Data Sources:

• Passive case reporting through the Department of Health reporting system
• Syphilis surveillance, incorporated into the HSS
• Ad hoc STI prevalence studies

A. Passive reporting in the Department of Health System

• From 1994 to 1999, the number of STI cases reported annually averaged about 35,500, with a range from 30, 360 to 50,287. The STIs reported were syphilis and gonorrhea. Cases reported in this system could be inaccurate, thus there is great possibility that cases are underreported (not all social hygiene clinics screened for syphilis), underdiagnosed and even misdiagnosed. Most of STIs diagnosed are based on gram staining and clinical diagnosis only. This (passive reporting system) represents only a small segment of the general population as it represents only the clients catered by the social hygiene clinics, majority of whom are sex workers.
• The health information system of the Department of Health also receives reports on STIs based on diagnosis by syndromes. These reports come from rural health units, and thus may be influenced by the uneven ability to diagnose STIs based on syndrome. In addition, there is underreporting since not all rural health units report to the system.
• Based on the data from this source, the most common STI syndrome in 1998 was vaginal discharge (22, 841 cases, estimated prevalence = of 0.1%), followed by urethral discharge (3169 cases, estimated prevalence = 0.02%) and genital ulcer (462 cases, cases estimated prevalence = 0.001%).

B. Active Surveillance

Syphilis serosurveillance has been incorporated in the HSS since 1994.

• Results of the syphilis serosurveillance (number of cases/ 100) from 1994 to 2001 showed a rate of from (1% to 11%) among vulnerable (high-risk) groups. The highest rates were consistently found among FLSWs and an increasing trend is noted: from 4% in 1999 to 5% in 2001. MSMs showed increasing rates from 3% in 1999 to 5% in 2001. IDUs showed rates between 1% to 11% but there is no clear trend. Rates among the RFSWs were the lowest (1% to 4%). There was decreasing trend for RFSWs starting in 1996 and a rate of 1% has been maintained since 1998.

Signs and symptoms of STI were also determined among sentinel groups in the BSS.

• In general there is a decrease in the proportion of high-risk groups reporting signs and symptoms of STI. The proportion of RFSWs reporting signs and symptoms of STI decreased from 24% in 1999 to 17% in 2001; among FLSWs, this decreased from 25% in 1999 to 17% in 2001 and among MSMs from 19% in 2000 to 11% in 2001. Among IDUs, the proportion remained at 12% in 2001, the same as the rate in 2000.

Information form these two source of active surveillance data seem to be conflicting, (e.g. increase in syphilis rates, decrease in reported signs and symptoms of STI among FLSWs) but it should be noted that data on signs and symptoms of STI are reported data based on interviews and, therefore subject to underreporting.

C. Periodic surveys commissioned and coordinated by the National STI Programme and FETP

Because of the unreliability of passive case reporting, the Department of Health commissioned periodic surveys which are coordinated by the National AIDS STI Prevention and Control Programme and FETP.

Table 8 shows prevalence for various risk groups, based on a total of 12 studies/ reports conducted in at least 18 sites from 1994 to 2002. From the table, it can be seen that bacterial vaginosis was the most prevalent STI among high-risk females, with a figure of as high as 70%, followed by chlamydial infections (up to 36%), then by gonorrhea (up to 31%). Syphilis was the least prevalent among the high-risk female with a prevalence of up to 7%. Among high-risk males, chlamydial infections had the highest prevalence of up to 16%, followed by syphilis (up to 11%), followed by syphilis (up to 11%), followed by gonorrhea which has a rate of < 3%.

Among low-risk females (general population), candidiasis and bacterial vaginosis showed the highest prevalence (up to 36% and 33% respectively), followed by chlamydia, gonorrhea and syphilis. Among low risk males, chlamydial infections showed the highest prevalence rates, followed by gonorrhea and syphilis.

Although with different methods used, various STI surveys have provided an overall picture on STI surveys have provided an overall picture on STI prevalence in sub-populations as shown in the following table.

