Guidelines for second generation HIV surveillance - World Health ...

Low-level epidemic: brief explanatory notes
• Size estimation data: Rapid situation assessments can be used to estimate the size of populations with
high-risk behaviours in an area in a cost-efficient manner. More specific and precise data on size through
detailed mapping should be conducted in areas where the largest numbers of persons with high-risk
behaviours are found. Where resources are limited, updating size estimates should be prioritized in
areas with the largest epidemic potential, usually where the largest numbers of key populations at
higher risk are found.
• HIV case reporting: Case reporting data are useful for triggering further investigation into an area when
sudden spikes or unusually large numbers of cases are reported. It is important to understand the
underlying pattern of testing, diagnostic capability and reporting by different facilities to interpret these
data appropriately.
• STI case reporting: Case reporting for STIs can be based on either syndromic (diagnosis based on
symptoms) or laboratory diagnosis. Syndromic case reporting should focus on urethral discharge in
men. Urethral discharge is highly suggestive of recent unprotected sexual intercourse. Where available,
etiological case reporting should focus on primary and secondary syphilis and gonorrhoea, since these
are acute conditions also suggestive of unprotected sexual intercourse.
Evaluating a National Surveillance System
Surveillance data on vaginal discharge should be interpreted with caution since non-STIs such as bacterial
vaginosis or candidiasis present in a manner similar to that of STIs. Although genital ulcers can be a
manifestation of acute infection with syphilis or chancroid, increasingly, herpes simplex virus (HSV) has
become the major cause of genital ulcer disease in many countries (especially in countries with a high HIV
prevalence).
• Facility- or community-based sentinel surveillance for HIV and STIs for key populations at higher risk:
This type of surveillance is only possible when large numbers of beneficiaries regularly access services
at a community site.
• Sites where outreach staff accompany or actively recruit key populations at higher risk to the service
will not provide a systematic facility-based sample that produces reliable prevalence data.
• Small sites will not provide an adequate sample size to meet the requirements of a high-quality
sentinel surveillance system.
• Biobehavioural surveys: When resources are limited, only a small number of surveys should be planned.
Aim for areas where the largest numbers of key populations at higher risk are identified, such as capital
cities. Do this type of surveillance activity only after other higher priority surveillance activities have
been put in place. At a minimum, test routinely for syphilis. Syphilis rates among key populations at
higher risk may provide an early warning of HIV transmission. Nuclei acid amplification tests (NAAT) for
gonorrhoea and chlamydial infection may be incorporated into special studies.
• ANC syphilis surveillance: Increases in the prevalence of syphilis among ANC attendees can be
used to identify women at increased risk for HIV, and may provide an early warning of changes in
HIV transmission in the general population. Transition to PMTCT use of data should be considered in
countries with generalized epidemics.
Surveillance activities for concentrated epidemics
If HIV has been detected in key populations at higher risk, it is very important to understand how the epidemic
is changing and in which areas it may be expanding. In these areas, systematic tracking of HIV prevalence
and risk behaviours among key populations at higher risk should remain the focus (Table 3.2).
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