Secondary Attack Rate of Hepatitis C Virus (HCV)

Introduction and Objectives

The transmission routes of Hepatitis C Virus (HCV) are categorized as horizontal and vertical. The former includes sexual contact, parenteral exposure, and intrafamilial transmission, while the latter pertains to mother-to-child transmission. Although extensive literature has documented the parenteral route and sexual contact, there is a paucity of studies examining intrafamilial transmission within the Mexican population. This study aims to determine the rate of horizontal viral transmission among first-degree relatives of patients diagnosed with HCV infection who received treatment at Hospital de Especialidades No. 14, Centro Medico Nacional "Adolfo Ruiz Cortines."

Materials and Methods

The study design is observational, descriptive, and retrospective. Patient records from outpatient clinics were scrutinized for the period spanning January 2018 to January 2022. Clinical and epidemiological characteristics, risk factors obtained from medical histories, and laboratory results (including positive HCV viral load and HCV serum PCR test) were evaluated to classify cohorts. Informed consent was obtained from all patients. The research work was registered and approved by the Local Research Committee (R-2022-3001-088).

Results

A total of 129 patients were analyzed, with an average age of 39.56 years. Female gender predominated among 68 patients (52.7%), and 29 patients (22.5%) acquired HCV infection. The primary risk factors identified were Systemic Arterial Hypertension (RR: 7.47, 95% CI: 2.951-18.914, p<0.05), Type 2 Diabetes Mellitus (RR: 16.125, 95% CI: 5.985-43.441, p<0.05), and Chronic Kidney Disease (RR: 10.795, 95% CI: 3.736-31.188, p<0.05) (Table 1). Only two patients (6.89%) were classified as having chronic infection based on measured viral load. All patients received Direct-Acting Antiviral treatment, resulting in sustained viral response at three months post-treatment completion. The primary attack rate was 22.48%, the secondary attack rate was 412.5%, and the R₀ was 1,492,953 (Table 2).

Conclusions

The study demonstrated that first-degree relatives with comorbidities are at a higher risk of contracting HCV infection. The study's findings also revealed that the prevalence of HCV infection is higher than the reported rate in the general population. These results highlight the importance of targeted screening programs, especially in high-risk populations with comorbidities, to identify and treat HCV infections promptly. Such efforts will contribute significantly to the international goals for eradicating this virus and preventing further transmission. Moreover, the study's findings underscore the need for increased awareness and preventive measures to reduce the impact of HCV within the Mexican population.

Ethical statement

The protocol was registered and approved by the Ethics Committee. The identity of the patients is protected. Consentment was obtained.

Declaration of interests

None

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Table 1.

Frequency Distribution of Risk Factors in first-degree relatives diagnosed with Hepatitis C Virus (HCV) infection.

Risk Factors		Hepatitis C Virus Infection		p	RR	Lower 95% CI	Upper 95% CI
		No	Yes
Tobacco Use Disorder	Negative	90	24	0.28	1.875	0.585	6.006
	Positive	10	5
Alcoholism	Negative	87	22	0.14	2.129	0.759	5.791
	Positive	13	7
Hypertension	Negative	74	8	<0.05	7.471	2.951	18.914
	Positive	26	21
Diabetes Mellitus, Type 1	Negative	99	29	0.58	0.773	0.704	0.849
	Positive	1	0
Diabetes Mellitus, Type 2	Negative	86	8	<0.05	16.125	5.985	43.441
	Positive	14	21
Pulmonary Disease, Chronic Obstructive	Negative	97	26	0.09	3.731	0.711	19.578
	Positive	3	3
Renal Insufficiency, Chronic	Negative	93	16	<0.05	10.795	3.736	31.188
	Positive	7	13
Immunocompromised	Negative	100	23	<0.05	0.187	0.129	0.27
	Positive	0	6

Table 2.

Calculation of attack rate, secondary attack rate, and R₀ in first-degree relatives diagnosed with Hepatitis C Virus (HCV) infection.

Rate	%
Attack Rate	22.48
Secondary attack rate	412.50
R0	1,492,953

Number of new cases of the disease: 29

Number of infectious contacts: 129

Total number of individuals exposed to an infection, outbreak, or epidemic: 29

Number of individuals who have developed the disease: 129

Total number of susceptible individuals exposed:169

Transmissibility: 161