Chagas disease in the United Kingdom: A review of cases at the Hospital for Tropical Diseases London 1995-2018. The current state of detection of Chagas disease in the UK.

BACKGROUND: Chagas disease (CD), is a parasitic disease endemic in Latin America. Presentation in non-endemic areas is either in the asymptomatic indeterminate phase or the chronic phase with cardiac and/or gastrointestinal complications. METHODS: The Hospital for Tropical Diseases (HTD) based in central London, provides tertiary care for the management of CD. We reviewed all cases managed at this centre between 1995 and 2018. RESULTS: Sixty patients with serologically proven CD were identified. Most were female (70%), with a median age at diagnosis of 41 years. Three quarters of the patients were originally from Bolivia. 62% of all patients were referred to the HTD by their GP. Nearly half of the patients were asymptomatic (47%). Twelve patients had signs of cardiac involvement secondary to CD. Evidence of gastrointestinal damage was established in three patients. Treatment was provided at HTD for 31 patients (47%). Most patients (29) received benznidazole, five of them did not tolerate the course and were switched to nifurtimox. Of the seven patients receiving this second line drug, five completed treatment, whilst two interrupted it due to side effects. CONCLUSIONS: Despite the UK health system having all the resources required to diagnose, treat and follow up cases, there is lack of awareness of CD, such that the vast majority of cases remain undiagnosed and therefore do not receive treatment. We propose key interventions to improve the detection and management of this condition in the UK, especially in pregnant women and neonates.

Visceral Leishmaniasis in Traveler to Guyana Caused by Leishmania siamensis, London, UK.

The parasite Leishmania siamensis is a zoonotic agent of leishmaniasis; infection in animals has been documented in Europe and the United States. Reported authochthonous human infections have been limited to Thailand. We report a case of human visceral Leishmania siamensis infection acquired in Guyana, suggesting colonization in South America.

A large proportion of P. falciparum isolates in the Amazon region of Peru lack pfhrp2 and pfhrp3: implications for malaria rapid diagnostic tests.

BACKGROUND: Malaria rapid diagnostic tests (RDTs) offer significant potential to improve the diagnosis of malaria, and are playing an increasing role in malaria case management, control and elimination. Peru, along with other South American countries, is moving to introduce malaria RDTs as components of malaria control programmes supported by the Global Fund for AIDS, TB and malaria. The selection of the most suitable malaria RDTs is critical to the success of the programmes. METHODS: Eight of nine microscopy positive P. falciparum samples collected in Iquitos, Peru tested negative or weak positive using HRP2-detecting RDTs. These samples were tested for the presence of pfhrp2 and pfhrp3 and their flanking genes by PCR, as well as the presence of HRP proteins by ELISA. To investigate for geographic extent of HRP-deleted parasites and their temporal occurrence a retrospective study was undertaken on 148 microscopy positive P. falciparum samples collected in different areas of the Amazon region of Peru. FINDINGS: Eight of the nine isolates lacked the pfhrp2 and/or pfhrp3 genes and one or both flanking genes, and the absence of HRP was confirmed by ELISA. The retrospective study showed that 61 (41%) and 103 (70%) of the 148 samples lacked the pfhrp2 or pfhrp3 genes respectively, with 32 (21.6%) samples lacking both hrp genes. CONCLUSIONS: This is the first documentation of P. falciparum field isolates lacking pfhrp2 and/or pfhrp3. The high frequency and wide distribution of different parasites lacking pfhrp2 and/or pfhrp3 in widely dispersed areas in the Peruvian Amazon implies that malaria RDTs targeting HRP2 will fail to detect a high proportion of P. falciparum in malaria-endemic areas of Peru and should not be used. RDTs detecting parasite LDH or aldolase and quality microscopy should be use for malaria diagnosis in this region. There is an urgent need for investigation of the abundance and geographic distribution of these parasites in Peru and neighbouring countries.

Gnathostomiasis, another emerging imported disease.

Gnathostomiasis is a food-borne zoonosis caused by the late-third stage larvae of Gnathostoma spp. It is being seen with increasing frequency in countries where it is not endemic and should be regarded as another emerging imported disease. Previously, its foci of endemicity have been confined to Southeast Asia and Central and South America, but its geographical boundaries appear to be increasing, with recent reports of infection in tourists returning from southern Africa. It has a complex life cycle involving at least two intermediate hosts, with humans being accidental hosts in which the larvae cannot reach sexual maturity. The main risks for acquisition are consumption of raw or undercooked freshwater fish and geographical exposure. Infection results in initial nonspecific symptoms followed by cutaneous and/or visceral larva migrans, with the latter carrying high morbidity and mortality rates if there is central nervous system involvement. We review the literature and describe the epidemiology, life cycle, clinical features, diagnosis, treatment, and prevention of gnathostomiasis.

Plasmodium malariae in Haitian refugees, Jamaica.

Since 1963, reported malaria transmission in Haiti has been restricted to Plasmodium falciparum. However, screening of Haitian refugees in Jamaica in 2004, by microscopic examination, identified P. falciparum, P. vivax, and P. malariae. PCR confirmed the P. malariae and P. falciparum but not P. vivax infections. DNA sequencing and rRNA gene sequences showed transmission of P. malariae. This report confirms that P. malariae is still being transmitted in Haiti.