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THE ZOONOSES AND PAEDIATRICSBy R. I. MACKAY, M.B., M.R.C.P.(Lond.), D.C.H.

Consultant Paediatrician to Hope Hospital, Salford

The World Health Organization has adoptedand popularized the term ' zoonoses '1 which isapplied to those diseases which are transmissiblefrom animals to man. Altogether a total of some8o diseases are included among the zoonoses, aword used almost universally in the plural. Mostof these diseases have been known for many yearsand in somne parts of the world they constitute amajor social and economic problem. In depressedpopulations the morbidity and mortality amongstchildren is high and chronic infection and infesta-tion are responsible in part for reduced vigour andcapacity for work in the young adult. In theUnited Kingdom many of the well-recognizeddiseases of earlier times have been controlledalmost to the point of extinction, and because ofthis the subject has received little attention fromBritish writers in recent years. Even less interesthas been shown by paediatricians in the zoonoses,perhaps because they are not an important causeof infant mortality or even a common cause ofserious illness. Nevertheless there is evidencethat certain of the zoonoses occur with sufficientfrequency in the British Isles to be included in thedifferential diagnosis of many febrile conditionswhich might otherwise remain unexplained.Although the zoonoses include all diseases trans-

missible from animals to man, the mode of life inthe United Kingdom is such that the source ofinfection for the majority of persons is likely to bea domestic pet kept in the house though in agricul-tural communities other domesticated animals maybe responsible. Cats, dogs and caged birds havebeen most frequently incriminated in previousstudies but mice, rabbits, fowl and pigeons allfeature in their turn. Almost any farm animalmay be the source of infection though cattle,sheep, pigs and poultry have been responsible onmost occasions.

Hu112 tabulates about 20 diseases known to havebeen carried by dogs and cats, some of them byeither animal and approximately half of theminfestations. In spite of this knowledge theseanimals continue to live in close proximity tohumans, frequently under unhygienic conditions

-to the disadvantage of both parties. Matheson3estimated in I944 that the cat population of Britishcities was approximately Io to i5 per cent. of thehuman population and that a city the size of Cardiffwould have supported about 30,000 cats. House-holds in the poorer and older parts of cities aremore likely to keep cats than the modern housingestates; 75 per cent. of households in the dockarea kept a cat in I944 as compared with 34 percent. on a housing estate. Apart from regulationsagainst p)ets, the greater incidence of rodentinfestation in the poorer quarters was held toaccount for the difference. In addition to house-hold pets the number of stray cats in British citiesis equivalent to about 3 per cent. of the totalhuman population and about 6,ooo cats aredestroyed per annum by various agencies in eachof the large industrial cities. Matheson4 alsoestimated the dog population of Great Britain in.I953 to be equivalent to 6 to 7 per cent. of theadult population and that there were 3,860,ooodogs in the country in 1950. The numbers ofother domestic pets is not estimated but a rapidsurvey of households in Salford in I955 gave someindication of their popularity. During a routineschool medical inspection I28 consecutive childrenwere questioned about pets in the home with thefollowing result:

Cats .. .. .. ..74Dogs .. .. .. ..33Fish .. .. .. .. 25Caged Birds .. .. .. .. 15Pigeons .. .. .. .. 7Rabbits .. .. .. .. 3

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Ninety-one out of I28 households had domesticpets and 36 of these households had two or morepets. The children attended a school in a denselypopulated industrial area near factories and dock-land and lived in terraced houses of the back toback type. A more direct experience, though lesswell documented, is that of visiting children in theirhouses as a physician. One often finds the patient

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January I956 MACKAY: The Zoonoses and Paediatrics 17febrile and with a respiratory infection nursed in aliving room with a budgerigar for company orwith dog, cat or pet mouse within reach.The total range of the zoonoses is too extensive

for review in a short article and the works of Hu112and Rivers5 should be consulted for completeaccounts. We are concerned here with a selectionof the zoonoses, those which have been describedin Great Britain and, where possible, those whichhave involved children. It will be seen that thepaediatric zoonoses is a neglected topic in thiscountry but one which merits the practical con-sideration of every family practitioner.Bacterial Infections

Tuberculosis. It must be remembered that non-respiratory tuberculosis of animal origin is apreventable disease and that although greatadvances have been made in Great Britain in recentyears the disease has not been eradicated. In 1953,2,26o cases of non-respiratory tuberculosis werenotified as occurring in children under I5 years ofage,6 approximately one-third of the total. SinceI938 the notifications of this disease have beenreduced from 6,853 in this age group, though lesseffectively in other age groups. This improve-ment is due to the policies of heat treatment ofmilk and to the attested herds schemes introducedin i935 and 1950. By September I952, 37-5 percent. of cattle in England and Wales were inattested herds.7 At the same time 62.5 per cent.of cattle were not.

Cases of cervical adenitis and bone tuberculosisstill occur in children who have been allowed todrink raw milk and parents are generally not awareof the risk. In recent years an outbreak of tubercu-losis occurred in a village school due to raw milkbeing served to the children at school. All Educa-tion Authorities now serve only heat-treated milkin the School Milk Scheme. Only rarely does ahuman case infect milk after pasteurization. Withcorrect handling this should not occur. It maynot be generally known that Swiss workers haverecently shown that the goat is not immune totuberculosis and can produce infected milk.

