The study of herpes simplex virus (HSV) epidemiology has gained increased attention due to the association between herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus (HIV), as well as the development of HSV vaccines.
This article aims to provide a comprehensive overview of herpes prevalence in Morocco, drawing on existing research and data to highlight the seroprevalence of HSV-1 and HSV-2 infections and their implications for public health. Population based data on HSV-1 and HSV-2 will be useful for designing potential HSV-2 vaccination strategies and for focusing prevention efforts for HSV-1 and HSV-2 infection.
Herpes Simplex Virus (HSV)
Global Context of HSV Infections
Herpes simplex virus (HSV) is a double-stranded DNA genera that contains two members, HSV-1 and HSV-2 cause persistent infection with recurrent lesions. A type called HSV-1 causes mainly oral infections like herpes labialis or cold sores and another, HSV-2 mostly genital ones. The lesions of HSV-1 and HSV-2 are indistinguishable per Clinique, however, both are primarily spread through direct contact. Almost 700 million people are living with HSV-2 worldwide and the prevalence is highest in some parts of Africa and the Americas whereas Asia has lower rates.
The Centers for Disease Control estimates that too many people, approximately one in six sexually active adults suffer from genital herpes most of them women. High rates are also observed in parts of sub-Saharan Africa, where there is a high prevalence of HIV with up to 80% of HIV-positive teenagers from South Africa being seropositive for HSV-2, as well as 20% of their corresponding healthy controls. HSV-2 prevalence varies markedly by individual characteristics such as gender, age, sexual behaviour, marital status, education, and race.
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Most incident genital herpes infections do not present as recognized clinical syndromes but rather are experienced as subclinical or unrecognized. Indeed, asymptomatic infection is perhaps the most important factor in maintaining virus circulation; many cases of genital herpes are transmitted by individuals who have no clinical awareness of their infected status.
Methodology of Seroprevalence Studies
To estimate the age and sex specific seroprevalence of HSV-1 and HSV-2 infections in selected populations in Brazil, Estonia, India, Morocco, and Sri Lanka serum samples were collected from various populations including children, antenatal clinic attenders, blood donors, hospital inpatients, and HIV sentinel surveillance groups.
Male military personnel in Morocco and STD clinic attenders were enrolled in Sri Lanka. Sera were tested using a common algorithm by type specific HSV-1 and HSV-2 antibody assay.
Seroprevalence of HSV-1 and HSV-2
13 986 samples were tested, 45.0% from adult females, 32.7% from adult males, and 22.3% from children. The prevalence of HSV-1 varied by site ranging from 78.5%-93.6% in adult males and from 75.5%-97.8% in adult females. In all countries HSV-1 seroprevalence increased significantly with age (p<0.001) in both men and women.
The prevalence of HSV-2 infection varied between sites. Brazil had the highest age specific rates of infection for both men and women, followed by Sri Lanka for men and Estonia for women, the lowest rates being found in Estonia for men and India for women. In all countries, HSV-2 seroprevalence increased significantly with age (p<0.01) and adult females had higher rates of infection than adult males by age of infection.
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HSV-1 and HSV-2 seroprevalence was consistently higher in women than men, particularly for HSV-2.
HSV-2 Seroprevalence in Sokoto, Nigeria: A Case Study
To provide a more detailed perspective, let's consider a study conducted in Sokoto, Nigeria, which offers insights into HSV-2 seroprevalence in a specific African population. This cross-sectional study was conducted at the outpatient clinic of the Specialist Hospital, Sokoto. Patients who visited the outpatient clinic between April and August of 2023 with a fever, which was defined as a body temperature that was higher than 37 degrees Celsius, were included in the study. A laboratory technologist extracted three to four millilitres of venous blood from each participant and placed it in EDTA vials.