Table 8. Prevalence of STI among various population groups (1994-1999)
Risk groups/STI	Area	Estimated prevalence %
High-risk females
Chlamydia	Angeles and Manila	36
	Cebu	21
Gonorrhea	Angeles	15-21
	Cebu	24
	Manila	5-10
Syphilis	ASEP sentinel sites	1-7
Bacterial vaginosis	Angeles	60-70
	Manila	40
Candidiasis	Manila	3-5
Low-risk females
Chlamydia	Manila, Baguio
	Cebu, Davao
Gonorrhea	Manila
	Six provinces²
Syphilis	Manila and six provinces
	10 sentinel sites
Bacterial vaginosis	Manila and six provinces
Candidiasis	Manila and six provinces
Medium to high-risk males
Chlamydia	Manila and Angeles
Gonorrhea	Manila and Angeles
Syphilis	ASEP sites and others
Low-risk males
Chlamydia	Various areas³
Gonorrhea	Various areas³
Syphilis	Various areas³

¹Can be Metro Manila. ²Includes six Women's Health and Safe Motherhood Project (WHSMP) project sites - Pangasinan, Palawan, Bohol, Aklan, Zamboanga del Norte and Surigao del Norte. ³Baguio, Cebu, Davao and six WHSMP project sites.

Among the general population, the most recent study conducted by Family Health International (FHI)-WHSMP/ the National AIDS STI Prevention and Control Programme (NASPCP)/WB-UPCPH in six selected sites among women and men and female and male youths from February to May, 2002 showed the following prevalence for each specific STI:

Table 9 - Prevention of STIs in the general population
	CT	NG	Sy	HepB	Tricho	CA	BV
Test Used	PCR	PCR	RPR/TPPA	Rapid immuno-chromatorgraphy/ ELISA	Culture/Wet mount	KOH	Nugent criteria
Group
Women (n=2,408)	5.6	0.8	0.2	3.2	3.2	17.2	28.6
Men (n=207)	4.4	1.1	0.2	9.6
Female Youth (n=298)	7.7	0.7
Male Youth (n=298)	9.0	1.7

Notes: CT=Chlamydia Trachomatis; NG=Neisseria gonorrhea; Sy=syphilis; HepB=Hepatitis B; Tricho=trichomonas vaginalis; CA=Candida albicans; BV=Bacterial vaginosis.

BEHAVIORAL SURVEILLANCE

A. BSS (active surveillance of high-risk groups)

Core behavioral indicators for high-risk behavior include:

1. knowledge of three correct ways to prevent HIV transmission;
2. median number of sex partners per week (per month for MSM);
3. consistent condom use;
4. use of condom with regular or non-regular partner (for the 2001 BSS, regular partners were subdivided into paying and non-paying partners); and
5. health-seeking behavior.

Results of the Behavioral Sentinel Surveillance (BSS) from 1997-2001 include:

The proportion of respondents with knowledge of three correct ways was relatively high in all the risk-groups; however, no significant increase in knowledge from 2000 was recorded for 2001.

Consistent condom use for the past week was generally low (<35%) for all high-risk groups for 2001. The aggregate results showed that no high-risk groups posted significant improvement in the consistency of condom use over time and no high-risk groups reached the 2002 targets for this variable (>50% for RFSW, >40% FLSW, >30% for MSM and >30% for IDU).

Respondents, particularly the female sex workers (FSWs), tended to use condoms more frequently when they had sex with non-regular partners. Consistent condom use rates declined because of the FSWs' non-use of condoms when they had sex with regular partners such as their spouses and boyfriends.

However, there was an observable upward trend in condom use during last sex with regular and non-regular partners particularly among the FLSWs but the proportions were still below the 100% AIDS Surveillance and Education Project (ASEP) target for condom use during the last sex with a non-regular partner.

Among the FSWs, the proportion for condom use during last sex with regular partners was statistically higher for paying compared with non-paying partners.

Likewise, the proportions for condom use during last sex with a regular paying partner were almost similar to the proportions for condom use during the last sex with a non-regular partner. For MSM, condom use was significantly higher for anal than oral sex.

The median number of sex partners for RFSWs was two partners per week which was the same estimate found since 1997; for FLSWS it was four partners per week the same estimate since 1997; for MSM, median number of sex partners per month was three, up from last year's estimate of two sex partners, and for IDUs, it was one per week which has been the same estimate since 1997.