Salmonellosis. In view of the greatly increasedprevalence of salmonella infections in the last 15years it is relevant to consider the role of animalvectors. Many of the strains of these organismsrecently recognized have been introduced fromabroad in food and by human carriers. At thesame time salmonellosis is enzootic in the animalpopulation in this country, particularly amongrodents. Food stores invaded and contaminatedby rats and mice have been the source of explosiveoutbreaks in institutions and in the population ingeneral. Salmonellosis is enzootic among cats anddogs also, the infection probably acquired from

rodents and contaminated food, but possibly insome instances from humans. A survey of 500dogs and 500 cats carried out in I949 showed anincidence of I per cent. in the former and 1.4 percent. in the latter of excretion of pathogens.8 Inthe United States a similar survey showed anincidence among dogs to be as high as 27.6 percent. Salmonellosis also affects the bird popula-tion and in the survey quoted above 2.25 per cent.of a sample of pigeons excreted salmonellae.

It is clear that domestic pets must be included inthe general epidemiological study of an outbreakof salmonellosis or in the single case within anapparently healthy family. Moreover the petsmust be regarded as equally susceptible in an out-break and require the same barrier technique whenhandled or fed.Dogs and cats excrete helminths and giardia

lamblia in even higher proportions but this prob-lem will not be discussed further in this article.

Leptospirosis. This infection is usually con-sidered in differential diagnosis when there is aknown occupational risk. Among children thediagnosis is more likely to be missed unless afulminating infection forces the clinician to recog-nize the textbook disease. Broom writing in I9519analyses the results of investigations for lepto-spirosis among cases of aseptic meningitis. Among642 cases of aseptic meningitis, L. icterohaemor-rhagiae was involved in 17 and L. canicola ineight. In frank leptospirosis 36 children wereaffected with Weil's disease in a group of 36Ipatients whose sera were sent to the leptospirareference laboratory, and among 64 cases ofcanicola fever I5 were children under I5 years ofage though only one child was under five years ofage. It would appear that these infections aremilder in children than in adults and Broomexpressed surprise that the infection was onlyrarely recognized in children. According to thefigures he quotes, no child had died of lepto-spirosis. Weil's disease is mainly an occupationalhazard, but children are infected when theircuriosity or natural environment brings them incontact with infected rodents, rodent excreta orcontaminated water. A case is reported in a childwho bathed in stagnant water. In contrast,canicola fever is mainly a domestic hazard and inmost cases follows contact with a sick dog. ' Theyellows' is not uncommon among dogs andBroom1° in another paper estimated that up to 40oper cent. of dogs in Glasgow in I946 had beeninfected with L. canicola, and in a survey of 403dogs of different breeds from several areas inGreat Britain he found 27 per cent. with evidenceof leptospiral infection. The incidence was lowerin agricultural areas than in towns. Broom givesa warning about the care needed in the nursing of

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POSTGRADUATE MEDICAL JOURNAL January 1956sick dogs in the home, pointing out that youngpuppies can be affected and that excretion ofleptospira in the urine can continue for manymonths after the dog's illness.

Classical Weil's disease with septicaemic mani-festations, jaundice and nephritis is not likely topass unrecognized in children, but canicola feveris probably more frequent than we realize. In theform of aseptic meningitis it may be recognized inhospitals sufficiently alert to pursue the diagnosisin a benign and self-limited illness. Moreoverleptospirosis may occur as an illness resembling'influenza' with headache, meningism, conjunc-tivitis and muscle pains. It may not be sufficientlydefinite to rouse suspicions of poliomyelitis orsimilar infections and may never be accuratelydiagnosed. Jaundice and skin manifestations occurin less than 20 per cent. of patients with canicolafever though albuminuria can be found in 43 percent. (Broom). During epidemic seasons 'infec-tive hepatitis' is accepted as a diagnosis forchildren with jaundice and fever. Usually a satis-factory contact history can be obtained. When nocontact history is found the matter is rarelypursued unless the course of the illness gives rise toanxiety.

Apart from serological and bacteriological testswhich are the only accurate methods of diagnosis,Broom1° states that the erythrocyte sedimentationrate is raised in the early stages of leptospirosis asdistinct from other forms of ' aseptic' meningitisand that a normal E.S.R. in such a case excludesleptospirosis.

Brucellosis. This infection is not common inthis country but the diagnosis is not infrequentlymade on slender evidence. Official figures report96 cases of brucellosis in England and Wales ini95311 and show an incidence in the rural districtsmore than ten times that of the county boroughs.It is usually said that children are resistant toinfection, but this is denied by Professor Renoux12who asserts that children will become infected ifopportunity occurs-' there is no bovine focus ofB. melitensis without human cases.' There iseven one instance reported of a baby of five monthsinfected by excretion of organisms into his mother'smilk. Human brucellosis (abortus) is usually con-tracted from infected milk, eating unpasteurizedcottage cheese and by agricultural contamination.Infections by inoculation of the skin or mucosae orinhalation are more significant in B. melitensisinfection.There is nothing unusual about the clinical

picture in childhood; an acute febrile illnessoccurs or a more prolonged ' pyrexia of unknownorigin' characterized by exacerbations and re-missions develops. Diagnosis is confirmed byblood culture or agglutination reactions and treat-

ment with oxy- or chlor-tetracycline is recom-mended. Renoux advises the combination of oneof these antibiotics with streptomycin. Vaccinesare used and on occasion cortisone is used withantibiotics.

