Hepatitis D coinfection found in ‘household clusters’ in Cameroon

Investigation into the epidemiology of hepatitis D in Cameroon revealed intrahousehold infection and large differences in prevalence between regions, with cases concentrated in forested areas close to the equator, which has been seen in other tropical areas.

“Central Africa has the unfortunate peculiarity of being highly endemic for infection with HIV, hepatitis B virus (HBV), hepatitis C virus (HCV) and hepatitis delta virus (HDV) so that concomitant infections with more than one of these pathogens occur frequently,” Arnaud Fontanet, MD, DrPH, from the Institut Pasteur in Paris, France, and colleagues wrote. “While much attention has been paid to the first three, relatively little is known about the epidemiology of HDV and its interactions with the other blood-borne viruses. Here, we extend [previous work in HCV] to HBV and HDV, and investigate the distribution and risk factors of HDV infection in Cameroon.”

Of the 14,510 participants in the study, 1,621 (11.9%) were positive for HBV surface antigen and 224 of those with HBV were seropositive for HDV. These data led to an estimate of 1,160,799 HBsAG-positive individuals and 122,910 HDV-seropositive individuals in the 15 years to 49 years age group in 2011.

While HDV antibody prevalence did not vary by sex or age, the researchers found variations between regions and ethnic groups. The HDV prevalence was 50% in Sud and 54% in Est, whereas the prevalence ranged between 1% and 19% in the remaining 10 regions (P < .0001). By similar variance, HDV prevalence was 49% among Eastern Bantus and 25% in Southern Bantus, whereas the prevalence ranged between 3% and 8% in the remaining ethnic groups. (P < .0001).

Additionally, the researchers observed a “pronounced South to North gradient” in HDV prevalence, from 28.3% under 4°N down to 4.2% above 9.6° N.

Among the 239 households with at least two individuals with HBV, if HDV seropositivity was randomly distributed across individuals of these households, the expected number of households with at least one case of HDV seropositivity would be 48 (95% CI, 44-50).

However, the observed number was 31, which Fontanet and colleagues noted was significantly lower than expected and suggested an intra-household clustering of cases. Similarly, the observed number of houses with two or more cases of HCV seropositivity was significantly higher than expected by chance, indicating clustering of infected individuals within a household.

“It is noteworthy that in the family with four chronically infected with HBV, all four were co-infected with HDV,” they wrote. “Likewise, of the three families with all three chronically infected with HBV, all three were coinfected with HDV in two families, and two out of three were co-infected with HDV in the remaining.”

Multivariate analysis showed that HDV seropositivity correlated independently with living with an HDV-infected person (OR = 8.8; 95% CI, 3.23- 24), being infected with HIV (OR = 2.82; 95% CI, 1.32- 6.02) and living in the South below a latitude less than 4° N while having rural or outdoor work (OR = 15.2; 95% CI, 8.35-27.6).

“In this study, in households with three or four HBV-infected members, once HDV was introduced, almost all HBV-infected household members became co-infected with HDV,” Fontanet and colleagues concluded. “The preselection of households with substantial HBV transmission for HDV transmission to occur, and the possible shared routes of transmission between the two viruses, may explain the high level of intra-household clustering of HDV.” – by Talitha Bennett

Disclosures: The authors report no relevant financial disclosures.