Stephanie Dellicour 1,2,3 , Florence Diemo4, Kayla Laserson2,3, Feiko ter Kuile1, Meghna Desai2,3 1. Child and Reproductive Health, Liverpool School of Tropical Medicine, UK 2. Kenya Medical Research Institute (KEMRI), Center for Global Health Research (CGHR), Kisumu, Kenya 3. Centers for Disease Control and Prevention (CDC), Atlanta, USA 4. Rarieda District Medical Officer for Health (DMOH), Nyanza Province, Kenya

We read with great interest the article by Otieno-Nyunya and colleagues1. The authors report low prevalence of syphilis 1.8% (95% CI 1.5% to 2.1%) as detected through the Kenya AIDS Indicator Survey (KAIS) for 2007. The authors suggest these findings indicate that elimination of syphilis is a possibility in Kenya. They also show that syphilis testing is common among women attending antenatal care (ANC) clinics and that recent estimates suggest that prevalence of syphilis among pregnant women has declined to less than 1%. Despite this success, we wish to highlight that there may still be pockets of high syphilis prevalence in Kenya.

As part of an ongoing observational study among pregnant women attending ANC in Asembo, Rarieda District, western Kenya, we observed an unexpected high prevalence of syphilis of 11.5% (32/282). The study participants are women living in 33 villages within a 5km radius of the study health facility coming for routine antenatal care, representing the general population in this area (i.e. not selected according to any health related criteria). Antenatal profile laboratory tests are performed by the facility laboratory (supplied by the Kenya Medical Supplies Agency (KEMSA) or Mission for Essential Drugs and Supplies (MEDS)) and are available free of charge for study participants. Overall 282 first ANC clients have been tested for syphilis during the period between February and September 2011. Different tests have been used during that period depending on the supplies provided as follows: VDRL (from Euromedi Equipment LTD, UK) was used from February to beginning of May 2011 with an associated syphilis prevalence of 8% (11/143), treponemal only rapid test (Eurostrip from Euromedi Equipment LTD, UK) from May to July 2011 with a prevalence of 17% (17/101) and another treponemal only rapid test (from Acon Laboratories, USA) from August to September 2011 with a prevalence of 11% (4/38). Note that the latter two treponemal rapid tests show higher prevalence as these reflect both past and current infections. The prevalence of HIV infection in this population of pregnant women is 28% by rapid test (Determine from Alere Medical Company, Japan and Bioline Standard Diagnostics Inc., South Korea, with Uni-Gold Trinity Biotech PLC, Ireland as the tie-breaker).

All the 32 women testing positive for syphilis were asymptomatic and many did not get the prescribed treatment due to costs (one dose of Benzathine Penicillin and Erythromycin cost Ksh 300 equivalent to ~USD 3); 13 reported no treatment and 11 reported incomplete treatment out of 27 with follow up data. Untreated pregnancies can result in adverse outcomes due to syphilis, such as spontaneous abortion or stillbirth, neonatal death, low birth weight/premature birth or congenital infection of the newborn in up to 80% of cases.23 Furthermore due to the stigma associated with sexually transmitted infections (STIs), even if pregnant women get treated, their partners most often will not.

Similar high prevalence has since been reported at the district level. Collated data from monthly health facility reports in the district show 23% prevalence of syphilis for 2009/2010 and 12% for 2010/2011 (DMOH personal communication). These high rates remained unreported as syphilis is no longer a notifiable disease in Kenya since 2009. Furthermore, the prominence of HIV indicators at district and provincial level reporting may also be partly responsible for other STIs being under-reported and overlooked. The prevalence of syphilis, and of STIs in general, is higher in antenatal clients compared to the general population as these represent the sexually active group. Whereas, a few previous studies have shown the prevalence of syphilis among pregnant women in Kenya to range from 3% to 4%,3 4 Otieno-Nyunya et al report a syphilis prevalence of less than 1% in recently pregnant women from the KAIS survey and noted the limitation from this small sub-sample (which included only 1 positive pregnant woman).