Tularaemia. There do not appear to be anycase reports of tularaemia in children in the BritishIsles but it is a recognized hazard of laboratoryworkers and rabbit fanciers. It is interesting tonote a case report from Poland in which Gelberdescribes eight cases in children of 4 to 14 yearswho played with the carcase of a hare. All thechildren involved in the game were ill with sorethroat and adenopathy. The diagnosis was con-firmed by agglutination reactions and the childrensuccessfully treated with chloramphenicol andstreptomycin. It may be of interest that the reportmentions a yellow coloration of the palms of thehands and the palate, known as Piotrowka's sign,as being helpful in diagnosis.l3Viral Infections

Psittacosis. Ornithosis. Sufficient work has nowbeen done on this disease in man for us to be ableto assert that association with psittacine birds,pigeons and fowls increases the risk of the infec-tion. Rivers5 states that ' a history of associationwith birds always suggests a diagnosis of psittacosisin patients with pneumonitis.' In spite ofnumerous case reports only very few children havebeen proved to have the disease. Meyer andEddie14 found no child aged one to nine years ini i i patients with psittacosis in whom the age wasrecorded on the request to the laboratory, and theymention a German survey in which two childrenwere found to have psittacosis out of a group ofI6o patients. Strobel'5 describes the disease intwo children in a family infection and Ellenbogenand Millerl6 mention a I6-year-old youth with thedisease.

It has been established that the infection in birdsis characterized by a viraemia with localization ofthe virus in spleen, liver and kidneys and thatinfected birds may excrete virus for a long time,often becoming carriers. The feathers and cagedust are contaminated and inhalation of dust is theusual mode of infection for man. Psittacosis inman is usually a benign illness, but Meyer andEddie record a mortality of 9.3 per cent. in theirseries. The disease usually appears as an influenza-like fever with severe headache, sore throat andphotophobia with a dry cough. Untreated, thefever may continue into a second week but mayfall at the end of seven days. Epistaxis is seen in25 per cent. but cough may be absent even whenthere is an extensive pulmonary consolidation. Onoccasions a typhoid-like illness develops withabdominal symptoms, nausea and diarrhoea. The

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January I956 MACKAY: The Zoonoses and Paediatrics 19

spleen may be enlarged and ' rose spots ' appear onthe body. It is characteristic that few physicalsigns can be detected in the chest in the presenceof extensive consolidation. Diagnosis is confirmedby inoculation of blood or sputum into mice in theacute stages or by the demonstration of a risingtitre of specific complement fixing antibodiesduring the illness. Although it is generallyaccepted that the infection responds to penicillin,chlortetracycline is also recommended.

In 95 per cent. of the cases recorded by Meyerand Eddie exposure to birds was recorded, and in35 per cent. infection was due to pigeons.

Ducks, canaries, chickens and grouse have beenproved to be the source of infection. However it isnot necessary for a bird to appear ill to be anexcretor of psittacosis virus and quarantine regula-tions only exclude the obviously diseased birds. Itis impossible to escape the conclusion that a pro-portion of acute febrile and respiratory illness inchildhood may be due to psittacosis and that thechances are increased in households with cagedbirds as pets. So far there is no recorded study ofthe disease among children in this country, thoughatypical pneumonia of virus origin is not rare."7

Canine distemper and feline pneumonia. As longago as 1928 Bryan showed that canine distempercould be transmitted from man to animals and thatchildren with respiratory infection could transmitan illness to puppies. This work was repeated in193i by Nicolle. Adams'8 in a series of articlesfrom 1941 to 1953 has attempted to prove that thevirus of distemper can produce a respiratory ill-ness in children and adults and that encephaliticsymptoms may appear as in puppies. He statesthat infants and small children may be affected, theseverity of the disease decreasing with increasingage. Mortality is high among premature infants.He supports this with evidence drawn fromepidemiological studies and from an identity ofpathology in animals and man. Human immuneserum and human gamma globulin was shown toexert a protective influence in experimental infec-tion comparable with hyperimmune distemperantiserum and ferret immune serum.There is also a condition known as ' housedog

disease 'which is regarded as the common coldtransmitted from humans to dogs.

Baker'9 produced evidence that the virus offeline pneumonia could be transmitted from cats tohumans and in one instance from a child to a cat.It is suggested that this virus is antigenically re-lated to the psittacosis-lymphogranuloma group.Benign inoculation lymphoreticulosis (cat scratch

fever). The more imposing title suggested byMollaret for this disease is perhaps more appro-priate than the more popular ' cat scratch fever.'The coup de grace has been administered to this

term by the discovery that the disease can betransmitted by other means than by the scratch ofa cat.

