the time of admission in the three patients who died during the course of this study are shown in Table VI, as are results of studies done just prior to death in these cases. Note that the abnormalities were generally identical with those that might be expected in patients with shock and that death was associated with a lethal level of serum potassium in all three cases. A comparison of electrocardiograms taken approximately 75 minutes apart illustrates the rapidity with which this hyperkalemia develops (Fig. 1).

nonshock group and the control cases. Hypoproteinemia was most common in the shock group, but was significantly more frequent in the nonshock dengue patients than in the non-dengue controls. Serum potassium and blood glucose concentrations were normal and only one child had transient hyperbilirubinemia. Admission electrocardiograms showed no abnormalities related to the acute illness in any patient. Group A, beta hemolytic streptococci were recovered from routine throat cultures in four cases and from a skin infection in a fifth. There was no bacteriologic evidence of either a systemic infection at the time of admission or of a serious bacterial complication during the period of treatment and convalescence in our series. There was depression of plasma clotting factors 5, 7, 9, and 10 in a few of the shock group, but the clotting mechanism, as measured by prothrombin and partial thromboplastin time, was rarely significantly disturbed (Table V). Platelet counts were depressed in m a n y

PATHOLOGY Postmortem examination was carried out in each of the three fatal cases. In all three there was edema and congestion of the soft tissues, especially in the retroperitoneal regions. There was evidence of intense reticuloendothelial activity in the lymph nodes, spleen, and thymus in all three, and there

Table IV. Frequency of various abnormal laboratory findings at the time of admission in 149 cases of hemorrhagic fever. Bangkok, 1964

Dengue (123) Shock (23) [ Nonshoek (100)

Control (26)

Sodium < 135 mEq./L. COs __ 15 m M . / L . (with acid urine) Serum urea N ~ 20 mg./100 c.c. SGOT > 150 S.F. units

65.5% 62.0% 62.0% 56.5%

16.0%

15.4% 11.5% 11.5% 3.9%

SGPT > I00 S.F. units Proteinuria > 2+ Hemoconcentration* Total serum protein _< 5.5 Gin./100 c.c.

30.5% 8.6% 95.5% (20) 78.5% (23)

8.1% 8.0% 31.7% (63) 31.0% (100)

0.0% 3.8% 11.8% (17) 7.7% (26)

Findine

16.0% 18.9%

22.0%

*Highest hematocrit - Recovery hematocrit > 0.2 Recovery hematocrit

Table V. Analysis of plasma clotting factors in dengue hemorrhagic fever. Frequency of abnormal levels in 57 cases. Bangkok, 1964 ~

Factor I (Fibrinogen)

II V VII VIII IX X

(Prothrombin) (Proaecelerin) (Proconvertin) (AHF) (Christmas) (Stuart-Prower)

[

Level (200

rag./100 c.c.

( ( ( ,~ ( (

50% 40% 50% 58% 50% 50%

]

Shock (16) 0

0 10.5% 31.3% 0 31.3% 25.0%

*Analysis done by Dr. Phumara Talalak, Siriraj Hospital and Medical School, Bangkok.

[ Nonshock (41) 0

0 0 0 0 0 0

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March 1966

Cohen and Halstead

T a b l e V I . L a b o r a t o r y findings in t h r e e fatal cases of dengue h e m o r r h a g i c fever. Bangkok, 1964 Patient No. 41

A~IB~

Finding

Sodium (mEq./L.) CO.- content (mM./L.) Serum urea nitrogen (mg./100 c.c.) Potassium (mEq./L.) Hematoerit (%) SLOT (S.F. units) SGPT (S.F. units) Total serum protein (Gm./100 e.c.) Interval between admission and ternfinal studies (hr.)

53

135.0 11.5 48.0 5.6 44.0 215.0 36.0 4.9

AI

132.0 7.2 32,0 12.0 47.0 740.0 128.0 4.5

133.0 12.1 27.0 5.7 39.0 159.0 46.0 5.6

13.5

80

B 133.0 16.7 24.0 12.5 44.0 2,955.0 980.0 5.3 10.0

AI 130.0 8.7 57.0 t 43.0 4,740.0 2,440.0 7.2

B 140.0 17.1 56.0 9.7 41.0 10,620.0 3,000.0 3.9 1.5

~A, at the time of admission; B, just prior to death. "~Hemolyzed specimen.

pneumonitis. These findings are similar to those n o t e d b y o t h e r investigators in Southeast Asia. TM 22 TREATMENT 9 ."

