The convergent epidemiology of tuberculosis and human cytomegalovirus infection

Cytomegalovirus pneumonia in a background of central nervous system tuberculosis

A 32‐year‐old patient, who was on treatment for tuberculous meningitis complicated with venous sinus thrombosis, was referred to the medical unit as he developed new onset fever, cough and shortness of breath. He was in respiratory distress and needed intubation. Investigations revealed elevated liver enzymes, leukopenia, spherocytosis and lower lobe predominant consolidations and diffuse nodules in the high‐resolution computed tomography. He was suspected to have cytomegalovirus (CMV) pneumonia with the above results, and further investigations revealed an extremely elevated CMV viral load. He was treated with ganciclovir followed by valganciclovir for a total of 42 days resulting in a complete recovery. Liver functions resolved with anti‐viral treatment, and he was started on full anti‐tuberculosis (TB) treatment. Further investigations did not reveal evidence of immunosuppression. Association of CMV and TB is explained genetically, although clinical association is rarely described. The presence of either infection should lead to higher degree of suspicion of the respective other condition in relevant clinical setting.

Seroprevalence of Human Cytomegalovirus in Pregnant Women in the Asir Region, Kingdom of Saudi Arabia

BACKGROUND

Human cytomegalovirus (HCMV) infection spreads easily by interpersonal contact.

OBJECTIVE

This study determined the prevalence of seropositivity of cytomegalovirus immunoglobulin G (IgG) in the Asir Region, Kingdom of Saudi Arabia.

METHODS

The study evaluated the seropositivity for cytomegalovirus-specific IgG in 460 females. Collected samples were processed and tested using enzyme-linked immunosorbent assay and specific HCMV IgG.

RESULTS

The study showed that all the respondents aged 15-20 years were seropositive for the HCMV. HCMV seropositive status was recorded in 99.2% of the older patients (>40 years of age). In the remaining age groups, the rate of seropositivity ranged from 95.7 (age range 20-25 years) to 98.9% (age range 30 years).

CONCLUSIONS

In all age groups of females tested, the prevalence of seropositive for HCMV was high, i.e., in the range of 95.7-100%.

Examining the Complex Relationship Between Tuberculosis and Other Infectious Diseases in Children

Millions of children are exposed to tuberculosis (TB) each year, many of which become infected with Mycobacterium tuberculosis. Most children can immunologically contain or eradicate the organism without pathology developing. However, in a minority, the organism overcomes the immunological constraints, proliferates and causes TB disease. Each year a million children develop TB disease, with a quarter dying. While it is known that young children and those with immunodeficiencies are at increased risk of progression from TB infection to TB disease, our understanding of risk factors for this transition is limited. The most immunologically disruptive process that can happen during childhood is infection with another pathogen and yet the impact of co-infections on TB risk is poorly investigated. Many diseases have overlapping geographical distributions to TB and affect similar patient populations. It is therefore likely that infection with viruses, bacteria, fungi and protozoa may impact on the risk of developing TB disease following exposure and infection, although disentangling correlation and causation is challenging. As vaccinations also disrupt immunological pathways, these may also impact on TB risk. In this article we describe the pediatric immune response to M. tuberculosis and then review the existing evidence of the impact of co-infection with other pathogens, as well as vaccination, on the host response to M. tuberculosis. We focus on the impact of other organisms on the risk of TB disease in children, in particularly evaluating if co-infections drive host immune responses in an age-dependent way. We finally propose priorities for future research in this field. An improved understanding of the impact of co-infections on TB could assist in TB control strategies, vaccine development (for TB vaccines or vaccines for other organisms), TB treatment approaches and TB diagnostics.

Sex differences in tuberculosis

Tuberculosis is the most prevalent bacterial infectious disease in humans and the leading cause of death from a single infectious agent, ranking above HIV/AIDS. The causative agent, Mycobacterium tuberculosis, is carried by an estimated two billion people globally and claims more than 1.5 million lives each year. Tuberculosis rates are significantly higher in men than in women, reflected by a male-to-female ratio for worldwide case notifications of 1.7. This phenomenon is not new and has been reported in various countries and settings over the last century. However, the reasons for the observed gender bias are not clear, potentially highly complex and discussed controversially in the literature. Both gender- (referring to sociocultural roles and behavior) and sex-related factors (referring to biological aspects) likely contribute to higher tuberculosis rates in men and will be discussed.