305

THE DIAGNOSIS OF VIRUS INFECTIONSBy D. GERAINT JAMES, M.B., M.R.C.P.

Senior Medical Registrar, The Middlesex Hospital, W. i

With the advent of specific chemotherapy,precise diagnosis is important in the efficientmanagement of virus infections. The sulphon-amides were known to be of use against the virusesof lymphogranuloma venereum (Findlay, I940),inclusion conjunctivitis (Thygeson, I94'; I942),and trachoma (Loe, 1938); penicillin was shownto have some effect against the-virus of psittacosis(Bedson and May, I945; Heilman and Herrell,I944). The development of the so-called newerantibiotics-aureomycin, terramycin and chlor-amphenicol-which are effective against a widerrange 'of virus and rickettsial. infections, suggeststhat other as yet undiscovered substances mayeventually control all diseases due to viruses andrickettsiae.The diagnosis of some viral infections can be

made at the bedside; others require close co-operation between the clinician and laboratoryvirologist. Each plays an important role in themanagement of the case, and so in the subsequentwelfare of the community. The clinician, fromthe history, epidemiological data and clinicalfindings, may narrow the differential diagnosisor indeed reach the correct diagnosis. Thelaboratory worker may confirm the diagnosis byisolating the aetiological agent, by showing aspecific immunological response, or by demon-strating characteristic pathological changes in thepatient's tissues.To improve this co-operation the clinician

must know the laboratory worker's requirementsin any given case; he must know which are themost appropriate specimens, the optimum stageof the disease for their collection, and the value ofpaired acute-phase and convalescent sera fordemonstrating rising antibody titres.

The Physician's Role(a) History.(b) Clinical findings.

(a) History. Indications of importance indiagnosis are: the prevalence of a certain diseasein the community, the seasonal incidence ofcertain viral infections, or a history of contactwith rabid dogs, infected syringe needles (hepa-titis), sheep and horses (encephalitis), mice(lymphocytic choriomeningitis) or arthropods(rickettsiae). Viral and rickettsial diseases are

usually spread by direct contact, air-borne drop-lets, or arthropod vectors. Unlike bacterial in-fections, water-borne and food-borne epidemics,apart from infective hepatitis and possibly polio-myelitis, are relatively uncommon.

(b) Clinical Findings. The exanthemata arecharacterized by a skin eruption which appears inthe prodromal or acute phase of the disease.Measles, German measles, smallpox and chicken-pox, which are of viral origin, are infectiousdiseases of this type. Herpes simplex and herpeszoster are other examples in which eruptive skinlesions are usually characteristic.

If all viral infections had such outstandingcharacteristics, laboratory help would be un-necessary in diagnosis. Such is not the case, forinstance, in the diagnosis of the viral pneumoniaswhich are aetiologically distinct but clinicallyindistinguishable. Virus pneumonia can be causedby the viruses of influenza A and B, psittacosis,lymphocytic choriomeningitis and the rickettsiaof Q fever, as well as the unidentified virus (orviruses) of the so-called ' primary atypical pneu-monia.' In such an example the diagnosis can onlybe made with the help of a laboratory. Similarly,a better understanding of the various encephali-tides, which are clinically indistinguishable (asare the benign aseptic meningitides), can only beobtained by recourse to the laboratory.

It is often assumed that the white blood cellcount is a reliable index for differentiating viralfrom bacterial infections. Bacterial infections areusually accompanied by a polymorphonuclearleucocytosis, whereas viral infections are associatedwith a normal white cell count or perhaps a relativelymphocytosis. Occasionally, however, the whitecell count is misleading. Encephalitis, lympho-cytic choriomeningitis, and primary atypicalpneumonia may be accompanied by a polymor-phonuclear leucocytosis, whereas mild or ful-rninating bacterial infections may show a norma'lwhite cell count. Furthermore, associated viraland bacterial infections which occur commonly inthe respiratory group make this rule-of-thumbeven more misleading. Today; probably thecommonest source of confusion with viral pneu-monia is the inadequately treated bacterialpneumonia, in which the offending pneumococcushas been masked by small amounts of antibiotic.

