Human parvovirus B19 and low hemoglobin levels in pregnant Sudanese women

First report of serological, molecular detection, and characterization of human parvovirus B19 infections among sickle cell anaemia patients in Khartoum State, Sudan

BACKGROUND

Patients with haematological disorders, such as sickle cell anaemia, are at an elevated risk of transient aplastic crisis due to parvovirus B19 infection. The virus targets specific integration sites in the human genome, disrupting cellular division. However, the molecular mechanisms of infection remain poorly understood.

AIM

This study aimed to determine the prevalence of human parvovirus B19 among patients with sickle cell anaemia in Khartoum State, Sudan.

METHODS

Ninety patients (aged <5 to >15 years) with sickle cell disease attending Gaafer Ibnouaf Children's Hospital between November 2016 and February 2017 were recruited. Sera and plasma samples were analyzed. IgG and IgM antibodies were measured using ELISA, and viral DNA was detected in plasma using nested-PCR. Phylogenetic analysis of sequenced B19 strains focused on the overlapping region of the minor (VP1) and major (VP2) capsid protein genes.

RESULTS

Anti-parvovirus B19 IgG antibodies were detected in 57 of 90 patients (63.3 %), while IgM antibodies were present in 7 (7.8 %). Viral DNA was identified in 23 (25.5 %) patients. Among the 23 DNA-positive patients, 7 (30 %) were seronegative for both IgG and IgM antibodies, highlighting the importance of molecular diagnostics in identifying active infections, especially in early stages. Children under 5 years of age exhibited a higher nucleic acid detection rate compared to older age groups, suggesting the importance of molecular testing in younger patients particularly in the early detection of Parvovirus B19 during the acute phase of infection, before the body has developed detectable antibodies and also in immunocompromised children, who may not mount an antibody response detectable by serological methods. Phylogenetic analysis revealed two distinct Sudanese clusters: one (50 % of sequences) formed a unique clade with low similarity to existing genotypes, while the other (50 %) closely resembled genotype 1 A sequences from Iraq, Iran, and Tanzania.

CONCLUSION

Parvovirus B19 antibodies and DNA were detected at high prevalence among Sudanese children with sickle cell anaemia. Screening for parvovirus B19 is critical for patients requiring blood transfusions, particularly those with haematological disorders. This study provides the first report of parvovirus B19 detection, sequencing, and characterization among Sudanese patients with sickle cell anaemia.

Prevalence of parvovirus B19 antibodies in pregnant women in northern Benin

OBJECTIVES

Parvovirus B19 (B19V) infection in pregnancy is generally asymptomatic, but in about 3% it can cause complications, including miscarriage, severe foetal anaemia and foetal hydrops. The seroprevalence in pregnancy ranges from 20% to 82% in Africa, but there are no data for Benin. We therefore retrospectively assessed the seroprevalence of B19V in pregnant women attending the Saint Jean de Dieu Hospital in Tanguiéta, a rural district of Atacora, in northern Benin.

METHODS

We searched for anti-B19V immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies in 227 sequential sera from as many women (mean age 26.3 years, range: 16-41) of whom 30 were in the first trimester, 66 in the second and 131 in the third. Samples that tested positive for IgM were analysed with an immunoblot test and the viral genome (DNA-B19V) was searched for using a polymerase chain reaction.

RESULTS

Of the 227 women, 153 (67.4%) were positive for IgG anti-B19V, 7 (3.1%) for IgM and 73 (32.2%) were non-immune. Six IgM-positive women were also IgG positive. The difference in IgG seroprevalence between trimesters or ages was not statistically significant. Of the seven IgM-positive samples, three were confirmed positive by immunoblot (of which two were DNA-B19V positive), three were indeterminate (DNA-B19V negative) and one was negative (DNA-B19V negative). Of the three women with confirmed positive IgM, two were in the third trimester and one in the second trimester of pregnancy.

CONCLUSIONS

The seroprevalence of anti-B19V IgG among pregnant women in Benin is high and in line with those reported in some African countries. IgM seroprevalence is also similar to that described in some African countries in non-epidemic periods. The low viral load observed depicts non-acute infections, but it is difficult to establish the precise time of the infection, especially for women tested in the second or third trimester of pregnancy, when the observed viremia could be a sign of an acute infection that occurred in the previous trimester. Consequently, clinical follow-up and further investigations to highlight possible foetal consequences are indicated.

Human Parvoviruses May Affect the Development and Clinical Course of Meningitis and Meningoencephalitis

Meningitis and meningoencephalitis are neurological inflammatory diseases, and although routine diagnostics include testing of a wide range of pathogens, still in many cases, no causative agent is detected. Human parvovirus B19 (B19V), human bocaviruses 1–4 (HBoV1–4), and human parvovirus 4 (hPARV4) are members of the Parvoviridae family and are associated with a wide range of clinical manifestations including neurological disorders. The main aim of this study was to determine whether human parvoviruses infection markers are present among patients with meningitis/meningoencephalitis in Latvia as well as to clarify the role of these viruses on the clinical course of the mentioned diseases. Our study revealed HBoV1–4 and B19V genomic sequences in 52.38% and 16.67% of patients, respectively. Furthermore, symptoms such as the presence of a headache and its severity, fatigue, disorientation, and difficulties to concentrate were significantly frequently present in patients with active parvovirus infection in comparison with parvoviruses negative patients, therefore we suggest that HBoV1–4 and B19V infection should be included in the diagnostics to reduce the number of meningitis/meningoencephalitis with unknown/unexplained etiology.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.