,

='==========;Fr===:==:========================:===::::

Fig. 1. The electrocardiogram in a fatal case of dengue hemorrhagic fever. Both tracings are from Lead II. The upper tracing was made at the time of admission. No serum K+ value is available due to hemolysis in the specimen. The lower tracing was taken 75 minutes later when the child's condition deteriorated. Serum K+ at that time was 12 mEq. per liter. The patient died 15 minutes after the lower tracing was made.

were h e m o r r h a g e s in l y m p h nodes in two. T h e r e were pleural, peritoneal, a n d peric a r d i a l effusions in each case a n d the livers all showed necrosis of i n d i v i d u a l p a r e n c h y m a l cells w i t h the f o r m a t i o n of C o u n c i l m a n like bodies. O n e child h a d a large, fresh, s u b a r a c h n o i d h e m o r r h a g e at the base of the b r a i n a n d all showed petechiae in the bowel m u c o s a a n d septal e n d o c a r d i u m . T h e r e was n a r r o w i n g of th~ zona glomerulosa in all three cases, b u t no evidence of a d r e n a l h e m o r r h a g e or inflammation. E a c h h a d a diffuse

Since no specific t r e a t m e n t is available, patients were given s y m p t o m a t i c , supportive therapy. Patients in shock, a n d all others who a p p e a r e d clinically d e h y d r a t e d , were given a r a p i d infusion of Ringer's lactate solution, followed b y a solution of one p a r t D a r r o w ' s K l a c t a t e solution a n d either two or t h r e e p a r t s 5 p e r cent glucose in water. All patients were assumed to be 5 p e r cent d e h y d r a t e d for the p u r p o s e of calculating initial r e p l a c e m e n t t h e r a p y . O x y g e n was a d ministered to all p a t i e n t s in shock, first by face m a s k a n d later in a c r o u p tent. O n c e the critical p e r i o d was over, they received routine m a i n t e n a n c e fluid t h e r a p y until they were well enough to begin a n o r m a l oral intakeY T h e 23 patients with shock fell into two subgroups based u p o n the course of their hypoproteinemia and hemoconcentration d u r i n g fluid r e p l a c e m e n t t h e r a p y . I n five patients, the a b n o r m a l i t i e s associated with shock were r a p i d l y c o r r e c t e d b y fluid a n d electrolyte t h e r a p y . I n all of these cases, the blood pressure r e t u r n e d to n o r m a l within several minutes a n d r e m a i n e d a t n o r m a l levels, while h e m a t o c r i t s decreased steadily until they stabilized at r e a s o n a b l e levels. I n

Volume 68 Number

Shock with dengue infection

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18 patients, however, hemoconcentration, as measured by the microhematocrit, persisted in spite of fluid replacement and the return of a normal blood pressure. A plasma protein solution r was added to the regimen in these cases and uniformly resulted in a decreasing hematocrit after one to two hours in the survivors. In the three fatal cases, death occurred too soon after such therapy was begun to evaluate its effect. None of the nonshock or control patients received plasma protein therapy. One child had hematemesis and relapsed into shock. This brief, acute hemorrhage occurred 18 hours after the initial shock episode and resulted in a sharp fall in hematocrit. It stopped spontaneously and the patient improved rapidly after a transfusion of whole blood. Physical restraints were used to control restless patients. Paraldehyde or chloral hydrate was given to a few children because of agitation. Fever was controlled by hydrotherapy or by a combination of hydrotherapy and orally administered acetaminophen.'~ Children with Group A, beta hemolytic streptococcal infection were treated with penicillin. No other medication was given to any patient. DISCUSSION

When dengue viruses were isolated from children with a severe, often fatal illness in 1956, it was thought that a new dengueinduced syndrome had appeared, a, 24 In fact, this was probably not a new syndrome, but rather the first contemporary recognition of a syndrome initially described in 1897. 25 Between the time of this first account of what we now call denglae hemorrhagic fever and the current outbreaks in Southeast Asia, there were several reports of a severe viral illness, characterized by a hemorrhagic diathesis a n d / o r shock and death which occurred in children in association with an epidemic of dengue fever. 2~-2s Cases of a

