Table 1. Comparison of the phylodynamic patterns of MSM, IDU and non-B heterosexual epidemics.
| Frequency of infections in cluster groups (% cases) | Cluster interval | ||||||
|---|---|---|---|---|---|---|---|
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| Risk group | Location | Inclusion criteria | Unique | Small 2–10 | Large +10 | Median (months) | <6 months (% cases) |
| MSM | Montreal | Acute/PHIa | 30 | 42 | 28 | 15 | 27 |
| MSM | Amsterdam | Recent < 18 months | 43 | 57 | 0 | 17 | 25 |
| MSM | UK/London | PHI/Chronic | 60 | 28 | 12 | 22/14 | 16/25 |
| MSM | France | PHI (Cohort) | 83 | 17 | 0 | 15 | 30 |
| MSM | Denmark | PHI/Chronic | 51 | 18 | 31 | ||
| MSM | Belgium | Recent <1 year | 53 | 28 | 19 | ||
| MSM | Switzerland | Acute/PHI/Recent | 64 | 0 | 36 | ||
| Mixed | North Carolina | PHI/Chronic | 66 | 29 | 4 | ||
| IDU/HET | Switzerland | Acute/PHI/Recent | 41 | 0 | 63 | ||
| IDU/HET | Montreal | Acute/PHI/Recent | 30 | 45 | 25 | ||
| HET | Denmark | PHI/Chronic | 85 | 9 | 6 | ||
| Non-B | Montreal | PHI/Chronic | 74 | 24 | 2 | ||
| Non-B | UK | PHI/Chronic | 75 | 20 | 5 | ||
| Non-B | Switzerland | Acute/PHI/Recent | 78 | 22 | 0 | ||
| Non-B | Belgium | Recent (<1 year) | 87 | 12 | 0 | ||
Data were extracted from studies performed in Quebec [27,29], Netherlands [94,182], United Kingdom [31,90,93], France [105], Denmark [101], Belgium [111], Switzerland [86,103] and North Carolina [106] to elaborate the relative role of nonclustered (unique), small clustered (2–10) and large clustered (10+) networks in different settings. The median cluster intervals and the percentage of linked infections occurring within 6-month intervals substantiate the relative role of early infection. HET, heterosexual; PHI, primary HIV infection.
a
The Montreal study included drug-naive and treated chronic populations to establish cluster size but excluded these samples from analysis of cluster intervals.