Melioidosis in Imported NonHuman Primates

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					Journal      of Wildlife          Diseases        Vol.     6. October,              1970-Proceedinos                        Annual              Conference                            211




       Melioidosis                                         in Imported                                                   NonHuman
                                                              Primates

                                                    ARNOLD                      F. KAUFMANN                                W
                                                     AARON                  D.       ALEXANDER                             W
                                                               ANTON                M.     ALLEN                 W

                                                           RICHARD                    J. CRONIN                      l
                                                    LLOYD                  A. DILLINGHAM                                   Ill
                                                               JACK          D. DOUGLAS                           (I]
                                                     and         THOMAS                   D.     MOORE                     113



                                                                                Abstract

                     In 1969,         five      cases          of melioidosis                   in three           separate                  outbreaks                  were
            diagnosed            in nonhuman                   primates             in the        United                 States.         In the               first      out-
            break, two stump-tailed                         macaque                 monkeys   (Macaca    arcioides)                                        developed
            signs of the disease                         approximately                  6 months    after purchase.                                          A third
            animal,    a chimpanzee                   (Pan troglodytes),       probably     acquired                                                its infection
            from    one of these                    monkeys.    Two      other    unrelated      cases                                              involving                   a
            pig-tailed           monkey           (Macaca              nemestrina)                and           a rhesus               monkey                  (Macaca
            mulaua)          were      diagnosed.               These           monkeys           had           been        imported                3 years               and
            6 months,             respectively,                prior       to       the    recognized                     onset         of       their           disease.
           These         cases      represent            the     first      known           occurrences                    of spontaneous                             melio-
           idosis        in nonhuman               primates              in the United                 States.


                                                                           Introduction

    Melioidosis,    a serious     and frequently                                          inhabitant       of the                        soil  and water.   It can
fatal    zoonosis,   is endemic      to Southeast                                         readily      be isolated                          from   recently   culti-
Asia.    The causative     agent,   Pseudomonas                                           vated      areas   such                         as rice and oil palm
pseudomallei,      appears     to be a normal                                             fields.’




LB Epidemiology        Program,          National      Communicable                             Disease           Center,            HSMHA,                   PHS,         USDHEW,
            Atlanta.   Georgia       30333.
     Walter     Reed  Army      institute        of Research,       Walter                       Reed           Army         Medical             Center,              Department          of
            the Army,     Washington,             D.C.
(1] laboratory         Aids      Branch,        Division         of      Research         Services,         National               institutes            of     Health,          USPHS,
             Bethesda,        Maryland.
(4] Veterans       Administration            Hospital,          Albuquerque,              New         Mexico.
(I] Washington        Regional           Primate     Research               Center,        University             of       Washington,                Seattle,           Washington.
[4] Veterinary      Division,          6.571st   Aeromedical                 Research          Laboratory,                  Holloman               Air     Force          Base,      New
            Mexico.
212                  Journal       of   Wildlife      Diseases       Vol.       6, October,        1970-Proceedinqs                Annual      Conference

    Despite      the apparently         widespread        dis-                       apparent      for months      or years    after   the
tribution      of the organism,          clinical    human                           patient    has left an endemic         area.    It is
disease     associated     with it is not common;                                    this property     that concerns   us here.
however,       subclinical     infection       is. As many                               While        melioidosis            has      been       noted
as 15 percent          of certain      Southeast       Asian                         previously          in a variety              of nonhuman
population         groups    have      antibody       to Ps.                         primate         species,        those      cases      were      all
pseudomnallei.#{176}                                                                 diagnosed          in endemic               areas.57-101’        In
                                                                                      1969,     three      separate        occurrences         of the
   The       disease   in man               has   been referred
                                                                                     disease      were       noted      in the United           States
to as         the    “Vietnamese                 time     bomb”,                     in monkeys             that     had been         imported         at
because         it may      not             become     clinically                    least 6 months            earlier.


