Timely implementation of contact tracing to control a focus of transmission of the novel coronavirus in a cluster of co-workers of a multinational liquefied natural gas company, April 2020, Cabo Delgado Province, Mozambique

Auria Ribeiro Banze^1,&, Félix Gundane¹, TonyVidro², Adalberto Boca³, José Paulo Langa¹, Judite, Monteiro Braga¹, Erika Valeska Rossetto⁴, Cynthia Semá Baltazar¹

 

¹National Institute of Health, Maputo, Mozambique, ²District Directorate of Health, Palma, Cabo Delgado, ³Provincial Directorate of Health, Cabo Delgado, ⁴MassGenics, assigned to Mozambique Centers for Disease Control and Prevention, Maputo, Mozambique

 

 

^&Corresponding author
Áuria Vanessa Manuel Ribeiro Banze, Mozambique Field Epidemiology Training Program (Moz FETP), National Health Institute (INS) Maputo, Mozambique. auria.lanice28@gmail.com

 

 

 

 

In December 2019, a cluster of pneumonia cases of unknown etiology was detected in the city of Wuhan, Hubei province in China [1]. On 9 January, coronavirus disease 2019 (COVID-2019) was identified as the cause of this pneumonia [2]. On March 11, 2020, the WHO declared COVID-19 an outbreak of the pandemic [3]. The clinical signs and symptoms of COVID-19 includes fever, dry cough and fatigue, while nasal congestion, rhinorrhea, sore throat and myalgia were relatively rare [4,5].

 

Public Health authorities in the Mozambique developed a COVID-19 national action plan for preparedness and response, whose main objective was reducing the risk of coronavirus introduction and spread and to minimize the pandemic´s negative impact on the health, economy, and daily life of the population [6]. The plan identifies contact tracing as one of the most important strategies to contain disease spread by preventing person-to-person transmission and to reduce transmission chains in the community.

 

The first cases of COVID-19 in Mozambique were reported on 22 March 2020 [7], a total of nine cases in Total in Maputo City with seven (78%) imported cases. The two locally transmitted cases were linked to reported case on March 22. Following the country epidemiological and COVID-19 surveillance strategies, on 1 April, the Mozambican Ministry of Health (MOH) confirmed a case of COVID-19 out of Maputo City, reported in Afungi, the District of Palma, Cabo Delgado Province. The case was the tenth case reported in Mozambique and had no linkage with previous reported cases. Subsequent cases and the epidemic curve indicated sustained local human-to-human transmission [8].

 

To better understand the COVID-19 situation and prevent further transmission in the community, the Instituto Nacional de Saúde (INS) team and local health authorities were deployed to the District of Palma to carry out case investigation and to implement contact tracing. The objective of this Study is to analyze the timely implementation of the tracked contact tracing of the cluster of cases identified through April 8 to control a focus of transmission of the novel coronavirus.

 

Contextualization

 

The Afungi camp is under the management of a multinational company operating a liquefied natural gas plant, located in the Afungi Peninsula, Palma District, Cabo Delgado Province [9]. Palma District is located in the northern part of Cabo Delgado province in the Rovuma Basin and has a border with Tanzania to the north and northwest through the Rovuma River, on the west with the district of Nangade, on the south with the district of Mocímboa da Praia and on the east with the Indian Ocean[10].

 

In addition to community staff and Mozambicans from different provinces, expatriates from different other countries work in the in camp. The Afungi camp has the capacity to accommodate more than 1,000 workers at a time.

 

Exposure history of case with close contacts

 

The index case was a 60-year-old Mozambican male working in the Afungi camp. On March 7, 2020, he travelled on aplane from Maputo, Mozambique to South Africa, with two family members and they returned on the same day. On March 9, he traveled from Maputo to the Afungi camp by plane, on a direct private flight operated by the company. A week after arriving at the camp, two close colleagues reported to be unwell with symptoms of an upper respiratory tract infection. Following their contact to the index case, the two sought clinical care at the camp´s medical clinic.

 

During the index case´s stay at the camp, it was reported he had daily meetings with his team members, the camp leadership management staffs, and with a team of expatriate project managers.

 

On March 15, 18, and 20, he attended meetings in another village (approximately 23 km from the camp) with 55 community members. On March 21, he reported some symptoms: headache, throat ache, and without fever. The health team of the camp diagnosed and treated him for sinusitis. Following records review, the facility clinical register book had cough and headache documented.

 

On March 27, the case presented with a headache, throat irritation, inflammation and pharyngitis, and was diagnosed and treated with analgesic and antibiotics at that time.

 

On March 29, the patient´s respiratory symptoms worsened with a dry cough and the initial clinical condition persisted and he was referred to a private clinic in Maputo. He used private plane and he reports he sat alone and wore a mask while traveling. He arrived in Maputo on March 30 and went to the clinic where oropharyngeal and nasopharyngeal samples were collected and sent for SARS-CoV-2 testing, and on April 1, he was confirmed to be SARS-CoV-2 positive (Figure 1).

