Comparison of microscopy and PCR for the detection of human Plasmodium species and Plasmodium knowlesi in southern Myanmar

Objectives To determine the distribution of Plasmodium (P) species including Plasmodium knowlesi and to compare the specificity and sensitivity of microscopy with nested PCR in malaria diagnosis. Methods The study was conducted in Kawthaung, southern Myanmar. Ninety clinically suspected malaria patients were screened for malaria by Giemsa stained microscopy and confirmed by nested PCR. Results Among the participants, 57 (63.3%) were positive and 33 (36.7%) were negative by microscopy. Of positive samples, 39 (68.4%) were Plasmodium falciparum, 17 (29.8%) Plasmodium vivax and 1 (1.8%) Plasmodium malariae, whereas 59-amplified by PCR were 40 (67.8%), 18 (30.5%) and 1 (1.7%) respectively. PCR amplified 2 microscopy negative samples. Two samples of P. falciparum detected by microscopy were amplified as P. vivax and vice versa. All samples were negative for Plasmodium ovale, P. knowlesi and mixed infections. Microscopy had a very good measure of agreement (κ = 0.95) compared to nested PCR. Sensitivity and specificity of microscopy for diagnosis of P. falciparum were 92.5% (95% CI: 79.6–98.4) and 96.0% (95% CI: 86.3–99.5) respectively, whereas for P. vivax were 83.3% (95% CI: 58.6–96.4) and 97.2% (95% CI: 90.3–99.7). Conclusions P. knowlesi was not detected by both microscopy and PCR. Giemsa stained microscopy can still be applied as primary method for malaria diagnosis and is considered as gold standard. As to the lower sensitivity of microscopy for vivax malaria, those with previous history of malaria and relapse cases should be diagnosed by RDT or PCR combined with microscopy. Inaccuracy of species diagnosis highlighted the requirement of training and refresher courses for microscopists.

Pneumocystis carinii infection among human immunodeficiency virus (HIV) infected Myanmar patients.

A total of 60 HIV infected patients complaining of dry cough for at least two weeks and attending the Out-patient Department of the Specialist Hospital, Waibargi, were screened for Pneumocystis carinii. Induced sputum samples were examined with Giemsa and Gomori silver methenamine stains. P. carinii were detected in 18 patients (30%) with silver stain and 13 patients (21.7%) with Giemsa stain. The sensitivity and specificity of the Giemsa stain were 72.2% and 95.2%, respectively. The range of CD4 counts in P. carinii-positive patients was found to be 0-562/microl, and the mean CD4 count was 132.3/microl. Out of 18 P. carinii-positive cases, CD4 counts of 15 cases (83.3%) were <200/microl and those of 3 cases were >200/microl. Clinically, P. carinii-positive cases were associated with fever in 55.5%, with tightness of the chest in 38.9%, and with cyanosis and tightness of the chest in 11.1%. Co-infection with tuberculosis was found in 16.7%. Anti-pneumocystic prophylaxis is recommended for those patients with a CD4 count <200/microl. Giemsa staining could be used as an alternative diagnostic method for detecting P. carinii. This study documented the existing prevalence of P. carinii among HIV-infected Myanmar patients.

Humoral immune response to falciparum malaria during pregnany

Humoral immune respone against Plasmodium Falciparum was studied ontwo hundred and thirty seven pregnant and non pregnant women in Tha-hton township during premonsoon season of 1998. Slide positivity rate among pregnant women was 7.3

(10/137), fifty percent of which were primigravide. Eighty percent of infection occured druing second trimester. Antimalarial antibiodies were determined by both Indirect Fluorescent Antibody Test (IFAT) and Enzyme Linked Immunosorbent Assay (ELISA). IFAT seropositivity rate was 63.33

(n=33) in primigravidae and 83.63

(n=11) in non pregnant healthy women. In the convalescent sera, the rates were 77.14

(n=7) and 87.33

(n=15) respectively. These IFAT results were also comparable with those of ELISA. Lower seropositivity rate and mean antibodytitre were observed in pregnant women compared with non-pregnants. These findings inply that there is suppression of antimalarial immunity druing pregnancy