                                                                   First        Outbreak

     Case 1: Nineteen               stump-tailed             macaque                      The      abscess         wall       was       composed             of
monkeys          (Macaca          arcioides)            from        Thai-            necrotic         tissue,       masses          of fibrin           with
land were obtained                  on July 11, 1968, by                             diffusely          infiltrating            neutrophils,             and
an aeromedical                 research            laboratory             in         areas of hemorrhage.                     In the lungs,            there
New Mexico             from a dealer                in California.                   was marked              distention         of the alveoli              by
On July 25, one of them                             developed           an           a protein         - rich,       cell - free        edema         fluid.
abscess       on the left arm and axilla                              and            There       was also marked                  perivascular           and
pyoderma           with lymphadenitis                     of the left                peribronchiolar               edema.           The       liver      was
arm. He was treated                    with kanamycin                  but           remarkable           for the apparent                 dissociation
his      response          was         not        recorded.            On            of the hepatocytes                  in a fashion               similar
October         17, he was one of four monkeys                                       to that        classically          described            for lepto-
sent to a hospital                  in New             Mexico          for           spirosis.      There         was in addition               a focally
renal      clearance         studies.         There,         when        he          prominent,            chronic         inflammatory                infil-
was first taken            from his cage on Novem-                                   trate     in the portal              triads.       None        of the
ber      19, he was               noted          to be slightly                      other      organs        contained           significant         histo-
anemic.         A serum            sample           in December                      logic alterations.
was an abnormal                   light        green        color.       In
January         an indurated               lesion         was noted                      Case        2:        Because          of      the       potential
in the left axilla             with a 1 cm hard                      sub-            severity         of this            disease          in man,             an
cutaneous           mass.      The surface                was ulcer-                 epidemiologic               investigation           was initiated.
ated and exuding                a serous          fluid. Cultures                    A serologic             survey       was conducted                 of the
at that time were negative.                          Whether          this           4 remaining               stump-tail           monkeys             at the
was      thp same            lesion         as noted             in the              hospital, and all the stump-tail                             monkeys
previous July is not known.                              The lesion                  at the aeromedical                     research laboratory,
had      improved          by February                  14 without                   as well         as personnel               who          had contact
therapy,        but on February                   24 the animal                      with these monkeys.                    Five animals              -     two
was       anorectic         and        uninterested               in his             at the hospital               and three          at the research
surroundings.           On March               3, a 5 cm mass                        laboratory            -        had     titers       that      in man
was seen over the left clavicle,                              but this               would        be indicative            of infection            (titer      of
was apparently              unrelated            to the axillary                      1:80      by hemagglutination                        technique           or
lesion.       At this          point         the      animal          was             1:8 by complement                     fixation          technique).
killed.      At necropsy,             the mass was found                             Only one of the suspect                      animals         had been
to be a subcutaneous                        abscess.          Another                ill.The ill monkey                      -      a male          -       was
abscess       was found          in the retroperitoneum                              from        the same             shipment           as the index
extending          from       the femoral                triangle         to         case. In November                     1968 he was used in
the thorax.           Both       abscesses            contained             a        a study        in which            a permanent              subcutan-
milky        white       material           from          which        Ps.           eous catheter              was implanted                 in addition
pseudomallei           was isolated.              This isolate,           as         to an electrode                  device        in its skull.              In
well as those           in the following                  cases,      was            February           1969 a series              of abscesses             had
confirmed          at the National               Communicable                        developed           along        the subcutaneous                    route
Disease        Center,       and at the Walter                      Reed             of     the      catheter.           These         were         opened,
Army Institute            of Research.                                               drained, and                  cultured. Staphylococcus
Journal     of Wildlife      Diseases       Vol.   6, October,         1970-Proceedings               Annual       Conference                       213

aureus        and organisms             identified         as be-             four     contiguous             sinus       tracts       discharging
longing       to the klebsiella-aerobacter                  group             a yellow        exudate.          These        were 2 to 5 mm
were       recovered.         The abscesses             were     re-          in diameter              at their         orifice.        The     tracts
fractory       to treatment.        In May, Ps. pseudo-                       arose      from        areas      of poorly            encapsulated
tnallei      was isolated        from these. The other                        abscessation            in the subcutis.                 These      were
four      animals       (two from          an earlier         ship-           histologically            similar        to those of Case                 1.
ment       from      the same        company           that sold              The      only other             significant            lesions      were
the      index       case,      and    two        from       other            in the        liver.        The       liver        was      massively
shipments         of undetermined              origin)       never            enlarged         with         rounded           edges        and     had
showed        signs of overt illness.                                         many         small yellow absecesses varying
     An attempt           was made         to elicit disease                  from less than 1 mm to 2 cm in diameter
in the four clinically               normal         animals       by          distributed           randomly             in all lobes.             The
stressing        with steroids,        and then all five                      right lobe adhered                 to the abdominal                 wall.
animals         were     killed.     Only      the clinically                 The larger           liver abscesses                were typically
illanimal had any lesions.                                                    lined      with       yellow         friable          material        and
    At necropsy,        a yellow-green          exudate                       contained          a thick           yellow          exudate.        The
was oozing         from    around       the electrode                         smaller        ones         appeared            solid.       The      gall
device    implanted      in the skull        of the ill                       bladder         was        distended            with       20 ml of
monkey.      The exudate        originated       from      a                  thick,       yellow-green               pus.        Its wall         was
layer   of hemorrhagic         soft tissue     between                        replaced        by a thick layer of yellow                        tissue
the implant      and the calvarium.         The brain                         with      a rough            surface.         A band           of pale
was uninvolved. In the right                flank     just                    pink tissue extended                    across        the lumen          of
above    the wing of the ileum,            there were                         the gall bladder               (Figure         1).