453

similar syndrome occurred in Thailand as early as 1950. 29 The clinical findings in our cases illustrate the fact that, in the absence of shock, a clinical diagnosis of "hemorrhagic fever" cannot be construed to mean "dengue hemorrhagic fever." M a n y nonspecific viral infections seem to be capable of producing an illness characterized by fever and a petechial rash or a positive tourniquet test. Shock and death, however, have been limited to dengue-induced illness in the countries of the Indochina peninsula? Thus it is essential to understand the physiologic changes which take place in Southeast Asian children with dengue infection. Hyponatremia, acidosis, azotemia, S G O T elevations, and hemoconcentration all occurred with similar statistical frequency among the control patients and the nonshock dengue group. It thus appeared that these alterations may represent metabolic changes due to infection of various etiology, rather than changes due to any specific viral illness. Since shock itself is frequently associated with the same physiologic abnormalities, it was not surprising to find that the shock group had the highest incidence of these findings. Though all of these abnormalities appeared to be nonspecific changes brought about by the acute febrile illness or by shock, even the nonshock dengue patients developed hypoproteinemia with greater frequency than the controls. Thus, the hypoproteinemia seemed to be a part of the syndrome of dengue infection itself. T h a t this hypoproteinemia was indeed related to the illness is indicated by the observation that the four children who developed shock in the hospital had acceptable serum protein concentrations at the time of admission and developed hypoproteinemia as their illness progressed. This was not a dilutional phenomenon in these cases, since their hemat0crits increased slightly over the same period of time (Fig.

2). .~Plasmanate 5 per cent plasma protein solution, Cutter Laboratories, Inc. tTylenol, McNeil Laboratories, Inc.

Major protein loss via the urinary and gastrointestinal routes appears to be an unlikely explanation for this hypoproteinemia.

454

z

Z5

March 1966

Cohen and Halstead

~115

v.o

#142

22 ~_O 6.5

# 126

Ix ~g6,o

~113

5.5 o

5.0 50 48 46

#142

44 42 *t

40 30 56 34 32

I S

I 4

I 5 DAY OF ILLNESS

I 6

I 7

I 8

Fig, 2. Hemoconcentration and hypoproteinemia in dengue hemorrhagic fever. All four of these patients developed shock while under observation in the hospital. Note that hemoconcentration and hypoproteinemia developed simultaneously in these patients and that both were present at the time shock was noted. (Arrow denotes time shock was

noted.)

Proteinuria was both transient and of insignificant degree. There was no change in bowel habits or in the character of the stools and there was no pathologic evidence of fluid pooling in the bowel wall or lumen. Malnutrition also appears unlikely as the explanation for the lowered total serum protein concentration because of the rapidity with which normal concentrations reappeared. Normal levels were found within six days after the lowest values were recorded in 48 of 49 cases. Since there is no evidence and little precedent to suggest that an alteration in the normal balance between protein synthesis and degradation occurred in our cases, it would appear that the hypoproteinemia was a result of a redistribution of protein brought about by the dengue infection. The serum protein concentration so frequently reflects the degree of hemoconcentration in human systemic disease that it is commonly used interchangeably with the hematocrit to evaluate changes in plasma volume. A dichotomy has been noted between these two parameters, however, after t r a u m a to experimental animals s~ and