For IDUs, the significant decline in the proportion of IDUs who shared injecting equipment from 1998 to 1999 was negated by a significant increase in needle sharing from 2000-2001. The current level of 87% sharing of injecting equipment was the highest recorded so far in the BSS.

In 2001, the FSWs frequently cited the social hygiene clinics as their consultation site when they experienced signs and symptoms of STI. This was particularly true of RFSWs. The high-risk group, with the poorest health-seeking behavior, were the MSMs as majority either went to non-professionals for help or self-medicated. Among the sentinel sites, it was in Zamboanga City where majority of respondents in the three high-risk groups resorted to self-medication when they have signs and symptoms of STIs.

The groups monitored were FLSWs, customers and potential customers of sex workers (men in red light districts) and young females at risk for prostitution (<18 years old). Fifteen separate surveys were conducted by five non-governmental organizations from May to June 2001 in four cities: Angeles, Cebu, General Santos and Zamboanga. Respondents were selected using non-random, non-probability techniques because there were no complete lists of individuals each risk groups.

More than half of all the groups reported having multiple partners during the reference period (the week before the interview for women and the month before for men); 57% for FLSWs 53% for men and 51% for high-risk young females.

A larger proportion of respondents in the high-risk groups studied used condoms with a commercial partner than with a non-commercial partner: 78% of FLSWs used condoms with a commercial partner (78% in the BSS survey) while 70% of young females at high-risk used condoms with a commercial partner. Only 58% of men said they used condoms with a sex worker. With non-commercial partners, only 26% of FLSWs (42% in the BSS survey), used condoms, while 8% and 17% of young females at high-risk and men, respectively, used condoms.

Condom use was more likely among female respondents who reported that they were always prepared with a condom, who had the ability to negotiate condom use and a willingness to buy condom despite a tight budget. For men, condom use was most strongly linked with ease of obtaining condoms. Condom use was also more likely for those who were reminded by friends to use them.

A higher proportion of respondents in all three risk groups reported seeking medical care for abnormal discharge than for painful urination. FFSWs were more likely to seek appropriate treatment than the other groups, and for this group, seeking appropriate treatment was strongly associated with having a Social Hygiene card.

On sex workers:

A study on commercial sex workers in Metro Manila in 1996 by Ofelia Saniel of the University of the Philippines College of Public Health (UPCPH) showed that the prevalence of "often use" of condoms was 38% among males prostitutes who serve both male and female clients; 22% in male sex workers who serve male clients only and 63% in female prostitutes who serve primarily male clients.

Male prostitutes who used condoms were younger, had higher incomes and had exclusively male clientele compared to male sex workers who never or seldom used condoms. Condom use was also more likely among female prostitutes who had more clients, had foreign clients, had higher incomes and had been in prostitution work for a longer time.

Maridel Borja of UPCPH studied the correlates of condom use among 683 male commercial sex workers in Quezon City and Manila in 1998. MCSWs had high levels of knowledge on transmission of HIV but practiced risky behavior such as having multiple partner, having unprotected sex and engaging in anal sex. The likelihood of using condom decreased among those who had more than two clients during the past two weeks, those who engaged in anal sex with their non-paying male partners, and those who engaged in vaginal sex with their non-paying female partners. Those more likely to practice protected sex consistently were those whose clients who used alcohol prior to their sexual encounter, those with intentions to use condoms consistently and had no aversion for wearing condoms; those who were not concerned that their clients would think they had STD or AIDS, those who did not care if clients would pay more if condoms were not used, those who could talk to their non-paying partners about condom use and those who disagreed that condoms make sex less enjoyable.

On IDUs

A study on 327 drug users in two rehabilitation centers in Metro Manila in 1994 by Jesus Sarol Jr. of the UPCPH found that IDUs were more likely to be multiple drug users, started using illegal drugs earlier, had longer duration of drug use, had more sexual partners, and were more likely to have injecting drug sex partners than IDUs. A majority of IDUs shared needles and syringes while none knew the proper way of disinfecting these.

A series of studies on IDUs in Cebu and Manila by Dayrit et al in 1994 showed that IDUs had moderate levels of knowledge about HIV/AIDS, low levels of knowledge about preventive measures and high incidence of unprotected sex with multiple partners.