 

 

The epidemiological investigation and contact tracing were conducted using existing WHO and Africa CDC guidelines in which all closed contacts of confirmed cases are considered at risk of exposure to SARS-CoV-2 and should be traced. Contacts were defined as having had any exposures with a probable or confirmed COVID-19 case:1) Face-to-face contact at a distance of one meter and for more than 15 minutes, 2) Direct physical contact, 3) Direct treatment from a health professional without using of adequate personal protective equipment, or 4) Other situations according to the risk assessment of the situations (exposure in closed environments, such as meeting rooms, cafeterias, dormitories, and shared transport) during the period from two days before the onset of symptoms of the case and up to 14 days after the onset of symptoms [11,12].

 

All potential contacts were identified, listed and linked to their corresponding case. With the support of the company's clinical team, contacts were traced by phone to assess their clinical status and exposures, using a standardized form adapted from WHO guidelines. The standardized form included socio-demographic characteristics, relationship to the case, travel history, exposure to the case, co-morbidities, clinical history data on COVID-19 and other existing risk factors. At the end of the interview contacts were also provided with educative and preventive information.

 

For the contact follow-up monitoring a form adapted from WHO guidelines was used. The follow-up form variables included demographic information, telephone and physical address and experience of any symptoms suggestive of COVID-19 infection, such as fever (>37.6℃) muscle pain, joint pain, weakness, nausea, vomiting, diarrhea, abdominal pain, headache, shortness of breath, sore throat, cough, and runny nose. Contacts were monitored daily for at least 14 days after their last exposure to a case.

 

For all suspected cases identified among the contacts, in addition to monitoring symptoms, we carried out an investigation in the patient care register book from the camp clinic where we collected data on acute respiratory infections. Oropharyngeal and nasopharyngeal samples were collected from the contacts that were in the Afungi camp and in the community of Palma. They sample were sent to the National Reference Laboratory at INS in Maputo for testing. For SARS-CoV-2 polymerase chain testing and confirmation.

 

Microsoft Excel version 20 was used for data entry and generation of frequencies, tables, and graphs.

 

 

Cluster epidemiological investigation

 

The contacts at Afungi camp and the Palma community were identified, line-listed, traced and investigated. By April 8, a total of 60 contacts were identified and tracked, of which two were family members of the case, 56 were contacts from work (three were health care workers who provided care at the clinic) and two were community members of the district health services team in Palma. Of the 56 work contacts tracked, 33 (59%) were quarantined at Afungi camp (Figure 2). Of the contacts who were no longer at the camp, 10 (18%) were no longer in Mozambique (five were in England, four in Australia and one in the U.S (Figure 2). Fifty (83%) contacts were male. Five of the 60 contacts of the index case developed acute respiratory symptoms in the 14-day period since last exposure to the case; none of them developed severe illness or required hospitalization. From those who developed symptoms, the presentation was classified as moderate severity for all and they experienced fever, two (40%) reported fever, four (80%) nasal congestion, four (80%) headache, two (40%) sore throat, two (40%) cough and two (40%) joint pain according to the workplace clinic register book (Table 1).

 

Laboratory Results

 

As of April 8, we tested 50 (83%) of contacts that were inside of Mozambique, the remaining 10 (17%) contacts that were outside of Mozambique had difficulties accessing testing because they did not meet the testing criteria according to WHO (1).

 

The contacts tested were of the ages 31-64 years, with a median of 39 years. Within the workplace, 33 were tested on site and five were positive (three of these were suspected cases) for COVID-19 (Figure 2). The two contacts from the local community in Palma had a negative result. The 16 contacts that were being monitored in their provinces were tested, of which three were positive (one of these was a suspected case) for COVID-19 (Figure 2).

 

 

After the case was confirmed on April 1, 2020, the local medical team immediately managed to quarantine all co-workers at the scene. There was a delay in tracing individuals who were off site, due to the difficulty of communication because they are dispersed throughout different parts of the country and the world. Immediate screening at the workplace allowed for clinical follow-up, identification of suspected cases, and testing of contacts.

 

Afungi camp is isolated, located in an area of social instability, directly connected to a community, and accommodates people from different parts of the world. The company's work team comes from different provinces in Mozambique and countries with active transmission of COVID-19, which facilitated disease spread in the camp where the first case was confirmed.

 

Of the eight contacts who tested positive for to SARS-CoV-2, four were asymptomatic, which underscores the importance of testing contacts even if they do not develop symptoms. This assessment also suggested that surveillance at points of entry could have failed to identify potential cases who come traveled from countries with active transmission to of COVID-19, since as of April 8, 2020 there was still entry and exit the Afungi camp of people the different countries. More than 500 people live in the camp, and this large number of people on site was likely one of the factors that contributed to the rapid transmission from person to person.