after administration of guanidine hydrochloride to dogs. 33 This association of hypoproteinemia and hemoconcentration in shock experiments has been ascribed to fluid and protein shifts which occur when capillaries are damaged. 34 While hypoproteinemia occurs during yellow fever, s~ there is no precedent for the finding of a decreased total serum protein concentration in association with an increased hematocrit in acute viral illnesses. It has been noted, however, in rickettsial infection, s~,37 in rabbits given lethal doses of live anthrax bacilli intravenously, as and in monkeys given sublethal doses of staphylococcal enterotoxin by the s a m e route. 39 Hypoproteinemia appears to be important both in the genesis and in the therapy of the shock of dengue hemorrhagic fever. The dehydration produced by the dengue-induced anorexia and vomiting does not appear severe enough to lead to shock and death. It is therefore tempting to postulate the following sequence of events in the production of shock. Capillary damage, initiated by the dengue infection, allows protein and water to leave the circulation, thereby lowering the intravascular volume. Extracellular water, which is protein-poor, enters the vascular space to maintain the circulating volume, but lowers the protein concentration. The resultant lowered oncotic pressure reduces the movement of extracellular water into the vascular space. When the volume of extracellular fluid available for maintenance of the circulating volume has been previously reduced by dehydration, peripheral vascular collapse and shock occur. Acidosis and hypoxia perpetuate the shock and, when critical levels are reached, contribute to the rapid rise in extracellular potassium concentration and death. Hypoproteinemia adversely affects therapy by allowing administered fluids to leave the vascular compartment so rapidly that shock is not relieved. Under these circumstances, tissue edema is exaggerated and hemoconcentration persists. The observation that death was related to lethal hyperkalemia in our series m a y explain

Volume 68 Number 3

the failure of autopsy examination to reveal the cause of death in most cases. Sodium bicarbonate, glucose, and insulin and a single dose of calcium gluconate were all ineffective in maintaining the patients' cardiac function untiI ion exchange resin or peritoneal dialysis could reduce the level of extracellular potassium, Perhaps, as has been suggested for other hyperkalemic states, a constant infusion of the calcium salt might be appropriate emergency therapy for patients dying during hemorrhagic fever shock. Intravenous therapy, designed to relieve shock and acidosis should be the initial treatment of all cases of dengue hemorrhagic fever with shock. If the cycle that begins with dehydration and hypoproteinemia can be interrupted, the danger of a sudden release of intracellular potassium can probably be eliminated. The administration of adrenocortical steroids, vasoactive agents, hypnotics, and broad spectrum antibiotics should probably be avoided. Plasma or plasma protein solutions should be added to the therapeutic regimen whenever there is evidence of progressive hemoconcentration in spite of fluid replacement. Whole blood is probably contraindicated in states of hemoconcentration. Blood transfusions should be reserved for those patients who suffer major bleeding as evidenced by a falling hematocrit or hemoglobin. SUMMARY

1. Dengue hemorrhagic fever is a serious medical and public health problem throughout Southeast Asia. It affects children primarily and is a major cause of death in pediatric patients in the countries of that area. '2. Hypoproteinemia seems to play a role both in the development of shock during dengue hemorrhagic fever and in the patients' response to therapy. This hypoproteinemia may represent an effect of dengue infection itself and information on its frequency in patients with dengue fever is needed. 3. A planned program of fluid, electrolyte,

~'l~ock with dengue injection

455

and plasma protein therapy appears to prevent death in most instances. Therapy should probably be limited to such supportive measures, since there is no specific treatment for the syndrome. The authors are indebted to H. E. Phra Bamras Naradul, Minister of Public Health of the Kingdom of Thailand, for the assistance and support which made this study possible. We are also indebted to Lt. Gen. Prapakarn Karnjanakom, Maj. Gen. Pung Phintuyotin, Col. James L. Hansen and Drs. Boonsak Watanaphasook, Kamdhorn Suvanakich and Chajavan Osathanondh and their staffs for their cooperation and support. We would also like to thank Lt. Col. Mayuree Balankura, administrative director of the Center and Drs. Chaiyan Kampanart-Sanyakorn and Aree Valyasevi for their support in the planning and day-to-day operation of the Center. We are grateful to Dr. Charas Yammarat for his advice and friendship and to Drs. Malee Pakumphol, Ahpatorn Sudhasaneya, Pornrat Indrakoses, Paitoon Arayangkoon, and Mallika Tumrakdee for their dedication to the welfare of our patients, and to Dr. Suchinda Udomsakdi for the serologic data. Drs. Edward L. Buescher, Malcolm Artenstein and John Freeman gave unselfishly of their time in reviewing the manuscript and we appreciate all of their efforts. Thanks are due to Dr. Sylvanus W. Nye for doing the autopsies and to Drs. Supa Na-Nakorn and Phumara Talalak for the special hematological studies. REFERENCES