POSTGRADUATE MEDICAL JOURNAL

The varying clinical manifestations of the Cox-sackie virus are worth stressing because theyenter into the differential diagnosis of benignaseptic meningitis, non-paralytic poliomyelitis,acute pleurisy, coronary thombosis, the actiteabdomen and vesicular tonsillitis. Coxsackie isa village on the banks of the Hudson River inupper New York State. During an outbreak ofpoliomyelitis there in 1947, Dalldorf and Sickliesisolated a virus, distinct from that of poliomyelitus.In the last three years, much interest has beenfocused on this virus, and the present knowledge ofits relation to Bornholm disease is due to closeco-operation between clinician and virologist.Its precise role as a causative agent in disease isdifficult to assess. Dalldorf has rightly said thatwe are in the anomalous position of having dis-covered the cause before the disease. Suchinfection should be borne in mind in the diagnosisof the clinical pictures mentioned above.

The Laboratory RoleThis resolves itself into (i) isolation of the

virus from the patient, (2) serological tests toshow iminunological responses on the part of thepatient and (3) the demonstration of characteristicinclusion bodies in the patient's tissues.

(i) Isolation of the Virus. This is often difficult,time-consuming or impossible. Such work,which is undertaken in special virological units,is not possible in routine hospital laboratories.The clinician, however, should know the diseasesin which isolation of the virus can be undertakenconveniently, what specimens are needed and howthey should be packed.The viruses of influenza A and B, mumps and

herpes simplex are recoverable early in the diseasefrom throat washings, saliva and vesicle fluid,respectively.The early identification of the virus responsible

for an influenzal outbreak is important, forepidemics may be transmitted by international airtravel. Throat washings should be obtained asearly as possible in the disease, using a broth orsaline gargle. The patient should cough beforegargling, so that infective bronchial material isincluded in the specimen. Penicillin (500 units!ml.) is added to suppress bacterial growth. Theamnion of fertile hens' eggs is inoculated with thisthroat washing. If there is a delay, or for trans-port, the specimen should be frozen in a thermosflask packed with carbon dioxide snow. A resultmay be obtained in 2-4 days. The infected,amniotic fluid agglutinates chick and humanerythrocytes and this haemagglutination can beinhibited by appropriate Influenza A or B specificantisera (Hirst, I942).A clinical diagnosis of mumps usually renders

examination of saliva for virus unnecessary. Thevi;rus is recoverable from the spinal fluid in mumpsmeningd-encephalitis; this has been done inpatients without parotitis on the second day ofillness (Henle and McDougall, 1947). It is foundthat some cases of benign aseptic meningitis aredue to the mumps virus (Kane and Enders, I945).The best results are obtained by inoculatingfertile hens' eggs as soon as possible after obtain-ing the fluid, but if necessary it can be frozen andkept until the results of other investigations areavailable. Diagnosis may be made within four toseven days, using the haemagglutination pheno-menon mentioned above and the appropriateimmune serum.The herpes simplex virus may affect the skin

(herpes simplex, Kaposi's eczema herpeticum),muco-cutaneous junctions (herpes labialis, pro-genitalis and vulvo-vaginitis), mucous membranes(gingivo-stomatitis), eye (conjunctivitis) and cen-tral nervous system (meningo-encephalitis). Iden-tification of the virus may be of clinical importancein such cases. It has been isolated from mouthlesions (Dodd, et al., I939), brain (Smith, et al.,1941), spinal fluid (Armstrong, 1943), skin lesions(Ruchman, et al., 1947) and blood (Scott, et al.,I949). Specimens may be used directly or storedin phosphate-buffered saline pH 7.2 with i percent. gelatine, treated with penicillin 500 units/ml.Storage during transfer should be in a carbondioxide snow container as with other viruses.Isolation of the virus is made by inoculation ofthe chorio-allantoic membrane of the fertile hen'segg, inoculation of the scarified cornea of rabbitsor intracerebral inoculation in rabbits. A resultmay be obtained in two to seven days.