This adenopathy was recognized by Lee Foshayin 1932 during a study of tularaemia, but littlewas done to publicize the discovery until Foshaydiscussed the topic with Debr6 and a commonexperience was revealed. Case reports began toappear in French and American literature in 1950.There were over Ioo cases in the literature by I951.Although individual clinicians have recognizedcases in children in the British Isles the Englishliterature refers only to adults.23 There is no doubtthat this disease is quite common among childrenin this country but is usually unrecognized becauseit is benign in outcome. With the reduction in thenumbers of tuberculous and simple septic glands inrecent years, diagnosis should have become easier.The classical picture is that of suppuration in a

lymph node or nodes associated with a variabledegree of toxaemia. When the complete historyis known a cat scratch or cat bite may be recalledthough other modes of inoculation have been re-corded. There is usually a mild inflammatoryreaction at the site of injury a few days after itoccurs. Swelling of regional lymph nodes com-mences a minimum of four days and a maximumof 28 days after inoculation and may progressthrough all stages of suppuration to sinus forma-tion with slow healing. Sometimes the swollenglands may form a mass 3 to 4 in. in diameter, butoften they are smaller. As would be expected, theadenitis is usually unilateral but bilateral cervicaladenopathy has been recorded and there is someevidence that respiratory infection may occur. Atthe height of the adenitis a variable degree offever and toxaemia may develop with headacheand sometimes a rash. A papule may develop atthe site of inoculation at this stage. Greer andKeefer reported an eruption resembling erythemanodosum2' in this disease. The differential diag-nosis includes septic and tuberculous adenitis,tularaemia, lymphogranuloma and reticuloses in-cluding malignant tumours and leukaemia. Thereis no leucocytosis, pus and glands are sterile onculture and serological investigation is usuallynegative with occasional positive reaction withantigen prepared for complement fixation tests forlymphogranuloma. The only specific diagnostictest is a skin test resembling a Mantoux reactionperformed with antigen prepared from provedcases of the disease. (It is interesting that Danielsand MacMurray20 obtained positive skin tests withantigen prepared from cases on both sides of theAtlantic.)

Treatment of the adenopathy is entirely em-pirical with surgical intervention when indicated.If a sinus forms it may take many weeks to heal,

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20 POSTGRADUATE MEDICAL JOURNAL January 1956but the scar is inconspicuous. Antibiotics have noeffect on the inflammation, though tetracyclineshave been regarded as helpful.Although there is an undoubted association with

cats, there is no evidence of any disease in theanimals responsible for inoculation. It wouldappear to be an infection passively transferred,almost certainly -a virus infection according toMollaret's study, but a virus as yet unidentifiedthough possibly related to the psittacosis-lympho-granuloma group.Daeschner et al.22 describe I2 cases among

children aged from I6 months to Io years collectedover a period of i8 months. They describealternative clinical pictures which are convincingin their context. Apart from local and respiratoryinfection mentioned above, cough and transientpulmonary infiltration, conjunctivitis with cervicaladenitis and a transient severe encephalitis (re-ported by Stevens) are included. We return withthis to the relationship between feline pneumoniaand psittacosis. It is certain that these relatedphenomena form a disease complex which isgradually being elucidated and which is widespreadamong cat lovers if not in the rest of the population.

Lymphocytic choriomeningitis. In this context itis worth while to consider lymphocytic chorio-meningitis shown by Duncan and co-workers in195 24 to be due in certain circumstances to in-fection acquired from mice infesting houses or aneighbourhood in which cases occur. In an out-break in Manchester, Duncan25 examined theepidemiology of 24 cases of whom two werechildren under io years and two aged io to I9years. In addition a boy of seven years was knownto have had meningism and fever before his motherdeveloped the typical disease. In this particulardistrict, in contrast to other districts of Man-chester investigated, infection of the mousepopulation with the virus of L.C.M. was demon-strated. Smith and Kinsella26 in the same yearinvestigated an epidemic in Co. Durham but madeno observations on the number of children involvedor on the source, though evidence of infection wasfound in two Alsatian dogs in a farming community.

Apart from the typical acute meningitis syn-drome, Duncan reports proved cases in whom theillness resembled influenza with headache, vomit-ing, cough, low-grade fever and with photophobiain one-third of these cases. It is of very practicalimportance that he found the sugar content of thecerebrospinal fluid to be reduced in a number ofcases, contrary to orthodox opinion, giving rise toa mistaken early diagnosis of tuberculousmeningitis.

It is of great interest to the paediatrician tonote that Komrower27 has recently describedlymphocytic choriomeningitis in a newborn infant

in whom transplacental infection is believed tohave occurred. The mother lived in the neigh-bourhood investigated by Duncan after the earlierepidemic.