#{163}    URE     1. Focal         areas    of hepatic           necrosis       and      mnassive       necrosis        of      the   gall  bladder
wall.      Note     the     band       of   proliferative            connective           tissue      extending              across     the   lumen
                                                            of   the   gall   bladder.
214                  Journal      of Wildlife        Diseases       Vol.       6, October,       1970-Proceedinas               Annual       Conference

     The wall of the gall bladder                           was thick-                 Case 3: In May 1969, a young                                 female
ened       and      fibrotic.            The        adjacent         liver         chimpanzee             (Pan troglodytes),                 which       also
parenchyma             had undergone                   degeneration                had an electrode                  device        implanted          in its
and fibrous              replacement.                 The      mucosal             skull,      showed          signs       of fever,            anorexia,
surface      of the gall bladder                     was no longer                 dehydration             and difficulty             in walking.            A
apparent        having          been replaced               by a layer             liver     biopsy          indicated           hepatitis,          which
of necrotic          tissue        infiltrated         with neutro-                correlated           with a high serum                      transami-
phils and macrophages.                                                             nase. It was treated                   with antibiotics               and
     The     earliest          liver        lesions        appear        as        supportive            therapy.         On June             7, several
neutrophilic            aggregations                usually       in the           abscesses          were       found        on its wrists              and
area of the triads. The later lesions                                have          hands.        A serum             sample          drawn        at that
a central        core of necrosis                    bounded         by a          time was light green                      and had a hemag-
loose     network            of connective                tissue      con-         glutination          titer of 1:2560              for Ps. pseudo-
taining       many            neutrophils               and      macro-            mallei.         The       animal          subsequently              died,
phages.        The         central            necrotic         zone       is       and Ps. pseudomallei                   was isolated.
filled    with a loose                  network           of fibrillar                 This        animal         was       imported            in April
material        with        intermeshed                macrophages                  1966 from             Africa,        a non-endemic                 area.
and      neutrophils.               These           larger       lesions           While        it had never               had        direct      contact
exert pressure             on the surrounding                     paren-           with monkeys,                the chimp            was housed             in
chyma       producing             a concentric              pattern      of        the same area as case 2 for a time. There
compression.             The         liver       appeared          to be           is a strong           probability           ihat the infection
reacting       to a general                toxic influence.             As         was      spread          from        the      monkey            to the
in case 1, there was a tendency                                  to dis-           chimp          during         clinical         examination               of
sociation         of       hepatocytes.                There         were          their respective            electrode          implants.
early thrombi             in some of the small veins.                                  After        this case occurred,                   all the ani-
     Although           the       organism              was      readily           mals in the aeromedical                          laboratory           col-
cultured       from all the lesions,                     it was diffi-             ony were examined                     bacteriologically               and
cult to identify                 them         with certainty             in        seriologically.             To date,             no new            cases
Brown       and Brenn stained                     sections.                        have been found.

