Table 1 Based on a classification system published in January 2007, Blastocystis isolates from humans, animals, and birds are identified as Blastocystis sp. subtypes 1 to 9, as determined by analysis of SSU rRNA sequences [41].
From: Oh my aching gut: irritable bowel syndrome, Blastocystis, and asymptomatic infection
Sub-type # | Yoshikawa subtype # (used in some earlier studies)[41] | % of Blastocystis isolates in population belonging to this subtype from study in China adjusted for co-infections[43] | Results from animal study from Egypt[48] | Characteristics in human infection | ||
|---|---|---|---|---|---|---|
Blastocystis sp. subtype 3 | (3) | 66% | Illness | Cows, Pigs | Associated with most chronic symptomatic infections [44, 47, 51] | + |
Blastocystis sp. subtype 1 | (1) | 28% | Illness Death | Cows, Pigs, Chickens, Monkeys | Associated with many chronic symptomatic infections [44, 47, 51] | ++ |
Blastocystis sp. subtype 2 | (5) | 5% | Not done | Dogs, Monkeys | Usually asymptomatic [50] or co-infection in symptomatic patients [44] | +++ |
Blastocystis sp. subtype 4 | (7) | 0.5% | Not done | Rodents | Rare in one population study [43], but was more common in a study of symptomatic patients at clinic [52] | ++ |
Blastocystis sp. subtype 6 | (4) | 0.5% | Illness | Birds | Rare in one population study [43], but found in a study of symptomatic patients at a clinic [48] | Unknown |
Blastocystis sp. subtype 5 | (6) | 0% | Not done | Pigs | Rare in one population study [43] | Unknown |
Blastocystis sp. subtype 7 | (2) | 0% | No Illness | Birds | Rare in one population study [43], but found in a study of asymptomatic individuals [48] | Unknown |