Isolation of the viruses of poliomyelitis, infectivehepatitis and the Coxsackie virus can be under-taken from specimens of faeces, but results arenot available sufficiently quickly to be of diag-nostic value in an individual case. They are, atpresent, of epidemiological and research interest.A complement-fixation test for smallpox, using

vesicle fluid as antigen and potent anti-vaccinialserum as antibody, may help to prove the diag-nosis early in this disease. Material from severallesions should be submitted, and a result can beanticipated within 24 hours (Craigie and Wishart,1936; Downie, 1946).

(2) Serological tests to show an immunologicalresponse on the part of the patient are easier toperform, quicker, and give satisfactory results inmany virus diseases. These tests are usuallyemployed in confirming the clinical diagnosis.They depend upon the demonstration of risingtitres of specific antibodies in convalescent, ascompared with acute-phase sera, but they sufferfrom the disadvantage that it is necessary to wait

306 May 1952

May 1952 JAMES: The Diagnosis of Virus Infections 307

for convalescent serum. Thus the diagnosis isoften retrospective, although high-acute-phaseserum titres may be a helpful provisional guide.

Serological methods employed are:(a) The in vitro complement-fixation test, using

virus antigen.(b) The in vivo animal neutralization test.(c) The in vitro haemagglutination-inhibition

test.(d) Non-specific tests.(a) The in vitro complement-fixation test. Potent

virus antigen is titrated against serial dilutions ofthe patient's serum; the highest dilution of serumin which complement is fixed is the end-point.A fourfold or greater increase in titre in the con-valescent, as compared with the acute-phaseserum, constitutes a significant antibody response.A typical result (after Horsfall, 1950) shows:

Serum :I0o 1:20 I:40 i:8o I:I60 I:32o TitreAcute + o o o o o I:IoConvalescent + + + o o o 1:40

+ --complement fixationo =no complement fixation

This experiment shows a two-tube, or fourfold,increase, which is significant. Such tests have theadvantage that they can be performed in anylaboratory where Wassermann tests are under-taken, without recourse to animal work. Theyare helpful in typhus (epidemic, murine andscrub); the encephalitides (distinguishing St.Louis, Japanese B and equine types); psittacosis,lymphogranuloma venereum, Q fever, lympho-cytic choriomeningitis, mumps, influenza A andB, and Coxsackie infections.

(b) The in vivo Animal Neutralization Test.Animal neutralization tests depend upon thecomparative powers of the patient's acute-phaseand convalescent sera to neutralize the appropriateviral disease in a number of test animals. Severalgroups of animals are infected with the standardvirus, and each group is inoculated with varyingdilutions of the patient's serum. The survivalrate in the varying groups is an index of theamount of antibody in the serum. This methodis employed only when absolutely necessary,because of the cost and complexity of the experi-ment. It is impractical for routine hospital use,but remains an important research tool. For thediagnosis of some viral diseases it is essential,because the simpler in vitro complement-fixationtest has not been developed.

Typical result (after Horsfall, 1950):Serum I:IO 1:20 I:40 I:8o I:I6o TitreAcute S D D D D I:I0Convalescent S S S S D i :8o

S=animals survivingD=animals died

There is a significant increase in titre, indicatinga rise in antibody in convalescent compared withacute-phase serum.

This method is employed with the viruses ofherpes simplex and yellow fever.

(c) The in vitro Haemagglutination-Inhibition Testis easy to perform, but is useful only in influenzaand mumps. It depends upon the ability of thepatient's serum, containing antibody, to inhibithaemagglutination by influenza and mumps virus.The patient's serum, in varying serial dilutions,is used and the highest dilution which inhibits theagglutination is taken as an end-point. Thereshould be at least a fourfold increase in titre inthe convalescent as compared with acute-phaseserum. Typical result (after Horsfall, 1950):Serum 1:10 I:20 1:40 i:8o I:I60 1:320 TitreAcute o + + + + + i:ioConvalescent o o o o + + :80

o =haemagglutination inhibited+ =haemagglutination

The acute-phase serum has prevented haemag-glutination at I: Io, whereas the convalescentserum inhibited agglutination at I: 8o. 'Thisindicates a significant increase in titre of antibody.With all these serological tests, it is important

to remember to collect blood as early in the diseaseas possible, and again two or three weeks later.About 6 ml. whole blood is sufficient. This isspun in the centrifuge, and the serum stored ina refrigerator at 4° C. until used.

