**13. Prevention and control**

Prompt diagnosis and treatment of infected individuals and public education of sexually active populations on proper prevention and prophylactic measures for STIs are the foundation of STI prevention and control. To be successful this approach should be supplemented with screening programs to identify individuals with subclinical infections as many, if not most, STIs are transmitted by individuals who do not know they are infected. However, the lack of adequate diagnostic capacity in most tropical settings severely compromises diagnosis and screening for STIs. This is the biggest barrier to addressing the STI epidemic in the developing world. Provision of a minimal diagnostic capacity, both equipment and trained individuals, at the initial point of contact with STI patients would yield enormous benefits. The development of affordable point-of care tests for STIs would also significantly advance efforts for controlling STIs in these countries. Public health education initiatives for STIs should encourage safe sex behavior and emphasize the advantages of prompt access to healthcare for suspected infections. Education is key to changing sexual behavior in high risk groups, especially adolescents and young adults who

of 14 days. WHO recommends the addition of a parenteral aminoglycoside, such as gentamicin, for the therapy of HIV-positive patients. Treatment should be continued until complete healing is achieved. The intracellular residence of *C. granulomatis* makes it

Travel is known to be a major factor in the spread of STIs around the world, particularly in developing countries where STIs are endemic and very high rates are encountered in commercial sex workers. The rapid spread of antibiotic resistance around the world for a number of STIs and the spread of HIV infection are cases in point. It is difficult to assess the risk of acquiring STIs during travel in which sexual acts occur. Poverty and lack of legal enforcement certainly facilitate access to sexually compliant individuals in the developing world. In addition, risk-taking behavior increases when on vacation and often vacations involve higher risk activities than the traveler typically encounters at home. Studies have shown that engaging in sexual activity is the specific reason for travel, i.e. 'sex vacations', in some travelers. Reports of lower condom rate usage and higher rates of engagement in anonymous sex by travelers support a conclusion of increased risk. Travel clinics and physicians advising overseas travelers should counsel travelers about the risks and proper prophylactic regimens available. Travelers should also be strongly encouraged to be tested for STIs upon return if they have engaged in sexual activity. There are high rates of asymptomatic infection for many STIs and long incubation periods can also occur before there is an onset of symptoms. Immigrants and refugees pose a problem to the health care system in developed countries as well. STIs uncommon in the developed world such as chancroid, LGV, and donovanosis present a diagnostic challenge to the physician unfamiliar with these diseases. Incorrect diagnosis and subsequent incorrect treatment can delay resolution of the disease and increase the risk to the patient and sex partners, even permitting local mini-epidemics of new STIs. Health care providers should be aware of uncommon STIs present in their patient's country of origin when evaluating symptoms of

Prompt diagnosis and treatment of infected individuals and public education of sexually active populations on proper prevention and prophylactic measures for STIs are the foundation of STI prevention and control. To be successful this approach should be supplemented with screening programs to identify individuals with subclinical infections as many, if not most, STIs are transmitted by individuals who do not know they are infected. However, the lack of adequate diagnostic capacity in most tropical settings severely compromises diagnosis and screening for STIs. This is the biggest barrier to addressing the STI epidemic in the developing world. Provision of a minimal diagnostic capacity, both equipment and trained individuals, at the initial point of contact with STI patients would yield enormous benefits. The development of affordable point-of care tests for STIs would also significantly advance efforts for controlling STIs in these countries. Public health education initiatives for STIs should encourage safe sex behavior and emphasize the advantages of prompt access to healthcare for suspected infections. Education is key to changing sexual behavior in high risk groups, especially adolescents and young adults who

**12. STIs among travelers and immigrants from the tropics** 

somewhat resistant to treatment.

genital infection in this population.

**13. Prevention and control** 

are disproportionately afflicted by STIs. Some health care advisors have advocated a policy of treating all sexually active adolescents and adults in a village or locale as a means to controlling STIs, an approach similar to mass treatment with anti-helminthics utilized to control the endemic of intestinal worm disease. This approach may be the single most cost effective mechanism for managing the STI epidemic in developing countries and should be given careful consideration. Although perhaps not applicable for all STIs, certainly for highly prevalent STIs with drugs that are inexpensive, safe, efficacious, and well tolerated, such as metronidazole for treating trichomoniasis, this approach has much merit.