                                                               Second            Outbreak

     On October              7, 1968,          a male          rhesus              cutaneous           abscess         was observed             on the
monkey           (Macaca           mulatta),         received         on           left dorsal           aspect        of the head,            directly
 October         1, at the National                 Institutes         of          over      the      site       of the         previous        fronto-
 Health       in a shipment               of 50 from            India,             parietal       craniotomy.             The abscess         contain-
 had soft stools,              for which          he was given                     ed thick pale yellow                    pus. A similar            sub-
tetracycline,           nitrofurazone,             and a com-                      cutaneous          abscess       was located           on the left
 mercially        made       oral feeding           mixture.         On            side of the chest, approximately                                1 cm
 December           2, he was issued to a psychol-                                 lateral      to the nipple,              and was connected
 ogy laboratory,              where        on December                18,          by a fistulous             tract to a larger           3 by 4 cm
 he underwent             a craniotomy             with excision                   abscess        in the left axilla,               apparently          in-
 of parts         of the cortical               sensory         areas.             volving        the axillary           lymph       nodes.. Intern-
Sensory         testing       was started            on January                    ally, multiple            0.5 to 1 cm abscesses                  were
 15, 1969, but the monkey                      proved        difficult             observed         in the liver, spleen,              pancreatico-
to test and train.                                                                 splenic       lymph         nodes,      and in the superior
     In late April            round        scabs      were       noted             gastric      nodes.        One of the livler abscesses
 at the surgical              scar;      by mid-May,               they            was contiguous                with the wall of the gall
appeared          raised       and were thought                  to be             bladder.         Two        1 cm subpleural              abscesses
underlain          by abscesses.            On May 19, the                         were found             on the dorsal              aspect      of the
lesions       were       distinctly         suppurative,            and            right     apical       lung lobe,           and lesions          were
 at that time similar                processes        were notic-                  found       also in several               mediastinal         lymph
ed on the skin                   of the chest              and      leg.           nodes.        The       pus in the internal                  lesions
Pseudomonas               pseudomallei             was isolated                    was thin and dull white or dull green.
from the lesions.                                                                      Histologically,               the      lesions       had       the
    The animal             was      killed on May 28. At                           appearance             of poorly            encapsulated           ab-
necropsy,          a 2 cm raised,               fluctuant,         sub-            scesses.
Journal         of Wildlife    Dseases     Vol.   6, October,           1970-Proceedings                   Annual         Conference

                                                            Third           Outbreak

    Melioidosis          was diagnosed             in October                      noted      on the medial                 aspect        of the upper
1969 in a 9-year-old                 female      pigtail      mon-                 right       forearm.              About          this       time,         Ps.
key (Macaca             nemesirina)           being       used     in              pseudomallei              was identified                in the origi-
behavioral        research      in Seattle.        The animal                      nal culture.
had been         semi-isolated           for 3 years,           but                     The       animal         died       on October                13. A
in May was caged                  near      the rest of the                        serum        sample        taken        several        hours       before
colony      while the floor was being repaired                                     death       showed          a hemagglutination                      (HA)
in    their        observation           compound.             The                 antibody           titer      for Ps. pseudomallei                         of
monkey         had      been      well      except        for un-                   1:2560.        A necropsy             revealed          1) complete
explained        lameness          in the right leg and                            resolution           of the abscess                 over the right
mild anemia            in August          1969, for which                          frontal         bone       and eyelid,               2) a marked
she received           iron parenterally.                On Sep-                   accumulation               of purulent               material          over
tember       18, she had extensor                 paralysis        of              fascial        planes         on the proximal                      medial
the right         leg compatible              with       a radial                   aspect        of the           right        arm,        3)      a large
nerve      injury,      mild      swelling       of the right                      unilocular              abscess           beneath            the      right
eyelid,     and generalized             lethargy,         and she                  mammary                gland         which         extended           in a
was placed          in isolation.                                                  proximal-lateral                  direction          to the axilla,
                                                                                    with     no gross             anatomic            connection             be-
    Within     several     days, a large fluctuant
                                                                                    tween        the infections                on the right                arm
swelling    developed        over the frontal            bone,
                                                                                    and     the       mammary                gland,         and      4)      the
extending      over the orbital         crest to involve
                                                                                    right     lower         lobe       of the lung contained
the right       palpebrum.         The      swelling       was
                                                                                    two 2 x 2 cm firm nodules                                which       were
excised    and 10 ml of a thick,                 grey-white
                                                                                    granulomatous               in consistency.
fluid was drained.          The abscess          was flush-                             In the serologic                    examination               of the
ed and packed           with a furacin           seton,     and                     remaining            20 animals              in the behavioral
sodium       ampicillin       therapy        was started.                            group,      seven had HA titers to Ps. pseudo-
Lincomycin          was then        used     after      a pre-                      mallei         ranging           from         1:80        to 1:2560.
liminary      culture      of the abscess             demon-                        These       animals         were all killed                and exam-
strated     a coagulase            positive        staphylo-                         ined no lesions                 compatible             with melioi-
coccus      and       a hemolytic           streptococcus                            dosis were present                  nor was the causative
sensitive    to lincomycin.                                                          agent isolated.           Serology           and fecal cultures
    On October                3, three      fistulous        tracts,                 of all other            animals          in the colony                like-
discharging    a              purulent       material,          were                 wise failed to uncover                    any further           cases.