(d) Non-Specific Tests. There are three diseasesin which non-specific tests are useful: infectiousmononucleosis, primary atypical pneumonia andtyphus.

Infectious Mononucleosis. Apart from a charac-teristic blood count in infectious mononucleosis,the majority of cases develop heterophile anti-bodies which agglutinate sheep red blood cells(Paul and Bunnell, 1932; Bunnell, I933). Thetest is positive in about 70 per cent. of cases bythe second week of the disease, but may bepositive in the first few days. Five ml. blood iscollected and centrifuged to obtain the serum.Normal blood may contain sheep red cell agglu-tinins, which are also present in serum sicknessin significant titres, and in people who havereceived horse serum injections. In order toavoid errors, it is well to remember the differentialadsorption of these agglutinins by guinea-pigkidney and beef red blood cells (Stuart et al.,I936).

InfectiousAdsorbed by Mono- Serum Normal

nucleosis Sickness SerumGuinea pig kidney ++-Beef R.B.C. + +

POSTGRADUATE MEDICAL JOURNAL

These heterophile antibodies are also presentin the spinal fluid of cases of infectious mono-nucleosis (Silberstein et al., I948).

Primary Atypical Pneumonia. During WorldWar 2 several groups of workers independentlyobserved the occurrence of cold haemagglutininsin primary atypical pneumonia (Peterson et al.,1943; Turner, '943; Turner et al., I943;Shone and Passmore, I943). In the absence of anyspecific tests, this phenomenon is at present ofsome diagnostic help, especially when it fits in witha suggestive clinical picture. The patient's serumagglutinates human (and various animal) red bloodcells at o to 50 C., and agglutination is absent at370 C. unless the titre is very high.

Cold haemagglutinins appear during the secondweek of the pneumonia, and decline during thefirst or second month after the onset. Titresshould be performed at weekly intervals becausea rising titre is more significant than a stationarylevel. Repeated examinations may show thepresence of cold haemagglutinins which wouldotherwise remain undetected. Kneeland (1951)has observed that they may be extremely transient,as in one case where they were absent two daysbefore and two days after a significant titre ofI: 5I2.There seems to be a rough correlation between

the titre of haemagglutination and the severity ofthe illness; high titres being associated with alonger duration of fever (Finland et al., I945;Laurell, 1948), and a more extensive pulmonaryinvolvement (Jordan et al., 195I).

It is important that blood be kept warm in anincubator until centrifuged, otherwise some ofthe agglutinin will be lost with the patient's redcells. Five ml. blood is sufficient for the estima-tion. Serial dilutions of serum are titrated againsta fresh o.5 per cent. suspension of human Group 0red cells. Since significant titre varies with indivi-dual laboratories, it should be ascertained whetherthe result is expressed as the original dilution ofthe serum or as the tfinal dilution after the redcell suspension has been added.

Agglutination may be detected on the rim ofthe syringe when blood is taken from the patient;or it may be suspected because of difficulty inperforming a blood count. This clue led to theirdetection by Turner in the epidemic in southernEngland in 1943.About 44 per cent. of cases of primary atypical

pneumonia show the phenomenon of 'strepto-coccus M.G. agglutination' (Horsfall, i947).This is a further non-specific test of some diag-nostic value. The serum of such cases agglutinatesthis non-haemolytic streptococcus. Serum fromS nl. of acute-phase and a further 5 ml. of con-valescent blood is sent to the laboratory. A four-

fold increase in titre is significant. This testresembles the Weil-Felix reaction, in that bothdepend upon the non-specific agglutination of abacterium by the patient's serum.