Focus group discussions conducted among 45 IDUs in Cebu in 1994 (Ramon Aboitiz Foundation, 1994) found needle and syringe sharing to be the norm, even among people who understood this to be dangerous. The focus group discussion, participants generally flushed needles and syringes with hot or cold water, or with alcohol which are ineffective methods for inactivating HIV.

On OFWs

A study by Caridad Ancheta of the UPCPH on risk behavior of returning OFWs in 1996 showed that of 1027 OFWs composed of 81% males and 19% females, none used injectable drugs. Thirty four percent engaged in sexual activity abroad - 40.4% among men and 6.3% among women. Women and those who were married were less likely to engage in sexual activity abroad. Among the sexually active, 53% used condoms consistently. Those who were more likely to have used condoms consistently were those engaged in vaginal sex only with a casual partner. Almost all have heard about HIV/AIDS but only 56% had adequate knowledge. Adequate knowledge about HIV/AIDS was associated with having attended a lecture on HIV/AIDS in the pre-departure seminar given by the Philippine Overseas Employment Agency of the Department of Labor and Employment.

Data on risky behavior among men in the general population

National representative surveys conducted in the last 10 years on risky behavior in the general population has shown that a majority of the respondents were not at great risk of acquiring and transmitting HIV since those who practiced safer sex behaviors were greater in number than those with unsafe sex behaviors. Table 10 shows selected behavioral indicators for "unsafe" sex practices and injecting drug among Filipinos in selected sexual behavior survey.

Table 10. Comparison of four studies on behavior related to HIV/AIDS among men in the general population.
Indicator	1999 FHI-USAID DLSU three city survey 3615 men 15 -44 years old	1999 UP-CPH UCLA five city survey 3397 adult men	1996 Survey by Trends - MBL four city survey 1205 (16-45 years old)	1990 UP-CPH KABP 1617 men and women 15-59 years old (men=644)
During the past 12 months	%	%	%	%
Multiple sexual partners	12.9	0-1*	12.0	7.0
Money was exchanged for sex	7.1	5.7	7.0	NA
Condom use (ever use)	19.3	38.9	35.0	20.0
Use of injecting drugs (ever use)	6.1	0	5.0	NA

* last six months
* Table modified form Jimenez-Lee book on Male Sexual Risk Behavior and HIV/AIDS, 1999

ESTIMATES OF STI, HIV/AIDS INFECTIONS

Estimate of HIV infection in 2000 put the total number of cases in 2000 at 13,000 cases. Consensus among workshop participants placed the number of cases in 2001 at 6,002 cases, based on the following assumptions:

• 540,000 sex workers (multiplying the previous estimate of 500,000 workers in 2000 by 2% representing population growth rate to account for the increase in sex workers from previous estimate);
• the HIV prevalence rate of 1% for sex workers in 2001 based on the HSS;
• 10,000 as the total number of IDUs based on Department of Health estimate as reported in the book "Revisiting the Hidden Epidemic";
• 2% prevalence rate for IDUs based on HSS data (estimate for prevalence for IDUs is 1% to 3%);
• 40,200,000 as estimate for the population of 15-49 years for 2001 according to the projections of the National Statistics Office; and
• 0.001% as prevalence rate for the general population based on prevalence HIV/AIDS from blood donors screened by the Philippine Red Cross (recognizing that it may underestimate the true magnitude).

Table 11. Estimate of HIV Infection for 2001
	Estimated Population	Estimated Prevalence	Number of HIV/AIDS Cases
Sex Workers	540,000	1%	5,400
IDUs	10,000	2%	200
15-49 population	40,200,000	0.001%	402
Total			6,002

This number is lower than the 2000 estimate of 13,000 reached during the consensus workshop held in 2000, and nearer to the UNAIDS/WHO estimate of 9,400 cases of 2001.

Sexually Transmitted Infections

Based on the most recent study on the prevalence of various STIs among the general population (2002) and an estimated population of 40,200,000 for the age group 15-49 years for 2001, the following estimates are presented.