                                                            Serologic                  Survey

      When initiating   the epidemiologic      study                                   To set a baseline,      serum     samples     were
 of the first outbreak,       we did not know                                          obtained from      a variety      of macaques
 what     importance     to attach      to the low                                     imported from     endemic     areas    as well as
 titers   in many     of the contact       animals.                                    some born in this country.        All the serum


                              TABLE        1. Melioidosis           in non-human                     primates         -     1969.

 Case               Species                       Natural       Habitat                    Date     Imported                  Onset      Illness*

         1         Macaca      arctoides          S. E. Asia*           *#{149}            July    1968                       Jan.     1969
         2         Macaca    arctoides            S. E. Asia*           *                  July 1968                          Feb.      1969
         3***      Pan troglodytes                Africa                                   April 1966                         May       1969
         4         Macaca    mulatla              India* *                                 Oct. 1968                          April       1969
         S         Macaca    nemestrina           S. E. Asia**                             1966                               Aug.       1969
         *When      signs of illness     first recognized
     *   *Endemjc        area of melioidosis
 *   *   *Infection      probably    acquired     from case                       2.
216                   Journal        of Wildlife          Diseases             Vol.           6, October,                 1970-Proceedings                     Annual            Conference

samples      were checked         by a hemagglutin-                                                  mallei   were present       in 239 (95.6 percent)
ation (HA) technique.’                                                                               of the imported        animals.      Eight     had HA
    Serum      samples     came       from     284 mon-                                              titers of 1:80, and three had 1: 160 titers
keys -        250 imported           animals      and      34                                         (Table   2). All of the 34 monkeys                born
born in the United           States.     The imported                                                in the United        States     had titers       of less
group included 135 Macaca                    nemestrina,                                             than 1:80 (Table 4). The distribution                  of
93 Macaca        arctoides    and 22 Macaca             irus.                                        titers  had no apparent            correlation      with
The     animals      born   in this country            were                                          year of importation          (Table      3) or age in
all M. nemestrina.                                                                                   the case of animals born in the United
    Hemagglutination          titersfor Ps. pseudo-                                                  States  (Table   4).


       TABLE            2. Hemagglutination                            titers         for          Pseudomonas                           pseudomallei                  in   clinically
                                               normal                imported                  macaque                    monkeys.

                                                                   Hemagglutination                              Titer
                                                                                                                                                                                      Total
Species                         <1:20                         1:20                            1:40                    1:80                      1: 160       >1:        160         Animals

M.     nemestrina                60*                          41                            29                        4                           1                -                     135
                            (44.4)                 (30.3)                      (21.4)                         (2.9)                       (0.7)
M.     arctoides                 42                           33                              15                      3                     -                      -                      93
                            (45.2)             (35.5)                          (16.1)                        (3.2)
M.irus                           12                            7                          -                           1                           2                -                      22
                            (54.5)             (31.8)                                                         (4.5)                       (9.1)
Total                           114                81                              44                           8                            3                     -                     250
                            (45.6)             (32.4)                          (17.6)                        (3.2)                        (1.2)
*Number             of animals           (precent             of species                  group)



       TABLE           3.     Hemagglutination                        titers          for          Pseudomonas                           pseudomallei              in       clinically
                            normal      imported                   macaques                   with      known                importation                 dates.