Typhus. The Weil-Felix reaction is a simpleand useful test which helps to confirm the diag-nosis of epidemic, murine and scrub typhus.Serial dilutions of the patient's serum are mixedwith constant amounts of B. proteus of the OX I9,OX 2 and OX-K strains. The result is expressedas the highest dilution which causes aggregationof these test suspensions:

Epidemic typhusMurine typhusScrub typhus

OX 19++++

OX 2 OX-K00

0 0 +++ = agglutinationO=no agglutination

(modified from Plotz, 1946)

The table summarizes the results obtainable inthe different varieties of typhus. It. is seen thatepidemic and murine typhus cannot be differen-tiated by this test. The test is of great value inepidemic and murine typhus because agglutininsfor OX I9 develop as early as the fifth to eighthday. Results for scrub typhus become positivein the second week, and help to confirm theclinical diagnosis, in an endemic area, of primaryeschar and a rash appearing on the fifth day offever. The test is negative in Q fever.

(3) Inclusion bodies. Specific anatomical changesin the patient's tissues are characteristic of certainvirus infections. These intracytoplasmic or intra-nuclear inclusion bodies are found in chickenpox,smallpox, herpes zoster, herpes simplex, psittacosisand lymphogranuloma venereum, inclusion con-junctivitis and trachoma, rabies and yellow fever.At one time these bodies were of great diagnosticimpertance, but they have now to a certain extentbeen superseded by serological tests.However, an examination of scrapings from the

base of vesicles in cases of smallpox, chickenpox,herpes zoster and herpes simplex, and frorm theconjunctiva in trachoma and inclusion conjunc-tivitis, may help to establish an early diagnosis.Smears in cases of chickenpox, herpes zoster andherpes simplex show identical features, which arecharacteristic but quite distinct from other vesi-cular diseases of the skin. They show greatlyenlarged giant multinucleated epithelial cells, fnwhich the normal chromatin granules and nucleoliare absent. The nuclei (stained with Giemsastain) contain reddish-violet stringy amorphousmaterial, and green melanin granules are seen ina blue-staining cytoplasm (Blank et al., 195 ).These characteristics are not seen in smallpox.Instead, smears from cases of smallpox; when

May 1952308

May 1952 JAMES: The Diagnosis of Virus Infections 309

stained by Paschen's method, show enormousnumbers of elementary bodies (van Rooyen andIllingworth, I944).The cytoplasmic inclusion bodies of trachoma

and inclusion conjunctivitis are morphologicallyidentical, but in trachoma they are more numerouson the upper tarsal conjunctiva, whereas thereverse holds for inclusion conjunctivitis (Braley,I940).Autopsy may reveal inclusion bodies in the liver

in yellow fever, and Negri bodies in the hippo-campus in rabies.

INCLUSION BODIES

Intra- Intra-Disease nuclear cytoplasmic Tissue in which found Staining characters

Chickenpox + Occasionally Skin lesions Acidophilic

Smallpox + Skin lesions Acidophilic

Herpes zoster + Occasionally Skin lesions Acidophilic

Herpes simplex + Skin lesions, nerve cells Acidophilic

Rabies + Nerve cells AcidophilicYellow fever + Liver cells Acidophilic

Psittacosis + Alveolar exudate, hilar lymph Basophilicglands, Kupffer cells, spleen Castaneda+

Lymphogranuloma venereum + Buboes

Inclusion conjunctivitis + Conjunctiva of lower tarsus LMatrix shows posi-( tive glycogen

Trachoma + Conjunctiva of upper tarsus _J stain

SkinT6sts

Intradermal tests with virus antigen have beenused in the diagnosis of individual cases, as wellas in community surveys for epidemiological data.The difficulty attendant upon this method hasbeen in preparing antigens free from impurity,which are sufficiently potent to give a specificreaction. The most popularly used is the Freitest. Frei prepared his original antigen from bubopus in cases of lymphogranuloma venereum (Frei,1925). It was, diluted in saline and inactivated byheat. Today the most potent antigen is preparedfrom lymphogranuloma virus grown in the yolk-sac of fertile hens' eggs. The final preparationis called lygranum (Grace et al., I940): O.1 ml.is injected intradermally into the skin of oneforearm, and a similar amount of uninfectedyolk-sac suspension as control into the other.Readings are made at two and again at four days.A raised inflammatory papule, at least 7 mm. indiameter, -compared with a negative response in

the control, is an index of a positive reaction. Apositive response means that the patient is, orhas been at some time in his life, infected withthe viruses of the psittacosis-lymphogranulomagroup; it is no more specific than this, and shouldtherefore be evaluated in the light of the clinicalpicture and serological results.