Epizootic stomatitis (foot and mouth disease).This condition is briefly described in River's text-book as a vesicular stomatitis with fever andsalivation. There is a vesicular eruption on thepalms of the hands and soles of the feet whichspreads to the interdigital clefts. These lesionsulcerate before recovery. This disease may befamiliar to country practitioners but it was in-teresting to encounter a report from Poland(Czarnowski et al.)28 of three children living on afarm who developed the disease from infectedcattle, the diagnosis being checked by complementfixation tests. Ulceration is described in thesechildren as occurring round the edge of the fingernails. No treatment is recommended.

Rickiettsial InfectionsQ fever. The only rickiettsial infection of any

practical importance in Great Britain is Q fever,caused by rickiettsia burneti (also known asCoxiella burneti). Until Stoker reported threecases in I949 the disease was thought to be a featureof tropical or subtropical countries. Epidemics of' atypical pneumonia' in troops in the Mediter-ranean area during the second World War wereshown to be due to Q fever. The increasinginterest in the disease is shown by the experienceof the Virus Reference Laboratory29 of the PublicHealth Laboratory Service. Out of 700 specimensreferred from cases of acute respiratory disease,3 per cent. showed a significant titre of antibodyfor R. burneti. In ' atypical pneumonia' 5 percent. of patients showed significant titres of anti-body. Stoker30 estimated that i6 per cent. of allpneumonia and unexplained fever in Kent was dueto Q fever and that the incidence in the townsmight be as high as 25 per cent. Although childrenhave been involved in small outbreaks of Q fever(Stoker30) and have been studied in epidemiologicalsurveys, it appears that no proved cases of Q feverin children have been recorded in Great Britain todate. Suspicious febrile illnesses and unrelatedincrease of antibody titre have been observed inchildren.There is now a great deal of literature on the

epidemiology of Q fever (Babudieri31, MacCal-lum32, Marmion et al.33) and it appears that themode of spread may vary from country to country.At first shown to be carried by ticks in early out-breaks, milk contamination was held responsiblein California; in Italy and, more recently, inGreat Britain cattle and sheep have been shown tobe excretors. The rickiettsiae are excreted in theplacenta and uterine discharges of the parturient

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January I956 MACKAY: The Zoonoses and Paediatrics 2I

animal and may be found in cow's' milk. It issuggested that infected placentae may be eaten byfarm dogs and that the dogs become excretors. Ithas been shown that intestinal passage of theorganism is possible in the dog without illnessbeing noticed in the anilpal. In fact no detectableillness occurs in other animals known to beexcretors or to have significant antibody titres.The great resistance of the rickiettsia to drying andthe small size make it possible for dust-borneinfection to be responsible for epidemic infection.Babudieri describes an epidemic of this type in avillage near Ancona. Curiously enough milk-borne organisms do not seem to cause illness tothe same extent as dust-borne infection, theCalifornian experience being somewhat unique inthe epidemiology. Evidence of infection byfomites has been collected by Marmion37 andother workers and has explained epidemics inwhich there was no obvious occupational risk.Humans very rarely pass the infection to others butthis has been recorded in closed hospital com-munities.A sufficient number of cases have been des-

cribed in England to be certain that the disease isnot rare (MacCallum, Marmion33, Stoker"4 andothers in various papers) and the present localiza-tion in Kent is certainly related to the diligenceof the investigators. Slavin35 has shown a muchmore widespread infection of cattle. Significantantibody titre was demonstrated in 2.1 per cent.of cattle and in a nation-wide survey he found 6.9per cent. of infected farms in England, 2.0 percent. in Wales and o.8 per cent. in Scotland. Heat-treatment of milk destroys rickiettsiae though theorganism can survive several weeks in raw milkproducts.

Infection of the human placenta has beendemonstrated and rickiettsiae isolated six monthsafter a clinical infection with Q fever treated withchloramphenicol and tetracyclines. The fate ofthe baby in this case is not clear. Rickiettsiae canbe excreted in human milk but the infant seemsto have an acquired immunity. There is of coursea risk of infection in banked human milk if in-efficiently pasteurized.

In adults the disease takes the form of a suddenfever climbing to a swinging pyrexia over severaldays and falling by lysis. The incubation period.seems to be I6 to I8 days and there is greatprostration with nocturnal delirium, muscle pains,backache and headache. The headache is aggra-vated by coughing, but there is usually nomeningism.There is an irritating cough but characteristic-

ally no evidence of upper respiratory infection.Small areas of crepitations or bronchial breathingmay be found in the chest, and inspection of a

chest radiograph may reveal rounded peripheralopacities in the lung fields or segmental collapse(Harman36). Joint pains and swellings, orchitisand encephalitis have been reported, gastro-intestinal symptoms are rare, the spleen andlymph glands are usually not enlarged.The disease carries a very low mortality rate

and treatment with chloramphenicol or tetra-cyclines has been shown to be effective.

Diagnosis is confirmed by isolation of rickiettsiaefrom blood or sputum in the acute stages, and bycomplement fixation and agglutination titres com-pared between the acute and convalescent stages.An intradermal test can be used in confirmationbut is fallacious as an isolated diagnostic technique.

Agricultural communities are clearly at risk andafter them families who live near cattle markets,abattoirs and railway sidings and those whosehouses are situated along streets along which herdsare driven from docks or railway stations to theabattoirs. It is probable that infection is to beexpected only after long dry periods in summer,at least as far as town populations are concerned.

