Plasmodium falciparum an antipodean case study dengue fever

Document Sample
Plasmodium falciparum an antipodean case study dengue fever Powered By Docstoc
					 ARTICLE                                                                                                     MALARIA DIAGNOSIS

Plasmodium falciparum:
an antipodean case study
 Plasmodium falciparum malaria was the subject of a case and poster
 presentation given by Jayachandran Radhakrishnan at an Australian
 Institute of Medical Scientists meeting in Bunbury, Western Australia.

A 47-year-old male presented to his GP               tests required at least a week for the results
complaining of intermittent fever, diarrhoea         to be returned, as they were performed in a
and vomiting. The GP noted that the patient          reference laboratory in Perth.
had travelled to the Ivory Coast in West Africa          However, a very low platelet count did
a month previously to attend a job interview.        give the GP reason to request further blood
In view of the patient’s condition, the GP           investigations. Meanwhile, on the following
decided to refer him to Kalgoorlie Regional          day, the patient was feeling extremely unwell
Hospital for further tests and a complete            and was admitted to the Kalgoorlie Regional
check. This short study illustrates the              Hospital.
importance of diagnostic methods in the early
detection of Plasmodium falciparum malaria           LABORATORY FINDINGS
and subsequent treatment outcomes.                   Initial full blood count on the samples
                                                     collected by the GP gave a low platelet count
PRELIMINARY INVESTIGATION                            (38 x 109/L) and a haemoglobin (Hb) value            Fig 1. A fresh blood test on Day 2 using a
Prior to referring the patient, the GP had asked     of 126 g/L (Table 1). The peripheral smear           malaria kit yielded a positive result for
him to undergo a series of blood investigations      examination undertaken in the laboratory to          Plasmodium falciparum.
including full blood picture, electrolytes, liver    detect the cause of the low platelet level failed
function tests (LFTs), C-reactive protein            to detect any platelet clumps. The CRP was              Fresh bloods were collected from the
(CRP), erythrocyte sedimentation rate (ESR),         elevated to 154 mg/L and LFTs showed an             patient and the laboratory performed a
and serology for influenza, dengue fever and         increase in alanine transaminase (ALT) or           malarial investigation that included a serology
atypical pneumonia.                                  γ-glutamyl transpeptidase (GGT) values.             test and also peripheral smear examination
    Initial laboratory results from these tests      However, the low platelet count and Hb gave         using thick and thin films. Noting the
yielded little information on which the GP           enough cause for concern for the clinician          patient’s history of diarrhoea and vomiting
could base a diagnosis. Most of the serology         to order a malaria investigation.                   and also his recent travel to Africa, a Widal
                                                                                                         test and blood culture were also requested to
 Table 1. Initial results on the bloods collected by the GP.                                             investigate the possibility of typhoid fever.
                                                                                                             Blood counts were performed on an
  Hb (g/L)                      RBC (x1012/L)              Platelets (x109/L)             CRP            LH500 analyser (Beckman Coulter), and
 (135–180)                        (4.5–5.5)                    (150–400)                 (<10)           thick and thin blood films were stained with
     126                            4.07                            38                    154            Leishman.

                                                                                                         DIAGNOSIS OF
 Table 2. Results over the four days following commencement of antimalarial treatment.                   P. FALCIPARUM MALARIA
                                                                                                         Fresh blood tests undertaken of Day 2 using
  Day                           Platelet count                 Infected RBCs         Absolute count      a malaria kit (BinaxNow, Inverness Medical)
                                   (x109/L)                          (%)                (x109/L)         (Fig 1) yielded a positive result for
     3                               51                             4.6                  150.6           P. falciparum. The thick (Fig 2a) and thin
     4                               89                             2.4                   78.3
                                                                                                         blood films (Figs 2b and 2c) showed a number
                                                                                                         of P. falciparum trophozoites and the level
     5                               119                           <0.5                   NA             of infected red cells was estimated at 7%.
     6                               211                           <0.5                   NA             Absolute count of the infected red cells was
                                                                                                         estimated at 261.1 x 109 cells/L. The blood

 2                THE BIOMEDICAL SCIENTIST                                                                                            OCTOBER 2009

 Fig 2. Thick (a) and thin (b and c) blood films showed a number of Plasmodium falciparum trophozoites.

cell counts correlated well with the clinical    patient was advised to visit his GP regularly      co-existing typhoid infection. Serology
picture. Platelet count was 45 x 109 cells/L     for blood tests to monitor the reduction in        investigations for dengue, influenza and
and the patient was anaemic (Hb 113 g/L).        infected red cells to an absolute count of zero.   Epstein-Barr virus were negative.
Neutrophils showed mild left shift and                                                                  Timely laboratory detection of the
moderate toxic granulation.                      OUT OF AFRICA                                      P. falciparum parasite improved the condition
                                                 The condition of the patient improved              of the patient; however, this case study also
TREATMENT AND FOLLOW-UP                          considerably after administration of the           highlights the need for travellers to take
The patient was started on intravenous (iv)      antimalarial drug. His platelet count              precautionary measures when visiting regions
antibiotics and was given an antimalarial        increased and the illness began to subside.        of the world in which malaria is endemic.
drug, which over a period of days decreased         It would seem apparent that he contracted
the percentage of infected red cells to          the malarial disease while on his visit to the
<0.5% and increased the platelet count to        Ivory Coast. The Widal and blood culture                           Jayachandran Radhakrishnan
211 x 109/L. On discharged from hospital, the    results were negative, which ruled out                             is a medical scientist working
                                                                                                                    at Kalgoorlie Regional
                                                                                                                    Hospital, Piccadilly Street,
     ‘In view of recent travel to Africa, a Widal test and blood culture                                            Kalgoorlie, Western Australia.

     were requested to investigate the possibility of typhoid fever’

                                Half-page Advertisement

 OCTOBER 2009                                                                                        THE BIOMEDICAL SCIENTIST                   3

Shared By: