Quantitative real-time PCR in Borrelia persica tick-borne relapsing fever demonstrates correlation with the Jarisch-Herxheimer reaction

An observational prospective study based on a large cohort of HIV-negative neurosyphilis patients with particular reference to the Jarisch-Herxheimer reaction

PURPOSE

The purpose of this study is to outline a complete picture of Jarisch-Herxheimer reaction (JHR) in the central nervous system among HIV-negative neurosyphilis patients.

METHODS

A prospective study cohort of 772 cases with almost all stages of neurosyphilis depicted the features of JHR including occurrence rate, risk profiles, clinical manifestations, medical management and prognosis.

RESULTS

The total occurrence rate of JHR was 9.3% (95% CI, 7.3-11.4%), including 4.1% (95% CI, 2.7-5.6%) with severe JHR. The reaction started 5 h after treatment initiation, peaked after 8 h, and subsided after 18 h. Patients with severe JHR experienced a longer recovery time (26 h). Patients with general paresis (OR = 6.825), ocular syphilis (OR = 3.974), pleocytosis (OR = 2.426), or a high CSF-VDRL titre (per log2 titre increase, OR = 2.235) were more likely to experience JHR. Patients with general paresis had an 11.759-fold increased risk of severe JHR. Worsening symptoms included cognitive impairment, mania, nonsense speech, and dysphoria, while symptoms of hallucination, urination disorder, seizures, myoclonus, or aphasia appeared as new-onset symptoms. Neurosyphilis treatment did not need to be interrupted in most patients with JHR and could be reinstated in patients with seizures under supportive medication when JHR subsided.

CONCLUSION

Severe JHR displayed a 4.1% occurrence rate and clinicians should pay particular attention to patients at a higher risk of JHR. The neurosyphilis treatment regime can be restarted under intensive observation for patients with severe JHR and, if necessary, supportive medication should be initiated and continued until the end of therapy.

Infection and seroprevalence of Borrelia persica in domestic cats and dogs in Israel

Background

Relapsing fever borreliosis is an infectious disease caused by bacteria of the genus Borrelia, inflicting recurrent episodes of fever and spirochetemia in humans. Borrelia persica, the causative agent of relapsing fever in Israel, is prevalent over a broad geographic area that extends from India to Egypt. It is transmitted by the soft tick Ornithodoros tholozani and causes disease in humans as well as domestic cats and dogs. The goal of this study was to survey domestic dogs and cats in Israel for infection with B. persica.

Methods

Blood, sera and demographic and clinical data were collected from dogs and cats brought for veterinary care in central Israel. PCR followed by DNA sequencing was used to detect B. persica DNA in blood samples, and an enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies reactive with B. persica antigens in sera from the same animals. This is the first serological survey of B. persica in dogs and the first survey for antibodies reactive with a relapsing fever Borrelia sp. in cats globally.

Results

Four of the 208 dogs (1.9%) and three of 103 cats (2.9%) sampled were positive by PCR for B. persica DNA, and 24 dogs (11.5%) and 18 cats (17.5%) were seropositive for B. persica antigen by ELISA. The ratio between PCR-positivity and seropositivity in both the dog and cat populations was 1:6. All four PCR-positive dogs and two of three PCR-positive cats were seronegative, suggesting a probable recent infection. Thrombocytopenia showed significant association with seropositivity in dogs (P = 0.003). In cats, anemia had a significant association with seropositivity (P = 0.0001), and thrombocytopenia was associated with the combined prevalence of seropositivity or PCR-positivity (P = 0.022).

Conclusions

Borrelia persica infection is more prevalent and widespread in domestic canine and feline populations in Israel than previously thought. Dogs and cats may play a role as reservoirs and sentinels for human infection. Precautions should be taken to prevent transfusion-transmitted infection between blood donor and recipient animals.

Graphic Abstract

Transmission of the Human Relapsing Fever Spirochete Borrelia persica by the Argasid Tick Ornithodoros tholozani Involves Blood Meals from Wildlife Animal Reservoirs and Mainly Transstadial Transfer

Borrelia persica, transmitted by the argasid tick Ornithodoros tholozani, causes human tick-borne relapsing fever in the Middle East and Central Asia. Infection is acquired often when visiting tick-infested caves and reported to be transmitted mainly transovarially between ticks, occasionally infecting humans. To study the epidemiology of this infection, ticks were trapped in 24 caves in 12 geographic zones covering all of Israel and identified morphologically. DNA was extracted from larvae, nymphs, and adult stages from each location and PCR followed by DNA sequencing was performed to identify Borrelia infection, tick species, and tick blood meal sources. We collected 51,472 argasid ticks from 16 of 24 caves surveyed. We analyzed 2,774 O. tholozani ticks, and 72 (2.6%) from nine caves were PCR positive for B. persica Infection rates in male, female, and nymphal ticks (4.4%, 3%, and 3.2%, respectively) were higher than in larva (P < 0.001), with only 3 (0.04%) positive larvae. Presence of blood meal was associated with B. persica infection in ticks (P = 0.003), and blood meals of golden jackals, red foxes, and Cairo spiny mouse were associated with infection (P ≤ 0.043). PCR survey of 402 wild mammals revealed B. persica infection with the highest rates in social voles (22%), red foxes (16%), golden jackals (8%), and Cairo spiny mice (3%). In conclusion, although transovarial tick transmission of B. persica occurs at low levels, ticks apparently acquire infection mainly from wildlife canid and rodents and may eventually transmit relapsing fever borreliosis to humans who enter their habitat.IMPORTANCE Borrelia persica is a spirochete that causes tick-borne relapsing fever in humans in an area that spans from India to the Mediterranean. Until now, it was thought that the soft tick vector of this infection, Ornithodoros tholozani, is also its main reservoir and it transmits B. persica mostly transovarially between tick generations. This study showed that tick infection with B. persica is associated with feeding blood from wild jackals, foxes, and rodents and that transovarial transmission is minimal. Since O. tholozani ticks are found in isolated caves and ruins, it is assumed that wild canids who migrate over long distances have a major role in the transmission of B. persica between remote tick populations, and it is then maintained locally also by rodents and eventually transferred to humans during tick bites. Prevention of human infection could be achieved by restricting entrance of canines and humans to habitats with O. tholozani populations.