Periodicity of Brugia malayi Appearance in Blood of Domestic Thai Cats in Surat Thani Province

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Usa Lek-Uthai
Kosum Chansiri
Supit Yodmek



This study aimed to determine the periodicity of appearance in the blood circulation of a catsample. Sixty-five domestic Thai cats from Tha Chana District, Surat Thani Province wererecruited and their blood was collected, stained with Giemsa and examined microscopically for theparasite. Ten cats (15.4%) were infected with Brugia spp, but the remainder were not. The average ageof the infected cats was 51-2 years. All isolates of Brugia spp from infected cats were identified as B.malayi, using PCR technique with primer Bm-1/Bm-2 (specific to B. malayi) and using DNA (at 10ng/50 ml) extract from feline WBC and W. bancrofti as negative control. The sensitivity of B. malayiDNA detection was 0.0001 ng, and the amplified DNA was shown to represent the same specific typeas infects man. The appearance of B. malayi was monitored every two hours over 24 hours’ observation.A modified harmonic equation showed the highest parasitemia peak at 00.54 hr. All five domesticcats showed the appearance of microfilariae at almost all observed intervals with the maximal peaksat nighttime, the highest peaks expressed being 59.3, 74.0, 618.0, 210.3 and 32.0 microfilariae at20.00, 18.00, 24.00, 06.00 and 06.00 hr, respectively, These findings indicated the nocturnalsubperiodic type of microfilariae presented in the cat sample. They also indicated that the mode oftransmission was transient and restricted, considerably at nighttime, and would be helpful forepidemiological study of the parasite reservoir.

Keywords: periodicity, Brugia malayi, domestic Thai cat

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