The high rate observed in Rarieda district highlights the fact that there might be hot spots which will need to be managed in order to achieve elimination. Screening pregnant women for syphilis provides an important means to monitor population prevalence and of identifying pockets of high syphilis prevalence. In 1940s, western European countries introduced antenatal syphilis screening and management programmes as part of the strategy for syphilis elimination.5 However implementation of antenatal screening for syphilis in low income countries is often poor due to irregular procurement of tests and the additional cost of the syphilis test incurred by ANC clients. Otieno-Nyunya et al report that antenatal syphilis screening is common in Kenya. However, there is considerable variation in the uptake of syphilis testing. In Rarieda district, less than 10% of first ANC clients are tested for syphilis as reported by the health facilities in 2009 and 2010. New simple and user-friendly, point-of -care rapid diagnostic tests for syphilis provide an opportunity to scale- up antenatal syphilis screening even in facilities without laboratory capacity.

The low country-wide population prevalence detected by KAIS is encouraging, but should be interpreted carefully. It will be important to enhance antenatal syphilis screening both for sentinel surveillance and to reduce the incidence of adverse pregnancy outcomes attributable to syphilis as well as congenital syphilis. Maternal syphilis screening and treatment is among the most cost-effective public health interventions. 6 The effect of the antenatal syphilis screening program could be improved through earlier antenatal attendance, as well as expansion to cover free syphilis treatment and explicit efforts to encourage partner notification and treatment. Operational barriers including procurement inconsistencies with syphilis test types and stock outs of both tests and treatment should be addressed. Additionally, more efforts are needed to increase public and health professional awareness of the potential serious consequences of syphilis. All these efforts will be required for disease control and eventually elimination. More emphasis should also be given to HIV uninfected ANC clients who don't currently benefit from free care and treatment. As argued previously, there should be stronger integration between syphilis screening and HIV-PMTCT programmes which have higher level of funding and political commitment. 7 The Kenyan Division of Reproductive Health would benefit from additional support to strengthen national STI program and policies for the antenatal population.

References 1. Otieno-Nyunya B, Bennett E, Bunnell R, Dadabhai S, Gichangi AA, Mugo N, et al. Epidemiology of syphilis in Kenya: results from a nationally representative serological survey. Sex Transm Infect 2011;87(6):521-25. 2. Kamb ML, Newman LM, Riley PL, Mark J, Hawkes SJ, Malik T, et al. A road map for the global elimination of congenital syphilis. Obstet Gynecol Int 2010;2010. 3. Temmerman M, Gichangi P, Fonck K, Apers L, Claeys P, Van Renterghem L, et al. Effect of a syphilis control programme on pregnancy outcome in Nairobi, Kenya. Sex Transm Infect 2000;76(2):117-21. 4. Buve A, Weiss HA, Laga M, Van Dyck E, Musonda R, Zekeng L, et al. The epidemiology of gonorrhoea, chlamydial infection and syphilis in four African cities. AIDS 2001;15 Suppl 4:S79-88. 5. Deperthes BD, Meheus A, O'Reilly K, Broutet N. Maternal and congenital syphilis programmes: case studies in Bolivia, Kenya and South Africa. Bull World Health Organ 2004;82(6):410-6. 6. Vickerman P, Peeling RW, Terris-Prestholt F, Changalucha J, Mabey D, Watson-Jones D, et al. Modelling the cost-effectiveness of introducing rapid syphilis tests into an antenatal syphilis screening programme in Mwanza, Tanzania. Sex Transm Infect 2006;82 Suppl 5:v38-43. 7. Watson-Jones D, Oliff M, Terris-Prestholt F, Changalucha J, Gumodoka B, Mayaud P, et al. Antenatal syphilis screening in sub-Saharan Africa: lessons learned from Tanzania. Trop Med Int Health 2005;10(9):934-43.

Conflict of Interest:

None declared