An epidemic of enterovirus 71 infection among HIV-1-infected orphans in Nairobi

Human infection with enterovirus 71 (EV71) can cause a spectrum of disease with the capacity to cause large epidemics as well as sporadic cases. Affected individuals may be asymptomatic or present with a combination of signs and symptoms. Since 1997, several large epidemics of EV71 infection have been reported [1–6]. Here we report on an outbreak of EV71 infection among residents of an orphanage for HIV-infected children in Nairobi. The presenting clinical manifestations were atypical compared with previous descriptions of EV71 infection. This is the first description of an outbreak of EV71 in such hosts. In 1999, Nyumbani Children's home housed 70 HIV-1-infected orphans. Five children presented with variable prodromal signs and symptoms. Physical signs included conjunctival injection and a papular rash on the trunk and limbs. The latter evolved into linear scabs, spared the palms and soles and faded over 4–12 weeks. Painful swollen cracked lips developed simultaneously in all affected children. Within a week the children complained of pain to the lower limbs, with decreased ambulation and upper limb pain. Muscle symptoms waxed and waned; however, all were ambulatory 2 weeks from the onset of myalgia. The affected children ranged in age from 4 to 11 years, with equal numbers of males and females. Their CDC classification varied between A1 and C3. Possible exposures included visitors to the orphanage, farm animals and pets, regional insects, and well water. Similar signs and symptoms were noted in 18 children who presented at various times in 2000. Relapses were noted in eight after the initial recovery. Secondary spread was reported to HIV-infected children residing in another orphanage from a common school shared by the two homes. Stool and blood samples from children in both homes were tested for the presence of enterovirus RNA by reverse transcriptase–polymerase chain reaction (RT–PCR). In total, 56 clinical samples (10 faeces, 46 sera), collected from 38 children between February 1998 and December 2000 were tested on extracted nucleic acid using random hexamers [7]. The complementary DNA was used in a pan-enterovirus polymerase chain reaction (PCR) using oligonucleotide primers amplifying a region of the 5′ untranslated region (UTR) [7]. Samples for which enterovirus cDNA was amplified were then tested using RT–PCR to amplify regions of the gene encoding VP1 of enterovirus genogroups A, B or C. Subsequent RT–PCR were perfomed using primers specific to regions of the EV71 VP1. VP1 amplicons were further characterized by direct sequencing using the CEQ2000 Dye Terminator Cycle Sequencing Quick Start Kit (Beckman-Coulter, High Wycombe, UK). Sequences were resolved on an automated sequencer (CEQ; Beckman-Coulter). Multiple alignments and phylogenetic analysis for strain characterization were performed using the Clustal and Neighbour Joining methods, and confirmed with the Maximum Parsimony method included in the Bionumerics software (Applied Maths, Kortij, Belgium). Enterovirus RNA (5′UTR) was detected in nine samples collected from eight patients (eight sera and one faeces). None of the samples were RT–PCR positive in the VP1 genogroup-specific PCR (data not shown), but four (two from each orphanage) were positive in the EV71 VP1 PCR and sequence was obtained from two of these amplicons, confirming the presence of EV71 (Table 1). The VP1 partial sequences from these two cases were 90.9 and 98.3% homologous to each other at the nucleotide and amino acid levels, respectively. These two strains grouped within EV71 of genogroup C and were between 98.3 and 99.8% homologus at the amino acid level to other strains within this genogroup isolated in Malaysia, Korea or Taiwan between 1997 and 2000. Sample collection coincided with symptomatic illness in the cases in which EV71 was identified, although three samples were collected before the reported epidemic for other indications.Table 1: Enterovirus-positive patients from the two orpahanges (LTS or COT).A protracted outbreak of EV71 infection occurred among HIV-infected African children residing at two orphanages in Nairobi after large EV71 pandemics in south and south east Asia, and Australia in the preceding 4 years. Initial transmission may have occurred from daily visitors. Secondary spread occurred rapidly, and affected other HIV-infected children through contact at a local school. Although the precise mechanism of spread is unclear, a respiratory or droplet mechanism has been proposed [6]. The constellation of epidemic myalgia, excoriation and lip swelling, and dermatitis in an immunocompromised cohort of children has not previously been described. We believe this outbreak represents an atypical presentation of EV71 infection in an HIV-infected paediatric cohort at risk of serious enteroviral illnesses from impaired humoral immunity [8,9]. None of the children developed the life-threatening complications that have been reported in previous EV71 epidemics. Nevertheless, the outbreak was associated with considerable morbidity, and in susceptible populations may result in significant mortality. Anticipatory planning could be considered. Acknowledgements The authors would like to thank Professor Aggrey N'yongo (deceased) for reviewing biopsy and tissue specimens in Nairobi, and Mr Clive Wells and Dr Rino Cerio for the further evaluation of these specimens in the UK. They would also like to thank Drs Beatrice Aluvaala, Aaron Pulver and Laurie Self Pulver, and Mr Simon Ogola for assistance with data collection, and Professors Kevin De Cock and Sarah Rowland-Jones for advice. Sponsorship: This work was supported by the Medical Research Council of the UK. R.C. was an MRC Clinical Training Fellow. This work was completed at the MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford, UK.