Skin tests have been used in mumps (Enderset al., I945, 1946), but are unsatisfactory. Theyare being used in herpes simplex (Rose and Molloy,1947) and infective hepatitis (Henle et al., 1950).but their value is at present uncertain.

ConclusionCertain points of practical value in the diagnosis

of virus infections should be stressed:(X) Specimens for virus isolation should not be

sent through the post. They should be placedimmediately on ice or in a thermos flask containingcarbon dioxide snow, and should be taken as soonas possible to the appropriate laboratory.

(2) Virus isolation is not a routine procedureand should only be considered in suitable cases.Serological methods form the backbone of virusdiagnostic procedures. Acute-phase serum shouldbe taken as early as possible in the disease, anda second specimen two or three weeks later.Such specimens can be despatched by post.

(3) A fourfold or greater increase in titre ofantibodies is significant. Such a finding shouldbe correlated with the clinical picture in an assess-ment of the case.

(4) Blood for cold agglutinins should be centri-fuged whilst warm, so that the patient's red cellsdo not precipitate any of the serum cold agglutinin.

310 POSTGRADUATE MEDICAL JOURNAL May 1952

'Incuba-Disease Virus Virus recover- Serological tests Inclusion bodies in tion

grown in able from period(days)

Mumps Fertile hens' Blood, saliva, (a) Haemagglutination in- i 8eggs C.S.F. hibition test

(b) Complement-fixationtest (C.F.T.)

Chickenpox - Vesicles 12-I6(varicella)

Smallpox (variola) Fertile eggs Vesicles, pus- C.F.T. using vesicle fluid Vesicles 12tules

German measles Monkeys Blood, naso- - I6-i8(rubella) pharynx

Measles Monkey, Nasopharynx, - - 11-I4man blood

Herpes simplex Fertile eggs Vesicles, Animal neutralization, Vesicles 3saliva, using acute and con-C.S.F. valescent sera

Herpes zoster Vesicles 7-14

Influenza Fertile eggs Nasopharynx (a) Haemagglutination in- 1-2Mice hibitionFerrets (b) C.F.T.

Common cold Chimpanzee*Man* Nasopharynx Up to 3Fertile eggs**

'Primary atypical - - (a) Cold haemagglutina- - Up to 21pneumonia' tion

(b) Strep. M.G.

Q fever Fertile eggs Nasopharynx, C.F.T. - I9blood

Psittacosis Fertile eggs Nasopharynx, C.F.T. Lungs, spleen 4-15(ornithosis) blood lymph glands

Lymphogranu- Fertile eggs Buboes C.F.T. Gland or granu- 3-2Iloma venereum loma

Hepatitis(a) Infective Mant Blood, faeces Up to 40

Fertile eggstt(b) Serum Man only Blood Up to i8o

Infectious (a) Blood picture 5-I0mononucleosis - (b) Paul-Bunnell

BIBLIOGRAPHYARMSTRONG, C (I943), Pub. Health Rep., 58, I6.BEDSON, S. P., and MAY, H. B. (I945), Lancet, ii, 394.BLANK, H., BURGOON, C. F., BALDRIDGE, G. D.,

McCARTHY, P. L., and URBACH, F. (i9si), Y. Amer. med.Ass., 146, 1410.