Table 12. Estimates of STI, 2001
	Low Estimate		High Estimate
	Prevalence	Number of Cases	Prevalence	Number of Cases
Chlamydial infections	5.6	2,251,200	7.7	3,095,400
Gonorrhea	0.7	281,400	1.7	683,400
Syphilis	0.2	80,400

The estimates for chlamydial infections for 2001 are lower that those estimated for 2000 (4,000,000); estimates for gonorrhea are higher (281,400 to 683,400) than for 2000 (240,000) and estimates for syphilis are lower (80,400) than estimates for 2000 (520,000).

DISCUSSIONS AND CONCLUSION

Data from passive surveillance (HIV Registry) show increases in reported numbers of both asymptomatic and symptomatic cases with 1733 cases as of July 2002. However, considering that the HIV infection has been documented in the country since 1984, the reported cumulative number of cases appears to be lower than expected. Active surveillance data also show no rapid increase in HIV transmission in HIV/AIDS epidemic in the Philippines. Estimates of prevalence rates among high-risk groups range from 1% to 3% in certain areas and years, and in the general population, based on screening of blood donors, prevalence is low; 0.001% in 2000 and 0% in 2001. Using these prevalence rates, the estimated number of HIV positive cases as of 2001 was 6002 cases, or 3.5 times than the reported cases in the HIV Registry.

Possible factors that could explain the slow transmission of HIV/AIDS in the Philippines, based results of studies include the following:

1. Sex workers have few sexual partners. The highest median number of sex partners among sex workers is four (among FLSWs) per week or less than one per day; compared with approximately 2.5 and 3.5 sex partners per day in Cambodia and Thailand, this number is very low.
2. The male population has low exposure to sex workers. Survey showed that only 5.7% to 7.1% of males 15-49 years old engaged in sex with sex workers.
3. A majority of the general male population have only one sex partner. Surveys showed that only 1% to 13% of respondents reported having two or more sexual partners.
4. There are few males who engage in anal sex. The 1999 UPCPH-UCLA study showed only 4.4% of the male adult population practiced anal sex.
5. There is low prevalence of ulcerative STIs.
6. There is a small IDU population. The Department of Heath estimated that there are 10,000 IDUs in the country.

Other possible factors which have not been validated, to date, however, are the large number of circumcised males and the geography of the Philippines (e.g. its island character) which serve as barrier to rapid HIV transmission.

Another possible and more probable cause of the slow transmission of HIV in the country is the country's accelerated response to the HIV/AIDS epidemic. The response includes: organized multisectoral action, use of local resources, active engagement of individuals and organizations, early institution of surveillance systems, and a highly creative and concerted intervention effort which include use of peer outreach, social marketing and advocacy of policy reform to reduce structural and environmental constraints to STI/AIDS prevention.

The situation could change however in the next few years if the presence of the following "dangerous" trends are not sufficiently addressed:

• High-risk behavior which include low condom use and sharing of needles and low prevalence of bleach cleaning of instruments among IDUs;
• High prevalence of STI among high-risk groups;
• Poor health-seeking behavior in some high-risk groups particularly FLSWs, MSMs, IDUs and deep sea fishermen (DSF).

In addition, the current sentinel surveillance system may need to be strengthened in terms of sentinel sites and risk groups to be monitored. There may be emerging risk groups not systematically monitored such as the OFWs and child sex workers. Moreover, the surveillance of risk groups such as MSMs, MCSWs and male clients of STI clinics, have been dropped in most of the sentinel sites, and therefore changes in the prevalence of HIV/AIDS in these groups cannot be sufficiently ascertained. The passive surveillance system, on the other hand, suffers from a number of inadequacies, namely underreporting, delay in reporting and multiple reporting of cases.

Based on all available data, and taking into consideration the limitations of the surveillance system, it can be concluded that the HIV/AIDS epidemic in the Philippines remains "low and slow" and a reasonable estimate of the number of HIV infections in 2001 is about 6,002 cases. The persistence of risky behavior among groups such as sex workers, particularly FLSWs, MSMs, IDUs and deep sea fishermen, however, makes highly probable rapid increase in HIV/AIDS infections in the near future.

Source:
Consensus Report on STI, HIV and AIDS Epidemiology
Philippines 2002
In cooperation with the World Health Organization - Regional Office for the Western Pacific
Department of Health - Philippines
pp. 6 & 13-23