It would seem that there is every opportunityfor widespread infection with R. burneti in theseislands and no reason why children should escape.Perhaps the disease is milder in children but afterconsideration of the history of the recognition ofQ fever it is clear that only an enthusiastic in-vestigator in touch with a virus laboratory isrequired to demonstrate cases among children.

Protozoal InfectionsToxoplasmosis. Although the existence of the

organism Toxoplasma gondii has been recognized'for almost half a century, and although humaninfection was described over 30 years ago, only inthe last Io years has the extent of human infectionbeen appreciated. There is no doubt that countriesin which a high incidence has been recorded arethose in which enthusiastic investigators have beenworking.38 Nevertheless there is now sufficientevidence to assert that infection with this parasiteis quite common in the British Isles and thatclinical syndromes have been recognized in infantsand young children.

Fisher 39 reported a series of ioo inpatients atthe Hospital for Sick Children, Great OrmondStreet, who were tested with toxoplasma antigenas a skin test. Three children showing a positiveskin test also showed positive serological reactionsand one child among the negative reactors hadpositive serological reactions. A more extensivesurvey of 639 mental defective children showed 35with positive reactions. A review of these studiesshowed a rising incidence of positive tests in theseselected groups from less than I per cent. underfour years of age to 17.5 per cent. in children over

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22 POSTGRADUATE MEDICAL JOURNAL January I956

15 years old. This series is in agreement withreports from other countries in the rising incidenceof infection through the years. Macdonald40 onthe other hand found positive serological tests inonly 13 out of 350 healthy adults but positive re-sults were obtained in Io out of 12 children withchorioretinitis and cerebral calcification. Positiveresults were obtained in four children among 88with other congenital anomalies (ages not recorded).Toxoplasma infection has been demonstrated in

many animals and birds. In some countries(Switzerland, Sweden) reservoirs of infection inthe animal population have been defined. Althoughthere is little doubt that the organism is the sameas that found in human cases, it has not yet beenproved that infection is definitely transmitted fromanimals to man nor the route by which suchinfection is passed. In the United States twogroups of investigators have inferred that domesticdogs have infected the families with whom theylived. Cole et al.41 studied I2 volunteer families(involving 37 persons) who owned a total of 28dogs admitted to the Ohio State UniversityVeterinary Clinic with evidence of toxoplasmosis.No disease was recognized in 35 of these personsand clinical examination was negative. Toxo-plasmin skin tests were done and io personsshowed a positive reaction, nine of whom also hadsignificant serological reactions. Doubtful resultswere found in a further seven persons. Threechildren under 14 years of age were included. Oneof these had congenital toxoplasmosis with stronglypositive serological reactions and the child'smother also had serological evidence of infection.One three-year-old child had a weakly positivetest with a negative skin test and one I2-year-oldchild had a positive skin test with negative serology.Both were symptom free. Prior et al.42 producedfurther evidence of human infection in associationwith animal infection. Asymptomatic para-sitaemia was discovered in a young woman whokept dogs known to be suffering from toxoplas-mosis. A second woman developed toxoplasmaencephalitis, her dog being infected previously.A third case described in this series was a 3-year-old child who died of toxoplasmosis with pertussisbut no association with pets is recorded.

Infection in man has been recognized as threedistinct syndromes at different ages with the addedpossibility of asymptomatic infection, which hasits greatest significance in women of child-bearingage.

Congenital toxoplasmosis is the most frequentlydescribed syndrome but it is also the easiest torecognize and may attract more attention becauseof the extensive damage to the foetus. Theaffected infant may be born with a hydrocephalusor may develop microcephaly or hydrocephalus

shortly after birth. There is usually microphthal-mia with enophthalmia. Convulsions may occurand as the months go by mental retardation be-comes more obvious. If one adds to this thefinding of chorioretinitis and the demonstration ofintracerebral calcificationon a skull radiograph,the classical clinical syndrome is revealed.

Acquired disease in infancy is known to producea fatal meningoencephalitis, the diagnosis beingmade primarily by the pathologist. In adults andolder children a rickiettsial type of infection hasbeen described which has many of the features ofinfectious mononucleosis. Persistent fever ofvariable degree, adenopathy, splenomegaly and amaculopapular rash have been shown to be due totoxoplasmosis. The rash develops on the trunkand limbs but spares the scalp, palms and soles(Sabin38) and may resemble typhus or RockyMountain spotted fever. Pneumonitis oftenoccurs, sometimes after the rash has appeared.The syndrome may resemble glandular fever veryclosely, and Cathie43 found in sera from 2o childrenand young adults evidence of toxoplasma infectionin seven, the patients all having clinical glandularfever with a negative Paul Bunnell reaction.

Skipper et al.44 described two cases of this type,one of them a boy of i 5, the diagnosis being madeon the basis of serological tests. At the same timethey point out that toxoplasmosis is a rare cause ofglandular enlargement since the two cases were theonlyv examples among 86 patients.