On an individual basis the only truly reliable protection is abstinence from sexual activity. People in long term monogamous relationships also have greatly reduced risk of STIs and HIV. Vaccines are available for the prevention of HPV infection and potential HIV vaccines are in clinical trials. Protective measures for sexually active individuals include reducing the number of sexual partners and the use of latex condoms and other barriers during sexual activity. Consistent and proper use of condoms has been shown to reduce the transmission of STIs and HIV. Male circumcision has also been shown to be significantly protective against transmission of HIV and STIs. STI treatment should include sexual partners of the index case whenever possible to prevent re-infection and to reduce disease transmission. Due to compliance issues and difficulties in following patients in many locales, directly observed single dose therapies are preferred for the treatment of STIs.

#### **14. The future: Vaccines for STIs**

Vaccination offers the ultimate tool for control of STIs; prevention before exposure. Safe and efficacious vaccines could eliminate the vast majority of STI-associated morbidity and mortality. Unfortunately this goal has only been attained relative to HPV infection (section 9.5) and prospects for additional STI vaccines in the immediate future are remote. In part, this is because the precise correlates of protective immunity have not been well-defined for these STIs. However, some progress has been made in the development of vaccines for genital herpes and *Chlamydia* infection. Three types of herpes vaccines have shown efficacy in animal models: (i) HSV-2 subunit vaccines combined with adjuvant; (ii) gene delivery vehicles, such as vaccinia virus, *Listeria* or *Salmonella typhimurium*, expressing HSV-2 proteins; and (iii) attenuated (replication-defective) HSV-2 viruses. Subunit vaccines based on herpes glycoproteins gD and gB have failed in two human clinical trials. Live attenuated viruses have not been tested in humans to date although they have shown the most promise in animal models. Recent progress in identification of T-cell epitopes mediating asymptomatic versus symptomatic disease manifestation should enhance future development of a herpes vaccine. *Chlamydia* candidate vaccines containing *Chlamydia* major outer membrane protein (MOMP) with HPV major capsid membrane protein L1, recombinant MOMP with cholera toxin, co-expressed *Chlamydia* Porin B and polymorphic membrane protein-D proteins in a *Vibrio cholerae* ghost delivery system, MOMP-based DNA vaccines, and live attenuated *Chlamydia* organisms have each shown efficacy in animal models but none have advanced to human trials.

Although the lack of progression to disease in some individuals infected with gonorrhea, syphilis, chancroid, and granuloma inguinale and the ability of immune responses to contain and clear infections in others in the absence of treatment indicates the theoretical feasibility of vaccination, progress on the development of a vaccine for these STIs has lagged. The syphilis spirochete, *Treponema pallidum*, has a unique molecular architecture and

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#### **15. References**


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**15. References** 


**27** 

*Spain* 

**Re-Emergence of Malaria and Dengue in Europe** 

Currently, the emergence/reemergence of several vector-borne diseases in Europe is one of the most important threats for Public Health. In recent years, it is well known that global change have led to drastic modifications in the eco-epidemiology of various tropical and subtropical diseases. Global change can be defined as the impact of human activity on the fundamental mechanisms of biosphere functioning. Therefore, global change includes not only climate change, but also habitats transformation, water cycle modification, biodiversity loss, synanthropic incursion of alien species into new territories or introduction of new chemicals in nature. Consequently a holistic approach is a key factor to assessing the likelihood of vector-borne diseases transmission in Europe. Among these vectors, culicid mosquitoes are probably the most important because of its large vectorial capacity and its

Vector species Distribution Indigenous/exotic Vectorial capacity

Exotic (recently imported)

Exotic (first

in 1979)

reported in Albania

(Portugal), The Netherlands

area, Central Europe

**1. Introduction** 

high degree of opportunism (Table 1).

*Ae. albopictus* Mediterranean

*Ae. aegypti* Madeira

Rubén Bueno Marí and Ricardo Jiménez Peydró

*Biodiversidad y Biología Evolutiva, Universitat de València* 

Dengue (DEN), Yellow Fever (YF), Chikungunya (CHIK), West Nile (WN), Japanese encephalitis (JE), Saint-Louis encephalitis (SLE), La Crosse encephalitis (LACE), Murray valley encephalitis (MVE), Western equine encephalitis (WEE), Eastern equine encephalitis (EEE), Venezuelan equine encephalitis (VEE), Myxomatosis (MYX), Avian Malaria (AMAL),

Dirofilariasis (DF)

DEN, YF, CHIK, WN, JE, SLE, LACE, WEE, EEE, VEE,

Jamestown Canyon (JC), Sindbis (SIN), Tahyna (TAH), DF

*Laboratorio de Entomología y Control de Plagas, Inst. Cavanilles de* 