1. Halstead, S. B.: Mosquito-borne hemorrhagic fevers of South and Southeast Asia, Bull. World Health Organ. In press. 2. Report of the WHO Seminar on mosquitoborne hemorrhagic fevers in Southeast Asia and Western Pacific regions. WHO Regional Office for Southeast Asia, New Delhi, India, 1964. 3. Gajdusek, D. C.: Virus hemorrhagic fevers, J. P~DIAT. 60: 841, 1962. 4. Hammon, W. McD., Rudnick, A., and Sather, G. E.: Viruses associated with the epidemic hemorrhagic fevers of the Philippines and Thailand, Science 131: 1102, 1960. 5. Lim, K. A., Chan, Y. C., Phoon, W. O., and Hanam, E.: Dengue-type viruses isolated in Singapore, Bull. World HeaIth Organ. 30: 227, 1964. 6. Hammon, W. McD., and Sather, G. E.: Virologic findings in the 1960 hemorrhagic

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7.

8.

9.

10.

11.

12. 13. 14.

15. 16.

17.

18.

19.

20.

21.

Cohen and Halstead

fever epidemic (dengue) in Thailand, Am. J. Trop. Med. 13" 629, 1964. Halstead, S. B., Voulgaropoulos, E., Tien, N. H., and Udomsakdi, S.: Dengue hemorrhagic fever in Vietnam. Report of the 1963 outbreak, Am. J. Trop. Med. In press. Sarkar, J. K., Pavri, K. M., Chatterjee, S. N., Chakravarty, S. K., and Anderson, C. R.: Virological and serological studies of cases of hemorrhagic fever in Calcutta, Indian J. M. Res. 52: 684, 1964. Sabin, A. B.: in Hunter, G. W., Frye, W. W., and Swartzwelder, J. C., editors: A manual of tropical medicine, 3rd ed., Philadelphia, 1960, W. B. Saunders Company. Toochinda, P.: The clinical course of Thai hemorrhagic fever. Proceedings of the Thai hemorrhagic fever symposium, Bangkok, Thailand, 10 and 11 August, 1961, SEATO Medical Research Monograph No. 2: 101, 1962. Phitaksphraiwan, P., Nimmannitya, S., Rajvejpisan, V., and Prasatvinchai, S.: Clinical observations of Thai hemorrhagic fever in the Children's Hospital, Idem p. 88. Nelson, E. R.: Hemorrhagic fever in children in Thailand, J. PEDIAT. 56-" I01, 1960. Dasaneyavaja, A., and Pongsupat, S.: Observations on Thai hemorrhagic fever, J. Trop. Med. 64: 310, 1961. Margiotta, M., Nimmannitya, S., and Halstead, S. B.: Clinical manifestations of dengue hemorrhagic fever, J. PEDIAT. Submitted for publication. Qulntos, F. N., and Lira, L. E.: Philippine hemorrhagic fever. Clinical picture, Santo Tomas J. Med. 11: 319, 1956. Fabie, A. E.: Clinical aspects of Philippines hemorrhagic fever. Document IR/Haem. Fever/Sere. 1/WP 55 WHO Seminar on mosquito-borne haemorrhagic fever in Southeast Asia and Western Pacific regions. Bangkok, Thailand t9-26 Oct., 1964. Unpublished. Chew, A., Gwee, A. L., Ho, Y., Khoo, O. T., Lee, Y. K., Lira, C. H., and Wells, R.: A hemorrhagic fever in Singapore, Lancet 1: 307 1961. Goldsmith, R. S., Wong, H. B., Paul, F. M., Chan, K. Y., Lob, T. F., and Chan, Y. C.: Hemorrhagic fever in Singapore, Lancet 1: 333, 1965. Thoa, V. T.: Clinical observations on mosquito-borne hemorrhagic fever in the Saigon Children's Hospital. A report of 374 cases. Document IR/Haem. Fever/Sere. 1/WP 56 WHO Seminar on mosquito-borne haemorrhagic fevers in Southeast Asia and Western Pacific Regions. Bangkok, Thailand 19-26 October, 1964. Unpublished. Levenson, S. M., Einhaber, A., and Maim, O. J.: Nutritional and metabolic aspects of shock, Fed. Proc. 20: (Suppl. No. 9); 99, 1961. Piyaratn, P.: pathology of Thailand epidemic hemorrhagic fever, Am. J. Trop. Med. 10: 767, 1961.

March 1966

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