Diagnosis is established by a positive skin re-action to toxoplasma antigen and by serologicaltests. The dye test becomes positive early in thedisease and the complement fixation test later,though titres fall rapidly. Complete proof isobtained only by isolation of the protozoon byanimal inoculation.Many antiprotozoal agents have been used in

attempted treatment of toxoplasmosis with littlesuccess. Sulphadimidine, sulphones and pyrime-thamine have been used on animals but no clearguidance is available for the treatment of humancases recognized in the acute stage. There is littlepoint in treating chronic infections unless infectionis discovered in a pregnant woman.

Parasitic Diseases. Hu112 lists i8 parasitic infestations transmittedby dogs and 13 transmitted by cats, many of thediseases attributable to either. In this review it isintended to mention only hydatid disease becauseit has aroused paediatric interest in this country inrecent years. Practitioners in South Wales will bemore familiar with the disease than others since itis five times as common in Wales than in Englandand 35 times as common as in Scotland. In arecent communication Gray45 reviewed 25 cases o f

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January 1956 MACKAY: The Zoonoses and Paediatrics 23

Disease Skin Test Identification of Organism Serological Tests

Tuberculosis Mantoux Pus, sputum, urine, etc.Brucellosis (doubtful value) Blood culture, urine, faeces. Agglutination titres.Salmonellosis Blood culture, urine, faeces. Agglutination titres.Leptospirosis - Blood culture, urine, C.S.F. Agglutination titres. (E.S.R.)Tularaemia Foshay Blood culture. Agglutination titre.Psittacosis - Blood, sputum. Rising antibody titre.Cat Scratch Fever Specific - Low titre lymphogranuloma agglutination

(with negative Frei test).DistemperL.C.M. - C.S.F. Complement fixation test. Rising antibody

titre.Epizootic Stomatitis - - Complement fixation test.Q Fever (doubtful value) Blood, sputum. Complement fixation. Agglutination titre.Toxoplasmosis Specific C.S.F. Biopsy. Complement fixation test. Rising dye test

titres.Hydatid Disease Casoni Biopsy. Sputum. Complement fixation test.

The above tests are performed by the laboratories of the Public Health Laboratory Service (except tests forepizootic stomatitis) fro-n wh3vn antigen for skin tests can be obtained.

Specimens for identification of organism should, in general, be sent as early as-possible in the disease.At least two specimens are necessary for precise serological diagnosis, the first early in the disease and the second

four to six weeks later.Special packing is necessary for specimens for virus identification if they must be sent by post.

hydatid disease discovered in children in SouthWales. Hepatic cysts were most frequent andpulmonary cysts second in importance. Among 70cases at a hospital for chest diseases I2 werechildren with pulmonary cysts. Hepatomegaly inan endemic area strongly suggests a diagnosis ofhydatid disease. Cerebral cysts and mesentericcysts were also encountered but they may occurin any organ.

In what has become a classic review of hydatiddisease in the British Isles, Wolfe46 in i943 des-cribed a series of 34 cases of whom seven wereunder 20 years old and the youngest case was achild of two-and-a-half years. Since thesilent development of cysts may take many years hesuggested that many infections were acquired inchildhood or early adult life. Barrett and Thomas47in a review of pulmonary hydatid disease includednine children under io years of age among 71cases collected in 14 years. Dogs are implicated asthe most important vector in these papers. Barrettand Thomas state that infection is not uncommonin towns if persons keep greyhounds or coursingdogs, but that certain districts or even villagesmay become important centres of infection.

Diagnosis is confirmed by the Casoni test andby complement fixation tests. The skin test re-mains positive for years after the removal of thecysts but the complement fixation titre fallsrapidly unless active hydatid tissue remains.The peculiar geographical incidence of hydatid

disease is probably due to the unusually highincidence of infestation in sheep from Wales. Atthe Cardiff abattoir I to 2 per cent. of sheep have

hydatid cysts which presumably implies heavyinfection of grazing land. Although infection fromsheep is possible, human infection usually comesfrom handling dogs whose coats are contaminatedwith ova. The dogs are infected from grazingland, from feeding on carcases of dead sheep andfrom offal from animals slaughtered as diseased.There does not appear to be any reason why SouthWales should be more heavily afflicted with hydatiddisease than any other area except for the heaviercontamination of grazing land which has so far notbeen eradicated.

SummaryIt is often said that paediatrics and veterinary

medicine have much in common. This may betrue as far as practice with the younger age groupsis concerned but it may be that the connectionbetween the two subjects is more important.Without over-emphasising the frequency of infec-tions transmitted from animals to children it isclear that there is a wide field of investigation forboth the laboratory worker and for the familypractitioner. It must be remembered thatchildren are the usual source of infection for otherchildren but there are many occasions when thisexplanation may not be valid. Domestic pets mustbe included in the consideration of domesticepidemiology.

Consideration of preventive measures involvesthe proper care of small children and of domesticpets in a common environment. The prematurebaby and the infant under one year need particularprotection. Nor should the protection of animals be

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POSTGRADUATE MEDICAL JOURNAL January 1956

forgotten. Many thousands of animals and birdsare kept in unsatisfactory and unhygienic con-ditions. The usual practice of accommodating petsin the house leaves much to be desired.