A total of 184 plasma samples obtained from febrile patients were evaluated for HSV-2 IgG, and 100 (54.3%) were positive as determined by inhibition assay. three-quarters (95% CI = 80.6-91.4) were aged between 18-37 years, with the age group 23-27 years most commonly affected at 31.5% (58/184). HSV-1 IgG was detected in all age cohorts, with the fewest numbers detected in individuals aged ≤53 years (n = 6). All six of the patients, aged 43 to 47, tested positive for the virus.
The seroprevalence of HSV-2 IgG did not differ significantly by age (p = 0.729). It includes more females (122/184) than males (62/184). Of women, 66.3% (122/184) were enrolled with fever, nearly twofold compared with men. Men had a higher prevalence of HSV-2 IgG than women (67.7%, 42/62 vs. 47.5%, 58 /122, P < 0.0001).
On the other hand, a significantly higher proportion of HSV-2 IgG seropositivity (65%, 52/80) was recorded among single individuals than for married ones (48.3%; 54 out of 112); however, this difference did not reach a statistical significance level via chi-square test, p =.141).
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Concerning knowledge of HSV-2, results showed that 91.3% (168/184) patients did not know the virus at all and only 8.7% or n =16/184 ever heard of genital herpes. Seventy-five percent (12/16) of 19 who were aware had HSV-2, compared to over half of the total population at risk unaware124(88/168), P = 0.220.
Table 1: HSV-2 Seroprevalence by Age Group
| Age Group | Number of Patients | HSV-2 Positive | Percentage |
|---|---|---|---|
| 43-47 years | 6 | 6 | 100% |
| Other ages | 178 | 94 | 52.8% |
Comparative Data from Other Regions
The epidemiology of herpes simplex is of substantial epidemiologic and public health interest. Large differences in HSV-1 seroprevalence are seen in different European countries. The typical age at which HSV-1 infection is acquired ranges from 5 to 9 years in Central and Eastern European countries like Bulgaria and the Czech Republic, to over 25 years of age in Northern European countries such as Finland, The Netherlands, Germany, and England and Wales.
Young adults in Northern European countries are less likely to be infected with HSV-1. HSV-2 seropositivity is widely distributed in Europeans older than 12, although there are large differences in the percentage of the population exposed to HSV-2. Women are more likely to be seropositive than men, and likely acquire the virus at an earlier age.
About 1 in 6 Americans (16.2%) aged 14 to 49 is infected with HSV-2. The most affected group was black women, with a prevalence rate of 48%. Prevalence increased with age and number of partners.
HSV-2 is more common in Sub-Saharan Africa than in Europe or the North America. Up to 82% of women and 53% of men in Sub-Saharan Africa are seropositive for HSV-2. In most African countries, HSV-2 prevalence increases with age.
Relative to rates in Europe and North America, HSV-2 seroprevalence is high in Central and South America. HSV-2 infects about 30% of women over 30 years old in Colombia, Costa Rica, Mexico, and Panama.
Implications and Future Directions
The results highlight the public health implications of HSV-2 in Nigeria, given that anti-HSV-2 testing is not generally available and infants would be at high risk from neonatal transmission with possible complications during delivery. The number of seropositive patients is indicative that many are probably unaware of their infection because HSV-2 infections often remain asymptomatic. They are consequently a population with increased susceptibility to HIV because HSV-2 infection can be expected. HSV-2 establishes a lifelong infection with periods of recurrent disease, leaving such patients reservoirs for the virus.
Public awareness and information on genital herpes, the many ways by which it may be transmitted and its public health importance based on high seroprevalence of HSV-2 in this study is necessary. Future research should focus on whether patients with frequent fever need to be investigated for HSV-2 antibodies and such studies can reveal findings that are statistically significant if done in a larger study population.
In conclusion, it is crucial to raise public awareness about genital herpes and its transmission modes, given the high seroprevalence of HSV-2. Further research should investigate whether patients with frequent fever should be screened for HSV-2 antibodies to provide more statistically significant findings.
Genital Herpes: Types, Symptoms, and Treatment | Mass General Brigham
Genital Herpes
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