Prevalence of Parasitic Contamination of Cockroaches Collected from Fresh Markets in Chachoengsao Province, Thailand.

Cockroaches are the greatest potential mechanical vector of various pathogenic microorganisms. This study aimed to determine the prevalence and species type of human pathogenic parasite infestations on the external body surface of the cockroaches. A total of 450 cockroaches collected from three fresh markets were identified in three species belonging to Periplaneta americana, Periplaneta brunnea and Periplaneta australasiae. Helminth and protozoan species were identified by using a direct wet smear technique and modified acid-fast staining technique. The overall prevalence rate of parasitic infestation on the external body surface of cockroaches was 46.4% (209/450). The number of cockroaches infested with protozoa was 44.7% (99/209) and helminths was 44.0% (92/209), while 8.6% (18/209) were infested by both protozoan and helminth parasites. A total of 272 parasite specimens belonging to 16 species were found: ten species of protozoan were identified as Cryptosporidium spp. (15.4%), Entamoeba histolytica/E. dispar (8.5%), Cyclospora spp. (7.0%), Blastocystis hominis (6.6%), Cystoisospora belli (6.6%), Endolimax nana (4.0%), Entamoeba coli (2.2%), Chilomastix mesnili (1.5%), Balantidium coli (1.1%) and Iodamoeba butschlii (1.1%); six species of helminths included Toxocara spp. (8.5%), Trichuris trichiura (6.3%), Ascaris lumbricoides (5.9%), Taenia spp. (5.1%), Strongyloides stercoralis (4.4%), and hookworm (2.2%). Unidentified species of the helminths were isolated, namely nematode larva (9.9%) and helminth eggs (3.7%). Our results show that the cockroaches collected from fresh markets are potential mechanical vectors of several protozoan and helminth species.