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Malaria

 

Excerpt from UptoDate.com:

 

'There are no pathognomonic clinical signs or symptoms for diagnosis of malaria [12,13]. The most predictive findings of malaria are

  • fever without localizing symptoms,

  • enlarged spleen,

  • platelet count less than 150 x 10(9)/L and

  • bilirubin greater than 1.3 mg/dL;

this was illustrated in a study of 1962 travelers returning with fever [14].

The presence of skin rash, skin ulcer, and eosinophilia was predictive of non-malarial disease.

 

Blood counts are often abnormal but are not specific. In a series of Canadian travelers, patients with malaria presented with anemia in 41 percent of cases [15]. White blood cell counts were elevated above 9.8 x 10(9)/L in 3 percent of patients but were less than 5.0 x 10(9)/L in 48 percent [15]. Platelets were low in 83 percent of Plasmodium vivax-infected patients (mean 102 x 10(9)/L), and in 62 percent of P. falciparum-infected patients (mean 137 x 10(9)/L).

 

Detection of parasites on Giemsa-stained blood smears by light microscopy is the gold standard for diagnosis of malaria.

 

Given the cyclic nature of malaria parasitemia, smears should be evaluated every 6 to 12 hours for 48 hours before the diagnosis of malaria is ruled out [21]. The first smear is positive in 95 percent of cases.'

 

Local Microbiology advice suggests in low risk cases a single negative malarial film and negative malarial antigen is adequate to exclude malaria.