 

 

This study demonstrated the value of immediate contact tracking that was effective in quick implementation of preventive measures to contain disease spread in the first COVID-19 cluster in Afungi camp. Enhanced surveillance is essential to quickly detect groups and minimize the potential risk of widespread transmission in the community.

 

Physical isolation of suspected cases, disinfection of the camp, and implementation of preventive measures, including communication between the camp and the local community, was effective in containing the outbreak and preventing community transmission. This investigation also trained local health staff and camp staff on proper procedure, allowing for better response to later cases. These efforts did not prevent community transmission, but likely delayed it.

 

 

The authors declare no competing interests.

 

 

Conception and design of the investigation: Auria Ribeiro Banze. Implementation of the investigation: Auria Ribeiro Banze, Félix Gundane, Tony Vidro and Adalberto boca. Contribution of materials and tools for analysis: Auria Ribeiro Banze, José Paulo Langa Judite Monteiro Braga, Erika Rossetto and Cynthia Semá Baltazar. Erika Rossetto and Cynthia Semá Baltazar reviewed subsequent versions of the manuscript. All authors read and approved the final manuscript.

 

 

We are grateful to the health team of the multinational liquefied natural gas company and health professionals from the province of Cabo Delgado who participated in this public health response to COVID-19 in Afungi. The authors would like to thank Neha Kamat, Jordan McOwen, and Kristen Heitzinger for critical revision.

 

 

Table 1: Demographic, clinical and laboratory characteristics of the traced contacts, Afungi Camp, Cabo Delgado Province, Mozambique, 2020

Figure 1: Timeline of the investigation of the first COVID-19 case in Afungi camp, Cabo Delgado Province, Mozambique, 2020

Figure 2: Flow of contacts traced from the first COVID-19 case at Afungi camp, Cabo Delgado Province, Mozambique, 2020

 

 

1. World Health Organization. Pneumonia of unknown cause - China[Internet]. WHO; 2020 January 5[cited 2022 Dec 30].


2. World Health Organization. WHO Director-General´s opening remarks at the media briefing on COVID-19 - 11 March 2020[Internet]. WHO; 2020 March 11[cited 2022 Dec 30].


3. World Health Organization. WHO advice for international travel and trade in relation to the outbreak of pneumonia caused by a new coronavirus in China[Internet]. WHO; 2020 Jan 10[cited 2022 Dec 30].


4. Yang X, Yu Y, Xu J, Shu H, Xia J, Liu H, Wu Y, Zhang L, Yu Z, Fang M, Yu T, Wang Y, Pan S, Zou X, Yuan S, Shang Y. Clinical course and outcomes of critically ill patients with SARS-CoV-2 pneumonia in Wuhan, China: a single-centered, retrospective, observational study. Lancet Respir Med[Internet]. 2020 May[cited 2022 Dec 30];8(5):475-481. https://doi.org/10.1016/s2213-2600(20)30079-5 PubMed | Google Scholar


5. Park SE. Epidemiology, virology, and clinical features of severe acute respiratory syndrome coronavirus 2(Sars-cov-2; coronavirus disease-19). Pediatr Infect Vaccine[Internet]. 2020 Apr 3[cited 2022 Dec 30]; 27(1):1-10. https://doi.org/10.14776/piv.2020.27.e9 . Google Scholar


6. Ministério da Saúde, REPÚBLICA DE MOÇAMBIQUE. [National Plan for Preparedness and Response to the Disease due to the new coronavirus (Covid-19)]. Ministério da Saúde, REPÚBLICA DE MOÇAMBIQUE; 2020[cited 2022 Dec 30] Portuguese.


7. Ministério da Saúde, REPÚBLICA DE MOÇAMBIQUE. [First case of Coronavirus confirmed today in Mozambique]. Ministério da Saúde; 2020 Mar 22[cited 2022 Dec 30]Portuguese.


8. World Health Organization Regional Office for Africa [World Health Organization: 10 cases of COVID-19 confirmed in Mozambique][Internet]. World Health Organization Regional Office for Africa ; 2020 April 02[cited 2022 Dec 30] English, Français, Portuguese


9. Impacto. [Project For The Liquefied Natural Gas Plant in Afungi, Cabo Delgado - Resettlement Action Plan][Internet]. Impacto;[cited 2022 Dec 26] Portuguese.


10. Governo da Província de Cabo Delgado. [The District: Geography of the District of Palma] [Internet]. Governo da Província de Cabo Delgado;[cited 2022 Dec 26] Portuguese.


11. World Health Organization. Contact tracing in the context of COVID-19: Interim guidance, 10 May 2020[Internet]. World Health Organization; 2020 May 10[cited 2022 Dec 30]. 7p.Report No.: WHO/2019-nCoV/Contact_Tracing/2020.1


12. Africa CDC. [Guidance on Contact Tracing for COVID-19 Pandemic][Internet]. Africa CDC;[cited 2022 Dec 26] Portuguese.