BRALEY, A. E. (I940), Arch. Ophthal., 24, 68x.BUNNELL, W. W. (I931), Amer. -7. med. Sci., I86, 346.CRAIGIE, J., and WISHART, F. 0. (1936), Canad. Pub. Health .7.,

27, 371.DALLDORF, G., and SICKLES, G. M. (1948), Science, xo8, 6I.DOCHEZ, A. R., SHIBLEY, G. S., and MILLS, K. C. (1930),

Y. exper. Med., 52, 701.DODD, K., BUDDINGH, G. J., and JOHNSTON, L. (1939),

Amer. J7. Dis. Child., 58, 907.DOWNIE, A. W. (1946), Month. Bull. Min. Health Emerg. Pub.

Health Lab. Service, 5, 114.DRAKE, M. E., KITTS, A. W., BLANCHARD, M. C.,

FARQUHAR, J. D., STOKES, J. Jun., and HENLE, W.(0950),.7 exper. Med., 92, 283.

ENDERS, J. F., COHEN, S., and KANE, L. W. (1945), Ibid8I, 119.

ENDERS, J. F., KANE, L. W., MARIS, E. P., and STOKES,J. Jun. (1946), Ibid., 84, 34I.

FINDLAY, G. M. (1940), Brit. J3. exper. Path., 21, 356.FINLAND, M., PETERSON, 0. L., ALLEN, H. E., SAMPER,

B. A., and BARNES, M. W. (1945), J. clin. Invest., 24, 458.FREI, W. (1925), Klin. Wschr., 4, 2148.GRACE, A. W., RAKE, G., and SHAFFER, M. F. (1940), Proc.

Soc. eXPer. Biol. Med., 45, 259.HEILMAN, F. R., and HERRELL, W. E. (I944), Proc. Mayo

Clin., 19, 204.HENLE, G., and McDOUGALL, C. L. (I947), Proc. Soc. exper

Biol. Med., 66, 209.HENLE, G., DRAKE, M. E., HENLE, W., and STOKES, J. Jun.

(I950), Ibid., 73, 603.HENLE, W., HARRIS, S. HENLE, G., HARRIS, T. N.

DRAKE, M. E., MAN6OLD, F., and STOKES, J. Jun.(1950), Y. exper. Med., 92, 27x.

May I952 JAMES: The Diagnosis of Virus InfectioWs II

Incuba-Virus Virus recover- tion

Disease grown in able from Serological tests Inclusion bodies in period(days)

Lymphocytic Mice Blood C.F.T. I --3 dayschoriomenin- Guinea-pigs C.S.F. experi-gitis mental

infec -

notknown

innatural

Poliomyelitis Monkeys Faeces, naso- 4-35pharynx

Epidemic myalgia (a) suckling Nasopharynx, C.F.T. ProbabIy(Bornholm mice faeces about 5

dis.) (b) adultmiceon cor-tisone

Encephalitis St. Mice Blood, brain, (a) C.F.T. 4-2 ILouis; Western Fertile eggs C.S.F., (b) Animal neutralizationand Eastern spinal cord testsequine; loup-ing ill)

Rabies Mice, rabbits Saliva, brain, Negri bodies in io daysdogs spinal cord hippocampus to 7

months

Typhus Guinea pigs, Blood (a) Weil-FelixFertile eggs (b) C.F.T. 8-i8

(c) Agglutination

Yellow fever Mice, Blood Animal neutralization Liver 3-6monkeys

Trachoma and Man, Conjunctiva C.F.T. using psittacosis- Scrapings from tar- 4-12inclusion con- monkey L.G.V. antigens may sal conjunctivajunctivitis be positive because of

antigenic similarity

Dengue Man, mice, Blood Mouse neutralization tests 5-9fertile eggs

Sandfly fever Man Blood - 2j-6*Dochez et al. (1930). **Kneeland et al. (1936). tDrake et al. (1950). ttHenle, W., et al. (I950).

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(I936), Proc. Soc. exper. Biol. Med., 35, 213.LAURELL, G. (1948), Acta. Med. Scand., 130, 299.LOE, F. (I938), J. Amer. med. Ass., III, I371.PAUL, J. R., and BUNNELL, W. W. (1932), Amer. 7. med. Sci.,

183, 90.

PETERSON, 0. L., HAM, T. H., and FINLAND, M. (I943),Science, 97, I67.

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Derm. Syph., 56, 846.

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