During the preparation of this paper the PaediatricClinics of North America5a published a more extensivereview of ' Unusual Infections in Childhood' to whichpractitioners are referred for more detailed accounts ofthe above diseases and of others common in the UnitedStates. There is also a more comprehensive list ofreferences in each section though mainly concerningAmerican literature.

I would like to record my appreciation of the workdone by Health Visitors of the City of Salford and theirSuperintendent, Miss B. Langton, in the short surveyof domestic pets described above.

REFERENCESGeneral:I. 'Advances in the Control of Zoonoses' (I953), WHO/FAO

Seminar, Geneva.2. HULL, T. G. (I955) 'Diseases Transmitted from Animals to

Man,' 4th edn., Thomas.3. MATHESON, C. (i944), .7. Anim. Ecol., 13, 130.4. MATHESON, C. (I953), .7 Roy. San. Inst., 73, I43.5. RIVERS, T. (I954), 'Viral and Rickettsial Infections of Man,'

2nd edn., Lippincot.sa. ' Pediatric Clinics of North America' (February I955).Tuberculosis:6. ' On the State of the Public Health' (I953), H.M.S.O.7. WHO/FAO SEMINAR, Annexe 2, p. 25.Salmonellosis:8. THOMAS, O. M. (I954), 'The Public Health Aspect of

Domestic Animals. Dissertation for D.P.H.,' Universityof Manchester.

Leptospirosis:9. BROOM, J. C. (X95x), Brit. med. _., ii, 689.

Io. BROOM, J. C., and MAcINTYRE, A. B. (1948), Vet. Rec.,60, 487.

Brucellosis:Ix. 'On the State of the Public Health' (I953), H.M.S.O., p. 97,

p. 246.12. RENOUX, G. E., WHO/FAO Seminar, p. 6i.Tularaemia:13. GELBER, J. (1953): Pediatr. Pol., 28/7, 699Psittacosis, Ornithosis:14. MEYER, K. F., and EDDIE, B. (x947), J.A.M.A., x33, 822.

15. STROBEL, W. (1954), Deutsch. Med. Wschr., 79/5, 176.I6. ELLENBOGEN, B. K., and MILLER, C. M. (1952), Brit.

med. .., ii, I89.17. 'Virus Pneumonia in Children' (1952), Annotation, Lancet

i, 803.Canine Distemper:I8. ADAMS, J. M. (1953), Pediatrics, 3I, i5.Feline Pneumonia:19. BAKER, J. A. (1942), Science, 96, 475.Cat Scratch Fever:20. DANIELS, W. B., and MAcMURRAY, F. G. (I95I), Arch.

int. Med., 33, 736.21. GREER, W. E. R., and KEEFER, C. F. (I95I), New Eng.

J. Med., 244, S45.22. DAESCHNER, C. W., SALMON, G. W., and HEYS, F. M.

(1953), Y. Pediatr."43, 371.23. ANNOTATIONS (1952), Lancet, i, pp. 320, 646, 673, 975.Lymphotic Choriomeningitis:24. DUNCAN, P. R., et al. (I9Si), Lancet, i, 956.25. DUNCAN, P. R. (1952), 'Thesis for M.D.,' University of

Manchester.26. SMITH, R. C. F., and KINSELLA, J. J. (I95I), Lancet, i, 882.27. KOMROWER, G., et al. (I955), Lancet, i, 697.Epizootic Stomatitis:28. CZARNOWSKI, A., et al. (1953), Pediatr. Pol., 28/8, 858.Q Fever:29. ANNOTATION (i950), Lancet, ii, 630.30. STOKER, M. G. P. (I953), Ibid., 1, 137.3I. BABUDIERI, B. (I953), WHO/FAO Seminar, p. I57.32. KAPLAN, M. M., and HULSE, E. C. (I953), bid., 175.33. MARMION, B. P., et al. (I594), Lancet, i, 1288.34. STOKER, B. P. (1954), Trans. Roy. Soc. Trop. Med. Hyg.,

48, 19I.35. SLAVIN, G. (I952), Vet. Rec., 64, 743.36. HARMAN, J. B. (I952), Postgrad. Med. J., 28, 481.37. MARMION, B. P. (r954), Trans. Roy. Soc. Trop. Med. Hyg.

48, 197.Toxoplasmosis:38. SABIN, A. B. (I942), Advances in Pediatrics, i, I.39. FISHER, O. D. (I95I), Lancet, i, 904.40. MACDONALD, A. (I950), Ibid., ii, 560.41. COLE, G. R., et al. (I953), Arch. int. Med., 92, 308.42. PRIOR, J. A., et al. (9953), Ibid., 92, 314.43. CATHIE, I. A. B. (1954), Lancet, i, 813.44. SKIPPER, E., et al. (I954), Ibid., i, 287.Hydatid Disease:45. GRAY, O. P. (I953), Arch. Dis. Child., 28, 243.46. WOLFE, H. R. I. (I943), Lancet, 1, 795.47. BARRETT, N. R., and THOMAS, D. (1952), Brit. J. Surg.,

40, 222.

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