                                                               Hemagglutination                                 Titer
Year                                                                                                                                                                          Total

Imported               <1:20                       1:20                        1:40                     1:80                       1:160              >:160                 Animals

1969                        36*                    28                         13                            4                         2                  -                       83
                       (43.4)                (33.7)                      (15.7)                         (4.8)                      (2.4)

1968                        28                        10                      10                            1                        -                   -                       49
                       (57.1)                (20.4)                      (20.4)                         (2.1)

1967                        11                        12                              9                  -                           -                   -                       32
                       (34.4)                (37.5)                      (28.1)
1966                      28                     21                           9                            1                         1                   -                       60
                       (46.6)                (35.0)                      (15.0)                         (1.7)                      (1.7)
1965                            5                      5                              2                  -                           -                   -                       12
                       (41.7)                (41.7)                      (16.7)
1964                                                      1                     -                        -                           -                   -                          1
                                             (100)
Total                    108                     77                         43                            6                          3                   -                    237
                       (45.6)                (32.5)                      (18.1)                        (2.5)                       (1.3)
*Number             of animals          (percent              of group              imported                  that         year)
    Journal      of Wildlife            Diseases            Vol.   6, October,               1970-Proceedings                    Annual          Conference                            217

        The     HA       titers      were      determined         for                              titers of 1: 16. In none    of the contacts
    four     of the          culture-positive           monkeys.                                   were lesions   compatible  with melioidosis
    These     ranged       from      1:320 to 1:10,240. In                                         seen;  nor   was the organism     recovered
    two of the outbreaks, 24 contact                       animals                                  (Table 5).
    were examined               at necropsy         for evidence                                        Considering        the foregoing          data and the
    of melioidosis.             Four     of this group had                                         serious      nature      of the disease           in man,       a
    been      stressed          with      steroids      prior       to                             conservative          interpretation           of the      HA
    necropsy in an attempt to induce acute                                                         titers was adopted.              It was felt that titers
    disease.     Nine       of the 24 contact             animals                                  of 1:40 or less were                 negative,        1:80    to
    had HA          #{149}titers  ranging from            1:80 to                                   1:160     were suspect,          and 1:320        or greater
     1:2560 -        five had 1:80, one 1:160,                   one                               highly     suspicious       of active infection.
     1:320,    on#{231}1:1280 and one 1:2560. The
                                                                                                       Because      of the     limited     volume     of
    remainder         had titers         of less than          1:80.                               monkey      sera available    and some technical
    In addition,        two animals             with HA titers                                     problems,      a comparable       study of comple-
    of 1:20 or less had complement                        fixation                                 ment fixation      serology    was not possible.



         TABLE                   4. Hemagglutination                     titers for Pseudomonas                                  pseudomallei               in c linically
                                     normal      Macaca                 nemestrina born in the                                 United         States.

                                                                    Hemagglutination                          Titer
Age                                                                                                                                                                   Total
Years                                           <1:20                                 1:20                         1:40                 1:80      or more            Animals

3 orless                                           13*                              1                          -                                  -                            14
                                                (92.9)                             (7.1)
4ormore                                            13                                 4                          1                                                             18
                                                (72.2)                           (22.2)                        (5.6)
Unspecified                                             -                         -                           2           -                       -                                2
                                                                                                        (100.0)

Total                                               26                               5                            3                               -                            34
                                                (76.5)                           (14.7)                        (8.8)
*Number                    of animals           (percent            of group)




    TABLE                   5.     Hemagglutination                     titers        for Pseudomonas                   pseudomallei        in non-human
primates               with        culture      confirmed               cases          or in contact                animals    subsequently       necropsied.

Category               -                No.     Animals                HA Titer                                Comment                                             Culture
Case                                                1                  1: 10,240                               Case            1, outbreak              1                 +
Case                                                1                  1:320                                   Case            2, outbreak              1                 +
Case                                                1                  1:2560                                  Case            3, outbreak              1                 +
Case                                                1                  1:2560                                  Outbreak                 3                                 +
Contact                                             2**                1:80-1:160                              Outbreak                  1*
Contact                                             7                  1:80-1:2560                             Outbreak                 3                             -


Contact                                         13                     <1:80                                   Outbreak                 3                             -


     *Stressed             with      steroids        in an attempt                    to induce        acute          disease.
*    *Two         additional              contact            animals           in outbreak               1 had                complement                fixation          titers       of
       1:16      for       Pseudomonas                  pseudomallei                  but     HA     titers        of 1:20              or less.
 218                  Journal       of   Wfldlife       Diseases       Vol.    6, October,          1970-Proceedings                 Annual        Conference


                                                        Disease         in Human              Contacts

    In the three    outbreaks,   all personnel                                        examined,       ten     had    HA   titers   ranging
having    contact  with nonhuman       primates                                       from     1:80 to 1:320;        the remainder       had
were serologically      screened  for evidence                                        titers    of 1:40      or less. No evidence          of
of infection. Of 115 people serologically                                             active human        infection   was found.


                                                                         Discussion

     The lesions observed                    in the current                           observed.         In four of the cases,                  the ani-
cases are consistent with those described                                             mals     had been           out of an endemic                  area
previously in nonhuman                     primates as well                           for 6 months           to 3 years.          In one case, in
as in man.”7’#{176}”          The lesions are similar                                 a chimpanzee,           the animal          had never been
in all involved            organs.        There         is usually
                                                                                      in an endemic            area and probably                 acquir-
a white to yellow exudate which                                   may
                                                                                     ed its infection              in the laboratory.                 The
have     the “earthy”             odor      associated           with
                                                                                     pathogenesis           of the spontaneous                   disease
the organism.             About         a central          core       of
                                                                                      is not known.           The apparent             long incuba-
this purulent exudate, there is frequently
a zone of fibrin               and early           proliferation                     tion     periods        probably          reflect       an early
of fibrous          connective           tissue       containing                     acute or subclinical               infection        with conse-
many        neutrophils,             macrophages,                  and               quent      persistence         of a nidus of infection,
areas     of hemorrhage.                The tissue            of the                 possibly       as a focal osteomyelitis.                  Then       in
involved organ peripheral to this outer                                               times of stress the persistent                   nidus breaks
zone is often necrotic,                     infiltrated          with                down        producing          an acute        manifestation.
neutrophils, and contains areas of hemor-                                            Definite proof             of such a sequence,                 how-
rhage.     The lesions          are not granulomatous                                ever, has not been obtained.
though       they      were      described           as such          in                  In three of the five cases, first signs of
the earlier       literature.’         While        Ps. pseudo-                      the disease           appeared          at the        site of a
mallei       is easily           cultivated            from         the              surgical        procedure.         In two, this was at
lesions,     the organism             is often difficult              to             the site of implanted                foreign       objects,      and
demonstrate           in histologic preparations.’                                   in one         at the site of an old surgical
We have found it easy to demonstrate
                                                                                     wound.         For this reason,               one should            be
the organism            in sections           cut from            rou-
                                                                                     alert      to the        possibility          of melioidosis
tinely processed,            paraffin-imbedded                 tissue
                                                                                     when       dealing      with surgical           wound         infec-
blocks      using      fluorescent           antibody           tech-
                                                                                     tions in monkeys              from endemic             areas.
niques.
    An unusual       clinical        feature       observed                              If an isolate    from an animal             is suspect-
in cases 1 and 3 during             the first outbreak                               ed of being        Ps. pseudomallei,              it should
was the light green serum               which probably                               be handled with caution.               Laboratory           in-
reflects   acute  liver damage.               This is sup-                           fections    have occurred          and can be quite
ported   by the high serum                   transaminase                            serious.’    All suspect        isolates       should        be
levels in the chimpanzee.                                                            submitted       to a laboratory         experienced           in
    The  striking    feature       of this disease          is                       handling      the organism         for identification
the long incubation          period       which      may be                          or confirmation.


                                                                    Acknowledgments
       The   authors       would       like     to thank           the    many        laboratory           personnel        who       contributed           to this
report,  especially       Robert      Weaver,          M.D.,       Ph.D.,      and     Wallis       Jones,       Ph.D.,     Laboratory           Division, and
James    C. Feeley,        Epidemiology              Program,          NCDC.        Scrum        for the serologic              survey       was     contributed
by the following           organizations:             Delta      Regional        Primate          Research          Center,       Covington,          Louisiana;
Holloman      Air Force        Base,      New      Mexico;         Lovelace        Foundation,          Albuquerque,             New      Mexico;        National
Center    for Primate        Biology,        Davis,        California;        Oregon        Regional          Primate       Research         Center,       Beaver-
ton, Oregon;        Washington          Regional         Primate        Research         Center,      Seattle,       Washington;           Yerkes        Regional
Primate      Research       Center,         Atlanta,        Georgia;         and      Naval        Aerospace            Medical        Center,        Pensacola,
Florida.
Journal      of   Wildlife      Diseases     Vol.    6, October,   1970-Proceedings           Annual      Conference                   219


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